diff --git a/service/Android.bp b/service/Android.bp
index 20ccf06..813a239 100644
--- a/service/Android.bp
+++ b/service/Android.bp
@@ -54,7 +54,7 @@
     sdk_version: "system_server_current",
     min_sdk_version: "30",
     srcs: [
-        ":connectivity-service-srcs",
+        "src/**/*.java",
         ":framework-connectivity-shared-srcs",
         ":services-connectivity-shared-srcs",
         // TODO: move to net-utils-device-common, enable shrink optimization to avoid extra classes
diff --git a/service/lint-baseline.xml b/service/lint-baseline.xml
index 35ea2d3..95c169c 100644
--- a/service/lint-baseline.xml
+++ b/service/lint-baseline.xml
@@ -7,8 +7,8 @@
         errorLine1="            if (tm.isDataCapable()) {"
         errorLine2="                   ~~~~~~~~~~~~~">
         <location
-            file="frameworks/base/services/core/java/com/android/server/ConnectivityService.java"
-            line="781"
+            file="frameworks/base/packages/Connectivity/service/src/com/android/server/ConnectivityService.java"
+            line="787"
             column="20"/>
     </issue>
 
@@ -18,8 +18,8 @@
         errorLine1="                mUserAllContext.sendStickyBroadcast(intent, options);"
         errorLine2="                                ~~~~~~~~~~~~~~~~~~~">
         <location
-            file="frameworks/base/services/core/java/com/android/server/ConnectivityService.java"
-            line="2633"
+            file="frameworks/base/packages/Connectivity/service/src/com/android/server/ConnectivityService.java"
+            line="2681"
             column="33"/>
     </issue>
 
@@ -29,8 +29,8 @@
         errorLine1="            final int callingVersion = pm.getTargetSdkVersion(callingPackageName);"
         errorLine2="                                          ~~~~~~~~~~~~~~~~~~~">
         <location
-            file="frameworks/base/services/core/java/com/android/server/ConnectivityService.java"
-            line="5784"
+            file="frameworks/base/packages/Connectivity/service/src/com/android/server/ConnectivityService.java"
+            line="5851"
             column="43"/>
     </issue>
 
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
new file mode 100644
index 0000000..ed2fe82
--- /dev/null
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -0,0 +1,10071 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server;
+
+import static android.Manifest.permission.RECEIVE_DATA_ACTIVITY_CHANGE;
+import static android.content.pm.PackageManager.FEATURE_BLUETOOTH;
+import static android.content.pm.PackageManager.FEATURE_WATCH;
+import static android.content.pm.PackageManager.FEATURE_WIFI;
+import static android.content.pm.PackageManager.FEATURE_WIFI_DIRECT;
+import static android.content.pm.PackageManager.PERMISSION_GRANTED;
+import static android.net.ConnectivityDiagnosticsManager.ConnectivityReport.KEY_NETWORK_PROBES_ATTEMPTED_BITMASK;
+import static android.net.ConnectivityDiagnosticsManager.ConnectivityReport.KEY_NETWORK_PROBES_SUCCEEDED_BITMASK;
+import static android.net.ConnectivityDiagnosticsManager.ConnectivityReport.KEY_NETWORK_VALIDATION_RESULT;
+import static android.net.ConnectivityDiagnosticsManager.DataStallReport.DETECTION_METHOD_DNS_EVENTS;
+import static android.net.ConnectivityDiagnosticsManager.DataStallReport.DETECTION_METHOD_TCP_METRICS;
+import static android.net.ConnectivityDiagnosticsManager.DataStallReport.KEY_DNS_CONSECUTIVE_TIMEOUTS;
+import static android.net.ConnectivityDiagnosticsManager.DataStallReport.KEY_TCP_METRICS_COLLECTION_PERIOD_MILLIS;
+import static android.net.ConnectivityDiagnosticsManager.DataStallReport.KEY_TCP_PACKET_FAIL_RATE;
+import static android.net.ConnectivityManager.BLOCKED_METERED_REASON_MASK;
+import static android.net.ConnectivityManager.BLOCKED_REASON_LOCKDOWN_VPN;
+import static android.net.ConnectivityManager.BLOCKED_REASON_NONE;
+import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
+import static android.net.ConnectivityManager.TYPE_BLUETOOTH;
+import static android.net.ConnectivityManager.TYPE_ETHERNET;
+import static android.net.ConnectivityManager.TYPE_MOBILE;
+import static android.net.ConnectivityManager.TYPE_MOBILE_CBS;
+import static android.net.ConnectivityManager.TYPE_MOBILE_DUN;
+import static android.net.ConnectivityManager.TYPE_MOBILE_EMERGENCY;
+import static android.net.ConnectivityManager.TYPE_MOBILE_FOTA;
+import static android.net.ConnectivityManager.TYPE_MOBILE_HIPRI;
+import static android.net.ConnectivityManager.TYPE_MOBILE_IA;
+import static android.net.ConnectivityManager.TYPE_MOBILE_IMS;
+import static android.net.ConnectivityManager.TYPE_MOBILE_MMS;
+import static android.net.ConnectivityManager.TYPE_MOBILE_SUPL;
+import static android.net.ConnectivityManager.TYPE_NONE;
+import static android.net.ConnectivityManager.TYPE_PROXY;
+import static android.net.ConnectivityManager.TYPE_VPN;
+import static android.net.ConnectivityManager.TYPE_WIFI;
+import static android.net.ConnectivityManager.TYPE_WIFI_P2P;
+import static android.net.ConnectivityManager.getNetworkTypeName;
+import static android.net.ConnectivityManager.isNetworkTypeValid;
+import static android.net.ConnectivitySettingsManager.PRIVATE_DNS_MODE_OPPORTUNISTIC;
+import static android.net.INetworkMonitor.NETWORK_VALIDATION_PROBE_PRIVDNS;
+import static android.net.INetworkMonitor.NETWORK_VALIDATION_RESULT_PARTIAL;
+import static android.net.INetworkMonitor.NETWORK_VALIDATION_RESULT_VALID;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_CAPTIVE_PORTAL;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_ENTERPRISE;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_FOREGROUND;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_CONGESTED;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_METERED;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_ROAMING;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_SUSPENDED;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_VCN_MANAGED;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_VPN;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_OEM_PAID;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_OEM_PRIVATE;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_PARTIAL_CONNECTIVITY;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_VALIDATED;
+import static android.net.NetworkCapabilities.REDACT_FOR_ACCESS_FINE_LOCATION;
+import static android.net.NetworkCapabilities.REDACT_FOR_LOCAL_MAC_ADDRESS;
+import static android.net.NetworkCapabilities.REDACT_FOR_NETWORK_SETTINGS;
+import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
+import static android.net.NetworkCapabilities.TRANSPORT_TEST;
+import static android.net.NetworkCapabilities.TRANSPORT_VPN;
+import static android.net.NetworkRequest.Type.LISTEN_FOR_BEST;
+import static android.net.shared.NetworkMonitorUtils.isPrivateDnsValidationRequired;
+import static android.os.Process.INVALID_UID;
+import static android.os.Process.VPN_UID;
+import static android.system.OsConstants.IPPROTO_TCP;
+import static android.system.OsConstants.IPPROTO_UDP;
+
+import static java.util.Map.Entry;
+
+import android.Manifest;
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.app.AppOpsManager;
+import android.app.BroadcastOptions;
+import android.app.PendingIntent;
+import android.app.usage.NetworkStatsManager;
+import android.content.BroadcastReceiver;
+import android.content.ComponentName;
+import android.content.ContentResolver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.content.pm.PackageManager;
+import android.database.ContentObserver;
+import android.net.CaptivePortal;
+import android.net.CaptivePortalData;
+import android.net.ConnectionInfo;
+import android.net.ConnectivityDiagnosticsManager.ConnectivityReport;
+import android.net.ConnectivityDiagnosticsManager.DataStallReport;
+import android.net.ConnectivityManager;
+import android.net.ConnectivityManager.BlockedReason;
+import android.net.ConnectivityManager.NetworkCallback;
+import android.net.ConnectivityManager.RestrictBackgroundStatus;
+import android.net.ConnectivityResources;
+import android.net.ConnectivitySettingsManager;
+import android.net.DataStallReportParcelable;
+import android.net.DnsResolverServiceManager;
+import android.net.ICaptivePortal;
+import android.net.IConnectivityDiagnosticsCallback;
+import android.net.IConnectivityManager;
+import android.net.IDnsResolver;
+import android.net.INetd;
+import android.net.INetworkActivityListener;
+import android.net.INetworkAgent;
+import android.net.INetworkMonitor;
+import android.net.INetworkMonitorCallbacks;
+import android.net.INetworkOfferCallback;
+import android.net.IOnCompleteListener;
+import android.net.IQosCallback;
+import android.net.ISocketKeepaliveCallback;
+import android.net.InetAddresses;
+import android.net.IpMemoryStore;
+import android.net.IpPrefix;
+import android.net.LinkProperties;
+import android.net.MatchAllNetworkSpecifier;
+import android.net.NativeNetworkConfig;
+import android.net.NativeNetworkType;
+import android.net.NattSocketKeepalive;
+import android.net.Network;
+import android.net.NetworkAgent;
+import android.net.NetworkAgentConfig;
+import android.net.NetworkCapabilities;
+import android.net.NetworkInfo;
+import android.net.NetworkInfo.DetailedState;
+import android.net.NetworkMonitorManager;
+import android.net.NetworkPolicyManager;
+import android.net.NetworkPolicyManager.NetworkPolicyCallback;
+import android.net.NetworkProvider;
+import android.net.NetworkRequest;
+import android.net.NetworkScore;
+import android.net.NetworkSpecifier;
+import android.net.NetworkStack;
+import android.net.NetworkState;
+import android.net.NetworkStateSnapshot;
+import android.net.NetworkTestResultParcelable;
+import android.net.NetworkUtils;
+import android.net.NetworkWatchlistManager;
+import android.net.OemNetworkPreferences;
+import android.net.PrivateDnsConfigParcel;
+import android.net.ProxyInfo;
+import android.net.QosCallbackException;
+import android.net.QosFilter;
+import android.net.QosSocketFilter;
+import android.net.QosSocketInfo;
+import android.net.RouteInfo;
+import android.net.RouteInfoParcel;
+import android.net.SocketKeepalive;
+import android.net.TetheringManager;
+import android.net.TransportInfo;
+import android.net.UidRange;
+import android.net.UidRangeParcel;
+import android.net.UnderlyingNetworkInfo;
+import android.net.Uri;
+import android.net.VpnManager;
+import android.net.VpnTransportInfo;
+import android.net.metrics.IpConnectivityLog;
+import android.net.metrics.NetworkEvent;
+import android.net.netlink.InetDiagMessage;
+import android.net.networkstack.ModuleNetworkStackClient;
+import android.net.networkstack.NetworkStackClientBase;
+import android.net.resolv.aidl.DnsHealthEventParcel;
+import android.net.resolv.aidl.IDnsResolverUnsolicitedEventListener;
+import android.net.resolv.aidl.Nat64PrefixEventParcel;
+import android.net.resolv.aidl.PrivateDnsValidationEventParcel;
+import android.net.shared.PrivateDnsConfig;
+import android.net.util.MultinetworkPolicyTracker;
+import android.os.BatteryStatsManager;
+import android.os.Binder;
+import android.os.Build;
+import android.os.Bundle;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.IBinder;
+import android.os.Looper;
+import android.os.Message;
+import android.os.Messenger;
+import android.os.ParcelFileDescriptor;
+import android.os.Parcelable;
+import android.os.PersistableBundle;
+import android.os.PowerManager;
+import android.os.Process;
+import android.os.RemoteCallbackList;
+import android.os.RemoteException;
+import android.os.ServiceSpecificException;
+import android.os.SystemClock;
+import android.os.SystemProperties;
+import android.os.UserHandle;
+import android.os.UserManager;
+import android.provider.Settings;
+import android.sysprop.NetworkProperties;
+import android.telephony.TelephonyManager;
+import android.text.TextUtils;
+import android.util.ArrayMap;
+import android.util.ArraySet;
+import android.util.LocalLog;
+import android.util.Log;
+import android.util.Pair;
+import android.util.SparseArray;
+import android.util.SparseIntArray;
+
+import com.android.connectivity.resources.R;
+import com.android.internal.annotations.GuardedBy;
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.util.IndentingPrintWriter;
+import com.android.internal.util.MessageUtils;
+import com.android.modules.utils.BasicShellCommandHandler;
+import com.android.net.module.util.BaseNetdUnsolicitedEventListener;
+import com.android.net.module.util.CollectionUtils;
+import com.android.net.module.util.LinkPropertiesUtils.CompareOrUpdateResult;
+import com.android.net.module.util.LinkPropertiesUtils.CompareResult;
+import com.android.net.module.util.LocationPermissionChecker;
+import com.android.net.module.util.NetworkCapabilitiesUtils;
+import com.android.net.module.util.PermissionUtils;
+import com.android.server.connectivity.AutodestructReference;
+import com.android.server.connectivity.DnsManager;
+import com.android.server.connectivity.DnsManager.PrivateDnsValidationUpdate;
+import com.android.server.connectivity.FullScore;
+import com.android.server.connectivity.KeepaliveTracker;
+import com.android.server.connectivity.LingerMonitor;
+import com.android.server.connectivity.MockableSystemProperties;
+import com.android.server.connectivity.NetworkAgentInfo;
+import com.android.server.connectivity.NetworkDiagnostics;
+import com.android.server.connectivity.NetworkNotificationManager;
+import com.android.server.connectivity.NetworkNotificationManager.NotificationType;
+import com.android.server.connectivity.NetworkOffer;
+import com.android.server.connectivity.NetworkRanker;
+import com.android.server.connectivity.PermissionMonitor;
+import com.android.server.connectivity.ProfileNetworkPreferences;
+import com.android.server.connectivity.ProxyTracker;
+import com.android.server.connectivity.QosCallbackTracker;
+
+import libcore.io.IoUtils;
+
+import java.io.FileDescriptor;
+import java.io.PrintWriter;
+import java.net.Inet4Address;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.UnknownHostException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.ConcurrentModificationException;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.SortedSet;
+import java.util.StringJoiner;
+import java.util.TreeSet;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * @hide
+ */
+public class ConnectivityService extends IConnectivityManager.Stub
+        implements PendingIntent.OnFinished {
+    private static final String TAG = ConnectivityService.class.getSimpleName();
+
+    private static final String DIAG_ARG = "--diag";
+    public static final String SHORT_ARG = "--short";
+    private static final String NETWORK_ARG = "networks";
+    private static final String REQUEST_ARG = "requests";
+
+    private static final boolean DBG = true;
+    private static final boolean DDBG = Log.isLoggable(TAG, Log.DEBUG);
+    private static final boolean VDBG = Log.isLoggable(TAG, Log.VERBOSE);
+
+    private static final boolean LOGD_BLOCKED_NETWORKINFO = true;
+
+    /**
+     * Default URL to use for {@link #getCaptivePortalServerUrl()}. This should not be changed
+     * by OEMs for configuration purposes, as this value is overridden by
+     * ConnectivitySettingsManager.CAPTIVE_PORTAL_HTTP_URL.
+     * R.string.config_networkCaptivePortalServerUrl should be overridden instead for this purpose
+     * (preferably via runtime resource overlays).
+     */
+    private static final String DEFAULT_CAPTIVE_PORTAL_HTTP_URL =
+            "http://connectivitycheck.gstatic.com/generate_204";
+
+    // TODO: create better separation between radio types and network types
+
+    // how long to wait before switching back to a radio's default network
+    private static final int RESTORE_DEFAULT_NETWORK_DELAY = 1 * 60 * 1000;
+    // system property that can override the above value
+    private static final String NETWORK_RESTORE_DELAY_PROP_NAME =
+            "android.telephony.apn-restore";
+
+    // How long to wait before putting up a "This network doesn't have an Internet connection,
+    // connect anyway?" dialog after the user selects a network that doesn't validate.
+    private static final int PROMPT_UNVALIDATED_DELAY_MS = 8 * 1000;
+
+    // Default to 30s linger time-out, and 5s for nascent network. Modifiable only for testing.
+    private static final String LINGER_DELAY_PROPERTY = "persist.netmon.linger";
+    private static final int DEFAULT_LINGER_DELAY_MS = 30_000;
+    private static final int DEFAULT_NASCENT_DELAY_MS = 5_000;
+
+    // The maximum number of network request allowed per uid before an exception is thrown.
+    private static final int MAX_NETWORK_REQUESTS_PER_UID = 100;
+
+    // The maximum number of network request allowed for system UIDs before an exception is thrown.
+    @VisibleForTesting
+    static final int MAX_NETWORK_REQUESTS_PER_SYSTEM_UID = 250;
+
+    @VisibleForTesting
+    protected int mLingerDelayMs;  // Can't be final, or test subclass constructors can't change it.
+    @VisibleForTesting
+    protected int mNascentDelayMs;
+
+    // How long to delay to removal of a pending intent based request.
+    // See ConnectivitySettingsManager.CONNECTIVITY_RELEASE_PENDING_INTENT_DELAY_MS
+    private final int mReleasePendingIntentDelayMs;
+
+    private MockableSystemProperties mSystemProperties;
+
+    @VisibleForTesting
+    protected final PermissionMonitor mPermissionMonitor;
+
+    private final PerUidCounter mNetworkRequestCounter;
+    @VisibleForTesting
+    final PerUidCounter mSystemNetworkRequestCounter;
+
+    private volatile boolean mLockdownEnabled;
+
+    /**
+     * Stale copy of uid blocked reasons provided by NPMS. As long as they are accessed only in
+     * internal handler thread, they don't need a lock.
+     */
+    private SparseIntArray mUidBlockedReasons = new SparseIntArray();
+
+    private final Context mContext;
+    private final ConnectivityResources mResources;
+    // The Context is created for UserHandle.ALL.
+    private final Context mUserAllContext;
+    private final Dependencies mDeps;
+    // 0 is full bad, 100 is full good
+    private int mDefaultInetConditionPublished = 0;
+
+    @VisibleForTesting
+    protected IDnsResolver mDnsResolver;
+    @VisibleForTesting
+    protected INetd mNetd;
+    private NetworkStatsManager mStatsManager;
+    private NetworkPolicyManager mPolicyManager;
+    private final NetdCallback mNetdCallback;
+
+    /**
+     * TestNetworkService (lazily) created upon first usage. Locked to prevent creation of multiple
+     * instances.
+     */
+    @GuardedBy("mTNSLock")
+    private TestNetworkService mTNS;
+
+    private final Object mTNSLock = new Object();
+
+    private String mCurrentTcpBufferSizes;
+
+    private static final SparseArray<String> sMagicDecoderRing = MessageUtils.findMessageNames(
+            new Class[] { ConnectivityService.class, NetworkAgent.class, NetworkAgentInfo.class });
+
+    private enum ReapUnvalidatedNetworks {
+        // Tear down networks that have no chance (e.g. even if validated) of becoming
+        // the highest scoring network satisfying a NetworkRequest.  This should be passed when
+        // all networks have been rematched against all NetworkRequests.
+        REAP,
+        // Don't reap networks.  This should be passed when some networks have not yet been
+        // rematched against all NetworkRequests.
+        DONT_REAP
+    }
+
+    private enum UnneededFor {
+        LINGER,    // Determine whether this network is unneeded and should be lingered.
+        TEARDOWN,  // Determine whether this network is unneeded and should be torn down.
+    }
+
+    /**
+     * used internally to clear a wakelock when transitioning
+     * from one net to another.  Clear happens when we get a new
+     * network - EVENT_EXPIRE_NET_TRANSITION_WAKELOCK happens
+     * after a timeout if no network is found (typically 1 min).
+     */
+    private static final int EVENT_CLEAR_NET_TRANSITION_WAKELOCK = 8;
+
+    /**
+     * used internally to reload global proxy settings
+     */
+    private static final int EVENT_APPLY_GLOBAL_HTTP_PROXY = 9;
+
+    /**
+     * PAC manager has received new port.
+     */
+    private static final int EVENT_PROXY_HAS_CHANGED = 16;
+
+    /**
+     * used internally when registering NetworkProviders
+     * obj = NetworkProviderInfo
+     */
+    private static final int EVENT_REGISTER_NETWORK_PROVIDER = 17;
+
+    /**
+     * used internally when registering NetworkAgents
+     * obj = Messenger
+     */
+    private static final int EVENT_REGISTER_NETWORK_AGENT = 18;
+
+    /**
+     * used to add a network request
+     * includes a NetworkRequestInfo
+     */
+    private static final int EVENT_REGISTER_NETWORK_REQUEST = 19;
+
+    /**
+     * indicates a timeout period is over - check if we had a network yet or not
+     * and if not, call the timeout callback (but leave the request live until they
+     * cancel it.
+     * includes a NetworkRequestInfo
+     */
+    private static final int EVENT_TIMEOUT_NETWORK_REQUEST = 20;
+
+    /**
+     * used to add a network listener - no request
+     * includes a NetworkRequestInfo
+     */
+    private static final int EVENT_REGISTER_NETWORK_LISTENER = 21;
+
+    /**
+     * used to remove a network request, either a listener or a real request
+     * arg1 = UID of caller
+     * obj  = NetworkRequest
+     */
+    private static final int EVENT_RELEASE_NETWORK_REQUEST = 22;
+
+    /**
+     * used internally when registering NetworkProviders
+     * obj = Messenger
+     */
+    private static final int EVENT_UNREGISTER_NETWORK_PROVIDER = 23;
+
+    /**
+     * used internally to expire a wakelock when transitioning
+     * from one net to another.  Expire happens when we fail to find
+     * a new network (typically after 1 minute) -
+     * EVENT_CLEAR_NET_TRANSITION_WAKELOCK happens if we had found
+     * a replacement network.
+     */
+    private static final int EVENT_EXPIRE_NET_TRANSITION_WAKELOCK = 24;
+
+    /**
+     * used to add a network request with a pending intent
+     * obj = NetworkRequestInfo
+     */
+    private static final int EVENT_REGISTER_NETWORK_REQUEST_WITH_INTENT = 26;
+
+    /**
+     * used to remove a pending intent and its associated network request.
+     * arg1 = UID of caller
+     * obj  = PendingIntent
+     */
+    private static final int EVENT_RELEASE_NETWORK_REQUEST_WITH_INTENT = 27;
+
+    /**
+     * used to specify whether a network should be used even if unvalidated.
+     * arg1 = whether to accept the network if it's unvalidated (1 or 0)
+     * arg2 = whether to remember this choice in the future (1 or 0)
+     * obj  = network
+     */
+    private static final int EVENT_SET_ACCEPT_UNVALIDATED = 28;
+
+    /**
+     * used to ask the user to confirm a connection to an unvalidated network.
+     * obj  = network
+     */
+    private static final int EVENT_PROMPT_UNVALIDATED = 29;
+
+    /**
+     * used internally to (re)configure always-on networks.
+     */
+    private static final int EVENT_CONFIGURE_ALWAYS_ON_NETWORKS = 30;
+
+    /**
+     * used to add a network listener with a pending intent
+     * obj = NetworkRequestInfo
+     */
+    private static final int EVENT_REGISTER_NETWORK_LISTENER_WITH_INTENT = 31;
+
+    /**
+     * used to specify whether a network should not be penalized when it becomes unvalidated.
+     */
+    private static final int EVENT_SET_AVOID_UNVALIDATED = 35;
+
+    /**
+     * used to trigger revalidation of a network.
+     */
+    private static final int EVENT_REVALIDATE_NETWORK = 36;
+
+    // Handle changes in Private DNS settings.
+    private static final int EVENT_PRIVATE_DNS_SETTINGS_CHANGED = 37;
+
+    // Handle private DNS validation status updates.
+    private static final int EVENT_PRIVATE_DNS_VALIDATION_UPDATE = 38;
+
+     /**
+      * Event for NetworkMonitor/NetworkAgentInfo to inform ConnectivityService that the network has
+      * been tested.
+      * obj = {@link NetworkTestedResults} representing information sent from NetworkMonitor.
+      * data = PersistableBundle of extras passed from NetworkMonitor. If {@link
+      * NetworkMonitorCallbacks#notifyNetworkTested} is called, this will be null.
+      */
+    private static final int EVENT_NETWORK_TESTED = 41;
+
+    /**
+     * Event for NetworkMonitor/NetworkAgentInfo to inform ConnectivityService that the private DNS
+     * config was resolved.
+     * obj = PrivateDnsConfig
+     * arg2 = netid
+     */
+    private static final int EVENT_PRIVATE_DNS_CONFIG_RESOLVED = 42;
+
+    /**
+     * Request ConnectivityService display provisioning notification.
+     * arg1    = Whether to make the notification visible.
+     * arg2    = NetID.
+     * obj     = Intent to be launched when notification selected by user, null if !arg1.
+     */
+    private static final int EVENT_PROVISIONING_NOTIFICATION = 43;
+
+    /**
+     * Used to specify whether a network should be used even if connectivity is partial.
+     * arg1 = whether to accept the network if its connectivity is partial (1 for true or 0 for
+     * false)
+     * arg2 = whether to remember this choice in the future (1 for true or 0 for false)
+     * obj  = network
+     */
+    private static final int EVENT_SET_ACCEPT_PARTIAL_CONNECTIVITY = 44;
+
+    /**
+     * Event for NetworkMonitor to inform ConnectivityService that the probe status has changed.
+     * Both of the arguments are bitmasks, and the value of bits come from
+     * INetworkMonitor.NETWORK_VALIDATION_PROBE_*.
+     * arg1 = A bitmask to describe which probes are completed.
+     * arg2 = A bitmask to describe which probes are successful.
+     */
+    public static final int EVENT_PROBE_STATUS_CHANGED = 45;
+
+    /**
+     * Event for NetworkMonitor to inform ConnectivityService that captive portal data has changed.
+     * arg1 = unused
+     * arg2 = netId
+     * obj = captive portal data
+     */
+    private static final int EVENT_CAPPORT_DATA_CHANGED = 46;
+
+    /**
+     * Used by setRequireVpnForUids.
+     * arg1 = whether the specified UID ranges are required to use a VPN.
+     * obj  = Array of UidRange objects.
+     */
+    private static final int EVENT_SET_REQUIRE_VPN_FOR_UIDS = 47;
+
+    /**
+     * Used internally when setting the default networks for OemNetworkPreferences.
+     * obj = Pair<OemNetworkPreferences, listener>
+     */
+    private static final int EVENT_SET_OEM_NETWORK_PREFERENCE = 48;
+
+    /**
+     * Used to indicate the system default network becomes active.
+     */
+    private static final int EVENT_REPORT_NETWORK_ACTIVITY = 49;
+
+    /**
+     * Used internally when setting a network preference for a user profile.
+     * obj = Pair<ProfileNetworkPreference, Listener>
+     */
+    private static final int EVENT_SET_PROFILE_NETWORK_PREFERENCE = 50;
+
+    /**
+     * Event to specify that reasons for why an uid is blocked changed.
+     * arg1 = uid
+     * arg2 = blockedReasons
+     */
+    private static final int EVENT_UID_BLOCKED_REASON_CHANGED = 51;
+
+    /**
+     * Event to register a new network offer
+     * obj = NetworkOffer
+     */
+    private static final int EVENT_REGISTER_NETWORK_OFFER = 52;
+
+    /**
+     * Event to unregister an existing network offer
+     * obj = INetworkOfferCallback
+     */
+    private static final int EVENT_UNREGISTER_NETWORK_OFFER = 53;
+
+    /**
+     * Argument for {@link #EVENT_PROVISIONING_NOTIFICATION} to indicate that the notification
+     * should be shown.
+     */
+    private static final int PROVISIONING_NOTIFICATION_SHOW = 1;
+
+    /**
+     * Argument for {@link #EVENT_PROVISIONING_NOTIFICATION} to indicate that the notification
+     * should be hidden.
+     */
+    private static final int PROVISIONING_NOTIFICATION_HIDE = 0;
+
+    private static String eventName(int what) {
+        return sMagicDecoderRing.get(what, Integer.toString(what));
+    }
+
+    private static IDnsResolver getDnsResolver(Context context) {
+        final DnsResolverServiceManager dsm = context.getSystemService(
+                DnsResolverServiceManager.class);
+        return IDnsResolver.Stub.asInterface(dsm.getService());
+    }
+
+    /** Handler thread used for all of the handlers below. */
+    @VisibleForTesting
+    protected final HandlerThread mHandlerThread;
+    /** Handler used for internal events. */
+    final private InternalHandler mHandler;
+    /** Handler used for incoming {@link NetworkStateTracker} events. */
+    final private NetworkStateTrackerHandler mTrackerHandler;
+    /** Handler used for processing {@link android.net.ConnectivityDiagnosticsManager} events */
+    @VisibleForTesting
+    final ConnectivityDiagnosticsHandler mConnectivityDiagnosticsHandler;
+
+    private final DnsManager mDnsManager;
+    private final NetworkRanker mNetworkRanker;
+
+    private boolean mSystemReady;
+    private Intent mInitialBroadcast;
+
+    private PowerManager.WakeLock mNetTransitionWakeLock;
+    private final PowerManager.WakeLock mPendingIntentWakeLock;
+
+    // A helper object to track the current default HTTP proxy. ConnectivityService needs to tell
+    // the world when it changes.
+    @VisibleForTesting
+    protected final ProxyTracker mProxyTracker;
+
+    final private SettingsObserver mSettingsObserver;
+
+    private UserManager mUserManager;
+
+    // the set of network types that can only be enabled by system/sig apps
+    private List<Integer> mProtectedNetworks;
+
+    private Set<String> mWolSupportedInterfaces;
+
+    private final TelephonyManager mTelephonyManager;
+    private final AppOpsManager mAppOpsManager;
+
+    private final LocationPermissionChecker mLocationPermissionChecker;
+
+    private KeepaliveTracker mKeepaliveTracker;
+    private QosCallbackTracker mQosCallbackTracker;
+    private NetworkNotificationManager mNotifier;
+    private LingerMonitor mLingerMonitor;
+
+    // sequence number of NetworkRequests
+    private int mNextNetworkRequestId = NetworkRequest.FIRST_REQUEST_ID;
+
+    // Sequence number for NetworkProvider IDs.
+    private final AtomicInteger mNextNetworkProviderId = new AtomicInteger(
+            NetworkProvider.FIRST_PROVIDER_ID);
+
+    // NetworkRequest activity String log entries.
+    private static final int MAX_NETWORK_REQUEST_LOGS = 20;
+    private final LocalLog mNetworkRequestInfoLogs = new LocalLog(MAX_NETWORK_REQUEST_LOGS);
+
+    // NetworkInfo blocked and unblocked String log entries
+    private static final int MAX_NETWORK_INFO_LOGS = 40;
+    private final LocalLog mNetworkInfoBlockingLogs = new LocalLog(MAX_NETWORK_INFO_LOGS);
+
+    private static final int MAX_WAKELOCK_LOGS = 20;
+    private final LocalLog mWakelockLogs = new LocalLog(MAX_WAKELOCK_LOGS);
+    private int mTotalWakelockAcquisitions = 0;
+    private int mTotalWakelockReleases = 0;
+    private long mTotalWakelockDurationMs = 0;
+    private long mMaxWakelockDurationMs = 0;
+    private long mLastWakeLockAcquireTimestamp = 0;
+
+    private final IpConnectivityLog mMetricsLog;
+
+    @GuardedBy("mBandwidthRequests")
+    private final SparseArray<Integer> mBandwidthRequests = new SparseArray(10);
+
+    @VisibleForTesting
+    final MultinetworkPolicyTracker mMultinetworkPolicyTracker;
+
+    @VisibleForTesting
+    final Map<IBinder, ConnectivityDiagnosticsCallbackInfo> mConnectivityDiagnosticsCallbacks =
+            new HashMap<>();
+
+    /**
+     * Implements support for the legacy "one network per network type" model.
+     *
+     * We used to have a static array of NetworkStateTrackers, one for each
+     * network type, but that doesn't work any more now that we can have,
+     * for example, more that one wifi network. This class stores all the
+     * NetworkAgentInfo objects that support a given type, but the legacy
+     * API will only see the first one.
+     *
+     * It serves two main purposes:
+     *
+     * 1. Provide information about "the network for a given type" (since this
+     *    API only supports one).
+     * 2. Send legacy connectivity change broadcasts. Broadcasts are sent if
+     *    the first network for a given type changes, or if the default network
+     *    changes.
+     */
+    @VisibleForTesting
+    static class LegacyTypeTracker {
+
+        private static final boolean DBG = true;
+        private static final boolean VDBG = false;
+
+        /**
+         * Array of lists, one per legacy network type (e.g., TYPE_MOBILE_MMS).
+         * Each list holds references to all NetworkAgentInfos that are used to
+         * satisfy requests for that network type.
+         *
+         * This array is built out at startup such that an unsupported network
+         * doesn't get an ArrayList instance, making this a tristate:
+         * unsupported, supported but not active and active.
+         *
+         * The actual lists are populated when we scan the network types that
+         * are supported on this device.
+         *
+         * Threading model:
+         *  - addSupportedType() is only called in the constructor
+         *  - add(), update(), remove() are only called from the ConnectivityService handler thread.
+         *    They are therefore not thread-safe with respect to each other.
+         *  - getNetworkForType() can be called at any time on binder threads. It is synchronized
+         *    on mTypeLists to be thread-safe with respect to a concurrent remove call.
+         *  - getRestoreTimerForType(type) is also synchronized on mTypeLists.
+         *  - dump is thread-safe with respect to concurrent add and remove calls.
+         */
+        private final ArrayList<NetworkAgentInfo> mTypeLists[];
+        @NonNull
+        private final ConnectivityService mService;
+
+        // Restore timers for requestNetworkForFeature (network type -> timer in ms). Types without
+        // an entry have no timer (equivalent to -1). Lazily loaded.
+        @NonNull
+        private ArrayMap<Integer, Integer> mRestoreTimers = new ArrayMap<>();
+
+        LegacyTypeTracker(@NonNull ConnectivityService service) {
+            mService = service;
+            mTypeLists = new ArrayList[ConnectivityManager.MAX_NETWORK_TYPE + 1];
+        }
+
+        public void loadSupportedTypes(@NonNull Context ctx, @NonNull TelephonyManager tm) {
+            final PackageManager pm = ctx.getPackageManager();
+            if (pm.hasSystemFeature(FEATURE_WIFI)) {
+                addSupportedType(TYPE_WIFI);
+            }
+            if (pm.hasSystemFeature(FEATURE_WIFI_DIRECT)) {
+                addSupportedType(TYPE_WIFI_P2P);
+            }
+            if (tm.isDataCapable()) {
+                // Telephony does not have granular support for these types: they are either all
+                // supported, or none is supported
+                addSupportedType(TYPE_MOBILE);
+                addSupportedType(TYPE_MOBILE_MMS);
+                addSupportedType(TYPE_MOBILE_SUPL);
+                addSupportedType(TYPE_MOBILE_DUN);
+                addSupportedType(TYPE_MOBILE_HIPRI);
+                addSupportedType(TYPE_MOBILE_FOTA);
+                addSupportedType(TYPE_MOBILE_IMS);
+                addSupportedType(TYPE_MOBILE_CBS);
+                addSupportedType(TYPE_MOBILE_IA);
+                addSupportedType(TYPE_MOBILE_EMERGENCY);
+            }
+            if (pm.hasSystemFeature(FEATURE_BLUETOOTH)) {
+                addSupportedType(TYPE_BLUETOOTH);
+            }
+            if (pm.hasSystemFeature(FEATURE_WATCH)) {
+                // TYPE_PROXY is only used on Wear
+                addSupportedType(TYPE_PROXY);
+            }
+            // Ethernet is often not specified in the configs, although many devices can use it via
+            // USB host adapters. Add it as long as the ethernet service is here.
+            if (ctx.getSystemService(Context.ETHERNET_SERVICE) != null) {
+                addSupportedType(TYPE_ETHERNET);
+            }
+
+            // Always add TYPE_VPN as a supported type
+            addSupportedType(TYPE_VPN);
+        }
+
+        private void addSupportedType(int type) {
+            if (mTypeLists[type] != null) {
+                throw new IllegalStateException(
+                        "legacy list for type " + type + "already initialized");
+            }
+            mTypeLists[type] = new ArrayList<>();
+        }
+
+        public boolean isTypeSupported(int type) {
+            return isNetworkTypeValid(type) && mTypeLists[type] != null;
+        }
+
+        public NetworkAgentInfo getNetworkForType(int type) {
+            synchronized (mTypeLists) {
+                if (isTypeSupported(type) && !mTypeLists[type].isEmpty()) {
+                    return mTypeLists[type].get(0);
+                }
+            }
+            return null;
+        }
+
+        public int getRestoreTimerForType(int type) {
+            synchronized (mTypeLists) {
+                if (mRestoreTimers == null) {
+                    mRestoreTimers = loadRestoreTimers();
+                }
+                return mRestoreTimers.getOrDefault(type, -1);
+            }
+        }
+
+        private ArrayMap<Integer, Integer> loadRestoreTimers() {
+            final String[] configs = mService.mResources.get().getStringArray(
+                    R.array.config_legacy_networktype_restore_timers);
+            final ArrayMap<Integer, Integer> ret = new ArrayMap<>(configs.length);
+            for (final String config : configs) {
+                final String[] splits = TextUtils.split(config, ",");
+                if (splits.length != 2) {
+                    logwtf("Invalid restore timer token count: " + config);
+                    continue;
+                }
+                try {
+                    ret.put(Integer.parseInt(splits[0]), Integer.parseInt(splits[1]));
+                } catch (NumberFormatException e) {
+                    logwtf("Invalid restore timer number format: " + config, e);
+                }
+            }
+            return ret;
+        }
+
+        private void maybeLogBroadcast(NetworkAgentInfo nai, DetailedState state, int type,
+                boolean isDefaultNetwork) {
+            if (DBG) {
+                log("Sending " + state
+                        + " broadcast for type " + type + " " + nai.toShortString()
+                        + " isDefaultNetwork=" + isDefaultNetwork);
+            }
+        }
+
+        // When a lockdown VPN connects, send another CONNECTED broadcast for the underlying
+        // network type, to preserve previous behaviour.
+        private void maybeSendLegacyLockdownBroadcast(@NonNull NetworkAgentInfo vpnNai) {
+            if (vpnNai != mService.getLegacyLockdownNai()) return;
+
+            if (vpnNai.declaredUnderlyingNetworks == null
+                    || vpnNai.declaredUnderlyingNetworks.length != 1) {
+                Log.wtf(TAG, "Legacy lockdown VPN must have exactly one underlying network: "
+                        + Arrays.toString(vpnNai.declaredUnderlyingNetworks));
+                return;
+            }
+            final NetworkAgentInfo underlyingNai = mService.getNetworkAgentInfoForNetwork(
+                    vpnNai.declaredUnderlyingNetworks[0]);
+            if (underlyingNai == null) return;
+
+            final int type = underlyingNai.networkInfo.getType();
+            final DetailedState state = DetailedState.CONNECTED;
+            maybeLogBroadcast(underlyingNai, state, type, true /* isDefaultNetwork */);
+            mService.sendLegacyNetworkBroadcast(underlyingNai, state, type);
+        }
+
+        /** Adds the given network to the specified legacy type list. */
+        public void add(int type, NetworkAgentInfo nai) {
+            if (!isTypeSupported(type)) {
+                return;  // Invalid network type.
+            }
+            if (VDBG) log("Adding agent " + nai + " for legacy network type " + type);
+
+            ArrayList<NetworkAgentInfo> list = mTypeLists[type];
+            if (list.contains(nai)) {
+                return;
+            }
+            synchronized (mTypeLists) {
+                list.add(nai);
+            }
+
+            // Send a broadcast if this is the first network of its type or if it's the default.
+            final boolean isDefaultNetwork = mService.isDefaultNetwork(nai);
+
+            // If a legacy lockdown VPN is active, override the NetworkInfo state in all broadcasts
+            // to preserve previous behaviour.
+            final DetailedState state = mService.getLegacyLockdownState(DetailedState.CONNECTED);
+            if ((list.size() == 1) || isDefaultNetwork) {
+                maybeLogBroadcast(nai, state, type, isDefaultNetwork);
+                mService.sendLegacyNetworkBroadcast(nai, state, type);
+            }
+
+            if (type == TYPE_VPN && state == DetailedState.CONNECTED) {
+                maybeSendLegacyLockdownBroadcast(nai);
+            }
+        }
+
+        /** Removes the given network from the specified legacy type list. */
+        public void remove(int type, NetworkAgentInfo nai, boolean wasDefault) {
+            ArrayList<NetworkAgentInfo> list = mTypeLists[type];
+            if (list == null || list.isEmpty()) {
+                return;
+            }
+            final boolean wasFirstNetwork = list.get(0).equals(nai);
+
+            synchronized (mTypeLists) {
+                if (!list.remove(nai)) {
+                    return;
+                }
+            }
+
+            if (wasFirstNetwork || wasDefault) {
+                maybeLogBroadcast(nai, DetailedState.DISCONNECTED, type, wasDefault);
+                mService.sendLegacyNetworkBroadcast(nai, DetailedState.DISCONNECTED, type);
+            }
+
+            if (!list.isEmpty() && wasFirstNetwork) {
+                if (DBG) log("Other network available for type " + type +
+                              ", sending connected broadcast");
+                final NetworkAgentInfo replacement = list.get(0);
+                maybeLogBroadcast(replacement, DetailedState.CONNECTED, type,
+                        mService.isDefaultNetwork(replacement));
+                mService.sendLegacyNetworkBroadcast(replacement, DetailedState.CONNECTED, type);
+            }
+        }
+
+        /** Removes the given network from all legacy type lists. */
+        public void remove(NetworkAgentInfo nai, boolean wasDefault) {
+            if (VDBG) log("Removing agent " + nai + " wasDefault=" + wasDefault);
+            for (int type = 0; type < mTypeLists.length; type++) {
+                remove(type, nai, wasDefault);
+            }
+        }
+
+        // send out another legacy broadcast - currently only used for suspend/unsuspend
+        // toggle
+        public void update(NetworkAgentInfo nai) {
+            final boolean isDefault = mService.isDefaultNetwork(nai);
+            final DetailedState state = nai.networkInfo.getDetailedState();
+            for (int type = 0; type < mTypeLists.length; type++) {
+                final ArrayList<NetworkAgentInfo> list = mTypeLists[type];
+                final boolean contains = (list != null && list.contains(nai));
+                final boolean isFirst = contains && (nai == list.get(0));
+                if (isFirst || contains && isDefault) {
+                    maybeLogBroadcast(nai, state, type, isDefault);
+                    mService.sendLegacyNetworkBroadcast(nai, state, type);
+                }
+            }
+        }
+
+        public void dump(IndentingPrintWriter pw) {
+            pw.println("mLegacyTypeTracker:");
+            pw.increaseIndent();
+            pw.print("Supported types:");
+            for (int type = 0; type < mTypeLists.length; type++) {
+                if (mTypeLists[type] != null) pw.print(" " + type);
+            }
+            pw.println();
+            pw.println("Current state:");
+            pw.increaseIndent();
+            synchronized (mTypeLists) {
+                for (int type = 0; type < mTypeLists.length; type++) {
+                    if (mTypeLists[type] == null || mTypeLists[type].isEmpty()) continue;
+                    for (NetworkAgentInfo nai : mTypeLists[type]) {
+                        pw.println(type + " " + nai.toShortString());
+                    }
+                }
+            }
+            pw.decreaseIndent();
+            pw.decreaseIndent();
+            pw.println();
+        }
+    }
+    private final LegacyTypeTracker mLegacyTypeTracker = new LegacyTypeTracker(this);
+
+    final LocalPriorityDump mPriorityDumper = new LocalPriorityDump();
+    /**
+     * Helper class which parses out priority arguments and dumps sections according to their
+     * priority. If priority arguments are omitted, function calls the legacy dump command.
+     */
+    private class LocalPriorityDump {
+        private static final String PRIORITY_ARG = "--dump-priority";
+        private static final String PRIORITY_ARG_HIGH = "HIGH";
+        private static final String PRIORITY_ARG_NORMAL = "NORMAL";
+
+        LocalPriorityDump() {}
+
+        private void dumpHigh(FileDescriptor fd, PrintWriter pw) {
+            doDump(fd, pw, new String[] {DIAG_ARG});
+            doDump(fd, pw, new String[] {SHORT_ARG});
+        }
+
+        private void dumpNormal(FileDescriptor fd, PrintWriter pw, String[] args) {
+            doDump(fd, pw, args);
+        }
+
+        public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
+            if (args == null) {
+                dumpNormal(fd, pw, args);
+                return;
+            }
+
+            String priority = null;
+            for (int argIndex = 0; argIndex < args.length; argIndex++) {
+                if (args[argIndex].equals(PRIORITY_ARG) && argIndex + 1 < args.length) {
+                    argIndex++;
+                    priority = args[argIndex];
+                }
+            }
+
+            if (PRIORITY_ARG_HIGH.equals(priority)) {
+                dumpHigh(fd, pw);
+            } else if (PRIORITY_ARG_NORMAL.equals(priority)) {
+                dumpNormal(fd, pw, args);
+            } else {
+                // ConnectivityService publishes binder service using publishBinderService() with
+                // no priority assigned will be treated as NORMAL priority. Dumpsys does not send
+                // "--dump-priority" arguments to the service. Thus, dump both NORMAL and HIGH to
+                // align the legacy design.
+                // TODO: Integrate into signal dump.
+                dumpNormal(fd, pw, args);
+                pw.println();
+                pw.println("DUMP OF SERVICE HIGH connectivity");
+                pw.println();
+                dumpHigh(fd, pw);
+            }
+        }
+    }
+
+    /**
+     * Keeps track of the number of requests made under different uids.
+     */
+    public static class PerUidCounter {
+        private final int mMaxCountPerUid;
+
+        // Map from UID to number of NetworkRequests that UID has filed.
+        @VisibleForTesting
+        @GuardedBy("mUidToNetworkRequestCount")
+        final SparseIntArray mUidToNetworkRequestCount = new SparseIntArray();
+
+        /**
+         * Constructor
+         *
+         * @param maxCountPerUid the maximum count per uid allowed
+         */
+        public PerUidCounter(final int maxCountPerUid) {
+            mMaxCountPerUid = maxCountPerUid;
+        }
+
+        /**
+         * Increments the request count of the given uid.  Throws an exception if the number
+         * of open requests for the uid exceeds the value of maxCounterPerUid which is the value
+         * passed into the constructor. see: {@link #PerUidCounter(int)}.
+         *
+         * @throws ServiceSpecificException with
+         * {@link ConnectivityManager.Errors.TOO_MANY_REQUESTS} if the number of requests for
+         * the uid exceed the allowed number.
+         *
+         * @param uid the uid that the request was made under
+         */
+        public void incrementCountOrThrow(final int uid) {
+            synchronized (mUidToNetworkRequestCount) {
+                incrementCountOrThrow(uid, 1 /* numToIncrement */);
+            }
+        }
+
+        private void incrementCountOrThrow(final int uid, final int numToIncrement) {
+            final int newRequestCount =
+                    mUidToNetworkRequestCount.get(uid, 0) + numToIncrement;
+            if (newRequestCount >= mMaxCountPerUid) {
+                throw new ServiceSpecificException(
+                        ConnectivityManager.Errors.TOO_MANY_REQUESTS);
+            }
+            mUidToNetworkRequestCount.put(uid, newRequestCount);
+        }
+
+        /**
+         * Decrements the request count of the given uid.
+         *
+         * @param uid the uid that the request was made under
+         */
+        public void decrementCount(final int uid) {
+            synchronized (mUidToNetworkRequestCount) {
+                decrementCount(uid, 1 /* numToDecrement */);
+            }
+        }
+
+        private void decrementCount(final int uid, final int numToDecrement) {
+            final int newRequestCount =
+                    mUidToNetworkRequestCount.get(uid, 0) - numToDecrement;
+            if (newRequestCount < 0) {
+                logwtf("BUG: too small request count " + newRequestCount + " for UID " + uid);
+            } else if (newRequestCount == 0) {
+                mUidToNetworkRequestCount.delete(uid);
+            } else {
+                mUidToNetworkRequestCount.put(uid, newRequestCount);
+            }
+        }
+
+        /**
+         * Used to adjust the request counter for the per-app API flows. Directly adjusting the
+         * counter is not ideal however in the per-app flows, the nris can't be removed until they
+         * are used to create the new nris upon set. Therefore the request count limit can be
+         * artificially hit. This method is used as a workaround for this particular case so that
+         * the request counts are accounted for correctly.
+         * @param uid the uid to adjust counts for
+         * @param numOfNewRequests the new request count to account for
+         * @param r the runnable to execute
+         */
+        public void transact(final int uid, final int numOfNewRequests, @NonNull final Runnable r) {
+            // This should only be used on the handler thread as per all current and foreseen
+            // use-cases. ensureRunningOnConnectivityServiceThread() can't be used because there is
+            // no ref to the outer ConnectivityService.
+            synchronized (mUidToNetworkRequestCount) {
+                final int reqCountOverage = getCallingUidRequestCountOverage(uid, numOfNewRequests);
+                decrementCount(uid, reqCountOverage);
+                r.run();
+                incrementCountOrThrow(uid, reqCountOverage);
+            }
+        }
+
+        private int getCallingUidRequestCountOverage(final int uid, final int numOfNewRequests) {
+            final int newUidRequestCount = mUidToNetworkRequestCount.get(uid, 0)
+                    + numOfNewRequests;
+            return newUidRequestCount >= MAX_NETWORK_REQUESTS_PER_SYSTEM_UID
+                    ? newUidRequestCount - (MAX_NETWORK_REQUESTS_PER_SYSTEM_UID - 1) : 0;
+        }
+    }
+
+    /**
+     * Dependencies of ConnectivityService, for injection in tests.
+     */
+    @VisibleForTesting
+    public static class Dependencies {
+        public int getCallingUid() {
+            return Binder.getCallingUid();
+        }
+
+        /**
+         * Get system properties to use in ConnectivityService.
+         */
+        public MockableSystemProperties getSystemProperties() {
+            return new MockableSystemProperties();
+        }
+
+        /**
+         * Get the {@link ConnectivityResources} to use in ConnectivityService.
+         */
+        public ConnectivityResources getResources(@NonNull Context ctx) {
+            return new ConnectivityResources(ctx);
+        }
+
+        /**
+         * Create a HandlerThread to use in ConnectivityService.
+         */
+        public HandlerThread makeHandlerThread() {
+            return new HandlerThread("ConnectivityServiceThread");
+        }
+
+        /**
+         * Get a reference to the ModuleNetworkStackClient.
+         */
+        public NetworkStackClientBase getNetworkStack() {
+            return ModuleNetworkStackClient.getInstance(null);
+        }
+
+        /**
+         * @see ProxyTracker
+         */
+        public ProxyTracker makeProxyTracker(@NonNull Context context,
+                @NonNull Handler connServiceHandler) {
+            return new ProxyTracker(context, connServiceHandler, EVENT_PROXY_HAS_CHANGED);
+        }
+
+        /**
+         * @see NetIdManager
+         */
+        public NetIdManager makeNetIdManager() {
+            return new NetIdManager();
+        }
+
+        /**
+         * @see NetworkUtils#queryUserAccess(int, int)
+         */
+        public boolean queryUserAccess(int uid, Network network, ConnectivityService cs) {
+            return cs.queryUserAccess(uid, network);
+        }
+
+        /**
+         * Gets the UID that owns a socket connection. Needed because opening SOCK_DIAG sockets
+         * requires CAP_NET_ADMIN, which the unit tests do not have.
+         */
+        public int getConnectionOwnerUid(int protocol, InetSocketAddress local,
+                InetSocketAddress remote) {
+            return InetDiagMessage.getConnectionOwnerUid(protocol, local, remote);
+        }
+
+        /**
+         * @see MultinetworkPolicyTracker
+         */
+        public MultinetworkPolicyTracker makeMultinetworkPolicyTracker(
+                @NonNull Context c, @NonNull Handler h, @NonNull Runnable r) {
+            return new MultinetworkPolicyTracker(c, h, r);
+        }
+
+        /**
+         * @see BatteryStatsManager
+         */
+        public void reportNetworkInterfaceForTransports(Context context, String iface,
+                int[] transportTypes) {
+            final BatteryStatsManager batteryStats =
+                    context.getSystemService(BatteryStatsManager.class);
+            batteryStats.reportNetworkInterfaceForTransports(iface, transportTypes);
+        }
+
+        public boolean getCellular464XlatEnabled() {
+            return NetworkProperties.isCellular464XlatEnabled().orElse(true);
+        }
+    }
+
+    public ConnectivityService(Context context) {
+        this(context, getDnsResolver(context), new IpConnectivityLog(),
+                INetd.Stub.asInterface((IBinder) context.getSystemService(Context.NETD_SERVICE)),
+                new Dependencies());
+    }
+
+    @VisibleForTesting
+    protected ConnectivityService(Context context, IDnsResolver dnsresolver,
+            IpConnectivityLog logger, INetd netd, Dependencies deps) {
+        if (DBG) log("ConnectivityService starting up");
+
+        mDeps = Objects.requireNonNull(deps, "missing Dependencies");
+        mSystemProperties = mDeps.getSystemProperties();
+        mNetIdManager = mDeps.makeNetIdManager();
+        mContext = Objects.requireNonNull(context, "missing Context");
+        mResources = deps.getResources(mContext);
+        mNetworkRequestCounter = new PerUidCounter(MAX_NETWORK_REQUESTS_PER_UID);
+        mSystemNetworkRequestCounter = new PerUidCounter(MAX_NETWORK_REQUESTS_PER_SYSTEM_UID);
+
+        mMetricsLog = logger;
+        mNetworkRanker = new NetworkRanker();
+        final NetworkRequest defaultInternetRequest = createDefaultRequest();
+        mDefaultRequest = new NetworkRequestInfo(
+                Process.myUid(), defaultInternetRequest, null,
+                new Binder(), NetworkCallback.FLAG_INCLUDE_LOCATION_INFO,
+                null /* attributionTags */);
+        mNetworkRequests.put(defaultInternetRequest, mDefaultRequest);
+        mDefaultNetworkRequests.add(mDefaultRequest);
+        mNetworkRequestInfoLogs.log("REGISTER " + mDefaultRequest);
+
+        mDefaultMobileDataRequest = createDefaultInternetRequestForTransport(
+                NetworkCapabilities.TRANSPORT_CELLULAR, NetworkRequest.Type.BACKGROUND_REQUEST);
+
+        // The default WiFi request is a background request so that apps using WiFi are
+        // migrated to a better network (typically ethernet) when one comes up, instead
+        // of staying on WiFi forever.
+        mDefaultWifiRequest = createDefaultInternetRequestForTransport(
+                NetworkCapabilities.TRANSPORT_WIFI, NetworkRequest.Type.BACKGROUND_REQUEST);
+
+        mDefaultVehicleRequest = createAlwaysOnRequestForCapability(
+                NetworkCapabilities.NET_CAPABILITY_VEHICLE_INTERNAL,
+                NetworkRequest.Type.BACKGROUND_REQUEST);
+
+        mHandlerThread = mDeps.makeHandlerThread();
+        mHandlerThread.start();
+        mHandler = new InternalHandler(mHandlerThread.getLooper());
+        mTrackerHandler = new NetworkStateTrackerHandler(mHandlerThread.getLooper());
+        mConnectivityDiagnosticsHandler =
+                new ConnectivityDiagnosticsHandler(mHandlerThread.getLooper());
+
+        mReleasePendingIntentDelayMs = Settings.Secure.getInt(context.getContentResolver(),
+                ConnectivitySettingsManager.CONNECTIVITY_RELEASE_PENDING_INTENT_DELAY_MS, 5_000);
+
+        mLingerDelayMs = mSystemProperties.getInt(LINGER_DELAY_PROPERTY, DEFAULT_LINGER_DELAY_MS);
+        // TODO: Consider making the timer customizable.
+        mNascentDelayMs = DEFAULT_NASCENT_DELAY_MS;
+
+        mStatsManager = mContext.getSystemService(NetworkStatsManager.class);
+        mPolicyManager = mContext.getSystemService(NetworkPolicyManager.class);
+        mDnsResolver = Objects.requireNonNull(dnsresolver, "missing IDnsResolver");
+        mProxyTracker = mDeps.makeProxyTracker(mContext, mHandler);
+
+        mNetd = netd;
+        mTelephonyManager = (TelephonyManager) mContext.getSystemService(Context.TELEPHONY_SERVICE);
+        mAppOpsManager = (AppOpsManager) mContext.getSystemService(Context.APP_OPS_SERVICE);
+        mLocationPermissionChecker = new LocationPermissionChecker(mContext);
+
+        // To ensure uid state is synchronized with Network Policy, register for
+        // NetworkPolicyManagerService events must happen prior to NetworkPolicyManagerService
+        // reading existing policy from disk.
+        mPolicyManager.registerNetworkPolicyCallback(null, mPolicyCallback);
+
+        final PowerManager powerManager = (PowerManager) context.getSystemService(
+                Context.POWER_SERVICE);
+        mNetTransitionWakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, TAG);
+        mPendingIntentWakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, TAG);
+
+        mLegacyTypeTracker.loadSupportedTypes(mContext, mTelephonyManager);
+        mProtectedNetworks = new ArrayList<>();
+        int[] protectedNetworks = mResources.get().getIntArray(R.array.config_protectedNetworks);
+        for (int p : protectedNetworks) {
+            if (mLegacyTypeTracker.isTypeSupported(p) && !mProtectedNetworks.contains(p)) {
+                mProtectedNetworks.add(p);
+            } else {
+                if (DBG) loge("Ignoring protectedNetwork " + p);
+            }
+        }
+
+        mUserManager = (UserManager) context.getSystemService(Context.USER_SERVICE);
+
+        mPermissionMonitor = new PermissionMonitor(mContext, mNetd);
+
+        mUserAllContext = mContext.createContextAsUser(UserHandle.ALL, 0 /* flags */);
+        // Listen for user add/removes to inform PermissionMonitor.
+        // Should run on mHandler to avoid any races.
+        final IntentFilter userIntentFilter = new IntentFilter();
+        userIntentFilter.addAction(Intent.ACTION_USER_ADDED);
+        userIntentFilter.addAction(Intent.ACTION_USER_REMOVED);
+        mUserAllContext.registerReceiver(mUserIntentReceiver, userIntentFilter,
+                null /* broadcastPermission */, mHandler);
+
+        // Listen to package add/removes for netd
+        final IntentFilter packageIntentFilter = new IntentFilter();
+        packageIntentFilter.addAction(Intent.ACTION_PACKAGE_ADDED);
+        packageIntentFilter.addAction(Intent.ACTION_PACKAGE_REMOVED);
+        packageIntentFilter.addAction(Intent.ACTION_PACKAGE_REPLACED);
+        packageIntentFilter.addDataScheme("package");
+        mUserAllContext.registerReceiver(mPackageIntentReceiver, packageIntentFilter,
+                null /* broadcastPermission */, mHandler);
+
+        mNetworkActivityTracker = new LegacyNetworkActivityTracker(mContext, mHandler, mNetd);
+
+        mNetdCallback = new NetdCallback();
+        try {
+            mNetd.registerUnsolicitedEventListener(mNetdCallback);
+        } catch (RemoteException | ServiceSpecificException e) {
+            loge("Error registering event listener :" + e);
+        }
+
+        mSettingsObserver = new SettingsObserver(mContext, mHandler);
+        registerSettingsCallbacks();
+
+        mKeepaliveTracker = new KeepaliveTracker(mContext, mHandler);
+        mNotifier = new NetworkNotificationManager(mContext, mTelephonyManager);
+        mQosCallbackTracker = new QosCallbackTracker(mHandler, mNetworkRequestCounter);
+
+        final int dailyLimit = Settings.Global.getInt(mContext.getContentResolver(),
+                ConnectivitySettingsManager.NETWORK_SWITCH_NOTIFICATION_DAILY_LIMIT,
+                LingerMonitor.DEFAULT_NOTIFICATION_DAILY_LIMIT);
+        final long rateLimit = Settings.Global.getLong(mContext.getContentResolver(),
+                ConnectivitySettingsManager.NETWORK_SWITCH_NOTIFICATION_RATE_LIMIT_MILLIS,
+                LingerMonitor.DEFAULT_NOTIFICATION_RATE_LIMIT_MILLIS);
+        mLingerMonitor = new LingerMonitor(mContext, mNotifier, dailyLimit, rateLimit);
+
+        mMultinetworkPolicyTracker = mDeps.makeMultinetworkPolicyTracker(
+                mContext, mHandler, () -> updateAvoidBadWifi());
+        mMultinetworkPolicyTracker.start();
+
+        mDnsManager = new DnsManager(mContext, mDnsResolver);
+        registerPrivateDnsSettingsCallbacks();
+
+        // This NAI is a sentinel used to offer no service to apps that are on a multi-layer
+        // request that doesn't allow fallback to the default network. It should never be visible
+        // to apps. As such, it's not in the list of NAIs and doesn't need many of the normal
+        // arguments like the handler or the DnsResolver.
+        // TODO : remove this ; it is probably better handled with a sentinel request.
+        mNoServiceNetwork = new NetworkAgentInfo(null,
+                new Network(NO_SERVICE_NET_ID),
+                new NetworkInfo(TYPE_NONE, 0, "", ""),
+                new LinkProperties(), new NetworkCapabilities(),
+                new NetworkScore.Builder().setLegacyInt(0).build(), mContext, null,
+                new NetworkAgentConfig(), this, null, null, 0, INVALID_UID,
+                mLingerDelayMs, mQosCallbackTracker, mDeps);
+    }
+
+    private static NetworkCapabilities createDefaultNetworkCapabilitiesForUid(int uid) {
+        return createDefaultNetworkCapabilitiesForUidRange(new UidRange(uid, uid));
+    }
+
+    private static NetworkCapabilities createDefaultNetworkCapabilitiesForUidRange(
+            @NonNull final UidRange uids) {
+        final NetworkCapabilities netCap = new NetworkCapabilities();
+        netCap.addCapability(NET_CAPABILITY_INTERNET);
+        netCap.addCapability(NET_CAPABILITY_NOT_VCN_MANAGED);
+        netCap.removeCapability(NET_CAPABILITY_NOT_VPN);
+        netCap.setUids(UidRange.toIntRanges(Collections.singleton(uids)));
+        return netCap;
+    }
+
+    private NetworkRequest createDefaultRequest() {
+        return createDefaultInternetRequestForTransport(
+                TYPE_NONE, NetworkRequest.Type.REQUEST);
+    }
+
+    private NetworkRequest createDefaultInternetRequestForTransport(
+            int transportType, NetworkRequest.Type type) {
+        final NetworkCapabilities netCap = new NetworkCapabilities();
+        netCap.addCapability(NET_CAPABILITY_INTERNET);
+        netCap.addCapability(NET_CAPABILITY_NOT_VCN_MANAGED);
+        netCap.setRequestorUidAndPackageName(Process.myUid(), mContext.getPackageName());
+        if (transportType > TYPE_NONE) {
+            netCap.addTransportType(transportType);
+        }
+        return createNetworkRequest(type, netCap);
+    }
+
+    private NetworkRequest createNetworkRequest(
+            NetworkRequest.Type type, NetworkCapabilities netCap) {
+        return new NetworkRequest(netCap, TYPE_NONE, nextNetworkRequestId(), type);
+    }
+
+    private NetworkRequest createAlwaysOnRequestForCapability(int capability,
+            NetworkRequest.Type type) {
+        final NetworkCapabilities netCap = new NetworkCapabilities();
+        netCap.clearAll();
+        netCap.addCapability(capability);
+        netCap.setRequestorUidAndPackageName(Process.myUid(), mContext.getPackageName());
+        return new NetworkRequest(netCap, TYPE_NONE, nextNetworkRequestId(), type);
+    }
+
+    // Used only for testing.
+    // TODO: Delete this and either:
+    // 1. Give FakeSettingsProvider the ability to send settings change notifications (requires
+    //    changing ContentResolver to make registerContentObserver non-final).
+    // 2. Give FakeSettingsProvider an alternative notification mechanism and have the test use it
+    //    by subclassing SettingsObserver.
+    @VisibleForTesting
+    void updateAlwaysOnNetworks() {
+        mHandler.sendEmptyMessage(EVENT_CONFIGURE_ALWAYS_ON_NETWORKS);
+    }
+
+    // See FakeSettingsProvider comment above.
+    @VisibleForTesting
+    void updatePrivateDnsSettings() {
+        mHandler.sendEmptyMessage(EVENT_PRIVATE_DNS_SETTINGS_CHANGED);
+    }
+
+    private void handleAlwaysOnNetworkRequest(NetworkRequest networkRequest, int id) {
+        final boolean enable = mContext.getResources().getBoolean(id);
+        handleAlwaysOnNetworkRequest(networkRequest, enable);
+    }
+
+    private void handleAlwaysOnNetworkRequest(
+            NetworkRequest networkRequest, String settingName, boolean defaultValue) {
+        final boolean enable = toBool(Settings.Global.getInt(
+                mContext.getContentResolver(), settingName, encodeBool(defaultValue)));
+        handleAlwaysOnNetworkRequest(networkRequest, enable);
+    }
+
+    private void handleAlwaysOnNetworkRequest(NetworkRequest networkRequest, boolean enable) {
+        final boolean isEnabled = (mNetworkRequests.get(networkRequest) != null);
+        if (enable == isEnabled) {
+            return;  // Nothing to do.
+        }
+
+        if (enable) {
+            handleRegisterNetworkRequest(new NetworkRequestInfo(
+                    Process.myUid(), networkRequest, null, new Binder(),
+                    NetworkCallback.FLAG_INCLUDE_LOCATION_INFO,
+                    null /* attributionTags */));
+        } else {
+            handleReleaseNetworkRequest(networkRequest, Process.SYSTEM_UID,
+                    /* callOnUnavailable */ false);
+        }
+    }
+
+    private void handleConfigureAlwaysOnNetworks() {
+        handleAlwaysOnNetworkRequest(mDefaultMobileDataRequest,
+                ConnectivitySettingsManager.MOBILE_DATA_ALWAYS_ON, true /* defaultValue */);
+        handleAlwaysOnNetworkRequest(mDefaultWifiRequest,
+                ConnectivitySettingsManager.WIFI_ALWAYS_REQUESTED, false /* defaultValue */);
+        final boolean vehicleAlwaysRequested = mResources.get().getBoolean(
+                R.bool.config_vehicleInternalNetworkAlwaysRequested);
+        // TODO (b/183076074): remove legacy fallback after migrating overlays
+        final boolean legacyAlwaysRequested = mContext.getResources().getBoolean(
+                mContext.getResources().getIdentifier(
+                        "config_vehicleInternalNetworkAlwaysRequested", "bool", "android"));
+        handleAlwaysOnNetworkRequest(mDefaultVehicleRequest,
+                vehicleAlwaysRequested || legacyAlwaysRequested);
+    }
+
+    private void registerSettingsCallbacks() {
+        // Watch for global HTTP proxy changes.
+        mSettingsObserver.observe(
+                Settings.Global.getUriFor(Settings.Global.HTTP_PROXY),
+                EVENT_APPLY_GLOBAL_HTTP_PROXY);
+
+        // Watch for whether or not to keep mobile data always on.
+        mSettingsObserver.observe(
+                Settings.Global.getUriFor(ConnectivitySettingsManager.MOBILE_DATA_ALWAYS_ON),
+                EVENT_CONFIGURE_ALWAYS_ON_NETWORKS);
+
+        // Watch for whether or not to keep wifi always on.
+        mSettingsObserver.observe(
+                Settings.Global.getUriFor(ConnectivitySettingsManager.WIFI_ALWAYS_REQUESTED),
+                EVENT_CONFIGURE_ALWAYS_ON_NETWORKS);
+    }
+
+    private void registerPrivateDnsSettingsCallbacks() {
+        for (Uri uri : DnsManager.getPrivateDnsSettingsUris()) {
+            mSettingsObserver.observe(uri, EVENT_PRIVATE_DNS_SETTINGS_CHANGED);
+        }
+    }
+
+    private synchronized int nextNetworkRequestId() {
+        // TODO: Consider handle wrapping and exclude {@link NetworkRequest#REQUEST_ID_NONE} if
+        //  doing that.
+        return mNextNetworkRequestId++;
+    }
+
+    @VisibleForTesting
+    protected NetworkAgentInfo getNetworkAgentInfoForNetwork(Network network) {
+        if (network == null) {
+            return null;
+        }
+        return getNetworkAgentInfoForNetId(network.getNetId());
+    }
+
+    private NetworkAgentInfo getNetworkAgentInfoForNetId(int netId) {
+        synchronized (mNetworkForNetId) {
+            return mNetworkForNetId.get(netId);
+        }
+    }
+
+    // TODO: determine what to do when more than one VPN applies to |uid|.
+    private NetworkAgentInfo getVpnForUid(int uid) {
+        synchronized (mNetworkForNetId) {
+            for (int i = 0; i < mNetworkForNetId.size(); i++) {
+                final NetworkAgentInfo nai = mNetworkForNetId.valueAt(i);
+                if (nai.isVPN() && nai.everConnected && nai.networkCapabilities.appliesToUid(uid)) {
+                    return nai;
+                }
+            }
+        }
+        return null;
+    }
+
+    private Network[] getVpnUnderlyingNetworks(int uid) {
+        if (mLockdownEnabled) return null;
+        final NetworkAgentInfo nai = getVpnForUid(uid);
+        if (nai != null) return nai.declaredUnderlyingNetworks;
+        return null;
+    }
+
+    private NetworkAgentInfo getNetworkAgentInfoForUid(int uid) {
+        NetworkAgentInfo nai = getDefaultNetworkForUid(uid);
+
+        final Network[] networks = getVpnUnderlyingNetworks(uid);
+        if (networks != null) {
+            // getUnderlyingNetworks() returns:
+            // null => there was no VPN, or the VPN didn't specify anything, so we use the default.
+            // empty array => the VPN explicitly said "no default network".
+            // non-empty array => the VPN specified one or more default networks; we use the
+            //                    first one.
+            if (networks.length > 0) {
+                nai = getNetworkAgentInfoForNetwork(networks[0]);
+            } else {
+                nai = null;
+            }
+        }
+        return nai;
+    }
+
+    /**
+     * Check if UID should be blocked from using the specified network.
+     */
+    private boolean isNetworkWithCapabilitiesBlocked(@Nullable final NetworkCapabilities nc,
+            final int uid, final boolean ignoreBlocked) {
+        // Networks aren't blocked when ignoring blocked status
+        if (ignoreBlocked) {
+            return false;
+        }
+        if (isUidBlockedByVpn(uid, mVpnBlockedUidRanges)) return true;
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            final boolean metered = nc == null ? true : nc.isMetered();
+            return mPolicyManager.isUidNetworkingBlocked(uid, metered);
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+    }
+
+    private void maybeLogBlockedNetworkInfo(NetworkInfo ni, int uid) {
+        if (ni == null || !LOGD_BLOCKED_NETWORKINFO) {
+            return;
+        }
+        final boolean blocked;
+        synchronized (mBlockedAppUids) {
+            if (ni.getDetailedState() == DetailedState.BLOCKED && mBlockedAppUids.add(uid)) {
+                blocked = true;
+            } else if (ni.isConnected() && mBlockedAppUids.remove(uid)) {
+                blocked = false;
+            } else {
+                return;
+            }
+        }
+        String action = blocked ? "BLOCKED" : "UNBLOCKED";
+        log(String.format("Returning %s NetworkInfo to uid=%d", action, uid));
+        mNetworkInfoBlockingLogs.log(action + " " + uid);
+    }
+
+    private void maybeLogBlockedStatusChanged(NetworkRequestInfo nri, Network net, int blocked) {
+        if (nri == null || net == null || !LOGD_BLOCKED_NETWORKINFO) {
+            return;
+        }
+        final String action = (blocked != 0) ? "BLOCKED" : "UNBLOCKED";
+        final int requestId = nri.getActiveRequest() != null
+                ? nri.getActiveRequest().requestId : nri.mRequests.get(0).requestId;
+        mNetworkInfoBlockingLogs.log(String.format(
+                "%s %d(%d) on netId %d: %s", action, nri.mAsUid, requestId, net.getNetId(),
+                Integer.toHexString(blocked)));
+    }
+
+    /**
+     * Apply any relevant filters to the specified {@link NetworkInfo} for the given UID. For
+     * example, this may mark the network as {@link DetailedState#BLOCKED} based
+     * on {@link #isNetworkWithCapabilitiesBlocked}.
+     */
+    @NonNull
+    private NetworkInfo filterNetworkInfo(@NonNull NetworkInfo networkInfo, int type,
+            @NonNull NetworkCapabilities nc, int uid, boolean ignoreBlocked) {
+        final NetworkInfo filtered = new NetworkInfo(networkInfo);
+        // Many legacy types (e.g,. TYPE_MOBILE_HIPRI) are not actually a property of the network
+        // but only exists if an app asks about them or requests them. Ensure the requesting app
+        // gets the type it asks for.
+        filtered.setType(type);
+        if (isNetworkWithCapabilitiesBlocked(nc, uid, ignoreBlocked)) {
+            filtered.setDetailedState(DetailedState.BLOCKED, null /* reason */,
+                    null /* extraInfo */);
+        }
+        filterForLegacyLockdown(filtered);
+        return filtered;
+    }
+
+    private NetworkInfo getFilteredNetworkInfo(NetworkAgentInfo nai, int uid,
+            boolean ignoreBlocked) {
+        return filterNetworkInfo(nai.networkInfo, nai.networkInfo.getType(),
+                nai.networkCapabilities, uid, ignoreBlocked);
+    }
+
+    /**
+     * Return NetworkInfo for the active (i.e., connected) network interface.
+     * It is assumed that at most one network is active at a time. If more
+     * than one is active, it is indeterminate which will be returned.
+     * @return the info for the active network, or {@code null} if none is
+     * active
+     */
+    @Override
+    public NetworkInfo getActiveNetworkInfo() {
+        enforceAccessPermission();
+        final int uid = mDeps.getCallingUid();
+        final NetworkAgentInfo nai = getNetworkAgentInfoForUid(uid);
+        if (nai == null) return null;
+        final NetworkInfo networkInfo = getFilteredNetworkInfo(nai, uid, false);
+        maybeLogBlockedNetworkInfo(networkInfo, uid);
+        return networkInfo;
+    }
+
+    @Override
+    public Network getActiveNetwork() {
+        enforceAccessPermission();
+        return getActiveNetworkForUidInternal(mDeps.getCallingUid(), false);
+    }
+
+    @Override
+    public Network getActiveNetworkForUid(int uid, boolean ignoreBlocked) {
+        PermissionUtils.enforceNetworkStackPermission(mContext);
+        return getActiveNetworkForUidInternal(uid, ignoreBlocked);
+    }
+
+    private Network getActiveNetworkForUidInternal(final int uid, boolean ignoreBlocked) {
+        final NetworkAgentInfo vpnNai = getVpnForUid(uid);
+        if (vpnNai != null) {
+            final NetworkCapabilities requiredCaps = createDefaultNetworkCapabilitiesForUid(uid);
+            if (requiredCaps.satisfiedByNetworkCapabilities(vpnNai.networkCapabilities)) {
+                return vpnNai.network;
+            }
+        }
+
+        NetworkAgentInfo nai = getDefaultNetworkForUid(uid);
+        if (nai == null || isNetworkWithCapabilitiesBlocked(nai.networkCapabilities, uid,
+                ignoreBlocked)) {
+            return null;
+        }
+        return nai.network;
+    }
+
+    @Override
+    public NetworkInfo getActiveNetworkInfoForUid(int uid, boolean ignoreBlocked) {
+        PermissionUtils.enforceNetworkStackPermission(mContext);
+        final NetworkAgentInfo nai = getNetworkAgentInfoForUid(uid);
+        if (nai == null) return null;
+        return getFilteredNetworkInfo(nai, uid, ignoreBlocked);
+    }
+
+    /** Returns a NetworkInfo object for a network that doesn't exist. */
+    private NetworkInfo makeFakeNetworkInfo(int networkType, int uid) {
+        final NetworkInfo info = new NetworkInfo(networkType, 0 /* subtype */,
+                getNetworkTypeName(networkType), "" /* subtypeName */);
+        info.setIsAvailable(true);
+        // For compatibility with legacy code, return BLOCKED instead of DISCONNECTED when
+        // background data is restricted.
+        final NetworkCapabilities nc = new NetworkCapabilities();  // Metered.
+        final DetailedState state = isNetworkWithCapabilitiesBlocked(nc, uid, false)
+                ? DetailedState.BLOCKED
+                : DetailedState.DISCONNECTED;
+        info.setDetailedState(state, null /* reason */, null /* extraInfo */);
+        filterForLegacyLockdown(info);
+        return info;
+    }
+
+    private NetworkInfo getFilteredNetworkInfoForType(int networkType, int uid) {
+        if (!mLegacyTypeTracker.isTypeSupported(networkType)) {
+            return null;
+        }
+        final NetworkAgentInfo nai = mLegacyTypeTracker.getNetworkForType(networkType);
+        if (nai == null) {
+            return makeFakeNetworkInfo(networkType, uid);
+        }
+        return filterNetworkInfo(nai.networkInfo, networkType, nai.networkCapabilities, uid,
+                false);
+    }
+
+    @Override
+    public NetworkInfo getNetworkInfo(int networkType) {
+        enforceAccessPermission();
+        final int uid = mDeps.getCallingUid();
+        if (getVpnUnderlyingNetworks(uid) != null) {
+            // A VPN is active, so we may need to return one of its underlying networks. This
+            // information is not available in LegacyTypeTracker, so we have to get it from
+            // getNetworkAgentInfoForUid.
+            final NetworkAgentInfo nai = getNetworkAgentInfoForUid(uid);
+            if (nai == null) return null;
+            final NetworkInfo networkInfo = getFilteredNetworkInfo(nai, uid, false);
+            if (networkInfo.getType() == networkType) {
+                return networkInfo;
+            }
+        }
+        return getFilteredNetworkInfoForType(networkType, uid);
+    }
+
+    @Override
+    public NetworkInfo getNetworkInfoForUid(Network network, int uid, boolean ignoreBlocked) {
+        enforceAccessPermission();
+        final NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+        if (nai == null) return null;
+        return getFilteredNetworkInfo(nai, uid, ignoreBlocked);
+    }
+
+    @Override
+    public NetworkInfo[] getAllNetworkInfo() {
+        enforceAccessPermission();
+        final ArrayList<NetworkInfo> result = new ArrayList<>();
+        for (int networkType = 0; networkType <= ConnectivityManager.MAX_NETWORK_TYPE;
+                networkType++) {
+            NetworkInfo info = getNetworkInfo(networkType);
+            if (info != null) {
+                result.add(info);
+            }
+        }
+        return result.toArray(new NetworkInfo[result.size()]);
+    }
+
+    @Override
+    public Network getNetworkForType(int networkType) {
+        enforceAccessPermission();
+        if (!mLegacyTypeTracker.isTypeSupported(networkType)) {
+            return null;
+        }
+        final NetworkAgentInfo nai = mLegacyTypeTracker.getNetworkForType(networkType);
+        if (nai == null) {
+            return null;
+        }
+        final int uid = mDeps.getCallingUid();
+        if (isNetworkWithCapabilitiesBlocked(nai.networkCapabilities, uid, false)) {
+            return null;
+        }
+        return nai.network;
+    }
+
+    @Override
+    public Network[] getAllNetworks() {
+        enforceAccessPermission();
+        synchronized (mNetworkForNetId) {
+            final Network[] result = new Network[mNetworkForNetId.size()];
+            for (int i = 0; i < mNetworkForNetId.size(); i++) {
+                result[i] = mNetworkForNetId.valueAt(i).network;
+            }
+            return result;
+        }
+    }
+
+    @Override
+    public NetworkCapabilities[] getDefaultNetworkCapabilitiesForUser(
+                int userId, String callingPackageName, @Nullable String callingAttributionTag) {
+        // The basic principle is: if an app's traffic could possibly go over a
+        // network, without the app doing anything multinetwork-specific,
+        // (hence, by "default"), then include that network's capabilities in
+        // the array.
+        //
+        // In the normal case, app traffic only goes over the system's default
+        // network connection, so that's the only network returned.
+        //
+        // With a VPN in force, some app traffic may go into the VPN, and thus
+        // over whatever underlying networks the VPN specifies, while other app
+        // traffic may go over the system default network (e.g.: a split-tunnel
+        // VPN, or an app disallowed by the VPN), so the set of networks
+        // returned includes the VPN's underlying networks and the system
+        // default.
+        enforceAccessPermission();
+
+        HashMap<Network, NetworkCapabilities> result = new HashMap<>();
+
+        for (final NetworkRequestInfo nri : mDefaultNetworkRequests) {
+            if (!nri.isBeingSatisfied()) {
+                continue;
+            }
+            final NetworkAgentInfo nai = nri.getSatisfier();
+            final NetworkCapabilities nc = getNetworkCapabilitiesInternal(nai);
+            if (null != nc
+                    && nc.hasCapability(NET_CAPABILITY_NOT_RESTRICTED)
+                    && !result.containsKey(nai.network)) {
+                result.put(
+                        nai.network,
+                        createWithLocationInfoSanitizedIfNecessaryWhenParceled(
+                                nc, false /* includeLocationSensitiveInfo */,
+                                getCallingPid(), mDeps.getCallingUid(), callingPackageName,
+                                callingAttributionTag));
+            }
+        }
+
+        // No need to check mLockdownEnabled. If it's true, getVpnUnderlyingNetworks returns null.
+        final Network[] networks = getVpnUnderlyingNetworks(mDeps.getCallingUid());
+        if (null != networks) {
+            for (final Network network : networks) {
+                final NetworkCapabilities nc = getNetworkCapabilitiesInternal(network);
+                if (null != nc) {
+                    result.put(
+                            network,
+                            createWithLocationInfoSanitizedIfNecessaryWhenParceled(
+                                    nc,
+                                    false /* includeLocationSensitiveInfo */,
+                                    getCallingPid(), mDeps.getCallingUid(), callingPackageName,
+                                    callingAttributionTag));
+                }
+            }
+        }
+
+        NetworkCapabilities[] out = new NetworkCapabilities[result.size()];
+        out = result.values().toArray(out);
+        return out;
+    }
+
+    @Override
+    public boolean isNetworkSupported(int networkType) {
+        enforceAccessPermission();
+        return mLegacyTypeTracker.isTypeSupported(networkType);
+    }
+
+    /**
+     * Return LinkProperties for the active (i.e., connected) default
+     * network interface for the calling uid.
+     * @return the ip properties for the active network, or {@code null} if
+     * none is active
+     */
+    @Override
+    public LinkProperties getActiveLinkProperties() {
+        enforceAccessPermission();
+        final int uid = mDeps.getCallingUid();
+        NetworkAgentInfo nai = getNetworkAgentInfoForUid(uid);
+        if (nai == null) return null;
+        return linkPropertiesRestrictedForCallerPermissions(nai.linkProperties,
+                Binder.getCallingPid(), uid);
+    }
+
+    @Override
+    public LinkProperties getLinkPropertiesForType(int networkType) {
+        enforceAccessPermission();
+        NetworkAgentInfo nai = mLegacyTypeTracker.getNetworkForType(networkType);
+        final LinkProperties lp = getLinkProperties(nai);
+        if (lp == null) return null;
+        return linkPropertiesRestrictedForCallerPermissions(
+                lp, Binder.getCallingPid(), mDeps.getCallingUid());
+    }
+
+    // TODO - this should be ALL networks
+    @Override
+    public LinkProperties getLinkProperties(Network network) {
+        enforceAccessPermission();
+        final LinkProperties lp = getLinkProperties(getNetworkAgentInfoForNetwork(network));
+        if (lp == null) return null;
+        return linkPropertiesRestrictedForCallerPermissions(
+                lp, Binder.getCallingPid(), mDeps.getCallingUid());
+    }
+
+    @Nullable
+    private LinkProperties getLinkProperties(@Nullable NetworkAgentInfo nai) {
+        if (nai == null) {
+            return null;
+        }
+        synchronized (nai) {
+            return nai.linkProperties;
+        }
+    }
+
+    private NetworkCapabilities getNetworkCapabilitiesInternal(Network network) {
+        return getNetworkCapabilitiesInternal(getNetworkAgentInfoForNetwork(network));
+    }
+
+    private NetworkCapabilities getNetworkCapabilitiesInternal(NetworkAgentInfo nai) {
+        if (nai == null) return null;
+        synchronized (nai) {
+            return networkCapabilitiesRestrictedForCallerPermissions(
+                    nai.networkCapabilities, Binder.getCallingPid(), mDeps.getCallingUid());
+        }
+    }
+
+    @Override
+    public NetworkCapabilities getNetworkCapabilities(Network network, String callingPackageName,
+            @Nullable String callingAttributionTag) {
+        mAppOpsManager.checkPackage(mDeps.getCallingUid(), callingPackageName);
+        enforceAccessPermission();
+        return createWithLocationInfoSanitizedIfNecessaryWhenParceled(
+                getNetworkCapabilitiesInternal(network),
+                false /* includeLocationSensitiveInfo */,
+                getCallingPid(), mDeps.getCallingUid(), callingPackageName, callingAttributionTag);
+    }
+
+    @VisibleForTesting
+    NetworkCapabilities networkCapabilitiesRestrictedForCallerPermissions(
+            NetworkCapabilities nc, int callerPid, int callerUid) {
+        final NetworkCapabilities newNc = new NetworkCapabilities(nc);
+        if (!checkSettingsPermission(callerPid, callerUid)) {
+            newNc.setUids(null);
+            newNc.setSSID(null);
+        }
+        if (newNc.getNetworkSpecifier() != null) {
+            newNc.setNetworkSpecifier(newNc.getNetworkSpecifier().redact());
+        }
+        newNc.setAdministratorUids(new int[0]);
+        if (!checkAnyPermissionOf(
+                callerPid, callerUid, android.Manifest.permission.NETWORK_FACTORY)) {
+            newNc.setSubscriptionIds(Collections.emptySet());
+        }
+
+        return newNc;
+    }
+
+    /**
+     * Wrapper used to cache the permission check results performed for the corresponding
+     * app. This avoid performing multiple permission checks for different fields in
+     * NetworkCapabilities.
+     * Note: This wrapper does not support any sort of invalidation and thus must not be
+     * persistent or long-lived. It may only be used for the time necessary to
+     * compute the redactions required by one particular NetworkCallback or
+     * synchronous call.
+     */
+    private class RedactionPermissionChecker {
+        private final int mCallingPid;
+        private final int mCallingUid;
+        @NonNull private final String mCallingPackageName;
+        @Nullable private final String mCallingAttributionTag;
+
+        private Boolean mHasLocationPermission = null;
+        private Boolean mHasLocalMacAddressPermission = null;
+        private Boolean mHasSettingsPermission = null;
+
+        RedactionPermissionChecker(int callingPid, int callingUid,
+                @NonNull String callingPackageName, @Nullable String callingAttributionTag) {
+            mCallingPid = callingPid;
+            mCallingUid = callingUid;
+            mCallingPackageName = callingPackageName;
+            mCallingAttributionTag = callingAttributionTag;
+        }
+
+        private boolean hasLocationPermissionInternal() {
+            final long token = Binder.clearCallingIdentity();
+            try {
+                return mLocationPermissionChecker.checkLocationPermission(
+                        mCallingPackageName, mCallingAttributionTag, mCallingUid,
+                        null /* message */);
+            } finally {
+                Binder.restoreCallingIdentity(token);
+            }
+        }
+
+        /**
+         * Returns whether the app holds location permission or not (might return cached result
+         * if the permission was already checked before).
+         */
+        public boolean hasLocationPermission() {
+            if (mHasLocationPermission == null) {
+                // If there is no cached result, perform the check now.
+                mHasLocationPermission = hasLocationPermissionInternal();
+            }
+            return mHasLocationPermission;
+        }
+
+        /**
+         * Returns whether the app holds local mac address permission or not (might return cached
+         * result if the permission was already checked before).
+         */
+        public boolean hasLocalMacAddressPermission() {
+            if (mHasLocalMacAddressPermission == null) {
+                // If there is no cached result, perform the check now.
+                mHasLocalMacAddressPermission =
+                        checkLocalMacAddressPermission(mCallingPid, mCallingUid);
+            }
+            return mHasLocalMacAddressPermission;
+        }
+
+        /**
+         * Returns whether the app holds settings permission or not (might return cached
+         * result if the permission was already checked before).
+         */
+        public boolean hasSettingsPermission() {
+            if (mHasSettingsPermission == null) {
+                // If there is no cached result, perform the check now.
+                mHasSettingsPermission = checkSettingsPermission(mCallingPid, mCallingUid);
+            }
+            return mHasSettingsPermission;
+        }
+    }
+
+    private static boolean shouldRedact(@NetworkCapabilities.RedactionType long redactions,
+            @NetworkCapabilities.NetCapability long redaction) {
+        return (redactions & redaction) != 0;
+    }
+
+    /**
+     * Use the provided |applicableRedactions| to check the receiving app's
+     * permissions and clear/set the corresponding bit in the returned bitmask. The bitmask
+     * returned will be used to ensure the necessary redactions are performed by NetworkCapabilities
+     * before being sent to the corresponding app.
+     */
+    private @NetworkCapabilities.RedactionType long retrieveRequiredRedactions(
+            @NetworkCapabilities.RedactionType long applicableRedactions,
+            @NonNull RedactionPermissionChecker redactionPermissionChecker,
+            boolean includeLocationSensitiveInfo) {
+        long redactions = applicableRedactions;
+        if (shouldRedact(redactions, REDACT_FOR_ACCESS_FINE_LOCATION)) {
+            if (includeLocationSensitiveInfo
+                    && redactionPermissionChecker.hasLocationPermission()) {
+                redactions &= ~REDACT_FOR_ACCESS_FINE_LOCATION;
+            }
+        }
+        if (shouldRedact(redactions, REDACT_FOR_LOCAL_MAC_ADDRESS)) {
+            if (redactionPermissionChecker.hasLocalMacAddressPermission()) {
+                redactions &= ~REDACT_FOR_LOCAL_MAC_ADDRESS;
+            }
+        }
+        if (shouldRedact(redactions, REDACT_FOR_NETWORK_SETTINGS)) {
+            if (redactionPermissionChecker.hasSettingsPermission()) {
+                redactions &= ~REDACT_FOR_NETWORK_SETTINGS;
+            }
+        }
+        return redactions;
+    }
+
+    @VisibleForTesting
+    @Nullable
+    NetworkCapabilities createWithLocationInfoSanitizedIfNecessaryWhenParceled(
+            @Nullable NetworkCapabilities nc, boolean includeLocationSensitiveInfo,
+            int callingPid, int callingUid, @NonNull String callingPkgName,
+            @Nullable String callingAttributionTag) {
+        if (nc == null) {
+            return null;
+        }
+        // Avoid doing location permission check if the transport info has no location sensitive
+        // data.
+        final RedactionPermissionChecker redactionPermissionChecker =
+                new RedactionPermissionChecker(callingPid, callingUid, callingPkgName,
+                        callingAttributionTag);
+        final long redactions = retrieveRequiredRedactions(
+                nc.getApplicableRedactions(), redactionPermissionChecker,
+                includeLocationSensitiveInfo);
+        final NetworkCapabilities newNc = new NetworkCapabilities(nc, redactions);
+        // Reset owner uid if not destined for the owner app.
+        if (callingUid != nc.getOwnerUid()) {
+            newNc.setOwnerUid(INVALID_UID);
+            return newNc;
+        }
+        // Allow VPNs to see ownership of their own VPN networks - not location sensitive.
+        if (nc.hasTransport(TRANSPORT_VPN)) {
+            // Owner UIDs already checked above. No need to re-check.
+            return newNc;
+        }
+        // If the calling does not want location sensitive data & target SDK >= S, then mask info.
+        // Else include the owner UID iff the calling has location permission to provide backwards
+        // compatibility for older apps.
+        if (!includeLocationSensitiveInfo
+                && isTargetSdkAtleast(
+                        Build.VERSION_CODES.S, callingUid, callingPkgName)) {
+            newNc.setOwnerUid(INVALID_UID);
+            return newNc;
+        }
+        // Reset owner uid if the app has no location permission.
+        if (!redactionPermissionChecker.hasLocationPermission()) {
+            newNc.setOwnerUid(INVALID_UID);
+        }
+        return newNc;
+    }
+
+    private LinkProperties linkPropertiesRestrictedForCallerPermissions(
+            LinkProperties lp, int callerPid, int callerUid) {
+        if (lp == null) return new LinkProperties();
+
+        // Only do a permission check if sanitization is needed, to avoid unnecessary binder calls.
+        final boolean needsSanitization =
+                (lp.getCaptivePortalApiUrl() != null || lp.getCaptivePortalData() != null);
+        if (!needsSanitization) {
+            return new LinkProperties(lp);
+        }
+
+        if (checkSettingsPermission(callerPid, callerUid)) {
+            return new LinkProperties(lp, true /* parcelSensitiveFields */);
+        }
+
+        final LinkProperties newLp = new LinkProperties(lp);
+        // Sensitive fields would not be parceled anyway, but sanitize for consistency before the
+        // object gets parceled.
+        newLp.setCaptivePortalApiUrl(null);
+        newLp.setCaptivePortalData(null);
+        return newLp;
+    }
+
+    private void restrictRequestUidsForCallerAndSetRequestorInfo(NetworkCapabilities nc,
+            int callerUid, String callerPackageName) {
+        if (!checkSettingsPermission()) {
+            // There is no need to track the effective UID of the request here. If the caller lacks
+            // the settings permission, the effective UID is the same as the calling ID.
+            nc.setSingleUid(callerUid);
+        }
+        nc.setRequestorUidAndPackageName(callerUid, callerPackageName);
+        nc.setAdministratorUids(new int[0]);
+
+        // Clear owner UID; this can never come from an app.
+        nc.setOwnerUid(INVALID_UID);
+    }
+
+    private void restrictBackgroundRequestForCaller(NetworkCapabilities nc) {
+        if (!mPermissionMonitor.hasUseBackgroundNetworksPermission(mDeps.getCallingUid())) {
+            nc.addCapability(NET_CAPABILITY_FOREGROUND);
+        }
+    }
+
+    @Override
+    public @RestrictBackgroundStatus int getRestrictBackgroundStatusByCaller() {
+        enforceAccessPermission();
+        final int callerUid = Binder.getCallingUid();
+        final long token = Binder.clearCallingIdentity();
+        try {
+            return mPolicyManager.getRestrictBackgroundStatus(callerUid);
+        } finally {
+            Binder.restoreCallingIdentity(token);
+        }
+    }
+
+    // TODO: Consider delete this function or turn it into a no-op method.
+    @Override
+    public NetworkState[] getAllNetworkState() {
+        // This contains IMSI details, so make sure the caller is privileged.
+        PermissionUtils.enforceNetworkStackPermission(mContext);
+
+        final ArrayList<NetworkState> result = new ArrayList<>();
+        for (NetworkStateSnapshot snapshot : getAllNetworkStateSnapshots()) {
+            // NetworkStateSnapshot doesn't contain NetworkInfo, so need to fetch it from the
+            // NetworkAgentInfo.
+            final NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(snapshot.getNetwork());
+            if (nai != null && nai.networkInfo.isConnected()) {
+                result.add(new NetworkState(new NetworkInfo(nai.networkInfo),
+                        snapshot.getLinkProperties(), snapshot.getNetworkCapabilities(),
+                        snapshot.getNetwork(), snapshot.getSubscriberId()));
+            }
+        }
+        return result.toArray(new NetworkState[result.size()]);
+    }
+
+    @Override
+    @NonNull
+    public List<NetworkStateSnapshot> getAllNetworkStateSnapshots() {
+        // This contains IMSI details, so make sure the caller is privileged.
+        PermissionUtils.enforceNetworkStackPermission(mContext);
+
+        final ArrayList<NetworkStateSnapshot> result = new ArrayList<>();
+        for (Network network : getAllNetworks()) {
+            final NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+            // TODO: Consider include SUSPENDED networks, which should be considered as
+            //  temporary shortage of connectivity of a connected network.
+            if (nai != null && nai.networkInfo.isConnected()) {
+                // TODO (b/73321673) : NetworkStateSnapshot contains a copy of the
+                // NetworkCapabilities, which may contain UIDs of apps to which the
+                // network applies. Should the UIDs be cleared so as not to leak or
+                // interfere ?
+                result.add(nai.getNetworkStateSnapshot());
+            }
+        }
+        return result;
+    }
+
+    @Override
+    public boolean isActiveNetworkMetered() {
+        enforceAccessPermission();
+
+        final NetworkCapabilities caps = getNetworkCapabilitiesInternal(getActiveNetwork());
+        if (caps != null) {
+            return !caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_METERED);
+        } else {
+            // Always return the most conservative value
+            return true;
+        }
+    }
+
+    /**
+     * Ensures that the system cannot call a particular method.
+     */
+    private boolean disallowedBecauseSystemCaller() {
+        // TODO: start throwing a SecurityException when GnssLocationProvider stops calling
+        // requestRouteToHost. In Q, GnssLocationProvider is changed to not call requestRouteToHost
+        // for devices launched with Q and above. However, existing devices upgrading to Q and
+        // above must continued to be supported for few more releases.
+        if (isSystem(mDeps.getCallingUid()) && SystemProperties.getInt(
+                "ro.product.first_api_level", 0) > Build.VERSION_CODES.P) {
+            log("This method exists only for app backwards compatibility"
+                    + " and must not be called by system services.");
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Ensure that a network route exists to deliver traffic to the specified
+     * host via the specified network interface.
+     * @param networkType the type of the network over which traffic to the
+     * specified host is to be routed
+     * @param hostAddress the IP address of the host to which the route is
+     * desired
+     * @return {@code true} on success, {@code false} on failure
+     */
+    @Override
+    public boolean requestRouteToHostAddress(int networkType, byte[] hostAddress,
+            String callingPackageName, String callingAttributionTag) {
+        if (disallowedBecauseSystemCaller()) {
+            return false;
+        }
+        enforceChangePermission(callingPackageName, callingAttributionTag);
+        if (mProtectedNetworks.contains(networkType)) {
+            enforceConnectivityRestrictedNetworksPermission();
+        }
+
+        InetAddress addr;
+        try {
+            addr = InetAddress.getByAddress(hostAddress);
+        } catch (UnknownHostException e) {
+            if (DBG) log("requestRouteToHostAddress got " + e.toString());
+            return false;
+        }
+
+        if (!ConnectivityManager.isNetworkTypeValid(networkType)) {
+            if (DBG) log("requestRouteToHostAddress on invalid network: " + networkType);
+            return false;
+        }
+
+        NetworkAgentInfo nai = mLegacyTypeTracker.getNetworkForType(networkType);
+        if (nai == null) {
+            if (mLegacyTypeTracker.isTypeSupported(networkType) == false) {
+                if (DBG) log("requestRouteToHostAddress on unsupported network: " + networkType);
+            } else {
+                if (DBG) log("requestRouteToHostAddress on down network: " + networkType);
+            }
+            return false;
+        }
+
+        DetailedState netState;
+        synchronized (nai) {
+            netState = nai.networkInfo.getDetailedState();
+        }
+
+        if (netState != DetailedState.CONNECTED && netState != DetailedState.CAPTIVE_PORTAL_CHECK) {
+            if (VDBG) {
+                log("requestRouteToHostAddress on down network "
+                        + "(" + networkType + ") - dropped"
+                        + " netState=" + netState);
+            }
+            return false;
+        }
+
+        final int uid = mDeps.getCallingUid();
+        final long token = Binder.clearCallingIdentity();
+        try {
+            LinkProperties lp;
+            int netId;
+            synchronized (nai) {
+                lp = nai.linkProperties;
+                netId = nai.network.getNetId();
+            }
+            boolean ok = addLegacyRouteToHost(lp, addr, netId, uid);
+            if (DBG) {
+                log("requestRouteToHostAddress " + addr + nai.toShortString() + " ok=" + ok);
+            }
+            return ok;
+        } finally {
+            Binder.restoreCallingIdentity(token);
+        }
+    }
+
+    private boolean addLegacyRouteToHost(LinkProperties lp, InetAddress addr, int netId, int uid) {
+        RouteInfo bestRoute = RouteInfo.selectBestRoute(lp.getAllRoutes(), addr);
+        if (bestRoute == null) {
+            bestRoute = RouteInfo.makeHostRoute(addr, lp.getInterfaceName());
+        } else {
+            String iface = bestRoute.getInterface();
+            if (bestRoute.getGateway().equals(addr)) {
+                // if there is no better route, add the implied hostroute for our gateway
+                bestRoute = RouteInfo.makeHostRoute(addr, iface);
+            } else {
+                // if we will connect to this through another route, add a direct route
+                // to it's gateway
+                bestRoute = RouteInfo.makeHostRoute(addr, bestRoute.getGateway(), iface);
+            }
+        }
+        if (DBG) log("Adding legacy route " + bestRoute +
+                " for UID/PID " + uid + "/" + Binder.getCallingPid());
+
+        final String dst = bestRoute.getDestinationLinkAddress().toString();
+        final String nextHop = bestRoute.hasGateway()
+                ? bestRoute.getGateway().getHostAddress() : "";
+        try {
+            mNetd.networkAddLegacyRoute(netId, bestRoute.getInterface(), dst, nextHop , uid);
+        } catch (RemoteException | ServiceSpecificException e) {
+            if (DBG) loge("Exception trying to add a route: " + e);
+            return false;
+        }
+        return true;
+    }
+
+    class DnsResolverUnsolicitedEventCallback extends
+            IDnsResolverUnsolicitedEventListener.Stub {
+        @Override
+        public void onPrivateDnsValidationEvent(final PrivateDnsValidationEventParcel event) {
+            try {
+                mHandler.sendMessage(mHandler.obtainMessage(
+                        EVENT_PRIVATE_DNS_VALIDATION_UPDATE,
+                        new PrivateDnsValidationUpdate(event.netId,
+                                InetAddresses.parseNumericAddress(event.ipAddress),
+                                event.hostname, event.validation)));
+            } catch (IllegalArgumentException e) {
+                loge("Error parsing ip address in validation event");
+            }
+        }
+
+        @Override
+        public void onDnsHealthEvent(final DnsHealthEventParcel event) {
+            NetworkAgentInfo nai = getNetworkAgentInfoForNetId(event.netId);
+            // Netd event only allow registrants from system. Each NetworkMonitor thread is under
+            // the caller thread of registerNetworkAgent. Thus, it's not allowed to register netd
+            // event callback for certain nai. e.g. cellular. Register here to pass to
+            // NetworkMonitor instead.
+            // TODO: Move the Dns Event to NetworkMonitor. NetdEventListenerService only allow one
+            // callback from each caller type. Need to re-factor NetdEventListenerService to allow
+            // multiple NetworkMonitor registrants.
+            if (nai != null && nai.satisfies(mDefaultRequest.mRequests.get(0))) {
+                nai.networkMonitor().notifyDnsResponse(event.healthResult);
+            }
+        }
+
+        @Override
+        public void onNat64PrefixEvent(final Nat64PrefixEventParcel event) {
+            mHandler.post(() -> handleNat64PrefixEvent(event.netId, event.prefixOperation,
+                    event.prefixAddress, event.prefixLength));
+        }
+
+        @Override
+        public int getInterfaceVersion() {
+            return this.VERSION;
+        }
+
+        @Override
+        public String getInterfaceHash() {
+            return this.HASH;
+        }
+    }
+
+    @VisibleForTesting
+    protected final DnsResolverUnsolicitedEventCallback mResolverUnsolEventCallback =
+            new DnsResolverUnsolicitedEventCallback();
+
+    private void registerDnsResolverUnsolicitedEventListener() {
+        try {
+            mDnsResolver.registerUnsolicitedEventListener(mResolverUnsolEventCallback);
+        } catch (Exception e) {
+            loge("Error registering DnsResolver unsolicited event callback: " + e);
+        }
+    }
+
+    private final NetworkPolicyCallback mPolicyCallback = new NetworkPolicyCallback() {
+        @Override
+        public void onUidBlockedReasonChanged(int uid, @BlockedReason int blockedReasons) {
+            mHandler.sendMessage(mHandler.obtainMessage(EVENT_UID_BLOCKED_REASON_CHANGED,
+                    uid, blockedReasons));
+        }
+    };
+
+    private void handleUidBlockedReasonChanged(int uid, @BlockedReason int blockedReasons) {
+        maybeNotifyNetworkBlockedForNewState(uid, blockedReasons);
+        setUidBlockedReasons(uid, blockedReasons);
+    }
+
+    private boolean checkAnyPermissionOf(String... permissions) {
+        for (String permission : permissions) {
+            if (mContext.checkCallingOrSelfPermission(permission) == PERMISSION_GRANTED) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private boolean checkAnyPermissionOf(int pid, int uid, String... permissions) {
+        for (String permission : permissions) {
+            if (mContext.checkPermission(permission, pid, uid) == PERMISSION_GRANTED) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private void enforceAnyPermissionOf(String... permissions) {
+        if (!checkAnyPermissionOf(permissions)) {
+            throw new SecurityException("Requires one of the following permissions: "
+                    + String.join(", ", permissions) + ".");
+        }
+    }
+
+    private void enforceInternetPermission() {
+        mContext.enforceCallingOrSelfPermission(
+                android.Manifest.permission.INTERNET,
+                "ConnectivityService");
+    }
+
+    private void enforceAccessPermission() {
+        mContext.enforceCallingOrSelfPermission(
+                android.Manifest.permission.ACCESS_NETWORK_STATE,
+                "ConnectivityService");
+    }
+
+    /**
+     * Performs a strict and comprehensive check of whether a calling package is allowed to
+     * change the state of network, as the condition differs for pre-M, M+, and
+     * privileged/preinstalled apps. The caller is expected to have either the
+     * CHANGE_NETWORK_STATE or the WRITE_SETTINGS permission declared. Either of these
+     * permissions allow changing network state; WRITE_SETTINGS is a runtime permission and
+     * can be revoked, but (except in M, excluding M MRs), CHANGE_NETWORK_STATE is a normal
+     * permission and cannot be revoked. See http://b/23597341
+     *
+     * Note: if the check succeeds because the application holds WRITE_SETTINGS, the operation
+     * of this app will be updated to the current time.
+     */
+    private void enforceChangePermission(String callingPkg, String callingAttributionTag) {
+        if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.CHANGE_NETWORK_STATE)
+                == PackageManager.PERMISSION_GRANTED) {
+            return;
+        }
+
+        if (callingPkg == null) {
+            throw new SecurityException("Calling package name is null.");
+        }
+
+        final AppOpsManager appOpsMgr = mContext.getSystemService(AppOpsManager.class);
+        final int uid = mDeps.getCallingUid();
+        final int mode = appOpsMgr.noteOpNoThrow(AppOpsManager.OPSTR_WRITE_SETTINGS, uid,
+                callingPkg, callingAttributionTag, null /* message */);
+
+        if (mode == AppOpsManager.MODE_ALLOWED) {
+            return;
+        }
+
+        if ((mode == AppOpsManager.MODE_DEFAULT) && (mContext.checkCallingOrSelfPermission(
+                android.Manifest.permission.WRITE_SETTINGS) == PackageManager.PERMISSION_GRANTED)) {
+            return;
+        }
+
+        throw new SecurityException(callingPkg + " was not granted either of these permissions:"
+                + android.Manifest.permission.CHANGE_NETWORK_STATE + ","
+                + android.Manifest.permission.WRITE_SETTINGS + ".");
+    }
+
+    private void enforceSettingsPermission() {
+        enforceAnyPermissionOf(
+                android.Manifest.permission.NETWORK_SETTINGS,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+    }
+
+    private void enforceNetworkFactoryPermission() {
+        enforceAnyPermissionOf(
+                android.Manifest.permission.NETWORK_FACTORY,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+    }
+
+    private void enforceNetworkFactoryOrSettingsPermission() {
+        enforceAnyPermissionOf(
+                android.Manifest.permission.NETWORK_SETTINGS,
+                android.Manifest.permission.NETWORK_FACTORY,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+    }
+
+    private void enforceNetworkFactoryOrTestNetworksPermission() {
+        enforceAnyPermissionOf(
+                android.Manifest.permission.MANAGE_TEST_NETWORKS,
+                android.Manifest.permission.NETWORK_FACTORY,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+    }
+
+    private boolean checkSettingsPermission() {
+        return checkAnyPermissionOf(
+                android.Manifest.permission.NETWORK_SETTINGS,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+    }
+
+    private boolean checkSettingsPermission(int pid, int uid) {
+        return PERMISSION_GRANTED == mContext.checkPermission(
+                android.Manifest.permission.NETWORK_SETTINGS, pid, uid)
+                || PERMISSION_GRANTED == mContext.checkPermission(
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK, pid, uid);
+    }
+
+    private void enforceNetworkStackOrSettingsPermission() {
+        enforceAnyPermissionOf(
+                android.Manifest.permission.NETWORK_SETTINGS,
+                android.Manifest.permission.NETWORK_STACK,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+    }
+
+    private void enforceNetworkStackSettingsOrSetup() {
+        enforceAnyPermissionOf(
+                android.Manifest.permission.NETWORK_SETTINGS,
+                android.Manifest.permission.NETWORK_SETUP_WIZARD,
+                android.Manifest.permission.NETWORK_STACK,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+    }
+
+    private void enforceAirplaneModePermission() {
+        enforceAnyPermissionOf(
+                android.Manifest.permission.NETWORK_AIRPLANE_MODE,
+                android.Manifest.permission.NETWORK_SETTINGS,
+                android.Manifest.permission.NETWORK_SETUP_WIZARD,
+                android.Manifest.permission.NETWORK_STACK,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+    }
+
+    private void enforceOemNetworkPreferencesPermission() {
+        mContext.enforceCallingOrSelfPermission(
+                android.Manifest.permission.CONTROL_OEM_PAID_NETWORK_PREFERENCE,
+                "ConnectivityService");
+    }
+
+    private boolean checkNetworkStackPermission() {
+        return checkAnyPermissionOf(
+                android.Manifest.permission.NETWORK_STACK,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+    }
+
+    private boolean checkNetworkStackPermission(int pid, int uid) {
+        return checkAnyPermissionOf(pid, uid,
+                android.Manifest.permission.NETWORK_STACK,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+    }
+
+    private boolean checkNetworkSignalStrengthWakeupPermission(int pid, int uid) {
+        return checkAnyPermissionOf(pid, uid,
+                android.Manifest.permission.NETWORK_SIGNAL_STRENGTH_WAKEUP,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK,
+                android.Manifest.permission.NETWORK_SETTINGS);
+    }
+
+    private void enforceConnectivityRestrictedNetworksPermission() {
+        try {
+            mContext.enforceCallingOrSelfPermission(
+                    android.Manifest.permission.CONNECTIVITY_USE_RESTRICTED_NETWORKS,
+                    "ConnectivityService");
+            return;
+        } catch (SecurityException e) { /* fallback to ConnectivityInternalPermission */ }
+        //  TODO: Remove this fallback check after all apps have declared
+        //   CONNECTIVITY_USE_RESTRICTED_NETWORKS.
+        mContext.enforceCallingOrSelfPermission(
+                android.Manifest.permission.CONNECTIVITY_INTERNAL,
+                "ConnectivityService");
+    }
+
+    private void enforceKeepalivePermission() {
+        mContext.enforceCallingOrSelfPermission(KeepaliveTracker.PERMISSION, "ConnectivityService");
+    }
+
+    private boolean checkLocalMacAddressPermission(int pid, int uid) {
+        return PERMISSION_GRANTED == mContext.checkPermission(
+                Manifest.permission.LOCAL_MAC_ADDRESS, pid, uid);
+    }
+
+    private void sendConnectedBroadcast(NetworkInfo info) {
+        sendGeneralBroadcast(info, CONNECTIVITY_ACTION);
+    }
+
+    private void sendInetConditionBroadcast(NetworkInfo info) {
+        sendGeneralBroadcast(info, ConnectivityManager.INET_CONDITION_ACTION);
+    }
+
+    private Intent makeGeneralIntent(NetworkInfo info, String bcastType) {
+        Intent intent = new Intent(bcastType);
+        intent.putExtra(ConnectivityManager.EXTRA_NETWORK_INFO, new NetworkInfo(info));
+        intent.putExtra(ConnectivityManager.EXTRA_NETWORK_TYPE, info.getType());
+        if (info.isFailover()) {
+            intent.putExtra(ConnectivityManager.EXTRA_IS_FAILOVER, true);
+            info.setFailover(false);
+        }
+        if (info.getReason() != null) {
+            intent.putExtra(ConnectivityManager.EXTRA_REASON, info.getReason());
+        }
+        if (info.getExtraInfo() != null) {
+            intent.putExtra(ConnectivityManager.EXTRA_EXTRA_INFO,
+                    info.getExtraInfo());
+        }
+        intent.putExtra(ConnectivityManager.EXTRA_INET_CONDITION, mDefaultInetConditionPublished);
+        return intent;
+    }
+
+    private void sendGeneralBroadcast(NetworkInfo info, String bcastType) {
+        sendStickyBroadcast(makeGeneralIntent(info, bcastType));
+    }
+
+    private void sendStickyBroadcast(Intent intent) {
+        synchronized (this) {
+            if (!mSystemReady
+                    && intent.getAction().equals(ConnectivityManager.CONNECTIVITY_ACTION)) {
+                mInitialBroadcast = new Intent(intent);
+            }
+            intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);
+            if (VDBG) {
+                log("sendStickyBroadcast: action=" + intent.getAction());
+            }
+
+            Bundle options = null;
+            final long ident = Binder.clearCallingIdentity();
+            if (ConnectivityManager.CONNECTIVITY_ACTION.equals(intent.getAction())) {
+                final NetworkInfo ni = intent.getParcelableExtra(
+                        ConnectivityManager.EXTRA_NETWORK_INFO);
+                final BroadcastOptions opts = BroadcastOptions.makeBasic();
+                opts.setMaxManifestReceiverApiLevel(Build.VERSION_CODES.M);
+                options = opts.toBundle();
+                intent.addFlags(Intent.FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS);
+            }
+            try {
+                mUserAllContext.sendStickyBroadcast(intent, options);
+            } finally {
+                Binder.restoreCallingIdentity(ident);
+            }
+        }
+    }
+
+    /**
+     * Called by SystemServer through ConnectivityManager when the system is ready.
+     */
+    @Override
+    public void systemReady() {
+        if (mDeps.getCallingUid() != Process.SYSTEM_UID) {
+            throw new SecurityException("Calling Uid is not system uid.");
+        }
+        systemReadyInternal();
+    }
+
+    /**
+     * Called when ConnectivityService can initialize remaining components.
+     */
+    @VisibleForTesting
+    public void systemReadyInternal() {
+        // Since mApps in PermissionMonitor needs to be populated first to ensure that
+        // listening network request which is sent by MultipathPolicyTracker won't be added
+        // NET_CAPABILITY_FOREGROUND capability. Thus, MultipathPolicyTracker.start() must
+        // be called after PermissionMonitor#startMonitoring().
+        // Calling PermissionMonitor#startMonitoring() in systemReadyInternal() and the
+        // MultipathPolicyTracker.start() is called in NetworkPolicyManagerService#systemReady()
+        // to ensure the tracking will be initialized correctly.
+        mPermissionMonitor.startMonitoring();
+        mProxyTracker.loadGlobalProxy();
+        registerDnsResolverUnsolicitedEventListener();
+
+        synchronized (this) {
+            mSystemReady = true;
+            if (mInitialBroadcast != null) {
+                mContext.sendStickyBroadcastAsUser(mInitialBroadcast, UserHandle.ALL);
+                mInitialBroadcast = null;
+            }
+        }
+
+        // Create network requests for always-on networks.
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_CONFIGURE_ALWAYS_ON_NETWORKS));
+    }
+
+    /**
+     * Start listening for default data network activity state changes.
+     */
+    @Override
+    public void registerNetworkActivityListener(@NonNull INetworkActivityListener l) {
+        mNetworkActivityTracker.registerNetworkActivityListener(l);
+    }
+
+    /**
+     * Stop listening for default data network activity state changes.
+     */
+    @Override
+    public void unregisterNetworkActivityListener(@NonNull INetworkActivityListener l) {
+        mNetworkActivityTracker.unregisterNetworkActivityListener(l);
+    }
+
+    /**
+     * Check whether the default network radio is currently active.
+     */
+    @Override
+    public boolean isDefaultNetworkActive() {
+        return mNetworkActivityTracker.isDefaultNetworkActive();
+    }
+
+    /**
+     * Reads the network specific MTU size from resources.
+     * and set it on it's iface.
+     */
+    private void updateMtu(LinkProperties newLp, LinkProperties oldLp) {
+        final String iface = newLp.getInterfaceName();
+        final int mtu = newLp.getMtu();
+        if (oldLp == null && mtu == 0) {
+            // Silently ignore unset MTU value.
+            return;
+        }
+        if (oldLp != null && newLp.isIdenticalMtu(oldLp)) {
+            if (VDBG) log("identical MTU - not setting");
+            return;
+        }
+        if (!LinkProperties.isValidMtu(mtu, newLp.hasGlobalIpv6Address())) {
+            if (mtu != 0) loge("Unexpected mtu value: " + mtu + ", " + iface);
+            return;
+        }
+
+        // Cannot set MTU without interface name
+        if (TextUtils.isEmpty(iface)) {
+            loge("Setting MTU size with null iface.");
+            return;
+        }
+
+        try {
+            if (VDBG || DDBG) log("Setting MTU size: " + iface + ", " + mtu);
+            mNetd.interfaceSetMtu(iface, mtu);
+        } catch (RemoteException | ServiceSpecificException e) {
+            loge("exception in interfaceSetMtu()" + e);
+        }
+    }
+
+    @VisibleForTesting
+    protected static final String DEFAULT_TCP_BUFFER_SIZES = "4096,87380,110208,4096,16384,110208";
+
+    private void updateTcpBufferSizes(String tcpBufferSizes) {
+        String[] values = null;
+        if (tcpBufferSizes != null) {
+            values = tcpBufferSizes.split(",");
+        }
+
+        if (values == null || values.length != 6) {
+            if (DBG) log("Invalid tcpBufferSizes string: " + tcpBufferSizes +", using defaults");
+            tcpBufferSizes = DEFAULT_TCP_BUFFER_SIZES;
+            values = tcpBufferSizes.split(",");
+        }
+
+        if (tcpBufferSizes.equals(mCurrentTcpBufferSizes)) return;
+
+        try {
+            if (VDBG || DDBG) log("Setting tx/rx TCP buffers to " + tcpBufferSizes);
+
+            String rmemValues = String.join(" ", values[0], values[1], values[2]);
+            String wmemValues = String.join(" ", values[3], values[4], values[5]);
+            mNetd.setTcpRWmemorySize(rmemValues, wmemValues);
+            mCurrentTcpBufferSizes = tcpBufferSizes;
+        } catch (RemoteException | ServiceSpecificException e) {
+            loge("Can't set TCP buffer sizes:" + e);
+        }
+    }
+
+    @Override
+    public int getRestoreDefaultNetworkDelay(int networkType) {
+        String restoreDefaultNetworkDelayStr = mSystemProperties.get(
+                NETWORK_RESTORE_DELAY_PROP_NAME);
+        if(restoreDefaultNetworkDelayStr != null &&
+                restoreDefaultNetworkDelayStr.length() != 0) {
+            try {
+                return Integer.parseInt(restoreDefaultNetworkDelayStr);
+            } catch (NumberFormatException e) {
+            }
+        }
+        // if the system property isn't set, use the value for the apn type
+        int ret = RESTORE_DEFAULT_NETWORK_DELAY;
+
+        if (mLegacyTypeTracker.isTypeSupported(networkType)) {
+            ret = mLegacyTypeTracker.getRestoreTimerForType(networkType);
+        }
+        return ret;
+    }
+
+    private void dumpNetworkDiagnostics(IndentingPrintWriter pw) {
+        final List<NetworkDiagnostics> netDiags = new ArrayList<NetworkDiagnostics>();
+        final long DIAG_TIME_MS = 5000;
+        for (NetworkAgentInfo nai : networksSortedById()) {
+            PrivateDnsConfig privateDnsCfg = mDnsManager.getPrivateDnsConfig(nai.network);
+            // Start gathering diagnostic information.
+            netDiags.add(new NetworkDiagnostics(
+                    nai.network,
+                    new LinkProperties(nai.linkProperties),  // Must be a copy.
+                    privateDnsCfg,
+                    DIAG_TIME_MS));
+        }
+
+        for (NetworkDiagnostics netDiag : netDiags) {
+            pw.println();
+            netDiag.waitForMeasurements();
+            netDiag.dump(pw);
+        }
+    }
+
+    @Override
+    protected void dump(@NonNull FileDescriptor fd, @NonNull PrintWriter writer,
+            @Nullable String[] args) {
+        if (!checkDumpPermission(mContext, TAG, writer)) return;
+
+        mPriorityDumper.dump(fd, writer, args);
+    }
+
+    private boolean checkDumpPermission(Context context, String tag, PrintWriter pw) {
+        if (context.checkCallingOrSelfPermission(android.Manifest.permission.DUMP)
+                != PackageManager.PERMISSION_GRANTED) {
+            pw.println("Permission Denial: can't dump " + tag + " from from pid="
+                    + Binder.getCallingPid() + ", uid=" + mDeps.getCallingUid()
+                    + " due to missing android.permission.DUMP permission");
+            return false;
+        } else {
+            return true;
+        }
+    }
+
+    private void doDump(FileDescriptor fd, PrintWriter writer, String[] args) {
+        final IndentingPrintWriter pw = new IndentingPrintWriter(writer, "  ");
+
+        if (CollectionUtils.contains(args, DIAG_ARG)) {
+            dumpNetworkDiagnostics(pw);
+            return;
+        } else if (CollectionUtils.contains(args, NETWORK_ARG)) {
+            dumpNetworks(pw);
+            return;
+        } else if (CollectionUtils.contains(args, REQUEST_ARG)) {
+            dumpNetworkRequests(pw);
+            return;
+        }
+
+        pw.print("NetworkProviders for:");
+        for (NetworkProviderInfo npi : mNetworkProviderInfos.values()) {
+            pw.print(" " + npi.name);
+        }
+        pw.println();
+        pw.println();
+
+        final NetworkAgentInfo defaultNai = getDefaultNetwork();
+        pw.print("Active default network: ");
+        if (defaultNai == null) {
+            pw.println("none");
+        } else {
+            pw.println(defaultNai.network.getNetId());
+        }
+        pw.println();
+
+        pw.print("Current per-app default networks: ");
+        pw.increaseIndent();
+        dumpPerAppNetworkPreferences(pw);
+        pw.decreaseIndent();
+        pw.println();
+
+        pw.println("Current Networks:");
+        pw.increaseIndent();
+        dumpNetworks(pw);
+        pw.decreaseIndent();
+        pw.println();
+
+        pw.println("Status for known UIDs:");
+        pw.increaseIndent();
+        final int size = mUidBlockedReasons.size();
+        for (int i = 0; i < size; i++) {
+            // Don't crash if the array is modified while dumping in bugreports.
+            try {
+                final int uid = mUidBlockedReasons.keyAt(i);
+                final int blockedReasons = mUidBlockedReasons.valueAt(i);
+                pw.println("UID=" + uid + " blockedReasons="
+                        + Integer.toHexString(blockedReasons));
+            } catch (ArrayIndexOutOfBoundsException e) {
+                pw.println("  ArrayIndexOutOfBoundsException");
+            } catch (ConcurrentModificationException e) {
+                pw.println("  ConcurrentModificationException");
+            }
+        }
+        pw.println();
+        pw.decreaseIndent();
+
+        pw.println("Network Requests:");
+        pw.increaseIndent();
+        dumpNetworkRequests(pw);
+        pw.decreaseIndent();
+        pw.println();
+
+        mLegacyTypeTracker.dump(pw);
+
+        pw.println();
+        mKeepaliveTracker.dump(pw);
+
+        pw.println();
+        dumpAvoidBadWifiSettings(pw);
+
+        pw.println();
+
+        if (!CollectionUtils.contains(args, SHORT_ARG)) {
+            pw.println();
+            pw.println("mNetworkRequestInfoLogs (most recent first):");
+            pw.increaseIndent();
+            mNetworkRequestInfoLogs.reverseDump(pw);
+            pw.decreaseIndent();
+
+            pw.println();
+            pw.println("mNetworkInfoBlockingLogs (most recent first):");
+            pw.increaseIndent();
+            mNetworkInfoBlockingLogs.reverseDump(pw);
+            pw.decreaseIndent();
+
+            pw.println();
+            pw.println("NetTransition WakeLock activity (most recent first):");
+            pw.increaseIndent();
+            pw.println("total acquisitions: " + mTotalWakelockAcquisitions);
+            pw.println("total releases: " + mTotalWakelockReleases);
+            pw.println("cumulative duration: " + (mTotalWakelockDurationMs / 1000) + "s");
+            pw.println("longest duration: " + (mMaxWakelockDurationMs / 1000) + "s");
+            if (mTotalWakelockAcquisitions > mTotalWakelockReleases) {
+                long duration = SystemClock.elapsedRealtime() - mLastWakeLockAcquireTimestamp;
+                pw.println("currently holding WakeLock for: " + (duration / 1000) + "s");
+            }
+            mWakelockLogs.reverseDump(pw);
+
+            pw.println();
+            pw.println("bandwidth update requests (by uid):");
+            pw.increaseIndent();
+            synchronized (mBandwidthRequests) {
+                for (int i = 0; i < mBandwidthRequests.size(); i++) {
+                    pw.println("[" + mBandwidthRequests.keyAt(i)
+                            + "]: " + mBandwidthRequests.valueAt(i));
+                }
+            }
+            pw.decreaseIndent();
+            pw.decreaseIndent();
+
+            pw.println();
+            pw.println("mOemNetworkPreferencesLogs (most recent first):");
+            pw.increaseIndent();
+            mOemNetworkPreferencesLogs.reverseDump(pw);
+            pw.decreaseIndent();
+        }
+
+        pw.println();
+
+        pw.println();
+        pw.println("Permission Monitor:");
+        pw.increaseIndent();
+        mPermissionMonitor.dump(pw);
+        pw.decreaseIndent();
+
+        pw.println();
+        pw.println("Legacy network activity:");
+        pw.increaseIndent();
+        mNetworkActivityTracker.dump(pw);
+        pw.decreaseIndent();
+    }
+
+    private void dumpNetworks(IndentingPrintWriter pw) {
+        for (NetworkAgentInfo nai : networksSortedById()) {
+            pw.println(nai.toString());
+            pw.increaseIndent();
+            pw.println(String.format(
+                    "Requests: REQUEST:%d LISTEN:%d BACKGROUND_REQUEST:%d total:%d",
+                    nai.numForegroundNetworkRequests(),
+                    nai.numNetworkRequests() - nai.numRequestNetworkRequests(),
+                    nai.numBackgroundNetworkRequests(),
+                    nai.numNetworkRequests()));
+            pw.increaseIndent();
+            for (int i = 0; i < nai.numNetworkRequests(); i++) {
+                pw.println(nai.requestAt(i).toString());
+            }
+            pw.decreaseIndent();
+            pw.println("Inactivity Timers:");
+            pw.increaseIndent();
+            nai.dumpInactivityTimers(pw);
+            pw.decreaseIndent();
+            pw.decreaseIndent();
+        }
+    }
+
+    private void dumpPerAppNetworkPreferences(IndentingPrintWriter pw) {
+        pw.println("Per-App Network Preference:");
+        pw.increaseIndent();
+        if (0 == mOemNetworkPreferences.getNetworkPreferences().size()) {
+            pw.println("none");
+        } else {
+            pw.println(mOemNetworkPreferences.toString());
+        }
+        pw.decreaseIndent();
+
+        for (final NetworkRequestInfo defaultRequest : mDefaultNetworkRequests) {
+            if (mDefaultRequest == defaultRequest) {
+                continue;
+            }
+
+            final boolean isActive = null != defaultRequest.getSatisfier();
+            pw.println("Is per-app network active:");
+            pw.increaseIndent();
+            pw.println(isActive);
+            if (isActive) {
+                pw.println("Active network: " + defaultRequest.getSatisfier().network.netId);
+            }
+            pw.println("Tracked UIDs:");
+            pw.increaseIndent();
+            if (0 == defaultRequest.mRequests.size()) {
+                pw.println("none, this should never occur.");
+            } else {
+                pw.println(defaultRequest.mRequests.get(0).networkCapabilities.getUidRanges());
+            }
+            pw.decreaseIndent();
+            pw.decreaseIndent();
+        }
+    }
+
+    private void dumpNetworkRequests(IndentingPrintWriter pw) {
+        for (NetworkRequestInfo nri : requestsSortedById()) {
+            pw.println(nri.toString());
+        }
+    }
+
+    /**
+     * Return an array of all current NetworkAgentInfos sorted by network id.
+     */
+    private NetworkAgentInfo[] networksSortedById() {
+        NetworkAgentInfo[] networks = new NetworkAgentInfo[0];
+        networks = mNetworkAgentInfos.toArray(networks);
+        Arrays.sort(networks, Comparator.comparingInt(nai -> nai.network.getNetId()));
+        return networks;
+    }
+
+    /**
+     * Return an array of all current NetworkRequest sorted by request id.
+     */
+    @VisibleForTesting
+    NetworkRequestInfo[] requestsSortedById() {
+        NetworkRequestInfo[] requests = new NetworkRequestInfo[0];
+        requests = getNrisFromGlobalRequests().toArray(requests);
+        // Sort the array based off the NRI containing the min requestId in its requests.
+        Arrays.sort(requests,
+                Comparator.comparingInt(nri -> Collections.min(nri.mRequests,
+                        Comparator.comparingInt(req -> req.requestId)).requestId
+                )
+        );
+        return requests;
+    }
+
+    private boolean isLiveNetworkAgent(NetworkAgentInfo nai, int what) {
+        final NetworkAgentInfo officialNai = getNetworkAgentInfoForNetwork(nai.network);
+        if (officialNai != null && officialNai.equals(nai)) return true;
+        if (officialNai != null || VDBG) {
+            loge(eventName(what) + " - isLiveNetworkAgent found mismatched netId: " + officialNai +
+                " - " + nai);
+        }
+        return false;
+    }
+
+    // must be stateless - things change under us.
+    private class NetworkStateTrackerHandler extends Handler {
+        public NetworkStateTrackerHandler(Looper looper) {
+            super(looper);
+        }
+
+        private void maybeHandleNetworkAgentMessage(Message msg) {
+            final Pair<NetworkAgentInfo, Object> arg = (Pair<NetworkAgentInfo, Object>) msg.obj;
+            final NetworkAgentInfo nai = arg.first;
+            if (!mNetworkAgentInfos.contains(nai)) {
+                if (VDBG) {
+                    log(String.format("%s from unknown NetworkAgent", eventName(msg.what)));
+                }
+                return;
+            }
+
+            switch (msg.what) {
+                case NetworkAgent.EVENT_NETWORK_CAPABILITIES_CHANGED: {
+                    NetworkCapabilities networkCapabilities = (NetworkCapabilities) arg.second;
+                    if (networkCapabilities.hasConnectivityManagedCapability()) {
+                        Log.wtf(TAG, "BUG: " + nai + " has CS-managed capability.");
+                    }
+                    if (networkCapabilities.hasTransport(TRANSPORT_TEST)) {
+                        // Make sure the original object is not mutated. NetworkAgent normally
+                        // makes a copy of the capabilities when sending the message through
+                        // the Messenger, but if this ever changes, not making a defensive copy
+                        // here will give attack vectors to clients using this code path.
+                        networkCapabilities = new NetworkCapabilities(networkCapabilities);
+                        networkCapabilities.restrictCapabilitesForTestNetwork(nai.creatorUid);
+                    }
+                    processCapabilitiesFromAgent(nai, networkCapabilities);
+                    updateCapabilities(nai.getCurrentScore(), nai, networkCapabilities);
+                    break;
+                }
+                case NetworkAgent.EVENT_NETWORK_PROPERTIES_CHANGED: {
+                    LinkProperties newLp = (LinkProperties) arg.second;
+                    processLinkPropertiesFromAgent(nai, newLp);
+                    handleUpdateLinkProperties(nai, newLp);
+                    break;
+                }
+                case NetworkAgent.EVENT_NETWORK_INFO_CHANGED: {
+                    NetworkInfo info = (NetworkInfo) arg.second;
+                    updateNetworkInfo(nai, info);
+                    break;
+                }
+                case NetworkAgent.EVENT_NETWORK_SCORE_CHANGED: {
+                    updateNetworkScore(nai, (NetworkScore) arg.second);
+                    break;
+                }
+                case NetworkAgent.EVENT_SET_EXPLICITLY_SELECTED: {
+                    if (nai.everConnected) {
+                        loge("ERROR: cannot call explicitlySelected on already-connected network");
+                        // Note that if the NAI had been connected, this would affect the
+                        // score, and therefore would require re-mixing the score and performing
+                        // a rematch.
+                    }
+                    nai.networkAgentConfig.explicitlySelected = toBool(msg.arg1);
+                    nai.networkAgentConfig.acceptUnvalidated = toBool(msg.arg1) && toBool(msg.arg2);
+                    // Mark the network as temporarily accepting partial connectivity so that it
+                    // will be validated (and possibly become default) even if it only provides
+                    // partial internet access. Note that if user connects to partial connectivity
+                    // and choose "don't ask again", then wifi disconnected by some reasons(maybe
+                    // out of wifi coverage) and if the same wifi is available again, the device
+                    // will auto connect to this wifi even though the wifi has "no internet".
+                    // TODO: Evaluate using a separate setting in IpMemoryStore.
+                    nai.networkAgentConfig.acceptPartialConnectivity = toBool(msg.arg2);
+                    break;
+                }
+                case NetworkAgent.EVENT_SOCKET_KEEPALIVE: {
+                    mKeepaliveTracker.handleEventSocketKeepalive(nai, msg.arg1, msg.arg2);
+                    break;
+                }
+                case NetworkAgent.EVENT_UNDERLYING_NETWORKS_CHANGED: {
+                    // TODO: prevent loops, e.g., if a network declares itself as underlying.
+                    if (!nai.supportsUnderlyingNetworks()) {
+                        Log.wtf(TAG, "Non-virtual networks cannot have underlying networks");
+                        break;
+                    }
+
+                    final List<Network> underlying = (List<Network>) arg.second;
+
+                    if (isLegacyLockdownNai(nai)
+                            && (underlying == null || underlying.size() != 1)) {
+                        Log.wtf(TAG, "Legacy lockdown VPN " + nai.toShortString()
+                                + " must have exactly one underlying network: " + underlying);
+                    }
+
+                    final Network[] oldUnderlying = nai.declaredUnderlyingNetworks;
+                    nai.declaredUnderlyingNetworks = (underlying != null)
+                            ? underlying.toArray(new Network[0]) : null;
+
+                    if (!Arrays.equals(oldUnderlying, nai.declaredUnderlyingNetworks)) {
+                        if (DBG) {
+                            log(nai.toShortString() + " changed underlying networks to "
+                                    + Arrays.toString(nai.declaredUnderlyingNetworks));
+                        }
+                        updateCapabilitiesForNetwork(nai);
+                        notifyIfacesChangedForNetworkStats();
+                    }
+                    break;
+                }
+                case NetworkAgent.EVENT_TEARDOWN_DELAY_CHANGED: {
+                    if (msg.arg1 >= 0 && msg.arg1 <= NetworkAgent.MAX_TEARDOWN_DELAY_MS) {
+                        nai.teardownDelayMs = msg.arg1;
+                    } else {
+                        logwtf(nai.toShortString() + " set invalid teardown delay " + msg.arg1);
+                    }
+                    break;
+                }
+                case NetworkAgent.EVENT_LINGER_DURATION_CHANGED: {
+                    nai.setLingerDuration((int) arg.second);
+                    break;
+                }
+            }
+        }
+
+        private boolean maybeHandleNetworkMonitorMessage(Message msg) {
+            switch (msg.what) {
+                default:
+                    return false;
+                case EVENT_PROBE_STATUS_CHANGED: {
+                    final Integer netId = (Integer) msg.obj;
+                    final NetworkAgentInfo nai = getNetworkAgentInfoForNetId(netId);
+                    if (nai == null) {
+                        break;
+                    }
+                    final boolean probePrivateDnsCompleted =
+                            ((msg.arg1 & NETWORK_VALIDATION_PROBE_PRIVDNS) != 0);
+                    final boolean privateDnsBroken =
+                            ((msg.arg2 & NETWORK_VALIDATION_PROBE_PRIVDNS) == 0);
+                    if (probePrivateDnsCompleted) {
+                        if (nai.networkCapabilities.isPrivateDnsBroken() != privateDnsBroken) {
+                            nai.networkCapabilities.setPrivateDnsBroken(privateDnsBroken);
+                            updateCapabilitiesForNetwork(nai);
+                        }
+                        // Only show the notification when the private DNS is broken and the
+                        // PRIVATE_DNS_BROKEN notification hasn't shown since last valid.
+                        if (privateDnsBroken && !nai.networkAgentConfig.hasShownBroken) {
+                            showNetworkNotification(nai, NotificationType.PRIVATE_DNS_BROKEN);
+                        }
+                        nai.networkAgentConfig.hasShownBroken = privateDnsBroken;
+                    } else if (nai.networkCapabilities.isPrivateDnsBroken()) {
+                        // If probePrivateDnsCompleted is false but nai.networkCapabilities says
+                        // private DNS is broken, it means this network is being reevaluated.
+                        // Either probing private DNS is not necessary any more or it hasn't been
+                        // done yet. In either case, the networkCapabilities should be updated to
+                        // reflect the new status.
+                        nai.networkCapabilities.setPrivateDnsBroken(false);
+                        updateCapabilitiesForNetwork(nai);
+                        nai.networkAgentConfig.hasShownBroken = false;
+                    }
+                    break;
+                }
+                case EVENT_NETWORK_TESTED: {
+                    final NetworkTestedResults results = (NetworkTestedResults) msg.obj;
+
+                    final NetworkAgentInfo nai = getNetworkAgentInfoForNetId(results.mNetId);
+                    if (nai == null) break;
+
+                    handleNetworkTested(nai, results.mTestResult,
+                            (results.mRedirectUrl == null) ? "" : results.mRedirectUrl);
+                    break;
+                }
+                case EVENT_PROVISIONING_NOTIFICATION: {
+                    final int netId = msg.arg2;
+                    final boolean visible = toBool(msg.arg1);
+                    final NetworkAgentInfo nai = getNetworkAgentInfoForNetId(netId);
+                    // If captive portal status has changed, update capabilities or disconnect.
+                    if (nai != null && (visible != nai.lastCaptivePortalDetected)) {
+                        nai.lastCaptivePortalDetected = visible;
+                        nai.everCaptivePortalDetected |= visible;
+                        if (nai.lastCaptivePortalDetected &&
+                                ConnectivitySettingsManager.CAPTIVE_PORTAL_MODE_AVOID
+                                        == getCaptivePortalMode()) {
+                            if (DBG) log("Avoiding captive portal network: " + nai.toShortString());
+                            nai.onPreventAutomaticReconnect();
+                            teardownUnneededNetwork(nai);
+                            break;
+                        }
+                        updateCapabilitiesForNetwork(nai);
+                    }
+                    if (!visible) {
+                        // Only clear SIGN_IN and NETWORK_SWITCH notifications here, or else other
+                        // notifications belong to the same network may be cleared unexpectedly.
+                        mNotifier.clearNotification(netId, NotificationType.SIGN_IN);
+                        mNotifier.clearNotification(netId, NotificationType.NETWORK_SWITCH);
+                    } else {
+                        if (nai == null) {
+                            loge("EVENT_PROVISIONING_NOTIFICATION from unknown NetworkMonitor");
+                            break;
+                        }
+                        if (!nai.networkAgentConfig.provisioningNotificationDisabled) {
+                            mNotifier.showNotification(netId, NotificationType.SIGN_IN, nai, null,
+                                    (PendingIntent) msg.obj,
+                                    nai.networkAgentConfig.explicitlySelected);
+                        }
+                    }
+                    break;
+                }
+                case EVENT_PRIVATE_DNS_CONFIG_RESOLVED: {
+                    final NetworkAgentInfo nai = getNetworkAgentInfoForNetId(msg.arg2);
+                    if (nai == null) break;
+
+                    updatePrivateDns(nai, (PrivateDnsConfig) msg.obj);
+                    break;
+                }
+                case EVENT_CAPPORT_DATA_CHANGED: {
+                    final NetworkAgentInfo nai = getNetworkAgentInfoForNetId(msg.arg2);
+                    if (nai == null) break;
+                    handleCapportApiDataUpdate(nai, (CaptivePortalData) msg.obj);
+                    break;
+                }
+            }
+            return true;
+        }
+
+        private void handleNetworkTested(
+                @NonNull NetworkAgentInfo nai, int testResult, @NonNull String redirectUrl) {
+            final boolean wasPartial = nai.partialConnectivity;
+            nai.partialConnectivity = ((testResult & NETWORK_VALIDATION_RESULT_PARTIAL) != 0);
+            final boolean partialConnectivityChanged =
+                    (wasPartial != nai.partialConnectivity);
+
+            final boolean valid = ((testResult & NETWORK_VALIDATION_RESULT_VALID) != 0);
+            final boolean wasValidated = nai.lastValidated;
+            final boolean wasDefault = isDefaultNetwork(nai);
+
+            if (DBG) {
+                final String logMsg = !TextUtils.isEmpty(redirectUrl)
+                        ? " with redirect to " + redirectUrl
+                        : "";
+                log(nai.toShortString() + " validation " + (valid ? "passed" : "failed") + logMsg);
+            }
+            if (valid != nai.lastValidated) {
+                final int oldScore = nai.getCurrentScore();
+                nai.lastValidated = valid;
+                nai.everValidated |= valid;
+                updateCapabilities(oldScore, nai, nai.networkCapabilities);
+                if (valid) {
+                    handleFreshlyValidatedNetwork(nai);
+                    // Clear NO_INTERNET, PRIVATE_DNS_BROKEN, PARTIAL_CONNECTIVITY and
+                    // LOST_INTERNET notifications if network becomes valid.
+                    mNotifier.clearNotification(nai.network.getNetId(),
+                            NotificationType.NO_INTERNET);
+                    mNotifier.clearNotification(nai.network.getNetId(),
+                            NotificationType.LOST_INTERNET);
+                    mNotifier.clearNotification(nai.network.getNetId(),
+                            NotificationType.PARTIAL_CONNECTIVITY);
+                    mNotifier.clearNotification(nai.network.getNetId(),
+                            NotificationType.PRIVATE_DNS_BROKEN);
+                    // If network becomes valid, the hasShownBroken should be reset for
+                    // that network so that the notification will be fired when the private
+                    // DNS is broken again.
+                    nai.networkAgentConfig.hasShownBroken = false;
+                }
+            } else if (partialConnectivityChanged) {
+                updateCapabilitiesForNetwork(nai);
+            }
+            updateInetCondition(nai);
+            // Let the NetworkAgent know the state of its network
+            // TODO: Evaluate to update partial connectivity to status to NetworkAgent.
+            nai.onValidationStatusChanged(
+                    valid ? NetworkAgent.VALID_NETWORK : NetworkAgent.INVALID_NETWORK,
+                    redirectUrl);
+
+            // If NetworkMonitor detects partial connectivity before
+            // EVENT_PROMPT_UNVALIDATED arrives, show the partial connectivity notification
+            // immediately. Re-notify partial connectivity silently if no internet
+            // notification already there.
+            if (!wasPartial && nai.partialConnectivity) {
+                // Remove delayed message if there is a pending message.
+                mHandler.removeMessages(EVENT_PROMPT_UNVALIDATED, nai.network);
+                handlePromptUnvalidated(nai.network);
+            }
+
+            if (wasValidated && !nai.lastValidated) {
+                handleNetworkUnvalidated(nai);
+            }
+        }
+
+        private int getCaptivePortalMode() {
+            return Settings.Global.getInt(mContext.getContentResolver(),
+                    ConnectivitySettingsManager.CAPTIVE_PORTAL_MODE,
+                    ConnectivitySettingsManager.CAPTIVE_PORTAL_MODE_PROMPT);
+        }
+
+        private boolean maybeHandleNetworkAgentInfoMessage(Message msg) {
+            switch (msg.what) {
+                default:
+                    return false;
+                case NetworkAgentInfo.EVENT_NETWORK_LINGER_COMPLETE: {
+                    NetworkAgentInfo nai = (NetworkAgentInfo) msg.obj;
+                    if (nai != null && isLiveNetworkAgent(nai, msg.what)) {
+                        handleLingerComplete(nai);
+                    }
+                    break;
+                }
+                case NetworkAgentInfo.EVENT_AGENT_REGISTERED: {
+                    handleNetworkAgentRegistered(msg);
+                    break;
+                }
+                case NetworkAgentInfo.EVENT_AGENT_DISCONNECTED: {
+                    handleNetworkAgentDisconnected(msg);
+                    break;
+                }
+            }
+            return true;
+        }
+
+        @Override
+        public void handleMessage(Message msg) {
+            if (!maybeHandleNetworkMonitorMessage(msg)
+                    && !maybeHandleNetworkAgentInfoMessage(msg)) {
+                maybeHandleNetworkAgentMessage(msg);
+            }
+        }
+    }
+
+    private class NetworkMonitorCallbacks extends INetworkMonitorCallbacks.Stub {
+        private final int mNetId;
+        private final AutodestructReference<NetworkAgentInfo> mNai;
+
+        private NetworkMonitorCallbacks(NetworkAgentInfo nai) {
+            mNetId = nai.network.getNetId();
+            mNai = new AutodestructReference<>(nai);
+        }
+
+        @Override
+        public void onNetworkMonitorCreated(INetworkMonitor networkMonitor) {
+            mHandler.sendMessage(mHandler.obtainMessage(EVENT_REGISTER_NETWORK_AGENT,
+                    new Pair<>(mNai.getAndDestroy(), networkMonitor)));
+        }
+
+        @Override
+        public void notifyNetworkTested(int testResult, @Nullable String redirectUrl) {
+            // Legacy version of notifyNetworkTestedWithExtras.
+            // Would only be called if the system has a NetworkStack module older than the
+            // framework, which does not happen in practice.
+            Log.wtf(TAG, "Deprecated notifyNetworkTested called: no action taken");
+        }
+
+        @Override
+        public void notifyNetworkTestedWithExtras(NetworkTestResultParcelable p) {
+            // Notify mTrackerHandler and mConnectivityDiagnosticsHandler of the event. Both use
+            // the same looper so messages will be processed in sequence.
+            final Message msg = mTrackerHandler.obtainMessage(
+                    EVENT_NETWORK_TESTED,
+                    new NetworkTestedResults(
+                            mNetId, p.result, p.timestampMillis, p.redirectUrl));
+            mTrackerHandler.sendMessage(msg);
+
+            // Invoke ConnectivityReport generation for this Network test event.
+            final NetworkAgentInfo nai = getNetworkAgentInfoForNetId(mNetId);
+            if (nai == null) return;
+
+            final PersistableBundle extras = new PersistableBundle();
+            extras.putInt(KEY_NETWORK_VALIDATION_RESULT, p.result);
+            extras.putInt(KEY_NETWORK_PROBES_SUCCEEDED_BITMASK, p.probesSucceeded);
+            extras.putInt(KEY_NETWORK_PROBES_ATTEMPTED_BITMASK, p.probesAttempted);
+
+            ConnectivityReportEvent reportEvent =
+                    new ConnectivityReportEvent(p.timestampMillis, nai, extras);
+            final Message m = mConnectivityDiagnosticsHandler.obtainMessage(
+                    ConnectivityDiagnosticsHandler.EVENT_NETWORK_TESTED, reportEvent);
+            mConnectivityDiagnosticsHandler.sendMessage(m);
+        }
+
+        @Override
+        public void notifyPrivateDnsConfigResolved(PrivateDnsConfigParcel config) {
+            mTrackerHandler.sendMessage(mTrackerHandler.obtainMessage(
+                    EVENT_PRIVATE_DNS_CONFIG_RESOLVED,
+                    0, mNetId, PrivateDnsConfig.fromParcel(config)));
+        }
+
+        @Override
+        public void notifyProbeStatusChanged(int probesCompleted, int probesSucceeded) {
+            mTrackerHandler.sendMessage(mTrackerHandler.obtainMessage(
+                    EVENT_PROBE_STATUS_CHANGED,
+                    probesCompleted, probesSucceeded, new Integer(mNetId)));
+        }
+
+        @Override
+        public void notifyCaptivePortalDataChanged(CaptivePortalData data) {
+            mTrackerHandler.sendMessage(mTrackerHandler.obtainMessage(
+                    EVENT_CAPPORT_DATA_CHANGED,
+                    0, mNetId, data));
+        }
+
+        @Override
+        public void showProvisioningNotification(String action, String packageName) {
+            final Intent intent = new Intent(action);
+            intent.setPackage(packageName);
+
+            final PendingIntent pendingIntent;
+            // Only the system server can register notifications with package "android"
+            final long token = Binder.clearCallingIdentity();
+            try {
+                pendingIntent = PendingIntent.getBroadcast(
+                        mContext,
+                        0 /* requestCode */,
+                        intent,
+                        PendingIntent.FLAG_IMMUTABLE);
+            } finally {
+                Binder.restoreCallingIdentity(token);
+            }
+            mTrackerHandler.sendMessage(mTrackerHandler.obtainMessage(
+                    EVENT_PROVISIONING_NOTIFICATION, PROVISIONING_NOTIFICATION_SHOW,
+                    mNetId, pendingIntent));
+        }
+
+        @Override
+        public void hideProvisioningNotification() {
+            mTrackerHandler.sendMessage(mTrackerHandler.obtainMessage(
+                    EVENT_PROVISIONING_NOTIFICATION, PROVISIONING_NOTIFICATION_HIDE, mNetId));
+        }
+
+        @Override
+        public void notifyDataStallSuspected(DataStallReportParcelable p) {
+            ConnectivityService.this.notifyDataStallSuspected(p, mNetId);
+        }
+
+        @Override
+        public int getInterfaceVersion() {
+            return this.VERSION;
+        }
+
+        @Override
+        public String getInterfaceHash() {
+            return this.HASH;
+        }
+    }
+
+    private void notifyDataStallSuspected(DataStallReportParcelable p, int netId) {
+        log("Data stall detected with methods: " + p.detectionMethod);
+
+        final PersistableBundle extras = new PersistableBundle();
+        int detectionMethod = 0;
+        if (hasDataStallDetectionMethod(p, DETECTION_METHOD_DNS_EVENTS)) {
+            extras.putInt(KEY_DNS_CONSECUTIVE_TIMEOUTS, p.dnsConsecutiveTimeouts);
+            detectionMethod |= DETECTION_METHOD_DNS_EVENTS;
+        }
+        if (hasDataStallDetectionMethod(p, DETECTION_METHOD_TCP_METRICS)) {
+            extras.putInt(KEY_TCP_PACKET_FAIL_RATE, p.tcpPacketFailRate);
+            extras.putInt(KEY_TCP_METRICS_COLLECTION_PERIOD_MILLIS,
+                    p.tcpMetricsCollectionPeriodMillis);
+            detectionMethod |= DETECTION_METHOD_TCP_METRICS;
+        }
+
+        final Message msg = mConnectivityDiagnosticsHandler.obtainMessage(
+                ConnectivityDiagnosticsHandler.EVENT_DATA_STALL_SUSPECTED, detectionMethod, netId,
+                new Pair<>(p.timestampMillis, extras));
+
+        // NetworkStateTrackerHandler currently doesn't take any actions based on data
+        // stalls so send the message directly to ConnectivityDiagnosticsHandler and avoid
+        // the cost of going through two handlers.
+        mConnectivityDiagnosticsHandler.sendMessage(msg);
+    }
+
+    private boolean hasDataStallDetectionMethod(DataStallReportParcelable p, int detectionMethod) {
+        return (p.detectionMethod & detectionMethod) != 0;
+    }
+
+    private boolean networkRequiresPrivateDnsValidation(NetworkAgentInfo nai) {
+        return isPrivateDnsValidationRequired(nai.networkCapabilities);
+    }
+
+    private void handleFreshlyValidatedNetwork(NetworkAgentInfo nai) {
+        if (nai == null) return;
+        // If the Private DNS mode is opportunistic, reprogram the DNS servers
+        // in order to restart a validation pass from within netd.
+        final PrivateDnsConfig cfg = mDnsManager.getPrivateDnsConfig();
+        if (cfg.useTls && TextUtils.isEmpty(cfg.hostname)) {
+            updateDnses(nai.linkProperties, null, nai.network.getNetId());
+        }
+    }
+
+    private void handlePrivateDnsSettingsChanged() {
+        final PrivateDnsConfig cfg = mDnsManager.getPrivateDnsConfig();
+
+        for (NetworkAgentInfo nai : mNetworkAgentInfos) {
+            handlePerNetworkPrivateDnsConfig(nai, cfg);
+            if (networkRequiresPrivateDnsValidation(nai)) {
+                handleUpdateLinkProperties(nai, new LinkProperties(nai.linkProperties));
+            }
+        }
+    }
+
+    private void handlePerNetworkPrivateDnsConfig(NetworkAgentInfo nai, PrivateDnsConfig cfg) {
+        // Private DNS only ever applies to networks that might provide
+        // Internet access and therefore also require validation.
+        if (!networkRequiresPrivateDnsValidation(nai)) return;
+
+        // Notify the NetworkAgentInfo/NetworkMonitor in case NetworkMonitor needs to cancel or
+        // schedule DNS resolutions. If a DNS resolution is required the
+        // result will be sent back to us.
+        nai.networkMonitor().notifyPrivateDnsChanged(cfg.toParcel());
+
+        // With Private DNS bypass support, we can proceed to update the
+        // Private DNS config immediately, even if we're in strict mode
+        // and have not yet resolved the provider name into a set of IPs.
+        updatePrivateDns(nai, cfg);
+    }
+
+    private void updatePrivateDns(NetworkAgentInfo nai, PrivateDnsConfig newCfg) {
+        mDnsManager.updatePrivateDns(nai.network, newCfg);
+        updateDnses(nai.linkProperties, null, nai.network.getNetId());
+    }
+
+    private void handlePrivateDnsValidationUpdate(PrivateDnsValidationUpdate update) {
+        NetworkAgentInfo nai = getNetworkAgentInfoForNetId(update.netId);
+        if (nai == null) {
+            return;
+        }
+        mDnsManager.updatePrivateDnsValidation(update);
+        handleUpdateLinkProperties(nai, new LinkProperties(nai.linkProperties));
+    }
+
+    private void handleNat64PrefixEvent(int netId, int operation, String prefixAddress,
+            int prefixLength) {
+        NetworkAgentInfo nai = mNetworkForNetId.get(netId);
+        if (nai == null) return;
+
+        log(String.format("NAT64 prefix changed on netId %d: operation=%d, %s/%d",
+                netId, operation, prefixAddress, prefixLength));
+
+        IpPrefix prefix = null;
+        if (operation == IDnsResolverUnsolicitedEventListener.PREFIX_OPERATION_ADDED) {
+            try {
+                prefix = new IpPrefix(InetAddresses.parseNumericAddress(prefixAddress),
+                        prefixLength);
+            } catch (IllegalArgumentException e) {
+                loge("Invalid NAT64 prefix " + prefixAddress + "/" + prefixLength);
+                return;
+            }
+        }
+
+        nai.clatd.setNat64PrefixFromDns(prefix);
+        handleUpdateLinkProperties(nai, new LinkProperties(nai.linkProperties));
+    }
+
+    private void handleCapportApiDataUpdate(@NonNull final NetworkAgentInfo nai,
+            @Nullable final CaptivePortalData data) {
+        nai.capportApiData = data;
+        // CaptivePortalData will be merged into LinkProperties from NetworkAgentInfo
+        handleUpdateLinkProperties(nai, new LinkProperties(nai.linkProperties));
+    }
+
+    /**
+     * Updates the inactivity state from the network requests inside the NAI.
+     * @param nai the agent info to update
+     * @param now the timestamp of the event causing this update
+     * @return whether the network was inactive as a result of this update
+     */
+    private boolean updateInactivityState(@NonNull final NetworkAgentInfo nai, final long now) {
+        // 1. Update the inactivity timer. If it's changed, reschedule or cancel the alarm.
+        // 2. If the network was inactive and there are now requests, unset inactive.
+        // 3. If this network is unneeded (which implies it is not lingering), and there is at least
+        //    one lingered request, set inactive.
+        nai.updateInactivityTimer();
+        if (nai.isInactive() && nai.numForegroundNetworkRequests() > 0) {
+            if (DBG) log("Unsetting inactive " + nai.toShortString());
+            nai.unsetInactive();
+            logNetworkEvent(nai, NetworkEvent.NETWORK_UNLINGER);
+        } else if (unneeded(nai, UnneededFor.LINGER) && nai.getInactivityExpiry() > 0) {
+            if (DBG) {
+                final int lingerTime = (int) (nai.getInactivityExpiry() - now);
+                log("Setting inactive " + nai.toShortString() + " for " + lingerTime + "ms");
+            }
+            nai.setInactive();
+            logNetworkEvent(nai, NetworkEvent.NETWORK_LINGER);
+            return true;
+        }
+        return false;
+    }
+
+    private void handleNetworkAgentRegistered(Message msg) {
+        final NetworkAgentInfo nai = (NetworkAgentInfo) msg.obj;
+        if (!mNetworkAgentInfos.contains(nai)) {
+            return;
+        }
+
+        if (msg.arg1 == NetworkAgentInfo.ARG_AGENT_SUCCESS) {
+            if (VDBG) log("NetworkAgent registered");
+        } else {
+            loge("Error connecting NetworkAgent");
+            mNetworkAgentInfos.remove(nai);
+            if (nai != null) {
+                final boolean wasDefault = isDefaultNetwork(nai);
+                synchronized (mNetworkForNetId) {
+                    mNetworkForNetId.remove(nai.network.getNetId());
+                }
+                mNetIdManager.releaseNetId(nai.network.getNetId());
+                // Just in case.
+                mLegacyTypeTracker.remove(nai, wasDefault);
+            }
+        }
+    }
+
+    private void handleNetworkAgentDisconnected(Message msg) {
+        NetworkAgentInfo nai = (NetworkAgentInfo) msg.obj;
+        if (mNetworkAgentInfos.contains(nai)) {
+            disconnectAndDestroyNetwork(nai);
+        }
+    }
+
+    // Destroys a network, remove references to it from the internal state managed by
+    // ConnectivityService, free its interfaces and clean up.
+    // Must be called on the Handler thread.
+    private void disconnectAndDestroyNetwork(NetworkAgentInfo nai) {
+        ensureRunningOnConnectivityServiceThread();
+        if (DBG) {
+            log(nai.toShortString() + " disconnected, was satisfying " + nai.numNetworkRequests());
+        }
+        // Clear all notifications of this network.
+        mNotifier.clearNotification(nai.network.getNetId());
+        // A network agent has disconnected.
+        // TODO - if we move the logic to the network agent (have them disconnect
+        // because they lost all their requests or because their score isn't good)
+        // then they would disconnect organically, report their new state and then
+        // disconnect the channel.
+        if (nai.networkInfo.isConnected()) {
+            nai.networkInfo.setDetailedState(NetworkInfo.DetailedState.DISCONNECTED,
+                    null, null);
+        }
+        final boolean wasDefault = isDefaultNetwork(nai);
+        if (wasDefault) {
+            mDefaultInetConditionPublished = 0;
+        }
+        notifyIfacesChangedForNetworkStats();
+        // TODO - we shouldn't send CALLBACK_LOST to requests that can be satisfied
+        // by other networks that are already connected. Perhaps that can be done by
+        // sending all CALLBACK_LOST messages (for requests, not listens) at the end
+        // of rematchAllNetworksAndRequests
+        notifyNetworkCallbacks(nai, ConnectivityManager.CALLBACK_LOST);
+        mKeepaliveTracker.handleStopAllKeepalives(nai, SocketKeepalive.ERROR_INVALID_NETWORK);
+
+        mQosCallbackTracker.handleNetworkReleased(nai.network);
+        for (String iface : nai.linkProperties.getAllInterfaceNames()) {
+            // Disable wakeup packet monitoring for each interface.
+            wakeupModifyInterface(iface, nai.networkCapabilities, false);
+        }
+        nai.networkMonitor().notifyNetworkDisconnected();
+        mNetworkAgentInfos.remove(nai);
+        nai.clatd.update();
+        synchronized (mNetworkForNetId) {
+            // Remove the NetworkAgent, but don't mark the netId as
+            // available until we've told netd to delete it below.
+            mNetworkForNetId.remove(nai.network.getNetId());
+        }
+        propagateUnderlyingNetworkCapabilities(nai.network);
+        // Remove all previously satisfied requests.
+        for (int i = 0; i < nai.numNetworkRequests(); i++) {
+            final NetworkRequest request = nai.requestAt(i);
+            final NetworkRequestInfo nri = mNetworkRequests.get(request);
+            final NetworkAgentInfo currentNetwork = nri.getSatisfier();
+            if (currentNetwork != null
+                    && currentNetwork.network.getNetId() == nai.network.getNetId()) {
+                // uid rules for this network will be removed in destroyNativeNetwork(nai).
+                // TODO : setting the satisfier is in fact the job of the rematch. Teach the
+                // rematch not to keep disconnected agents instead of setting it here ; this
+                // will also allow removing updating the offers below.
+                nri.setSatisfier(null, null);
+                for (final NetworkOfferInfo noi : mNetworkOffers) {
+                    informOffer(nri, noi.offer, mNetworkRanker);
+                }
+
+                if (mDefaultRequest == nri) {
+                    // TODO : make battery stats aware that since 2013 multiple interfaces may be
+                    //  active at the same time. For now keep calling this with the default
+                    //  network, because while incorrect this is the closest to the old (also
+                    //  incorrect) behavior.
+                    mNetworkActivityTracker.updateDataActivityTracking(
+                            null /* newNetwork */, nai);
+                    ensureNetworkTransitionWakelock(nai.toShortString());
+                }
+            }
+        }
+        nai.clearInactivityState();
+        // TODO: mLegacyTypeTracker.remove seems redundant given there's a full rematch right after.
+        //  Currently, deleting it breaks tests that check for the default network disconnecting.
+        //  Find out why, fix the rematch code, and delete this.
+        mLegacyTypeTracker.remove(nai, wasDefault);
+        rematchAllNetworksAndRequests();
+        mLingerMonitor.noteDisconnect(nai);
+
+        // Immediate teardown.
+        if (nai.teardownDelayMs == 0) {
+            destroyNetwork(nai);
+            return;
+        }
+
+        // Delayed teardown.
+        try {
+            mNetd.networkSetPermissionForNetwork(nai.network.netId, INetd.PERMISSION_SYSTEM);
+        } catch (RemoteException e) {
+            Log.d(TAG, "Error marking network restricted during teardown: " + e);
+        }
+        mHandler.postDelayed(() -> destroyNetwork(nai), nai.teardownDelayMs);
+    }
+
+    private void destroyNetwork(NetworkAgentInfo nai) {
+        if (nai.created) {
+            // Tell netd to clean up the configuration for this network
+            // (routing rules, DNS, etc).
+            // This may be slow as it requires a lot of netd shelling out to ip and
+            // ip[6]tables to flush routes and remove the incoming packet mark rule, so do it
+            // after we've rematched networks with requests (which might change the default
+            // network or service a new request from an app), so network traffic isn't interrupted
+            // for an unnecessarily long time.
+            destroyNativeNetwork(nai);
+            mDnsManager.removeNetwork(nai.network);
+        }
+        mNetIdManager.releaseNetId(nai.network.getNetId());
+        nai.onNetworkDestroyed();
+    }
+
+    private boolean createNativeNetwork(@NonNull NetworkAgentInfo nai) {
+        try {
+            // This should never fail.  Specifying an already in use NetID will cause failure.
+            final NativeNetworkConfig config;
+            if (nai.isVPN()) {
+                if (getVpnType(nai) == VpnManager.TYPE_VPN_NONE) {
+                    Log.wtf(TAG, "Unable to get VPN type from network " + nai.toShortString());
+                    return false;
+                }
+                config = new NativeNetworkConfig(nai.network.getNetId(), NativeNetworkType.VIRTUAL,
+                        INetd.PERMISSION_NONE,
+                        (nai.networkAgentConfig == null || !nai.networkAgentConfig.allowBypass),
+                        getVpnType(nai));
+            } else {
+                config = new NativeNetworkConfig(nai.network.getNetId(), NativeNetworkType.PHYSICAL,
+                        getNetworkPermission(nai.networkCapabilities), /*secure=*/ false,
+                        VpnManager.TYPE_VPN_NONE);
+            }
+            mNetd.networkCreate(config);
+            mDnsResolver.createNetworkCache(nai.network.getNetId());
+            mDnsManager.updateTransportsForNetwork(nai.network.getNetId(),
+                    nai.networkCapabilities.getTransportTypes());
+            return true;
+        } catch (RemoteException | ServiceSpecificException e) {
+            loge("Error creating network " + nai.toShortString() + ": " + e.getMessage());
+            return false;
+        }
+    }
+
+    private void destroyNativeNetwork(@NonNull NetworkAgentInfo nai) {
+        try {
+            mNetd.networkDestroy(nai.network.getNetId());
+        } catch (RemoteException | ServiceSpecificException e) {
+            loge("Exception destroying network(networkDestroy): " + e);
+        }
+        try {
+            mDnsResolver.destroyNetworkCache(nai.network.getNetId());
+        } catch (RemoteException | ServiceSpecificException e) {
+            loge("Exception destroying network: " + e);
+        }
+    }
+
+    // If this method proves to be too slow then we can maintain a separate
+    // pendingIntent => NetworkRequestInfo map.
+    // This method assumes that every non-null PendingIntent maps to exactly 1 NetworkRequestInfo.
+    private NetworkRequestInfo findExistingNetworkRequestInfo(PendingIntent pendingIntent) {
+        for (Map.Entry<NetworkRequest, NetworkRequestInfo> entry : mNetworkRequests.entrySet()) {
+            PendingIntent existingPendingIntent = entry.getValue().mPendingIntent;
+            if (existingPendingIntent != null &&
+                    existingPendingIntent.intentFilterEquals(pendingIntent)) {
+                return entry.getValue();
+            }
+        }
+        return null;
+    }
+
+    private void handleRegisterNetworkRequestWithIntent(@NonNull final Message msg) {
+        final NetworkRequestInfo nri = (NetworkRequestInfo) (msg.obj);
+        // handleRegisterNetworkRequestWithIntent() doesn't apply to multilayer requests.
+        ensureNotMultilayerRequest(nri, "handleRegisterNetworkRequestWithIntent");
+        final NetworkRequestInfo existingRequest =
+                findExistingNetworkRequestInfo(nri.mPendingIntent);
+        if (existingRequest != null) { // remove the existing request.
+            if (DBG) {
+                log("Replacing " + existingRequest.mRequests.get(0) + " with "
+                        + nri.mRequests.get(0) + " because their intents matched.");
+            }
+            handleReleaseNetworkRequest(existingRequest.mRequests.get(0), mDeps.getCallingUid(),
+                    /* callOnUnavailable */ false);
+        }
+        handleRegisterNetworkRequest(nri);
+    }
+
+    private void handleRegisterNetworkRequest(@NonNull final NetworkRequestInfo nri) {
+        handleRegisterNetworkRequests(Collections.singleton(nri));
+    }
+
+    private void handleRegisterNetworkRequests(@NonNull final Set<NetworkRequestInfo> nris) {
+        ensureRunningOnConnectivityServiceThread();
+        for (final NetworkRequestInfo nri : nris) {
+            mNetworkRequestInfoLogs.log("REGISTER " + nri);
+            for (final NetworkRequest req : nri.mRequests) {
+                mNetworkRequests.put(req, nri);
+                // TODO: Consider update signal strength for other types.
+                if (req.isListen()) {
+                    for (final NetworkAgentInfo network : mNetworkAgentInfos) {
+                        if (req.networkCapabilities.hasSignalStrength()
+                                && network.satisfiesImmutableCapabilitiesOf(req)) {
+                            updateSignalStrengthThresholds(network, "REGISTER", req);
+                        }
+                    }
+                }
+            }
+            // If this NRI has a satisfier already, it is replacing an older request that
+            // has been removed. Track it.
+            final NetworkRequest activeRequest = nri.getActiveRequest();
+            if (null != activeRequest) {
+                // If there is an active request, then for sure there is a satisfier.
+                nri.getSatisfier().addRequest(activeRequest);
+            }
+        }
+
+        rematchAllNetworksAndRequests();
+
+        // Requests that have not been matched to a network will not have been sent to the
+        // providers, because the old satisfier and the new satisfier are the same (null in this
+        // case). Send these requests to the providers.
+        for (final NetworkRequestInfo nri : nris) {
+            for (final NetworkOfferInfo noi : mNetworkOffers) {
+                informOffer(nri, noi.offer, mNetworkRanker);
+            }
+        }
+    }
+
+    private void handleReleaseNetworkRequestWithIntent(@NonNull final PendingIntent pendingIntent,
+            final int callingUid) {
+        final NetworkRequestInfo nri = findExistingNetworkRequestInfo(pendingIntent);
+        if (nri != null) {
+            // handleReleaseNetworkRequestWithIntent() paths don't apply to multilayer requests.
+            ensureNotMultilayerRequest(nri, "handleReleaseNetworkRequestWithIntent");
+            handleReleaseNetworkRequest(
+                    nri.mRequests.get(0),
+                    callingUid,
+                    /* callOnUnavailable */ false);
+        }
+    }
+
+    // Determines whether the network is the best (or could become the best, if it validated), for
+    // none of a particular type of NetworkRequests. The type of NetworkRequests considered depends
+    // on the value of reason:
+    //
+    // - UnneededFor.TEARDOWN: non-listen NetworkRequests. If a network is unneeded for this reason,
+    //   then it should be torn down.
+    // - UnneededFor.LINGER: foreground NetworkRequests. If a network is unneeded for this reason,
+    //   then it should be lingered.
+    private boolean unneeded(NetworkAgentInfo nai, UnneededFor reason) {
+        ensureRunningOnConnectivityServiceThread();
+
+        if (!nai.everConnected || nai.isVPN() || nai.isInactive()
+                || nai.getScore().getKeepConnectedReason() != NetworkScore.KEEP_CONNECTED_NONE) {
+            return false;
+        }
+
+        final int numRequests;
+        switch (reason) {
+            case TEARDOWN:
+                numRequests = nai.numRequestNetworkRequests();
+                break;
+            case LINGER:
+                numRequests = nai.numForegroundNetworkRequests();
+                break;
+            default:
+                Log.wtf(TAG, "Invalid reason. Cannot happen.");
+                return true;
+        }
+
+        if (numRequests > 0) return false;
+
+        for (NetworkRequestInfo nri : mNetworkRequests.values()) {
+            if (reason == UnneededFor.LINGER
+                    && !nri.isMultilayerRequest()
+                    && nri.mRequests.get(0).isBackgroundRequest()) {
+                // Background requests don't affect lingering.
+                continue;
+            }
+
+            if (isNetworkPotentialSatisfier(nai, nri)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private boolean isNetworkPotentialSatisfier(
+            @NonNull final NetworkAgentInfo candidate, @NonNull final NetworkRequestInfo nri) {
+        // listen requests won't keep up a network satisfying it. If this is not a multilayer
+        // request, return immediately. For multilayer requests, check to see if any of the
+        // multilayer requests may have a potential satisfier.
+        if (!nri.isMultilayerRequest() && (nri.mRequests.get(0).isListen()
+                || nri.mRequests.get(0).isListenForBest())) {
+            return false;
+        }
+        for (final NetworkRequest req : nri.mRequests) {
+            // This multilayer listen request is satisfied therefore no further requests need to be
+            // evaluated deeming this network not a potential satisfier.
+            if ((req.isListen() || req.isListenForBest()) && nri.getActiveRequest() == req) {
+                return false;
+            }
+            // As non-multilayer listen requests have already returned, the below would only happen
+            // for a multilayer request therefore continue to the next request if available.
+            if (req.isListen() || req.isListenForBest()) {
+                continue;
+            }
+            // If this Network is already the highest scoring Network for a request, or if
+            // there is hope for it to become one if it validated, then it is needed.
+            if (candidate.satisfies(req)) {
+                // As soon as a network is found that satisfies a request, return. Specifically for
+                // multilayer requests, returning as soon as a NetworkAgentInfo satisfies a request
+                // is important so as to not evaluate lower priority requests further in
+                // nri.mRequests.
+                final NetworkAgentInfo champion = req.equals(nri.getActiveRequest())
+                        ? nri.getSatisfier() : null;
+                // Note that this catches two important cases:
+                // 1. Unvalidated cellular will not be reaped when unvalidated WiFi
+                //    is currently satisfying the request.  This is desirable when
+                //    cellular ends up validating but WiFi does not.
+                // 2. Unvalidated WiFi will not be reaped when validated cellular
+                //    is currently satisfying the request.  This is desirable when
+                //    WiFi ends up validating and out scoring cellular.
+                return mNetworkRanker.mightBeat(req, champion, candidate.getValidatedScoreable());
+            }
+        }
+
+        return false;
+    }
+
+    private NetworkRequestInfo getNriForAppRequest(
+            NetworkRequest request, int callingUid, String requestedOperation) {
+        // Looking up the app passed param request in mRequests isn't possible since it may return
+        // null for a request managed by a per-app default. Therefore use getNriForAppRequest() to
+        // do the lookup since that will also find per-app default managed requests.
+        // Additionally, this lookup needs to be relatively fast (hence the lookup optimization)
+        // to avoid potential race conditions when validating a package->uid mapping when sending
+        // the callback on the very low-chance that an application shuts down prior to the callback
+        // being sent.
+        final NetworkRequestInfo nri = mNetworkRequests.get(request) != null
+                ? mNetworkRequests.get(request) : getNriForAppRequest(request);
+
+        if (nri != null) {
+            if (Process.SYSTEM_UID != callingUid && nri.mUid != callingUid) {
+                log(String.format("UID %d attempted to %s for unowned request %s",
+                        callingUid, requestedOperation, nri));
+                return null;
+            }
+        }
+
+        return nri;
+    }
+
+    private void ensureNotMultilayerRequest(@NonNull final NetworkRequestInfo nri,
+            final String callingMethod) {
+        if (nri.isMultilayerRequest()) {
+            throw new IllegalStateException(
+                    callingMethod + " does not support multilayer requests.");
+        }
+    }
+
+    private void handleTimedOutNetworkRequest(@NonNull final NetworkRequestInfo nri) {
+        ensureRunningOnConnectivityServiceThread();
+        // handleTimedOutNetworkRequest() is part of the requestNetwork() flow which works off of a
+        // single NetworkRequest and thus does not apply to multilayer requests.
+        ensureNotMultilayerRequest(nri, "handleTimedOutNetworkRequest");
+        if (mNetworkRequests.get(nri.mRequests.get(0)) == null) {
+            return;
+        }
+        if (nri.isBeingSatisfied()) {
+            return;
+        }
+        if (VDBG || (DBG && nri.mRequests.get(0).isRequest())) {
+            log("releasing " + nri.mRequests.get(0) + " (timeout)");
+        }
+        handleRemoveNetworkRequest(nri);
+        callCallbackForRequest(
+                nri, null, ConnectivityManager.CALLBACK_UNAVAIL, 0);
+    }
+
+    private void handleReleaseNetworkRequest(@NonNull final NetworkRequest request,
+            final int callingUid,
+            final boolean callOnUnavailable) {
+        final NetworkRequestInfo nri =
+                getNriForAppRequest(request, callingUid, "release NetworkRequest");
+        if (nri == null) {
+            return;
+        }
+        if (VDBG || (DBG && request.isRequest())) {
+            log("releasing " + request + " (release request)");
+        }
+        handleRemoveNetworkRequest(nri);
+        if (callOnUnavailable) {
+            callCallbackForRequest(nri, null, ConnectivityManager.CALLBACK_UNAVAIL, 0);
+        }
+    }
+
+    private void handleRemoveNetworkRequest(@NonNull final NetworkRequestInfo nri) {
+        ensureRunningOnConnectivityServiceThread();
+        nri.unlinkDeathRecipient();
+        for (final NetworkRequest req : nri.mRequests) {
+            mNetworkRequests.remove(req);
+            if (req.isListen()) {
+                removeListenRequestFromNetworks(req);
+            }
+        }
+        if (mDefaultNetworkRequests.remove(nri)) {
+            // If this request was one of the defaults, then the UID rules need to be updated
+            // WARNING : if the app(s) for which this network request is the default are doing
+            // traffic, this will kill their connected sockets, even if an equivalent request
+            // is going to be reinstated right away ; unconnected traffic will go on the default
+            // until the new default is set, which will happen very soon.
+            // TODO : The only way out of this is to diff old defaults and new defaults, and only
+            // remove ranges for those requests that won't have a replacement
+            final NetworkAgentInfo satisfier = nri.getSatisfier();
+            if (null != satisfier) {
+                try {
+                    mNetd.networkRemoveUidRanges(satisfier.network.getNetId(),
+                            toUidRangeStableParcels(nri.getUids()));
+                } catch (RemoteException e) {
+                    loge("Exception setting network preference default network", e);
+                }
+            }
+        }
+        nri.decrementRequestCount();
+        mNetworkRequestInfoLogs.log("RELEASE " + nri);
+
+        if (null != nri.getActiveRequest()) {
+            if (!nri.getActiveRequest().isListen()) {
+                removeSatisfiedNetworkRequestFromNetwork(nri);
+            } else {
+                nri.setSatisfier(null, null);
+            }
+        }
+
+        // For all outstanding offers, cancel any of the layers of this NRI that used to be
+        // needed for this offer.
+        for (final NetworkOfferInfo noi : mNetworkOffers) {
+            for (final NetworkRequest req : nri.mRequests) {
+                if (req.isRequest() && noi.offer.neededFor(req)) {
+                    noi.offer.onNetworkUnneeded(req);
+                }
+            }
+        }
+    }
+
+    private void handleRemoveNetworkRequests(@NonNull final Set<NetworkRequestInfo> nris) {
+        for (final NetworkRequestInfo nri : nris) {
+            if (mDefaultRequest == nri) {
+                // Make sure we never remove the default request.
+                continue;
+            }
+            handleRemoveNetworkRequest(nri);
+        }
+    }
+
+    private void removeListenRequestFromNetworks(@NonNull final NetworkRequest req) {
+        // listens don't have a singular affected Network. Check all networks to see
+        // if this listen request applies and remove it.
+        for (final NetworkAgentInfo nai : mNetworkAgentInfos) {
+            nai.removeRequest(req.requestId);
+            if (req.networkCapabilities.hasSignalStrength()
+                    && nai.satisfiesImmutableCapabilitiesOf(req)) {
+                updateSignalStrengthThresholds(nai, "RELEASE", req);
+            }
+        }
+    }
+
+    /**
+     * Remove a NetworkRequestInfo's satisfied request from its 'satisfier' (NetworkAgentInfo) and
+     * manage the necessary upkeep (linger, teardown networks, etc.) when doing so.
+     * @param nri the NetworkRequestInfo to disassociate from its current NetworkAgentInfo
+     */
+    private void removeSatisfiedNetworkRequestFromNetwork(@NonNull final NetworkRequestInfo nri) {
+        boolean wasKept = false;
+        final NetworkAgentInfo nai = nri.getSatisfier();
+        if (nai != null) {
+            final int requestLegacyType = nri.getActiveRequest().legacyType;
+            final boolean wasBackgroundNetwork = nai.isBackgroundNetwork();
+            nai.removeRequest(nri.getActiveRequest().requestId);
+            if (VDBG || DDBG) {
+                log(" Removing from current network " + nai.toShortString()
+                        + ", leaving " + nai.numNetworkRequests() + " requests.");
+            }
+            // If there are still lingered requests on this network, don't tear it down,
+            // but resume lingering instead.
+            final long now = SystemClock.elapsedRealtime();
+            if (updateInactivityState(nai, now)) {
+                notifyNetworkLosing(nai, now);
+            }
+            if (unneeded(nai, UnneededFor.TEARDOWN)) {
+                if (DBG) log("no live requests for " + nai.toShortString() + "; disconnecting");
+                teardownUnneededNetwork(nai);
+            } else {
+                wasKept = true;
+            }
+            nri.setSatisfier(null, null);
+            if (!wasBackgroundNetwork && nai.isBackgroundNetwork()) {
+                // Went from foreground to background.
+                updateCapabilitiesForNetwork(nai);
+            }
+
+            // Maintain the illusion.  When this request arrived, we might have pretended
+            // that a network connected to serve it, even though the network was already
+            // connected.  Now that this request has gone away, we might have to pretend
+            // that the network disconnected.  LegacyTypeTracker will generate that
+            // phantom disconnect for this type.
+            if (requestLegacyType != TYPE_NONE) {
+                boolean doRemove = true;
+                if (wasKept) {
+                    // check if any of the remaining requests for this network are for the
+                    // same legacy type - if so, don't remove the nai
+                    for (int i = 0; i < nai.numNetworkRequests(); i++) {
+                        NetworkRequest otherRequest = nai.requestAt(i);
+                        if (otherRequest.legacyType == requestLegacyType
+                                && otherRequest.isRequest()) {
+                            if (DBG) log(" still have other legacy request - leaving");
+                            doRemove = false;
+                        }
+                    }
+                }
+
+                if (doRemove) {
+                    mLegacyTypeTracker.remove(requestLegacyType, nai, false);
+                }
+            }
+        }
+    }
+
+    private PerUidCounter getRequestCounter(NetworkRequestInfo nri) {
+        return checkAnyPermissionOf(
+                nri.mPid, nri.mUid, NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK)
+                ? mSystemNetworkRequestCounter : mNetworkRequestCounter;
+    }
+
+    @Override
+    public void setAcceptUnvalidated(Network network, boolean accept, boolean always) {
+        enforceNetworkStackSettingsOrSetup();
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_SET_ACCEPT_UNVALIDATED,
+                encodeBool(accept), encodeBool(always), network));
+    }
+
+    @Override
+    public void setAcceptPartialConnectivity(Network network, boolean accept, boolean always) {
+        enforceNetworkStackSettingsOrSetup();
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_SET_ACCEPT_PARTIAL_CONNECTIVITY,
+                encodeBool(accept), encodeBool(always), network));
+    }
+
+    @Override
+    public void setAvoidUnvalidated(Network network) {
+        enforceNetworkStackSettingsOrSetup();
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_SET_AVOID_UNVALIDATED, network));
+    }
+
+    private void handleSetAcceptUnvalidated(Network network, boolean accept, boolean always) {
+        if (DBG) log("handleSetAcceptUnvalidated network=" + network +
+                " accept=" + accept + " always=" + always);
+
+        NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+        if (nai == null) {
+            // Nothing to do.
+            return;
+        }
+
+        if (nai.everValidated) {
+            // The network validated while the dialog box was up. Take no action.
+            return;
+        }
+
+        if (!nai.networkAgentConfig.explicitlySelected) {
+            Log.wtf(TAG, "BUG: setAcceptUnvalidated non non-explicitly selected network");
+        }
+
+        if (accept != nai.networkAgentConfig.acceptUnvalidated) {
+            nai.networkAgentConfig.acceptUnvalidated = accept;
+            // If network becomes partial connectivity and user already accepted to use this
+            // network, we should respect the user's option and don't need to popup the
+            // PARTIAL_CONNECTIVITY notification to user again.
+            nai.networkAgentConfig.acceptPartialConnectivity = accept;
+            nai.updateScoreForNetworkAgentUpdate();
+            rematchAllNetworksAndRequests();
+        }
+
+        if (always) {
+            nai.onSaveAcceptUnvalidated(accept);
+        }
+
+        if (!accept) {
+            // Tell the NetworkAgent to not automatically reconnect to the network.
+            nai.onPreventAutomaticReconnect();
+            // Teardown the network.
+            teardownUnneededNetwork(nai);
+        }
+
+    }
+
+    private void handleSetAcceptPartialConnectivity(Network network, boolean accept,
+            boolean always) {
+        if (DBG) {
+            log("handleSetAcceptPartialConnectivity network=" + network + " accept=" + accept
+                    + " always=" + always);
+        }
+
+        final NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+        if (nai == null) {
+            // Nothing to do.
+            return;
+        }
+
+        if (nai.lastValidated) {
+            // The network validated while the dialog box was up. Take no action.
+            return;
+        }
+
+        if (accept != nai.networkAgentConfig.acceptPartialConnectivity) {
+            nai.networkAgentConfig.acceptPartialConnectivity = accept;
+        }
+
+        // TODO: Use the current design or save the user choice into IpMemoryStore.
+        if (always) {
+            nai.onSaveAcceptUnvalidated(accept);
+        }
+
+        if (!accept) {
+            // Tell the NetworkAgent to not automatically reconnect to the network.
+            nai.onPreventAutomaticReconnect();
+            // Tear down the network.
+            teardownUnneededNetwork(nai);
+        } else {
+            // Inform NetworkMonitor that partial connectivity is acceptable. This will likely
+            // result in a partial connectivity result which will be processed by
+            // maybeHandleNetworkMonitorMessage.
+            //
+            // TODO: NetworkMonitor does not refer to the "never ask again" bit. The bit is stored
+            // per network. Therefore, NetworkMonitor may still do https probe.
+            nai.networkMonitor().setAcceptPartialConnectivity();
+        }
+    }
+
+    private void handleSetAvoidUnvalidated(Network network) {
+        NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+        if (nai == null || nai.lastValidated) {
+            // Nothing to do. The network either disconnected or revalidated.
+            return;
+        }
+        if (!nai.avoidUnvalidated) {
+            nai.avoidUnvalidated = true;
+            nai.updateScoreForNetworkAgentUpdate();
+            rematchAllNetworksAndRequests();
+        }
+    }
+
+    private void scheduleUnvalidatedPrompt(NetworkAgentInfo nai) {
+        if (VDBG) log("scheduleUnvalidatedPrompt " + nai.network);
+        mHandler.sendMessageDelayed(
+                mHandler.obtainMessage(EVENT_PROMPT_UNVALIDATED, nai.network),
+                PROMPT_UNVALIDATED_DELAY_MS);
+    }
+
+    @Override
+    public void startCaptivePortalApp(Network network) {
+        enforceNetworkStackOrSettingsPermission();
+        mHandler.post(() -> {
+            NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+            if (nai == null) return;
+            if (!nai.networkCapabilities.hasCapability(NET_CAPABILITY_CAPTIVE_PORTAL)) return;
+            nai.networkMonitor().launchCaptivePortalApp();
+        });
+    }
+
+    /**
+     * NetworkStack endpoint to start the captive portal app. The NetworkStack needs to use this
+     * endpoint as it does not have INTERACT_ACROSS_USERS_FULL itself.
+     * @param network Network on which the captive portal was detected.
+     * @param appExtras Bundle to use as intent extras for the captive portal application.
+     *                  Must be treated as opaque to avoid preventing the captive portal app to
+     *                  update its arguments.
+     */
+    @Override
+    public void startCaptivePortalAppInternal(Network network, Bundle appExtras) {
+        mContext.enforceCallingOrSelfPermission(NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK,
+                "ConnectivityService");
+
+        final Intent appIntent = new Intent(ConnectivityManager.ACTION_CAPTIVE_PORTAL_SIGN_IN);
+        appIntent.putExtras(appExtras);
+        appIntent.putExtra(ConnectivityManager.EXTRA_CAPTIVE_PORTAL,
+                new CaptivePortal(new CaptivePortalImpl(network).asBinder()));
+        appIntent.setFlags(Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT | Intent.FLAG_ACTIVITY_NEW_TASK);
+
+        final long token = Binder.clearCallingIdentity();
+        try {
+            mContext.startActivityAsUser(appIntent, UserHandle.CURRENT);
+        } finally {
+            Binder.restoreCallingIdentity(token);
+        }
+    }
+
+    private class CaptivePortalImpl extends ICaptivePortal.Stub {
+        private final Network mNetwork;
+
+        private CaptivePortalImpl(Network network) {
+            mNetwork = network;
+        }
+
+        @Override
+        public void appResponse(final int response) {
+            if (response == CaptivePortal.APP_RETURN_WANTED_AS_IS) {
+                enforceSettingsPermission();
+            }
+
+            final NetworkMonitorManager nm = getNetworkMonitorManager(mNetwork);
+            if (nm == null) return;
+            nm.notifyCaptivePortalAppFinished(response);
+        }
+
+        @Override
+        public void appRequest(final int request) {
+            final NetworkMonitorManager nm = getNetworkMonitorManager(mNetwork);
+            if (nm == null) return;
+
+            if (request == CaptivePortal.APP_REQUEST_REEVALUATION_REQUIRED) {
+                checkNetworkStackPermission();
+                nm.forceReevaluation(mDeps.getCallingUid());
+            }
+        }
+
+        @Nullable
+        private NetworkMonitorManager getNetworkMonitorManager(final Network network) {
+            // getNetworkAgentInfoForNetwork is thread-safe
+            final NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+            if (nai == null) return null;
+
+            // nai.networkMonitor() is thread-safe
+            return nai.networkMonitor();
+        }
+    }
+
+    public boolean avoidBadWifi() {
+        return mMultinetworkPolicyTracker.getAvoidBadWifi();
+    }
+
+    /**
+     * Return whether the device should maintain continuous, working connectivity by switching away
+     * from WiFi networks having no connectivity.
+     * @see MultinetworkPolicyTracker#getAvoidBadWifi()
+     */
+    public boolean shouldAvoidBadWifi() {
+        if (!checkNetworkStackPermission()) {
+            throw new SecurityException("avoidBadWifi requires NETWORK_STACK permission");
+        }
+        return avoidBadWifi();
+    }
+
+    private void updateAvoidBadWifi() {
+        for (final NetworkAgentInfo nai : mNetworkAgentInfos) {
+            nai.updateScoreForNetworkAgentUpdate();
+        }
+        rematchAllNetworksAndRequests();
+    }
+
+    // TODO: Evaluate whether this is of interest to other consumers of
+    // MultinetworkPolicyTracker and worth moving out of here.
+    private void dumpAvoidBadWifiSettings(IndentingPrintWriter pw) {
+        final boolean configRestrict = mMultinetworkPolicyTracker.configRestrictsAvoidBadWifi();
+        if (!configRestrict) {
+            pw.println("Bad Wi-Fi avoidance: unrestricted");
+            return;
+        }
+
+        pw.println("Bad Wi-Fi avoidance: " + avoidBadWifi());
+        pw.increaseIndent();
+        pw.println("Config restrict:   " + configRestrict);
+
+        final String value = mMultinetworkPolicyTracker.getAvoidBadWifiSetting();
+        String description;
+        // Can't use a switch statement because strings are legal case labels, but null is not.
+        if ("0".equals(value)) {
+            description = "get stuck";
+        } else if (value == null) {
+            description = "prompt";
+        } else if ("1".equals(value)) {
+            description = "avoid";
+        } else {
+            description = value + " (?)";
+        }
+        pw.println("User setting:      " + description);
+        pw.println("Network overrides:");
+        pw.increaseIndent();
+        for (NetworkAgentInfo nai : networksSortedById()) {
+            if (nai.avoidUnvalidated) {
+                pw.println(nai.toShortString());
+            }
+        }
+        pw.decreaseIndent();
+        pw.decreaseIndent();
+    }
+
+    // TODO: This method is copied from TetheringNotificationUpdater. Should have a utility class to
+    // unify the method.
+    private static @NonNull String getSettingsPackageName(@NonNull final PackageManager pm) {
+        final Intent settingsIntent = new Intent(Settings.ACTION_SETTINGS);
+        final ComponentName settingsComponent = settingsIntent.resolveActivity(pm);
+        return settingsComponent != null
+                ? settingsComponent.getPackageName() : "com.android.settings";
+    }
+
+    private void showNetworkNotification(NetworkAgentInfo nai, NotificationType type) {
+        final String action;
+        final boolean highPriority;
+        switch (type) {
+            case NO_INTERNET:
+                action = ConnectivityManager.ACTION_PROMPT_UNVALIDATED;
+                // High priority because it is only displayed for explicitly selected networks.
+                highPriority = true;
+                break;
+            case PRIVATE_DNS_BROKEN:
+                action = Settings.ACTION_WIRELESS_SETTINGS;
+                // High priority because we should let user know why there is no internet.
+                highPriority = true;
+                break;
+            case LOST_INTERNET:
+                action = ConnectivityManager.ACTION_PROMPT_LOST_VALIDATION;
+                // High priority because it could help the user avoid unexpected data usage.
+                highPriority = true;
+                break;
+            case PARTIAL_CONNECTIVITY:
+                action = ConnectivityManager.ACTION_PROMPT_PARTIAL_CONNECTIVITY;
+                // Don't bother the user with a high-priority notification if the network was not
+                // explicitly selected by the user.
+                highPriority = nai.networkAgentConfig.explicitlySelected;
+                break;
+            default:
+                Log.wtf(TAG, "Unknown notification type " + type);
+                return;
+        }
+
+        Intent intent = new Intent(action);
+        if (type != NotificationType.PRIVATE_DNS_BROKEN) {
+            intent.putExtra(ConnectivityManager.EXTRA_NETWORK, nai.network);
+            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
+            // Some OEMs have their own Settings package. Thus, need to get the current using
+            // Settings package name instead of just use default name "com.android.settings".
+            final String settingsPkgName = getSettingsPackageName(mContext.getPackageManager());
+            intent.setClassName(settingsPkgName,
+                    settingsPkgName + ".wifi.WifiNoInternetDialog");
+        }
+
+        PendingIntent pendingIntent = PendingIntent.getActivity(
+                mContext.createContextAsUser(UserHandle.CURRENT, 0 /* flags */),
+                0 /* requestCode */,
+                intent,
+                PendingIntent.FLAG_CANCEL_CURRENT | PendingIntent.FLAG_IMMUTABLE);
+
+        mNotifier.showNotification(
+                nai.network.getNetId(), type, nai, null, pendingIntent, highPriority);
+    }
+
+    private boolean shouldPromptUnvalidated(NetworkAgentInfo nai) {
+        // Don't prompt if the network is validated, and don't prompt on captive portals
+        // because we're already prompting the user to sign in.
+        if (nai.everValidated || nai.everCaptivePortalDetected) {
+            return false;
+        }
+
+        // If a network has partial connectivity, always prompt unless the user has already accepted
+        // partial connectivity and selected don't ask again. This ensures that if the device
+        // automatically connects to a network that has partial Internet access, the user will
+        // always be able to use it, either because they've already chosen "don't ask again" or
+        // because we have prompt them.
+        if (nai.partialConnectivity && !nai.networkAgentConfig.acceptPartialConnectivity) {
+            return true;
+        }
+
+        // If a network has no Internet access, only prompt if the network was explicitly selected
+        // and if the user has not already told us to use the network regardless of whether it
+        // validated or not.
+        if (nai.networkAgentConfig.explicitlySelected
+                && !nai.networkAgentConfig.acceptUnvalidated) {
+            return true;
+        }
+
+        return false;
+    }
+
+    private void handlePromptUnvalidated(Network network) {
+        if (VDBG || DDBG) log("handlePromptUnvalidated " + network);
+        NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+
+        if (nai == null || !shouldPromptUnvalidated(nai)) {
+            return;
+        }
+
+        // Stop automatically reconnecting to this network in the future. Automatically connecting
+        // to a network that provides no or limited connectivity is not useful, because the user
+        // cannot use that network except through the notification shown by this method, and the
+        // notification is only shown if the network is explicitly selected by the user.
+        nai.onPreventAutomaticReconnect();
+
+        // TODO: Evaluate if it's needed to wait 8 seconds for triggering notification when
+        // NetworkMonitor detects the network is partial connectivity. Need to change the design to
+        // popup the notification immediately when the network is partial connectivity.
+        if (nai.partialConnectivity) {
+            showNetworkNotification(nai, NotificationType.PARTIAL_CONNECTIVITY);
+        } else {
+            showNetworkNotification(nai, NotificationType.NO_INTERNET);
+        }
+    }
+
+    private void handleNetworkUnvalidated(NetworkAgentInfo nai) {
+        NetworkCapabilities nc = nai.networkCapabilities;
+        if (DBG) log("handleNetworkUnvalidated " + nai.toShortString() + " cap=" + nc);
+
+        if (!nc.hasTransport(NetworkCapabilities.TRANSPORT_WIFI)) {
+            return;
+        }
+
+        if (mMultinetworkPolicyTracker.shouldNotifyWifiUnvalidated()) {
+            showNetworkNotification(nai, NotificationType.LOST_INTERNET);
+        }
+    }
+
+    @Override
+    public int getMultipathPreference(Network network) {
+        enforceAccessPermission();
+
+        NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+        if (nai != null && nai.networkCapabilities
+                .hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_METERED)) {
+            return ConnectivityManager.MULTIPATH_PREFERENCE_UNMETERED;
+        }
+
+        final NetworkPolicyManager netPolicyManager =
+                 mContext.getSystemService(NetworkPolicyManager.class);
+
+        final long token = Binder.clearCallingIdentity();
+        final int networkPreference;
+        try {
+            networkPreference = netPolicyManager.getMultipathPreference(network);
+        } finally {
+            Binder.restoreCallingIdentity(token);
+        }
+        if (networkPreference != 0) {
+            return networkPreference;
+        }
+        return mMultinetworkPolicyTracker.getMeteredMultipathPreference();
+    }
+
+    @Override
+    public NetworkRequest getDefaultRequest() {
+        return mDefaultRequest.mRequests.get(0);
+    }
+
+    private class InternalHandler extends Handler {
+        public InternalHandler(Looper looper) {
+            super(looper);
+        }
+
+        @Override
+        public void handleMessage(Message msg) {
+            switch (msg.what) {
+                case EVENT_EXPIRE_NET_TRANSITION_WAKELOCK:
+                case EVENT_CLEAR_NET_TRANSITION_WAKELOCK: {
+                    handleReleaseNetworkTransitionWakelock(msg.what);
+                    break;
+                }
+                case EVENT_APPLY_GLOBAL_HTTP_PROXY: {
+                    mProxyTracker.loadDeprecatedGlobalHttpProxy();
+                    break;
+                }
+                case EVENT_PROXY_HAS_CHANGED: {
+                    final Pair<Network, ProxyInfo> arg = (Pair<Network, ProxyInfo>) msg.obj;
+                    handleApplyDefaultProxy(arg.second);
+                    break;
+                }
+                case EVENT_REGISTER_NETWORK_PROVIDER: {
+                    handleRegisterNetworkProvider((NetworkProviderInfo) msg.obj);
+                    break;
+                }
+                case EVENT_UNREGISTER_NETWORK_PROVIDER: {
+                    handleUnregisterNetworkProvider((Messenger) msg.obj);
+                    break;
+                }
+                case EVENT_REGISTER_NETWORK_OFFER: {
+                    handleRegisterNetworkOffer((NetworkOffer) msg.obj);
+                    break;
+                }
+                case EVENT_UNREGISTER_NETWORK_OFFER: {
+                    final NetworkOfferInfo offer =
+                            findNetworkOfferInfoByCallback((INetworkOfferCallback) msg.obj);
+                    if (null != offer) {
+                        handleUnregisterNetworkOffer(offer);
+                    }
+                    break;
+                }
+                case EVENT_REGISTER_NETWORK_AGENT: {
+                    final Pair<NetworkAgentInfo, INetworkMonitor> arg =
+                            (Pair<NetworkAgentInfo, INetworkMonitor>) msg.obj;
+                    handleRegisterNetworkAgent(arg.first, arg.second);
+                    break;
+                }
+                case EVENT_REGISTER_NETWORK_REQUEST:
+                case EVENT_REGISTER_NETWORK_LISTENER: {
+                    handleRegisterNetworkRequest((NetworkRequestInfo) msg.obj);
+                    break;
+                }
+                case EVENT_REGISTER_NETWORK_REQUEST_WITH_INTENT:
+                case EVENT_REGISTER_NETWORK_LISTENER_WITH_INTENT: {
+                    handleRegisterNetworkRequestWithIntent(msg);
+                    break;
+                }
+                case EVENT_TIMEOUT_NETWORK_REQUEST: {
+                    NetworkRequestInfo nri = (NetworkRequestInfo) msg.obj;
+                    handleTimedOutNetworkRequest(nri);
+                    break;
+                }
+                case EVENT_RELEASE_NETWORK_REQUEST_WITH_INTENT: {
+                    handleReleaseNetworkRequestWithIntent((PendingIntent) msg.obj, msg.arg1);
+                    break;
+                }
+                case EVENT_RELEASE_NETWORK_REQUEST: {
+                    handleReleaseNetworkRequest((NetworkRequest) msg.obj, msg.arg1,
+                            /* callOnUnavailable */ false);
+                    break;
+                }
+                case EVENT_SET_ACCEPT_UNVALIDATED: {
+                    Network network = (Network) msg.obj;
+                    handleSetAcceptUnvalidated(network, toBool(msg.arg1), toBool(msg.arg2));
+                    break;
+                }
+                case EVENT_SET_ACCEPT_PARTIAL_CONNECTIVITY: {
+                    Network network = (Network) msg.obj;
+                    handleSetAcceptPartialConnectivity(network, toBool(msg.arg1),
+                            toBool(msg.arg2));
+                    break;
+                }
+                case EVENT_SET_AVOID_UNVALIDATED: {
+                    handleSetAvoidUnvalidated((Network) msg.obj);
+                    break;
+                }
+                case EVENT_PROMPT_UNVALIDATED: {
+                    handlePromptUnvalidated((Network) msg.obj);
+                    break;
+                }
+                case EVENT_CONFIGURE_ALWAYS_ON_NETWORKS: {
+                    handleConfigureAlwaysOnNetworks();
+                    break;
+                }
+                // Sent by KeepaliveTracker to process an app request on the state machine thread.
+                case NetworkAgent.CMD_START_SOCKET_KEEPALIVE: {
+                    mKeepaliveTracker.handleStartKeepalive(msg);
+                    break;
+                }
+                // Sent by KeepaliveTracker to process an app request on the state machine thread.
+                case NetworkAgent.CMD_STOP_SOCKET_KEEPALIVE: {
+                    NetworkAgentInfo nai = getNetworkAgentInfoForNetwork((Network) msg.obj);
+                    int slot = msg.arg1;
+                    int reason = msg.arg2;
+                    mKeepaliveTracker.handleStopKeepalive(nai, slot, reason);
+                    break;
+                }
+                case EVENT_REVALIDATE_NETWORK: {
+                    handleReportNetworkConnectivity((Network) msg.obj, msg.arg1, toBool(msg.arg2));
+                    break;
+                }
+                case EVENT_PRIVATE_DNS_SETTINGS_CHANGED:
+                    handlePrivateDnsSettingsChanged();
+                    break;
+                case EVENT_PRIVATE_DNS_VALIDATION_UPDATE:
+                    handlePrivateDnsValidationUpdate(
+                            (PrivateDnsValidationUpdate) msg.obj);
+                    break;
+                case EVENT_UID_BLOCKED_REASON_CHANGED:
+                    handleUidBlockedReasonChanged(msg.arg1, msg.arg2);
+                    break;
+                case EVENT_SET_REQUIRE_VPN_FOR_UIDS:
+                    handleSetRequireVpnForUids(toBool(msg.arg1), (UidRange[]) msg.obj);
+                    break;
+                case EVENT_SET_OEM_NETWORK_PREFERENCE: {
+                    final Pair<OemNetworkPreferences, IOnCompleteListener> arg =
+                            (Pair<OemNetworkPreferences, IOnCompleteListener>) msg.obj;
+                    handleSetOemNetworkPreference(arg.first, arg.second);
+                    break;
+                }
+                case EVENT_SET_PROFILE_NETWORK_PREFERENCE: {
+                    final Pair<ProfileNetworkPreferences.Preference, IOnCompleteListener> arg =
+                            (Pair<ProfileNetworkPreferences.Preference, IOnCompleteListener>)
+                                    msg.obj;
+                    handleSetProfileNetworkPreference(arg.first, arg.second);
+                    break;
+                }
+                case EVENT_REPORT_NETWORK_ACTIVITY:
+                    mNetworkActivityTracker.handleReportNetworkActivity();
+                    break;
+            }
+        }
+    }
+
+    @Override
+    @Deprecated
+    public int getLastTetherError(String iface) {
+        final TetheringManager tm = (TetheringManager) mContext.getSystemService(
+                Context.TETHERING_SERVICE);
+        return tm.getLastTetherError(iface);
+    }
+
+    @Override
+    @Deprecated
+    public String[] getTetherableIfaces() {
+        final TetheringManager tm = (TetheringManager) mContext.getSystemService(
+                Context.TETHERING_SERVICE);
+        return tm.getTetherableIfaces();
+    }
+
+    @Override
+    @Deprecated
+    public String[] getTetheredIfaces() {
+        final TetheringManager tm = (TetheringManager) mContext.getSystemService(
+                Context.TETHERING_SERVICE);
+        return tm.getTetheredIfaces();
+    }
+
+
+    @Override
+    @Deprecated
+    public String[] getTetheringErroredIfaces() {
+        final TetheringManager tm = (TetheringManager) mContext.getSystemService(
+                Context.TETHERING_SERVICE);
+
+        return tm.getTetheringErroredIfaces();
+    }
+
+    @Override
+    @Deprecated
+    public String[] getTetherableUsbRegexs() {
+        final TetheringManager tm = (TetheringManager) mContext.getSystemService(
+                Context.TETHERING_SERVICE);
+
+        return tm.getTetherableUsbRegexs();
+    }
+
+    @Override
+    @Deprecated
+    public String[] getTetherableWifiRegexs() {
+        final TetheringManager tm = (TetheringManager) mContext.getSystemService(
+                Context.TETHERING_SERVICE);
+        return tm.getTetherableWifiRegexs();
+    }
+
+    // Called when we lose the default network and have no replacement yet.
+    // This will automatically be cleared after X seconds or a new default network
+    // becomes CONNECTED, whichever happens first.  The timer is started by the
+    // first caller and not restarted by subsequent callers.
+    private void ensureNetworkTransitionWakelock(String forWhom) {
+        synchronized (this) {
+            if (mNetTransitionWakeLock.isHeld()) {
+                return;
+            }
+            mNetTransitionWakeLock.acquire();
+            mLastWakeLockAcquireTimestamp = SystemClock.elapsedRealtime();
+            mTotalWakelockAcquisitions++;
+        }
+        mWakelockLogs.log("ACQUIRE for " + forWhom);
+        Message msg = mHandler.obtainMessage(EVENT_EXPIRE_NET_TRANSITION_WAKELOCK);
+        final int lockTimeout = mResources.get().getInteger(
+                R.integer.config_networkTransitionTimeout);
+        mHandler.sendMessageDelayed(msg, lockTimeout);
+    }
+
+    // Called when we gain a new default network to release the network transition wakelock in a
+    // second, to allow a grace period for apps to reconnect over the new network. Pending expiry
+    // message is cancelled.
+    private void scheduleReleaseNetworkTransitionWakelock() {
+        synchronized (this) {
+            if (!mNetTransitionWakeLock.isHeld()) {
+                return; // expiry message released the lock first.
+            }
+        }
+        // Cancel self timeout on wakelock hold.
+        mHandler.removeMessages(EVENT_EXPIRE_NET_TRANSITION_WAKELOCK);
+        Message msg = mHandler.obtainMessage(EVENT_CLEAR_NET_TRANSITION_WAKELOCK);
+        mHandler.sendMessageDelayed(msg, 1000);
+    }
+
+    // Called when either message of ensureNetworkTransitionWakelock or
+    // scheduleReleaseNetworkTransitionWakelock is processed.
+    private void handleReleaseNetworkTransitionWakelock(int eventId) {
+        String event = eventName(eventId);
+        synchronized (this) {
+            if (!mNetTransitionWakeLock.isHeld()) {
+                mWakelockLogs.log(String.format("RELEASE: already released (%s)", event));
+                Log.w(TAG, "expected Net Transition WakeLock to be held");
+                return;
+            }
+            mNetTransitionWakeLock.release();
+            long lockDuration = SystemClock.elapsedRealtime() - mLastWakeLockAcquireTimestamp;
+            mTotalWakelockDurationMs += lockDuration;
+            mMaxWakelockDurationMs = Math.max(mMaxWakelockDurationMs, lockDuration);
+            mTotalWakelockReleases++;
+        }
+        mWakelockLogs.log(String.format("RELEASE (%s)", event));
+    }
+
+    // 100 percent is full good, 0 is full bad.
+    @Override
+    public void reportInetCondition(int networkType, int percentage) {
+        NetworkAgentInfo nai = mLegacyTypeTracker.getNetworkForType(networkType);
+        if (nai == null) return;
+        reportNetworkConnectivity(nai.network, percentage > 50);
+    }
+
+    @Override
+    public void reportNetworkConnectivity(Network network, boolean hasConnectivity) {
+        enforceAccessPermission();
+        enforceInternetPermission();
+        final int uid = mDeps.getCallingUid();
+        final int connectivityInfo = encodeBool(hasConnectivity);
+
+        // Handle ConnectivityDiagnostics event before attempting to revalidate the network. This
+        // forces an ordering of ConnectivityDiagnostics events in the case where hasConnectivity
+        // does not match the known connectivity of the network - this causes NetworkMonitor to
+        // revalidate the network and generate a ConnectivityDiagnostics ConnectivityReport event.
+        final NetworkAgentInfo nai;
+        if (network == null) {
+            nai = getDefaultNetwork();
+        } else {
+            nai = getNetworkAgentInfoForNetwork(network);
+        }
+        if (nai != null) {
+            mConnectivityDiagnosticsHandler.sendMessage(
+                    mConnectivityDiagnosticsHandler.obtainMessage(
+                            ConnectivityDiagnosticsHandler.EVENT_NETWORK_CONNECTIVITY_REPORTED,
+                            connectivityInfo, 0, nai));
+        }
+
+        mHandler.sendMessage(
+                mHandler.obtainMessage(EVENT_REVALIDATE_NETWORK, uid, connectivityInfo, network));
+    }
+
+    private void handleReportNetworkConnectivity(
+            Network network, int uid, boolean hasConnectivity) {
+        final NetworkAgentInfo nai;
+        if (network == null) {
+            nai = getDefaultNetwork();
+        } else {
+            nai = getNetworkAgentInfoForNetwork(network);
+        }
+        if (nai == null || nai.networkInfo.getState() == NetworkInfo.State.DISCONNECTING ||
+            nai.networkInfo.getState() == NetworkInfo.State.DISCONNECTED) {
+            return;
+        }
+        // Revalidate if the app report does not match our current validated state.
+        if (hasConnectivity == nai.lastValidated) {
+            return;
+        }
+        if (DBG) {
+            int netid = nai.network.getNetId();
+            log("reportNetworkConnectivity(" + netid + ", " + hasConnectivity + ") by " + uid);
+        }
+        // Validating a network that has not yet connected could result in a call to
+        // rematchNetworkAndRequests() which is not meant to work on such networks.
+        if (!nai.everConnected) {
+            return;
+        }
+        final NetworkCapabilities nc = getNetworkCapabilitiesInternal(nai);
+        if (isNetworkWithCapabilitiesBlocked(nc, uid, false)) {
+            return;
+        }
+        nai.networkMonitor().forceReevaluation(uid);
+    }
+
+    // TODO: call into netd.
+    private boolean queryUserAccess(int uid, Network network) {
+        final NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+        if (nai == null) return false;
+
+        // Any UID can use its default network.
+        if (nai == getDefaultNetworkForUid(uid)) return true;
+
+        // Privileged apps can use any network.
+        if (mPermissionMonitor.hasRestrictedNetworksPermission(uid)) {
+            return true;
+        }
+
+        // An unprivileged UID can use a VPN iff the VPN applies to it.
+        if (nai.isVPN()) {
+            return nai.networkCapabilities.appliesToUid(uid);
+        }
+
+        // An unprivileged UID can bypass the VPN that applies to it only if it can protect its
+        // sockets, i.e., if it is the owner.
+        final NetworkAgentInfo vpn = getVpnForUid(uid);
+        if (vpn != null && !vpn.networkAgentConfig.allowBypass
+                && uid != vpn.networkCapabilities.getOwnerUid()) {
+            return false;
+        }
+
+        // The UID's permission must be at least sufficient for the network. Since the restricted
+        // permission was already checked above, that just leaves background networks.
+        if (!nai.networkCapabilities.hasCapability(NET_CAPABILITY_FOREGROUND)) {
+            return mPermissionMonitor.hasUseBackgroundNetworksPermission(uid);
+        }
+
+        // Unrestricted network. Anyone gets to use it.
+        return true;
+    }
+
+    /**
+     * Returns information about the proxy a certain network is using. If given a null network, it
+     * it will return the proxy for the bound network for the caller app or the default proxy if
+     * none.
+     *
+     * @param network the network we want to get the proxy information for.
+     * @return Proxy information if a network has a proxy configured, or otherwise null.
+     */
+    @Override
+    public ProxyInfo getProxyForNetwork(Network network) {
+        final ProxyInfo globalProxy = mProxyTracker.getGlobalProxy();
+        if (globalProxy != null) return globalProxy;
+        if (network == null) {
+            // Get the network associated with the calling UID.
+            final Network activeNetwork = getActiveNetworkForUidInternal(mDeps.getCallingUid(),
+                    true);
+            if (activeNetwork == null) {
+                return null;
+            }
+            return getLinkPropertiesProxyInfo(activeNetwork);
+        } else if (mDeps.queryUserAccess(mDeps.getCallingUid(), network, this)) {
+            // Don't call getLinkProperties() as it requires ACCESS_NETWORK_STATE permission, which
+            // caller may not have.
+            return getLinkPropertiesProxyInfo(network);
+        }
+        // No proxy info available if the calling UID does not have network access.
+        return null;
+    }
+
+
+    private ProxyInfo getLinkPropertiesProxyInfo(Network network) {
+        final NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+        if (nai == null) return null;
+        synchronized (nai) {
+            final ProxyInfo linkHttpProxy = nai.linkProperties.getHttpProxy();
+            return linkHttpProxy == null ? null : new ProxyInfo(linkHttpProxy);
+        }
+    }
+
+    @Override
+    public void setGlobalProxy(@Nullable final ProxyInfo proxyProperties) {
+        PermissionUtils.enforceNetworkStackPermission(mContext);
+        mProxyTracker.setGlobalProxy(proxyProperties);
+    }
+
+    @Override
+    @Nullable
+    public ProxyInfo getGlobalProxy() {
+        return mProxyTracker.getGlobalProxy();
+    }
+
+    private void handleApplyDefaultProxy(ProxyInfo proxy) {
+        if (proxy != null && TextUtils.isEmpty(proxy.getHost())
+                && Uri.EMPTY.equals(proxy.getPacFileUrl())) {
+            proxy = null;
+        }
+        mProxyTracker.setDefaultProxy(proxy);
+    }
+
+    // If the proxy has changed from oldLp to newLp, resend proxy broadcast. This method gets called
+    // when any network changes proxy.
+    // TODO: Remove usage of broadcast extras as they are deprecated and not applicable in a
+    // multi-network world where an app might be bound to a non-default network.
+    private void updateProxy(LinkProperties newLp, LinkProperties oldLp) {
+        ProxyInfo newProxyInfo = newLp == null ? null : newLp.getHttpProxy();
+        ProxyInfo oldProxyInfo = oldLp == null ? null : oldLp.getHttpProxy();
+
+        if (!ProxyTracker.proxyInfoEqual(newProxyInfo, oldProxyInfo)) {
+            mProxyTracker.sendProxyBroadcast();
+        }
+    }
+
+    private static class SettingsObserver extends ContentObserver {
+        final private HashMap<Uri, Integer> mUriEventMap;
+        final private Context mContext;
+        final private Handler mHandler;
+
+        SettingsObserver(Context context, Handler handler) {
+            super(null);
+            mUriEventMap = new HashMap<>();
+            mContext = context;
+            mHandler = handler;
+        }
+
+        void observe(Uri uri, int what) {
+            mUriEventMap.put(uri, what);
+            final ContentResolver resolver = mContext.getContentResolver();
+            resolver.registerContentObserver(uri, false, this);
+        }
+
+        @Override
+        public void onChange(boolean selfChange) {
+            Log.wtf(TAG, "Should never be reached.");
+        }
+
+        @Override
+        public void onChange(boolean selfChange, Uri uri) {
+            final Integer what = mUriEventMap.get(uri);
+            if (what != null) {
+                mHandler.obtainMessage(what).sendToTarget();
+            } else {
+                loge("No matching event to send for URI=" + uri);
+            }
+        }
+    }
+
+    private static void log(String s) {
+        Log.d(TAG, s);
+    }
+
+    private static void logw(String s) {
+        Log.w(TAG, s);
+    }
+
+    private static void logwtf(String s) {
+        Log.wtf(TAG, s);
+    }
+
+    private static void logwtf(String s, Throwable t) {
+        Log.wtf(TAG, s, t);
+    }
+
+    private static void loge(String s) {
+        Log.e(TAG, s);
+    }
+
+    private static void loge(String s, Throwable t) {
+        Log.e(TAG, s, t);
+    }
+
+    /**
+     * Return the information of all ongoing VPNs.
+     *
+     * <p>This method is used to update NetworkStatsService.
+     *
+     * <p>Must be called on the handler thread.
+     */
+    private UnderlyingNetworkInfo[] getAllVpnInfo() {
+        ensureRunningOnConnectivityServiceThread();
+        if (mLockdownEnabled) {
+            return new UnderlyingNetworkInfo[0];
+        }
+        List<UnderlyingNetworkInfo> infoList = new ArrayList<>();
+        for (NetworkAgentInfo nai : mNetworkAgentInfos) {
+            UnderlyingNetworkInfo info = createVpnInfo(nai);
+            if (info != null) {
+                infoList.add(info);
+            }
+        }
+        return infoList.toArray(new UnderlyingNetworkInfo[infoList.size()]);
+    }
+
+    /**
+     * @return VPN information for accounting, or null if we can't retrieve all required
+     *         information, e.g underlying ifaces.
+     */
+    private UnderlyingNetworkInfo createVpnInfo(NetworkAgentInfo nai) {
+        if (!nai.isVPN()) return null;
+
+        Network[] underlyingNetworks = nai.declaredUnderlyingNetworks;
+        // see VpnService.setUnderlyingNetworks()'s javadoc about how to interpret
+        // the underlyingNetworks list.
+        if (underlyingNetworks == null) {
+            final NetworkAgentInfo defaultNai = getDefaultNetworkForUid(
+                    nai.networkCapabilities.getOwnerUid());
+            if (defaultNai != null) {
+                underlyingNetworks = new Network[] { defaultNai.network };
+            }
+        }
+
+        if (CollectionUtils.isEmpty(underlyingNetworks)) return null;
+
+        List<String> interfaces = new ArrayList<>();
+        for (Network network : underlyingNetworks) {
+            NetworkAgentInfo underlyingNai = getNetworkAgentInfoForNetwork(network);
+            if (underlyingNai == null) continue;
+            LinkProperties lp = underlyingNai.linkProperties;
+            for (String iface : lp.getAllInterfaceNames()) {
+                if (!TextUtils.isEmpty(iface)) {
+                    interfaces.add(iface);
+                }
+            }
+        }
+
+        if (interfaces.isEmpty()) return null;
+
+        // Must be non-null or NetworkStatsService will crash.
+        // Cannot happen in production code because Vpn only registers the NetworkAgent after the
+        // tun or ipsec interface is created.
+        // TODO: Remove this check.
+        if (nai.linkProperties.getInterfaceName() == null) return null;
+
+        return new UnderlyingNetworkInfo(nai.networkCapabilities.getOwnerUid(),
+                nai.linkProperties.getInterfaceName(), interfaces);
+    }
+
+    // TODO This needs to be the default network that applies to the NAI.
+    private Network[] underlyingNetworksOrDefault(final int ownerUid,
+            Network[] underlyingNetworks) {
+        final Network defaultNetwork = getNetwork(getDefaultNetworkForUid(ownerUid));
+        if (underlyingNetworks == null && defaultNetwork != null) {
+            // null underlying networks means to track the default.
+            underlyingNetworks = new Network[] { defaultNetwork };
+        }
+        return underlyingNetworks;
+    }
+
+    // Returns true iff |network| is an underlying network of |nai|.
+    private boolean hasUnderlyingNetwork(NetworkAgentInfo nai, Network network) {
+        // TODO: support more than one level of underlying networks, either via a fixed-depth search
+        // (e.g., 2 levels of underlying networks), or via loop detection, or....
+        if (!nai.supportsUnderlyingNetworks()) return false;
+        final Network[] underlying = underlyingNetworksOrDefault(
+                nai.networkCapabilities.getOwnerUid(), nai.declaredUnderlyingNetworks);
+        return CollectionUtils.contains(underlying, network);
+    }
+
+    /**
+     * Recompute the capabilities for any networks that had a specific network as underlying.
+     *
+     * When underlying networks change, such networks may have to update capabilities to reflect
+     * things like the metered bit, their transports, and so on. The capabilities are calculated
+     * immediately. This method runs on the ConnectivityService thread.
+     */
+    private void propagateUnderlyingNetworkCapabilities(Network updatedNetwork) {
+        ensureRunningOnConnectivityServiceThread();
+        for (NetworkAgentInfo nai : mNetworkAgentInfos) {
+            if (updatedNetwork == null || hasUnderlyingNetwork(nai, updatedNetwork)) {
+                updateCapabilitiesForNetwork(nai);
+            }
+        }
+    }
+
+    private boolean isUidBlockedByVpn(int uid, List<UidRange> blockedUidRanges) {
+        // Determine whether this UID is blocked because of always-on VPN lockdown. If a VPN applies
+        // to the UID, then the UID is not blocked because always-on VPN lockdown applies only when
+        // a VPN is not up.
+        final NetworkAgentInfo vpnNai = getVpnForUid(uid);
+        if (vpnNai != null && !vpnNai.networkAgentConfig.allowBypass) return false;
+        for (UidRange range : blockedUidRanges) {
+            if (range.contains(uid)) return true;
+        }
+        return false;
+    }
+
+    @Override
+    public void setRequireVpnForUids(boolean requireVpn, UidRange[] ranges) {
+        enforceNetworkStackOrSettingsPermission();
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_SET_REQUIRE_VPN_FOR_UIDS,
+                encodeBool(requireVpn), 0 /* arg2 */, ranges));
+    }
+
+    private void handleSetRequireVpnForUids(boolean requireVpn, UidRange[] ranges) {
+        if (DBG) {
+            Log.d(TAG, "Setting VPN " + (requireVpn ? "" : "not ") + "required for UIDs: "
+                    + Arrays.toString(ranges));
+        }
+        // Cannot use a Set since the list of UID ranges might contain duplicates.
+        final List<UidRange> newVpnBlockedUidRanges = new ArrayList(mVpnBlockedUidRanges);
+        for (int i = 0; i < ranges.length; i++) {
+            if (requireVpn) {
+                newVpnBlockedUidRanges.add(ranges[i]);
+            } else {
+                newVpnBlockedUidRanges.remove(ranges[i]);
+            }
+        }
+
+        try {
+            mNetd.networkRejectNonSecureVpn(requireVpn, toUidRangeStableParcels(ranges));
+        } catch (RemoteException | ServiceSpecificException e) {
+            Log.e(TAG, "setRequireVpnForUids(" + requireVpn + ", "
+                    + Arrays.toString(ranges) + "): netd command failed: " + e);
+        }
+
+        for (final NetworkAgentInfo nai : mNetworkAgentInfos) {
+            final boolean curMetered = nai.networkCapabilities.isMetered();
+            maybeNotifyNetworkBlocked(nai, curMetered, curMetered,
+                    mVpnBlockedUidRanges, newVpnBlockedUidRanges);
+        }
+
+        mVpnBlockedUidRanges = newVpnBlockedUidRanges;
+    }
+
+    @Override
+    public void setLegacyLockdownVpnEnabled(boolean enabled) {
+        enforceNetworkStackOrSettingsPermission();
+        mHandler.post(() -> mLockdownEnabled = enabled);
+    }
+
+    private boolean isLegacyLockdownNai(NetworkAgentInfo nai) {
+        return mLockdownEnabled
+                && getVpnType(nai) == VpnManager.TYPE_VPN_LEGACY
+                && nai.networkCapabilities.appliesToUid(Process.FIRST_APPLICATION_UID);
+    }
+
+    private NetworkAgentInfo getLegacyLockdownNai() {
+        if (!mLockdownEnabled) {
+            return null;
+        }
+        // The legacy lockdown VPN always only applies to userId 0.
+        final NetworkAgentInfo nai = getVpnForUid(Process.FIRST_APPLICATION_UID);
+        if (nai == null || !isLegacyLockdownNai(nai)) return null;
+
+        // The legacy lockdown VPN must always have exactly one underlying network.
+        // This code may run on any thread and declaredUnderlyingNetworks may change, so store it in
+        // a local variable. There is no need to make a copy because its contents cannot change.
+        final Network[] underlying = nai.declaredUnderlyingNetworks;
+        if (underlying == null ||  underlying.length != 1) {
+            return null;
+        }
+
+        // The legacy lockdown VPN always uses the default network.
+        // If the VPN's underlying network is no longer the current default network, it means that
+        // the default network has just switched, and the VPN is about to disconnect.
+        // Report that the VPN is not connected, so the state of NetworkInfo objects overwritten
+        // by filterForLegacyLockdown will be set to CONNECTING and not CONNECTED.
+        final NetworkAgentInfo defaultNetwork = getDefaultNetwork();
+        if (defaultNetwork == null || !defaultNetwork.network.equals(underlying[0])) {
+            return null;
+        }
+
+        return nai;
+    };
+
+    // TODO: move all callers to filterForLegacyLockdown and delete this method.
+    // This likely requires making sendLegacyNetworkBroadcast take a NetworkInfo object instead of
+    // just a DetailedState object.
+    private DetailedState getLegacyLockdownState(DetailedState origState) {
+        if (origState != DetailedState.CONNECTED) {
+            return origState;
+        }
+        return (mLockdownEnabled && getLegacyLockdownNai() == null)
+                ? DetailedState.CONNECTING
+                : DetailedState.CONNECTED;
+    }
+
+    private void filterForLegacyLockdown(NetworkInfo ni) {
+        if (!mLockdownEnabled || !ni.isConnected()) return;
+        // The legacy lockdown VPN replaces the state of every network in CONNECTED state with the
+        // state of its VPN. This is to ensure that when an underlying network connects, apps will
+        // not see a CONNECTIVITY_ACTION broadcast for a network in state CONNECTED until the VPN
+        // comes up, at which point there is a new CONNECTIVITY_ACTION broadcast for the underlying
+        // network, this time with a state of CONNECTED.
+        //
+        // Now that the legacy lockdown code lives in ConnectivityService, and no longer has access
+        // to the internal state of the Vpn object, always replace the state with CONNECTING. This
+        // is not too far off the truth, since an always-on VPN, when not connected, is always
+        // trying to reconnect.
+        if (getLegacyLockdownNai() == null) {
+            ni.setDetailedState(DetailedState.CONNECTING, "", null);
+        }
+    }
+
+    @Override
+    public void setProvisioningNotificationVisible(boolean visible, int networkType,
+            String action) {
+        enforceSettingsPermission();
+        if (!ConnectivityManager.isNetworkTypeValid(networkType)) {
+            return;
+        }
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            // Concatenate the range of types onto the range of NetIDs.
+            int id = NetIdManager.MAX_NET_ID + 1 + (networkType - ConnectivityManager.TYPE_NONE);
+            mNotifier.setProvNotificationVisible(visible, id, action);
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+    }
+
+    @Override
+    public void setAirplaneMode(boolean enable) {
+        enforceAirplaneModePermission();
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            final ContentResolver cr = mContext.getContentResolver();
+            Settings.Global.putInt(cr, Settings.Global.AIRPLANE_MODE_ON, encodeBool(enable));
+            Intent intent = new Intent(Intent.ACTION_AIRPLANE_MODE_CHANGED);
+            intent.putExtra("state", enable);
+            mContext.sendBroadcastAsUser(intent, UserHandle.ALL);
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+    }
+
+    private void onUserAdded(@NonNull final UserHandle user) {
+        mPermissionMonitor.onUserAdded(user);
+        if (mOemNetworkPreferences.getNetworkPreferences().size() > 0) {
+            handleSetOemNetworkPreference(mOemNetworkPreferences, null);
+        }
+    }
+
+    private void onUserRemoved(@NonNull final UserHandle user) {
+        mPermissionMonitor.onUserRemoved(user);
+        // If there was a network preference for this user, remove it.
+        handleSetProfileNetworkPreference(new ProfileNetworkPreferences.Preference(user, null),
+                null /* listener */);
+        if (mOemNetworkPreferences.getNetworkPreferences().size() > 0) {
+            handleSetOemNetworkPreference(mOemNetworkPreferences, null);
+        }
+    }
+
+    private void onPackageChanged(@NonNull final String packageName) {
+        // This is necessary in case a package is added or removed, but also when it's replaced to
+        // run as a new UID by its manifest rules. Also, if a separate package shares the same UID
+        // as one in the preferences, then it should follow the same routing as that other package,
+        // which means updating the rules is never to be needed in this case (whether it joins or
+        // leaves a UID with a preference).
+        if (isMappedInOemNetworkPreference(packageName)) {
+            handleSetOemNetworkPreference(mOemNetworkPreferences, null);
+        }
+    }
+
+    private final BroadcastReceiver mUserIntentReceiver = new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            ensureRunningOnConnectivityServiceThread();
+            final String action = intent.getAction();
+            final UserHandle user = intent.getParcelableExtra(Intent.EXTRA_USER);
+
+            // User should be filled for below intents, check the existence.
+            if (user == null) {
+                Log.wtf(TAG, intent.getAction() + " broadcast without EXTRA_USER");
+                return;
+            }
+
+            if (Intent.ACTION_USER_ADDED.equals(action)) {
+                onUserAdded(user);
+            } else if (Intent.ACTION_USER_REMOVED.equals(action)) {
+                onUserRemoved(user);
+            }  else {
+                Log.wtf(TAG, "received unexpected intent: " + action);
+            }
+        }
+    };
+
+    private final BroadcastReceiver mPackageIntentReceiver = new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            ensureRunningOnConnectivityServiceThread();
+            switch (intent.getAction()) {
+                case Intent.ACTION_PACKAGE_ADDED:
+                case Intent.ACTION_PACKAGE_REMOVED:
+                case Intent.ACTION_PACKAGE_REPLACED:
+                    onPackageChanged(intent.getData().getSchemeSpecificPart());
+                    break;
+                default:
+                    Log.wtf(TAG, "received unexpected intent: " + intent.getAction());
+            }
+        }
+    };
+
+    private final HashMap<Messenger, NetworkProviderInfo> mNetworkProviderInfos = new HashMap<>();
+    private final HashMap<NetworkRequest, NetworkRequestInfo> mNetworkRequests = new HashMap<>();
+
+    private static class NetworkProviderInfo {
+        public final String name;
+        public final Messenger messenger;
+        private final IBinder.DeathRecipient mDeathRecipient;
+        public final int providerId;
+
+        NetworkProviderInfo(String name, Messenger messenger, int providerId,
+                @NonNull IBinder.DeathRecipient deathRecipient) {
+            this.name = name;
+            this.messenger = messenger;
+            this.providerId = providerId;
+            mDeathRecipient = deathRecipient;
+
+            if (mDeathRecipient == null) {
+                throw new AssertionError("Must pass a deathRecipient");
+            }
+        }
+
+        void connect(Context context, Handler handler) {
+            try {
+                messenger.getBinder().linkToDeath(mDeathRecipient, 0);
+            } catch (RemoteException e) {
+                mDeathRecipient.binderDied();
+            }
+        }
+    }
+
+    private void ensureAllNetworkRequestsHaveType(List<NetworkRequest> requests) {
+        for (int i = 0; i < requests.size(); i++) {
+            ensureNetworkRequestHasType(requests.get(i));
+        }
+    }
+
+    private void ensureNetworkRequestHasType(NetworkRequest request) {
+        if (request.type == NetworkRequest.Type.NONE) {
+            throw new IllegalArgumentException(
+                    "All NetworkRequests in ConnectivityService must have a type");
+        }
+    }
+
+    /**
+     * Tracks info about the requester.
+     * Also used to notice when the calling process dies so as to self-expire
+     */
+    @VisibleForTesting
+    protected class NetworkRequestInfo implements IBinder.DeathRecipient {
+        // The requests to be satisfied in priority order. Non-multilayer requests will only have a
+        // single NetworkRequest in mRequests.
+        final List<NetworkRequest> mRequests;
+
+        // mSatisfier and mActiveRequest rely on one another therefore set them together.
+        void setSatisfier(
+                @Nullable final NetworkAgentInfo satisfier,
+                @Nullable final NetworkRequest activeRequest) {
+            mSatisfier = satisfier;
+            mActiveRequest = activeRequest;
+        }
+
+        // The network currently satisfying this NRI. Only one request in an NRI can have a
+        // satisfier. For non-multilayer requests, only non-listen requests can have a satisfier.
+        @Nullable
+        private NetworkAgentInfo mSatisfier;
+        NetworkAgentInfo getSatisfier() {
+            return mSatisfier;
+        }
+
+        // The request in mRequests assigned to a network agent. This is null if none of the
+        // requests in mRequests can be satisfied. This member has the constraint of only being
+        // accessible on the handler thread.
+        @Nullable
+        private NetworkRequest mActiveRequest;
+        NetworkRequest getActiveRequest() {
+            return mActiveRequest;
+        }
+
+        final PendingIntent mPendingIntent;
+        boolean mPendingIntentSent;
+        @Nullable
+        final Messenger mMessenger;
+
+        // Information about the caller that caused this object to be created.
+        @Nullable
+        private final IBinder mBinder;
+        final int mPid;
+        final int mUid;
+        final @NetworkCallback.Flag int mCallbackFlags;
+        @Nullable
+        final String mCallingAttributionTag;
+
+        // Counter keeping track of this NRI.
+        final PerUidCounter mPerUidCounter;
+
+        // Effective UID of this request. This is different from mUid when a privileged process
+        // files a request on behalf of another UID. This UID is used to determine blocked status,
+        // UID matching, and so on. mUid above is used for permission checks and to enforce the
+        // maximum limit of registered callbacks per UID.
+        final int mAsUid;
+
+        // In order to preserve the mapping of NetworkRequest-to-callback when apps register
+        // callbacks using a returned NetworkRequest, the original NetworkRequest needs to be
+        // maintained for keying off of. This is only a concern when the original nri
+        // mNetworkRequests changes which happens currently for apps that register callbacks to
+        // track the default network. In those cases, the nri is updated to have mNetworkRequests
+        // that match the per-app default nri that currently tracks the calling app's uid so that
+        // callbacks are fired at the appropriate time. When the callbacks fire,
+        // mNetworkRequestForCallback will be used so as to preserve the caller's mapping. When
+        // callbacks are updated to key off of an nri vs NetworkRequest, this stops being an issue.
+        // TODO b/177608132: make sure callbacks are indexed by NRIs and not NetworkRequest objects.
+        @NonNull
+        private final NetworkRequest mNetworkRequestForCallback;
+        NetworkRequest getNetworkRequestForCallback() {
+            return mNetworkRequestForCallback;
+        }
+
+        /**
+         * Get the list of UIDs this nri applies to.
+         */
+        @NonNull
+        private Set<UidRange> getUids() {
+            // networkCapabilities.getUids() returns a defensive copy.
+            // multilayer requests will all have the same uids so return the first one.
+            final Set<UidRange> uids = mRequests.get(0).networkCapabilities.getUidRanges();
+            return (null == uids) ? new ArraySet<>() : uids;
+        }
+
+        NetworkRequestInfo(int asUid, @NonNull final NetworkRequest r,
+                @Nullable final PendingIntent pi, @Nullable String callingAttributionTag) {
+            this(asUid, Collections.singletonList(r), r, pi, callingAttributionTag);
+        }
+
+        NetworkRequestInfo(int asUid, @NonNull final List<NetworkRequest> r,
+                @NonNull final NetworkRequest requestForCallback, @Nullable final PendingIntent pi,
+                @Nullable String callingAttributionTag) {
+            ensureAllNetworkRequestsHaveType(r);
+            mRequests = initializeRequests(r);
+            mNetworkRequestForCallback = requestForCallback;
+            mPendingIntent = pi;
+            mMessenger = null;
+            mBinder = null;
+            mPid = getCallingPid();
+            mUid = mDeps.getCallingUid();
+            mAsUid = asUid;
+            mPerUidCounter = getRequestCounter(this);
+            mPerUidCounter.incrementCountOrThrow(mUid);
+            /**
+             * Location sensitive data not included in pending intent. Only included in
+             * {@link NetworkCallback}.
+             */
+            mCallbackFlags = NetworkCallback.FLAG_NONE;
+            mCallingAttributionTag = callingAttributionTag;
+        }
+
+        NetworkRequestInfo(int asUid, @NonNull final NetworkRequest r, @Nullable final Messenger m,
+                @Nullable final IBinder binder,
+                @NetworkCallback.Flag int callbackFlags,
+                @Nullable String callingAttributionTag) {
+            this(asUid, Collections.singletonList(r), r, m, binder, callbackFlags,
+                    callingAttributionTag);
+        }
+
+        NetworkRequestInfo(int asUid, @NonNull final List<NetworkRequest> r,
+                @NonNull final NetworkRequest requestForCallback, @Nullable final Messenger m,
+                @Nullable final IBinder binder,
+                @NetworkCallback.Flag int callbackFlags,
+                @Nullable String callingAttributionTag) {
+            super();
+            ensureAllNetworkRequestsHaveType(r);
+            mRequests = initializeRequests(r);
+            mNetworkRequestForCallback = requestForCallback;
+            mMessenger = m;
+            mBinder = binder;
+            mPid = getCallingPid();
+            mUid = mDeps.getCallingUid();
+            mAsUid = asUid;
+            mPendingIntent = null;
+            mPerUidCounter = getRequestCounter(this);
+            mPerUidCounter.incrementCountOrThrow(mUid);
+            mCallbackFlags = callbackFlags;
+            mCallingAttributionTag = callingAttributionTag;
+            linkDeathRecipient();
+        }
+
+        NetworkRequestInfo(@NonNull final NetworkRequestInfo nri,
+                @NonNull final List<NetworkRequest> r) {
+            super();
+            ensureAllNetworkRequestsHaveType(r);
+            mRequests = initializeRequests(r);
+            mNetworkRequestForCallback = nri.getNetworkRequestForCallback();
+            final NetworkAgentInfo satisfier = nri.getSatisfier();
+            if (null != satisfier) {
+                // If the old NRI was satisfied by an NAI, then it may have had an active request.
+                // The active request is necessary to figure out what callbacks to send, in
+                // particular then a network updates its capabilities.
+                // As this code creates a new NRI with a new set of requests, figure out which of
+                // the list of requests should be the active request. It is always the first
+                // request of the list that can be satisfied by the satisfier since the order of
+                // requests is a priority order.
+                // Note even in the presence of a satisfier there may not be an active request,
+                // when the satisfier is the no-service network.
+                NetworkRequest activeRequest = null;
+                for (final NetworkRequest candidate : r) {
+                    if (candidate.canBeSatisfiedBy(satisfier.networkCapabilities)) {
+                        activeRequest = candidate;
+                        break;
+                    }
+                }
+                setSatisfier(satisfier, activeRequest);
+            }
+            mMessenger = nri.mMessenger;
+            mBinder = nri.mBinder;
+            mPid = nri.mPid;
+            mUid = nri.mUid;
+            mAsUid = nri.mAsUid;
+            mPendingIntent = nri.mPendingIntent;
+            mPerUidCounter = getRequestCounter(this);
+            mPerUidCounter.incrementCountOrThrow(mUid);
+            mCallbackFlags = nri.mCallbackFlags;
+            mCallingAttributionTag = nri.mCallingAttributionTag;
+            linkDeathRecipient();
+        }
+
+        NetworkRequestInfo(int asUid, @NonNull final NetworkRequest r) {
+            this(asUid, Collections.singletonList(r));
+        }
+
+        NetworkRequestInfo(int asUid, @NonNull final List<NetworkRequest> r) {
+            this(asUid, r, r.get(0), null /* pi */, null /* callingAttributionTag */);
+        }
+
+        // True if this NRI is being satisfied. It also accounts for if the nri has its satisifer
+        // set to the mNoServiceNetwork in which case mActiveRequest will be null thus returning
+        // false.
+        boolean isBeingSatisfied() {
+            return (null != mSatisfier && null != mActiveRequest);
+        }
+
+        boolean isMultilayerRequest() {
+            return mRequests.size() > 1;
+        }
+
+        private List<NetworkRequest> initializeRequests(List<NetworkRequest> r) {
+            // Creating a defensive copy to prevent the sender from modifying the list being
+            // reflected in the return value of this method.
+            final List<NetworkRequest> tempRequests = new ArrayList<>(r);
+            return Collections.unmodifiableList(tempRequests);
+        }
+
+        void decrementRequestCount() {
+            mPerUidCounter.decrementCount(mUid);
+        }
+
+        void linkDeathRecipient() {
+            if (null != mBinder) {
+                try {
+                    mBinder.linkToDeath(this, 0);
+                } catch (RemoteException e) {
+                    binderDied();
+                }
+            }
+        }
+
+        void unlinkDeathRecipient() {
+            if (null != mBinder) {
+                mBinder.unlinkToDeath(this, 0);
+            }
+        }
+
+        @Override
+        public void binderDied() {
+            log("ConnectivityService NetworkRequestInfo binderDied(" +
+                    mRequests + ", " + mBinder + ")");
+            releaseNetworkRequests(mRequests);
+        }
+
+        @Override
+        public String toString() {
+            final String asUidString = (mAsUid == mUid) ? "" : " asUid: " + mAsUid;
+            return "uid/pid:" + mUid + "/" + mPid + asUidString + " activeRequest: "
+                    + (mActiveRequest == null ? null : mActiveRequest.requestId)
+                    + " callbackRequest: "
+                    + mNetworkRequestForCallback.requestId
+                    + " " + mRequests
+                    + (mPendingIntent == null ? "" : " to trigger " + mPendingIntent)
+                    + " callback flags: " + mCallbackFlags;
+        }
+    }
+
+    private void ensureRequestableCapabilities(NetworkCapabilities networkCapabilities) {
+        final String badCapability = networkCapabilities.describeFirstNonRequestableCapability();
+        if (badCapability != null) {
+            throw new IllegalArgumentException("Cannot request network with " + badCapability);
+        }
+    }
+
+    // This checks that the passed capabilities either do not request a
+    // specific SSID/SignalStrength, or the calling app has permission to do so.
+    private void ensureSufficientPermissionsForRequest(NetworkCapabilities nc,
+            int callerPid, int callerUid, String callerPackageName) {
+        if (null != nc.getSsid() && !checkSettingsPermission(callerPid, callerUid)) {
+            throw new SecurityException("Insufficient permissions to request a specific SSID");
+        }
+
+        if (nc.hasSignalStrength()
+                && !checkNetworkSignalStrengthWakeupPermission(callerPid, callerUid)) {
+            throw new SecurityException(
+                    "Insufficient permissions to request a specific signal strength");
+        }
+        mAppOpsManager.checkPackage(callerUid, callerPackageName);
+
+        if (!nc.getSubscriptionIds().isEmpty()) {
+            enforceNetworkFactoryPermission();
+        }
+    }
+
+    private int[] getSignalStrengthThresholds(@NonNull final NetworkAgentInfo nai) {
+        final SortedSet<Integer> thresholds = new TreeSet<>();
+        synchronized (nai) {
+            // mNetworkRequests may contain the same value multiple times in case of
+            // multilayer requests. It won't matter in this case because the thresholds
+            // will then be the same and be deduplicated as they enter the `thresholds` set.
+            // TODO : have mNetworkRequests be a Set<NetworkRequestInfo> or the like.
+            for (final NetworkRequestInfo nri : mNetworkRequests.values()) {
+                for (final NetworkRequest req : nri.mRequests) {
+                    if (req.networkCapabilities.hasSignalStrength()
+                            && nai.satisfiesImmutableCapabilitiesOf(req)) {
+                        thresholds.add(req.networkCapabilities.getSignalStrength());
+                    }
+                }
+            }
+        }
+        return CollectionUtils.toIntArray(new ArrayList<>(thresholds));
+    }
+
+    private void updateSignalStrengthThresholds(
+            NetworkAgentInfo nai, String reason, NetworkRequest request) {
+        final int[] thresholdsArray = getSignalStrengthThresholds(nai);
+
+        if (VDBG || (DBG && !"CONNECT".equals(reason))) {
+            String detail;
+            if (request != null && request.networkCapabilities.hasSignalStrength()) {
+                detail = reason + " " + request.networkCapabilities.getSignalStrength();
+            } else {
+                detail = reason;
+            }
+            log(String.format("updateSignalStrengthThresholds: %s, sending %s to %s",
+                    detail, Arrays.toString(thresholdsArray), nai.toShortString()));
+        }
+
+        nai.onSignalStrengthThresholdsUpdated(thresholdsArray);
+    }
+
+    private void ensureValidNetworkSpecifier(NetworkCapabilities nc) {
+        if (nc == null) {
+            return;
+        }
+        NetworkSpecifier ns = nc.getNetworkSpecifier();
+        if (ns == null) {
+            return;
+        }
+        if (ns instanceof MatchAllNetworkSpecifier) {
+            throw new IllegalArgumentException("A MatchAllNetworkSpecifier is not permitted");
+        }
+    }
+
+    private void ensureValid(NetworkCapabilities nc) {
+        ensureValidNetworkSpecifier(nc);
+        if (nc.isPrivateDnsBroken()) {
+            throw new IllegalArgumentException("Can't request broken private DNS");
+        }
+    }
+
+    private boolean isTargetSdkAtleast(int version, int callingUid,
+            @NonNull String callingPackageName) {
+        final UserHandle user = UserHandle.getUserHandleForUid(callingUid);
+        final PackageManager pm =
+                mContext.createContextAsUser(user, 0 /* flags */).getPackageManager();
+        try {
+            final int callingVersion = pm.getTargetSdkVersion(callingPackageName);
+            if (callingVersion < version) return false;
+        } catch (PackageManager.NameNotFoundException e) { }
+        return true;
+    }
+
+    @Override
+    public NetworkRequest requestNetwork(int asUid, NetworkCapabilities networkCapabilities,
+            int reqTypeInt, Messenger messenger, int timeoutMs, IBinder binder,
+            int legacyType, int callbackFlags, @NonNull String callingPackageName,
+            @Nullable String callingAttributionTag) {
+        if (legacyType != TYPE_NONE && !checkNetworkStackPermission()) {
+            if (isTargetSdkAtleast(Build.VERSION_CODES.M, mDeps.getCallingUid(),
+                    callingPackageName)) {
+                throw new SecurityException("Insufficient permissions to specify legacy type");
+            }
+        }
+        final NetworkCapabilities defaultNc = mDefaultRequest.mRequests.get(0).networkCapabilities;
+        final int callingUid = mDeps.getCallingUid();
+        // Privileged callers can track the default network of another UID by passing in a UID.
+        if (asUid != Process.INVALID_UID) {
+            enforceSettingsPermission();
+        } else {
+            asUid = callingUid;
+        }
+        final NetworkRequest.Type reqType;
+        try {
+            reqType = NetworkRequest.Type.values()[reqTypeInt];
+        } catch (ArrayIndexOutOfBoundsException e) {
+            throw new IllegalArgumentException("Unsupported request type " + reqTypeInt);
+        }
+        switch (reqType) {
+            case TRACK_DEFAULT:
+                // If the request type is TRACK_DEFAULT, the passed {@code networkCapabilities}
+                // is unused and will be replaced by ones appropriate for the UID (usually, the
+                // calling app). This allows callers to keep track of the default network.
+                networkCapabilities = copyDefaultNetworkCapabilitiesForUid(
+                        defaultNc, asUid, callingUid, callingPackageName);
+                enforceAccessPermission();
+                break;
+            case TRACK_SYSTEM_DEFAULT:
+                enforceSettingsPermission();
+                networkCapabilities = new NetworkCapabilities(defaultNc);
+                break;
+            case BACKGROUND_REQUEST:
+                enforceNetworkStackOrSettingsPermission();
+                // Fall-through since other checks are the same with normal requests.
+            case REQUEST:
+                networkCapabilities = new NetworkCapabilities(networkCapabilities);
+                enforceNetworkRequestPermissions(networkCapabilities, callingPackageName,
+                        callingAttributionTag);
+                // TODO: this is incorrect. We mark the request as metered or not depending on
+                //  the state of the app when the request is filed, but we never change the
+                //  request if the app changes network state. http://b/29964605
+                enforceMeteredApnPolicy(networkCapabilities);
+                break;
+            case LISTEN_FOR_BEST:
+                enforceAccessPermission();
+                networkCapabilities = new NetworkCapabilities(networkCapabilities);
+                break;
+            default:
+                throw new IllegalArgumentException("Unsupported request type " + reqType);
+        }
+        ensureRequestableCapabilities(networkCapabilities);
+        ensureSufficientPermissionsForRequest(networkCapabilities,
+                Binder.getCallingPid(), callingUid, callingPackageName);
+
+        // Enforce FOREGROUND if the caller does not have permission to use background network.
+        if (reqType == LISTEN_FOR_BEST) {
+            restrictBackgroundRequestForCaller(networkCapabilities);
+        }
+
+        // Set the UID range for this request to the single UID of the requester, unless the
+        // requester has the permission to specify other UIDs.
+        // This will overwrite any allowed UIDs in the requested capabilities. Though there
+        // are no visible methods to set the UIDs, an app could use reflection to try and get
+        // networks for other apps so it's essential that the UIDs are overwritten.
+        // Also set the requester UID and package name in the request.
+        restrictRequestUidsForCallerAndSetRequestorInfo(networkCapabilities,
+                callingUid, callingPackageName);
+
+        if (timeoutMs < 0) {
+            throw new IllegalArgumentException("Bad timeout specified");
+        }
+        ensureValid(networkCapabilities);
+
+        final NetworkRequest networkRequest = new NetworkRequest(networkCapabilities, legacyType,
+                nextNetworkRequestId(), reqType);
+        final NetworkRequestInfo nri = getNriToRegister(
+                asUid, networkRequest, messenger, binder, callbackFlags,
+                callingAttributionTag);
+        if (DBG) log("requestNetwork for " + nri);
+
+        // For TRACK_SYSTEM_DEFAULT callbacks, the capabilities have been modified since they were
+        // copied from the default request above. (This is necessary to ensure, for example, that
+        // the callback does not leak sensitive information to unprivileged apps.) Check that the
+        // changes don't alter request matching.
+        if (reqType == NetworkRequest.Type.TRACK_SYSTEM_DEFAULT &&
+                (!networkCapabilities.equalRequestableCapabilities(defaultNc))) {
+            throw new IllegalStateException(
+                    "TRACK_SYSTEM_DEFAULT capabilities don't match default request: "
+                    + networkCapabilities + " vs. " + defaultNc);
+        }
+
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_REGISTER_NETWORK_REQUEST, nri));
+        if (timeoutMs > 0) {
+            mHandler.sendMessageDelayed(mHandler.obtainMessage(EVENT_TIMEOUT_NETWORK_REQUEST,
+                    nri), timeoutMs);
+        }
+        return networkRequest;
+    }
+
+    /**
+     * Return the nri to be used when registering a network request. Specifically, this is used with
+     * requests registered to track the default request. If there is currently a per-app default
+     * tracking the app requestor, then we need to create a version of this nri that mirrors that of
+     * the tracking per-app default so that callbacks are sent to the app requestor appropriately.
+     * @param asUid the uid on behalf of which to file the request. Different from requestorUid
+     *              when a privileged caller is tracking the default network for another uid.
+     * @param nr the network request for the nri.
+     * @param msgr the messenger for the nri.
+     * @param binder the binder for the nri.
+     * @param callingAttributionTag the calling attribution tag for the nri.
+     * @return the nri to register.
+     */
+    private NetworkRequestInfo getNriToRegister(final int asUid, @NonNull final NetworkRequest nr,
+            @Nullable final Messenger msgr, @Nullable final IBinder binder,
+            @NetworkCallback.Flag int callbackFlags,
+            @Nullable String callingAttributionTag) {
+        final List<NetworkRequest> requests;
+        if (NetworkRequest.Type.TRACK_DEFAULT == nr.type) {
+            requests = copyDefaultNetworkRequestsForUid(
+                    asUid, nr.getRequestorUid(), nr.getRequestorPackageName());
+        } else {
+            requests = Collections.singletonList(nr);
+        }
+        return new NetworkRequestInfo(
+                asUid, requests, nr, msgr, binder, callbackFlags, callingAttributionTag);
+    }
+
+    private void enforceNetworkRequestPermissions(NetworkCapabilities networkCapabilities,
+            String callingPackageName, String callingAttributionTag) {
+        if (networkCapabilities.hasCapability(NET_CAPABILITY_NOT_RESTRICTED) == false) {
+            enforceConnectivityRestrictedNetworksPermission();
+        } else {
+            enforceChangePermission(callingPackageName, callingAttributionTag);
+        }
+    }
+
+    @Override
+    public boolean requestBandwidthUpdate(Network network) {
+        enforceAccessPermission();
+        NetworkAgentInfo nai = null;
+        if (network == null) {
+            return false;
+        }
+        synchronized (mNetworkForNetId) {
+            nai = mNetworkForNetId.get(network.getNetId());
+        }
+        if (nai != null) {
+            nai.onBandwidthUpdateRequested();
+            synchronized (mBandwidthRequests) {
+                final int uid = mDeps.getCallingUid();
+                Integer uidReqs = mBandwidthRequests.get(uid);
+                if (uidReqs == null) {
+                    uidReqs = 0;
+                }
+                mBandwidthRequests.put(uid, ++uidReqs);
+            }
+            return true;
+        }
+        return false;
+    }
+
+    private boolean isSystem(int uid) {
+        return uid < Process.FIRST_APPLICATION_UID;
+    }
+
+    private void enforceMeteredApnPolicy(NetworkCapabilities networkCapabilities) {
+        final int uid = mDeps.getCallingUid();
+        if (isSystem(uid)) {
+            // Exemption for system uid.
+            return;
+        }
+        if (networkCapabilities.hasCapability(NET_CAPABILITY_NOT_METERED)) {
+            // Policy already enforced.
+            return;
+        }
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            if (mPolicyManager.isUidRestrictedOnMeteredNetworks(uid)) {
+                // If UID is restricted, don't allow them to bring up metered APNs.
+                networkCapabilities.addCapability(NET_CAPABILITY_NOT_METERED);
+            }
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+    }
+
+    @Override
+    public NetworkRequest pendingRequestForNetwork(NetworkCapabilities networkCapabilities,
+            PendingIntent operation, @NonNull String callingPackageName,
+            @Nullable String callingAttributionTag) {
+        Objects.requireNonNull(operation, "PendingIntent cannot be null.");
+        final int callingUid = mDeps.getCallingUid();
+        networkCapabilities = new NetworkCapabilities(networkCapabilities);
+        enforceNetworkRequestPermissions(networkCapabilities, callingPackageName,
+                callingAttributionTag);
+        enforceMeteredApnPolicy(networkCapabilities);
+        ensureRequestableCapabilities(networkCapabilities);
+        ensureSufficientPermissionsForRequest(networkCapabilities,
+                Binder.getCallingPid(), callingUid, callingPackageName);
+        ensureValidNetworkSpecifier(networkCapabilities);
+        restrictRequestUidsForCallerAndSetRequestorInfo(networkCapabilities,
+                callingUid, callingPackageName);
+
+        NetworkRequest networkRequest = new NetworkRequest(networkCapabilities, TYPE_NONE,
+                nextNetworkRequestId(), NetworkRequest.Type.REQUEST);
+        NetworkRequestInfo nri = new NetworkRequestInfo(callingUid, networkRequest, operation,
+                callingAttributionTag);
+        if (DBG) log("pendingRequest for " + nri);
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_REGISTER_NETWORK_REQUEST_WITH_INTENT,
+                nri));
+        return networkRequest;
+    }
+
+    private void releasePendingNetworkRequestWithDelay(PendingIntent operation) {
+        mHandler.sendMessageDelayed(
+                mHandler.obtainMessage(EVENT_RELEASE_NETWORK_REQUEST_WITH_INTENT,
+                mDeps.getCallingUid(), 0, operation), mReleasePendingIntentDelayMs);
+    }
+
+    @Override
+    public void releasePendingNetworkRequest(PendingIntent operation) {
+        Objects.requireNonNull(operation, "PendingIntent cannot be null.");
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_RELEASE_NETWORK_REQUEST_WITH_INTENT,
+                mDeps.getCallingUid(), 0, operation));
+    }
+
+    // In order to implement the compatibility measure for pre-M apps that call
+    // WifiManager.enableNetwork(..., true) without also binding to that network explicitly,
+    // WifiManager registers a network listen for the purpose of calling setProcessDefaultNetwork.
+    // This ensures it has permission to do so.
+    private boolean hasWifiNetworkListenPermission(NetworkCapabilities nc) {
+        if (nc == null) {
+            return false;
+        }
+        int[] transportTypes = nc.getTransportTypes();
+        if (transportTypes.length != 1 || transportTypes[0] != NetworkCapabilities.TRANSPORT_WIFI) {
+            return false;
+        }
+        try {
+            mContext.enforceCallingOrSelfPermission(
+                    android.Manifest.permission.ACCESS_WIFI_STATE,
+                    "ConnectivityService");
+        } catch (SecurityException e) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public NetworkRequest listenForNetwork(NetworkCapabilities networkCapabilities,
+            Messenger messenger, IBinder binder,
+            @NetworkCallback.Flag int callbackFlags,
+            @NonNull String callingPackageName, @NonNull String callingAttributionTag) {
+        final int callingUid = mDeps.getCallingUid();
+        if (!hasWifiNetworkListenPermission(networkCapabilities)) {
+            enforceAccessPermission();
+        }
+
+        NetworkCapabilities nc = new NetworkCapabilities(networkCapabilities);
+        ensureSufficientPermissionsForRequest(networkCapabilities,
+                Binder.getCallingPid(), callingUid, callingPackageName);
+        restrictRequestUidsForCallerAndSetRequestorInfo(nc, callingUid, callingPackageName);
+        // Apps without the CHANGE_NETWORK_STATE permission can't use background networks, so
+        // make all their listens include NET_CAPABILITY_FOREGROUND. That way, they will get
+        // onLost and onAvailable callbacks when networks move in and out of the background.
+        // There is no need to do this for requests because an app without CHANGE_NETWORK_STATE
+        // can't request networks.
+        restrictBackgroundRequestForCaller(nc);
+        ensureValid(nc);
+
+        NetworkRequest networkRequest = new NetworkRequest(nc, TYPE_NONE, nextNetworkRequestId(),
+                NetworkRequest.Type.LISTEN);
+        NetworkRequestInfo nri =
+                new NetworkRequestInfo(callingUid, networkRequest, messenger, binder, callbackFlags,
+                        callingAttributionTag);
+        if (VDBG) log("listenForNetwork for " + nri);
+
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_REGISTER_NETWORK_LISTENER, nri));
+        return networkRequest;
+    }
+
+    @Override
+    public void pendingListenForNetwork(NetworkCapabilities networkCapabilities,
+            PendingIntent operation, @NonNull String callingPackageName,
+            @Nullable String callingAttributionTag) {
+        Objects.requireNonNull(operation, "PendingIntent cannot be null.");
+        final int callingUid = mDeps.getCallingUid();
+        if (!hasWifiNetworkListenPermission(networkCapabilities)) {
+            enforceAccessPermission();
+        }
+        ensureValid(networkCapabilities);
+        ensureSufficientPermissionsForRequest(networkCapabilities,
+                Binder.getCallingPid(), callingUid, callingPackageName);
+        final NetworkCapabilities nc = new NetworkCapabilities(networkCapabilities);
+        restrictRequestUidsForCallerAndSetRequestorInfo(nc, callingUid, callingPackageName);
+
+        NetworkRequest networkRequest = new NetworkRequest(nc, TYPE_NONE, nextNetworkRequestId(),
+                NetworkRequest.Type.LISTEN);
+        NetworkRequestInfo nri = new NetworkRequestInfo(callingUid, networkRequest, operation,
+                callingAttributionTag);
+        if (VDBG) log("pendingListenForNetwork for " + nri);
+
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_REGISTER_NETWORK_LISTENER, nri));
+    }
+
+    /** Returns the next Network provider ID. */
+    public final int nextNetworkProviderId() {
+        return mNextNetworkProviderId.getAndIncrement();
+    }
+
+    private void releaseNetworkRequests(List<NetworkRequest> networkRequests) {
+        for (int i = 0; i < networkRequests.size(); i++) {
+            releaseNetworkRequest(networkRequests.get(i));
+        }
+    }
+
+    @Override
+    public void releaseNetworkRequest(NetworkRequest networkRequest) {
+        ensureNetworkRequestHasType(networkRequest);
+        mHandler.sendMessage(mHandler.obtainMessage(
+                EVENT_RELEASE_NETWORK_REQUEST, mDeps.getCallingUid(), 0, networkRequest));
+    }
+
+    private void handleRegisterNetworkProvider(NetworkProviderInfo npi) {
+        if (mNetworkProviderInfos.containsKey(npi.messenger)) {
+            // Avoid creating duplicates. even if an app makes a direct AIDL call.
+            // This will never happen if an app calls ConnectivityManager#registerNetworkProvider,
+            // as that will throw if a duplicate provider is registered.
+            loge("Attempt to register existing NetworkProviderInfo "
+                    + mNetworkProviderInfos.get(npi.messenger).name);
+            return;
+        }
+
+        if (DBG) log("Got NetworkProvider Messenger for " + npi.name);
+        mNetworkProviderInfos.put(npi.messenger, npi);
+        npi.connect(mContext, mTrackerHandler);
+    }
+
+    @Override
+    public int registerNetworkProvider(Messenger messenger, String name) {
+        enforceNetworkFactoryOrSettingsPermission();
+        Objects.requireNonNull(messenger, "messenger must be non-null");
+        NetworkProviderInfo npi = new NetworkProviderInfo(name, messenger,
+                nextNetworkProviderId(), () -> unregisterNetworkProvider(messenger));
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_REGISTER_NETWORK_PROVIDER, npi));
+        return npi.providerId;
+    }
+
+    @Override
+    public void unregisterNetworkProvider(Messenger messenger) {
+        enforceNetworkFactoryOrSettingsPermission();
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_UNREGISTER_NETWORK_PROVIDER, messenger));
+    }
+
+    @Override
+    public void offerNetwork(final int providerId,
+            @NonNull final NetworkScore score, @NonNull final NetworkCapabilities caps,
+            @NonNull final INetworkOfferCallback callback) {
+        Objects.requireNonNull(score);
+        Objects.requireNonNull(caps);
+        Objects.requireNonNull(callback);
+        final NetworkOffer offer = new NetworkOffer(
+                FullScore.makeProspectiveScore(score, caps), caps, callback, providerId);
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_REGISTER_NETWORK_OFFER, offer));
+    }
+
+    @Override
+    public void unofferNetwork(@NonNull final INetworkOfferCallback callback) {
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_UNREGISTER_NETWORK_OFFER, callback));
+    }
+
+    private void handleUnregisterNetworkProvider(Messenger messenger) {
+        NetworkProviderInfo npi = mNetworkProviderInfos.remove(messenger);
+        if (npi == null) {
+            loge("Failed to find Messenger in unregisterNetworkProvider");
+            return;
+        }
+        // Unregister all the offers from this provider
+        final ArrayList<NetworkOfferInfo> toRemove = new ArrayList<>();
+        for (final NetworkOfferInfo noi : mNetworkOffers) {
+            if (noi.offer.providerId == npi.providerId) {
+                // Can't call handleUnregisterNetworkOffer here because iteration is in progress
+                toRemove.add(noi);
+            }
+        }
+        for (final NetworkOfferInfo noi : toRemove) {
+            handleUnregisterNetworkOffer(noi);
+        }
+        if (DBG) log("unregisterNetworkProvider for " + npi.name);
+    }
+
+    @Override
+    public void declareNetworkRequestUnfulfillable(@NonNull final NetworkRequest request) {
+        if (request.hasTransport(TRANSPORT_TEST)) {
+            enforceNetworkFactoryOrTestNetworksPermission();
+        } else {
+            enforceNetworkFactoryPermission();
+        }
+        final NetworkRequestInfo nri = mNetworkRequests.get(request);
+        if (nri != null) {
+            // declareNetworkRequestUnfulfillable() paths don't apply to multilayer requests.
+            ensureNotMultilayerRequest(nri, "declareNetworkRequestUnfulfillable");
+            mHandler.post(() -> handleReleaseNetworkRequest(
+                    nri.mRequests.get(0), mDeps.getCallingUid(), true));
+        }
+    }
+
+    // NOTE: Accessed on multiple threads, must be synchronized on itself.
+    @GuardedBy("mNetworkForNetId")
+    private final SparseArray<NetworkAgentInfo> mNetworkForNetId = new SparseArray<>();
+    // NOTE: Accessed on multiple threads, synchronized with mNetworkForNetId.
+    // An entry is first reserved with NetIdManager, prior to being added to mNetworkForNetId, so
+    // there may not be a strict 1:1 correlation between the two.
+    private final NetIdManager mNetIdManager;
+
+    // NetworkAgentInfo keyed off its connecting messenger
+    // TODO - eval if we can reduce the number of lists/hashmaps/sparsearrays
+    // NOTE: Only should be accessed on ConnectivityServiceThread, except dump().
+    private final ArraySet<NetworkAgentInfo> mNetworkAgentInfos = new ArraySet<>();
+
+    // UID ranges for users that are currently blocked by VPNs.
+    // This array is accessed and iterated on multiple threads without holding locks, so its
+    // contents must never be mutated. When the ranges change, the array is replaced with a new one
+    // (on the handler thread).
+    private volatile List<UidRange> mVpnBlockedUidRanges = new ArrayList<>();
+
+    // Must only be accessed on the handler thread
+    @NonNull
+    private final ArrayList<NetworkOfferInfo> mNetworkOffers = new ArrayList<>();
+
+    @GuardedBy("mBlockedAppUids")
+    private final HashSet<Integer> mBlockedAppUids = new HashSet<>();
+
+    // Current OEM network preferences. This object must only be written to on the handler thread.
+    // Since it is immutable and always non-null, other threads may read it if they only care
+    // about seeing a consistent object but not that it is current.
+    @NonNull
+    private OemNetworkPreferences mOemNetworkPreferences =
+            new OemNetworkPreferences.Builder().build();
+    // Current per-profile network preferences. This object follows the same threading rules as
+    // the OEM network preferences above.
+    @NonNull
+    private ProfileNetworkPreferences mProfileNetworkPreferences = new ProfileNetworkPreferences();
+
+    // OemNetworkPreferences activity String log entries.
+    private static final int MAX_OEM_NETWORK_PREFERENCE_LOGS = 20;
+    @NonNull
+    private final LocalLog mOemNetworkPreferencesLogs =
+            new LocalLog(MAX_OEM_NETWORK_PREFERENCE_LOGS);
+
+    /**
+     * Determine whether a given package has a mapping in the current OemNetworkPreferences.
+     * @param packageName the package name to check existence of a mapping for.
+     * @return true if a mapping exists, false otherwise
+     */
+    private boolean isMappedInOemNetworkPreference(@NonNull final String packageName) {
+        return mOemNetworkPreferences.getNetworkPreferences().containsKey(packageName);
+    }
+
+    // The always-on request for an Internet-capable network that apps without a specific default
+    // fall back to.
+    @VisibleForTesting
+    @NonNull
+    final NetworkRequestInfo mDefaultRequest;
+    // Collection of NetworkRequestInfo's used for default networks.
+    @VisibleForTesting
+    @NonNull
+    final ArraySet<NetworkRequestInfo> mDefaultNetworkRequests = new ArraySet<>();
+
+    private boolean isPerAppDefaultRequest(@NonNull final NetworkRequestInfo nri) {
+        return (mDefaultNetworkRequests.contains(nri) && mDefaultRequest != nri);
+    }
+
+    /**
+     * Return the default network request currently tracking the given uid.
+     * @param uid the uid to check.
+     * @return the NetworkRequestInfo tracking the given uid.
+     */
+    @NonNull
+    private NetworkRequestInfo getDefaultRequestTrackingUid(final int uid) {
+        for (final NetworkRequestInfo nri : mDefaultNetworkRequests) {
+            if (nri == mDefaultRequest) {
+                continue;
+            }
+            // Checking the first request is sufficient as only multilayer requests will have more
+            // than one request and for multilayer, all requests will track the same uids.
+            if (nri.mRequests.get(0).networkCapabilities.appliesToUid(uid)) {
+                return nri;
+            }
+        }
+        return mDefaultRequest;
+    }
+
+    /**
+     * Get a copy of the network requests of the default request that is currently tracking the
+     * given uid.
+     * @param asUid the uid on behalf of which to file the request. Different from requestorUid
+     *              when a privileged caller is tracking the default network for another uid.
+     * @param requestorUid the uid to check the default for.
+     * @param requestorPackageName the requestor's package name.
+     * @return a copy of the default's NetworkRequest that is tracking the given uid.
+     */
+    @NonNull
+    private List<NetworkRequest> copyDefaultNetworkRequestsForUid(
+            final int asUid, final int requestorUid, @NonNull final String requestorPackageName) {
+        return copyNetworkRequestsForUid(
+                getDefaultRequestTrackingUid(asUid).mRequests,
+                asUid, requestorUid, requestorPackageName);
+    }
+
+    /**
+     * Copy the given nri's NetworkRequest collection.
+     * @param requestsToCopy the NetworkRequest collection to be copied.
+     * @param asUid the uid on behalf of which to file the request. Different from requestorUid
+     *              when a privileged caller is tracking the default network for another uid.
+     * @param requestorUid the uid to set on the copied collection.
+     * @param requestorPackageName the package name to set on the copied collection.
+     * @return the copied NetworkRequest collection.
+     */
+    @NonNull
+    private List<NetworkRequest> copyNetworkRequestsForUid(
+            @NonNull final List<NetworkRequest> requestsToCopy, final int asUid,
+            final int requestorUid, @NonNull final String requestorPackageName) {
+        final List<NetworkRequest> requests = new ArrayList<>();
+        for (final NetworkRequest nr : requestsToCopy) {
+            requests.add(new NetworkRequest(copyDefaultNetworkCapabilitiesForUid(
+                            nr.networkCapabilities, asUid, requestorUid, requestorPackageName),
+                    nr.legacyType, nextNetworkRequestId(), nr.type));
+        }
+        return requests;
+    }
+
+    @NonNull
+    private NetworkCapabilities copyDefaultNetworkCapabilitiesForUid(
+            @NonNull final NetworkCapabilities netCapToCopy, final int asUid,
+            final int requestorUid, @NonNull final String requestorPackageName) {
+        // These capabilities are for a TRACK_DEFAULT callback, so:
+        // 1. Remove NET_CAPABILITY_VPN, because it's (currently!) the only difference between
+        //    mDefaultRequest and a per-UID default request.
+        //    TODO: stop depending on the fact that these two unrelated things happen to be the same
+        // 2. Always set the UIDs to asUid. restrictRequestUidsForCallerAndSetRequestorInfo will
+        //    not do this in the case of a privileged application.
+        final NetworkCapabilities netCap = new NetworkCapabilities(netCapToCopy);
+        netCap.removeCapability(NET_CAPABILITY_NOT_VPN);
+        netCap.setSingleUid(asUid);
+        restrictRequestUidsForCallerAndSetRequestorInfo(
+                netCap, requestorUid, requestorPackageName);
+        return netCap;
+    }
+
+    /**
+     * Get the nri that is currently being tracked for callbacks by per-app defaults.
+     * @param nr the network request to check for equality against.
+     * @return the nri if one exists, null otherwise.
+     */
+    @Nullable
+    private NetworkRequestInfo getNriForAppRequest(@NonNull final NetworkRequest nr) {
+        for (final NetworkRequestInfo nri : mNetworkRequests.values()) {
+            if (nri.getNetworkRequestForCallback().equals(nr)) {
+                return nri;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Check if an nri is currently being managed by per-app default networking.
+     * @param nri the nri to check.
+     * @return true if this nri is currently being managed by per-app default networking.
+     */
+    private boolean isPerAppTrackedNri(@NonNull final NetworkRequestInfo nri) {
+        // nri.mRequests.get(0) is only different from the original request filed in
+        // nri.getNetworkRequestForCallback() if nri.mRequests was changed by per-app default
+        // functionality therefore if these two don't match, it means this particular nri is
+        // currently being managed by a per-app default.
+        return nri.getNetworkRequestForCallback() != nri.mRequests.get(0);
+    }
+
+    /**
+     * Determine if an nri is a managed default request that disallows default networking.
+     * @param nri the request to evaluate
+     * @return true if device-default networking is disallowed
+     */
+    private boolean isDefaultBlocked(@NonNull final NetworkRequestInfo nri) {
+        // Check if this nri is a managed default that supports the default network at its
+        // lowest priority request.
+        final NetworkRequest defaultNetworkRequest = mDefaultRequest.mRequests.get(0);
+        final NetworkCapabilities lowestPriorityNetCap =
+                nri.mRequests.get(nri.mRequests.size() - 1).networkCapabilities;
+        return isPerAppDefaultRequest(nri)
+                && !(defaultNetworkRequest.networkCapabilities.equalRequestableCapabilities(
+                        lowestPriorityNetCap));
+    }
+
+    // Request used to optionally keep mobile data active even when higher
+    // priority networks like Wi-Fi are active.
+    private final NetworkRequest mDefaultMobileDataRequest;
+
+    // Request used to optionally keep wifi data active even when higher
+    // priority networks like ethernet are active.
+    private final NetworkRequest mDefaultWifiRequest;
+
+    // Request used to optionally keep vehicle internal network always active
+    private final NetworkRequest mDefaultVehicleRequest;
+
+    // TODO replace with INetd.UNREACHABLE_NET_ID when available.
+    private static final int NO_SERVICE_NET_ID = 52;
+    // Sentinel NAI used to direct apps with default networks that should have no connectivity to a
+    // network with no service. This NAI should never be matched against, nor should any public API
+    // ever return the associated network. For this reason, this NAI is not in the list of available
+    // NAIs. It is used in computeNetworkReassignment() to be set as the satisfier for non-device
+    // default requests that don't support using the device default network which will ultimately
+    // allow ConnectivityService to use this no-service network when calling makeDefaultForApps().
+    @VisibleForTesting
+    final NetworkAgentInfo mNoServiceNetwork;
+
+    // The NetworkAgentInfo currently satisfying the default request, if any.
+    private NetworkAgentInfo getDefaultNetwork() {
+        return mDefaultRequest.mSatisfier;
+    }
+
+    private NetworkAgentInfo getDefaultNetworkForUid(final int uid) {
+        for (final NetworkRequestInfo nri : mDefaultNetworkRequests) {
+            // Currently, all network requests will have the same uids therefore checking the first
+            // one is sufficient. If/when uids are tracked at the nri level, this can change.
+            final Set<UidRange> uids = nri.mRequests.get(0).networkCapabilities.getUidRanges();
+            if (null == uids) {
+                continue;
+            }
+            for (final UidRange range : uids) {
+                if (range.contains(uid)) {
+                    return nri.getSatisfier();
+                }
+            }
+        }
+        return getDefaultNetwork();
+    }
+
+    @Nullable
+    private Network getNetwork(@Nullable NetworkAgentInfo nai) {
+        return nai != null ? nai.network : null;
+    }
+
+    private void ensureRunningOnConnectivityServiceThread() {
+        if (mHandler.getLooper().getThread() != Thread.currentThread()) {
+            throw new IllegalStateException(
+                    "Not running on ConnectivityService thread: "
+                            + Thread.currentThread().getName());
+        }
+    }
+
+    @VisibleForTesting
+    protected boolean isDefaultNetwork(NetworkAgentInfo nai) {
+        return nai == getDefaultNetwork();
+    }
+
+    /**
+     * Register a new agent with ConnectivityService to handle a network.
+     *
+     * @param na a reference for ConnectivityService to contact the agent asynchronously.
+     * @param networkInfo the initial info associated with this network. It can be updated later :
+     *         see {@link #updateNetworkInfo}.
+     * @param linkProperties the initial link properties of this network. They can be updated
+     *         later : see {@link #updateLinkProperties}.
+     * @param networkCapabilities the initial capabilites of this network. They can be updated
+     *         later : see {@link #updateCapabilities}.
+     * @param initialScore the initial score of the network. See
+     *         {@link NetworkAgentInfo#getCurrentScore}.
+     * @param networkAgentConfig metadata about the network. This is never updated.
+     * @param providerId the ID of the provider owning this NetworkAgent.
+     * @return the network created for this agent.
+     */
+    public Network registerNetworkAgent(INetworkAgent na, NetworkInfo networkInfo,
+            LinkProperties linkProperties, NetworkCapabilities networkCapabilities,
+            @NonNull NetworkScore initialScore, NetworkAgentConfig networkAgentConfig,
+            int providerId) {
+        Objects.requireNonNull(networkInfo, "networkInfo must not be null");
+        Objects.requireNonNull(linkProperties, "linkProperties must not be null");
+        Objects.requireNonNull(networkCapabilities, "networkCapabilities must not be null");
+        Objects.requireNonNull(initialScore, "initialScore must not be null");
+        Objects.requireNonNull(networkAgentConfig, "networkAgentConfig must not be null");
+        if (networkCapabilities.hasTransport(TRANSPORT_TEST)) {
+            enforceAnyPermissionOf(Manifest.permission.MANAGE_TEST_NETWORKS);
+        } else {
+            enforceNetworkFactoryPermission();
+        }
+
+        final int uid = mDeps.getCallingUid();
+        final long token = Binder.clearCallingIdentity();
+        try {
+            return registerNetworkAgentInternal(na, networkInfo, linkProperties,
+                    networkCapabilities, initialScore, networkAgentConfig, providerId, uid);
+        } finally {
+            Binder.restoreCallingIdentity(token);
+        }
+    }
+
+    private Network registerNetworkAgentInternal(INetworkAgent na, NetworkInfo networkInfo,
+            LinkProperties linkProperties, NetworkCapabilities networkCapabilities,
+            NetworkScore currentScore, NetworkAgentConfig networkAgentConfig, int providerId,
+            int uid) {
+        if (networkCapabilities.hasTransport(TRANSPORT_TEST)) {
+            // Strictly, sanitizing here is unnecessary as the capabilities will be sanitized in
+            // the call to mixInCapabilities below anyway, but sanitizing here means the NAI never
+            // sees capabilities that may be malicious, which might prevent mistakes in the future.
+            networkCapabilities = new NetworkCapabilities(networkCapabilities);
+            networkCapabilities.restrictCapabilitesForTestNetwork(uid);
+        }
+
+        LinkProperties lp = new LinkProperties(linkProperties);
+
+        final NetworkCapabilities nc = new NetworkCapabilities(networkCapabilities);
+        final NetworkAgentInfo nai = new NetworkAgentInfo(na,
+                new Network(mNetIdManager.reserveNetId()), new NetworkInfo(networkInfo), lp, nc,
+                currentScore, mContext, mTrackerHandler, new NetworkAgentConfig(networkAgentConfig),
+                this, mNetd, mDnsResolver, providerId, uid, mLingerDelayMs,
+                mQosCallbackTracker, mDeps);
+
+        // Make sure the LinkProperties and NetworkCapabilities reflect what the agent info says.
+        processCapabilitiesFromAgent(nai, nc);
+        nai.getAndSetNetworkCapabilities(mixInCapabilities(nai, nc));
+        processLinkPropertiesFromAgent(nai, nai.linkProperties);
+
+        final String extraInfo = networkInfo.getExtraInfo();
+        final String name = TextUtils.isEmpty(extraInfo)
+                ? nai.networkCapabilities.getSsid() : extraInfo;
+        if (DBG) log("registerNetworkAgent " + nai);
+        mDeps.getNetworkStack().makeNetworkMonitor(
+                nai.network, name, new NetworkMonitorCallbacks(nai));
+        // NetworkAgentInfo registration will finish when the NetworkMonitor is created.
+        // If the network disconnects or sends any other event before that, messages are deferred by
+        // NetworkAgent until nai.connect(), which will be called when finalizing the
+        // registration.
+        return nai.network;
+    }
+
+    private void handleRegisterNetworkAgent(NetworkAgentInfo nai, INetworkMonitor networkMonitor) {
+        nai.onNetworkMonitorCreated(networkMonitor);
+        if (VDBG) log("Got NetworkAgent Messenger");
+        mNetworkAgentInfos.add(nai);
+        synchronized (mNetworkForNetId) {
+            mNetworkForNetId.put(nai.network.getNetId(), nai);
+        }
+
+        try {
+            networkMonitor.start();
+        } catch (RemoteException e) {
+            e.rethrowAsRuntimeException();
+        }
+        nai.notifyRegistered();
+        NetworkInfo networkInfo = nai.networkInfo;
+        updateNetworkInfo(nai, networkInfo);
+        updateUids(nai, null, nai.networkCapabilities);
+    }
+
+    private class NetworkOfferInfo implements IBinder.DeathRecipient {
+        @NonNull public final NetworkOffer offer;
+
+        NetworkOfferInfo(@NonNull final NetworkOffer offer) {
+            this.offer = offer;
+        }
+
+        @Override
+        public void binderDied() {
+            mHandler.post(() -> handleUnregisterNetworkOffer(this));
+        }
+    }
+
+    private boolean isNetworkProviderWithIdRegistered(final int providerId) {
+        for (final NetworkProviderInfo npi : mNetworkProviderInfos.values()) {
+            if (npi.providerId == providerId) return true;
+        }
+        return false;
+    }
+
+    /**
+     * Register or update a network offer.
+     * @param newOffer The new offer. If the callback member is the same as an existing
+     *                 offer, it is an update of that offer.
+     */
+    private void handleRegisterNetworkOffer(@NonNull final NetworkOffer newOffer) {
+        ensureRunningOnConnectivityServiceThread();
+        if (!isNetworkProviderWithIdRegistered(newOffer.providerId)) {
+            // This may actually happen if a provider updates its score or registers and then
+            // immediately unregisters. The offer would still be in the handler queue, but the
+            // provider would have been removed.
+            if (DBG) log("Received offer from an unregistered provider");
+            return;
+        }
+        final NetworkOfferInfo existingOffer = findNetworkOfferInfoByCallback(newOffer.callback);
+        if (null != existingOffer) {
+            handleUnregisterNetworkOffer(existingOffer);
+            newOffer.migrateFrom(existingOffer.offer);
+        }
+        final NetworkOfferInfo noi = new NetworkOfferInfo(newOffer);
+        try {
+            noi.offer.callback.asBinder().linkToDeath(noi, 0 /* flags */);
+        } catch (RemoteException e) {
+            noi.binderDied();
+            return;
+        }
+        mNetworkOffers.add(noi);
+        issueNetworkNeeds(noi);
+    }
+
+    private void handleUnregisterNetworkOffer(@NonNull final NetworkOfferInfo noi) {
+        ensureRunningOnConnectivityServiceThread();
+        mNetworkOffers.remove(noi);
+        noi.offer.callback.asBinder().unlinkToDeath(noi, 0 /* flags */);
+    }
+
+    @Nullable private NetworkOfferInfo findNetworkOfferInfoByCallback(
+            @NonNull final INetworkOfferCallback callback) {
+        ensureRunningOnConnectivityServiceThread();
+        for (final NetworkOfferInfo noi : mNetworkOffers) {
+            if (noi.offer.callback.asBinder().equals(callback.asBinder())) return noi;
+        }
+        return null;
+    }
+
+    /**
+     * Called when receiving LinkProperties directly from a NetworkAgent.
+     * Stores into |nai| any data coming from the agent that might also be written to the network's
+     * LinkProperties by ConnectivityService itself. This ensures that the data provided by the
+     * agent is not lost when updateLinkProperties is called.
+     * This method should never alter the agent's LinkProperties, only store data in |nai|.
+     */
+    private void processLinkPropertiesFromAgent(NetworkAgentInfo nai, LinkProperties lp) {
+        lp.ensureDirectlyConnectedRoutes();
+        nai.clatd.setNat64PrefixFromRa(lp.getNat64Prefix());
+        nai.networkAgentPortalData = lp.getCaptivePortalData();
+    }
+
+    private void updateLinkProperties(NetworkAgentInfo networkAgent, @NonNull LinkProperties newLp,
+            @NonNull LinkProperties oldLp) {
+        int netId = networkAgent.network.getNetId();
+
+        // The NetworkAgent does not know whether clatd is running on its network or not, or whether
+        // a NAT64 prefix was discovered by the DNS resolver. Before we do anything else, make sure
+        // the LinkProperties for the network are accurate.
+        networkAgent.clatd.fixupLinkProperties(oldLp, newLp);
+
+        updateInterfaces(newLp, oldLp, netId, networkAgent.networkCapabilities);
+
+        // update filtering rules, need to happen after the interface update so netd knows about the
+        // new interface (the interface name -> index map becomes initialized)
+        updateVpnFiltering(newLp, oldLp, networkAgent);
+
+        updateMtu(newLp, oldLp);
+        // TODO - figure out what to do for clat
+//        for (LinkProperties lp : newLp.getStackedLinks()) {
+//            updateMtu(lp, null);
+//        }
+        if (isDefaultNetwork(networkAgent)) {
+            updateTcpBufferSizes(newLp.getTcpBufferSizes());
+        }
+
+        updateRoutes(newLp, oldLp, netId);
+        updateDnses(newLp, oldLp, netId);
+        // Make sure LinkProperties represents the latest private DNS status.
+        // This does not need to be done before updateDnses because the
+        // LinkProperties are not the source of the private DNS configuration.
+        // updateDnses will fetch the private DNS configuration from DnsManager.
+        mDnsManager.updatePrivateDnsStatus(netId, newLp);
+
+        if (isDefaultNetwork(networkAgent)) {
+            handleApplyDefaultProxy(newLp.getHttpProxy());
+        } else {
+            updateProxy(newLp, oldLp);
+        }
+
+        updateWakeOnLan(newLp);
+
+        // Captive portal data is obtained from NetworkMonitor and stored in NetworkAgentInfo.
+        // It is not always contained in the LinkProperties sent from NetworkAgents, and if it
+        // does, it needs to be merged here.
+        newLp.setCaptivePortalData(mergeCaptivePortalData(networkAgent.networkAgentPortalData,
+                networkAgent.capportApiData));
+
+        // TODO - move this check to cover the whole function
+        if (!Objects.equals(newLp, oldLp)) {
+            synchronized (networkAgent) {
+                networkAgent.linkProperties = newLp;
+            }
+            // Start or stop DNS64 detection and 464xlat according to network state.
+            networkAgent.clatd.update();
+            notifyIfacesChangedForNetworkStats();
+            networkAgent.networkMonitor().notifyLinkPropertiesChanged(
+                    new LinkProperties(newLp, true /* parcelSensitiveFields */));
+            if (networkAgent.everConnected) {
+                notifyNetworkCallbacks(networkAgent, ConnectivityManager.CALLBACK_IP_CHANGED);
+            }
+        }
+
+        mKeepaliveTracker.handleCheckKeepalivesStillValid(networkAgent);
+    }
+
+    /**
+     * @param naData captive portal data from NetworkAgent
+     * @param apiData captive portal data from capport API
+     */
+    @Nullable
+    private CaptivePortalData mergeCaptivePortalData(CaptivePortalData naData,
+            CaptivePortalData apiData) {
+        if (naData == null || apiData == null) {
+            return naData == null ? apiData : naData;
+        }
+        final CaptivePortalData.Builder captivePortalBuilder =
+                new CaptivePortalData.Builder(naData);
+
+        if (apiData.isCaptive()) {
+            captivePortalBuilder.setCaptive(true);
+        }
+        if (apiData.isSessionExtendable()) {
+            captivePortalBuilder.setSessionExtendable(true);
+        }
+        if (apiData.getExpiryTimeMillis() >= 0 || apiData.getByteLimit() >= 0) {
+            // Expiry time, bytes remaining, refresh time all need to come from the same source,
+            // otherwise data would be inconsistent. Prefer the capport API info if present,
+            // as it can generally be refreshed more often.
+            captivePortalBuilder.setExpiryTime(apiData.getExpiryTimeMillis());
+            captivePortalBuilder.setBytesRemaining(apiData.getByteLimit());
+            captivePortalBuilder.setRefreshTime(apiData.getRefreshTimeMillis());
+        } else if (naData.getExpiryTimeMillis() < 0 && naData.getByteLimit() < 0) {
+            // No source has time / bytes remaining information: surface the newest refresh time
+            // for other fields
+            captivePortalBuilder.setRefreshTime(
+                    Math.max(naData.getRefreshTimeMillis(), apiData.getRefreshTimeMillis()));
+        }
+
+        // Prioritize the user portal URL from the network agent if the source is authenticated.
+        if (apiData.getUserPortalUrl() != null && naData.getUserPortalUrlSource()
+                != CaptivePortalData.CAPTIVE_PORTAL_DATA_SOURCE_PASSPOINT) {
+            captivePortalBuilder.setUserPortalUrl(apiData.getUserPortalUrl(),
+                    apiData.getUserPortalUrlSource());
+        }
+        // Prioritize the venue information URL from the network agent if the source is
+        // authenticated.
+        if (apiData.getVenueInfoUrl() != null && naData.getVenueInfoUrlSource()
+                != CaptivePortalData.CAPTIVE_PORTAL_DATA_SOURCE_PASSPOINT) {
+            captivePortalBuilder.setVenueInfoUrl(apiData.getVenueInfoUrl(),
+                    apiData.getVenueInfoUrlSource());
+        }
+        return captivePortalBuilder.build();
+    }
+
+    private void wakeupModifyInterface(String iface, NetworkCapabilities caps, boolean add) {
+        // Marks are only available on WiFi interfaces. Checking for
+        // marks on unsupported interfaces is harmless.
+        if (!caps.hasTransport(NetworkCapabilities.TRANSPORT_WIFI)) {
+            return;
+        }
+
+        int mark = mResources.get().getInteger(R.integer.config_networkWakeupPacketMark);
+        int mask = mResources.get().getInteger(R.integer.config_networkWakeupPacketMask);
+
+        // TODO (b/183076074): remove legacy fallback after migrating overlays
+        final int legacyMark = mContext.getResources().getInteger(mContext.getResources()
+                .getIdentifier("config_networkWakeupPacketMark", "integer", "android"));
+        final int legacyMask = mContext.getResources().getInteger(mContext.getResources()
+                .getIdentifier("config_networkWakeupPacketMask", "integer", "android"));
+        mark = mark == 0 ? legacyMark : mark;
+        mask = mask == 0 ? legacyMask : mask;
+
+        // Mask/mark of zero will not detect anything interesting.
+        // Don't install rules unless both values are nonzero.
+        if (mark == 0 || mask == 0) {
+            return;
+        }
+
+        final String prefix = "iface:" + iface;
+        try {
+            if (add) {
+                mNetd.wakeupAddInterface(iface, prefix, mark, mask);
+            } else {
+                mNetd.wakeupDelInterface(iface, prefix, mark, mask);
+            }
+        } catch (Exception e) {
+            loge("Exception modifying wakeup packet monitoring: " + e);
+        }
+
+    }
+
+    private void updateInterfaces(final @Nullable LinkProperties newLp,
+            final @Nullable LinkProperties oldLp, final int netId,
+            final @NonNull NetworkCapabilities caps) {
+        final CompareResult<String> interfaceDiff = new CompareResult<>(
+                oldLp != null ? oldLp.getAllInterfaceNames() : null,
+                newLp != null ? newLp.getAllInterfaceNames() : null);
+        if (!interfaceDiff.added.isEmpty()) {
+            for (final String iface : interfaceDiff.added) {
+                try {
+                    if (DBG) log("Adding iface " + iface + " to network " + netId);
+                    mNetd.networkAddInterface(netId, iface);
+                    wakeupModifyInterface(iface, caps, true);
+                    mDeps.reportNetworkInterfaceForTransports(mContext, iface,
+                            caps.getTransportTypes());
+                } catch (Exception e) {
+                    logw("Exception adding interface: " + e);
+                }
+            }
+        }
+        for (final String iface : interfaceDiff.removed) {
+            try {
+                if (DBG) log("Removing iface " + iface + " from network " + netId);
+                wakeupModifyInterface(iface, caps, false);
+                mNetd.networkRemoveInterface(netId, iface);
+            } catch (Exception e) {
+                loge("Exception removing interface: " + e);
+            }
+        }
+    }
+
+    // TODO: move to frameworks/libs/net.
+    private RouteInfoParcel convertRouteInfo(RouteInfo route) {
+        final String nextHop;
+
+        switch (route.getType()) {
+            case RouteInfo.RTN_UNICAST:
+                if (route.hasGateway()) {
+                    nextHop = route.getGateway().getHostAddress();
+                } else {
+                    nextHop = INetd.NEXTHOP_NONE;
+                }
+                break;
+            case RouteInfo.RTN_UNREACHABLE:
+                nextHop = INetd.NEXTHOP_UNREACHABLE;
+                break;
+            case RouteInfo.RTN_THROW:
+                nextHop = INetd.NEXTHOP_THROW;
+                break;
+            default:
+                nextHop = INetd.NEXTHOP_NONE;
+                break;
+        }
+
+        final RouteInfoParcel rip = new RouteInfoParcel();
+        rip.ifName = route.getInterface();
+        rip.destination = route.getDestination().toString();
+        rip.nextHop = nextHop;
+        rip.mtu = route.getMtu();
+
+        return rip;
+    }
+
+    /**
+     * Have netd update routes from oldLp to newLp.
+     * @return true if routes changed between oldLp and newLp
+     */
+    private boolean updateRoutes(LinkProperties newLp, LinkProperties oldLp, int netId) {
+        // compare the route diff to determine which routes have been updated
+        final CompareOrUpdateResult<RouteInfo.RouteKey, RouteInfo> routeDiff =
+                new CompareOrUpdateResult<>(
+                        oldLp != null ? oldLp.getAllRoutes() : null,
+                        newLp != null ? newLp.getAllRoutes() : null,
+                        (r) -> r.getRouteKey());
+
+        // add routes before removing old in case it helps with continuous connectivity
+
+        // do this twice, adding non-next-hop routes first, then routes they are dependent on
+        for (RouteInfo route : routeDiff.added) {
+            if (route.hasGateway()) continue;
+            if (VDBG || DDBG) log("Adding Route [" + route + "] to network " + netId);
+            try {
+                mNetd.networkAddRouteParcel(netId, convertRouteInfo(route));
+            } catch (Exception e) {
+                if ((route.getDestination().getAddress() instanceof Inet4Address) || VDBG) {
+                    loge("Exception in networkAddRouteParcel for non-gateway: " + e);
+                }
+            }
+        }
+        for (RouteInfo route : routeDiff.added) {
+            if (!route.hasGateway()) continue;
+            if (VDBG || DDBG) log("Adding Route [" + route + "] to network " + netId);
+            try {
+                mNetd.networkAddRouteParcel(netId, convertRouteInfo(route));
+            } catch (Exception e) {
+                if ((route.getGateway() instanceof Inet4Address) || VDBG) {
+                    loge("Exception in networkAddRouteParcel for gateway: " + e);
+                }
+            }
+        }
+
+        for (RouteInfo route : routeDiff.removed) {
+            if (VDBG || DDBG) log("Removing Route [" + route + "] from network " + netId);
+            try {
+                mNetd.networkRemoveRouteParcel(netId, convertRouteInfo(route));
+            } catch (Exception e) {
+                loge("Exception in networkRemoveRouteParcel: " + e);
+            }
+        }
+
+        for (RouteInfo route : routeDiff.updated) {
+            if (VDBG || DDBG) log("Updating Route [" + route + "] from network " + netId);
+            try {
+                mNetd.networkUpdateRouteParcel(netId, convertRouteInfo(route));
+            } catch (Exception e) {
+                loge("Exception in networkUpdateRouteParcel: " + e);
+            }
+        }
+        return !routeDiff.added.isEmpty() || !routeDiff.removed.isEmpty()
+                || !routeDiff.updated.isEmpty();
+    }
+
+    private void updateDnses(LinkProperties newLp, LinkProperties oldLp, int netId) {
+        if (oldLp != null && newLp.isIdenticalDnses(oldLp)) {
+            return;  // no updating necessary
+        }
+
+        if (DBG) {
+            final Collection<InetAddress> dnses = newLp.getDnsServers();
+            log("Setting DNS servers for network " + netId + " to " + dnses);
+        }
+        try {
+            mDnsManager.noteDnsServersForNetwork(netId, newLp);
+            mDnsManager.flushVmDnsCache();
+        } catch (Exception e) {
+            loge("Exception in setDnsConfigurationForNetwork: " + e);
+        }
+    }
+
+    private void updateVpnFiltering(LinkProperties newLp, LinkProperties oldLp,
+            NetworkAgentInfo nai) {
+        final String oldIface = oldLp != null ? oldLp.getInterfaceName() : null;
+        final String newIface = newLp != null ? newLp.getInterfaceName() : null;
+        final boolean wasFiltering = requiresVpnIsolation(nai, nai.networkCapabilities, oldLp);
+        final boolean needsFiltering = requiresVpnIsolation(nai, nai.networkCapabilities, newLp);
+
+        if (!wasFiltering && !needsFiltering) {
+            // Nothing to do.
+            return;
+        }
+
+        if (Objects.equals(oldIface, newIface) && (wasFiltering == needsFiltering)) {
+            // Nothing changed.
+            return;
+        }
+
+        final Set<UidRange> ranges = nai.networkCapabilities.getUidRanges();
+        final int vpnAppUid = nai.networkCapabilities.getOwnerUid();
+        // TODO: this create a window of opportunity for apps to receive traffic between the time
+        // when the old rules are removed and the time when new rules are added. To fix this,
+        // make eBPF support two allowlisted interfaces so here new rules can be added before the
+        // old rules are being removed.
+        if (wasFiltering) {
+            mPermissionMonitor.onVpnUidRangesRemoved(oldIface, ranges, vpnAppUid);
+        }
+        if (needsFiltering) {
+            mPermissionMonitor.onVpnUidRangesAdded(newIface, ranges, vpnAppUid);
+        }
+    }
+
+    private void updateWakeOnLan(@NonNull LinkProperties lp) {
+        if (mWolSupportedInterfaces == null) {
+            mWolSupportedInterfaces = new ArraySet<>(mResources.get().getStringArray(
+                    R.array.config_wakeonlan_supported_interfaces));
+        }
+        lp.setWakeOnLanSupported(mWolSupportedInterfaces.contains(lp.getInterfaceName()));
+    }
+
+    private int getNetworkPermission(NetworkCapabilities nc) {
+        if (!nc.hasCapability(NET_CAPABILITY_NOT_RESTRICTED)) {
+            return INetd.PERMISSION_SYSTEM;
+        }
+        if (!nc.hasCapability(NET_CAPABILITY_FOREGROUND)) {
+            return INetd.PERMISSION_NETWORK;
+        }
+        return INetd.PERMISSION_NONE;
+    }
+
+    private void updateNetworkPermissions(@NonNull final NetworkAgentInfo nai,
+            @NonNull final NetworkCapabilities newNc) {
+        final int oldPermission = getNetworkPermission(nai.networkCapabilities);
+        final int newPermission = getNetworkPermission(newNc);
+        if (oldPermission != newPermission && nai.created && !nai.isVPN()) {
+            try {
+                mNetd.networkSetPermissionForNetwork(nai.network.getNetId(), newPermission);
+            } catch (RemoteException | ServiceSpecificException e) {
+                loge("Exception in networkSetPermissionForNetwork: " + e);
+            }
+        }
+    }
+
+    /**
+     * Called when receiving NetworkCapabilities directly from a NetworkAgent.
+     * Stores into |nai| any data coming from the agent that might also be written to the network's
+     * NetworkCapabilities by ConnectivityService itself. This ensures that the data provided by the
+     * agent is not lost when updateCapabilities is called.
+     * This method should never alter the agent's NetworkCapabilities, only store data in |nai|.
+     */
+    private void processCapabilitiesFromAgent(NetworkAgentInfo nai, NetworkCapabilities nc) {
+        // Note: resetting the owner UID before storing the agent capabilities in NAI means that if
+        // the agent attempts to change the owner UID, then nai.declaredCapabilities will not
+        // actually be the same as the capabilities sent by the agent. Still, it is safer to reset
+        // the owner UID here and behave as if the agent had never tried to change it.
+        if (nai.networkCapabilities.getOwnerUid() != nc.getOwnerUid()) {
+            Log.e(TAG, nai.toShortString() + ": ignoring attempt to change owner from "
+                    + nai.networkCapabilities.getOwnerUid() + " to " + nc.getOwnerUid());
+            nc.setOwnerUid(nai.networkCapabilities.getOwnerUid());
+        }
+        nai.declaredCapabilities = new NetworkCapabilities(nc);
+    }
+
+    /** Modifies |newNc| based on the capabilities of |underlyingNetworks| and |agentCaps|. */
+    @VisibleForTesting
+    void applyUnderlyingCapabilities(@Nullable Network[] underlyingNetworks,
+            @NonNull NetworkCapabilities agentCaps, @NonNull NetworkCapabilities newNc) {
+        underlyingNetworks = underlyingNetworksOrDefault(
+                agentCaps.getOwnerUid(), underlyingNetworks);
+        long transportTypes = NetworkCapabilitiesUtils.packBits(agentCaps.getTransportTypes());
+        int downKbps = NetworkCapabilities.LINK_BANDWIDTH_UNSPECIFIED;
+        int upKbps = NetworkCapabilities.LINK_BANDWIDTH_UNSPECIFIED;
+        // metered if any underlying is metered, or originally declared metered by the agent.
+        boolean metered = !agentCaps.hasCapability(NET_CAPABILITY_NOT_METERED);
+        boolean roaming = false; // roaming if any underlying is roaming
+        boolean congested = false; // congested if any underlying is congested
+        boolean suspended = true; // suspended if all underlying are suspended
+
+        boolean hadUnderlyingNetworks = false;
+        if (null != underlyingNetworks) {
+            for (Network underlyingNetwork : underlyingNetworks) {
+                final NetworkAgentInfo underlying =
+                        getNetworkAgentInfoForNetwork(underlyingNetwork);
+                if (underlying == null) continue;
+
+                final NetworkCapabilities underlyingCaps = underlying.networkCapabilities;
+                hadUnderlyingNetworks = true;
+                for (int underlyingType : underlyingCaps.getTransportTypes()) {
+                    transportTypes |= 1L << underlyingType;
+                }
+
+                // Merge capabilities of this underlying network. For bandwidth, assume the
+                // worst case.
+                downKbps = NetworkCapabilities.minBandwidth(downKbps,
+                        underlyingCaps.getLinkDownstreamBandwidthKbps());
+                upKbps = NetworkCapabilities.minBandwidth(upKbps,
+                        underlyingCaps.getLinkUpstreamBandwidthKbps());
+                // If this underlying network is metered, the VPN is metered (it may cost money
+                // to send packets on this network).
+                metered |= !underlyingCaps.hasCapability(NET_CAPABILITY_NOT_METERED);
+                // If this underlying network is roaming, the VPN is roaming (the billing structure
+                // is different than the usual, local one).
+                roaming |= !underlyingCaps.hasCapability(NET_CAPABILITY_NOT_ROAMING);
+                // If this underlying network is congested, the VPN is congested (the current
+                // condition of the network affects the performance of this network).
+                congested |= !underlyingCaps.hasCapability(NET_CAPABILITY_NOT_CONGESTED);
+                // If this network is not suspended, the VPN is not suspended (the VPN
+                // is able to transfer some data).
+                suspended &= !underlyingCaps.hasCapability(NET_CAPABILITY_NOT_SUSPENDED);
+            }
+        }
+        if (!hadUnderlyingNetworks) {
+            // No idea what the underlying networks are; assume reasonable defaults
+            metered = true;
+            roaming = false;
+            congested = false;
+            suspended = false;
+        }
+
+        newNc.setTransportTypes(NetworkCapabilitiesUtils.unpackBits(transportTypes));
+        newNc.setLinkDownstreamBandwidthKbps(downKbps);
+        newNc.setLinkUpstreamBandwidthKbps(upKbps);
+        newNc.setCapability(NET_CAPABILITY_NOT_METERED, !metered);
+        newNc.setCapability(NET_CAPABILITY_NOT_ROAMING, !roaming);
+        newNc.setCapability(NET_CAPABILITY_NOT_CONGESTED, !congested);
+        newNc.setCapability(NET_CAPABILITY_NOT_SUSPENDED, !suspended);
+    }
+
+    /**
+     * Augments the NetworkCapabilities passed in by a NetworkAgent with capabilities that are
+     * maintained here that the NetworkAgent is not aware of (e.g., validated, captive portal,
+     * and foreground status).
+     */
+    @NonNull
+    private NetworkCapabilities mixInCapabilities(NetworkAgentInfo nai, NetworkCapabilities nc) {
+        // Once a NetworkAgent is connected, complain if some immutable capabilities are removed.
+         // Don't complain for VPNs since they're not driven by requests and there is no risk of
+         // causing a connect/teardown loop.
+         // TODO: remove this altogether and make it the responsibility of the NetworkProviders to
+         // avoid connect/teardown loops.
+        if (nai.everConnected &&
+                !nai.isVPN() &&
+                !nai.networkCapabilities.satisfiedByImmutableNetworkCapabilities(nc)) {
+            // TODO: consider not complaining when a network agent degrades its capabilities if this
+            // does not cause any request (that is not a listen) currently matching that agent to
+            // stop being matched by the updated agent.
+            String diff = nai.networkCapabilities.describeImmutableDifferences(nc);
+            if (!TextUtils.isEmpty(diff)) {
+                Log.wtf(TAG, "BUG: " + nai + " lost immutable capabilities:" + diff);
+            }
+        }
+
+        // Don't modify caller's NetworkCapabilities.
+        final NetworkCapabilities newNc = new NetworkCapabilities(nc);
+        if (nai.lastValidated) {
+            newNc.addCapability(NET_CAPABILITY_VALIDATED);
+        } else {
+            newNc.removeCapability(NET_CAPABILITY_VALIDATED);
+        }
+        if (nai.lastCaptivePortalDetected) {
+            newNc.addCapability(NET_CAPABILITY_CAPTIVE_PORTAL);
+        } else {
+            newNc.removeCapability(NET_CAPABILITY_CAPTIVE_PORTAL);
+        }
+        if (nai.isBackgroundNetwork()) {
+            newNc.removeCapability(NET_CAPABILITY_FOREGROUND);
+        } else {
+            newNc.addCapability(NET_CAPABILITY_FOREGROUND);
+        }
+        if (nai.partialConnectivity) {
+            newNc.addCapability(NET_CAPABILITY_PARTIAL_CONNECTIVITY);
+        } else {
+            newNc.removeCapability(NET_CAPABILITY_PARTIAL_CONNECTIVITY);
+        }
+        newNc.setPrivateDnsBroken(nai.networkCapabilities.isPrivateDnsBroken());
+
+        // TODO : remove this once all factories are updated to send NOT_SUSPENDED and NOT_ROAMING
+        if (!newNc.hasTransport(TRANSPORT_CELLULAR)) {
+            newNc.addCapability(NET_CAPABILITY_NOT_SUSPENDED);
+            newNc.addCapability(NET_CAPABILITY_NOT_ROAMING);
+        }
+
+        if (nai.supportsUnderlyingNetworks()) {
+            applyUnderlyingCapabilities(nai.declaredUnderlyingNetworks, nai.declaredCapabilities,
+                    newNc);
+        }
+
+        return newNc;
+    }
+
+    private void updateNetworkInfoForRoamingAndSuspended(NetworkAgentInfo nai,
+            NetworkCapabilities prevNc, NetworkCapabilities newNc) {
+        final boolean prevSuspended = !prevNc.hasCapability(NET_CAPABILITY_NOT_SUSPENDED);
+        final boolean suspended = !newNc.hasCapability(NET_CAPABILITY_NOT_SUSPENDED);
+        final boolean prevRoaming = !prevNc.hasCapability(NET_CAPABILITY_NOT_ROAMING);
+        final boolean roaming = !newNc.hasCapability(NET_CAPABILITY_NOT_ROAMING);
+        if (prevSuspended != suspended) {
+            // TODO (b/73132094) : remove this call once the few users of onSuspended and
+            // onResumed have been removed.
+            notifyNetworkCallbacks(nai, suspended ? ConnectivityManager.CALLBACK_SUSPENDED
+                    : ConnectivityManager.CALLBACK_RESUMED);
+        }
+        if (prevSuspended != suspended || prevRoaming != roaming) {
+            // updateNetworkInfo will mix in the suspended info from the capabilities and
+            // take appropriate action for the network having possibly changed state.
+            updateNetworkInfo(nai, nai.networkInfo);
+        }
+    }
+
+    /**
+     * Update the NetworkCapabilities for {@code nai} to {@code nc}. Specifically:
+     *
+     * 1. Calls mixInCapabilities to merge the passed-in NetworkCapabilities {@code nc} with the
+     *    capabilities we manage and store in {@code nai}, such as validated status and captive
+     *    portal status)
+     * 2. Takes action on the result: changes network permissions, sends CAP_CHANGED callbacks, and
+     *    potentially triggers rematches.
+     * 3. Directly informs other network stack components (NetworkStatsService, VPNs, etc. of the
+     *    change.)
+     *
+     * @param oldScore score of the network before any of the changes that prompted us
+     *                 to call this function.
+     * @param nai the network having its capabilities updated.
+     * @param nc the new network capabilities.
+     */
+    private void updateCapabilities(final int oldScore, @NonNull final NetworkAgentInfo nai,
+            @NonNull final NetworkCapabilities nc) {
+        NetworkCapabilities newNc = mixInCapabilities(nai, nc);
+        if (Objects.equals(nai.networkCapabilities, newNc)) return;
+        updateNetworkPermissions(nai, newNc);
+        final NetworkCapabilities prevNc = nai.getAndSetNetworkCapabilities(newNc);
+
+        updateUids(nai, prevNc, newNc);
+        nai.updateScoreForNetworkAgentUpdate();
+
+        if (nai.getCurrentScore() == oldScore && newNc.equalRequestableCapabilities(prevNc)) {
+            // If the requestable capabilities haven't changed, and the score hasn't changed, then
+            // the change we're processing can't affect any requests, it can only affect the listens
+            // on this network. We might have been called by rematchNetworkAndRequests when a
+            // network changed foreground state.
+            processListenRequests(nai);
+        } else {
+            // If the requestable capabilities have changed or the score changed, we can't have been
+            // called by rematchNetworkAndRequests, so it's safe to start a rematch.
+            rematchAllNetworksAndRequests();
+            notifyNetworkCallbacks(nai, ConnectivityManager.CALLBACK_CAP_CHANGED);
+        }
+        updateNetworkInfoForRoamingAndSuspended(nai, prevNc, newNc);
+
+        final boolean oldMetered = prevNc.isMetered();
+        final boolean newMetered = newNc.isMetered();
+        final boolean meteredChanged = oldMetered != newMetered;
+
+        if (meteredChanged) {
+            maybeNotifyNetworkBlocked(nai, oldMetered, newMetered,
+                    mVpnBlockedUidRanges, mVpnBlockedUidRanges);
+        }
+
+        final boolean roamingChanged = prevNc.hasCapability(NET_CAPABILITY_NOT_ROAMING)
+                != newNc.hasCapability(NET_CAPABILITY_NOT_ROAMING);
+
+        // Report changes that are interesting for network statistics tracking.
+        if (meteredChanged || roamingChanged) {
+            notifyIfacesChangedForNetworkStats();
+        }
+
+        // This network might have been underlying another network. Propagate its capabilities.
+        propagateUnderlyingNetworkCapabilities(nai.network);
+
+        if (!newNc.equalsTransportTypes(prevNc)) {
+            mDnsManager.updateTransportsForNetwork(
+                    nai.network.getNetId(), newNc.getTransportTypes());
+        }
+    }
+
+    /** Convenience method to update the capabilities for a given network. */
+    private void updateCapabilitiesForNetwork(NetworkAgentInfo nai) {
+        updateCapabilities(nai.getCurrentScore(), nai, nai.networkCapabilities);
+    }
+
+    /**
+     * Returns whether VPN isolation (ingress interface filtering) should be applied on the given
+     * network.
+     *
+     * Ingress interface filtering enforces that all apps under the given network can only receive
+     * packets from the network's interface (and loopback). This is important for VPNs because
+     * apps that cannot bypass a fully-routed VPN shouldn't be able to receive packets from any
+     * non-VPN interfaces.
+     *
+     * As a result, this method should return true iff
+     *  1. the network is an app VPN (not legacy VPN)
+     *  2. the VPN does not allow bypass
+     *  3. the VPN is fully-routed
+     *  4. the VPN interface is non-null
+     *
+     * @see INetd#firewallAddUidInterfaceRules
+     * @see INetd#firewallRemoveUidInterfaceRules
+     */
+    private boolean requiresVpnIsolation(@NonNull NetworkAgentInfo nai, NetworkCapabilities nc,
+            LinkProperties lp) {
+        if (nc == null || lp == null) return false;
+        return nai.isVPN()
+                && !nai.networkAgentConfig.allowBypass
+                && nc.getOwnerUid() != Process.SYSTEM_UID
+                && lp.getInterfaceName() != null
+                && (lp.hasIpv4DefaultRoute() || lp.hasIpv4UnreachableDefaultRoute())
+                && (lp.hasIpv6DefaultRoute() || lp.hasIpv6UnreachableDefaultRoute());
+    }
+
+    private static UidRangeParcel[] toUidRangeStableParcels(final @NonNull Set<UidRange> ranges) {
+        final UidRangeParcel[] stableRanges = new UidRangeParcel[ranges.size()];
+        int index = 0;
+        for (UidRange range : ranges) {
+            stableRanges[index] = new UidRangeParcel(range.start, range.stop);
+            index++;
+        }
+        return stableRanges;
+    }
+
+    private static UidRangeParcel[] toUidRangeStableParcels(UidRange[] ranges) {
+        final UidRangeParcel[] stableRanges = new UidRangeParcel[ranges.length];
+        for (int i = 0; i < ranges.length; i++) {
+            stableRanges[i] = new UidRangeParcel(ranges[i].start, ranges[i].stop);
+        }
+        return stableRanges;
+    }
+
+    private void maybeCloseSockets(NetworkAgentInfo nai, UidRangeParcel[] ranges,
+            int[] exemptUids) {
+        if (nai.isVPN() && !nai.networkAgentConfig.allowBypass) {
+            try {
+                mNetd.socketDestroy(ranges, exemptUids);
+            } catch (Exception e) {
+                loge("Exception in socket destroy: ", e);
+            }
+        }
+    }
+
+    private void updateUidRanges(boolean add, NetworkAgentInfo nai, Set<UidRange> uidRanges) {
+        int[] exemptUids = new int[2];
+        // TODO: Excluding VPN_UID is necessary in order to not to kill the TCP connection used
+        // by PPTP. Fix this by making Vpn set the owner UID to VPN_UID instead of system when
+        // starting a legacy VPN, and remove VPN_UID here. (b/176542831)
+        exemptUids[0] = VPN_UID;
+        exemptUids[1] = nai.networkCapabilities.getOwnerUid();
+        UidRangeParcel[] ranges = toUidRangeStableParcels(uidRanges);
+
+        maybeCloseSockets(nai, ranges, exemptUids);
+        try {
+            if (add) {
+                mNetd.networkAddUidRanges(nai.network.netId, ranges);
+            } else {
+                mNetd.networkRemoveUidRanges(nai.network.netId, ranges);
+            }
+        } catch (Exception e) {
+            loge("Exception while " + (add ? "adding" : "removing") + " uid ranges " + uidRanges +
+                    " on netId " + nai.network.netId + ". " + e);
+        }
+        maybeCloseSockets(nai, ranges, exemptUids);
+    }
+
+    private void updateUids(NetworkAgentInfo nai, NetworkCapabilities prevNc,
+            NetworkCapabilities newNc) {
+        Set<UidRange> prevRanges = null == prevNc ? null : prevNc.getUidRanges();
+        Set<UidRange> newRanges = null == newNc ? null : newNc.getUidRanges();
+        if (null == prevRanges) prevRanges = new ArraySet<>();
+        if (null == newRanges) newRanges = new ArraySet<>();
+        final Set<UidRange> prevRangesCopy = new ArraySet<>(prevRanges);
+
+        prevRanges.removeAll(newRanges);
+        newRanges.removeAll(prevRangesCopy);
+
+        try {
+            // When updating the VPN uid routing rules, add the new range first then remove the old
+            // range. If old range were removed first, there would be a window between the old
+            // range being removed and the new range being added, during which UIDs contained
+            // in both ranges are not subject to any VPN routing rules. Adding new range before
+            // removing old range works because, unlike the filtering rules below, it's possible to
+            // add duplicate UID routing rules.
+            // TODO: calculate the intersection of add & remove. Imagining that we are trying to
+            // remove uid 3 from a set containing 1-5. Intersection of the prev and new sets is:
+            //   [1-5] & [1-2],[4-5] == [3]
+            // Then we can do:
+            //   maybeCloseSockets([3])
+            //   mNetd.networkAddUidRanges([1-2],[4-5])
+            //   mNetd.networkRemoveUidRanges([1-5])
+            //   maybeCloseSockets([3])
+            // This can prevent the sockets of uid 1-2, 4-5 from being closed. It also reduce the
+            // number of binder calls from 6 to 4.
+            if (!newRanges.isEmpty()) {
+                updateUidRanges(true, nai, newRanges);
+            }
+            if (!prevRanges.isEmpty()) {
+                updateUidRanges(false, nai, prevRanges);
+            }
+            final boolean wasFiltering = requiresVpnIsolation(nai, prevNc, nai.linkProperties);
+            final boolean shouldFilter = requiresVpnIsolation(nai, newNc, nai.linkProperties);
+            final String iface = nai.linkProperties.getInterfaceName();
+            // For VPN uid interface filtering, old ranges need to be removed before new ranges can
+            // be added, due to the range being expanded and stored as individual UIDs. For example
+            // the UIDs might be updated from [0, 99999] to ([0, 10012], [10014, 99999]) which means
+            // prevRanges = [0, 99999] while newRanges = [0, 10012], [10014, 99999]. If prevRanges
+            // were added first and then newRanges got removed later, there would be only one uid
+            // 10013 left. A consequence of removing old ranges before adding new ranges is that
+            // there is now a window of opportunity when the UIDs are not subject to any filtering.
+            // Note that this is in contrast with the (more robust) update of VPN routing rules
+            // above, where the addition of new ranges happens before the removal of old ranges.
+            // TODO Fix this window by computing an accurate diff on Set<UidRange>, so the old range
+            // to be removed will never overlap with the new range to be added.
+            if (wasFiltering && !prevRanges.isEmpty()) {
+                mPermissionMonitor.onVpnUidRangesRemoved(iface, prevRanges, prevNc.getOwnerUid());
+            }
+            if (shouldFilter && !newRanges.isEmpty()) {
+                mPermissionMonitor.onVpnUidRangesAdded(iface, newRanges, newNc.getOwnerUid());
+            }
+        } catch (Exception e) {
+            // Never crash!
+            loge("Exception in updateUids: ", e);
+        }
+    }
+
+    public void handleUpdateLinkProperties(NetworkAgentInfo nai, LinkProperties newLp) {
+        ensureRunningOnConnectivityServiceThread();
+
+        if (getNetworkAgentInfoForNetId(nai.network.getNetId()) != nai) {
+            // Ignore updates for disconnected networks
+            return;
+        }
+        if (VDBG || DDBG) {
+            log("Update of LinkProperties for " + nai.toShortString()
+                    + "; created=" + nai.created
+                    + "; everConnected=" + nai.everConnected);
+        }
+        // TODO: eliminate this defensive copy after confirming that updateLinkProperties does not
+        // modify its oldLp parameter.
+        updateLinkProperties(nai, newLp, new LinkProperties(nai.linkProperties));
+    }
+
+    private void sendPendingIntentForRequest(NetworkRequestInfo nri, NetworkAgentInfo networkAgent,
+            int notificationType) {
+        if (notificationType == ConnectivityManager.CALLBACK_AVAILABLE && !nri.mPendingIntentSent) {
+            Intent intent = new Intent();
+            intent.putExtra(ConnectivityManager.EXTRA_NETWORK, networkAgent.network);
+            // If apps could file multi-layer requests with PendingIntents, they'd need to know
+            // which of the layer is satisfied alongside with some ID for the request. Hence, if
+            // such an API is ever implemented, there is no doubt the right request to send in
+            // EXTRA_NETWORK_REQUEST is mActiveRequest, and whatever ID would be added would need to
+            // be sent as a separate extra.
+            intent.putExtra(ConnectivityManager.EXTRA_NETWORK_REQUEST, nri.getActiveRequest());
+            nri.mPendingIntentSent = true;
+            sendIntent(nri.mPendingIntent, intent);
+        }
+        // else not handled
+    }
+
+    private void sendIntent(PendingIntent pendingIntent, Intent intent) {
+        mPendingIntentWakeLock.acquire();
+        try {
+            if (DBG) log("Sending " + pendingIntent);
+            pendingIntent.send(mContext, 0, intent, this /* onFinished */, null /* Handler */);
+        } catch (PendingIntent.CanceledException e) {
+            if (DBG) log(pendingIntent + " was not sent, it had been canceled.");
+            mPendingIntentWakeLock.release();
+            releasePendingNetworkRequest(pendingIntent);
+        }
+        // ...otherwise, mPendingIntentWakeLock.release() gets called by onSendFinished()
+    }
+
+    @Override
+    public void onSendFinished(PendingIntent pendingIntent, Intent intent, int resultCode,
+            String resultData, Bundle resultExtras) {
+        if (DBG) log("Finished sending " + pendingIntent);
+        mPendingIntentWakeLock.release();
+        // Release with a delay so the receiving client has an opportunity to put in its
+        // own request.
+        releasePendingNetworkRequestWithDelay(pendingIntent);
+    }
+
+    private void callCallbackForRequest(@NonNull final NetworkRequestInfo nri,
+            @NonNull final NetworkAgentInfo networkAgent, final int notificationType,
+            final int arg1) {
+        if (nri.mMessenger == null) {
+            // Default request has no msgr. Also prevents callbacks from being invoked for
+            // NetworkRequestInfos registered with ConnectivityDiagnostics requests. Those callbacks
+            // are Type.LISTEN, but should not have NetworkCallbacks invoked.
+            return;
+        }
+        Bundle bundle = new Bundle();
+        // TODO b/177608132: make sure callbacks are indexed by NRIs and not NetworkRequest objects.
+        // TODO: check if defensive copies of data is needed.
+        final NetworkRequest nrForCallback = nri.getNetworkRequestForCallback();
+        putParcelable(bundle, nrForCallback);
+        Message msg = Message.obtain();
+        if (notificationType != ConnectivityManager.CALLBACK_UNAVAIL) {
+            putParcelable(bundle, networkAgent.network);
+        }
+        final boolean includeLocationSensitiveInfo =
+                (nri.mCallbackFlags & NetworkCallback.FLAG_INCLUDE_LOCATION_INFO) != 0;
+        switch (notificationType) {
+            case ConnectivityManager.CALLBACK_AVAILABLE: {
+                final NetworkCapabilities nc =
+                        networkCapabilitiesRestrictedForCallerPermissions(
+                                networkAgent.networkCapabilities, nri.mPid, nri.mUid);
+                putParcelable(
+                        bundle,
+                        createWithLocationInfoSanitizedIfNecessaryWhenParceled(
+                                nc, includeLocationSensitiveInfo, nri.mPid, nri.mUid,
+                                nrForCallback.getRequestorPackageName(),
+                                nri.mCallingAttributionTag));
+                putParcelable(bundle, linkPropertiesRestrictedForCallerPermissions(
+                        networkAgent.linkProperties, nri.mPid, nri.mUid));
+                // For this notification, arg1 contains the blocked status.
+                msg.arg1 = arg1;
+                break;
+            }
+            case ConnectivityManager.CALLBACK_LOSING: {
+                msg.arg1 = arg1;
+                break;
+            }
+            case ConnectivityManager.CALLBACK_CAP_CHANGED: {
+                // networkAgent can't be null as it has been accessed a few lines above.
+                final NetworkCapabilities netCap =
+                        networkCapabilitiesRestrictedForCallerPermissions(
+                                networkAgent.networkCapabilities, nri.mPid, nri.mUid);
+                putParcelable(
+                        bundle,
+                        createWithLocationInfoSanitizedIfNecessaryWhenParceled(
+                                netCap, includeLocationSensitiveInfo, nri.mPid, nri.mUid,
+                                nrForCallback.getRequestorPackageName(),
+                                nri.mCallingAttributionTag));
+                break;
+            }
+            case ConnectivityManager.CALLBACK_IP_CHANGED: {
+                putParcelable(bundle, linkPropertiesRestrictedForCallerPermissions(
+                        networkAgent.linkProperties, nri.mPid, nri.mUid));
+                break;
+            }
+            case ConnectivityManager.CALLBACK_BLK_CHANGED: {
+                maybeLogBlockedStatusChanged(nri, networkAgent.network, arg1);
+                msg.arg1 = arg1;
+                break;
+            }
+        }
+        msg.what = notificationType;
+        msg.setData(bundle);
+        try {
+            if (VDBG) {
+                String notification = ConnectivityManager.getCallbackName(notificationType);
+                log("sending notification " + notification + " for " + nrForCallback);
+            }
+            nri.mMessenger.send(msg);
+        } catch (RemoteException e) {
+            // may occur naturally in the race of binder death.
+            loge("RemoteException caught trying to send a callback msg for " + nrForCallback);
+        }
+    }
+
+    private static <T extends Parcelable> void putParcelable(Bundle bundle, T t) {
+        bundle.putParcelable(t.getClass().getSimpleName(), t);
+    }
+
+    private void teardownUnneededNetwork(NetworkAgentInfo nai) {
+        if (nai.numRequestNetworkRequests() != 0) {
+            for (int i = 0; i < nai.numNetworkRequests(); i++) {
+                NetworkRequest nr = nai.requestAt(i);
+                // Ignore listening and track default requests.
+                if (!nr.isRequest()) continue;
+                loge("Dead network still had at least " + nr);
+                break;
+            }
+        }
+        nai.disconnect();
+    }
+
+    private void handleLingerComplete(NetworkAgentInfo oldNetwork) {
+        if (oldNetwork == null) {
+            loge("Unknown NetworkAgentInfo in handleLingerComplete");
+            return;
+        }
+        if (DBG) log("handleLingerComplete for " + oldNetwork.toShortString());
+
+        // If we get here it means that the last linger timeout for this network expired. So there
+        // must be no other active linger timers, and we must stop lingering.
+        oldNetwork.clearInactivityState();
+
+        if (unneeded(oldNetwork, UnneededFor.TEARDOWN)) {
+            // Tear the network down.
+            teardownUnneededNetwork(oldNetwork);
+        } else {
+            // Put the network in the background if it doesn't satisfy any foreground request.
+            updateCapabilitiesForNetwork(oldNetwork);
+        }
+    }
+
+    private void processDefaultNetworkChanges(@NonNull final NetworkReassignment changes) {
+        boolean isDefaultChanged = false;
+        for (final NetworkRequestInfo defaultRequestInfo : mDefaultNetworkRequests) {
+            final NetworkReassignment.RequestReassignment reassignment =
+                    changes.getReassignment(defaultRequestInfo);
+            if (null == reassignment) {
+                continue;
+            }
+            // reassignment only contains those instances where the satisfying network changed.
+            isDefaultChanged = true;
+            // Notify system services of the new default.
+            makeDefault(defaultRequestInfo, reassignment.mOldNetwork, reassignment.mNewNetwork);
+        }
+
+        if (isDefaultChanged) {
+            // Hold a wakelock for a short time to help apps in migrating to a new default.
+            scheduleReleaseNetworkTransitionWakelock();
+        }
+    }
+
+    private void makeDefault(@NonNull final NetworkRequestInfo nri,
+            @Nullable final NetworkAgentInfo oldDefaultNetwork,
+            @Nullable final NetworkAgentInfo newDefaultNetwork) {
+        if (DBG) {
+            log("Switching to new default network for: " + nri + " using " + newDefaultNetwork);
+        }
+
+        // Fix up the NetworkCapabilities of any networks that have this network as underlying.
+        if (newDefaultNetwork != null) {
+            propagateUnderlyingNetworkCapabilities(newDefaultNetwork.network);
+        }
+
+        // Set an app level managed default and return since further processing only applies to the
+        // default network.
+        if (mDefaultRequest != nri) {
+            makeDefaultForApps(nri, oldDefaultNetwork, newDefaultNetwork);
+            return;
+        }
+
+        makeDefaultNetwork(newDefaultNetwork);
+
+        if (oldDefaultNetwork != null) {
+            mLingerMonitor.noteLingerDefaultNetwork(oldDefaultNetwork, newDefaultNetwork);
+        }
+        mNetworkActivityTracker.updateDataActivityTracking(newDefaultNetwork, oldDefaultNetwork);
+        handleApplyDefaultProxy(null != newDefaultNetwork
+                ? newDefaultNetwork.linkProperties.getHttpProxy() : null);
+        updateTcpBufferSizes(null != newDefaultNetwork
+                ? newDefaultNetwork.linkProperties.getTcpBufferSizes() : null);
+        notifyIfacesChangedForNetworkStats();
+    }
+
+    private void makeDefaultForApps(@NonNull final NetworkRequestInfo nri,
+            @Nullable final NetworkAgentInfo oldDefaultNetwork,
+            @Nullable final NetworkAgentInfo newDefaultNetwork) {
+        try {
+            if (VDBG) {
+                log("Setting default network for " + nri
+                        + " using UIDs " + nri.getUids()
+                        + " with old network " + (oldDefaultNetwork != null
+                        ? oldDefaultNetwork.network().getNetId() : "null")
+                        + " and new network " + (newDefaultNetwork != null
+                        ? newDefaultNetwork.network().getNetId() : "null"));
+            }
+            if (nri.getUids().isEmpty()) {
+                throw new IllegalStateException("makeDefaultForApps called without specifying"
+                        + " any applications to set as the default." + nri);
+            }
+            if (null != newDefaultNetwork) {
+                mNetd.networkAddUidRanges(
+                        newDefaultNetwork.network.getNetId(),
+                        toUidRangeStableParcels(nri.getUids()));
+            }
+            if (null != oldDefaultNetwork) {
+                mNetd.networkRemoveUidRanges(
+                        oldDefaultNetwork.network.getNetId(),
+                        toUidRangeStableParcels(nri.getUids()));
+            }
+        } catch (RemoteException | ServiceSpecificException e) {
+            loge("Exception setting app default network", e);
+        }
+    }
+
+    private void makeDefaultNetwork(@Nullable final NetworkAgentInfo newDefaultNetwork) {
+        try {
+            if (null != newDefaultNetwork) {
+                mNetd.networkSetDefault(newDefaultNetwork.network.getNetId());
+            } else {
+                mNetd.networkClearDefault();
+            }
+        } catch (RemoteException | ServiceSpecificException e) {
+            loge("Exception setting default network :" + e);
+        }
+    }
+
+    private void processListenRequests(@NonNull final NetworkAgentInfo nai) {
+        // For consistency with previous behaviour, send onLost callbacks before onAvailable.
+        processNewlyLostListenRequests(nai);
+        notifyNetworkCallbacks(nai, ConnectivityManager.CALLBACK_CAP_CHANGED);
+        processNewlySatisfiedListenRequests(nai);
+    }
+
+    private void processNewlyLostListenRequests(@NonNull final NetworkAgentInfo nai) {
+        for (final NetworkRequestInfo nri : mNetworkRequests.values()) {
+            if (nri.isMultilayerRequest()) {
+                continue;
+            }
+            final NetworkRequest nr = nri.mRequests.get(0);
+            if (!nr.isListen()) continue;
+            if (nai.isSatisfyingRequest(nr.requestId) && !nai.satisfies(nr)) {
+                nai.removeRequest(nr.requestId);
+                callCallbackForRequest(nri, nai, ConnectivityManager.CALLBACK_LOST, 0);
+            }
+        }
+    }
+
+    private void processNewlySatisfiedListenRequests(@NonNull final NetworkAgentInfo nai) {
+        for (final NetworkRequestInfo nri : mNetworkRequests.values()) {
+            if (nri.isMultilayerRequest()) {
+                continue;
+            }
+            final NetworkRequest nr = nri.mRequests.get(0);
+            if (!nr.isListen()) continue;
+            if (nai.satisfies(nr) && !nai.isSatisfyingRequest(nr.requestId)) {
+                nai.addRequest(nr);
+                notifyNetworkAvailable(nai, nri);
+            }
+        }
+    }
+
+    // An accumulator class to gather the list of changes that result from a rematch.
+    private static class NetworkReassignment {
+        static class RequestReassignment {
+            @NonNull public final NetworkRequestInfo mNetworkRequestInfo;
+            @Nullable public final NetworkRequest mOldNetworkRequest;
+            @Nullable public final NetworkRequest mNewNetworkRequest;
+            @Nullable public final NetworkAgentInfo mOldNetwork;
+            @Nullable public final NetworkAgentInfo mNewNetwork;
+            RequestReassignment(@NonNull final NetworkRequestInfo networkRequestInfo,
+                    @Nullable final NetworkRequest oldNetworkRequest,
+                    @Nullable final NetworkRequest newNetworkRequest,
+                    @Nullable final NetworkAgentInfo oldNetwork,
+                    @Nullable final NetworkAgentInfo newNetwork) {
+                mNetworkRequestInfo = networkRequestInfo;
+                mOldNetworkRequest = oldNetworkRequest;
+                mNewNetworkRequest = newNetworkRequest;
+                mOldNetwork = oldNetwork;
+                mNewNetwork = newNetwork;
+            }
+
+            public String toString() {
+                final NetworkRequest requestToShow = null != mNewNetworkRequest
+                        ? mNewNetworkRequest : mNetworkRequestInfo.mRequests.get(0);
+                return requestToShow.requestId + " : "
+                        + (null != mOldNetwork ? mOldNetwork.network.getNetId() : "null")
+                        + " → " + (null != mNewNetwork ? mNewNetwork.network.getNetId() : "null");
+            }
+        }
+
+        @NonNull private final ArrayList<RequestReassignment> mReassignments = new ArrayList<>();
+
+        @NonNull Iterable<RequestReassignment> getRequestReassignments() {
+            return mReassignments;
+        }
+
+        void addRequestReassignment(@NonNull final RequestReassignment reassignment) {
+            if (Build.isDebuggable()) {
+                // The code is never supposed to add two reassignments of the same request. Make
+                // sure this stays true, but without imposing this expensive check on all
+                // reassignments on all user devices.
+                for (final RequestReassignment existing : mReassignments) {
+                    if (existing.mNetworkRequestInfo.equals(reassignment.mNetworkRequestInfo)) {
+                        throw new IllegalStateException("Trying to reassign ["
+                                + reassignment + "] but already have ["
+                                + existing + "]");
+                    }
+                }
+            }
+            mReassignments.add(reassignment);
+        }
+
+        // Will return null if this reassignment does not change the network assigned to
+        // the passed request.
+        @Nullable
+        private RequestReassignment getReassignment(@NonNull final NetworkRequestInfo nri) {
+            for (final RequestReassignment event : getRequestReassignments()) {
+                if (nri == event.mNetworkRequestInfo) return event;
+            }
+            return null;
+        }
+
+        public String toString() {
+            final StringJoiner sj = new StringJoiner(", " /* delimiter */,
+                    "NetReassign [" /* prefix */, "]" /* suffix */);
+            if (mReassignments.isEmpty()) return sj.add("no changes").toString();
+            for (final RequestReassignment rr : getRequestReassignments()) {
+                sj.add(rr.toString());
+            }
+            return sj.toString();
+        }
+
+        public String debugString() {
+            final StringBuilder sb = new StringBuilder();
+            sb.append("NetworkReassignment :");
+            if (mReassignments.isEmpty()) return sb.append(" no changes").toString();
+            for (final RequestReassignment rr : getRequestReassignments()) {
+                sb.append("\n  ").append(rr);
+            }
+            return sb.append("\n").toString();
+        }
+    }
+
+    private void updateSatisfiersForRematchRequest(@NonNull final NetworkRequestInfo nri,
+            @Nullable final NetworkRequest previousRequest,
+            @Nullable final NetworkRequest newRequest,
+            @Nullable final NetworkAgentInfo previousSatisfier,
+            @Nullable final NetworkAgentInfo newSatisfier,
+            final long now) {
+        if (null != newSatisfier && mNoServiceNetwork != newSatisfier) {
+            if (VDBG) log("rematch for " + newSatisfier.toShortString());
+            if (null != previousRequest && null != previousSatisfier) {
+                if (VDBG || DDBG) {
+                    log("   accepting network in place of " + previousSatisfier.toShortString());
+                }
+                previousSatisfier.removeRequest(previousRequest.requestId);
+                previousSatisfier.lingerRequest(previousRequest.requestId, now);
+            } else {
+                if (VDBG || DDBG) log("   accepting network in place of null");
+            }
+
+            // To prevent constantly CPU wake up for nascent timer, if a network comes up
+            // and immediately satisfies a request then remove the timer. This will happen for
+            // all networks except in the case of an underlying network for a VCN.
+            if (newSatisfier.isNascent()) {
+                newSatisfier.unlingerRequest(NetworkRequest.REQUEST_ID_NONE);
+                newSatisfier.unsetInactive();
+            }
+
+            // if newSatisfier is not null, then newRequest may not be null.
+            newSatisfier.unlingerRequest(newRequest.requestId);
+            if (!newSatisfier.addRequest(newRequest)) {
+                Log.wtf(TAG, "BUG: " + newSatisfier.toShortString() + " already has "
+                        + newRequest);
+            }
+        } else if (null != previousRequest && null != previousSatisfier) {
+            if (DBG) {
+                log("Network " + previousSatisfier.toShortString() + " stopped satisfying"
+                        + " request " + previousRequest.requestId);
+            }
+            previousSatisfier.removeRequest(previousRequest.requestId);
+        }
+        nri.setSatisfier(newSatisfier, newRequest);
+    }
+
+    /**
+     * This function is triggered when something can affect what network should satisfy what
+     * request, and it computes the network reassignment from the passed collection of requests to
+     * network match to the one that the system should now have. That data is encoded in an
+     * object that is a list of changes, each of them having an NRI, and old satisfier, and a new
+     * satisfier.
+     *
+     * After the reassignment is computed, it is applied to the state objects.
+     *
+     * @param networkRequests the nri objects to evaluate for possible network reassignment
+     * @return NetworkReassignment listing of proposed network assignment changes
+     */
+    @NonNull
+    private NetworkReassignment computeNetworkReassignment(
+            @NonNull final Collection<NetworkRequestInfo> networkRequests) {
+        final NetworkReassignment changes = new NetworkReassignment();
+
+        // Gather the list of all relevant agents.
+        final ArrayList<NetworkAgentInfo> nais = new ArrayList<>();
+        for (final NetworkAgentInfo nai : mNetworkAgentInfos) {
+            if (!nai.everConnected) {
+                continue;
+            }
+            nais.add(nai);
+        }
+
+        for (final NetworkRequestInfo nri : networkRequests) {
+            // Non-multilayer listen requests can be ignored.
+            if (!nri.isMultilayerRequest() && nri.mRequests.get(0).isListen()) {
+                continue;
+            }
+            NetworkAgentInfo bestNetwork = null;
+            NetworkRequest bestRequest = null;
+            for (final NetworkRequest req : nri.mRequests) {
+                bestNetwork = mNetworkRanker.getBestNetwork(req, nais, nri.getSatisfier());
+                // Stop evaluating as the highest possible priority request is satisfied.
+                if (null != bestNetwork) {
+                    bestRequest = req;
+                    break;
+                }
+            }
+            if (null == bestNetwork && isDefaultBlocked(nri)) {
+                // Remove default networking if disallowed for managed default requests.
+                bestNetwork = mNoServiceNetwork;
+            }
+            if (nri.getSatisfier() != bestNetwork) {
+                // bestNetwork may be null if no network can satisfy this request.
+                changes.addRequestReassignment(new NetworkReassignment.RequestReassignment(
+                        nri, nri.mActiveRequest, bestRequest, nri.getSatisfier(), bestNetwork));
+            }
+        }
+        return changes;
+    }
+
+    private Set<NetworkRequestInfo> getNrisFromGlobalRequests() {
+        return new HashSet<>(mNetworkRequests.values());
+    }
+
+    /**
+     * Attempt to rematch all Networks with all NetworkRequests.  This may result in Networks
+     * being disconnected.
+     */
+    private void rematchAllNetworksAndRequests() {
+        rematchNetworksAndRequests(getNrisFromGlobalRequests());
+    }
+
+    /**
+     * Attempt to rematch all Networks with given NetworkRequests.  This may result in Networks
+     * being disconnected.
+     */
+    private void rematchNetworksAndRequests(
+            @NonNull final Set<NetworkRequestInfo> networkRequests) {
+        ensureRunningOnConnectivityServiceThread();
+        // TODO: This may be slow, and should be optimized.
+        final long now = SystemClock.elapsedRealtime();
+        final NetworkReassignment changes = computeNetworkReassignment(networkRequests);
+        if (VDBG || DDBG) {
+            log(changes.debugString());
+        } else if (DBG) {
+            log(changes.toString()); // Shorter form, only one line of log
+        }
+        applyNetworkReassignment(changes, now);
+        issueNetworkNeeds();
+    }
+
+    private void applyNetworkReassignment(@NonNull final NetworkReassignment changes,
+            final long now) {
+        final Collection<NetworkAgentInfo> nais = mNetworkAgentInfos;
+
+        // Since most of the time there are only 0 or 1 background networks, it would probably
+        // be more efficient to just use an ArrayList here. TODO : measure performance
+        final ArraySet<NetworkAgentInfo> oldBgNetworks = new ArraySet<>();
+        for (final NetworkAgentInfo nai : nais) {
+            if (nai.isBackgroundNetwork()) oldBgNetworks.add(nai);
+        }
+
+        // First, update the lists of satisfied requests in the network agents. This is necessary
+        // because some code later depends on this state to be correct, most prominently computing
+        // the linger status.
+        for (final NetworkReassignment.RequestReassignment event :
+                changes.getRequestReassignments()) {
+            updateSatisfiersForRematchRequest(event.mNetworkRequestInfo,
+                    event.mOldNetworkRequest, event.mNewNetworkRequest,
+                    event.mOldNetwork, event.mNewNetwork,
+                    now);
+        }
+
+        // Process default network changes if applicable.
+        processDefaultNetworkChanges(changes);
+
+        // Notify requested networks are available after the default net is switched, but
+        // before LegacyTypeTracker sends legacy broadcasts
+        for (final NetworkReassignment.RequestReassignment event :
+                changes.getRequestReassignments()) {
+            if (null != event.mNewNetwork) {
+                notifyNetworkAvailable(event.mNewNetwork, event.mNetworkRequestInfo);
+            } else {
+                callCallbackForRequest(event.mNetworkRequestInfo, event.mOldNetwork,
+                        ConnectivityManager.CALLBACK_LOST, 0);
+            }
+        }
+
+        // Update the inactivity state before processing listen callbacks, because the background
+        // computation depends on whether the network is inactive. Don't send the LOSING callbacks
+        // just yet though, because they have to be sent after the listens are processed to keep
+        // backward compatibility.
+        final ArrayList<NetworkAgentInfo> inactiveNetworks = new ArrayList<>();
+        for (final NetworkAgentInfo nai : nais) {
+            // Rematching may have altered the inactivity state of some networks, so update all
+            // inactivity timers. updateInactivityState reads the state from the network agent
+            // and does nothing if the state has not changed : the source of truth is controlled
+            // with NetworkAgentInfo#lingerRequest and NetworkAgentInfo#unlingerRequest, which
+            // have been called while rematching the individual networks above.
+            if (updateInactivityState(nai, now)) {
+                inactiveNetworks.add(nai);
+            }
+        }
+
+        for (final NetworkAgentInfo nai : nais) {
+            if (!nai.everConnected) continue;
+            final boolean oldBackground = oldBgNetworks.contains(nai);
+            // Process listen requests and update capabilities if the background state has
+            // changed for this network. For consistency with previous behavior, send onLost
+            // callbacks before onAvailable.
+            processNewlyLostListenRequests(nai);
+            if (oldBackground != nai.isBackgroundNetwork()) {
+                applyBackgroundChangeForRematch(nai);
+            }
+            processNewlySatisfiedListenRequests(nai);
+        }
+
+        for (final NetworkAgentInfo nai : inactiveNetworks) {
+            // For nascent networks, if connecting with no foreground request, skip broadcasting
+            // LOSING for backward compatibility. This is typical when mobile data connected while
+            // wifi connected with mobile data always-on enabled.
+            if (nai.isNascent()) continue;
+            notifyNetworkLosing(nai, now);
+        }
+
+        updateLegacyTypeTrackerAndVpnLockdownForRematch(changes, nais);
+
+        // Tear down all unneeded networks.
+        for (NetworkAgentInfo nai : mNetworkAgentInfos) {
+            if (unneeded(nai, UnneededFor.TEARDOWN)) {
+                if (nai.getInactivityExpiry() > 0) {
+                    // This network has active linger timers and no requests, but is not
+                    // lingering. Linger it.
+                    //
+                    // One way (the only way?) this can happen if this network is unvalidated
+                    // and became unneeded due to another network improving its score to the
+                    // point where this network will no longer be able to satisfy any requests
+                    // even if it validates.
+                    if (updateInactivityState(nai, now)) {
+                        notifyNetworkLosing(nai, now);
+                    }
+                } else {
+                    if (DBG) log("Reaping " + nai.toShortString());
+                    teardownUnneededNetwork(nai);
+                }
+            }
+        }
+    }
+
+    /**
+     * Apply a change in background state resulting from rematching networks with requests.
+     *
+     * During rematch, a network may change background states by starting to satisfy or stopping
+     * to satisfy a foreground request. Listens don't count for this. When a network changes
+     * background states, its capabilities need to be updated and callbacks fired for the
+     * capability change.
+     *
+     * @param nai The network that changed background states
+     */
+    private void applyBackgroundChangeForRematch(@NonNull final NetworkAgentInfo nai) {
+        final NetworkCapabilities newNc = mixInCapabilities(nai, nai.networkCapabilities);
+        if (Objects.equals(nai.networkCapabilities, newNc)) return;
+        updateNetworkPermissions(nai, newNc);
+        nai.getAndSetNetworkCapabilities(newNc);
+        notifyNetworkCallbacks(nai, ConnectivityManager.CALLBACK_CAP_CHANGED);
+    }
+
+    private void updateLegacyTypeTrackerAndVpnLockdownForRematch(
+            @NonNull final NetworkReassignment changes,
+            @NonNull final Collection<NetworkAgentInfo> nais) {
+        final NetworkReassignment.RequestReassignment reassignmentOfDefault =
+                changes.getReassignment(mDefaultRequest);
+        final NetworkAgentInfo oldDefaultNetwork =
+                null != reassignmentOfDefault ? reassignmentOfDefault.mOldNetwork : null;
+        final NetworkAgentInfo newDefaultNetwork =
+                null != reassignmentOfDefault ? reassignmentOfDefault.mNewNetwork : null;
+
+        if (oldDefaultNetwork != newDefaultNetwork) {
+            // Maintain the illusion : since the legacy API only understands one network at a time,
+            // if the default network changed, apps should see a disconnected broadcast for the
+            // old default network before they see a connected broadcast for the new one.
+            if (oldDefaultNetwork != null) {
+                mLegacyTypeTracker.remove(oldDefaultNetwork.networkInfo.getType(),
+                        oldDefaultNetwork, true);
+            }
+            if (newDefaultNetwork != null) {
+                // The new default network can be newly null if and only if the old default
+                // network doesn't satisfy the default request any more because it lost a
+                // capability.
+                mDefaultInetConditionPublished = newDefaultNetwork.lastValidated ? 100 : 0;
+                mLegacyTypeTracker.add(
+                        newDefaultNetwork.networkInfo.getType(), newDefaultNetwork);
+            }
+        }
+
+        // Now that all the callbacks have been sent, send the legacy network broadcasts
+        // as needed. This is necessary so that legacy requests correctly bind dns
+        // requests to this network. The legacy users are listening for this broadcast
+        // and will generally do a dns request so they can ensureRouteToHost and if
+        // they do that before the callbacks happen they'll use the default network.
+        //
+        // TODO: Is there still a race here? The legacy broadcast will be sent after sending
+        // callbacks, but if apps can receive the broadcast before the callback, they still might
+        // have an inconsistent view of networking.
+        //
+        // This *does* introduce a race where if the user uses the new api
+        // (notification callbacks) and then uses the old api (getNetworkInfo(type))
+        // they may get old info. Reverse this after the old startUsing api is removed.
+        // This is on top of the multiple intent sequencing referenced in the todo above.
+        for (NetworkAgentInfo nai : nais) {
+            if (nai.everConnected) {
+                addNetworkToLegacyTypeTracker(nai);
+            }
+        }
+    }
+
+    private void issueNetworkNeeds() {
+        ensureRunningOnConnectivityServiceThread();
+        for (final NetworkOfferInfo noi : mNetworkOffers) {
+            issueNetworkNeeds(noi);
+        }
+    }
+
+    private void issueNetworkNeeds(@NonNull final NetworkOfferInfo noi) {
+        ensureRunningOnConnectivityServiceThread();
+        for (final NetworkRequestInfo nri : mNetworkRequests.values()) {
+            informOffer(nri, noi.offer, mNetworkRanker);
+        }
+    }
+
+    /**
+     * Inform a NetworkOffer about any new situation of a request.
+     *
+     * This function handles updates to offers. A number of events may happen that require
+     * updating the registrant for this offer about the situation :
+     * • The offer itself was updated. This may lead the offer to no longer being able
+     *     to satisfy a request or beat a satisfier (and therefore be no longer needed),
+     *     or conversely being strengthened enough to beat the satisfier (and therefore
+     *     start being needed)
+     * • The network satisfying a request changed (including cases where the request
+     *     starts or stops being satisfied). The new network may be a stronger or weaker
+     *     match than the old one, possibly affecting whether the offer is needed.
+     * • The network satisfying a request updated their score. This may lead the offer
+     *     to no longer be able to beat it if the current satisfier got better, or
+     *     conversely start being a good choice if the current satisfier got weaker.
+     *
+     * @param nri The request
+     * @param offer The offer. This may be an updated offer.
+     */
+    private static void informOffer(@NonNull NetworkRequestInfo nri,
+            @NonNull final NetworkOffer offer, @NonNull final NetworkRanker networkRanker) {
+        final NetworkRequest activeRequest = nri.isBeingSatisfied() ? nri.getActiveRequest() : null;
+        final NetworkAgentInfo satisfier = null != activeRequest ? nri.getSatisfier() : null;
+
+        // Multi-layer requests have a currently active request, the one being satisfied.
+        // Since the system will try to bring up a better network than is currently satisfying
+        // the request, NetworkProviders need to be told the offers matching the requests *above*
+        // the currently satisfied one are needed, that the ones *below* the satisfied one are
+        // not needed, and the offer is needed for the active request iff the offer can beat
+        // the satisfier.
+        // For non-multilayer requests, the logic above gracefully degenerates to only the
+        // last case.
+        // To achieve this, the loop below will proceed in three steps. In a first phase, inform
+        // providers that the offer is needed for this request, until the active request is found.
+        // In a second phase, deal with the currently active request. In a third phase, inform
+        // the providers that offer is unneeded for the remaining requests.
+
+        // First phase : inform providers of all requests above the active request.
+        int i;
+        for (i = 0; nri.mRequests.size() > i; ++i) {
+            final NetworkRequest request = nri.mRequests.get(i);
+            if (activeRequest == request) break; // Found the active request : go to phase 2
+            if (!request.isRequest()) continue; // Listens/track defaults are never sent to offers
+            // Since this request is higher-priority than the one currently satisfied, if the
+            // offer can satisfy it, the provider should try and bring up the network for sure ;
+            // no need to even ask the ranker – an offer that can satisfy is always better than
+            // no network. Hence tell the provider so unless it already knew.
+            if (request.canBeSatisfiedBy(offer.caps) && !offer.neededFor(request)) {
+                offer.onNetworkNeeded(request);
+            }
+        }
+
+        // Second phase : deal with the active request (if any)
+        if (null != activeRequest && activeRequest.isRequest()) {
+            final boolean oldNeeded = offer.neededFor(activeRequest);
+            // An offer is needed if it is currently served by this provider or if this offer
+            // can beat the current satisfier.
+            final boolean currentlyServing = satisfier != null
+                    && satisfier.factorySerialNumber == offer.providerId;
+            final boolean newNeeded = (currentlyServing
+                    || (activeRequest.canBeSatisfiedBy(offer.caps)
+                            && networkRanker.mightBeat(activeRequest, satisfier, offer)));
+            if (newNeeded != oldNeeded) {
+                if (newNeeded) {
+                    offer.onNetworkNeeded(activeRequest);
+                } else {
+                    // The offer used to be able to beat the satisfier. Now it can't.
+                    offer.onNetworkUnneeded(activeRequest);
+                }
+            }
+        }
+
+        // Third phase : inform the providers that the offer isn't needed for any request
+        // below the active one.
+        for (++i /* skip the active request */; nri.mRequests.size() > i; ++i) {
+            final NetworkRequest request = nri.mRequests.get(i);
+            if (!request.isRequest()) continue; // Listens/track defaults are never sent to offers
+            // Since this request is lower-priority than the one currently satisfied, if the
+            // offer can satisfy it, the provider should not try and bring up the network.
+            // Hence tell the provider so unless it already knew.
+            if (offer.neededFor(request)) {
+                offer.onNetworkUnneeded(request);
+            }
+        }
+    }
+
+    private void addNetworkToLegacyTypeTracker(@NonNull final NetworkAgentInfo nai) {
+        for (int i = 0; i < nai.numNetworkRequests(); i++) {
+            NetworkRequest nr = nai.requestAt(i);
+            if (nr.legacyType != TYPE_NONE && nr.isRequest()) {
+                // legacy type tracker filters out repeat adds
+                mLegacyTypeTracker.add(nr.legacyType, nai);
+            }
+        }
+
+        // A VPN generally won't get added to the legacy tracker in the "for (nri)" loop above,
+        // because usually there are no NetworkRequests it satisfies (e.g., mDefaultRequest
+        // wants the NOT_VPN capability, so it will never be satisfied by a VPN). So, add the
+        // newNetwork to the tracker explicitly (it's a no-op if it has already been added).
+        if (nai.isVPN()) {
+            mLegacyTypeTracker.add(TYPE_VPN, nai);
+        }
+    }
+
+    private void updateInetCondition(NetworkAgentInfo nai) {
+        // Don't bother updating until we've graduated to validated at least once.
+        if (!nai.everValidated) return;
+        // For now only update icons for the default connection.
+        // TODO: Update WiFi and cellular icons separately. b/17237507
+        if (!isDefaultNetwork(nai)) return;
+
+        int newInetCondition = nai.lastValidated ? 100 : 0;
+        // Don't repeat publish.
+        if (newInetCondition == mDefaultInetConditionPublished) return;
+
+        mDefaultInetConditionPublished = newInetCondition;
+        sendInetConditionBroadcast(nai.networkInfo);
+    }
+
+    @NonNull
+    private NetworkInfo mixInInfo(@NonNull final NetworkAgentInfo nai, @NonNull NetworkInfo info) {
+        final NetworkInfo newInfo = new NetworkInfo(info);
+        // The suspended and roaming bits are managed in NetworkCapabilities.
+        final boolean suspended =
+                !nai.networkCapabilities.hasCapability(NET_CAPABILITY_NOT_SUSPENDED);
+        if (suspended && info.getDetailedState() == NetworkInfo.DetailedState.CONNECTED) {
+            // Only override the state with SUSPENDED if the network is currently in CONNECTED
+            // state. This is because the network could have been suspended before connecting,
+            // or it could be disconnecting while being suspended, and in both these cases
+            // the state should not be overridden. Note that the only detailed state that
+            // maps to State.CONNECTED is DetailedState.CONNECTED, so there is also no need to
+            // worry about multiple different substates of CONNECTED.
+            newInfo.setDetailedState(NetworkInfo.DetailedState.SUSPENDED, info.getReason(),
+                    info.getExtraInfo());
+        } else if (!suspended && info.getDetailedState() == NetworkInfo.DetailedState.SUSPENDED) {
+            // SUSPENDED state is currently only overridden from CONNECTED state. In the case the
+            // network agent is created, then goes to suspended, then goes out of suspended without
+            // ever setting connected. Check if network agent is ever connected to update the state.
+            newInfo.setDetailedState(nai.everConnected
+                    ? NetworkInfo.DetailedState.CONNECTED
+                    : NetworkInfo.DetailedState.CONNECTING,
+                    info.getReason(),
+                    info.getExtraInfo());
+        }
+        newInfo.setRoaming(!nai.networkCapabilities.hasCapability(NET_CAPABILITY_NOT_ROAMING));
+        return newInfo;
+    }
+
+    private void updateNetworkInfo(NetworkAgentInfo networkAgent, NetworkInfo info) {
+        final NetworkInfo newInfo = mixInInfo(networkAgent, info);
+
+        final NetworkInfo.State state = newInfo.getState();
+        NetworkInfo oldInfo = null;
+        synchronized (networkAgent) {
+            oldInfo = networkAgent.networkInfo;
+            networkAgent.networkInfo = newInfo;
+        }
+
+        if (DBG) {
+            log(networkAgent.toShortString() + " EVENT_NETWORK_INFO_CHANGED, going from "
+                    + oldInfo.getState() + " to " + state);
+        }
+
+        if (!networkAgent.created
+                && (state == NetworkInfo.State.CONNECTED
+                || (state == NetworkInfo.State.CONNECTING && networkAgent.isVPN()))) {
+
+            // A network that has just connected has zero requests and is thus a foreground network.
+            networkAgent.networkCapabilities.addCapability(NET_CAPABILITY_FOREGROUND);
+
+            if (!createNativeNetwork(networkAgent)) return;
+            if (networkAgent.supportsUnderlyingNetworks()) {
+                // Initialize the network's capabilities to their starting values according to the
+                // underlying networks. This ensures that the capabilities are correct before
+                // anything happens to the network.
+                updateCapabilitiesForNetwork(networkAgent);
+            }
+            networkAgent.created = true;
+            networkAgent.onNetworkCreated();
+        }
+
+        if (!networkAgent.everConnected && state == NetworkInfo.State.CONNECTED) {
+            networkAgent.everConnected = true;
+
+            // NetworkCapabilities need to be set before sending the private DNS config to
+            // NetworkMonitor, otherwise NetworkMonitor cannot determine if validation is required.
+            networkAgent.getAndSetNetworkCapabilities(networkAgent.networkCapabilities);
+
+            handlePerNetworkPrivateDnsConfig(networkAgent, mDnsManager.getPrivateDnsConfig());
+            updateLinkProperties(networkAgent, new LinkProperties(networkAgent.linkProperties),
+                    null);
+
+            // Until parceled LinkProperties are sent directly to NetworkMonitor, the connect
+            // command must be sent after updating LinkProperties to maximize chances of
+            // NetworkMonitor seeing the correct LinkProperties when starting.
+            // TODO: pass LinkProperties to the NetworkMonitor in the notifyNetworkConnected call.
+            if (networkAgent.networkAgentConfig.acceptPartialConnectivity) {
+                networkAgent.networkMonitor().setAcceptPartialConnectivity();
+            }
+            networkAgent.networkMonitor().notifyNetworkConnected(
+                    new LinkProperties(networkAgent.linkProperties,
+                            true /* parcelSensitiveFields */),
+                    networkAgent.networkCapabilities);
+            scheduleUnvalidatedPrompt(networkAgent);
+
+            // Whether a particular NetworkRequest listen should cause signal strength thresholds to
+            // be communicated to a particular NetworkAgent depends only on the network's immutable,
+            // capabilities, so it only needs to be done once on initial connect, not every time the
+            // network's capabilities change. Note that we do this before rematching the network,
+            // so we could decide to tear it down immediately afterwards. That's fine though - on
+            // disconnection NetworkAgents should stop any signal strength monitoring they have been
+            // doing.
+            updateSignalStrengthThresholds(networkAgent, "CONNECT", null);
+
+            // Before first rematching networks, put an inactivity timer without any request, this
+            // allows {@code updateInactivityState} to update the state accordingly and prevent
+            // tearing down for any {@code unneeded} evaluation in this period.
+            // Note that the timer will not be rescheduled since the expiry time is
+            // fixed after connection regardless of the network satisfying other requests or not.
+            // But it will be removed as soon as the network satisfies a request for the first time.
+            networkAgent.lingerRequest(NetworkRequest.REQUEST_ID_NONE,
+                    SystemClock.elapsedRealtime(), mNascentDelayMs);
+            networkAgent.setInactive();
+
+            // Consider network even though it is not yet validated.
+            rematchAllNetworksAndRequests();
+
+            // This has to happen after matching the requests, because callbacks are just requests.
+            notifyNetworkCallbacks(networkAgent, ConnectivityManager.CALLBACK_PRECHECK);
+        } else if (state == NetworkInfo.State.DISCONNECTED) {
+            networkAgent.disconnect();
+            if (networkAgent.isVPN()) {
+                updateUids(networkAgent, networkAgent.networkCapabilities, null);
+            }
+            disconnectAndDestroyNetwork(networkAgent);
+            if (networkAgent.isVPN()) {
+                // As the active or bound network changes for apps, broadcast the default proxy, as
+                // apps may need to update their proxy data. This is called after disconnecting from
+                // VPN to make sure we do not broadcast the old proxy data.
+                // TODO(b/122649188): send the broadcast only to VPN users.
+                mProxyTracker.sendProxyBroadcast();
+            }
+        } else if (networkAgent.created && (oldInfo.getState() == NetworkInfo.State.SUSPENDED ||
+                state == NetworkInfo.State.SUSPENDED)) {
+            mLegacyTypeTracker.update(networkAgent);
+        }
+    }
+
+    private void updateNetworkScore(@NonNull final NetworkAgentInfo nai, final NetworkScore score) {
+        if (VDBG || DDBG) log("updateNetworkScore for " + nai.toShortString() + " to " + score);
+        nai.setScore(score);
+        rematchAllNetworksAndRequests();
+    }
+
+    // Notify only this one new request of the current state. Transfer all the
+    // current state by calling NetworkCapabilities and LinkProperties callbacks
+    // so that callers can be guaranteed to have as close to atomicity in state
+    // transfer as can be supported by this current API.
+    protected void notifyNetworkAvailable(NetworkAgentInfo nai, NetworkRequestInfo nri) {
+        mHandler.removeMessages(EVENT_TIMEOUT_NETWORK_REQUEST, nri);
+        if (nri.mPendingIntent != null) {
+            sendPendingIntentForRequest(nri, nai, ConnectivityManager.CALLBACK_AVAILABLE);
+            // Attempt no subsequent state pushes where intents are involved.
+            return;
+        }
+
+        final int blockedReasons = mUidBlockedReasons.get(nri.mAsUid, BLOCKED_REASON_NONE);
+        final boolean metered = nai.networkCapabilities.isMetered();
+        final boolean vpnBlocked = isUidBlockedByVpn(nri.mAsUid, mVpnBlockedUidRanges);
+        callCallbackForRequest(nri, nai, ConnectivityManager.CALLBACK_AVAILABLE,
+                getBlockedState(blockedReasons, metered, vpnBlocked));
+    }
+
+    // Notify the requests on this NAI that the network is now lingered.
+    private void notifyNetworkLosing(@NonNull final NetworkAgentInfo nai, final long now) {
+        final int lingerTime = (int) (nai.getInactivityExpiry() - now);
+        notifyNetworkCallbacks(nai, ConnectivityManager.CALLBACK_LOSING, lingerTime);
+    }
+
+    private static int getBlockedState(int reasons, boolean metered, boolean vpnBlocked) {
+        if (!metered) reasons &= ~BLOCKED_METERED_REASON_MASK;
+        return vpnBlocked
+                ? reasons | BLOCKED_REASON_LOCKDOWN_VPN
+                : reasons & ~BLOCKED_REASON_LOCKDOWN_VPN;
+    }
+
+    private void setUidBlockedReasons(int uid, @BlockedReason int blockedReasons) {
+        if (blockedReasons == BLOCKED_REASON_NONE) {
+            mUidBlockedReasons.delete(uid);
+        } else {
+            mUidBlockedReasons.put(uid, blockedReasons);
+        }
+    }
+
+    /**
+     * Notify of the blocked state apps with a registered callback matching a given NAI.
+     *
+     * Unlike other callbacks, blocked status is different between each individual uid. So for
+     * any given nai, all requests need to be considered according to the uid who filed it.
+     *
+     * @param nai The target NetworkAgentInfo.
+     * @param oldMetered True if the previous network capabilities were metered.
+     * @param newMetered True if the current network capabilities are metered.
+     * @param oldBlockedUidRanges list of UID ranges previously blocked by lockdown VPN.
+     * @param newBlockedUidRanges list of UID ranges blocked by lockdown VPN.
+     */
+    private void maybeNotifyNetworkBlocked(NetworkAgentInfo nai, boolean oldMetered,
+            boolean newMetered, List<UidRange> oldBlockedUidRanges,
+            List<UidRange> newBlockedUidRanges) {
+
+        for (int i = 0; i < nai.numNetworkRequests(); i++) {
+            NetworkRequest nr = nai.requestAt(i);
+            NetworkRequestInfo nri = mNetworkRequests.get(nr);
+
+            final int blockedReasons = mUidBlockedReasons.get(nri.mAsUid, BLOCKED_REASON_NONE);
+            final boolean oldVpnBlocked = isUidBlockedByVpn(nri.mAsUid, oldBlockedUidRanges);
+            final boolean newVpnBlocked = (oldBlockedUidRanges != newBlockedUidRanges)
+                    ? isUidBlockedByVpn(nri.mAsUid, newBlockedUidRanges)
+                    : oldVpnBlocked;
+
+            final int oldBlockedState = getBlockedState(blockedReasons, oldMetered, oldVpnBlocked);
+            final int newBlockedState = getBlockedState(blockedReasons, newMetered, newVpnBlocked);
+            if (oldBlockedState != newBlockedState) {
+                callCallbackForRequest(nri, nai, ConnectivityManager.CALLBACK_BLK_CHANGED,
+                        newBlockedState);
+            }
+        }
+    }
+
+    /**
+     * Notify apps with a given UID of the new blocked state according to new uid state.
+     * @param uid The uid for which the rules changed.
+     * @param blockedReasons The reasons for why an uid is blocked.
+     */
+    private void maybeNotifyNetworkBlockedForNewState(int uid, @BlockedReason int blockedReasons) {
+        for (final NetworkAgentInfo nai : mNetworkAgentInfos) {
+            final boolean metered = nai.networkCapabilities.isMetered();
+            final boolean vpnBlocked = isUidBlockedByVpn(uid, mVpnBlockedUidRanges);
+
+            final int oldBlockedState = getBlockedState(
+                    mUidBlockedReasons.get(uid, BLOCKED_REASON_NONE), metered, vpnBlocked);
+            final int newBlockedState = getBlockedState(blockedReasons, metered, vpnBlocked);
+            if (oldBlockedState == newBlockedState) {
+                continue;
+            }
+            for (int i = 0; i < nai.numNetworkRequests(); i++) {
+                NetworkRequest nr = nai.requestAt(i);
+                NetworkRequestInfo nri = mNetworkRequests.get(nr);
+                if (nri != null && nri.mAsUid == uid) {
+                    callCallbackForRequest(nri, nai, ConnectivityManager.CALLBACK_BLK_CHANGED,
+                            newBlockedState);
+                }
+            }
+        }
+    }
+
+    @VisibleForTesting
+    protected void sendLegacyNetworkBroadcast(NetworkAgentInfo nai, DetailedState state, int type) {
+        // The NetworkInfo we actually send out has no bearing on the real
+        // state of affairs. For example, if the default connection is mobile,
+        // and a request for HIPRI has just gone away, we need to pretend that
+        // HIPRI has just disconnected. So we need to set the type to HIPRI and
+        // the state to DISCONNECTED, even though the network is of type MOBILE
+        // and is still connected.
+        NetworkInfo info = new NetworkInfo(nai.networkInfo);
+        info.setType(type);
+        filterForLegacyLockdown(info);
+        if (state != DetailedState.DISCONNECTED) {
+            info.setDetailedState(state, null, info.getExtraInfo());
+            sendConnectedBroadcast(info);
+        } else {
+            info.setDetailedState(state, info.getReason(), info.getExtraInfo());
+            Intent intent = new Intent(ConnectivityManager.CONNECTIVITY_ACTION);
+            intent.putExtra(ConnectivityManager.EXTRA_NETWORK_INFO, info);
+            intent.putExtra(ConnectivityManager.EXTRA_NETWORK_TYPE, info.getType());
+            if (info.isFailover()) {
+                intent.putExtra(ConnectivityManager.EXTRA_IS_FAILOVER, true);
+                nai.networkInfo.setFailover(false);
+            }
+            if (info.getReason() != null) {
+                intent.putExtra(ConnectivityManager.EXTRA_REASON, info.getReason());
+            }
+            if (info.getExtraInfo() != null) {
+                intent.putExtra(ConnectivityManager.EXTRA_EXTRA_INFO, info.getExtraInfo());
+            }
+            NetworkAgentInfo newDefaultAgent = null;
+            if (nai.isSatisfyingRequest(mDefaultRequest.mRequests.get(0).requestId)) {
+                newDefaultAgent = mDefaultRequest.getSatisfier();
+                if (newDefaultAgent != null) {
+                    intent.putExtra(ConnectivityManager.EXTRA_OTHER_NETWORK_INFO,
+                            newDefaultAgent.networkInfo);
+                } else {
+                    intent.putExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, true);
+                }
+            }
+            intent.putExtra(ConnectivityManager.EXTRA_INET_CONDITION,
+                    mDefaultInetConditionPublished);
+            sendStickyBroadcast(intent);
+            if (newDefaultAgent != null) {
+                sendConnectedBroadcast(newDefaultAgent.networkInfo);
+            }
+        }
+    }
+
+    protected void notifyNetworkCallbacks(NetworkAgentInfo networkAgent, int notifyType, int arg1) {
+        if (VDBG || DDBG) {
+            String notification = ConnectivityManager.getCallbackName(notifyType);
+            log("notifyType " + notification + " for " + networkAgent.toShortString());
+        }
+        for (int i = 0; i < networkAgent.numNetworkRequests(); i++) {
+            NetworkRequest nr = networkAgent.requestAt(i);
+            NetworkRequestInfo nri = mNetworkRequests.get(nr);
+            if (VDBG) log(" sending notification for " + nr);
+            if (nri.mPendingIntent == null) {
+                callCallbackForRequest(nri, networkAgent, notifyType, arg1);
+            } else {
+                sendPendingIntentForRequest(nri, networkAgent, notifyType);
+            }
+        }
+    }
+
+    protected void notifyNetworkCallbacks(NetworkAgentInfo networkAgent, int notifyType) {
+        notifyNetworkCallbacks(networkAgent, notifyType, 0);
+    }
+
+    /**
+     * Returns the list of all interfaces that could be used by network traffic that does not
+     * explicitly specify a network. This includes the default network, but also all VPNs that are
+     * currently connected.
+     *
+     * Must be called on the handler thread.
+     */
+    @NonNull
+    private ArrayList<Network> getDefaultNetworks() {
+        ensureRunningOnConnectivityServiceThread();
+        final ArrayList<Network> defaultNetworks = new ArrayList<>();
+        final Set<Integer> activeNetIds = new ArraySet<>();
+        for (final NetworkRequestInfo nri : mDefaultNetworkRequests) {
+            if (nri.isBeingSatisfied()) {
+                activeNetIds.add(nri.getSatisfier().network().netId);
+            }
+        }
+        for (NetworkAgentInfo nai : mNetworkAgentInfos) {
+            if (nai.everConnected && (activeNetIds.contains(nai.network().netId) || nai.isVPN())) {
+                defaultNetworks.add(nai.network);
+            }
+        }
+        return defaultNetworks;
+    }
+
+    /**
+     * Notify NetworkStatsService that the set of active ifaces has changed, or that one of the
+     * active iface's tracked properties has changed.
+     */
+    private void notifyIfacesChangedForNetworkStats() {
+        ensureRunningOnConnectivityServiceThread();
+        String activeIface = null;
+        LinkProperties activeLinkProperties = getActiveLinkProperties();
+        if (activeLinkProperties != null) {
+            activeIface = activeLinkProperties.getInterfaceName();
+        }
+
+        final UnderlyingNetworkInfo[] underlyingNetworkInfos = getAllVpnInfo();
+        try {
+            final ArrayList<NetworkStateSnapshot> snapshots = new ArrayList<>();
+            // TODO: Directly use NetworkStateSnapshot when feasible.
+            for (final NetworkState state : getAllNetworkState()) {
+                final NetworkStateSnapshot snapshot = new NetworkStateSnapshot(state.network,
+                        state.networkCapabilities, state.linkProperties, state.subscriberId,
+                        state.legacyNetworkType);
+                snapshots.add(snapshot);
+            }
+            mStatsManager.notifyNetworkStatus(getDefaultNetworks(),
+                    snapshots, activeIface, Arrays.asList(underlyingNetworkInfos));
+        } catch (Exception ignored) {
+        }
+    }
+
+    @Override
+    public String getCaptivePortalServerUrl() {
+        enforceNetworkStackOrSettingsPermission();
+        String settingUrl = mResources.get().getString(
+                R.string.config_networkCaptivePortalServerUrl);
+
+        if (!TextUtils.isEmpty(settingUrl)) {
+            return settingUrl;
+        }
+
+        settingUrl = Settings.Global.getString(mContext.getContentResolver(),
+                ConnectivitySettingsManager.CAPTIVE_PORTAL_HTTP_URL);
+        if (!TextUtils.isEmpty(settingUrl)) {
+            return settingUrl;
+        }
+
+        return DEFAULT_CAPTIVE_PORTAL_HTTP_URL;
+    }
+
+    @Override
+    public void startNattKeepalive(Network network, int intervalSeconds,
+            ISocketKeepaliveCallback cb, String srcAddr, int srcPort, String dstAddr) {
+        enforceKeepalivePermission();
+        mKeepaliveTracker.startNattKeepalive(
+                getNetworkAgentInfoForNetwork(network), null /* fd */,
+                intervalSeconds, cb,
+                srcAddr, srcPort, dstAddr, NattSocketKeepalive.NATT_PORT);
+    }
+
+    @Override
+    public void startNattKeepaliveWithFd(Network network, ParcelFileDescriptor pfd, int resourceId,
+            int intervalSeconds, ISocketKeepaliveCallback cb, String srcAddr,
+            String dstAddr) {
+        try {
+            final FileDescriptor fd = pfd.getFileDescriptor();
+            mKeepaliveTracker.startNattKeepalive(
+                    getNetworkAgentInfoForNetwork(network), fd, resourceId,
+                    intervalSeconds, cb,
+                    srcAddr, dstAddr, NattSocketKeepalive.NATT_PORT);
+        } finally {
+            // FileDescriptors coming from AIDL calls must be manually closed to prevent leaks.
+            // startNattKeepalive calls Os.dup(fd) before returning, so we can close immediately.
+            if (pfd != null && Binder.getCallingPid() != Process.myPid()) {
+                IoUtils.closeQuietly(pfd);
+            }
+        }
+    }
+
+    @Override
+    public void startTcpKeepalive(Network network, ParcelFileDescriptor pfd, int intervalSeconds,
+            ISocketKeepaliveCallback cb) {
+        try {
+            enforceKeepalivePermission();
+            final FileDescriptor fd = pfd.getFileDescriptor();
+            mKeepaliveTracker.startTcpKeepalive(
+                    getNetworkAgentInfoForNetwork(network), fd, intervalSeconds, cb);
+        } finally {
+            // FileDescriptors coming from AIDL calls must be manually closed to prevent leaks.
+            // startTcpKeepalive calls Os.dup(fd) before returning, so we can close immediately.
+            if (pfd != null && Binder.getCallingPid() != Process.myPid()) {
+                IoUtils.closeQuietly(pfd);
+            }
+        }
+    }
+
+    @Override
+    public void stopKeepalive(Network network, int slot) {
+        mHandler.sendMessage(mHandler.obtainMessage(
+                NetworkAgent.CMD_STOP_SOCKET_KEEPALIVE, slot, SocketKeepalive.SUCCESS, network));
+    }
+
+    @Override
+    public void factoryReset() {
+        enforceSettingsPermission();
+
+        if (mUserManager.hasUserRestriction(UserManager.DISALLOW_NETWORK_RESET)) {
+            return;
+        }
+
+        final long token = Binder.clearCallingIdentity();
+        try {
+            final IpMemoryStore ipMemoryStore = IpMemoryStore.getMemoryStore(mContext);
+            ipMemoryStore.factoryReset();
+        } finally {
+            Binder.restoreCallingIdentity(token);
+        }
+
+        // Turn airplane mode off
+        setAirplaneMode(false);
+
+        // restore private DNS settings to default mode (opportunistic)
+        if (!mUserManager.hasUserRestriction(UserManager.DISALLOW_CONFIG_PRIVATE_DNS)) {
+            ConnectivitySettingsManager.setPrivateDnsMode(mContext, PRIVATE_DNS_MODE_OPPORTUNISTIC);
+        }
+
+        Settings.Global.putString(mContext.getContentResolver(),
+                ConnectivitySettingsManager.NETWORK_AVOID_BAD_WIFI, null);
+    }
+
+    @Override
+    public byte[] getNetworkWatchlistConfigHash() {
+        NetworkWatchlistManager nwm = mContext.getSystemService(NetworkWatchlistManager.class);
+        if (nwm == null) {
+            loge("Unable to get NetworkWatchlistManager");
+            return null;
+        }
+        // Redirect it to network watchlist service to access watchlist file and calculate hash.
+        return nwm.getWatchlistConfigHash();
+    }
+
+    private void logNetworkEvent(NetworkAgentInfo nai, int evtype) {
+        int[] transports = nai.networkCapabilities.getTransportTypes();
+        mMetricsLog.log(nai.network.getNetId(), transports, new NetworkEvent(evtype));
+    }
+
+    private static boolean toBool(int encodedBoolean) {
+        return encodedBoolean != 0; // Only 0 means false.
+    }
+
+    private static int encodeBool(boolean b) {
+        return b ? 1 : 0;
+    }
+
+    @Override
+    public int handleShellCommand(@NonNull ParcelFileDescriptor in,
+            @NonNull ParcelFileDescriptor out, @NonNull ParcelFileDescriptor err,
+            @NonNull String[] args) {
+        return new ShellCmd().exec(this, in.getFileDescriptor(), out.getFileDescriptor(),
+                err.getFileDescriptor(), args);
+    }
+
+    private class ShellCmd extends BasicShellCommandHandler {
+        @Override
+        public int onCommand(String cmd) {
+            if (cmd == null) {
+                return handleDefaultCommands(cmd);
+            }
+            final PrintWriter pw = getOutPrintWriter();
+            try {
+                switch (cmd) {
+                    case "airplane-mode":
+                        final String action = getNextArg();
+                        if ("enable".equals(action)) {
+                            setAirplaneMode(true);
+                            return 0;
+                        } else if ("disable".equals(action)) {
+                            setAirplaneMode(false);
+                            return 0;
+                        } else if (action == null) {
+                            final ContentResolver cr = mContext.getContentResolver();
+                            final int enabled = Settings.Global.getInt(cr,
+                                    Settings.Global.AIRPLANE_MODE_ON);
+                            pw.println(enabled == 0 ? "disabled" : "enabled");
+                            return 0;
+                        } else {
+                            onHelp();
+                            return -1;
+                        }
+                    default:
+                        return handleDefaultCommands(cmd);
+                }
+            } catch (Exception e) {
+                pw.println(e);
+            }
+            return -1;
+        }
+
+        @Override
+        public void onHelp() {
+            PrintWriter pw = getOutPrintWriter();
+            pw.println("Connectivity service commands:");
+            pw.println("  help");
+            pw.println("    Print this help text.");
+            pw.println("  airplane-mode [enable|disable]");
+            pw.println("    Turn airplane mode on or off.");
+            pw.println("  airplane-mode");
+            pw.println("    Get airplane mode.");
+        }
+    }
+
+    private int getVpnType(@Nullable NetworkAgentInfo vpn) {
+        if (vpn == null) return VpnManager.TYPE_VPN_NONE;
+        final TransportInfo ti = vpn.networkCapabilities.getTransportInfo();
+        if (!(ti instanceof VpnTransportInfo)) return VpnManager.TYPE_VPN_NONE;
+        return ((VpnTransportInfo) ti).getType();
+    }
+
+    /**
+     * @param connectionInfo the connection to resolve.
+     * @return {@code uid} if the connection is found and the app has permission to observe it
+     * (e.g., if it is associated with the calling VPN app's tunnel) or {@code INVALID_UID} if the
+     * connection is not found.
+     */
+    public int getConnectionOwnerUid(ConnectionInfo connectionInfo) {
+        if (connectionInfo.protocol != IPPROTO_TCP && connectionInfo.protocol != IPPROTO_UDP) {
+            throw new IllegalArgumentException("Unsupported protocol " + connectionInfo.protocol);
+        }
+
+        final int uid = mDeps.getConnectionOwnerUid(connectionInfo.protocol,
+                connectionInfo.local, connectionInfo.remote);
+
+        if (uid == INVALID_UID) return uid;  // Not found.
+
+        // Connection owner UIDs are visible only to the network stack and to the VpnService-based
+        // VPN, if any, that applies to the UID that owns the connection.
+        if (checkNetworkStackPermission()) return uid;
+
+        final NetworkAgentInfo vpn = getVpnForUid(uid);
+        if (vpn == null || getVpnType(vpn) != VpnManager.TYPE_VPN_SERVICE
+                || vpn.networkCapabilities.getOwnerUid() != mDeps.getCallingUid()) {
+            return INVALID_UID;
+        }
+
+        return uid;
+    }
+
+    /**
+     * Returns a IBinder to a TestNetworkService. Will be lazily created as needed.
+     *
+     * <p>The TestNetworkService must be run in the system server due to TUN creation.
+     */
+    @Override
+    public IBinder startOrGetTestNetworkService() {
+        synchronized (mTNSLock) {
+            TestNetworkService.enforceTestNetworkPermissions(mContext);
+
+            if (mTNS == null) {
+                mTNS = new TestNetworkService(mContext);
+            }
+
+            return mTNS;
+        }
+    }
+
+    /**
+     * Handler used for managing all Connectivity Diagnostics related functions.
+     *
+     * @see android.net.ConnectivityDiagnosticsManager
+     *
+     * TODO(b/147816404): Explore moving ConnectivityDiagnosticsHandler to a separate file
+     */
+    @VisibleForTesting
+    class ConnectivityDiagnosticsHandler extends Handler {
+        private final String mTag = ConnectivityDiagnosticsHandler.class.getSimpleName();
+
+        /**
+         * Used to handle ConnectivityDiagnosticsCallback registration events from {@link
+         * android.net.ConnectivityDiagnosticsManager}.
+         * obj = ConnectivityDiagnosticsCallbackInfo with IConnectivityDiagnosticsCallback and
+         * NetworkRequestInfo to be registered
+         */
+        private static final int EVENT_REGISTER_CONNECTIVITY_DIAGNOSTICS_CALLBACK = 1;
+
+        /**
+         * Used to handle ConnectivityDiagnosticsCallback unregister events from {@link
+         * android.net.ConnectivityDiagnosticsManager}.
+         * obj = the IConnectivityDiagnosticsCallback to be unregistered
+         * arg1 = the uid of the caller
+         */
+        private static final int EVENT_UNREGISTER_CONNECTIVITY_DIAGNOSTICS_CALLBACK = 2;
+
+        /**
+         * Event for {@link NetworkStateTrackerHandler} to trigger ConnectivityReport callbacks
+         * after processing {@link #EVENT_NETWORK_TESTED} events.
+         * obj = {@link ConnectivityReportEvent} representing ConnectivityReport info reported from
+         * NetworkMonitor.
+         * data = PersistableBundle of extras passed from NetworkMonitor.
+         *
+         * <p>See {@link ConnectivityService#EVENT_NETWORK_TESTED}.
+         */
+        private static final int EVENT_NETWORK_TESTED = ConnectivityService.EVENT_NETWORK_TESTED;
+
+        /**
+         * Event for NetworkMonitor to inform ConnectivityService that a potential data stall has
+         * been detected on the network.
+         * obj = Long the timestamp (in millis) for when the suspected data stall was detected.
+         * arg1 = {@link DataStallReport#DetectionMethod} indicating the detection method.
+         * arg2 = NetID.
+         * data = PersistableBundle of extras passed from NetworkMonitor.
+         */
+        private static final int EVENT_DATA_STALL_SUSPECTED = 4;
+
+        /**
+         * Event for ConnectivityDiagnosticsHandler to handle network connectivity being reported to
+         * the platform. This event will invoke {@link
+         * IConnectivityDiagnosticsCallback#onNetworkConnectivityReported} for permissioned
+         * callbacks.
+         * obj = Network that was reported on
+         * arg1 = boolint for the quality reported
+         */
+        private static final int EVENT_NETWORK_CONNECTIVITY_REPORTED = 5;
+
+        private ConnectivityDiagnosticsHandler(Looper looper) {
+            super(looper);
+        }
+
+        @Override
+        public void handleMessage(Message msg) {
+            switch (msg.what) {
+                case EVENT_REGISTER_CONNECTIVITY_DIAGNOSTICS_CALLBACK: {
+                    handleRegisterConnectivityDiagnosticsCallback(
+                            (ConnectivityDiagnosticsCallbackInfo) msg.obj);
+                    break;
+                }
+                case EVENT_UNREGISTER_CONNECTIVITY_DIAGNOSTICS_CALLBACK: {
+                    handleUnregisterConnectivityDiagnosticsCallback(
+                            (IConnectivityDiagnosticsCallback) msg.obj, msg.arg1);
+                    break;
+                }
+                case EVENT_NETWORK_TESTED: {
+                    final ConnectivityReportEvent reportEvent =
+                            (ConnectivityReportEvent) msg.obj;
+
+                    handleNetworkTestedWithExtras(reportEvent, reportEvent.mExtras);
+                    break;
+                }
+                case EVENT_DATA_STALL_SUSPECTED: {
+                    final NetworkAgentInfo nai = getNetworkAgentInfoForNetId(msg.arg2);
+                    final Pair<Long, PersistableBundle> arg =
+                            (Pair<Long, PersistableBundle>) msg.obj;
+                    if (nai == null) break;
+
+                    handleDataStallSuspected(nai, arg.first, msg.arg1, arg.second);
+                    break;
+                }
+                case EVENT_NETWORK_CONNECTIVITY_REPORTED: {
+                    handleNetworkConnectivityReported((NetworkAgentInfo) msg.obj, toBool(msg.arg1));
+                    break;
+                }
+                default: {
+                    Log.e(mTag, "Unrecognized event in ConnectivityDiagnostics: " + msg.what);
+                }
+            }
+        }
+    }
+
+    /** Class used for cleaning up IConnectivityDiagnosticsCallback instances after their death. */
+    @VisibleForTesting
+    class ConnectivityDiagnosticsCallbackInfo implements Binder.DeathRecipient {
+        @NonNull private final IConnectivityDiagnosticsCallback mCb;
+        @NonNull private final NetworkRequestInfo mRequestInfo;
+        @NonNull private final String mCallingPackageName;
+
+        @VisibleForTesting
+        ConnectivityDiagnosticsCallbackInfo(
+                @NonNull IConnectivityDiagnosticsCallback cb,
+                @NonNull NetworkRequestInfo nri,
+                @NonNull String callingPackageName) {
+            mCb = cb;
+            mRequestInfo = nri;
+            mCallingPackageName = callingPackageName;
+        }
+
+        @Override
+        public void binderDied() {
+            log("ConnectivityDiagnosticsCallback IBinder died.");
+            unregisterConnectivityDiagnosticsCallback(mCb);
+        }
+    }
+
+    /**
+     * Class used for sending information from {@link
+     * NetworkMonitorCallbacks#notifyNetworkTestedWithExtras} to the handler for processing it.
+     */
+    private static class NetworkTestedResults {
+        private final int mNetId;
+        private final int mTestResult;
+        private final long mTimestampMillis;
+        @Nullable private final String mRedirectUrl;
+
+        private NetworkTestedResults(
+                int netId, int testResult, long timestampMillis, @Nullable String redirectUrl) {
+            mNetId = netId;
+            mTestResult = testResult;
+            mTimestampMillis = timestampMillis;
+            mRedirectUrl = redirectUrl;
+        }
+    }
+
+    /**
+     * Class used for sending information from {@link NetworkStateTrackerHandler} to {@link
+     * ConnectivityDiagnosticsHandler}.
+     */
+    private static class ConnectivityReportEvent {
+        private final long mTimestampMillis;
+        @NonNull private final NetworkAgentInfo mNai;
+        private final PersistableBundle mExtras;
+
+        private ConnectivityReportEvent(long timestampMillis, @NonNull NetworkAgentInfo nai,
+                PersistableBundle p) {
+            mTimestampMillis = timestampMillis;
+            mNai = nai;
+            mExtras = p;
+        }
+    }
+
+    private void handleRegisterConnectivityDiagnosticsCallback(
+            @NonNull ConnectivityDiagnosticsCallbackInfo cbInfo) {
+        ensureRunningOnConnectivityServiceThread();
+
+        final IConnectivityDiagnosticsCallback cb = cbInfo.mCb;
+        final IBinder iCb = cb.asBinder();
+        final NetworkRequestInfo nri = cbInfo.mRequestInfo;
+
+        // Connectivity Diagnostics are meant to be used with a single network request. It would be
+        // confusing for these networks to change when an NRI is satisfied in another layer.
+        if (nri.isMultilayerRequest()) {
+            throw new IllegalArgumentException("Connectivity Diagnostics do not support multilayer "
+                + "network requests.");
+        }
+
+        // This means that the client registered the same callback multiple times. Do
+        // not override the previous entry, and exit silently.
+        if (mConnectivityDiagnosticsCallbacks.containsKey(iCb)) {
+            if (VDBG) log("Diagnostics callback is already registered");
+
+            // Decrement the reference count for this NetworkRequestInfo. The reference count is
+            // incremented when the NetworkRequestInfo is created as part of
+            // enforceRequestCountLimit().
+            nri.decrementRequestCount();
+            return;
+        }
+
+        mConnectivityDiagnosticsCallbacks.put(iCb, cbInfo);
+
+        try {
+            iCb.linkToDeath(cbInfo, 0);
+        } catch (RemoteException e) {
+            cbInfo.binderDied();
+            return;
+        }
+
+        // Once registered, provide ConnectivityReports for matching Networks
+        final List<NetworkAgentInfo> matchingNetworks = new ArrayList<>();
+        synchronized (mNetworkForNetId) {
+            for (int i = 0; i < mNetworkForNetId.size(); i++) {
+                final NetworkAgentInfo nai = mNetworkForNetId.valueAt(i);
+                // Connectivity Diagnostics rejects multilayer requests at registration hence get(0)
+                if (nai.satisfies(nri.mRequests.get(0))) {
+                    matchingNetworks.add(nai);
+                }
+            }
+        }
+        for (final NetworkAgentInfo nai : matchingNetworks) {
+            final ConnectivityReport report = nai.getConnectivityReport();
+            if (report == null) {
+                continue;
+            }
+            if (!checkConnectivityDiagnosticsPermissions(
+                    nri.mPid, nri.mUid, nai, cbInfo.mCallingPackageName)) {
+                continue;
+            }
+
+            try {
+                cb.onConnectivityReportAvailable(report);
+            } catch (RemoteException e) {
+                // Exception while sending the ConnectivityReport. Move on to the next network.
+            }
+        }
+    }
+
+    private void handleUnregisterConnectivityDiagnosticsCallback(
+            @NonNull IConnectivityDiagnosticsCallback cb, int uid) {
+        ensureRunningOnConnectivityServiceThread();
+        final IBinder iCb = cb.asBinder();
+
+        final ConnectivityDiagnosticsCallbackInfo cbInfo =
+                mConnectivityDiagnosticsCallbacks.remove(iCb);
+        if (cbInfo == null) {
+            if (VDBG) log("Removing diagnostics callback that is not currently registered");
+            return;
+        }
+
+        final NetworkRequestInfo nri = cbInfo.mRequestInfo;
+
+        // Caller's UID must either be the registrants (if they are unregistering) or the System's
+        // (if the Binder died)
+        if (uid != nri.mUid && uid != Process.SYSTEM_UID) {
+            if (DBG) loge("Uid(" + uid + ") not registrant's (" + nri.mUid + ") or System's");
+            return;
+        }
+
+        // Decrement the reference count for this NetworkRequestInfo. The reference count is
+        // incremented when the NetworkRequestInfo is created as part of
+        // enforceRequestCountLimit().
+        nri.decrementRequestCount();
+
+        iCb.unlinkToDeath(cbInfo, 0);
+    }
+
+    private void handleNetworkTestedWithExtras(
+            @NonNull ConnectivityReportEvent reportEvent, @NonNull PersistableBundle extras) {
+        final NetworkAgentInfo nai = reportEvent.mNai;
+        final NetworkCapabilities networkCapabilities =
+                getNetworkCapabilitiesWithoutUids(nai.networkCapabilities);
+        final ConnectivityReport report =
+                new ConnectivityReport(
+                        reportEvent.mNai.network,
+                        reportEvent.mTimestampMillis,
+                        nai.linkProperties,
+                        networkCapabilities,
+                        extras);
+        nai.setConnectivityReport(report);
+        final List<IConnectivityDiagnosticsCallback> results =
+                getMatchingPermissionedCallbacks(nai);
+        for (final IConnectivityDiagnosticsCallback cb : results) {
+            try {
+                cb.onConnectivityReportAvailable(report);
+            } catch (RemoteException ex) {
+                loge("Error invoking onConnectivityReport", ex);
+            }
+        }
+    }
+
+    private void handleDataStallSuspected(
+            @NonNull NetworkAgentInfo nai, long timestampMillis, int detectionMethod,
+            @NonNull PersistableBundle extras) {
+        final NetworkCapabilities networkCapabilities =
+                getNetworkCapabilitiesWithoutUids(nai.networkCapabilities);
+        final DataStallReport report =
+                new DataStallReport(
+                        nai.network,
+                        timestampMillis,
+                        detectionMethod,
+                        nai.linkProperties,
+                        networkCapabilities,
+                        extras);
+        final List<IConnectivityDiagnosticsCallback> results =
+                getMatchingPermissionedCallbacks(nai);
+        for (final IConnectivityDiagnosticsCallback cb : results) {
+            try {
+                cb.onDataStallSuspected(report);
+            } catch (RemoteException ex) {
+                loge("Error invoking onDataStallSuspected", ex);
+            }
+        }
+    }
+
+    private void handleNetworkConnectivityReported(
+            @NonNull NetworkAgentInfo nai, boolean connectivity) {
+        final List<IConnectivityDiagnosticsCallback> results =
+                getMatchingPermissionedCallbacks(nai);
+        for (final IConnectivityDiagnosticsCallback cb : results) {
+            try {
+                cb.onNetworkConnectivityReported(nai.network, connectivity);
+            } catch (RemoteException ex) {
+                loge("Error invoking onNetworkConnectivityReported", ex);
+            }
+        }
+    }
+
+    private NetworkCapabilities getNetworkCapabilitiesWithoutUids(@NonNull NetworkCapabilities nc) {
+        final NetworkCapabilities sanitized = new NetworkCapabilities(nc,
+                NetworkCapabilities.REDACT_ALL);
+        sanitized.setUids(null);
+        sanitized.setAdministratorUids(new int[0]);
+        sanitized.setOwnerUid(Process.INVALID_UID);
+        return sanitized;
+    }
+
+    private List<IConnectivityDiagnosticsCallback> getMatchingPermissionedCallbacks(
+            @NonNull NetworkAgentInfo nai) {
+        final List<IConnectivityDiagnosticsCallback> results = new ArrayList<>();
+        for (Entry<IBinder, ConnectivityDiagnosticsCallbackInfo> entry :
+                mConnectivityDiagnosticsCallbacks.entrySet()) {
+            final ConnectivityDiagnosticsCallbackInfo cbInfo = entry.getValue();
+            final NetworkRequestInfo nri = cbInfo.mRequestInfo;
+            // Connectivity Diagnostics rejects multilayer requests at registration hence get(0).
+            if (nai.satisfies(nri.mRequests.get(0))) {
+                if (checkConnectivityDiagnosticsPermissions(
+                        nri.mPid, nri.mUid, nai, cbInfo.mCallingPackageName)) {
+                    results.add(entry.getValue().mCb);
+                }
+            }
+        }
+        return results;
+    }
+
+    @VisibleForTesting
+    boolean checkConnectivityDiagnosticsPermissions(
+            int callbackPid, int callbackUid, NetworkAgentInfo nai, String callbackPackageName) {
+        if (checkNetworkStackPermission(callbackPid, callbackUid)) {
+            return true;
+        }
+
+        // LocationPermissionChecker#checkLocationPermission can throw SecurityException if the uid
+        // and package name don't match. Throwing on the CS thread is not acceptable, so wrap the
+        // call in a try-catch.
+        try {
+            if (!mLocationPermissionChecker.checkLocationPermission(
+                    callbackPackageName, null /* featureId */, callbackUid, null /* message */)) {
+                return false;
+            }
+        } catch (SecurityException e) {
+            return false;
+        }
+
+        for (NetworkAgentInfo virtual : mNetworkAgentInfos) {
+            if (virtual.supportsUnderlyingNetworks()
+                    && virtual.networkCapabilities.getOwnerUid() == callbackUid
+                    && CollectionUtils.contains(virtual.declaredUnderlyingNetworks, nai.network)) {
+                return true;
+            }
+        }
+
+        // Administrator UIDs also contains the Owner UID
+        final int[] administratorUids = nai.networkCapabilities.getAdministratorUids();
+        return CollectionUtils.contains(administratorUids, callbackUid);
+    }
+
+    @Override
+    public void registerConnectivityDiagnosticsCallback(
+            @NonNull IConnectivityDiagnosticsCallback callback,
+            @NonNull NetworkRequest request,
+            @NonNull String callingPackageName) {
+        if (request.legacyType != TYPE_NONE) {
+            throw new IllegalArgumentException("ConnectivityManager.TYPE_* are deprecated."
+                    + " Please use NetworkCapabilities instead.");
+        }
+        final int callingUid = mDeps.getCallingUid();
+        mAppOpsManager.checkPackage(callingUid, callingPackageName);
+
+        // This NetworkCapabilities is only used for matching to Networks. Clear out its owner uid
+        // and administrator uids to be safe.
+        final NetworkCapabilities nc = new NetworkCapabilities(request.networkCapabilities);
+        restrictRequestUidsForCallerAndSetRequestorInfo(nc, callingUid, callingPackageName);
+
+        final NetworkRequest requestWithId =
+                new NetworkRequest(
+                        nc, TYPE_NONE, nextNetworkRequestId(), NetworkRequest.Type.LISTEN);
+
+        // NetworkRequestInfos created here count towards MAX_NETWORK_REQUESTS_PER_UID limit.
+        //
+        // nri is not bound to the death of callback. Instead, callback.bindToDeath() is set in
+        // handleRegisterConnectivityDiagnosticsCallback(). nri will be cleaned up as part of the
+        // callback's binder death.
+        final NetworkRequestInfo nri = new NetworkRequestInfo(callingUid, requestWithId);
+        final ConnectivityDiagnosticsCallbackInfo cbInfo =
+                new ConnectivityDiagnosticsCallbackInfo(callback, nri, callingPackageName);
+
+        mConnectivityDiagnosticsHandler.sendMessage(
+                mConnectivityDiagnosticsHandler.obtainMessage(
+                        ConnectivityDiagnosticsHandler
+                                .EVENT_REGISTER_CONNECTIVITY_DIAGNOSTICS_CALLBACK,
+                        cbInfo));
+    }
+
+    @Override
+    public void unregisterConnectivityDiagnosticsCallback(
+            @NonNull IConnectivityDiagnosticsCallback callback) {
+        Objects.requireNonNull(callback, "callback must be non-null");
+        mConnectivityDiagnosticsHandler.sendMessage(
+                mConnectivityDiagnosticsHandler.obtainMessage(
+                        ConnectivityDiagnosticsHandler
+                                .EVENT_UNREGISTER_CONNECTIVITY_DIAGNOSTICS_CALLBACK,
+                        mDeps.getCallingUid(),
+                        0,
+                        callback));
+    }
+
+    @Override
+    public void simulateDataStall(int detectionMethod, long timestampMillis,
+            @NonNull Network network, @NonNull PersistableBundle extras) {
+        enforceAnyPermissionOf(android.Manifest.permission.MANAGE_TEST_NETWORKS,
+                android.Manifest.permission.NETWORK_STACK);
+        final NetworkCapabilities nc = getNetworkCapabilitiesInternal(network);
+        if (!nc.hasTransport(TRANSPORT_TEST)) {
+            throw new SecurityException("Data Stall simluation is only possible for test networks");
+        }
+
+        final NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+        if (nai == null || nai.creatorUid != mDeps.getCallingUid()) {
+            throw new SecurityException("Data Stall simulation is only possible for network "
+                + "creators");
+        }
+
+        // Instead of passing the data stall directly to the ConnectivityDiagnostics handler, treat
+        // this as a Data Stall received directly from NetworkMonitor. This requires wrapping the
+        // Data Stall information as a DataStallReportParcelable and passing to
+        // #notifyDataStallSuspected. This ensures that unknown Data Stall detection methods are
+        // still passed to ConnectivityDiagnostics (with new detection methods masked).
+        final DataStallReportParcelable p = new DataStallReportParcelable();
+        p.timestampMillis = timestampMillis;
+        p.detectionMethod = detectionMethod;
+
+        if (hasDataStallDetectionMethod(p, DETECTION_METHOD_DNS_EVENTS)) {
+            p.dnsConsecutiveTimeouts = extras.getInt(KEY_DNS_CONSECUTIVE_TIMEOUTS);
+        }
+        if (hasDataStallDetectionMethod(p, DETECTION_METHOD_TCP_METRICS)) {
+            p.tcpPacketFailRate = extras.getInt(KEY_TCP_PACKET_FAIL_RATE);
+            p.tcpMetricsCollectionPeriodMillis = extras.getInt(
+                    KEY_TCP_METRICS_COLLECTION_PERIOD_MILLIS);
+        }
+
+        notifyDataStallSuspected(p, network.getNetId());
+    }
+
+    private class NetdCallback extends BaseNetdUnsolicitedEventListener {
+        @Override
+        public void onInterfaceClassActivityChanged(boolean isActive, int transportType,
+                long timestampNs, int uid) {
+            mNetworkActivityTracker.setAndReportNetworkActive(isActive, transportType, timestampNs);
+        }
+
+        @Override
+        public void onInterfaceLinkStateChanged(String iface, boolean up) {
+            for (NetworkAgentInfo nai : mNetworkAgentInfos) {
+                nai.clatd.interfaceLinkStateChanged(iface, up);
+            }
+        }
+
+        @Override
+        public void onInterfaceRemoved(String iface) {
+            for (NetworkAgentInfo nai : mNetworkAgentInfos) {
+                nai.clatd.interfaceRemoved(iface);
+            }
+        }
+    }
+
+    private final LegacyNetworkActivityTracker mNetworkActivityTracker;
+
+    /**
+     * Class used for updating network activity tracking with netd and notify network activity
+     * changes.
+     */
+    private static final class LegacyNetworkActivityTracker {
+        private static final int NO_UID = -1;
+        private final Context mContext;
+        private final INetd mNetd;
+        private final RemoteCallbackList<INetworkActivityListener> mNetworkActivityListeners =
+                new RemoteCallbackList<>();
+        // Indicate the current system default network activity is active or not.
+        @GuardedBy("mActiveIdleTimers")
+        private boolean mNetworkActive;
+        @GuardedBy("mActiveIdleTimers")
+        private final ArrayMap<String, IdleTimerParams> mActiveIdleTimers = new ArrayMap();
+        private final Handler mHandler;
+
+        private class IdleTimerParams {
+            public final int timeout;
+            public final int transportType;
+
+            IdleTimerParams(int timeout, int transport) {
+                this.timeout = timeout;
+                this.transportType = transport;
+            }
+        }
+
+        LegacyNetworkActivityTracker(@NonNull Context context, @NonNull Handler handler,
+                @NonNull INetd netd) {
+            mContext = context;
+            mNetd = netd;
+            mHandler = handler;
+        }
+
+        public void setAndReportNetworkActive(boolean active, int transportType, long tsNanos) {
+            sendDataActivityBroadcast(transportTypeToLegacyType(transportType), active, tsNanos);
+            synchronized (mActiveIdleTimers) {
+                mNetworkActive = active;
+                // If there are no idle timers, it means that system is not monitoring
+                // activity, so the system default network for those default network
+                // unspecified apps is always considered active.
+                //
+                // TODO: If the mActiveIdleTimers is empty, netd will actually not send
+                // any network activity change event. Whenever this event is received,
+                // the mActiveIdleTimers should be always not empty. The legacy behavior
+                // is no-op. Remove to refer to mNetworkActive only.
+                if (mNetworkActive || mActiveIdleTimers.isEmpty()) {
+                    mHandler.sendMessage(mHandler.obtainMessage(EVENT_REPORT_NETWORK_ACTIVITY));
+                }
+            }
+        }
+
+        // The network activity should only be updated from ConnectivityService handler thread
+        // when mActiveIdleTimers lock is held.
+        @GuardedBy("mActiveIdleTimers")
+        private void reportNetworkActive() {
+            final int length = mNetworkActivityListeners.beginBroadcast();
+            if (DDBG) log("reportNetworkActive, notify " + length + " listeners");
+            try {
+                for (int i = 0; i < length; i++) {
+                    try {
+                        mNetworkActivityListeners.getBroadcastItem(i).onNetworkActive();
+                    } catch (RemoteException | RuntimeException e) {
+                        loge("Fail to send network activie to listener " + e);
+                    }
+                }
+            } finally {
+                mNetworkActivityListeners.finishBroadcast();
+            }
+        }
+
+        @GuardedBy("mActiveIdleTimers")
+        public void handleReportNetworkActivity() {
+            synchronized (mActiveIdleTimers) {
+                reportNetworkActive();
+            }
+        }
+
+        // This is deprecated and only to support legacy use cases.
+        private int transportTypeToLegacyType(int type) {
+            switch (type) {
+                case NetworkCapabilities.TRANSPORT_CELLULAR:
+                    return TYPE_MOBILE;
+                case NetworkCapabilities.TRANSPORT_WIFI:
+                    return TYPE_WIFI;
+                case NetworkCapabilities.TRANSPORT_BLUETOOTH:
+                    return TYPE_BLUETOOTH;
+                case NetworkCapabilities.TRANSPORT_ETHERNET:
+                    return TYPE_ETHERNET;
+                default:
+                    loge("Unexpected transport in transportTypeToLegacyType: " + type);
+            }
+            return ConnectivityManager.TYPE_NONE;
+        }
+
+        public void sendDataActivityBroadcast(int deviceType, boolean active, long tsNanos) {
+            final Intent intent = new Intent(ConnectivityManager.ACTION_DATA_ACTIVITY_CHANGE);
+            intent.putExtra(ConnectivityManager.EXTRA_DEVICE_TYPE, deviceType);
+            intent.putExtra(ConnectivityManager.EXTRA_IS_ACTIVE, active);
+            intent.putExtra(ConnectivityManager.EXTRA_REALTIME_NS, tsNanos);
+            final long ident = Binder.clearCallingIdentity();
+            try {
+                mContext.sendOrderedBroadcastAsUser(intent, UserHandle.ALL,
+                        RECEIVE_DATA_ACTIVITY_CHANGE,
+                        null /* resultReceiver */,
+                        null /* scheduler */,
+                        0 /* initialCode */,
+                        null /* initialData */,
+                        null /* initialExtra */);
+            } finally {
+                Binder.restoreCallingIdentity(ident);
+            }
+        }
+
+        /**
+         * Setup data activity tracking for the given network.
+         *
+         * Every {@code setupDataActivityTracking} should be paired with a
+         * {@link #removeDataActivityTracking} for cleanup.
+         */
+        private void setupDataActivityTracking(NetworkAgentInfo networkAgent) {
+            final String iface = networkAgent.linkProperties.getInterfaceName();
+
+            final int timeout;
+            final int type;
+
+            if (networkAgent.networkCapabilities.hasTransport(
+                    NetworkCapabilities.TRANSPORT_CELLULAR)) {
+                timeout = Settings.Global.getInt(mContext.getContentResolver(),
+                        ConnectivitySettingsManager.DATA_ACTIVITY_TIMEOUT_MOBILE,
+                        10);
+                type = NetworkCapabilities.TRANSPORT_CELLULAR;
+            } else if (networkAgent.networkCapabilities.hasTransport(
+                    NetworkCapabilities.TRANSPORT_WIFI)) {
+                timeout = Settings.Global.getInt(mContext.getContentResolver(),
+                        ConnectivitySettingsManager.DATA_ACTIVITY_TIMEOUT_WIFI,
+                        15);
+                type = NetworkCapabilities.TRANSPORT_WIFI;
+            } else {
+                return; // do not track any other networks
+            }
+
+            updateRadioPowerState(true /* isActive */, type);
+
+            if (timeout > 0 && iface != null) {
+                try {
+                    synchronized (mActiveIdleTimers) {
+                        // Networks start up.
+                        mNetworkActive = true;
+                        mActiveIdleTimers.put(iface, new IdleTimerParams(timeout, type));
+                        mNetd.idletimerAddInterface(iface, timeout, Integer.toString(type));
+                        reportNetworkActive();
+                    }
+                } catch (Exception e) {
+                    // You shall not crash!
+                    loge("Exception in setupDataActivityTracking " + e);
+                }
+            }
+        }
+
+        /**
+         * Remove data activity tracking when network disconnects.
+         */
+        private void removeDataActivityTracking(NetworkAgentInfo networkAgent) {
+            final String iface = networkAgent.linkProperties.getInterfaceName();
+            final NetworkCapabilities caps = networkAgent.networkCapabilities;
+
+            if (iface == null) return;
+
+            final int type;
+            if (caps.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR)) {
+                type = NetworkCapabilities.TRANSPORT_CELLULAR;
+            } else if (caps.hasTransport(NetworkCapabilities.TRANSPORT_WIFI)) {
+                type = NetworkCapabilities.TRANSPORT_WIFI;
+            } else {
+                return; // do not track any other networks
+            }
+
+            try {
+                updateRadioPowerState(false /* isActive */, type);
+                synchronized (mActiveIdleTimers) {
+                    final IdleTimerParams params = mActiveIdleTimers.remove(iface);
+                    // The call fails silently if no idle timer setup for this interface
+                    mNetd.idletimerRemoveInterface(iface, params.timeout,
+                            Integer.toString(params.transportType));
+                }
+            } catch (Exception e) {
+                // You shall not crash!
+                loge("Exception in removeDataActivityTracking " + e);
+            }
+        }
+
+        /**
+         * Update data activity tracking when network state is updated.
+         */
+        public void updateDataActivityTracking(NetworkAgentInfo newNetwork,
+                NetworkAgentInfo oldNetwork) {
+            if (newNetwork != null) {
+                setupDataActivityTracking(newNetwork);
+            }
+            if (oldNetwork != null) {
+                removeDataActivityTracking(oldNetwork);
+            }
+        }
+
+        private void updateRadioPowerState(boolean isActive, int transportType) {
+            final BatteryStatsManager bs = mContext.getSystemService(BatteryStatsManager.class);
+            switch (transportType) {
+                case NetworkCapabilities.TRANSPORT_CELLULAR:
+                    bs.reportMobileRadioPowerState(isActive, NO_UID);
+                    break;
+                case NetworkCapabilities.TRANSPORT_WIFI:
+                    bs.reportWifiRadioPowerState(isActive, NO_UID);
+                    break;
+                default:
+                    logw("Untracked transport type:" + transportType);
+            }
+        }
+
+        public boolean isDefaultNetworkActive() {
+            synchronized (mActiveIdleTimers) {
+                // If there are no idle timers, it means that system is not monitoring activity,
+                // so the default network is always considered active.
+                //
+                // TODO : Distinguish between the cases where mActiveIdleTimers is empty because
+                // tracking is disabled (negative idle timer value configured), or no active default
+                // network. In the latter case, this reports active but it should report inactive.
+                return mNetworkActive || mActiveIdleTimers.isEmpty();
+            }
+        }
+
+        public void registerNetworkActivityListener(@NonNull INetworkActivityListener l) {
+            mNetworkActivityListeners.register(l);
+        }
+
+        public void unregisterNetworkActivityListener(@NonNull INetworkActivityListener l) {
+            mNetworkActivityListeners.unregister(l);
+        }
+
+        public void dump(IndentingPrintWriter pw) {
+            synchronized (mActiveIdleTimers) {
+                pw.print("mNetworkActive="); pw.println(mNetworkActive);
+                pw.println("Idle timers:");
+                for (HashMap.Entry<String, IdleTimerParams> ent : mActiveIdleTimers.entrySet()) {
+                    pw.print("  "); pw.print(ent.getKey()); pw.println(":");
+                    final IdleTimerParams params = ent.getValue();
+                    pw.print("    timeout="); pw.print(params.timeout);
+                    pw.print(" type="); pw.println(params.transportType);
+                }
+            }
+        }
+    }
+
+    /**
+     * Registers {@link QosSocketFilter} with {@link IQosCallback}.
+     *
+     * @param socketInfo the socket information
+     * @param callback the callback to register
+     */
+    @Override
+    public void registerQosSocketCallback(@NonNull final QosSocketInfo socketInfo,
+            @NonNull final IQosCallback callback) {
+        final NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(socketInfo.getNetwork());
+        if (nai == null || nai.networkCapabilities == null) {
+            try {
+                callback.onError(QosCallbackException.EX_TYPE_FILTER_NETWORK_RELEASED);
+            } catch (final RemoteException ex) {
+                loge("registerQosCallbackInternal: RemoteException", ex);
+            }
+            return;
+        }
+        registerQosCallbackInternal(new QosSocketFilter(socketInfo), callback, nai);
+    }
+
+    /**
+     * Register a {@link IQosCallback} with base {@link QosFilter}.
+     *
+     * @param filter the filter to register
+     * @param callback the callback to register
+     * @param nai the agent information related to the filter's network
+     */
+    @VisibleForTesting
+    public void registerQosCallbackInternal(@NonNull final QosFilter filter,
+            @NonNull final IQosCallback callback, @NonNull final NetworkAgentInfo nai) {
+        if (filter == null) throw new IllegalArgumentException("filter must be non-null");
+        if (callback == null) throw new IllegalArgumentException("callback must be non-null");
+
+        if (!nai.networkCapabilities.hasCapability(NET_CAPABILITY_NOT_RESTRICTED)) {
+            enforceConnectivityRestrictedNetworksPermission();
+        }
+        mQosCallbackTracker.registerCallback(callback, filter, nai);
+    }
+
+    /**
+     * Unregisters the given callback.
+     *
+     * @param callback the callback to unregister
+     */
+    @Override
+    public void unregisterQosCallback(@NonNull final IQosCallback callback) {
+        Objects.requireNonNull(callback, "callback must be non-null");
+        mQosCallbackTracker.unregisterCallback(callback);
+    }
+
+    // Network preference per-profile and OEM network preferences can't be set at the same
+    // time, because it is unclear what should happen if both preferences are active for
+    // one given UID. To make it possible, the stack would have to clarify what would happen
+    // in case both are active at the same time. The implementation may have to be adjusted
+    // to implement the resulting rules. For example, a priority could be defined between them,
+    // where the OEM preference would be considered less or more important than the enterprise
+    // preference ; this would entail implementing the priorities somehow, e.g. by doing
+    // UID arithmetic with UID ranges or passing a priority to netd so that the routing rules
+    // are set at the right level. Other solutions are possible, e.g. merging of the
+    // preferences for the relevant UIDs.
+    private static void throwConcurrentPreferenceException() {
+        throw new IllegalStateException("Can't set NetworkPreferenceForUser and "
+                + "set OemNetworkPreference at the same time");
+    }
+
+    /**
+     * Request that a user profile is put by default on a network matching a given preference.
+     *
+     * See the documentation for the individual preferences for a description of the supported
+     * behaviors.
+     *
+     * @param profile the profile concerned.
+     * @param preference the preference for this profile, as one of the PROFILE_NETWORK_PREFERENCE_*
+     *                   constants.
+     * @param listener an optional listener to listen for completion of the operation.
+     */
+    @Override
+    public void setProfileNetworkPreference(@NonNull final UserHandle profile,
+            @ConnectivityManager.ProfileNetworkPreference final int preference,
+            @Nullable final IOnCompleteListener listener) {
+        Objects.requireNonNull(profile);
+        PermissionUtils.enforceNetworkStackPermission(mContext);
+        if (DBG) {
+            log("setProfileNetworkPreference " + profile + " to " + preference);
+        }
+        if (profile.getIdentifier() < 0) {
+            throw new IllegalArgumentException("Must explicitly specify a user handle ("
+                    + "UserHandle.CURRENT not supported)");
+        }
+        final UserManager um = mContext.getSystemService(UserManager.class);
+        if (!um.isManagedProfile(profile.getIdentifier())) {
+            throw new IllegalArgumentException("Profile must be a managed profile");
+        }
+        // Strictly speaking, mOemNetworkPreferences should only be touched on the
+        // handler thread. However it is an immutable object, so reading the reference is
+        // safe - it's just possible the value is slightly outdated. For the final check,
+        // see #handleSetProfileNetworkPreference. But if this can be caught here it is a
+        // lot easier to understand, so opportunistically check it.
+        if (!mOemNetworkPreferences.isEmpty()) {
+            throwConcurrentPreferenceException();
+        }
+        final NetworkCapabilities nc;
+        switch (preference) {
+            case ConnectivityManager.PROFILE_NETWORK_PREFERENCE_DEFAULT:
+                nc = null;
+                break;
+            case ConnectivityManager.PROFILE_NETWORK_PREFERENCE_ENTERPRISE:
+                final UidRange uids = UidRange.createForUser(profile);
+                nc = createDefaultNetworkCapabilitiesForUidRange(uids);
+                nc.addCapability(NET_CAPABILITY_ENTERPRISE);
+                nc.removeCapability(NET_CAPABILITY_NOT_RESTRICTED);
+                break;
+            default:
+                throw new IllegalArgumentException(
+                        "Invalid preference in setProfileNetworkPreference");
+        }
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_SET_PROFILE_NETWORK_PREFERENCE,
+                new Pair<>(new ProfileNetworkPreferences.Preference(profile, nc), listener)));
+    }
+
+    private void validateNetworkCapabilitiesOfProfileNetworkPreference(
+            @Nullable final NetworkCapabilities nc) {
+        if (null == nc) return; // Null caps are always allowed. It means to remove the setting.
+        ensureRequestableCapabilities(nc);
+    }
+
+    private ArraySet<NetworkRequestInfo> createNrisFromProfileNetworkPreferences(
+            @NonNull final ProfileNetworkPreferences prefs) {
+        final ArraySet<NetworkRequestInfo> result = new ArraySet<>();
+        for (final ProfileNetworkPreferences.Preference pref : prefs.preferences) {
+            // The NRI for a user should be comprised of two layers:
+            // - The request for the capabilities
+            // - The request for the default network, for fallback. Create an image of it to
+            //   have the correct UIDs in it (also a request can only be part of one NRI, because
+            //   of lookups in 1:1 associations like mNetworkRequests).
+            // Note that denying a fallback can be implemented simply by not adding the second
+            // request.
+            final ArrayList<NetworkRequest> nrs = new ArrayList<>();
+            nrs.add(createNetworkRequest(NetworkRequest.Type.REQUEST, pref.capabilities));
+            nrs.add(createDefaultInternetRequestForTransport(
+                    TYPE_NONE, NetworkRequest.Type.TRACK_DEFAULT));
+            setNetworkRequestUids(nrs, UidRange.fromIntRanges(pref.capabilities.getUids()));
+            final NetworkRequestInfo nri = new NetworkRequestInfo(Process.myUid(), nrs);
+            result.add(nri);
+        }
+        return result;
+    }
+
+    private void handleSetProfileNetworkPreference(
+            @NonNull final ProfileNetworkPreferences.Preference preference,
+            @Nullable final IOnCompleteListener listener) {
+        // setProfileNetworkPreference and setOemNetworkPreference are mutually exclusive, in
+        // particular because it's not clear what preference should win in case both apply
+        // to the same app.
+        // The binder call has already checked this, but as mOemNetworkPreferences is only
+        // touched on the handler thread, it's theoretically not impossible that it has changed
+        // since.
+        if (!mOemNetworkPreferences.isEmpty()) {
+            // This may happen on a device with an OEM preference set when a user is removed.
+            // In this case, it's safe to ignore. In particular this happens in the tests.
+            loge("handleSetProfileNetworkPreference, but OEM network preferences not empty");
+            return;
+        }
+
+        validateNetworkCapabilitiesOfProfileNetworkPreference(preference.capabilities);
+
+        mProfileNetworkPreferences = mProfileNetworkPreferences.plus(preference);
+        mSystemNetworkRequestCounter.transact(
+                mDeps.getCallingUid(), mProfileNetworkPreferences.preferences.size(),
+                () -> {
+                    final ArraySet<NetworkRequestInfo> nris =
+                            createNrisFromProfileNetworkPreferences(mProfileNetworkPreferences);
+                    replaceDefaultNetworkRequestsForPreference(nris);
+                });
+        // Finally, rematch.
+        rematchAllNetworksAndRequests();
+
+        if (null != listener) {
+            try {
+                listener.onComplete();
+            } catch (RemoteException e) {
+                loge("Listener for setProfileNetworkPreference has died");
+            }
+        }
+    }
+
+    private void enforceAutomotiveDevice() {
+        final boolean isAutomotiveDevice =
+                mContext.getPackageManager().hasSystemFeature(PackageManager.FEATURE_AUTOMOTIVE);
+        if (!isAutomotiveDevice) {
+            throw new UnsupportedOperationException(
+                    "setOemNetworkPreference() is only available on automotive devices.");
+        }
+    }
+
+    /**
+     * Used by automotive devices to set the network preferences used to direct traffic at an
+     * application level as per the given OemNetworkPreferences. An example use-case would be an
+     * automotive OEM wanting to provide connectivity for applications critical to the usage of a
+     * vehicle via a particular network.
+     *
+     * Calling this will overwrite the existing preference.
+     *
+     * @param preference {@link OemNetworkPreferences} The application network preference to be set.
+     * @param listener {@link ConnectivityManager.OnCompleteListener} Listener used
+     * to communicate completion of setOemNetworkPreference();
+     */
+    @Override
+    public void setOemNetworkPreference(
+            @NonNull final OemNetworkPreferences preference,
+            @Nullable final IOnCompleteListener listener) {
+
+        enforceAutomotiveDevice();
+        enforceOemNetworkPreferencesPermission();
+
+        if (!mProfileNetworkPreferences.isEmpty()) {
+            // Strictly speaking, mProfileNetworkPreferences should only be touched on the
+            // handler thread. However it is an immutable object, so reading the reference is
+            // safe - it's just possible the value is slightly outdated. For the final check,
+            // see #handleSetOemPreference. But if this can be caught here it is a
+            // lot easier to understand, so opportunistically check it.
+            throwConcurrentPreferenceException();
+        }
+
+        Objects.requireNonNull(preference, "OemNetworkPreferences must be non-null");
+        validateOemNetworkPreferences(preference);
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_SET_OEM_NETWORK_PREFERENCE,
+                new Pair<>(preference, listener)));
+    }
+
+    private void validateOemNetworkPreferences(@NonNull OemNetworkPreferences preference) {
+        for (@OemNetworkPreferences.OemNetworkPreference final int pref
+                : preference.getNetworkPreferences().values()) {
+            if (OemNetworkPreferences.OEM_NETWORK_PREFERENCE_UNINITIALIZED == pref) {
+                final String msg = "OEM_NETWORK_PREFERENCE_UNINITIALIZED is an invalid value.";
+                throw new IllegalArgumentException(msg);
+            }
+        }
+    }
+
+    private void handleSetOemNetworkPreference(
+            @NonNull final OemNetworkPreferences preference,
+            @Nullable final IOnCompleteListener listener) {
+        Objects.requireNonNull(preference, "OemNetworkPreferences must be non-null");
+        if (DBG) {
+            log("set OEM network preferences :" + preference.toString());
+        }
+        // setProfileNetworkPreference and setOemNetworkPreference are mutually exclusive, in
+        // particular because it's not clear what preference should win in case both apply
+        // to the same app.
+        // The binder call has already checked this, but as mOemNetworkPreferences is only
+        // touched on the handler thread, it's theoretically not impossible that it has changed
+        // since.
+        if (!mProfileNetworkPreferences.isEmpty()) {
+            logwtf("handleSetOemPreference, but per-profile network preferences not empty");
+            return;
+        }
+
+        mOemNetworkPreferencesLogs.log("UPDATE INITIATED: " + preference);
+        final int uniquePreferenceCount = new ArraySet<>(
+                preference.getNetworkPreferences().values()).size();
+        mSystemNetworkRequestCounter.transact(
+                mDeps.getCallingUid(), uniquePreferenceCount,
+                () -> {
+                    final ArraySet<NetworkRequestInfo> nris =
+                            new OemNetworkRequestFactory()
+                                    .createNrisFromOemNetworkPreferences(preference);
+                    replaceDefaultNetworkRequestsForPreference(nris);
+                });
+        mOemNetworkPreferences = preference;
+
+        if (null != listener) {
+            try {
+                listener.onComplete();
+            } catch (RemoteException e) {
+                loge("Can't send onComplete in handleSetOemNetworkPreference", e);
+            }
+        }
+    }
+
+    private void replaceDefaultNetworkRequestsForPreference(
+            @NonNull final Set<NetworkRequestInfo> nris) {
+        // Pass in a defensive copy as this collection will be updated on remove.
+        handleRemoveNetworkRequests(new ArraySet<>(mDefaultNetworkRequests));
+        addPerAppDefaultNetworkRequests(nris);
+    }
+
+    private void addPerAppDefaultNetworkRequests(@NonNull final Set<NetworkRequestInfo> nris) {
+        ensureRunningOnConnectivityServiceThread();
+        mDefaultNetworkRequests.addAll(nris);
+        final ArraySet<NetworkRequestInfo> perAppCallbackRequestsToUpdate =
+                getPerAppCallbackRequestsToUpdate();
+        final ArraySet<NetworkRequestInfo> nrisToRegister = new ArraySet<>(nris);
+        mSystemNetworkRequestCounter.transact(
+                mDeps.getCallingUid(), perAppCallbackRequestsToUpdate.size(),
+                () -> {
+                    nrisToRegister.addAll(
+                            createPerAppCallbackRequestsToRegister(perAppCallbackRequestsToUpdate));
+                    handleRemoveNetworkRequests(perAppCallbackRequestsToUpdate);
+                    handleRegisterNetworkRequests(nrisToRegister);
+                });
+    }
+
+    /**
+     * All current requests that are tracking the default network need to be assessed as to whether
+     * or not the current set of per-application default requests will be changing their default
+     * network. If so, those requests will need to be updated so that they will send callbacks for
+     * default network changes at the appropriate time. Additionally, those requests tracking the
+     * default that were previously updated by this flow will need to be reassessed.
+     * @return the nris which will need to be updated.
+     */
+    private ArraySet<NetworkRequestInfo> getPerAppCallbackRequestsToUpdate() {
+        final ArraySet<NetworkRequestInfo> defaultCallbackRequests = new ArraySet<>();
+        // Get the distinct nris to check since for multilayer requests, it is possible to have the
+        // same nri in the map's values for each of its NetworkRequest objects.
+        final ArraySet<NetworkRequestInfo> nris = new ArraySet<>(mNetworkRequests.values());
+        for (final NetworkRequestInfo nri : nris) {
+            // Include this nri if it is currently being tracked.
+            if (isPerAppTrackedNri(nri)) {
+                defaultCallbackRequests.add(nri);
+                continue;
+            }
+            // We only track callbacks for requests tracking the default.
+            if (NetworkRequest.Type.TRACK_DEFAULT != nri.mRequests.get(0).type) {
+                continue;
+            }
+            // Include this nri if it will be tracked by the new per-app default requests.
+            final boolean isNriGoingToBeTracked =
+                    getDefaultRequestTrackingUid(nri.mAsUid) != mDefaultRequest;
+            if (isNriGoingToBeTracked) {
+                defaultCallbackRequests.add(nri);
+            }
+        }
+        return defaultCallbackRequests;
+    }
+
+    /**
+     * Create nris for those network requests that are currently tracking the default network that
+     * are being controlled by a per-application default.
+     * @param perAppCallbackRequestsForUpdate the baseline network requests to be used as the
+     * foundation when creating the nri. Important items include the calling uid's original
+     * NetworkRequest to be used when mapping callbacks as well as the caller's uid and name. These
+     * requests are assumed to have already been validated as needing to be updated.
+     * @return the Set of nris to use when registering network requests.
+     */
+    private ArraySet<NetworkRequestInfo> createPerAppCallbackRequestsToRegister(
+            @NonNull final ArraySet<NetworkRequestInfo> perAppCallbackRequestsForUpdate) {
+        final ArraySet<NetworkRequestInfo> callbackRequestsToRegister = new ArraySet<>();
+        for (final NetworkRequestInfo callbackRequest : perAppCallbackRequestsForUpdate) {
+            final NetworkRequestInfo trackingNri =
+                    getDefaultRequestTrackingUid(callbackRequest.mAsUid);
+
+            // If this nri is not being tracked, the change it back to an untracked nri.
+            if (trackingNri == mDefaultRequest) {
+                callbackRequestsToRegister.add(new NetworkRequestInfo(
+                        callbackRequest,
+                        Collections.singletonList(callbackRequest.getNetworkRequestForCallback())));
+                continue;
+            }
+
+            final NetworkRequest request = callbackRequest.mRequests.get(0);
+            callbackRequestsToRegister.add(new NetworkRequestInfo(
+                    callbackRequest,
+                    copyNetworkRequestsForUid(
+                            trackingNri.mRequests, callbackRequest.mAsUid,
+                            callbackRequest.mUid, request.getRequestorPackageName())));
+        }
+        return callbackRequestsToRegister;
+    }
+
+    private static void setNetworkRequestUids(@NonNull final List<NetworkRequest> requests,
+            @NonNull final Set<UidRange> uids) {
+        for (final NetworkRequest req : requests) {
+            req.networkCapabilities.setUids(UidRange.toIntRanges(uids));
+        }
+    }
+
+    /**
+     * Class used to generate {@link NetworkRequestInfo} based off of {@link OemNetworkPreferences}.
+     */
+    @VisibleForTesting
+    final class OemNetworkRequestFactory {
+        ArraySet<NetworkRequestInfo> createNrisFromOemNetworkPreferences(
+                @NonNull final OemNetworkPreferences preference) {
+            final ArraySet<NetworkRequestInfo> nris = new ArraySet<>();
+            final SparseArray<Set<Integer>> uids =
+                    createUidsFromOemNetworkPreferences(preference);
+            for (int i = 0; i < uids.size(); i++) {
+                final int key = uids.keyAt(i);
+                final Set<Integer> value = uids.valueAt(i);
+                final NetworkRequestInfo nri = createNriFromOemNetworkPreferences(key, value);
+                // No need to add an nri without any requests.
+                if (0 == nri.mRequests.size()) {
+                    continue;
+                }
+                nris.add(nri);
+            }
+
+            return nris;
+        }
+
+        private SparseArray<Set<Integer>> createUidsFromOemNetworkPreferences(
+                @NonNull final OemNetworkPreferences preference) {
+            final SparseArray<Set<Integer>> uids = new SparseArray<>();
+            final PackageManager pm = mContext.getPackageManager();
+            final List<UserHandle> users =
+                    mContext.getSystemService(UserManager.class).getUserHandles(true);
+            if (null == users || users.size() == 0) {
+                if (VDBG || DDBG) {
+                    log("No users currently available for setting the OEM network preference.");
+                }
+                return uids;
+            }
+            for (final Map.Entry<String, Integer> entry :
+                    preference.getNetworkPreferences().entrySet()) {
+                @OemNetworkPreferences.OemNetworkPreference final int pref = entry.getValue();
+                try {
+                    final int uid = pm.getApplicationInfo(entry.getKey(), 0).uid;
+                    if (!uids.contains(pref)) {
+                        uids.put(pref, new ArraySet<>());
+                    }
+                    for (final UserHandle ui : users) {
+                        // Add the rules for all users as this policy is device wide.
+                        uids.get(pref).add(ui.getUid(uid));
+                    }
+                } catch (PackageManager.NameNotFoundException e) {
+                    // Although this may seem like an error scenario, it is ok that uninstalled
+                    // packages are sent on a network preference as the system will watch for
+                    // package installations associated with this network preference and update
+                    // accordingly. This is done so as to minimize race conditions on app install.
+                    continue;
+                }
+            }
+            return uids;
+        }
+
+        private NetworkRequestInfo createNriFromOemNetworkPreferences(
+                @OemNetworkPreferences.OemNetworkPreference final int preference,
+                @NonNull final Set<Integer> uids) {
+            final List<NetworkRequest> requests = new ArrayList<>();
+            // Requests will ultimately be evaluated by order of insertion therefore it matters.
+            switch (preference) {
+                case OemNetworkPreferences.OEM_NETWORK_PREFERENCE_OEM_PAID:
+                    requests.add(createUnmeteredNetworkRequest());
+                    requests.add(createOemPaidNetworkRequest());
+                    requests.add(createDefaultInternetRequestForTransport(
+                            TYPE_NONE, NetworkRequest.Type.TRACK_DEFAULT));
+                    break;
+                case OemNetworkPreferences.OEM_NETWORK_PREFERENCE_OEM_PAID_NO_FALLBACK:
+                    requests.add(createUnmeteredNetworkRequest());
+                    requests.add(createOemPaidNetworkRequest());
+                    break;
+                case OemNetworkPreferences.OEM_NETWORK_PREFERENCE_OEM_PAID_ONLY:
+                    requests.add(createOemPaidNetworkRequest());
+                    break;
+                case OemNetworkPreferences.OEM_NETWORK_PREFERENCE_OEM_PRIVATE_ONLY:
+                    requests.add(createOemPrivateNetworkRequest());
+                    break;
+                default:
+                    // This should never happen.
+                    throw new IllegalArgumentException("createNriFromOemNetworkPreferences()"
+                            + " called with invalid preference of " + preference);
+            }
+
+            final ArraySet ranges = new ArraySet<Integer>();
+            for (final int uid : uids) {
+                ranges.add(new UidRange(uid, uid));
+            }
+            setNetworkRequestUids(requests, ranges);
+            return new NetworkRequestInfo(Process.myUid(), requests);
+        }
+
+        private NetworkRequest createUnmeteredNetworkRequest() {
+            final NetworkCapabilities netcap = createDefaultPerAppNetCap()
+                    .addCapability(NET_CAPABILITY_NOT_METERED)
+                    .addCapability(NET_CAPABILITY_VALIDATED);
+            return createNetworkRequest(NetworkRequest.Type.LISTEN, netcap);
+        }
+
+        private NetworkRequest createOemPaidNetworkRequest() {
+            // NET_CAPABILITY_OEM_PAID is a restricted capability.
+            final NetworkCapabilities netcap = createDefaultPerAppNetCap()
+                    .addCapability(NET_CAPABILITY_OEM_PAID)
+                    .removeCapability(NET_CAPABILITY_NOT_RESTRICTED);
+            return createNetworkRequest(NetworkRequest.Type.REQUEST, netcap);
+        }
+
+        private NetworkRequest createOemPrivateNetworkRequest() {
+            // NET_CAPABILITY_OEM_PRIVATE is a restricted capability.
+            final NetworkCapabilities netcap = createDefaultPerAppNetCap()
+                    .addCapability(NET_CAPABILITY_OEM_PRIVATE)
+                    .removeCapability(NET_CAPABILITY_NOT_RESTRICTED);
+            return createNetworkRequest(NetworkRequest.Type.REQUEST, netcap);
+        }
+
+        private NetworkCapabilities createDefaultPerAppNetCap() {
+            final NetworkCapabilities netCap = new NetworkCapabilities();
+            netCap.addCapability(NET_CAPABILITY_INTERNET);
+            netCap.setRequestorUidAndPackageName(Process.myUid(), mContext.getPackageName());
+            return netCap;
+        }
+    }
+}
diff --git a/service/src/com/android/server/ConnectivityServiceInitializer.java b/service/src/com/android/server/ConnectivityServiceInitializer.java
new file mode 100644
index 0000000..2465479
--- /dev/null
+++ b/service/src/com/android/server/ConnectivityServiceInitializer.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server;
+
+import android.content.Context;
+import android.util.Log;
+
+/**
+ * Connectivity service initializer for core networking. This is called by system server to create
+ * a new instance of ConnectivityService.
+ */
+public final class ConnectivityServiceInitializer extends SystemService {
+    private static final String TAG = ConnectivityServiceInitializer.class.getSimpleName();
+    private final ConnectivityService mConnectivity;
+
+    public ConnectivityServiceInitializer(Context context) {
+        super(context);
+        // Load JNI libraries used by ConnectivityService and its dependencies
+        System.loadLibrary("service-connectivity");
+        // TODO: Define formal APIs to get the needed services.
+        mConnectivity = new ConnectivityService(context);
+    }
+
+    @Override
+    public void onStart() {
+        Log.i(TAG, "Registering " + Context.CONNECTIVITY_SERVICE);
+        publishBinderService(Context.CONNECTIVITY_SERVICE, mConnectivity,
+                /* allowIsolated= */ false);
+    }
+}
diff --git a/service/src/com/android/server/NetIdManager.java b/service/src/com/android/server/NetIdManager.java
new file mode 100644
index 0000000..61925c8
--- /dev/null
+++ b/service/src/com/android/server/NetIdManager.java
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server;
+
+import android.annotation.NonNull;
+import android.net.ConnectivityManager;
+import android.util.SparseBooleanArray;
+
+import com.android.internal.annotations.GuardedBy;
+import com.android.internal.annotations.VisibleForTesting;
+
+/**
+ * Class used to reserve and release net IDs.
+ *
+ * <p>Instances of this class are thread-safe.
+ */
+public class NetIdManager {
+    // Sequence number for Networks; keep in sync with system/netd/NetworkController.cpp
+    public static final int MIN_NET_ID = 100; // some reserved marks
+    // Top IDs reserved by IpSecService
+    public static final int MAX_NET_ID = ConnectivityManager.getIpSecNetIdRange().getLower() - 1;
+
+    @GuardedBy("mNetIdInUse")
+    private final SparseBooleanArray mNetIdInUse = new SparseBooleanArray();
+
+    @GuardedBy("mNetIdInUse")
+    private int mLastNetId = MIN_NET_ID - 1;
+
+    private final int mMaxNetId;
+
+    public NetIdManager() {
+        this(MAX_NET_ID);
+    }
+
+    @VisibleForTesting
+    NetIdManager(int maxNetId) {
+        mMaxNetId = maxNetId;
+    }
+
+    /**
+     * Get the first netId that follows the provided lastId and is available.
+     */
+    private int getNextAvailableNetIdLocked(
+            int lastId, @NonNull SparseBooleanArray netIdInUse) {
+        int netId = lastId;
+        for (int i = MIN_NET_ID; i <= mMaxNetId; i++) {
+            netId = netId < mMaxNetId ? netId + 1 : MIN_NET_ID;
+            if (!netIdInUse.get(netId)) {
+                return netId;
+            }
+        }
+        throw new IllegalStateException("No free netIds");
+    }
+
+    /**
+     * Reserve a new ID for a network.
+     */
+    public int reserveNetId() {
+        synchronized (mNetIdInUse) {
+            mLastNetId = getNextAvailableNetIdLocked(mLastNetId, mNetIdInUse);
+            // Make sure NetID unused.  http://b/16815182
+            mNetIdInUse.put(mLastNetId, true);
+            return mLastNetId;
+        }
+    }
+
+    /**
+     * Clear a previously reserved ID for a network.
+     */
+    public void releaseNetId(int id) {
+        synchronized (mNetIdInUse) {
+            mNetIdInUse.delete(id);
+        }
+    }
+}
diff --git a/service/src/com/android/server/TestNetworkService.java b/service/src/com/android/server/TestNetworkService.java
new file mode 100644
index 0000000..09873f4
--- /dev/null
+++ b/service/src/com/android/server/TestNetworkService.java
@@ -0,0 +1,387 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server;
+
+import static android.net.TestNetworkManager.TEST_TAP_PREFIX;
+import static android.net.TestNetworkManager.TEST_TUN_PREFIX;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.content.Context;
+import android.net.ConnectivityManager;
+import android.net.INetd;
+import android.net.ITestNetworkManager;
+import android.net.IpPrefix;
+import android.net.LinkAddress;
+import android.net.LinkProperties;
+import android.net.NetworkAgent;
+import android.net.NetworkAgentConfig;
+import android.net.NetworkCapabilities;
+import android.net.NetworkProvider;
+import android.net.RouteInfo;
+import android.net.TestNetworkInterface;
+import android.net.TestNetworkSpecifier;
+import android.os.Binder;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.IBinder;
+import android.os.Looper;
+import android.os.ParcelFileDescriptor;
+import android.os.RemoteException;
+import android.util.SparseArray;
+
+import com.android.internal.annotations.GuardedBy;
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.net.module.util.NetdUtils;
+import com.android.net.module.util.NetworkStackConstants;
+import com.android.net.module.util.PermissionUtils;
+
+import java.io.UncheckedIOException;
+import java.net.Inet4Address;
+import java.net.Inet6Address;
+import java.net.InterfaceAddress;
+import java.net.NetworkInterface;
+import java.net.SocketException;
+import java.util.ArrayList;
+import java.util.Objects;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/** @hide */
+class TestNetworkService extends ITestNetworkManager.Stub {
+    @NonNull private static final String TEST_NETWORK_LOGTAG = "TestNetworkAgent";
+    @NonNull private static final String TEST_NETWORK_PROVIDER_NAME = "TestNetworkProvider";
+    @NonNull private static final AtomicInteger sTestTunIndex = new AtomicInteger();
+
+    @NonNull private final Context mContext;
+    @NonNull private final INetd mNetd;
+
+    @NonNull private final HandlerThread mHandlerThread;
+    @NonNull private final Handler mHandler;
+
+    @NonNull private final ConnectivityManager mCm;
+    @NonNull private final NetworkProvider mNetworkProvider;
+
+    // Native method stubs
+    private static native int jniCreateTunTap(boolean isTun, @NonNull String iface);
+
+    @VisibleForTesting
+    protected TestNetworkService(@NonNull Context context) {
+        mHandlerThread = new HandlerThread("TestNetworkServiceThread");
+        mHandlerThread.start();
+        mHandler = new Handler(mHandlerThread.getLooper());
+
+        mContext = Objects.requireNonNull(context, "missing Context");
+        mNetd = Objects.requireNonNull(
+                INetd.Stub.asInterface((IBinder) context.getSystemService(Context.NETD_SERVICE)),
+                "could not get netd instance");
+        mCm = mContext.getSystemService(ConnectivityManager.class);
+        mNetworkProvider = new NetworkProvider(mContext, mHandler.getLooper(),
+                TEST_NETWORK_PROVIDER_NAME);
+        final long token = Binder.clearCallingIdentity();
+        try {
+            mCm.registerNetworkProvider(mNetworkProvider);
+        } finally {
+            Binder.restoreCallingIdentity(token);
+        }
+    }
+
+    /**
+     * Create a TUN or TAP interface with the given interface name and link addresses
+     *
+     * <p>This method will return the FileDescriptor to the interface. Close it to tear down the
+     * interface.
+     */
+    private TestNetworkInterface createInterface(boolean isTun, LinkAddress[] linkAddrs) {
+        enforceTestNetworkPermissions(mContext);
+
+        Objects.requireNonNull(linkAddrs, "missing linkAddrs");
+
+        String ifacePrefix = isTun ? TEST_TUN_PREFIX : TEST_TAP_PREFIX;
+        String iface = ifacePrefix + sTestTunIndex.getAndIncrement();
+        final long token = Binder.clearCallingIdentity();
+        try {
+            ParcelFileDescriptor tunIntf =
+                    ParcelFileDescriptor.adoptFd(jniCreateTunTap(isTun, iface));
+            for (LinkAddress addr : linkAddrs) {
+                mNetd.interfaceAddAddress(
+                        iface,
+                        addr.getAddress().getHostAddress(),
+                        addr.getPrefixLength());
+            }
+
+            return new TestNetworkInterface(tunIntf, iface);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        } finally {
+            Binder.restoreCallingIdentity(token);
+        }
+    }
+
+    /**
+     * Create a TUN interface with the given interface name and link addresses
+     *
+     * <p>This method will return the FileDescriptor to the TUN interface. Close it to tear down the
+     * TUN interface.
+     */
+    @Override
+    public TestNetworkInterface createTunInterface(@NonNull LinkAddress[] linkAddrs) {
+        return createInterface(true, linkAddrs);
+    }
+
+    /**
+     * Create a TAP interface with the given interface name
+     *
+     * <p>This method will return the FileDescriptor to the TAP interface. Close it to tear down the
+     * TAP interface.
+     */
+    @Override
+    public TestNetworkInterface createTapInterface() {
+        return createInterface(false, new LinkAddress[0]);
+    }
+
+    // Tracker for TestNetworkAgents
+    @GuardedBy("mTestNetworkTracker")
+    @NonNull
+    private final SparseArray<TestNetworkAgent> mTestNetworkTracker = new SparseArray<>();
+
+    public class TestNetworkAgent extends NetworkAgent implements IBinder.DeathRecipient {
+        private static final int NETWORK_SCORE = 1; // Use a low, non-zero score.
+
+        private final int mUid;
+
+        @GuardedBy("mBinderLock")
+        @NonNull
+        private IBinder mBinder;
+
+        @NonNull private final Object mBinderLock = new Object();
+
+        private TestNetworkAgent(
+                @NonNull Context context,
+                @NonNull Looper looper,
+                @NonNull NetworkCapabilities nc,
+                @NonNull LinkProperties lp,
+                @NonNull NetworkAgentConfig config,
+                int uid,
+                @NonNull IBinder binder,
+                @NonNull NetworkProvider np)
+                throws RemoteException {
+            super(context, looper, TEST_NETWORK_LOGTAG, nc, lp, NETWORK_SCORE, config, np);
+            mUid = uid;
+            synchronized (mBinderLock) {
+                mBinder = binder; // Binder null-checks in create()
+
+                try {
+                    mBinder.linkToDeath(this, 0);
+                } catch (RemoteException e) {
+                    binderDied();
+                    throw e; // Abort, signal failure up the stack.
+                }
+            }
+        }
+
+        /**
+         * If the Binder object dies, this function is called to free the resources of this
+         * TestNetworkAgent
+         */
+        @Override
+        public void binderDied() {
+            teardown();
+        }
+
+        @Override
+        protected void unwanted() {
+            teardown();
+        }
+
+        private void teardown() {
+            unregister();
+
+            // Synchronize on mBinderLock to ensure that unlinkToDeath is never called more than
+            // once (otherwise it could throw an exception)
+            synchronized (mBinderLock) {
+                // If mBinder is null, this Test Network has already been cleaned up.
+                if (mBinder == null) return;
+                mBinder.unlinkToDeath(this, 0);
+                mBinder = null;
+            }
+
+            // Has to be in TestNetworkAgent to ensure all teardown codepaths properly clean up
+            // resources, even for binder death or unwanted calls.
+            synchronized (mTestNetworkTracker) {
+                mTestNetworkTracker.remove(getNetwork().getNetId());
+            }
+        }
+    }
+
+    private TestNetworkAgent registerTestNetworkAgent(
+            @NonNull Looper looper,
+            @NonNull Context context,
+            @NonNull String iface,
+            @Nullable LinkProperties lp,
+            boolean isMetered,
+            int callingUid,
+            @NonNull int[] administratorUids,
+            @NonNull IBinder binder)
+            throws RemoteException, SocketException {
+        Objects.requireNonNull(looper, "missing Looper");
+        Objects.requireNonNull(context, "missing Context");
+        // iface and binder validity checked by caller
+
+        // Build narrow set of NetworkCapabilities, useful only for testing
+        NetworkCapabilities nc = new NetworkCapabilities();
+        nc.clearAll(); // Remove default capabilities.
+        nc.addTransportType(NetworkCapabilities.TRANSPORT_TEST);
+        nc.addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_SUSPENDED);
+        nc.addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED);
+        nc.addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VCN_MANAGED);
+        nc.setNetworkSpecifier(new TestNetworkSpecifier(iface));
+        nc.setAdministratorUids(administratorUids);
+        if (!isMetered) {
+            nc.addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_METERED);
+        }
+
+        // Build LinkProperties
+        if (lp == null) {
+            lp = new LinkProperties();
+        } else {
+            lp = new LinkProperties(lp);
+            // Use LinkAddress(es) from the interface itself to minimize how much the caller
+            // is trusted.
+            lp.setLinkAddresses(new ArrayList<>());
+        }
+        lp.setInterfaceName(iface);
+
+        // Find the currently assigned addresses, and add them to LinkProperties
+        boolean allowIPv4 = false, allowIPv6 = false;
+        NetworkInterface netIntf = NetworkInterface.getByName(iface);
+        Objects.requireNonNull(netIntf, "No such network interface found: " + netIntf);
+
+        for (InterfaceAddress intfAddr : netIntf.getInterfaceAddresses()) {
+            lp.addLinkAddress(
+                    new LinkAddress(intfAddr.getAddress(), intfAddr.getNetworkPrefixLength()));
+
+            if (intfAddr.getAddress() instanceof Inet6Address) {
+                allowIPv6 |= !intfAddr.getAddress().isLinkLocalAddress();
+            } else if (intfAddr.getAddress() instanceof Inet4Address) {
+                allowIPv4 = true;
+            }
+        }
+
+        // Add global routes (but as non-default, non-internet providing network)
+        if (allowIPv4) {
+            lp.addRoute(new RouteInfo(new IpPrefix(
+                    NetworkStackConstants.IPV4_ADDR_ANY, 0), null, iface));
+        }
+        if (allowIPv6) {
+            lp.addRoute(new RouteInfo(new IpPrefix(
+                    NetworkStackConstants.IPV6_ADDR_ANY, 0), null, iface));
+        }
+
+        final TestNetworkAgent agent = new TestNetworkAgent(context, looper, nc, lp,
+                new NetworkAgentConfig.Builder().build(), callingUid, binder,
+                mNetworkProvider);
+        agent.register();
+        agent.markConnected();
+        return agent;
+    }
+
+    /**
+     * Sets up a Network with extremely limited privileges, guarded by the MANAGE_TEST_NETWORKS
+     * permission.
+     *
+     * <p>This method provides a Network that is useful only for testing.
+     */
+    @Override
+    public void setupTestNetwork(
+            @NonNull String iface,
+            @Nullable LinkProperties lp,
+            boolean isMetered,
+            @NonNull int[] administratorUids,
+            @NonNull IBinder binder) {
+        enforceTestNetworkPermissions(mContext);
+
+        Objects.requireNonNull(iface, "missing Iface");
+        Objects.requireNonNull(binder, "missing IBinder");
+
+        if (!(iface.startsWith(INetd.IPSEC_INTERFACE_PREFIX)
+                || iface.startsWith(TEST_TUN_PREFIX))) {
+            throw new IllegalArgumentException(
+                    "Cannot create network for non ipsec, non-testtun interface");
+        }
+
+        try {
+            final long token = Binder.clearCallingIdentity();
+            try {
+                PermissionUtils.enforceNetworkStackPermission(mContext);
+                NetdUtils.setInterfaceUp(mNetd, iface);
+            } finally {
+                Binder.restoreCallingIdentity(token);
+            }
+
+            // Synchronize all accesses to mTestNetworkTracker to prevent the case where:
+            // 1. TestNetworkAgent successfully binds to death of binder
+            // 2. Before it is added to the mTestNetworkTracker, binder dies, binderDied() is called
+            // (on a different thread)
+            // 3. This thread is pre-empted, put() is called after remove()
+            synchronized (mTestNetworkTracker) {
+                TestNetworkAgent agent =
+                        registerTestNetworkAgent(
+                                mHandler.getLooper(),
+                                mContext,
+                                iface,
+                                lp,
+                                isMetered,
+                                Binder.getCallingUid(),
+                                administratorUids,
+                                binder);
+
+                mTestNetworkTracker.put(agent.getNetwork().getNetId(), agent);
+            }
+        } catch (SocketException e) {
+            throw new UncheckedIOException(e);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /** Teardown a test network */
+    @Override
+    public void teardownTestNetwork(int netId) {
+        enforceTestNetworkPermissions(mContext);
+
+        final TestNetworkAgent agent;
+        synchronized (mTestNetworkTracker) {
+            agent = mTestNetworkTracker.get(netId);
+        }
+
+        if (agent == null) {
+            return; // Already torn down
+        } else if (agent.mUid != Binder.getCallingUid()) {
+            throw new SecurityException("Attempted to modify other user's test networks");
+        }
+
+        // Safe to be called multiple times.
+        agent.teardown();
+    }
+
+    private static final String PERMISSION_NAME =
+            android.Manifest.permission.MANAGE_TEST_NETWORKS;
+
+    public static void enforceTestNetworkPermissions(@NonNull Context context) {
+        context.enforceCallingOrSelfPermission(PERMISSION_NAME, "TestNetworkService");
+    }
+}
diff --git a/service/src/com/android/server/connectivity/AutodestructReference.java b/service/src/com/android/server/connectivity/AutodestructReference.java
new file mode 100644
index 0000000..009a43e
--- /dev/null
+++ b/service/src/com/android/server/connectivity/AutodestructReference.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import android.annotation.NonNull;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * A ref that autodestructs at the first usage of it.
+ * @param <T> The type of the held object
+ * @hide
+ */
+public class AutodestructReference<T> {
+    private final AtomicReference<T> mHeld;
+    public AutodestructReference(@NonNull T obj) {
+        if (null == obj) throw new NullPointerException("Autodestruct reference to null");
+        mHeld = new AtomicReference<>(obj);
+    }
+
+    /** Get the ref and destruct it. NPE if already destructed. */
+    @NonNull
+    public T getAndDestroy() {
+        final T obj = mHeld.getAndSet(null);
+        if (null == obj) throw new NullPointerException("Already autodestructed");
+        return obj;
+    }
+}
diff --git a/service/src/com/android/server/connectivity/DnsManager.java b/service/src/com/android/server/connectivity/DnsManager.java
new file mode 100644
index 0000000..05b12ba
--- /dev/null
+++ b/service/src/com/android/server/connectivity/DnsManager.java
@@ -0,0 +1,494 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.net.ConnectivitySettingsManager.DNS_RESOLVER_MAX_SAMPLES;
+import static android.net.ConnectivitySettingsManager.DNS_RESOLVER_MIN_SAMPLES;
+import static android.net.ConnectivitySettingsManager.DNS_RESOLVER_SAMPLE_VALIDITY_SECONDS;
+import static android.net.ConnectivitySettingsManager.DNS_RESOLVER_SUCCESS_THRESHOLD_PERCENT;
+import static android.net.ConnectivitySettingsManager.PRIVATE_DNS_DEFAULT_MODE;
+import static android.net.ConnectivitySettingsManager.PRIVATE_DNS_MODE;
+import static android.net.ConnectivitySettingsManager.PRIVATE_DNS_MODE_OFF;
+import static android.net.ConnectivitySettingsManager.PRIVATE_DNS_MODE_PROVIDER_HOSTNAME;
+import static android.net.ConnectivitySettingsManager.PRIVATE_DNS_SPECIFIER;
+import static android.net.resolv.aidl.IDnsResolverUnsolicitedEventListener.VALIDATION_RESULT_FAILURE;
+import static android.net.resolv.aidl.IDnsResolverUnsolicitedEventListener.VALIDATION_RESULT_SUCCESS;
+
+import android.annotation.NonNull;
+import android.content.ContentResolver;
+import android.content.Context;
+import android.content.Intent;
+import android.net.ConnectivityManager;
+import android.net.ConnectivitySettingsManager;
+import android.net.IDnsResolver;
+import android.net.InetAddresses;
+import android.net.LinkProperties;
+import android.net.Network;
+import android.net.ResolverOptionsParcel;
+import android.net.ResolverParamsParcel;
+import android.net.Uri;
+import android.net.shared.PrivateDnsConfig;
+import android.os.Binder;
+import android.os.RemoteException;
+import android.os.ServiceSpecificException;
+import android.os.UserHandle;
+import android.provider.Settings;
+import android.text.TextUtils;
+import android.util.Log;
+import android.util.Pair;
+
+import java.net.InetAddress;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.stream.Collectors;
+
+/**
+ * Encapsulate the management of DNS settings for networks.
+ *
+ * This class it NOT designed for concurrent access. Furthermore, all non-static
+ * methods MUST be called from ConnectivityService's thread. However, an exceptional
+ * case is getPrivateDnsConfig(Network) which is exclusively for
+ * ConnectivityService#dumpNetworkDiagnostics() on a random binder thread.
+ *
+ * [ Private DNS ]
+ * The code handling Private DNS is spread across several components, but this
+ * seems like the least bad place to collect all the observations.
+ *
+ * Private DNS handling and updating occurs in response to several different
+ * events. Each is described here with its corresponding intended handling.
+ *
+ * [A] Event: A new network comes up.
+ * Mechanics:
+ *     [1] ConnectivityService gets notifications from NetworkAgents.
+ *     [2] in updateNetworkInfo(), the first time the NetworkAgent goes into
+ *         into CONNECTED state, the Private DNS configuration is retrieved,
+ *         programmed, and strict mode hostname resolution (if applicable) is
+ *         enqueued in NetworkAgent's NetworkMonitor, via a call to
+ *         handlePerNetworkPrivateDnsConfig().
+ *     [3] Re-resolution of strict mode hostnames that fail to return any
+ *         IP addresses happens inside NetworkMonitor; it sends itself a
+ *         delayed CMD_EVALUATE_PRIVATE_DNS message in a simple backoff
+ *         schedule.
+ *     [4] Successfully resolved hostnames are sent to ConnectivityService
+ *         inside an EVENT_PRIVATE_DNS_CONFIG_RESOLVED message. The resolved
+ *         IP addresses are programmed into netd via:
+ *
+ *             updatePrivateDns() -> updateDnses()
+ *
+ *         both of which make calls into DnsManager.
+ *     [5] Upon a successful hostname resolution NetworkMonitor initiates a
+ *         validation attempt in the form of a lookup for a one-time hostname
+ *         that uses Private DNS.
+ *
+ * [B] Event: Private DNS settings are changed.
+ * Mechanics:
+ *     [1] ConnectivityService gets notifications from its SettingsObserver.
+ *     [2] handlePrivateDnsSettingsChanged() is called, which calls
+ *         handlePerNetworkPrivateDnsConfig() and the process proceeds
+ *         as if from A.3 above.
+ *
+ * [C] Event: An application calls ConnectivityManager#reportBadNetwork().
+ * Mechanics:
+ *     [1] NetworkMonitor is notified and initiates a reevaluation, which
+ *         always bypasses Private DNS.
+ *     [2] Once completed, NetworkMonitor checks if strict mode is in operation
+ *         and if so enqueues another evaluation of Private DNS, as if from
+ *         step A.5 above.
+ *
+ * @hide
+ */
+public class DnsManager {
+    private static final String TAG = DnsManager.class.getSimpleName();
+    private static final PrivateDnsConfig PRIVATE_DNS_OFF = new PrivateDnsConfig();
+
+    /* Defaults for resolver parameters. */
+    private static final int DNS_RESOLVER_DEFAULT_SAMPLE_VALIDITY_SECONDS = 1800;
+    private static final int DNS_RESOLVER_DEFAULT_SUCCESS_THRESHOLD_PERCENT = 25;
+    private static final int DNS_RESOLVER_DEFAULT_MIN_SAMPLES = 8;
+    private static final int DNS_RESOLVER_DEFAULT_MAX_SAMPLES = 64;
+
+    /**
+     * Get PrivateDnsConfig.
+     */
+    public static PrivateDnsConfig getPrivateDnsConfig(Context context) {
+        final int mode = ConnectivitySettingsManager.getPrivateDnsMode(context);
+
+        final boolean useTls = mode != PRIVATE_DNS_MODE_OFF;
+
+        if (PRIVATE_DNS_MODE_PROVIDER_HOSTNAME == mode) {
+            final String specifier = getStringSetting(context.getContentResolver(),
+                    PRIVATE_DNS_SPECIFIER);
+            return new PrivateDnsConfig(specifier, null);
+        }
+
+        return new PrivateDnsConfig(useTls);
+    }
+
+    public static Uri[] getPrivateDnsSettingsUris() {
+        return new Uri[]{
+            Settings.Global.getUriFor(PRIVATE_DNS_DEFAULT_MODE),
+            Settings.Global.getUriFor(PRIVATE_DNS_MODE),
+            Settings.Global.getUriFor(PRIVATE_DNS_SPECIFIER),
+        };
+    }
+
+    public static class PrivateDnsValidationUpdate {
+        public final int netId;
+        public final InetAddress ipAddress;
+        public final String hostname;
+        // Refer to IDnsResolverUnsolicitedEventListener.VALIDATION_RESULT_*.
+        public final int validationResult;
+
+        public PrivateDnsValidationUpdate(int netId, InetAddress ipAddress,
+                String hostname, int validationResult) {
+            this.netId = netId;
+            this.ipAddress = ipAddress;
+            this.hostname = hostname;
+            this.validationResult = validationResult;
+        }
+    }
+
+    private static class PrivateDnsValidationStatuses {
+        enum ValidationStatus {
+            IN_PROGRESS,
+            FAILED,
+            SUCCEEDED
+        }
+
+        // Validation statuses of <hostname, ipAddress> pairs for a single netId
+        // Caution : not thread-safe. As mentioned in the top file comment, all
+        // methods of this class must only be called on ConnectivityService's thread.
+        private Map<Pair<String, InetAddress>, ValidationStatus> mValidationMap;
+
+        private PrivateDnsValidationStatuses() {
+            mValidationMap = new HashMap<>();
+        }
+
+        private boolean hasValidatedServer() {
+            for (ValidationStatus status : mValidationMap.values()) {
+                if (status == ValidationStatus.SUCCEEDED) {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        private void updateTrackedDnses(String[] ipAddresses, String hostname) {
+            Set<Pair<String, InetAddress>> latestDnses = new HashSet<>();
+            for (String ipAddress : ipAddresses) {
+                try {
+                    latestDnses.add(new Pair(hostname,
+                            InetAddresses.parseNumericAddress(ipAddress)));
+                } catch (IllegalArgumentException e) {}
+            }
+            // Remove <hostname, ipAddress> pairs that should not be tracked.
+            for (Iterator<Map.Entry<Pair<String, InetAddress>, ValidationStatus>> it =
+                    mValidationMap.entrySet().iterator(); it.hasNext(); ) {
+                Map.Entry<Pair<String, InetAddress>, ValidationStatus> entry = it.next();
+                if (!latestDnses.contains(entry.getKey())) {
+                    it.remove();
+                }
+            }
+            // Add new <hostname, ipAddress> pairs that should be tracked.
+            for (Pair<String, InetAddress> p : latestDnses) {
+                if (!mValidationMap.containsKey(p)) {
+                    mValidationMap.put(p, ValidationStatus.IN_PROGRESS);
+                }
+            }
+        }
+
+        private void updateStatus(PrivateDnsValidationUpdate update) {
+            Pair<String, InetAddress> p = new Pair(update.hostname,
+                    update.ipAddress);
+            if (!mValidationMap.containsKey(p)) {
+                return;
+            }
+            if (update.validationResult == VALIDATION_RESULT_SUCCESS) {
+                mValidationMap.put(p, ValidationStatus.SUCCEEDED);
+            } else if (update.validationResult == VALIDATION_RESULT_FAILURE) {
+                mValidationMap.put(p, ValidationStatus.FAILED);
+            } else {
+                Log.e(TAG, "Unknown private dns validation operation="
+                        + update.validationResult);
+            }
+        }
+
+        private LinkProperties fillInValidatedPrivateDns(LinkProperties lp) {
+            lp.setValidatedPrivateDnsServers(Collections.EMPTY_LIST);
+            mValidationMap.forEach((key, value) -> {
+                    if (value == ValidationStatus.SUCCEEDED) {
+                        lp.addValidatedPrivateDnsServer(key.second);
+                    }
+                });
+            return lp;
+        }
+    }
+
+    private final Context mContext;
+    private final ContentResolver mContentResolver;
+    private final IDnsResolver mDnsResolver;
+    private final ConcurrentHashMap<Integer, PrivateDnsConfig> mPrivateDnsMap;
+    // TODO: Replace the Map with SparseArrays.
+    private final Map<Integer, PrivateDnsValidationStatuses> mPrivateDnsValidationMap;
+    private final Map<Integer, LinkProperties> mLinkPropertiesMap;
+    private final Map<Integer, int[]> mTransportsMap;
+
+    private int mSampleValidity;
+    private int mSuccessThreshold;
+    private int mMinSamples;
+    private int mMaxSamples;
+
+    public DnsManager(Context ctx, IDnsResolver dnsResolver) {
+        mContext = ctx;
+        mContentResolver = mContext.getContentResolver();
+        mDnsResolver = dnsResolver;
+        mPrivateDnsMap = new ConcurrentHashMap<>();
+        mPrivateDnsValidationMap = new HashMap<>();
+        mLinkPropertiesMap = new HashMap<>();
+        mTransportsMap = new HashMap<>();
+
+        // TODO: Create and register ContentObservers to track every setting
+        // used herein, posting messages to respond to changes.
+    }
+
+    public PrivateDnsConfig getPrivateDnsConfig() {
+        return getPrivateDnsConfig(mContext);
+    }
+
+    public void removeNetwork(Network network) {
+        mPrivateDnsMap.remove(network.getNetId());
+        mPrivateDnsValidationMap.remove(network.getNetId());
+        mTransportsMap.remove(network.getNetId());
+        mLinkPropertiesMap.remove(network.getNetId());
+    }
+
+    // This is exclusively called by ConnectivityService#dumpNetworkDiagnostics() which
+    // is not on the ConnectivityService handler thread.
+    public PrivateDnsConfig getPrivateDnsConfig(@NonNull Network network) {
+        return mPrivateDnsMap.getOrDefault(network.getNetId(), PRIVATE_DNS_OFF);
+    }
+
+    public PrivateDnsConfig updatePrivateDns(Network network, PrivateDnsConfig cfg) {
+        Log.w(TAG, "updatePrivateDns(" + network + ", " + cfg + ")");
+        return (cfg != null)
+                ? mPrivateDnsMap.put(network.getNetId(), cfg)
+                : mPrivateDnsMap.remove(network.getNetId());
+    }
+
+    public void updatePrivateDnsStatus(int netId, LinkProperties lp) {
+        // Use the PrivateDnsConfig data pushed to this class instance
+        // from ConnectivityService.
+        final PrivateDnsConfig privateDnsCfg = mPrivateDnsMap.getOrDefault(netId,
+                PRIVATE_DNS_OFF);
+
+        final boolean useTls = privateDnsCfg.useTls;
+        final PrivateDnsValidationStatuses statuses =
+                useTls ? mPrivateDnsValidationMap.get(netId) : null;
+        final boolean validated = (null != statuses) && statuses.hasValidatedServer();
+        final boolean strictMode = privateDnsCfg.inStrictMode();
+        final String tlsHostname = strictMode ? privateDnsCfg.hostname : null;
+        final boolean usingPrivateDns = strictMode || validated;
+
+        lp.setUsePrivateDns(usingPrivateDns);
+        lp.setPrivateDnsServerName(tlsHostname);
+        if (usingPrivateDns && null != statuses) {
+            statuses.fillInValidatedPrivateDns(lp);
+        } else {
+            lp.setValidatedPrivateDnsServers(Collections.EMPTY_LIST);
+        }
+    }
+
+    public void updatePrivateDnsValidation(PrivateDnsValidationUpdate update) {
+        final PrivateDnsValidationStatuses statuses = mPrivateDnsValidationMap.get(update.netId);
+        if (statuses == null) return;
+        statuses.updateStatus(update);
+    }
+
+    /**
+     * When creating a new network or transport types are changed in a specific network,
+     * transport types are always saved to a hashMap before update dns config.
+     * When destroying network, the specific network will be removed from the hashMap.
+     * The hashMap is always accessed on the same thread.
+     */
+    public void updateTransportsForNetwork(int netId, @NonNull int[] transportTypes) {
+        mTransportsMap.put(netId, transportTypes);
+        sendDnsConfigurationForNetwork(netId);
+    }
+
+    /**
+     * When {@link LinkProperties} are changed in a specific network, they are
+     * always saved to a hashMap before update dns config.
+     * When destroying network, the specific network will be removed from the hashMap.
+     * The hashMap is always accessed on the same thread.
+     */
+    public void noteDnsServersForNetwork(int netId, @NonNull LinkProperties lp) {
+        mLinkPropertiesMap.put(netId, lp);
+        sendDnsConfigurationForNetwork(netId);
+    }
+
+    /**
+     * Send dns configuration parameters to resolver for a given network.
+     */
+    public void sendDnsConfigurationForNetwork(int netId) {
+        final LinkProperties lp = mLinkPropertiesMap.get(netId);
+        final int[] transportTypes = mTransportsMap.get(netId);
+        if (lp == null || transportTypes == null) return;
+        updateParametersSettings();
+        final ResolverParamsParcel paramsParcel = new ResolverParamsParcel();
+
+        // We only use the PrivateDnsConfig data pushed to this class instance
+        // from ConnectivityService because it works in coordination with
+        // NetworkMonitor to decide which networks need validation and runs the
+        // blocking calls to resolve Private DNS strict mode hostnames.
+        //
+        // At this time we do not attempt to enable Private DNS on non-Internet
+        // networks like IMS.
+        final PrivateDnsConfig privateDnsCfg = mPrivateDnsMap.getOrDefault(netId,
+                PRIVATE_DNS_OFF);
+        final boolean useTls = privateDnsCfg.useTls;
+        final boolean strictMode = privateDnsCfg.inStrictMode();
+
+        paramsParcel.netId = netId;
+        paramsParcel.sampleValiditySeconds = mSampleValidity;
+        paramsParcel.successThreshold = mSuccessThreshold;
+        paramsParcel.minSamples = mMinSamples;
+        paramsParcel.maxSamples = mMaxSamples;
+        paramsParcel.servers = makeStrings(lp.getDnsServers());
+        paramsParcel.domains = getDomainStrings(lp.getDomains());
+        paramsParcel.tlsName = strictMode ? privateDnsCfg.hostname : "";
+        paramsParcel.tlsServers =
+                strictMode ? makeStrings(
+                        Arrays.stream(privateDnsCfg.ips)
+                              .filter((ip) -> lp.isReachable(ip))
+                              .collect(Collectors.toList()))
+                : useTls ? paramsParcel.servers  // Opportunistic
+                : new String[0];            // Off
+        paramsParcel.resolverOptions = new ResolverOptionsParcel();
+        paramsParcel.transportTypes = transportTypes;
+        // Prepare to track the validation status of the DNS servers in the
+        // resolver config when private DNS is in opportunistic or strict mode.
+        if (useTls) {
+            if (!mPrivateDnsValidationMap.containsKey(netId)) {
+                mPrivateDnsValidationMap.put(netId, new PrivateDnsValidationStatuses());
+            }
+            mPrivateDnsValidationMap.get(netId).updateTrackedDnses(paramsParcel.tlsServers,
+                    paramsParcel.tlsName);
+        } else {
+            mPrivateDnsValidationMap.remove(netId);
+        }
+
+        Log.d(TAG, String.format("sendDnsConfigurationForNetwork(%d, %s, %s, %d, %d, %d, %d, "
+                + "%d, %d, %s, %s)", paramsParcel.netId, Arrays.toString(paramsParcel.servers),
+                Arrays.toString(paramsParcel.domains), paramsParcel.sampleValiditySeconds,
+                paramsParcel.successThreshold, paramsParcel.minSamples,
+                paramsParcel.maxSamples, paramsParcel.baseTimeoutMsec,
+                paramsParcel.retryCount, paramsParcel.tlsName,
+                Arrays.toString(paramsParcel.tlsServers)));
+
+        try {
+            mDnsResolver.setResolverConfiguration(paramsParcel);
+        } catch (RemoteException | ServiceSpecificException e) {
+            Log.e(TAG, "Error setting DNS configuration: " + e);
+            return;
+        }
+    }
+
+    /**
+     * Flush DNS caches and events work before boot has completed.
+     */
+    public void flushVmDnsCache() {
+        /*
+         * Tell the VMs to toss their DNS caches
+         */
+        final Intent intent = new Intent(ConnectivityManager.ACTION_CLEAR_DNS_CACHE);
+        intent.addFlags(Intent.FLAG_RECEIVER_REPLACE_PENDING);
+        /*
+         * Connectivity events can happen before boot has completed ...
+         */
+        intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            mContext.sendBroadcastAsUser(intent, UserHandle.ALL);
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+    }
+
+    private void updateParametersSettings() {
+        mSampleValidity = getIntSetting(
+                DNS_RESOLVER_SAMPLE_VALIDITY_SECONDS,
+                DNS_RESOLVER_DEFAULT_SAMPLE_VALIDITY_SECONDS);
+        if (mSampleValidity < 0 || mSampleValidity > 65535) {
+            Log.w(TAG, "Invalid sampleValidity=" + mSampleValidity + ", using default="
+                    + DNS_RESOLVER_DEFAULT_SAMPLE_VALIDITY_SECONDS);
+            mSampleValidity = DNS_RESOLVER_DEFAULT_SAMPLE_VALIDITY_SECONDS;
+        }
+
+        mSuccessThreshold = getIntSetting(
+                DNS_RESOLVER_SUCCESS_THRESHOLD_PERCENT,
+                DNS_RESOLVER_DEFAULT_SUCCESS_THRESHOLD_PERCENT);
+        if (mSuccessThreshold < 0 || mSuccessThreshold > 100) {
+            Log.w(TAG, "Invalid successThreshold=" + mSuccessThreshold + ", using default="
+                    + DNS_RESOLVER_DEFAULT_SUCCESS_THRESHOLD_PERCENT);
+            mSuccessThreshold = DNS_RESOLVER_DEFAULT_SUCCESS_THRESHOLD_PERCENT;
+        }
+
+        mMinSamples = getIntSetting(DNS_RESOLVER_MIN_SAMPLES, DNS_RESOLVER_DEFAULT_MIN_SAMPLES);
+        mMaxSamples = getIntSetting(DNS_RESOLVER_MAX_SAMPLES, DNS_RESOLVER_DEFAULT_MAX_SAMPLES);
+        if (mMinSamples < 0 || mMinSamples > mMaxSamples || mMaxSamples > 64) {
+            Log.w(TAG, "Invalid sample count (min, max)=(" + mMinSamples + ", " + mMaxSamples
+                    + "), using default=(" + DNS_RESOLVER_DEFAULT_MIN_SAMPLES + ", "
+                    + DNS_RESOLVER_DEFAULT_MAX_SAMPLES + ")");
+            mMinSamples = DNS_RESOLVER_DEFAULT_MIN_SAMPLES;
+            mMaxSamples = DNS_RESOLVER_DEFAULT_MAX_SAMPLES;
+        }
+    }
+
+    private int getIntSetting(String which, int dflt) {
+        return Settings.Global.getInt(mContentResolver, which, dflt);
+    }
+
+    /**
+     * Create a string array of host addresses from a collection of InetAddresses
+     *
+     * @param addrs a Collection of InetAddresses
+     * @return an array of Strings containing their host addresses
+     */
+    private String[] makeStrings(Collection<InetAddress> addrs) {
+        String[] result = new String[addrs.size()];
+        int i = 0;
+        for (InetAddress addr : addrs) {
+            result[i++] = addr.getHostAddress();
+        }
+        return result;
+    }
+
+    private static String getStringSetting(ContentResolver cr, String which) {
+        return Settings.Global.getString(cr, which);
+    }
+
+    private static String[] getDomainStrings(String domains) {
+        return (TextUtils.isEmpty(domains)) ? new String[0] : domains.split(" ");
+    }
+}
diff --git a/service/src/com/android/server/connectivity/FullScore.java b/service/src/com/android/server/connectivity/FullScore.java
new file mode 100644
index 0000000..fbfa7a1
--- /dev/null
+++ b/service/src/com/android/server/connectivity/FullScore.java
@@ -0,0 +1,344 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_METERED;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_VALIDATED;
+import static android.net.NetworkCapabilities.TRANSPORT_VPN;
+import static android.net.NetworkScore.KEEP_CONNECTED_NONE;
+import static android.net.NetworkScore.POLICY_EXITING;
+import static android.net.NetworkScore.POLICY_TRANSPORT_PRIMARY;
+import static android.net.NetworkScore.POLICY_YIELD_TO_BAD_WIFI;
+
+import android.annotation.IntDef;
+import android.annotation.NonNull;
+import android.net.NetworkAgentConfig;
+import android.net.NetworkCapabilities;
+import android.net.NetworkScore;
+import android.net.NetworkScore.KeepConnectedReason;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.util.StringJoiner;
+
+/**
+ * This class represents how desirable a network is.
+ *
+ * FullScore is very similar to NetworkScore, but it contains the bits that are managed
+ * by ConnectivityService. This provides static guarantee that all users must know whether
+ * they are handling a score that had the CS-managed bits set.
+ */
+public class FullScore {
+    // This will be removed soon. Do *NOT* depend on it for any new code that is not part of
+    // a migration.
+    private final int mLegacyInt;
+
+    /** @hide */
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef(prefix = {"POLICY_"}, value = {
+            POLICY_IS_VALIDATED,
+            POLICY_IS_VPN,
+            POLICY_EVER_USER_SELECTED,
+            POLICY_ACCEPT_UNVALIDATED,
+            POLICY_IS_UNMETERED
+    })
+    public @interface Policy {
+    }
+
+    // Agent-managed policies are in NetworkScore. They start from 1.
+    // CS-managed policies, counting from 63 downward
+    // This network is validated. CS-managed because the source of truth is in NetworkCapabilities.
+    /** @hide */
+    public static final int POLICY_IS_VALIDATED = 63;
+
+    // This is a VPN and behaves as one for scoring purposes.
+    /** @hide */
+    public static final int POLICY_IS_VPN = 62;
+
+    // This network has been selected by the user manually from settings or a 3rd party app
+    // at least once. {@see NetworkAgentConfig#explicitlySelected}.
+    /** @hide */
+    public static final int POLICY_EVER_USER_SELECTED = 61;
+
+    // The user has indicated in UI that this network should be used even if it doesn't
+    // validate. {@see NetworkAgentConfig#acceptUnvalidated}.
+    /** @hide */
+    public static final int POLICY_ACCEPT_UNVALIDATED = 60;
+
+    // This network is unmetered. {@see NetworkCapabilities.NET_CAPABILITY_NOT_METERED}.
+    /** @hide */
+    public static final int POLICY_IS_UNMETERED = 59;
+
+    // This network is invincible. This is useful for offers until there is an API to listen
+    // to requests.
+    /** @hide */
+    public static final int POLICY_IS_INVINCIBLE = 58;
+
+    // This network has been validated at least once since it was connected, but not explicitly
+    // avoided in UI.
+    // TODO : remove setAvoidUnvalidated and instead disconnect the network when the user
+    // chooses to move away from this network, and remove this flag.
+    /** @hide */
+    public static final int POLICY_EVER_VALIDATED_NOT_AVOIDED_WHEN_BAD = 57;
+
+    // To help iterate when printing
+    @VisibleForTesting
+    static final int MIN_CS_MANAGED_POLICY = POLICY_EVER_VALIDATED_NOT_AVOIDED_WHEN_BAD;
+    @VisibleForTesting
+    static final int MAX_CS_MANAGED_POLICY = POLICY_IS_VALIDATED;
+
+    // Mask for policies in NetworkScore. This should have all bits managed by NetworkScore set
+    // and all bits managed by FullScore unset. As bits are handled from 0 up in NetworkScore and
+    // from 63 down in FullScore, cut at the 32nd bit for simplicity, but change this if some day
+    // there are more than 32 bits handled on either side.
+    // YIELD_TO_BAD_WIFI is temporarily handled by ConnectivityService, but the factory is still
+    // allowed to set it, so that it's possible to transition from handling it in CS to handling
+    // it in the factory.
+    private static final long EXTERNAL_POLICIES_MASK = 0x00000000FFFFFFFFL;
+
+    @VisibleForTesting
+    static @NonNull String policyNameOf(final int policy) {
+        switch (policy) {
+            case POLICY_IS_VALIDATED: return "IS_VALIDATED";
+            case POLICY_IS_VPN: return "IS_VPN";
+            case POLICY_EVER_USER_SELECTED: return "EVER_USER_SELECTED";
+            case POLICY_ACCEPT_UNVALIDATED: return "ACCEPT_UNVALIDATED";
+            case POLICY_IS_UNMETERED: return "IS_UNMETERED";
+            case POLICY_YIELD_TO_BAD_WIFI: return "YIELD_TO_BAD_WIFI";
+            case POLICY_TRANSPORT_PRIMARY: return "TRANSPORT_PRIMARY";
+            case POLICY_EXITING: return "EXITING";
+            case POLICY_IS_INVINCIBLE: return "INVINCIBLE";
+            case POLICY_EVER_VALIDATED_NOT_AVOIDED_WHEN_BAD: return "EVER_VALIDATED";
+        }
+        throw new IllegalArgumentException("Unknown policy : " + policy);
+    }
+
+    // Bitmask of all the policies applied to this score.
+    private final long mPolicies;
+
+    private final int mKeepConnectedReason;
+
+    FullScore(final int legacyInt, final long policies,
+            @KeepConnectedReason final int keepConnectedReason) {
+        mLegacyInt = legacyInt;
+        mPolicies = policies;
+        mKeepConnectedReason = keepConnectedReason;
+    }
+
+    /**
+     * Given a score supplied by the NetworkAgent and CS-managed objects, produce a full score.
+     *
+     * @param score the score supplied by the agent
+     * @param caps the NetworkCapabilities of the network
+     * @param config the NetworkAgentConfig of the network
+     * @param everValidated whether this network has ever validated
+     * @param yieldToBadWiFi whether this network yields to a previously validated wifi gone bad
+     * @return a FullScore that is appropriate to use for ranking.
+     */
+    // TODO : this shouldn't manage bad wifi avoidance – instead this should be done by the
+    // telephony factory, so that it depends on the carrier. For now this is handled by
+    // connectivity for backward compatibility.
+    public static FullScore fromNetworkScore(@NonNull final NetworkScore score,
+            @NonNull final NetworkCapabilities caps, @NonNull final NetworkAgentConfig config,
+            final boolean everValidated, final boolean yieldToBadWiFi) {
+        return withPolicies(score.getLegacyInt(), score.getPolicies(),
+                score.getKeepConnectedReason(),
+                caps.hasCapability(NET_CAPABILITY_VALIDATED),
+                caps.hasTransport(TRANSPORT_VPN),
+                caps.hasCapability(NET_CAPABILITY_NOT_METERED),
+                everValidated,
+                config.explicitlySelected,
+                config.acceptUnvalidated,
+                yieldToBadWiFi,
+                false /* invincible */); // only prospective scores can be invincible
+    }
+
+    /**
+     * Given a score supplied by a NetworkProvider, produce a prospective score for an offer.
+     *
+     * NetworkOffers have score filters that are compared to the scores of actual networks
+     * to see if they could possibly beat the current satisfier. Some things the agent can't
+     * know in advance ; a good example is the validation bit – some networks will validate,
+     * others won't. For comparison purposes, assume the best, so all possibly beneficial
+     * networks will be brought up.
+     *
+     * @param score the score supplied by the agent for this offer
+     * @param caps the capabilities supplied by the agent for this offer
+     * @return a FullScore appropriate for comparing to actual network's scores.
+     */
+    public static FullScore makeProspectiveScore(@NonNull final NetworkScore score,
+            @NonNull final NetworkCapabilities caps) {
+        // If the network offers Internet access, it may validate.
+        final boolean mayValidate = caps.hasCapability(NET_CAPABILITY_INTERNET);
+        // VPN transports are known in advance.
+        final boolean vpn = caps.hasTransport(TRANSPORT_VPN);
+        // Prospective scores are always unmetered, because unmetered networks are stronger
+        // than metered networks, and it's not known in advance whether the network is metered.
+        final boolean unmetered = true;
+        // If the offer may validate, then it should be considered to have validated at some point
+        final boolean everValidated = mayValidate;
+        // The network hasn't been chosen by the user (yet, at least).
+        final boolean everUserSelected = false;
+        // Don't assume the user will accept unvalidated connectivity.
+        final boolean acceptUnvalidated = false;
+        // Don't assume clinging to bad wifi
+        final boolean yieldToBadWiFi = false;
+        // A prospective score is invincible if the legacy int in the filter is over the maximum
+        // score.
+        final boolean invincible = score.getLegacyInt() > NetworkRanker.LEGACY_INT_MAX;
+        return withPolicies(score.getLegacyInt(), score.getPolicies(), KEEP_CONNECTED_NONE,
+                mayValidate, vpn, unmetered, everValidated, everUserSelected, acceptUnvalidated,
+                yieldToBadWiFi, invincible);
+    }
+
+    /**
+     * Return a new score given updated caps and config.
+     *
+     * @param caps the NetworkCapabilities of the network
+     * @param config the NetworkAgentConfig of the network
+     * @return a score with the policies from the arguments reset
+     */
+    // TODO : this shouldn't manage bad wifi avoidance – instead this should be done by the
+    // telephony factory, so that it depends on the carrier. For now this is handled by
+    // connectivity for backward compatibility.
+    public FullScore mixInScore(@NonNull final NetworkCapabilities caps,
+            @NonNull final NetworkAgentConfig config,
+            final boolean everValidated,
+            final boolean yieldToBadWifi) {
+        return withPolicies(mLegacyInt, mPolicies, mKeepConnectedReason,
+                caps.hasCapability(NET_CAPABILITY_VALIDATED),
+                caps.hasTransport(TRANSPORT_VPN),
+                caps.hasCapability(NET_CAPABILITY_NOT_METERED),
+                everValidated,
+                config.explicitlySelected,
+                config.acceptUnvalidated,
+                yieldToBadWifi,
+                false /* invincible */); // only prospective scores can be invincible
+    }
+
+    // TODO : this shouldn't manage bad wifi avoidance – instead this should be done by the
+    // telephony factory, so that it depends on the carrier. For now this is handled by
+    // connectivity for backward compatibility.
+    private static FullScore withPolicies(@NonNull final int legacyInt,
+            final long externalPolicies,
+            @KeepConnectedReason final int keepConnectedReason,
+            final boolean isValidated,
+            final boolean isVpn,
+            final boolean isUnmetered,
+            final boolean everValidated,
+            final boolean everUserSelected,
+            final boolean acceptUnvalidated,
+            final boolean yieldToBadWiFi,
+            final boolean invincible) {
+        return new FullScore(legacyInt, (externalPolicies & EXTERNAL_POLICIES_MASK)
+                | (isValidated       ? 1L << POLICY_IS_VALIDATED : 0)
+                | (isVpn             ? 1L << POLICY_IS_VPN : 0)
+                | (isUnmetered       ? 1L << POLICY_IS_UNMETERED : 0)
+                | (everValidated     ? 1L << POLICY_EVER_VALIDATED_NOT_AVOIDED_WHEN_BAD : 0)
+                | (everUserSelected  ? 1L << POLICY_EVER_USER_SELECTED : 0)
+                | (acceptUnvalidated ? 1L << POLICY_ACCEPT_UNVALIDATED : 0)
+                | (yieldToBadWiFi    ? 1L << POLICY_YIELD_TO_BAD_WIFI : 0)
+                | (invincible        ? 1L << POLICY_IS_INVINCIBLE : 0),
+                keepConnectedReason);
+    }
+
+    /**
+     * Returns this score but validated.
+     */
+    public FullScore asValidated() {
+        return new FullScore(mLegacyInt, mPolicies | (1L << POLICY_IS_VALIDATED),
+                mKeepConnectedReason);
+    }
+
+    /**
+     * For backward compatibility, get the legacy int.
+     * This will be removed before S is published.
+     */
+    public int getLegacyInt() {
+        return getLegacyInt(false /* pretendValidated */);
+    }
+
+    public int getLegacyIntAsValidated() {
+        return getLegacyInt(true /* pretendValidated */);
+    }
+
+    // TODO : remove these two constants
+    // Penalty applied to scores of Networks that have not been validated.
+    private static final int UNVALIDATED_SCORE_PENALTY = 40;
+
+    // Score for a network that can be used unvalidated
+    private static final int ACCEPT_UNVALIDATED_NETWORK_SCORE = 100;
+
+    private int getLegacyInt(boolean pretendValidated) {
+        // If the user has chosen this network at least once, give it the maximum score when
+        // checking to pretend it's validated, or if it doesn't need to validate because the
+        // user said to use it even if it doesn't validate.
+        // This ensures that networks that have been selected in UI are not torn down before the
+        // user gets a chance to prefer it when a higher-scoring network (e.g., Ethernet) is
+        // available.
+        if (hasPolicy(POLICY_EVER_USER_SELECTED)
+                && (hasPolicy(POLICY_ACCEPT_UNVALIDATED) || pretendValidated)) {
+            return ACCEPT_UNVALIDATED_NETWORK_SCORE;
+        }
+
+        int score = mLegacyInt;
+        // Except for VPNs, networks are subject to a penalty for not being validated.
+        // Apply the penalty unless the network is a VPN, or it's validated or pretending to be.
+        if (!hasPolicy(POLICY_IS_VALIDATED) && !pretendValidated && !hasPolicy(POLICY_IS_VPN)) {
+            score -= UNVALIDATED_SCORE_PENALTY;
+        }
+        if (score < 0) score = 0;
+        return score;
+    }
+
+    /**
+     * @return whether this score has a particular policy.
+     */
+    @VisibleForTesting
+    public boolean hasPolicy(final int policy) {
+        return 0 != (mPolicies & (1L << policy));
+    }
+
+    /**
+     * Returns the keep-connected reason, or KEEP_CONNECTED_NONE.
+     */
+    public int getKeepConnectedReason() {
+        return mKeepConnectedReason;
+    }
+
+    // Example output :
+    // Score(50 ; Policies : EVER_USER_SELECTED&IS_VALIDATED)
+    @Override
+    public String toString() {
+        final StringJoiner sj = new StringJoiner(
+                "&", // delimiter
+                "Score(" + mLegacyInt + " ; KeepConnected : " + mKeepConnectedReason
+                        + " ; Policies : ", // prefix
+                ")"); // suffix
+        for (int i = NetworkScore.MIN_AGENT_MANAGED_POLICY;
+                i <= NetworkScore.MAX_AGENT_MANAGED_POLICY; ++i) {
+            if (hasPolicy(i)) sj.add(policyNameOf(i));
+        }
+        for (int i = MIN_CS_MANAGED_POLICY; i <= MAX_CS_MANAGED_POLICY; ++i) {
+            if (hasPolicy(i)) sj.add(policyNameOf(i));
+        }
+        return sj.toString();
+    }
+}
diff --git a/service/src/com/android/server/connectivity/KeepaliveTracker.java b/service/src/com/android/server/connectivity/KeepaliveTracker.java
new file mode 100644
index 0000000..acf39f0
--- /dev/null
+++ b/service/src/com/android/server/connectivity/KeepaliveTracker.java
@@ -0,0 +1,768 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.content.pm.PackageManager.PERMISSION_GRANTED;
+import static android.net.NattSocketKeepalive.NATT_PORT;
+import static android.net.NetworkAgent.CMD_START_SOCKET_KEEPALIVE;
+import static android.net.SocketKeepalive.BINDER_DIED;
+import static android.net.SocketKeepalive.DATA_RECEIVED;
+import static android.net.SocketKeepalive.ERROR_INSUFFICIENT_RESOURCES;
+import static android.net.SocketKeepalive.ERROR_INVALID_INTERVAL;
+import static android.net.SocketKeepalive.ERROR_INVALID_IP_ADDRESS;
+import static android.net.SocketKeepalive.ERROR_INVALID_NETWORK;
+import static android.net.SocketKeepalive.ERROR_INVALID_SOCKET;
+import static android.net.SocketKeepalive.ERROR_NO_SUCH_SLOT;
+import static android.net.SocketKeepalive.ERROR_STOP_REASON_UNINITIALIZED;
+import static android.net.SocketKeepalive.ERROR_UNSUPPORTED;
+import static android.net.SocketKeepalive.MAX_INTERVAL_SEC;
+import static android.net.SocketKeepalive.MIN_INTERVAL_SEC;
+import static android.net.SocketKeepalive.NO_KEEPALIVE;
+import static android.net.SocketKeepalive.SUCCESS;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.content.Context;
+import android.net.ConnectivityResources;
+import android.net.ISocketKeepaliveCallback;
+import android.net.InetAddresses;
+import android.net.InvalidPacketException;
+import android.net.KeepalivePacketData;
+import android.net.NattKeepalivePacketData;
+import android.net.NetworkAgent;
+import android.net.SocketKeepalive.InvalidSocketException;
+import android.net.TcpKeepalivePacketData;
+import android.net.util.KeepaliveUtils;
+import android.os.Binder;
+import android.os.Handler;
+import android.os.IBinder;
+import android.os.Message;
+import android.os.Process;
+import android.os.RemoteException;
+import android.system.ErrnoException;
+import android.system.Os;
+import android.util.Log;
+import android.util.Pair;
+
+import com.android.connectivity.resources.R;
+import com.android.internal.util.IndentingPrintWriter;
+import com.android.net.module.util.HexDump;
+import com.android.net.module.util.IpUtils;
+
+import java.io.FileDescriptor;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.SocketAddress;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+
+/**
+ * Manages socket keepalive requests.
+ *
+ * Provides methods to stop and start keepalive requests, and keeps track of keepalives across all
+ * networks. This class is tightly coupled to ConnectivityService. It is not thread-safe and its
+ * handle* methods must be called only from the ConnectivityService handler thread.
+ */
+public class KeepaliveTracker {
+
+    private static final String TAG = "KeepaliveTracker";
+    private static final boolean DBG = false;
+
+    public static final String PERMISSION = android.Manifest.permission.PACKET_KEEPALIVE_OFFLOAD;
+
+    /** Keeps track of keepalive requests. */
+    private final HashMap <NetworkAgentInfo, HashMap<Integer, KeepaliveInfo>> mKeepalives =
+            new HashMap<> ();
+    private final Handler mConnectivityServiceHandler;
+    @NonNull
+    private final TcpKeepaliveController mTcpController;
+    @NonNull
+    private final Context mContext;
+
+    // Supported keepalive count for each transport type, can be configured through
+    // config_networkSupportedKeepaliveCount. For better error handling, use
+    // {@link getSupportedKeepalivesForNetworkCapabilities} instead of direct access.
+    @NonNull
+    private final int[] mSupportedKeepalives;
+
+    // Reserved privileged keepalive slots per transport. Caller's permission will be enforced if
+    // the number of remaining keepalive slots is less than or equal to the threshold.
+    private final int mReservedPrivilegedSlots;
+
+    // Allowed unprivileged keepalive slots per uid. Caller's permission will be enforced if
+    // the number of remaining keepalive slots is less than or equal to the threshold.
+    private final int mAllowedUnprivilegedSlotsForUid;
+
+    public KeepaliveTracker(Context context, Handler handler) {
+        mConnectivityServiceHandler = handler;
+        mTcpController = new TcpKeepaliveController(handler);
+        mContext = context;
+        mSupportedKeepalives = KeepaliveUtils.getSupportedKeepalives(mContext);
+
+        // TODO (b/183076074): stop reading legacy resources after migrating overlays
+        final int legacyReservedSlots = mContext.getResources().getInteger(
+                mContext.getResources().getIdentifier(
+                        "config_reservedPrivilegedKeepaliveSlots", "integer", "android"));
+        final int legacyAllowedSlots = mContext.getResources().getInteger(
+                mContext.getResources().getIdentifier(
+                        "config_allowedUnprivilegedKeepalivePerUid", "integer", "android"));
+        final ConnectivityResources res = new ConnectivityResources(mContext);
+        mReservedPrivilegedSlots = Math.min(legacyReservedSlots, res.get().getInteger(
+                R.integer.config_reservedPrivilegedKeepaliveSlots));
+        mAllowedUnprivilegedSlotsForUid = Math.min(legacyAllowedSlots, res.get().getInteger(
+                R.integer.config_allowedUnprivilegedKeepalivePerUid));
+    }
+
+    /**
+     * Tracks information about a socket keepalive.
+     *
+     * All information about this keepalive is known at construction time except the slot number,
+     * which is only returned when the hardware has successfully started the keepalive.
+     */
+    class KeepaliveInfo implements IBinder.DeathRecipient {
+        // Bookkeeping data.
+        private final ISocketKeepaliveCallback mCallback;
+        private final int mUid;
+        private final int mPid;
+        private final boolean mPrivileged;
+        private final NetworkAgentInfo mNai;
+        private final int mType;
+        private final FileDescriptor mFd;
+
+        public static final int TYPE_NATT = 1;
+        public static final int TYPE_TCP = 2;
+
+        // Keepalive slot. A small integer that identifies this keepalive among the ones handled
+        // by this network.
+        private int mSlot = NO_KEEPALIVE;
+
+        // Packet data.
+        private final KeepalivePacketData mPacket;
+        private final int mInterval;
+
+        // Whether the keepalive is started or not. The initial state is NOT_STARTED.
+        private static final int NOT_STARTED = 1;
+        private static final int STARTING = 2;
+        private static final int STARTED = 3;
+        private static final int STOPPING = 4;
+        private int mStartedState = NOT_STARTED;
+        private int mStopReason = ERROR_STOP_REASON_UNINITIALIZED;
+
+        KeepaliveInfo(@NonNull ISocketKeepaliveCallback callback,
+                @NonNull NetworkAgentInfo nai,
+                @NonNull KeepalivePacketData packet,
+                int interval,
+                int type,
+                @Nullable FileDescriptor fd) throws InvalidSocketException {
+            mCallback = callback;
+            mPid = Binder.getCallingPid();
+            mUid = Binder.getCallingUid();
+            mPrivileged = (PERMISSION_GRANTED == mContext.checkPermission(PERMISSION, mPid, mUid));
+
+            mNai = nai;
+            mPacket = packet;
+            mInterval = interval;
+            mType = type;
+
+            // For SocketKeepalive, a dup of fd is kept in mFd so the source port from which the
+            // keepalives are sent cannot be reused by another app even if the fd gets closed by
+            // the user. A null is acceptable here for backward compatibility of PacketKeepalive
+            // API.
+            try {
+                if (fd != null) {
+                    mFd = Os.dup(fd);
+                }  else {
+                    Log.d(TAG, toString() + " calls with null fd");
+                    if (!mPrivileged) {
+                        throw new SecurityException(
+                                "null fd is not allowed for unprivileged access.");
+                    }
+                    if (mType == TYPE_TCP) {
+                        throw new IllegalArgumentException(
+                                "null fd is not allowed for tcp socket keepalives.");
+                    }
+                    mFd = null;
+                }
+            } catch (ErrnoException e) {
+                Log.e(TAG, "Cannot dup fd: ", e);
+                throw new InvalidSocketException(ERROR_INVALID_SOCKET, e);
+            }
+
+            try {
+                mCallback.asBinder().linkToDeath(this, 0);
+            } catch (RemoteException e) {
+                binderDied();
+            }
+        }
+
+        public NetworkAgentInfo getNai() {
+            return mNai;
+        }
+
+        private String startedStateString(final int state) {
+            switch (state) {
+                case NOT_STARTED : return "NOT_STARTED";
+                case STARTING : return "STARTING";
+                case STARTED : return "STARTED";
+                case STOPPING : return "STOPPING";
+            }
+            throw new IllegalArgumentException("Unknown state");
+        }
+
+        public String toString() {
+            return "KeepaliveInfo ["
+                    + " type=" + mType
+                    + " network=" + mNai.network
+                    + " startedState=" + startedStateString(mStartedState)
+                    + " "
+                    + IpUtils.addressAndPortToString(mPacket.getSrcAddress(), mPacket.getSrcPort())
+                    + "->"
+                    + IpUtils.addressAndPortToString(mPacket.getDstAddress(), mPacket.getDstPort())
+                    + " interval=" + mInterval
+                    + " uid=" + mUid + " pid=" + mPid + " privileged=" + mPrivileged
+                    + " packetData=" + HexDump.toHexString(mPacket.getPacket())
+                    + " ]";
+        }
+
+        /** Called when the application process is killed. */
+        public void binderDied() {
+            stop(BINDER_DIED);
+        }
+
+        void unlinkDeathRecipient() {
+            if (mCallback != null) {
+                mCallback.asBinder().unlinkToDeath(this, 0);
+            }
+        }
+
+        private int checkNetworkConnected() {
+            if (!mNai.networkInfo.isConnectedOrConnecting()) {
+                return ERROR_INVALID_NETWORK;
+            }
+            return SUCCESS;
+        }
+
+        private int checkSourceAddress() {
+            // Check that we have the source address.
+            for (InetAddress address : mNai.linkProperties.getAddresses()) {
+                if (address.equals(mPacket.getSrcAddress())) {
+                    return SUCCESS;
+                }
+            }
+            return ERROR_INVALID_IP_ADDRESS;
+        }
+
+        private int checkInterval() {
+            if (mInterval < MIN_INTERVAL_SEC || mInterval > MAX_INTERVAL_SEC) {
+                return ERROR_INVALID_INTERVAL;
+            }
+            return SUCCESS;
+        }
+
+        private int checkPermission() {
+            final HashMap<Integer, KeepaliveInfo> networkKeepalives = mKeepalives.get(mNai);
+            if (networkKeepalives == null) {
+                return ERROR_INVALID_NETWORK;
+            }
+
+            if (mPrivileged) return SUCCESS;
+
+            final int supported = KeepaliveUtils.getSupportedKeepalivesForNetworkCapabilities(
+                    mSupportedKeepalives, mNai.networkCapabilities);
+
+            int takenUnprivilegedSlots = 0;
+            for (final KeepaliveInfo ki : networkKeepalives.values()) {
+                if (!ki.mPrivileged) ++takenUnprivilegedSlots;
+            }
+            if (takenUnprivilegedSlots > supported - mReservedPrivilegedSlots) {
+                return ERROR_INSUFFICIENT_RESOURCES;
+            }
+
+            // Count unprivileged keepalives for the same uid across networks.
+            int unprivilegedCountSameUid = 0;
+            for (final HashMap<Integer, KeepaliveInfo> kaForNetwork : mKeepalives.values()) {
+                for (final KeepaliveInfo ki : kaForNetwork.values()) {
+                    if (ki.mUid == mUid) {
+                        unprivilegedCountSameUid++;
+                    }
+                }
+            }
+            if (unprivilegedCountSameUid > mAllowedUnprivilegedSlotsForUid) {
+                return ERROR_INSUFFICIENT_RESOURCES;
+            }
+            return SUCCESS;
+        }
+
+        private int checkLimit() {
+            final HashMap<Integer, KeepaliveInfo> networkKeepalives = mKeepalives.get(mNai);
+            if (networkKeepalives == null) {
+                return ERROR_INVALID_NETWORK;
+            }
+            final int supported = KeepaliveUtils.getSupportedKeepalivesForNetworkCapabilities(
+                    mSupportedKeepalives, mNai.networkCapabilities);
+            if (supported == 0) return ERROR_UNSUPPORTED;
+            if (networkKeepalives.size() > supported) return ERROR_INSUFFICIENT_RESOURCES;
+            return SUCCESS;
+        }
+
+        private int isValid() {
+            synchronized (mNai) {
+                int error = checkInterval();
+                if (error == SUCCESS) error = checkLimit();
+                if (error == SUCCESS) error = checkPermission();
+                if (error == SUCCESS) error = checkNetworkConnected();
+                if (error == SUCCESS) error = checkSourceAddress();
+                return error;
+            }
+        }
+
+        void start(int slot) {
+            mSlot = slot;
+            int error = isValid();
+            if (error == SUCCESS) {
+                Log.d(TAG, "Starting keepalive " + mSlot + " on " + mNai.toShortString());
+                switch (mType) {
+                    case TYPE_NATT:
+                        final NattKeepalivePacketData nattData = (NattKeepalivePacketData) mPacket;
+                        mNai.onAddNattKeepalivePacketFilter(slot, nattData);
+                        mNai.onStartNattSocketKeepalive(slot, mInterval, nattData);
+                        break;
+                    case TYPE_TCP:
+                        try {
+                            mTcpController.startSocketMonitor(mFd, this, mSlot);
+                        } catch (InvalidSocketException e) {
+                            handleStopKeepalive(mNai, mSlot, ERROR_INVALID_SOCKET);
+                            return;
+                        }
+                        final TcpKeepalivePacketData tcpData = (TcpKeepalivePacketData) mPacket;
+                        mNai.onAddTcpKeepalivePacketFilter(slot, tcpData);
+                        // TODO: check result from apf and notify of failure as needed.
+                        mNai.onStartTcpSocketKeepalive(slot, mInterval, tcpData);
+                        break;
+                    default:
+                        Log.wtf(TAG, "Starting keepalive with unknown type: " + mType);
+                        handleStopKeepalive(mNai, mSlot, error);
+                        return;
+                }
+                mStartedState = STARTING;
+            } else {
+                handleStopKeepalive(mNai, mSlot, error);
+                return;
+            }
+        }
+
+        void stop(int reason) {
+            int uid = Binder.getCallingUid();
+            if (uid != mUid && uid != Process.SYSTEM_UID) {
+                if (DBG) {
+                    Log.e(TAG, "Cannot stop unowned keepalive " + mSlot + " on " + mNai.network);
+                }
+            }
+            // Ignore the case when the network disconnects immediately after stop() has been
+            // called and the keepalive code is waiting for the response from the modem. This
+            // might happen when the caller listens for a lower-layer network disconnect
+            // callback and stop the keepalive at that time. But the stop() races with the
+            // stop() generated in ConnectivityService network disconnection code path.
+            if (mStartedState == STOPPING && reason == ERROR_INVALID_NETWORK) return;
+
+            // Store the reason of stopping, and report it after the keepalive is fully stopped.
+            if (mStopReason != ERROR_STOP_REASON_UNINITIALIZED) {
+                throw new IllegalStateException("Unexpected stop reason: " + mStopReason);
+            }
+            mStopReason = reason;
+            Log.d(TAG, "Stopping keepalive " + mSlot + " on " + mNai.toShortString()
+                    + ": " + reason);
+            switch (mStartedState) {
+                case NOT_STARTED:
+                    // Remove the reference of the keepalive that meet error before starting,
+                    // e.g. invalid parameter.
+                    cleanupStoppedKeepalive(mNai, mSlot);
+                    break;
+                default:
+                    mStartedState = STOPPING;
+                    switch (mType) {
+                        case TYPE_TCP:
+                            mTcpController.stopSocketMonitor(mSlot);
+                            // fall through
+                        case TYPE_NATT:
+                            mNai.onStopSocketKeepalive(mSlot);
+                            mNai.onRemoveKeepalivePacketFilter(mSlot);
+                            break;
+                        default:
+                            Log.wtf(TAG, "Stopping keepalive with unknown type: " + mType);
+                    }
+            }
+
+            // Close the duplicated fd that maintains the lifecycle of socket whenever
+            // keepalive is running.
+            if (mFd != null) {
+                try {
+                    Os.close(mFd);
+                } catch (ErrnoException e) {
+                    // This should not happen since system server controls the lifecycle of fd when
+                    // keepalive offload is running.
+                    Log.wtf(TAG, "Error closing fd for keepalive " + mSlot + ": " + e);
+                }
+            }
+        }
+
+        void onFileDescriptorInitiatedStop(final int socketKeepaliveReason) {
+            handleStopKeepalive(mNai, mSlot, socketKeepaliveReason);
+        }
+    }
+
+    void notifyErrorCallback(ISocketKeepaliveCallback cb, int error) {
+        if (DBG) Log.w(TAG, "Sending onError(" + error + ") callback");
+        try {
+            cb.onError(error);
+        } catch (RemoteException e) {
+            Log.w(TAG, "Discarded onError(" + error + ") callback");
+        }
+    }
+
+    private  int findFirstFreeSlot(NetworkAgentInfo nai) {
+        HashMap networkKeepalives = mKeepalives.get(nai);
+        if (networkKeepalives == null) {
+            networkKeepalives = new HashMap<Integer, KeepaliveInfo>();
+            mKeepalives.put(nai, networkKeepalives);
+        }
+
+        // Find the lowest-numbered free slot. Slot numbers start from 1, because that's what two
+        // separate chipset implementations independently came up with.
+        int slot;
+        for (slot = 1; slot <= networkKeepalives.size(); slot++) {
+            if (networkKeepalives.get(slot) == null) {
+                return slot;
+            }
+        }
+        return slot;
+    }
+
+    public void handleStartKeepalive(Message message) {
+        KeepaliveInfo ki = (KeepaliveInfo) message.obj;
+        NetworkAgentInfo nai = ki.getNai();
+        int slot = findFirstFreeSlot(nai);
+        mKeepalives.get(nai).put(slot, ki);
+        ki.start(slot);
+    }
+
+    public void handleStopAllKeepalives(NetworkAgentInfo nai, int reason) {
+        final HashMap<Integer, KeepaliveInfo> networkKeepalives = mKeepalives.get(nai);
+        if (networkKeepalives != null) {
+            final ArrayList<KeepaliveInfo> kalist = new ArrayList(networkKeepalives.values());
+            for (KeepaliveInfo ki : kalist) {
+                ki.stop(reason);
+                // Clean up keepalives since the network agent is disconnected and unable to pass
+                // back asynchronous result of stop().
+                cleanupStoppedKeepalive(nai, ki.mSlot);
+            }
+        }
+    }
+
+    public void handleStopKeepalive(NetworkAgentInfo nai, int slot, int reason) {
+        final String networkName = NetworkAgentInfo.toShortString(nai);
+        HashMap <Integer, KeepaliveInfo> networkKeepalives = mKeepalives.get(nai);
+        if (networkKeepalives == null) {
+            Log.e(TAG, "Attempt to stop keepalive on nonexistent network " + networkName);
+            return;
+        }
+        KeepaliveInfo ki = networkKeepalives.get(slot);
+        if (ki == null) {
+            Log.e(TAG, "Attempt to stop nonexistent keepalive " + slot + " on " + networkName);
+            return;
+        }
+        ki.stop(reason);
+        // Clean up keepalives will be done as a result of calling ki.stop() after the slots are
+        // freed.
+    }
+
+    private void cleanupStoppedKeepalive(NetworkAgentInfo nai, int slot) {
+        final String networkName = NetworkAgentInfo.toShortString(nai);
+        HashMap<Integer, KeepaliveInfo> networkKeepalives = mKeepalives.get(nai);
+        if (networkKeepalives == null) {
+            Log.e(TAG, "Attempt to remove keepalive on nonexistent network " + networkName);
+            return;
+        }
+        KeepaliveInfo ki = networkKeepalives.get(slot);
+        if (ki == null) {
+            Log.e(TAG, "Attempt to remove nonexistent keepalive " + slot + " on " + networkName);
+            return;
+        }
+
+        // Remove the keepalive from hash table so the slot can be considered available when reusing
+        // it.
+        networkKeepalives.remove(slot);
+        Log.d(TAG, "Remove keepalive " + slot + " on " + networkName + ", "
+                + networkKeepalives.size() + " remains.");
+        if (networkKeepalives.isEmpty()) {
+            mKeepalives.remove(nai);
+        }
+
+        // Notify app that the keepalive is stopped.
+        final int reason = ki.mStopReason;
+        if (reason == SUCCESS) {
+            try {
+                ki.mCallback.onStopped();
+            } catch (RemoteException e) {
+                Log.w(TAG, "Discarded onStop callback: " + reason);
+            }
+        } else if (reason == DATA_RECEIVED) {
+            try {
+                ki.mCallback.onDataReceived();
+            } catch (RemoteException e) {
+                Log.w(TAG, "Discarded onDataReceived callback: " + reason);
+            }
+        } else if (reason == ERROR_STOP_REASON_UNINITIALIZED) {
+            throw new IllegalStateException("Unexpected stop reason: " + reason);
+        } else if (reason == ERROR_NO_SUCH_SLOT) {
+            throw new IllegalStateException("No such slot: " + reason);
+        } else {
+            notifyErrorCallback(ki.mCallback, reason);
+        }
+
+        ki.unlinkDeathRecipient();
+    }
+
+    public void handleCheckKeepalivesStillValid(NetworkAgentInfo nai) {
+        HashMap <Integer, KeepaliveInfo> networkKeepalives = mKeepalives.get(nai);
+        if (networkKeepalives != null) {
+            ArrayList<Pair<Integer, Integer>> invalidKeepalives = new ArrayList<>();
+            for (int slot : networkKeepalives.keySet()) {
+                int error = networkKeepalives.get(slot).isValid();
+                if (error != SUCCESS) {
+                    invalidKeepalives.add(Pair.create(slot, error));
+                }
+            }
+            for (Pair<Integer, Integer> slotAndError: invalidKeepalives) {
+                handleStopKeepalive(nai, slotAndError.first, slotAndError.second);
+            }
+        }
+    }
+
+    /** Handle keepalive events from lower layer. */
+    public void handleEventSocketKeepalive(@NonNull NetworkAgentInfo nai, int slot, int reason) {
+        KeepaliveInfo ki = null;
+        try {
+            ki = mKeepalives.get(nai).get(slot);
+        } catch(NullPointerException e) {}
+        if (ki == null) {
+            Log.e(TAG, "Event " + NetworkAgent.EVENT_SOCKET_KEEPALIVE + "," + slot + "," + reason
+                    + " for unknown keepalive " + slot + " on " + nai.toShortString());
+            return;
+        }
+
+        // This can be called in a number of situations :
+        // - startedState is STARTING.
+        //   - reason is SUCCESS => go to STARTED.
+        //   - reason isn't SUCCESS => it's an error starting. Go to NOT_STARTED and stop keepalive.
+        // - startedState is STARTED.
+        //   - reason is SUCCESS => it's a success stopping. Go to NOT_STARTED and stop keepalive.
+        //   - reason isn't SUCCESS => it's an error in exec. Go to NOT_STARTED and stop keepalive.
+        // The control is not supposed to ever come here if the state is NOT_STARTED. This is
+        // because in NOT_STARTED state, the code will switch to STARTING before sending messages
+        // to start, and the only way to NOT_STARTED is this function, through the edges outlined
+        // above : in all cases, keepalive gets stopped and can't restart without going into
+        // STARTING as messages are ordered. This also depends on the hardware processing the
+        // messages in order.
+        // TODO : clarify this code and get rid of mStartedState. Using a StateMachine is an
+        // option.
+        if (KeepaliveInfo.STARTING == ki.mStartedState) {
+            if (SUCCESS == reason) {
+                // Keepalive successfully started.
+                Log.d(TAG, "Started keepalive " + slot + " on " + nai.toShortString());
+                ki.mStartedState = KeepaliveInfo.STARTED;
+                try {
+                    ki.mCallback.onStarted(slot);
+                } catch (RemoteException e) {
+                    Log.w(TAG, "Discarded onStarted(" + slot + ") callback");
+                }
+            } else {
+                Log.d(TAG, "Failed to start keepalive " + slot + " on " + nai.toShortString()
+                        + ": " + reason);
+                // The message indicated some error trying to start: do call handleStopKeepalive.
+                handleStopKeepalive(nai, slot, reason);
+            }
+        } else if (KeepaliveInfo.STOPPING == ki.mStartedState) {
+            // The message indicated result of stopping : clean up keepalive slots.
+            Log.d(TAG, "Stopped keepalive " + slot + " on " + nai.toShortString()
+                    + " stopped: " + reason);
+            ki.mStartedState = KeepaliveInfo.NOT_STARTED;
+            cleanupStoppedKeepalive(nai, slot);
+        } else {
+            Log.wtf(TAG, "Event " + NetworkAgent.EVENT_SOCKET_KEEPALIVE + "," + slot + "," + reason
+                    + " for keepalive in wrong state: " + ki.toString());
+        }
+    }
+
+    /**
+     * Called when requesting that keepalives be started on a IPsec NAT-T socket. See
+     * {@link android.net.SocketKeepalive}.
+     **/
+    public void startNattKeepalive(@Nullable NetworkAgentInfo nai,
+            @Nullable FileDescriptor fd,
+            int intervalSeconds,
+            @NonNull ISocketKeepaliveCallback cb,
+            @NonNull String srcAddrString,
+            int srcPort,
+            @NonNull String dstAddrString,
+            int dstPort) {
+        if (nai == null) {
+            notifyErrorCallback(cb, ERROR_INVALID_NETWORK);
+            return;
+        }
+
+        InetAddress srcAddress, dstAddress;
+        try {
+            srcAddress = InetAddresses.parseNumericAddress(srcAddrString);
+            dstAddress = InetAddresses.parseNumericAddress(dstAddrString);
+        } catch (IllegalArgumentException e) {
+            notifyErrorCallback(cb, ERROR_INVALID_IP_ADDRESS);
+            return;
+        }
+
+        KeepalivePacketData packet;
+        try {
+            packet = NattKeepalivePacketData.nattKeepalivePacket(
+                    srcAddress, srcPort, dstAddress, NATT_PORT);
+        } catch (InvalidPacketException e) {
+            notifyErrorCallback(cb, e.getError());
+            return;
+        }
+        KeepaliveInfo ki = null;
+        try {
+            ki = new KeepaliveInfo(cb, nai, packet, intervalSeconds,
+                    KeepaliveInfo.TYPE_NATT, fd);
+        } catch (InvalidSocketException | IllegalArgumentException | SecurityException e) {
+            Log.e(TAG, "Fail to construct keepalive", e);
+            notifyErrorCallback(cb, ERROR_INVALID_SOCKET);
+            return;
+        }
+        Log.d(TAG, "Created keepalive: " + ki.toString());
+        mConnectivityServiceHandler.obtainMessage(
+                NetworkAgent.CMD_START_SOCKET_KEEPALIVE, ki).sendToTarget();
+    }
+
+    /**
+     * Called by ConnectivityService to start TCP keepalive on a file descriptor.
+     *
+     * In order to offload keepalive for application correctly, sequence number, ack number and
+     * other fields are needed to form the keepalive packet. Thus, this function synchronously
+     * puts the socket into repair mode to get the necessary information. After the socket has been
+     * put into repair mode, the application cannot access the socket until reverted to normal.
+     *
+     * See {@link android.net.SocketKeepalive}.
+     **/
+    public void startTcpKeepalive(@Nullable NetworkAgentInfo nai,
+            @NonNull FileDescriptor fd,
+            int intervalSeconds,
+            @NonNull ISocketKeepaliveCallback cb) {
+        if (nai == null) {
+            notifyErrorCallback(cb, ERROR_INVALID_NETWORK);
+            return;
+        }
+
+        final TcpKeepalivePacketData packet;
+        try {
+            packet = TcpKeepaliveController.getTcpKeepalivePacket(fd);
+        } catch (InvalidSocketException e) {
+            notifyErrorCallback(cb, e.error);
+            return;
+        } catch (InvalidPacketException e) {
+            notifyErrorCallback(cb, e.getError());
+            return;
+        }
+        KeepaliveInfo ki = null;
+        try {
+            ki = new KeepaliveInfo(cb, nai, packet, intervalSeconds,
+                    KeepaliveInfo.TYPE_TCP, fd);
+        } catch (InvalidSocketException | IllegalArgumentException | SecurityException e) {
+            Log.e(TAG, "Fail to construct keepalive e=" + e);
+            notifyErrorCallback(cb, ERROR_INVALID_SOCKET);
+            return;
+        }
+        Log.d(TAG, "Created keepalive: " + ki.toString());
+        mConnectivityServiceHandler.obtainMessage(CMD_START_SOCKET_KEEPALIVE, ki).sendToTarget();
+    }
+
+   /**
+    * Called when requesting that keepalives be started on a IPsec NAT-T socket. This function is
+    * identical to {@link #startNattKeepalive}, but also takes a {@code resourceId}, which is the
+    * resource index bound to the {@link UdpEncapsulationSocket} when creating by
+    * {@link com.android.server.IpSecService} to verify whether the given
+    * {@link UdpEncapsulationSocket} is legitimate.
+    **/
+    public void startNattKeepalive(@Nullable NetworkAgentInfo nai,
+            @Nullable FileDescriptor fd,
+            int resourceId,
+            int intervalSeconds,
+            @NonNull ISocketKeepaliveCallback cb,
+            @NonNull String srcAddrString,
+            @NonNull String dstAddrString,
+            int dstPort) {
+        // Ensure that the socket is created by IpSecService.
+        if (!isNattKeepaliveSocketValid(fd, resourceId)) {
+            notifyErrorCallback(cb, ERROR_INVALID_SOCKET);
+        }
+
+        // Get src port to adopt old API.
+        int srcPort = 0;
+        try {
+            final SocketAddress srcSockAddr = Os.getsockname(fd);
+            srcPort = ((InetSocketAddress) srcSockAddr).getPort();
+        } catch (ErrnoException e) {
+            notifyErrorCallback(cb, ERROR_INVALID_SOCKET);
+        }
+
+        // Forward request to old API.
+        startNattKeepalive(nai, fd, intervalSeconds, cb, srcAddrString, srcPort,
+                dstAddrString, dstPort);
+    }
+
+    /**
+     * Verify if the IPsec NAT-T file descriptor and resource Id hold for IPsec keepalive is valid.
+     **/
+    public static boolean isNattKeepaliveSocketValid(@Nullable FileDescriptor fd, int resourceId) {
+        // TODO: 1. confirm whether the fd is called from system api or created by IpSecService.
+        //       2. If the fd is created from the system api, check that it's bounded. And
+        //          call dup to keep the fd open.
+        //       3. If the fd is created from IpSecService, check if the resource ID is valid. And
+        //          hold the resource needed in IpSecService.
+        if (null == fd) {
+            return false;
+        }
+        return true;
+    }
+
+    public void dump(IndentingPrintWriter pw) {
+        pw.println("Supported Socket keepalives: " + Arrays.toString(mSupportedKeepalives));
+        pw.println("Reserved Privileged keepalives: " + mReservedPrivilegedSlots);
+        pw.println("Allowed Unprivileged keepalives per uid: " + mAllowedUnprivilegedSlotsForUid);
+        pw.println("Socket keepalives:");
+        pw.increaseIndent();
+        for (NetworkAgentInfo nai : mKeepalives.keySet()) {
+            pw.println(nai.toShortString());
+            pw.increaseIndent();
+            for (int slot : mKeepalives.get(nai).keySet()) {
+                KeepaliveInfo ki = mKeepalives.get(nai).get(slot);
+                pw.println(slot + ": " + ki.toString());
+            }
+            pw.decreaseIndent();
+        }
+        pw.decreaseIndent();
+    }
+}
diff --git a/service/src/com/android/server/connectivity/LingerMonitor.java b/service/src/com/android/server/connectivity/LingerMonitor.java
new file mode 100644
index 0000000..032612c
--- /dev/null
+++ b/service/src/com/android/server/connectivity/LingerMonitor.java
@@ -0,0 +1,330 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.net.ConnectivityManager.NETID_UNSET;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.app.PendingIntent;
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.res.Resources;
+import android.net.ConnectivityResources;
+import android.net.NetworkCapabilities;
+import android.os.SystemClock;
+import android.os.UserHandle;
+import android.text.TextUtils;
+import android.text.format.DateUtils;
+import android.util.Log;
+import android.util.SparseArray;
+import android.util.SparseBooleanArray;
+import android.util.SparseIntArray;
+
+import com.android.connectivity.resources.R;
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.util.MessageUtils;
+import com.android.server.connectivity.NetworkNotificationManager.NotificationType;
+
+import java.util.Arrays;
+import java.util.HashMap;
+
+/**
+ * Class that monitors default network linger events and possibly notifies the user of network
+ * switches.
+ *
+ * This class is not thread-safe and all its methods must be called on the ConnectivityService
+ * handler thread.
+ */
+public class LingerMonitor {
+
+    private static final boolean DBG = true;
+    private static final boolean VDBG = false;
+    private static final String TAG = LingerMonitor.class.getSimpleName();
+
+    public static final int DEFAULT_NOTIFICATION_DAILY_LIMIT = 3;
+    public static final long DEFAULT_NOTIFICATION_RATE_LIMIT_MILLIS = DateUtils.MINUTE_IN_MILLIS;
+
+    private static final HashMap<String, Integer> TRANSPORT_NAMES = makeTransportToNameMap();
+    @VisibleForTesting
+    public static final Intent CELLULAR_SETTINGS = new Intent().setComponent(new ComponentName(
+            "com.android.settings", "com.android.settings.Settings$DataUsageSummaryActivity"));
+
+    @VisibleForTesting
+    public static final int NOTIFY_TYPE_NONE         = 0;
+    public static final int NOTIFY_TYPE_NOTIFICATION = 1;
+    public static final int NOTIFY_TYPE_TOAST        = 2;
+
+    private static SparseArray<String> sNotifyTypeNames = MessageUtils.findMessageNames(
+            new Class[] { LingerMonitor.class }, new String[]{ "NOTIFY_TYPE_" });
+
+    private final Context mContext;
+    final Resources mResources;
+    private final NetworkNotificationManager mNotifier;
+    private final int mDailyLimit;
+    private final long mRateLimitMillis;
+
+    private long mFirstNotificationMillis;
+    private long mLastNotificationMillis;
+    private int mNotificationCounter;
+
+    /** Current notifications. Maps the netId we switched away from to the netId we switched to. */
+    private final SparseIntArray mNotifications = new SparseIntArray();
+
+    /** Whether we ever notified that we switched away from a particular network. */
+    private final SparseBooleanArray mEverNotified = new SparseBooleanArray();
+
+    public LingerMonitor(Context context, NetworkNotificationManager notifier,
+            int dailyLimit, long rateLimitMillis) {
+        mContext = context;
+        mResources = new ConnectivityResources(mContext).get();
+        mNotifier = notifier;
+        mDailyLimit = dailyLimit;
+        mRateLimitMillis = rateLimitMillis;
+        // Ensure that (now - mLastNotificationMillis) >= rateLimitMillis at first
+        mLastNotificationMillis = -rateLimitMillis;
+    }
+
+    private static HashMap<String, Integer> makeTransportToNameMap() {
+        SparseArray<String> numberToName = MessageUtils.findMessageNames(
+            new Class[] { NetworkCapabilities.class }, new String[]{ "TRANSPORT_" });
+        HashMap<String, Integer> nameToNumber = new HashMap<>();
+        for (int i = 0; i < numberToName.size(); i++) {
+            // MessageUtils will fail to initialize if there are duplicate constant values, so there
+            // are no duplicates here.
+            nameToNumber.put(numberToName.valueAt(i), numberToName.keyAt(i));
+        }
+        return nameToNumber;
+    }
+
+    private static boolean hasTransport(NetworkAgentInfo nai, int transport) {
+        return nai.networkCapabilities.hasTransport(transport);
+    }
+
+    private int getNotificationSource(NetworkAgentInfo toNai) {
+        for (int i = 0; i < mNotifications.size(); i++) {
+            if (mNotifications.valueAt(i) == toNai.network.getNetId()) {
+                return mNotifications.keyAt(i);
+            }
+        }
+        return NETID_UNSET;
+    }
+
+    private boolean everNotified(NetworkAgentInfo nai) {
+        return mEverNotified.get(nai.network.getNetId(), false);
+    }
+
+    @VisibleForTesting
+    public boolean isNotificationEnabled(NetworkAgentInfo fromNai, NetworkAgentInfo toNai) {
+        // TODO: Evaluate moving to CarrierConfigManager.
+        String[] notifySwitches = mResources.getStringArray(R.array.config_networkNotifySwitches);
+
+        if (VDBG) {
+            Log.d(TAG, "Notify on network switches: " + Arrays.toString(notifySwitches));
+        }
+
+        for (String notifySwitch : notifySwitches) {
+            if (TextUtils.isEmpty(notifySwitch)) continue;
+            String[] transports = notifySwitch.split("-", 2);
+            if (transports.length != 2) {
+                Log.e(TAG, "Invalid network switch notification configuration: " + notifySwitch);
+                continue;
+            }
+            int fromTransport = TRANSPORT_NAMES.get("TRANSPORT_" + transports[0]);
+            int toTransport = TRANSPORT_NAMES.get("TRANSPORT_" + transports[1]);
+            if (hasTransport(fromNai, fromTransport) && hasTransport(toNai, toTransport)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private void showNotification(NetworkAgentInfo fromNai, NetworkAgentInfo toNai) {
+        mNotifier.showNotification(fromNai.network.getNetId(), NotificationType.NETWORK_SWITCH,
+                fromNai, toNai, createNotificationIntent(), true);
+    }
+
+    @VisibleForTesting
+    protected PendingIntent createNotificationIntent() {
+        return PendingIntent.getActivity(
+                mContext.createContextAsUser(UserHandle.CURRENT, 0 /* flags */),
+                0 /* requestCode */,
+                CELLULAR_SETTINGS,
+                PendingIntent.FLAG_CANCEL_CURRENT | PendingIntent.FLAG_IMMUTABLE);
+    }
+
+    // Removes any notification that was put up as a result of switching to nai.
+    private void maybeStopNotifying(NetworkAgentInfo nai) {
+        int fromNetId = getNotificationSource(nai);
+        if (fromNetId != NETID_UNSET) {
+            mNotifications.delete(fromNetId);
+            mNotifier.clearNotification(fromNetId);
+            // Toasts can't be deleted.
+        }
+    }
+
+    // Notify the user of a network switch using a notification or a toast.
+    private void notify(NetworkAgentInfo fromNai, NetworkAgentInfo toNai, boolean forceToast) {
+        int notifyType = mResources.getInteger(R.integer.config_networkNotifySwitchType);
+        if (notifyType == NOTIFY_TYPE_NOTIFICATION && forceToast) {
+            notifyType = NOTIFY_TYPE_TOAST;
+        }
+
+        if (VDBG) {
+            Log.d(TAG, "Notify type: " + sNotifyTypeNames.get(notifyType, "" + notifyType));
+        }
+
+        switch (notifyType) {
+            case NOTIFY_TYPE_NONE:
+                return;
+            case NOTIFY_TYPE_NOTIFICATION:
+                showNotification(fromNai, toNai);
+                break;
+            case NOTIFY_TYPE_TOAST:
+                mNotifier.showToast(fromNai, toNai);
+                break;
+            default:
+                Log.e(TAG, "Unknown notify type " + notifyType);
+                return;
+        }
+
+        if (DBG) {
+            Log.d(TAG, "Notifying switch from=" + fromNai.toShortString()
+                    + " to=" + toNai.toShortString()
+                    + " type=" + sNotifyTypeNames.get(notifyType, "unknown(" + notifyType + ")"));
+        }
+
+        mNotifications.put(fromNai.network.getNetId(), toNai.network.getNetId());
+        mEverNotified.put(fromNai.network.getNetId(), true);
+    }
+
+    /**
+     * Put up or dismiss a notification or toast for of a change in the default network if needed.
+     *
+     * Putting up a notification when switching from no network to some network is not supported
+     * and as such this method can't be called with a null |fromNai|. It can be called with a
+     * null |toNai| if there isn't a default network any more.
+     *
+     * @param fromNai switching from this NAI
+     * @param toNai switching to this NAI
+     */
+    // The default network changed from fromNai to toNai due to a change in score.
+    public void noteLingerDefaultNetwork(@NonNull final NetworkAgentInfo fromNai,
+            @Nullable final NetworkAgentInfo toNai) {
+        if (VDBG) {
+            Log.d(TAG, "noteLingerDefaultNetwork from=" + fromNai.toShortString()
+                    + " everValidated=" + fromNai.everValidated
+                    + " lastValidated=" + fromNai.lastValidated
+                    + " to=" + toNai.toShortString());
+        }
+
+        // If we are currently notifying the user because the device switched to fromNai, now that
+        // we are switching away from it we should remove the notification. This includes the case
+        // where we switch back to toNai because its score improved again (e.g., because it regained
+        // Internet access).
+        maybeStopNotifying(fromNai);
+
+        // If the network was simply lost (either because it disconnected or because it stopped
+        // being the default with no replacement), then don't show a notification.
+        if (null == toNai) return;
+
+        // If this network never validated, don't notify. Otherwise, we could do things like:
+        //
+        // 1. Unvalidated wifi connects.
+        // 2. Unvalidated mobile data connects.
+        // 3. Cell validates, and we show a notification.
+        // or:
+        // 1. User connects to wireless printer.
+        // 2. User turns on cellular data.
+        // 3. We show a notification.
+        if (!fromNai.everValidated) return;
+
+        // If this network is a captive portal, don't notify. This cannot happen on initial connect
+        // to a captive portal, because the everValidated check above will fail. However, it can
+        // happen if the captive portal reasserts itself (e.g., because its timeout fires). In that
+        // case, as soon as the captive portal reasserts itself, we'll show a sign-in notification.
+        // We don't want to overwrite that notification with this one; the user has already been
+        // notified, and of the two, the captive portal notification is the more useful one because
+        // it allows the user to sign in to the captive portal. In this case, display a toast
+        // in addition to the captive portal notification.
+        //
+        // Note that if the network we switch to is already up when the captive portal reappears,
+        // this won't work because NetworkMonitor tells ConnectivityService that the network is
+        // unvalidated (causing a switch) before asking it to show the sign in notification. In this
+        // case, the toast won't show and we'll only display the sign in notification. This is the
+        // best we can do at this time.
+        boolean forceToast = fromNai.networkCapabilities.hasCapability(
+                NetworkCapabilities.NET_CAPABILITY_CAPTIVE_PORTAL);
+
+        // Only show the notification once, in order to avoid irritating the user every time.
+        // TODO: should we do this?
+        if (everNotified(fromNai)) {
+            if (VDBG) {
+                Log.d(TAG, "Not notifying handover from " + fromNai.toShortString()
+                        + ", already notified");
+            }
+            return;
+        }
+
+        // Only show the notification if we switched away because a network became unvalidated, not
+        // because its score changed.
+        // TODO: instead of just skipping notification, keep a note of it, and show it if it becomes
+        // unvalidated.
+        if (fromNai.lastValidated) return;
+
+        if (!isNotificationEnabled(fromNai, toNai)) return;
+
+        final long now = SystemClock.elapsedRealtime();
+        if (isRateLimited(now) || isAboveDailyLimit(now)) return;
+
+        notify(fromNai, toNai, forceToast);
+    }
+
+    public void noteDisconnect(NetworkAgentInfo nai) {
+        mNotifications.delete(nai.network.getNetId());
+        mEverNotified.delete(nai.network.getNetId());
+        maybeStopNotifying(nai);
+        // No need to cancel notifications on nai: NetworkMonitor does that on disconnect.
+    }
+
+    private boolean isRateLimited(long now) {
+        final long millisSinceLast = now - mLastNotificationMillis;
+        if (millisSinceLast < mRateLimitMillis) {
+            return true;
+        }
+        mLastNotificationMillis = now;
+        return false;
+    }
+
+    private boolean isAboveDailyLimit(long now) {
+        if (mFirstNotificationMillis == 0) {
+            mFirstNotificationMillis = now;
+        }
+        final long millisSinceFirst = now - mFirstNotificationMillis;
+        if (millisSinceFirst > DateUtils.DAY_IN_MILLIS) {
+            mNotificationCounter = 0;
+            mFirstNotificationMillis = 0;
+        }
+        if (mNotificationCounter >= mDailyLimit) {
+            return true;
+        }
+        mNotificationCounter++;
+        return false;
+    }
+}
diff --git a/service/src/com/android/server/connectivity/MockableSystemProperties.java b/service/src/com/android/server/connectivity/MockableSystemProperties.java
new file mode 100644
index 0000000..a25b89a
--- /dev/null
+++ b/service/src/com/android/server/connectivity/MockableSystemProperties.java
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import android.os.SystemProperties;
+
+public class MockableSystemProperties {
+
+    public String get(String key) {
+        return SystemProperties.get(key);
+    }
+
+    public int getInt(String key, int def) {
+        return SystemProperties.getInt(key, def);
+    }
+
+    public boolean getBoolean(String key, boolean def) {
+        return SystemProperties.getBoolean(key, def);
+    }
+}
diff --git a/service/src/com/android/server/connectivity/Nat464Xlat.java b/service/src/com/android/server/connectivity/Nat464Xlat.java
new file mode 100644
index 0000000..c66a280
--- /dev/null
+++ b/service/src/com/android/server/connectivity/Nat464Xlat.java
@@ -0,0 +1,523 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
+
+import static com.android.net.module.util.CollectionUtils.contains;
+
+import android.annotation.NonNull;
+import android.net.ConnectivityManager;
+import android.net.IDnsResolver;
+import android.net.INetd;
+import android.net.InetAddresses;
+import android.net.InterfaceConfigurationParcel;
+import android.net.IpPrefix;
+import android.net.LinkAddress;
+import android.net.LinkProperties;
+import android.net.NetworkInfo;
+import android.net.RouteInfo;
+import android.os.RemoteException;
+import android.os.ServiceSpecificException;
+import android.util.Log;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.net.module.util.NetworkStackConstants;
+import com.android.server.ConnectivityService;
+
+import java.net.Inet6Address;
+import java.util.Objects;
+
+/**
+ * Class to manage a 464xlat CLAT daemon. Nat464Xlat is not thread safe and should be manipulated
+ * from a consistent and unique thread context. It is the responsibility of ConnectivityService to
+ * call into this class from its own Handler thread.
+ *
+ * @hide
+ */
+public class Nat464Xlat {
+    private static final String TAG = Nat464Xlat.class.getSimpleName();
+
+    // This must match the interface prefix in clatd.c.
+    private static final String CLAT_PREFIX = "v4-";
+
+    // The network types on which we will start clatd,
+    // allowing clat only on networks for which we can support IPv6-only.
+    private static final int[] NETWORK_TYPES = {
+        ConnectivityManager.TYPE_MOBILE,
+        ConnectivityManager.TYPE_WIFI,
+        ConnectivityManager.TYPE_ETHERNET,
+    };
+
+    // The network states in which running clatd is supported.
+    private static final NetworkInfo.State[] NETWORK_STATES = {
+        NetworkInfo.State.CONNECTED,
+        NetworkInfo.State.SUSPENDED,
+    };
+
+    private final IDnsResolver mDnsResolver;
+    private final INetd mNetd;
+
+    // The network we're running on, and its type.
+    private final NetworkAgentInfo mNetwork;
+
+    private enum State {
+        IDLE,         // start() not called. Base iface and stacked iface names are null.
+        DISCOVERING,  // same as IDLE, except prefix discovery in progress.
+        STARTING,     // start() called. Base iface and stacked iface names are known.
+        RUNNING,      // start() called, and the stacked iface is known to be up.
+    }
+
+    /**
+     * NAT64 prefix currently in use. Only valid in STARTING or RUNNING states.
+     * Used, among other things, to avoid updates when switching from a prefix learned from one
+     * source (e.g., RA) to the same prefix learned from another source (e.g., RA).
+     */
+    private IpPrefix mNat64PrefixInUse;
+    /** NAT64 prefix (if any) discovered from DNS via RFC 7050. */
+    private IpPrefix mNat64PrefixFromDns;
+    /** NAT64 prefix (if any) learned from the network via RA. */
+    private IpPrefix mNat64PrefixFromRa;
+    private String mBaseIface;
+    private String mIface;
+    private Inet6Address mIPv6Address;
+    private State mState = State.IDLE;
+
+    private boolean mEnableClatOnCellular;
+    private boolean mPrefixDiscoveryRunning;
+
+    public Nat464Xlat(NetworkAgentInfo nai, INetd netd, IDnsResolver dnsResolver,
+            ConnectivityService.Dependencies deps) {
+        mDnsResolver = dnsResolver;
+        mNetd = netd;
+        mNetwork = nai;
+        mEnableClatOnCellular = deps.getCellular464XlatEnabled();
+    }
+
+    /**
+     * Whether to attempt 464xlat on this network. This is true for an IPv6-only network that is
+     * currently connected and where the NetworkAgent has not disabled 464xlat. It is the signal to
+     * enable NAT64 prefix discovery.
+     *
+     * @param nai the NetworkAgentInfo corresponding to the network.
+     * @return true if the network requires clat, false otherwise.
+     */
+    @VisibleForTesting
+    protected boolean requiresClat(NetworkAgentInfo nai) {
+        // TODO: migrate to NetworkCapabilities.TRANSPORT_*.
+        final boolean supported = contains(NETWORK_TYPES, nai.networkInfo.getType());
+        final boolean connected = contains(NETWORK_STATES, nai.networkInfo.getState());
+
+        // Only run clat on networks that have a global IPv6 address and don't have a native IPv4
+        // address.
+        LinkProperties lp = nai.linkProperties;
+        final boolean isIpv6OnlyNetwork = (lp != null) && lp.hasGlobalIpv6Address()
+                && !lp.hasIpv4Address();
+
+        // If the network tells us it doesn't use clat, respect that.
+        final boolean skip464xlat = (nai.netAgentConfig() != null)
+                && nai.netAgentConfig().skip464xlat;
+
+        return supported && connected && isIpv6OnlyNetwork && !skip464xlat
+            && (nai.networkCapabilities.hasTransport(TRANSPORT_CELLULAR)
+                ? isCellular464XlatEnabled() : true);
+    }
+
+    /**
+     * Whether the clat demon should be started on this network now. This is true if requiresClat is
+     * true and a NAT64 prefix has been discovered.
+     *
+     * @param nai the NetworkAgentInfo corresponding to the network.
+     * @return true if the network should start clat, false otherwise.
+     */
+    @VisibleForTesting
+    protected boolean shouldStartClat(NetworkAgentInfo nai) {
+        LinkProperties lp = nai.linkProperties;
+        return requiresClat(nai) && lp != null && lp.getNat64Prefix() != null;
+    }
+
+    /**
+     * @return true if clatd has been started and has not yet stopped.
+     * A true result corresponds to internal states STARTING and RUNNING.
+     */
+    public boolean isStarted() {
+        return (mState == State.STARTING || mState == State.RUNNING);
+    }
+
+    /**
+     * @return true if clatd has been started but the stacked interface is not yet up.
+     */
+    public boolean isStarting() {
+        return mState == State.STARTING;
+    }
+
+    /**
+     * @return true if clatd has been started and the stacked interface is up.
+     */
+    public boolean isRunning() {
+        return mState == State.RUNNING;
+    }
+
+    /**
+     * Start clatd, register this Nat464Xlat as a network observer for the stacked interface,
+     * and set internal state.
+     */
+    private void enterStartingState(String baseIface) {
+        mNat64PrefixInUse = selectNat64Prefix();
+        String addrStr = null;
+        try {
+            addrStr = mNetd.clatdStart(baseIface, mNat64PrefixInUse.toString());
+        } catch (RemoteException | ServiceSpecificException e) {
+            Log.e(TAG, "Error starting clatd on " + baseIface + ": " + e);
+        }
+        mIface = CLAT_PREFIX + baseIface;
+        mBaseIface = baseIface;
+        mState = State.STARTING;
+        try {
+            mIPv6Address = (Inet6Address) InetAddresses.parseNumericAddress(addrStr);
+        } catch (ClassCastException | IllegalArgumentException | NullPointerException e) {
+            Log.e(TAG, "Invalid IPv6 address " + addrStr);
+        }
+        if (mPrefixDiscoveryRunning && !isPrefixDiscoveryNeeded()) {
+            stopPrefixDiscovery();
+        }
+        if (!mPrefixDiscoveryRunning) {
+            setPrefix64(mNat64PrefixInUse);
+        }
+    }
+
+    /**
+     * Enter running state just after getting confirmation that the stacked interface is up, and
+     * turn ND offload off if on WiFi.
+     */
+    private void enterRunningState() {
+        mState = State.RUNNING;
+    }
+
+    /**
+     * Unregister as a base observer for the stacked interface, and clear internal state.
+     */
+    private void leaveStartedState() {
+        mNat64PrefixInUse = null;
+        mIface = null;
+        mBaseIface = null;
+
+        if (!mPrefixDiscoveryRunning) {
+            setPrefix64(null);
+        }
+
+        if (isPrefixDiscoveryNeeded()) {
+            if (!mPrefixDiscoveryRunning) {
+                startPrefixDiscovery();
+            }
+            mState = State.DISCOVERING;
+        } else {
+            stopPrefixDiscovery();
+            mState = State.IDLE;
+        }
+    }
+
+    @VisibleForTesting
+    protected void start() {
+        if (isStarted()) {
+            Log.e(TAG, "startClat: already started");
+            return;
+        }
+
+        String baseIface = mNetwork.linkProperties.getInterfaceName();
+        if (baseIface == null) {
+            Log.e(TAG, "startClat: Can't start clat on null interface");
+            return;
+        }
+        // TODO: should we only do this if mNetd.clatdStart() succeeds?
+        Log.i(TAG, "Starting clatd on " + baseIface);
+        enterStartingState(baseIface);
+    }
+
+    @VisibleForTesting
+    protected void stop() {
+        if (!isStarted()) {
+            Log.e(TAG, "stopClat: already stopped");
+            return;
+        }
+
+        Log.i(TAG, "Stopping clatd on " + mBaseIface);
+        try {
+            mNetd.clatdStop(mBaseIface);
+        } catch (RemoteException | ServiceSpecificException e) {
+            Log.e(TAG, "Error stopping clatd on " + mBaseIface + ": " + e);
+        }
+
+        String iface = mIface;
+        boolean wasRunning = isRunning();
+
+        // Change state before updating LinkProperties. handleUpdateLinkProperties ends up calling
+        // fixupLinkProperties, and if at that time the state is still RUNNING, fixupLinkProperties
+        // would wrongly inform ConnectivityService that there is still a stacked interface.
+        leaveStartedState();
+
+        if (wasRunning) {
+            LinkProperties lp = new LinkProperties(mNetwork.linkProperties);
+            lp.removeStackedLink(iface);
+            mNetwork.connService().handleUpdateLinkProperties(mNetwork, lp);
+        }
+    }
+
+    private void startPrefixDiscovery() {
+        try {
+            mDnsResolver.startPrefix64Discovery(getNetId());
+        } catch (RemoteException | ServiceSpecificException e) {
+            Log.e(TAG, "Error starting prefix discovery on netId " + getNetId() + ": " + e);
+        }
+        mPrefixDiscoveryRunning = true;
+    }
+
+    private void stopPrefixDiscovery() {
+        try {
+            mDnsResolver.stopPrefix64Discovery(getNetId());
+        } catch (RemoteException | ServiceSpecificException e) {
+            Log.e(TAG, "Error stopping prefix discovery on netId " + getNetId() + ": " + e);
+        }
+        mPrefixDiscoveryRunning = false;
+    }
+
+    private boolean isPrefixDiscoveryNeeded() {
+        // If there is no NAT64 prefix in the RA, prefix discovery is always needed. It cannot be
+        // stopped after it succeeds, because stopping it will cause netd to report that the prefix
+        // has been removed, and that will cause us to stop clatd.
+        return requiresClat(mNetwork) && mNat64PrefixFromRa == null;
+    }
+
+    private void setPrefix64(IpPrefix prefix) {
+        final String prefixString = (prefix != null) ? prefix.toString() : "";
+        try {
+            mDnsResolver.setPrefix64(getNetId(), prefixString);
+        } catch (RemoteException | ServiceSpecificException e) {
+            Log.e(TAG, "Error setting NAT64 prefix on netId " + getNetId() + " to "
+                    + prefix + ": " + e);
+        }
+    }
+
+    private void maybeHandleNat64PrefixChange() {
+        final IpPrefix newPrefix = selectNat64Prefix();
+        if (!Objects.equals(mNat64PrefixInUse, newPrefix)) {
+            Log.d(TAG, "NAT64 prefix changed from " + mNat64PrefixInUse + " to "
+                    + newPrefix);
+            stop();
+            // It's safe to call update here, even though this method is called from update, because
+            // stop() is guaranteed to have moved out of STARTING and RUNNING, which are the only
+            // states in which this method can be called.
+            update();
+        }
+    }
+
+    /**
+     * Starts/stops NAT64 prefix discovery and clatd as necessary.
+     */
+    public void update() {
+        // TODO: turn this class into a proper StateMachine. http://b/126113090
+        switch (mState) {
+            case IDLE:
+                if (isPrefixDiscoveryNeeded()) {
+                    startPrefixDiscovery();  // Enters DISCOVERING state.
+                    mState = State.DISCOVERING;
+                } else if (requiresClat(mNetwork)) {
+                    start();  // Enters STARTING state.
+                }
+                break;
+
+            case DISCOVERING:
+                if (shouldStartClat(mNetwork)) {
+                    // NAT64 prefix detected. Start clatd.
+                    start();  // Enters STARTING state.
+                    return;
+                }
+                if (!requiresClat(mNetwork)) {
+                    // IPv4 address added. Go back to IDLE state.
+                    stopPrefixDiscovery();
+                    mState = State.IDLE;
+                    return;
+                }
+                break;
+
+            case STARTING:
+            case RUNNING:
+                // NAT64 prefix removed, or IPv4 address added.
+                // Stop clatd and go back into DISCOVERING or idle.
+                if (!shouldStartClat(mNetwork)) {
+                    stop();
+                    break;
+                }
+                // Only necessary while clat is actually started.
+                maybeHandleNat64PrefixChange();
+                break;
+        }
+    }
+
+    /**
+     * Picks a NAT64 prefix to use. Always prefers the prefix from the RA if one is received from
+     * both RA and DNS, because the prefix in the RA has better security and updatability, and will
+     * almost always be received first anyway.
+     *
+     * Any network that supports legacy hosts will support discovering the DNS64 prefix via DNS as
+     * well. If the prefix from the RA is withdrawn, fall back to that for reliability purposes.
+     */
+    private IpPrefix selectNat64Prefix() {
+        return mNat64PrefixFromRa != null ? mNat64PrefixFromRa : mNat64PrefixFromDns;
+    }
+
+    public void setNat64PrefixFromRa(IpPrefix prefix) {
+        mNat64PrefixFromRa = prefix;
+    }
+
+    public void setNat64PrefixFromDns(IpPrefix prefix) {
+        mNat64PrefixFromDns = prefix;
+    }
+
+    /**
+     * Copies the stacked clat link in oldLp, if any, to the passed LinkProperties.
+     * This is necessary because the LinkProperties in mNetwork come from the transport layer, which
+     * has no idea that 464xlat is running on top of it.
+     */
+    public void fixupLinkProperties(@NonNull LinkProperties oldLp, @NonNull LinkProperties lp) {
+        // This must be done even if clatd is not running, because otherwise shouldStartClat would
+        // never return true.
+        lp.setNat64Prefix(selectNat64Prefix());
+
+        if (!isRunning()) {
+            return;
+        }
+        if (lp.getAllInterfaceNames().contains(mIface)) {
+            return;
+        }
+
+        Log.d(TAG, "clatd running, updating NAI for " + mIface);
+        for (LinkProperties stacked: oldLp.getStackedLinks()) {
+            if (Objects.equals(mIface, stacked.getInterfaceName())) {
+                lp.addStackedLink(stacked);
+                return;
+            }
+        }
+    }
+
+    private LinkProperties makeLinkProperties(LinkAddress clatAddress) {
+        LinkProperties stacked = new LinkProperties();
+        stacked.setInterfaceName(mIface);
+
+        // Although the clat interface is a point-to-point tunnel, we don't
+        // point the route directly at the interface because some apps don't
+        // understand routes without gateways (see, e.g., http://b/9597256
+        // http://b/9597516). Instead, set the next hop of the route to the
+        // clat IPv4 address itself (for those apps, it doesn't matter what
+        // the IP of the gateway is, only that there is one).
+        RouteInfo ipv4Default = new RouteInfo(
+                new LinkAddress(NetworkStackConstants.IPV4_ADDR_ANY, 0),
+                clatAddress.getAddress(), mIface);
+        stacked.addRoute(ipv4Default);
+        stacked.addLinkAddress(clatAddress);
+        return stacked;
+    }
+
+    private LinkAddress getLinkAddress(String iface) {
+        try {
+            final InterfaceConfigurationParcel config = mNetd.interfaceGetCfg(iface);
+            return new LinkAddress(
+                    InetAddresses.parseNumericAddress(config.ipv4Addr), config.prefixLength);
+        } catch (IllegalArgumentException | RemoteException | ServiceSpecificException e) {
+            Log.e(TAG, "Error getting link properties: " + e);
+            return null;
+        }
+    }
+
+    /**
+     * Adds stacked link on base link and transitions to RUNNING state.
+     */
+    private void handleInterfaceLinkStateChanged(String iface, boolean up) {
+        // TODO: if we call start(), then stop(), then start() again, and the
+        // interfaceLinkStateChanged notification for the first start is delayed past the first
+        // stop, then the code becomes out of sync with system state and will behave incorrectly.
+        //
+        // This is not trivial to fix because:
+        // 1. It is not guaranteed that start() will eventually result in the interface coming up,
+        //    because there could be an error starting clat (e.g., if the interface goes down before
+        //    the packet socket can be bound).
+        // 2. If start is called multiple times, there is nothing in the interfaceLinkStateChanged
+        //    notification that says which start() call the interface was created by.
+        //
+        // Once this code is converted to StateMachine, it will be possible to use deferMessage to
+        // ensure it stays in STARTING state until the interfaceLinkStateChanged notification fires,
+        // and possibly use a timeout (or provide some guarantees at the lower layer) to address #1.
+        if (!isStarting() || !up || !Objects.equals(mIface, iface)) {
+            return;
+        }
+
+        LinkAddress clatAddress = getLinkAddress(iface);
+        if (clatAddress == null) {
+            Log.e(TAG, "clatAddress was null for stacked iface " + iface);
+            return;
+        }
+
+        Log.i(TAG, String.format("interface %s is up, adding stacked link %s on top of %s",
+                mIface, mIface, mBaseIface));
+        enterRunningState();
+        LinkProperties lp = new LinkProperties(mNetwork.linkProperties);
+        lp.addStackedLink(makeLinkProperties(clatAddress));
+        mNetwork.connService().handleUpdateLinkProperties(mNetwork, lp);
+    }
+
+    /**
+     * Removes stacked link on base link and transitions to IDLE state.
+     */
+    private void handleInterfaceRemoved(String iface) {
+        if (!Objects.equals(mIface, iface)) {
+            return;
+        }
+        if (!isRunning()) {
+            return;
+        }
+
+        Log.i(TAG, "interface " + iface + " removed");
+        // If we're running, and the interface was removed, then we didn't call stop(), and it's
+        // likely that clatd crashed. Ensure we call stop() so we can start clatd again. Calling
+        // stop() will also update LinkProperties, and if clatd crashed, the LinkProperties update
+        // will cause ConnectivityService to call start() again.
+        stop();
+    }
+
+    public void interfaceLinkStateChanged(String iface, boolean up) {
+        mNetwork.handler().post(() -> { handleInterfaceLinkStateChanged(iface, up); });
+    }
+
+    public void interfaceRemoved(String iface) {
+        mNetwork.handler().post(() -> handleInterfaceRemoved(iface));
+    }
+
+    @Override
+    public String toString() {
+        return "mBaseIface: " + mBaseIface + ", mIface: " + mIface + ", mState: " + mState;
+    }
+
+    @VisibleForTesting
+    protected int getNetId() {
+        return mNetwork.network.getNetId();
+    }
+
+    @VisibleForTesting
+    protected boolean isCellular464XlatEnabled() {
+        return mEnableClatOnCellular;
+    }
+}
diff --git a/service/src/com/android/server/connectivity/NetworkAgentInfo.java b/service/src/com/android/server/connectivity/NetworkAgentInfo.java
new file mode 100644
index 0000000..18becd4
--- /dev/null
+++ b/service/src/com/android/server/connectivity/NetworkAgentInfo.java
@@ -0,0 +1,1215 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.net.ConnectivityDiagnosticsManager.ConnectivityReport;
+import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
+import static android.net.NetworkCapabilities.transportNamesOf;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.content.Context;
+import android.net.CaptivePortalData;
+import android.net.IDnsResolver;
+import android.net.INetd;
+import android.net.INetworkAgent;
+import android.net.INetworkAgentRegistry;
+import android.net.INetworkMonitor;
+import android.net.LinkProperties;
+import android.net.NattKeepalivePacketData;
+import android.net.Network;
+import android.net.NetworkAgent;
+import android.net.NetworkAgentConfig;
+import android.net.NetworkCapabilities;
+import android.net.NetworkInfo;
+import android.net.NetworkMonitorManager;
+import android.net.NetworkRequest;
+import android.net.NetworkScore;
+import android.net.NetworkStateSnapshot;
+import android.net.QosCallbackException;
+import android.net.QosFilter;
+import android.net.QosFilterParcelable;
+import android.net.QosSession;
+import android.net.TcpKeepalivePacketData;
+import android.os.Handler;
+import android.os.IBinder;
+import android.os.RemoteException;
+import android.os.SystemClock;
+import android.telephony.data.EpsBearerQosSessionAttributes;
+import android.telephony.data.NrQosSessionAttributes;
+import android.util.Log;
+import android.util.Pair;
+import android.util.SparseArray;
+
+import com.android.internal.util.WakeupMessage;
+import com.android.server.ConnectivityService;
+
+import java.io.PrintWriter;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.Objects;
+import java.util.SortedSet;
+import java.util.TreeSet;
+
+/**
+ * A bag class used by ConnectivityService for holding a collection of most recent
+ * information published by a particular NetworkAgent as well as the
+ * AsyncChannel/messenger for reaching that NetworkAgent and lists of NetworkRequests
+ * interested in using it.  Default sort order is descending by score.
+ */
+// States of a network:
+// --------------------
+// 1. registered, uncreated, disconnected, unvalidated
+//    This state is entered when a NetworkFactory registers a NetworkAgent in any state except
+//    the CONNECTED state.
+// 2. registered, uncreated, connecting, unvalidated
+//    This state is entered when a registered NetworkAgent for a VPN network transitions to the
+//    CONNECTING state (TODO: go through this state for every network, not just VPNs).
+//    ConnectivityService will tell netd to create the network early in order to add extra UID
+//    routing rules referencing the netID. These rules need to be in place before the network is
+//    connected to avoid racing against client apps trying to connect to a half-setup network.
+// 3. registered, uncreated, connected, unvalidated
+//    This state is entered when a registered NetworkAgent transitions to the CONNECTED state.
+//    ConnectivityService will tell netd to create the network if it was not already created, and
+//    immediately transition to state #4.
+// 4. registered, created, connected, unvalidated
+//    If this network can satisfy the default NetworkRequest, then NetworkMonitor will
+//    probe for Internet connectivity.
+//    If this network cannot satisfy the default NetworkRequest, it will immediately be
+//    transitioned to state #5.
+//    A network may remain in this state if NetworkMonitor fails to find Internet connectivity,
+//    for example:
+//    a. a captive portal is present, or
+//    b. a WiFi router whose Internet backhaul is down, or
+//    c. a wireless connection stops transfering packets temporarily (e.g. device is in elevator
+//       or tunnel) but does not disconnect from the AP/cell tower, or
+//    d. a stand-alone device offering a WiFi AP without an uplink for configuration purposes.
+// 5. registered, created, connected, validated
+//
+// The device's default network connection:
+// ----------------------------------------
+// Networks in states #4 and #5 may be used as a device's default network connection if they
+// satisfy the default NetworkRequest.
+// A network, that satisfies the default NetworkRequest, in state #5 should always be chosen
+// in favor of a network, that satisfies the default NetworkRequest, in state #4.
+// When deciding between two networks, that both satisfy the default NetworkRequest, to select
+// for the default network connection, the one with the higher score should be chosen.
+//
+// When a network disconnects:
+// ---------------------------
+// If a network's transport disappears, for example:
+// a. WiFi turned off, or
+// b. cellular data turned off, or
+// c. airplane mode is turned on, or
+// d. a wireless connection disconnects from AP/cell tower entirely (e.g. device is out of range
+//    of AP for an extended period of time, or switches to another AP without roaming)
+// then that network can transition from any state (#1-#5) to unregistered.  This happens by
+// the transport disconnecting their NetworkAgent's AsyncChannel with ConnectivityManager.
+// ConnectivityService also tells netd to destroy the network.
+//
+// When ConnectivityService disconnects a network:
+// -----------------------------------------------
+// If a network is just connected, ConnectivityService will think it will be used soon, but might
+// not be used. Thus, a 5s timer will be held to prevent the network being torn down immediately.
+// This "nascent" state is implemented by the "lingering" logic below without relating to any
+// request, and is used in some cases where network requests race with network establishment. The
+// nascent state ends when the 5-second timer fires, or as soon as the network satisfies a
+// request, whichever is earlier. In this state, the network is considered in the background.
+//
+// If a network has no chance of satisfying any requests (even if it were to become validated
+// and enter state #5), ConnectivityService will disconnect the NetworkAgent's AsyncChannel.
+//
+// If the network was satisfying a foreground NetworkRequest (i.e. had been the highest scoring that
+// satisfied the NetworkRequest's constraints), but is no longer the highest scoring network for any
+// foreground NetworkRequest, then there will be a 30s pause to allow network communication to be
+// wrapped up rather than abruptly terminated. During this pause the network is said to be
+// "lingering". During this pause if the network begins satisfying a foreground NetworkRequest,
+// ConnectivityService will cancel the future disconnection of the NetworkAgent's AsyncChannel, and
+// the network is no longer considered "lingering". After the linger timer expires, if the network
+// is satisfying one or more background NetworkRequests it is kept up in the background. If it is
+// not, ConnectivityService disconnects the NetworkAgent's AsyncChannel.
+public class NetworkAgentInfo implements Comparable<NetworkAgentInfo>, NetworkRanker.Scoreable {
+
+    @NonNull public NetworkInfo networkInfo;
+    // This Network object should always be used if possible, so as to encourage reuse of the
+    // enclosed socket factory and connection pool.  Avoid creating other Network objects.
+    // This Network object is always valid.
+    @NonNull public final Network network;
+    @NonNull public LinkProperties linkProperties;
+    // This should only be modified by ConnectivityService, via setNetworkCapabilities().
+    // TODO: make this private with a getter.
+    @NonNull public NetworkCapabilities networkCapabilities;
+    @NonNull public final NetworkAgentConfig networkAgentConfig;
+
+    // Underlying networks declared by the agent. Only set if supportsUnderlyingNetworks is true.
+    // The networks in this list might be declared by a VPN app using setUnderlyingNetworks and are
+    // not guaranteed to be current or correct, or even to exist.
+    //
+    // This array is read and iterated on multiple threads with no locking so its contents must
+    // never be modified. When the list of networks changes, replace with a new array, on the
+    // handler thread.
+    public @Nullable volatile Network[] declaredUnderlyingNetworks;
+
+    // The capabilities originally announced by the NetworkAgent, regardless of any capabilities
+    // that were added or removed due to this network's underlying networks.
+    // Only set if #supportsUnderlyingNetworks is true.
+    public @Nullable NetworkCapabilities declaredCapabilities;
+
+    // Indicates if netd has been told to create this Network. From this point on the appropriate
+    // routing rules are setup and routes are added so packets can begin flowing over the Network.
+    // This is a sticky bit; once set it is never cleared.
+    public boolean created;
+    // Set to true after the first time this network is marked as CONNECTED. Once set, the network
+    // shows up in API calls, is able to satisfy NetworkRequests and can become the default network.
+    // This is a sticky bit; once set it is never cleared.
+    public boolean everConnected;
+    // Set to true if this Network successfully passed validation or if it did not satisfy the
+    // default NetworkRequest in which case validation will not be attempted.
+    // This is a sticky bit; once set it is never cleared even if future validation attempts fail.
+    public boolean everValidated;
+
+    // The result of the last validation attempt on this network (true if validated, false if not).
+    public boolean lastValidated;
+
+    // If true, becoming unvalidated will lower the network's score. This is only meaningful if the
+    // system is configured not to do this for certain networks, e.g., if the
+    // config_networkAvoidBadWifi option is set to 0 and the user has not overridden that via
+    // Settings.Global.NETWORK_AVOID_BAD_WIFI.
+    public boolean avoidUnvalidated;
+
+    // Whether a captive portal was ever detected on this network.
+    // This is a sticky bit; once set it is never cleared.
+    public boolean everCaptivePortalDetected;
+
+    // Whether a captive portal was found during the last network validation attempt.
+    public boolean lastCaptivePortalDetected;
+
+    // Set to true when partial connectivity was detected.
+    public boolean partialConnectivity;
+
+    // Delay between when the network is disconnected and when the native network is destroyed.
+    public int teardownDelayMs;
+
+    // Captive portal info of the network from RFC8908, if any.
+    // Obtained by ConnectivityService and merged into NetworkAgent-provided information.
+    public CaptivePortalData capportApiData;
+
+    // The UID of the remote entity that created this Network.
+    public final int creatorUid;
+
+    // Network agent portal info of the network, if any. This information is provided from
+    // non-RFC8908 sources, such as Wi-Fi Passpoint, which can provide information such as Venue
+    // URL, Terms & Conditions URL, and network friendly name.
+    public CaptivePortalData networkAgentPortalData;
+
+    // Networks are lingered when they become unneeded as a result of their NetworkRequests being
+    // satisfied by a higher-scoring network. so as to allow communication to wrap up before the
+    // network is taken down.  This usually only happens to the default network. Lingering ends with
+    // either the linger timeout expiring and the network being taken down, or the network
+    // satisfying a request again.
+    public static class InactivityTimer implements Comparable<InactivityTimer> {
+        public final int requestId;
+        public final long expiryMs;
+
+        public InactivityTimer(int requestId, long expiryMs) {
+            this.requestId = requestId;
+            this.expiryMs = expiryMs;
+        }
+        public boolean equals(Object o) {
+            if (!(o instanceof InactivityTimer)) return false;
+            InactivityTimer other = (InactivityTimer) o;
+            return (requestId == other.requestId) && (expiryMs == other.expiryMs);
+        }
+        public int hashCode() {
+            return Objects.hash(requestId, expiryMs);
+        }
+        public int compareTo(InactivityTimer other) {
+            return (expiryMs != other.expiryMs) ?
+                    Long.compare(expiryMs, other.expiryMs) :
+                    Integer.compare(requestId, other.requestId);
+        }
+        public String toString() {
+            return String.format("%s, expires %dms", requestId,
+                    expiryMs - SystemClock.elapsedRealtime());
+        }
+    }
+
+    /**
+     * Inform ConnectivityService that the network LINGER period has
+     * expired.
+     * obj = this NetworkAgentInfo
+     */
+    public static final int EVENT_NETWORK_LINGER_COMPLETE = 1001;
+
+    /**
+     * Inform ConnectivityService that the agent is half-connected.
+     * arg1 = ARG_AGENT_SUCCESS or ARG_AGENT_FAILURE
+     * obj = NetworkAgentInfo
+     * @hide
+     */
+    public static final int EVENT_AGENT_REGISTERED = 1002;
+
+    /**
+     * Inform ConnectivityService that the agent was disconnected.
+     * obj = NetworkAgentInfo
+     * @hide
+     */
+    public static final int EVENT_AGENT_DISCONNECTED = 1003;
+
+    /**
+     * Argument for EVENT_AGENT_HALF_CONNECTED indicating failure.
+     */
+    public static final int ARG_AGENT_FAILURE = 0;
+
+    /**
+     * Argument for EVENT_AGENT_HALF_CONNECTED indicating success.
+     */
+    public static final int ARG_AGENT_SUCCESS = 1;
+
+    // How long this network should linger for.
+    private int mLingerDurationMs;
+
+    // All inactivity timers for this network, sorted by expiry time. A timer is added whenever
+    // a request is moved to a network with a better score, regardless of whether the network is or
+    // was lingering or not. An inactivity timer is also added when a network connects
+    // without immediately satisfying any requests.
+    // TODO: determine if we can replace this with a smaller or unsorted data structure. (e.g.,
+    // SparseLongArray) combined with the timestamp of when the last timer is scheduled to fire.
+    private final SortedSet<InactivityTimer> mInactivityTimers = new TreeSet<>();
+
+    // For fast lookups. Indexes into mInactivityTimers by request ID.
+    private final SparseArray<InactivityTimer> mInactivityTimerForRequest = new SparseArray<>();
+
+    // Inactivity expiry timer. Armed whenever mInactivityTimers is non-empty, regardless of
+    // whether the network is inactive or not. Always set to the expiry of the mInactivityTimers
+    // that expires last. When the timer fires, all inactivity state is cleared, and if the network
+    // has no requests, it is torn down.
+    private WakeupMessage mInactivityMessage;
+
+    // Inactivity expiry. Holds the expiry time of the inactivity timer, or 0 if the timer is not
+    // armed.
+    private long mInactivityExpiryMs;
+
+    // Whether the network is inactive or not. Must be maintained separately from the above because
+    // it depends on the state of other networks and requests, which only ConnectivityService knows.
+    // (Example: we don't linger a network if it would become the best for a NetworkRequest if it
+    // validated).
+    private boolean mInactive;
+
+    // This represents the quality of the network. As opposed to NetworkScore, FullScore includes
+    // the ConnectivityService-managed bits.
+    private FullScore mScore;
+
+    // The list of NetworkRequests being satisfied by this Network.
+    private final SparseArray<NetworkRequest> mNetworkRequests = new SparseArray<>();
+
+    // How many of the satisfied requests are actual requests and not listens.
+    private int mNumRequestNetworkRequests = 0;
+
+    // How many of the satisfied requests are of type BACKGROUND_REQUEST.
+    private int mNumBackgroundNetworkRequests = 0;
+
+    // The last ConnectivityReport made available for this network. This value is only null before a
+    // report is generated. Once non-null, it will never be null again.
+    @Nullable private ConnectivityReport mConnectivityReport;
+
+    public final INetworkAgent networkAgent;
+    // Only accessed from ConnectivityService handler thread
+    private final AgentDeathMonitor mDeathMonitor = new AgentDeathMonitor();
+
+    public final int factorySerialNumber;
+
+    // Used by ConnectivityService to keep track of 464xlat.
+    public final Nat464Xlat clatd;
+
+    // Set after asynchronous creation of the NetworkMonitor.
+    private volatile NetworkMonitorManager mNetworkMonitor;
+
+    private static final String TAG = ConnectivityService.class.getSimpleName();
+    private static final boolean VDBG = false;
+    private final ConnectivityService mConnService;
+    private final Context mContext;
+    private final Handler mHandler;
+    private final QosCallbackTracker mQosCallbackTracker;
+
+    public NetworkAgentInfo(INetworkAgent na, Network net, NetworkInfo info,
+            @NonNull LinkProperties lp, @NonNull NetworkCapabilities nc,
+            @NonNull NetworkScore score, Context context,
+            Handler handler, NetworkAgentConfig config, ConnectivityService connService, INetd netd,
+            IDnsResolver dnsResolver, int factorySerialNumber, int creatorUid,
+            int lingerDurationMs, QosCallbackTracker qosCallbackTracker,
+            ConnectivityService.Dependencies deps) {
+        Objects.requireNonNull(net);
+        Objects.requireNonNull(info);
+        Objects.requireNonNull(lp);
+        Objects.requireNonNull(nc);
+        Objects.requireNonNull(context);
+        Objects.requireNonNull(config);
+        Objects.requireNonNull(qosCallbackTracker);
+        networkAgent = na;
+        network = net;
+        networkInfo = info;
+        linkProperties = lp;
+        networkCapabilities = nc;
+        networkAgentConfig = config;
+        mConnService = connService;
+        setScore(score); // uses members connService, networkCapabilities and networkAgentConfig
+        clatd = new Nat464Xlat(this, netd, dnsResolver, deps);
+        mContext = context;
+        mHandler = handler;
+        this.factorySerialNumber = factorySerialNumber;
+        this.creatorUid = creatorUid;
+        mLingerDurationMs = lingerDurationMs;
+        mQosCallbackTracker = qosCallbackTracker;
+    }
+
+    private class AgentDeathMonitor implements IBinder.DeathRecipient {
+        @Override
+        public void binderDied() {
+            notifyDisconnected();
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that it was registered, and should be unregistered if it dies.
+     *
+     * Must be called from the ConnectivityService handler thread. A NetworkAgent can only be
+     * registered once.
+     */
+    public void notifyRegistered() {
+        try {
+            networkAgent.asBinder().linkToDeath(mDeathMonitor, 0);
+            networkAgent.onRegistered(new NetworkAgentMessageHandler(mHandler));
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error registering NetworkAgent", e);
+            maybeUnlinkDeathMonitor();
+            mHandler.obtainMessage(EVENT_AGENT_REGISTERED, ARG_AGENT_FAILURE, 0, this)
+                    .sendToTarget();
+            return;
+        }
+
+        mHandler.obtainMessage(EVENT_AGENT_REGISTERED, ARG_AGENT_SUCCESS, 0, this).sendToTarget();
+    }
+
+    /**
+     * Disconnect the NetworkAgent. Must be called from the ConnectivityService handler thread.
+     */
+    public void disconnect() {
+        try {
+            networkAgent.onDisconnected();
+        } catch (RemoteException e) {
+            Log.i(TAG, "Error disconnecting NetworkAgent", e);
+            // Fall through: it's fine if the remote has died
+        }
+
+        notifyDisconnected();
+        maybeUnlinkDeathMonitor();
+    }
+
+    private void maybeUnlinkDeathMonitor() {
+        try {
+            networkAgent.asBinder().unlinkToDeath(mDeathMonitor, 0);
+        } catch (NoSuchElementException e) {
+            // Was not linked: ignore
+        }
+    }
+
+    private void notifyDisconnected() {
+        // Note this may be called multiple times if ConnectivityService disconnects while the
+        // NetworkAgent also dies. ConnectivityService ignores disconnects of already disconnected
+        // agents.
+        mHandler.obtainMessage(EVENT_AGENT_DISCONNECTED, this).sendToTarget();
+    }
+
+    /**
+     * Notify the NetworkAgent that bandwidth update was requested.
+     */
+    public void onBandwidthUpdateRequested() {
+        try {
+            networkAgent.onBandwidthUpdateRequested();
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending bandwidth update request event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that validation status has changed.
+     */
+    public void onValidationStatusChanged(int validationStatus, @Nullable String captivePortalUrl) {
+        try {
+            networkAgent.onValidationStatusChanged(validationStatus, captivePortalUrl);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending validation status change event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that the acceptUnvalidated setting should be saved.
+     */
+    public void onSaveAcceptUnvalidated(boolean acceptUnvalidated) {
+        try {
+            networkAgent.onSaveAcceptUnvalidated(acceptUnvalidated);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending accept unvalidated event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that NATT socket keepalive should be started.
+     */
+    public void onStartNattSocketKeepalive(int slot, int intervalDurationMs,
+            @NonNull NattKeepalivePacketData packetData) {
+        try {
+            networkAgent.onStartNattSocketKeepalive(slot, intervalDurationMs, packetData);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending NATT socket keepalive start event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that TCP socket keepalive should be started.
+     */
+    public void onStartTcpSocketKeepalive(int slot, int intervalDurationMs,
+            @NonNull TcpKeepalivePacketData packetData) {
+        try {
+            networkAgent.onStartTcpSocketKeepalive(slot, intervalDurationMs, packetData);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending TCP socket keepalive start event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that socket keepalive should be stopped.
+     */
+    public void onStopSocketKeepalive(int slot) {
+        try {
+            networkAgent.onStopSocketKeepalive(slot);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending TCP socket keepalive stop event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that signal strength thresholds should be updated.
+     */
+    public void onSignalStrengthThresholdsUpdated(@NonNull int[] thresholds) {
+        try {
+            networkAgent.onSignalStrengthThresholdsUpdated(thresholds);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending signal strength thresholds event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that automatic reconnect should be prevented.
+     */
+    public void onPreventAutomaticReconnect() {
+        try {
+            networkAgent.onPreventAutomaticReconnect();
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending prevent automatic reconnect event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that a NATT keepalive packet filter should be added.
+     */
+    public void onAddNattKeepalivePacketFilter(int slot,
+            @NonNull NattKeepalivePacketData packetData) {
+        try {
+            networkAgent.onAddNattKeepalivePacketFilter(slot, packetData);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending add NATT keepalive packet filter event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that a TCP keepalive packet filter should be added.
+     */
+    public void onAddTcpKeepalivePacketFilter(int slot,
+            @NonNull TcpKeepalivePacketData packetData) {
+        try {
+            networkAgent.onAddTcpKeepalivePacketFilter(slot, packetData);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending add TCP keepalive packet filter event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that a keepalive packet filter should be removed.
+     */
+    public void onRemoveKeepalivePacketFilter(int slot) {
+        try {
+            networkAgent.onRemoveKeepalivePacketFilter(slot);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending remove keepalive packet filter event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that the qos filter should be registered against the given qos
+     * callback id.
+     */
+    public void onQosFilterCallbackRegistered(final int qosCallbackId,
+            final QosFilter qosFilter) {
+        try {
+            networkAgent.onQosFilterCallbackRegistered(qosCallbackId,
+                    new QosFilterParcelable(qosFilter));
+        } catch (final RemoteException e) {
+            Log.e(TAG, "Error registering a qos callback id against a qos filter", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that the given qos callback id should be unregistered.
+     */
+    public void onQosCallbackUnregistered(final int qosCallbackId) {
+        try {
+            networkAgent.onQosCallbackUnregistered(qosCallbackId);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error unregistering a qos callback id", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that the network is successfully connected.
+     */
+    public void onNetworkCreated() {
+        try {
+            networkAgent.onNetworkCreated();
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending network created event", e);
+        }
+    }
+
+    /**
+     * Notify the NetworkAgent that the native network has been destroyed.
+     */
+    public void onNetworkDestroyed() {
+        try {
+            networkAgent.onNetworkDestroyed();
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error sending network destroyed event", e);
+        }
+    }
+
+    // TODO: consider moving out of NetworkAgentInfo into its own class
+    private class NetworkAgentMessageHandler extends INetworkAgentRegistry.Stub {
+        private final Handler mHandler;
+
+        private NetworkAgentMessageHandler(Handler handler) {
+            mHandler = handler;
+        }
+
+        @Override
+        public void sendNetworkCapabilities(@NonNull NetworkCapabilities nc) {
+            Objects.requireNonNull(nc);
+            mHandler.obtainMessage(NetworkAgent.EVENT_NETWORK_CAPABILITIES_CHANGED,
+                    new Pair<>(NetworkAgentInfo.this, nc)).sendToTarget();
+        }
+
+        @Override
+        public void sendLinkProperties(@NonNull LinkProperties lp) {
+            Objects.requireNonNull(lp);
+            mHandler.obtainMessage(NetworkAgent.EVENT_NETWORK_PROPERTIES_CHANGED,
+                    new Pair<>(NetworkAgentInfo.this, lp)).sendToTarget();
+        }
+
+        @Override
+        public void sendNetworkInfo(@NonNull NetworkInfo info) {
+            Objects.requireNonNull(info);
+            mHandler.obtainMessage(NetworkAgent.EVENT_NETWORK_INFO_CHANGED,
+                    new Pair<>(NetworkAgentInfo.this, info)).sendToTarget();
+        }
+
+        @Override
+        public void sendScore(@NonNull final NetworkScore score) {
+            mHandler.obtainMessage(NetworkAgent.EVENT_NETWORK_SCORE_CHANGED,
+                    new Pair<>(NetworkAgentInfo.this, score)).sendToTarget();
+        }
+
+        @Override
+        public void sendExplicitlySelected(boolean explicitlySelected, boolean acceptPartial) {
+            mHandler.obtainMessage(NetworkAgent.EVENT_SET_EXPLICITLY_SELECTED,
+                    explicitlySelected ? 1 : 0, acceptPartial ? 1 : 0,
+                    new Pair<>(NetworkAgentInfo.this, null)).sendToTarget();
+        }
+
+        @Override
+        public void sendSocketKeepaliveEvent(int slot, int reason) {
+            mHandler.obtainMessage(NetworkAgent.EVENT_SOCKET_KEEPALIVE,
+                    slot, reason, new Pair<>(NetworkAgentInfo.this, null)).sendToTarget();
+        }
+
+        @Override
+        public void sendUnderlyingNetworks(@Nullable List<Network> networks) {
+            mHandler.obtainMessage(NetworkAgent.EVENT_UNDERLYING_NETWORKS_CHANGED,
+                    new Pair<>(NetworkAgentInfo.this, networks)).sendToTarget();
+        }
+
+        @Override
+        public void sendEpsQosSessionAvailable(final int qosCallbackId, final QosSession session,
+                final EpsBearerQosSessionAttributes attributes) {
+            mQosCallbackTracker.sendEventEpsQosSessionAvailable(qosCallbackId, session, attributes);
+        }
+
+        @Override
+        public void sendNrQosSessionAvailable(final int qosCallbackId, final QosSession session,
+                final NrQosSessionAttributes attributes) {
+            mQosCallbackTracker.sendEventNrQosSessionAvailable(qosCallbackId, session, attributes);
+        }
+
+        @Override
+        public void sendQosSessionLost(final int qosCallbackId, final QosSession session) {
+            mQosCallbackTracker.sendEventQosSessionLost(qosCallbackId, session);
+        }
+
+        @Override
+        public void sendQosCallbackError(final int qosCallbackId,
+                @QosCallbackException.ExceptionType final int exceptionType) {
+            mQosCallbackTracker.sendEventQosCallbackError(qosCallbackId, exceptionType);
+        }
+
+        @Override
+        public void sendTeardownDelayMs(int teardownDelayMs) {
+            mHandler.obtainMessage(NetworkAgent.EVENT_TEARDOWN_DELAY_CHANGED,
+                    teardownDelayMs, 0, new Pair<>(NetworkAgentInfo.this, null)).sendToTarget();
+        }
+
+        @Override
+        public void sendLingerDuration(final int durationMs) {
+            mHandler.obtainMessage(NetworkAgent.EVENT_LINGER_DURATION_CHANGED,
+                    new Pair<>(NetworkAgentInfo.this, durationMs)).sendToTarget();
+        }
+    }
+
+    /**
+     * Inform NetworkAgentInfo that a new NetworkMonitor was created.
+     */
+    public void onNetworkMonitorCreated(INetworkMonitor networkMonitor) {
+        mNetworkMonitor = new NetworkMonitorManager(networkMonitor);
+    }
+
+    /**
+     * Set the NetworkCapabilities on this NetworkAgentInfo. Also attempts to notify NetworkMonitor
+     * of the new capabilities, if NetworkMonitor has been created.
+     *
+     * <p>If {@link NetworkMonitor#notifyNetworkCapabilitiesChanged(NetworkCapabilities)} fails,
+     * the exception is logged but not reported to callers.
+     *
+     * @return the old capabilities of this network.
+     */
+    @NonNull public synchronized NetworkCapabilities getAndSetNetworkCapabilities(
+            @NonNull final NetworkCapabilities nc) {
+        final NetworkCapabilities oldNc = networkCapabilities;
+        networkCapabilities = nc;
+        mScore = mScore.mixInScore(networkCapabilities, networkAgentConfig, everValidatedForYield(),
+                yieldToBadWiFi());
+        final NetworkMonitorManager nm = mNetworkMonitor;
+        if (nm != null) {
+            nm.notifyNetworkCapabilitiesChanged(nc);
+        }
+        return oldNc;
+    }
+
+    private boolean yieldToBadWiFi() {
+        // Only cellular networks yield to bad wifi
+        return networkCapabilities.hasTransport(TRANSPORT_CELLULAR) && !mConnService.avoidBadWifi();
+    }
+
+    public ConnectivityService connService() {
+        return mConnService;
+    }
+
+    public NetworkAgentConfig netAgentConfig() {
+        return networkAgentConfig;
+    }
+
+    public Handler handler() {
+        return mHandler;
+    }
+
+    public Network network() {
+        return network;
+    }
+
+    /**
+     * Get the NetworkMonitorManager in this NetworkAgentInfo.
+     *
+     * <p>This will be null before {@link #onNetworkMonitorCreated(INetworkMonitor)} is called.
+     */
+    public NetworkMonitorManager networkMonitor() {
+        return mNetworkMonitor;
+    }
+
+    // Functions for manipulating the requests satisfied by this network.
+    //
+    // These functions must only called on ConnectivityService's main thread.
+
+    private static final boolean ADD = true;
+    private static final boolean REMOVE = false;
+
+    private void updateRequestCounts(boolean add, NetworkRequest request) {
+        int delta = add ? +1 : -1;
+        switch (request.type) {
+            case REQUEST:
+                mNumRequestNetworkRequests += delta;
+                break;
+
+            case BACKGROUND_REQUEST:
+                mNumRequestNetworkRequests += delta;
+                mNumBackgroundNetworkRequests += delta;
+                break;
+
+            case LISTEN:
+            case LISTEN_FOR_BEST:
+            case TRACK_DEFAULT:
+            case TRACK_SYSTEM_DEFAULT:
+                break;
+
+            case NONE:
+            default:
+                Log.wtf(TAG, "Unhandled request type " + request.type);
+                break;
+        }
+    }
+
+    /**
+     * Add {@code networkRequest} to this network as it's satisfied by this network.
+     * @return true if {@code networkRequest} was added or false if {@code networkRequest} was
+     *         already present.
+     */
+    public boolean addRequest(NetworkRequest networkRequest) {
+        NetworkRequest existing = mNetworkRequests.get(networkRequest.requestId);
+        if (existing == networkRequest) return false;
+        if (existing != null) {
+            // Should only happen if the requestId wraps. If that happens lots of other things will
+            // be broken as well.
+            Log.wtf(TAG, String.format("Duplicate requestId for %s and %s on %s",
+                    networkRequest, existing, toShortString()));
+            updateRequestCounts(REMOVE, existing);
+        }
+        mNetworkRequests.put(networkRequest.requestId, networkRequest);
+        updateRequestCounts(ADD, networkRequest);
+        return true;
+    }
+
+    /**
+     * Remove the specified request from this network.
+     */
+    public void removeRequest(int requestId) {
+        NetworkRequest existing = mNetworkRequests.get(requestId);
+        if (existing == null) return;
+        updateRequestCounts(REMOVE, existing);
+        mNetworkRequests.remove(requestId);
+        if (existing.isRequest()) {
+            unlingerRequest(existing.requestId);
+        }
+    }
+
+    /**
+     * Returns whether this network is currently satisfying the request with the specified ID.
+     */
+    public boolean isSatisfyingRequest(int id) {
+        return mNetworkRequests.get(id) != null;
+    }
+
+    /**
+     * Returns the request at the specified position in the list of requests satisfied by this
+     * network.
+     */
+    public NetworkRequest requestAt(int index) {
+        return mNetworkRequests.valueAt(index);
+    }
+
+    /**
+     * Returns the number of requests currently satisfied by this network for which
+     * {@link android.net.NetworkRequest#isRequest} returns {@code true}.
+     */
+    public int numRequestNetworkRequests() {
+        return mNumRequestNetworkRequests;
+    }
+
+    /**
+     * Returns the number of requests currently satisfied by this network of type
+     * {@link android.net.NetworkRequest.Type.BACKGROUND_REQUEST}.
+     */
+    public int numBackgroundNetworkRequests() {
+        return mNumBackgroundNetworkRequests;
+    }
+
+    /**
+     * Returns the number of foreground requests currently satisfied by this network.
+     */
+    public int numForegroundNetworkRequests() {
+        return mNumRequestNetworkRequests - mNumBackgroundNetworkRequests;
+    }
+
+    /**
+     * Returns the number of requests of any type currently satisfied by this network.
+     */
+    public int numNetworkRequests() {
+        return mNetworkRequests.size();
+    }
+
+    /**
+     * Returns whether the network is a background network. A network is a background network if it
+     * does not have the NET_CAPABILITY_FOREGROUND capability, which implies it is satisfying no
+     * foreground request, is not lingering (i.e. kept for a while after being outscored), and is
+     * not a speculative network (i.e. kept pending validation when validation would have it
+     * outscore another foreground network). That implies it is being kept up by some background
+     * request (otherwise it would be torn down), maybe the mobile always-on request.
+     */
+    public boolean isBackgroundNetwork() {
+        return !isVPN() && numForegroundNetworkRequests() == 0 && mNumBackgroundNetworkRequests > 0
+                && !isLingering();
+    }
+
+    // Does this network satisfy request?
+    public boolean satisfies(NetworkRequest request) {
+        return created &&
+                request.networkCapabilities.satisfiedByNetworkCapabilities(networkCapabilities);
+    }
+
+    public boolean satisfiesImmutableCapabilitiesOf(NetworkRequest request) {
+        return created &&
+                request.networkCapabilities.satisfiedByImmutableNetworkCapabilities(
+                        networkCapabilities);
+    }
+
+    /** Whether this network is a VPN. */
+    public boolean isVPN() {
+        return networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_VPN);
+    }
+
+    /** Whether this network might have underlying networks. Currently only true for VPNs. */
+    public boolean supportsUnderlyingNetworks() {
+        return isVPN();
+    }
+
+    // Caller must not mutate. This method is called frequently and making a defensive copy
+    // would be too expensive. This is used by NetworkRanker.Scoreable, so it can be compared
+    // against other scoreables.
+    @Override public NetworkCapabilities getCapsNoCopy() {
+        return networkCapabilities;
+    }
+
+    // NetworkRanker.Scoreable
+    @Override public FullScore getScore() {
+        return mScore;
+    }
+
+    // Get the current score for this Network.  This may be modified from what the
+    // NetworkAgent sent, as it has modifiers applied to it.
+    public int getCurrentScore() {
+        return mScore.getLegacyInt();
+    }
+
+    // Get the current score for this Network as if it was validated.  This may be modified from
+    // what the NetworkAgent sent, as it has modifiers applied to it.
+    public int getCurrentScoreAsValidated() {
+        return mScore.getLegacyIntAsValidated();
+    }
+
+    /**
+     * Mix-in the ConnectivityService-managed bits in the score.
+     */
+    public void setScore(final NetworkScore score) {
+        mScore = FullScore.fromNetworkScore(score, networkCapabilities, networkAgentConfig,
+                everValidatedForYield(), yieldToBadWiFi());
+    }
+
+    /**
+     * Update the ConnectivityService-managed bits in the score.
+     *
+     * Call this after updating the network agent config.
+     */
+    public void updateScoreForNetworkAgentUpdate() {
+        mScore = mScore.mixInScore(networkCapabilities, networkAgentConfig,
+                everValidatedForYield(), yieldToBadWiFi());
+    }
+
+    private boolean everValidatedForYield() {
+        return everValidated && !avoidUnvalidated;
+    }
+
+    /**
+     * Returns a Scoreable identical to this NAI, but validated.
+     *
+     * This is useful to probe what scoring would be if this network validated, to know
+     * whether to provisionally keep a network that may or may not validate.
+     *
+     * @return a Scoreable identical to this NAI, but validated.
+     */
+    public NetworkRanker.Scoreable getValidatedScoreable() {
+        return new NetworkRanker.Scoreable() {
+            @Override public FullScore getScore() {
+                return mScore.asValidated();
+            }
+
+            @Override public NetworkCapabilities getCapsNoCopy() {
+                return networkCapabilities;
+            }
+        };
+    }
+
+    /**
+     * Return a {@link NetworkStateSnapshot} for this network.
+     */
+    @NonNull
+    public NetworkStateSnapshot getNetworkStateSnapshot() {
+        synchronized (this) {
+            // Network objects are outwardly immutable so there is no point in duplicating.
+            // Duplicating also precludes sharing socket factories and connection pools.
+            final String subscriberId = (networkAgentConfig != null)
+                    ? networkAgentConfig.subscriberId : null;
+            return new NetworkStateSnapshot(network, new NetworkCapabilities(networkCapabilities),
+                    new LinkProperties(linkProperties), subscriberId, networkInfo.getType());
+        }
+    }
+
+    /**
+     * Sets the specified requestId to linger on this network for the specified time. Called by
+     * ConnectivityService when any request is moved to another network with a higher score, or
+     * when a network is newly created.
+     *
+     * @param requestId The requestId of the request that no longer need to be served by this
+     *                  network. Or {@link NetworkRequest.REQUEST_ID_NONE} if this is the
+     *                  {@code InactivityTimer} for a newly created network.
+     */
+    // TODO: Consider creating a dedicated function for nascent network, e.g. start/stopNascent.
+    public void lingerRequest(int requestId, long now, long duration) {
+        if (mInactivityTimerForRequest.get(requestId) != null) {
+            // Cannot happen. Once a request is lingering on a particular network, we cannot
+            // re-linger it unless that network becomes the best for that request again, in which
+            // case we should have unlingered it.
+            Log.wtf(TAG, toShortString() + ": request " + requestId + " already lingered");
+        }
+        final long expiryMs = now + duration;
+        InactivityTimer timer = new InactivityTimer(requestId, expiryMs);
+        if (VDBG) Log.d(TAG, "Adding InactivityTimer " + timer + " to " + toShortString());
+        mInactivityTimers.add(timer);
+        mInactivityTimerForRequest.put(requestId, timer);
+    }
+
+    /**
+     * Sets the specified requestId to linger on this network for the timeout set when
+     * initializing or modified by {@link #setLingerDuration(int)}. Called by
+     * ConnectivityService when any request is moved to another network with a higher score.
+     *
+     * @param requestId The requestId of the request that no longer need to be served by this
+     *                  network.
+     * @param now current system timestamp obtained by {@code SystemClock.elapsedRealtime}.
+     */
+    public void lingerRequest(int requestId, long now) {
+        lingerRequest(requestId, now, mLingerDurationMs);
+    }
+
+    /**
+     * Cancel lingering. Called by ConnectivityService when a request is added to this network.
+     * Returns true if the given requestId was lingering on this network, false otherwise.
+     */
+    public boolean unlingerRequest(int requestId) {
+        InactivityTimer timer = mInactivityTimerForRequest.get(requestId);
+        if (timer != null) {
+            if (VDBG) {
+                Log.d(TAG, "Removing InactivityTimer " + timer + " from " + toShortString());
+            }
+            mInactivityTimers.remove(timer);
+            mInactivityTimerForRequest.remove(requestId);
+            return true;
+        }
+        return false;
+    }
+
+    public long getInactivityExpiry() {
+        return mInactivityExpiryMs;
+    }
+
+    public void updateInactivityTimer() {
+        long newExpiry = mInactivityTimers.isEmpty() ? 0 : mInactivityTimers.last().expiryMs;
+        if (newExpiry == mInactivityExpiryMs) return;
+
+        // Even if we're going to reschedule the timer, cancel it first. This is because the
+        // semantics of WakeupMessage guarantee that if cancel is called then the alarm will
+        // never call its callback (handleLingerComplete), even if it has already fired.
+        // WakeupMessage makes no such guarantees about rescheduling a message, so if mLingerMessage
+        // has already been dispatched, rescheduling to some time in the future won't stop it
+        // from calling its callback immediately.
+        if (mInactivityMessage != null) {
+            mInactivityMessage.cancel();
+            mInactivityMessage = null;
+        }
+
+        if (newExpiry > 0) {
+            // If the newExpiry timestamp is in the past, the wakeup message will fire immediately.
+            mInactivityMessage = new WakeupMessage(
+                    mContext, mHandler,
+                    "NETWORK_LINGER_COMPLETE." + network.getNetId() /* cmdName */,
+                    EVENT_NETWORK_LINGER_COMPLETE /* cmd */,
+                    0 /* arg1 (unused) */, 0 /* arg2 (unused) */,
+                    this /* obj (NetworkAgentInfo) */);
+            mInactivityMessage.schedule(newExpiry);
+        }
+
+        mInactivityExpiryMs = newExpiry;
+    }
+
+    public void setInactive() {
+        mInactive = true;
+    }
+
+    public void unsetInactive() {
+        mInactive = false;
+    }
+
+    public boolean isInactive() {
+        return mInactive;
+    }
+
+    public boolean isLingering() {
+        return mInactive && !isNascent();
+    }
+
+    /**
+     * Set the linger duration for this NAI.
+     * @param durationMs The new linger duration, in milliseconds.
+     */
+    public void setLingerDuration(final int durationMs) {
+        final long diff = durationMs - mLingerDurationMs;
+        final ArrayList<InactivityTimer> newTimers = new ArrayList<>();
+        for (final InactivityTimer timer : mInactivityTimers) {
+            if (timer.requestId == NetworkRequest.REQUEST_ID_NONE) {
+                // Don't touch nascent timer, re-add as is.
+                newTimers.add(timer);
+            } else {
+                newTimers.add(new InactivityTimer(timer.requestId, timer.expiryMs + diff));
+            }
+        }
+        mInactivityTimers.clear();
+        mInactivityTimers.addAll(newTimers);
+        updateInactivityTimer();
+        mLingerDurationMs = durationMs;
+    }
+
+    /**
+     * Return whether the network satisfies no request, but is still being kept up
+     * because it has just connected less than
+     * {@code ConnectivityService#DEFAULT_NASCENT_DELAY_MS}ms ago and is thus still considered
+     * nascent. Note that nascent mechanism uses inactivity timer which isn't
+     * associated with a request. Thus, use {@link NetworkRequest#REQUEST_ID_NONE} to identify it.
+     *
+     */
+    public boolean isNascent() {
+        return mInactive && mInactivityTimers.size() == 1
+                && mInactivityTimers.first().requestId == NetworkRequest.REQUEST_ID_NONE;
+    }
+
+    public void clearInactivityState() {
+        if (mInactivityMessage != null) {
+            mInactivityMessage.cancel();
+            mInactivityMessage = null;
+        }
+        mInactivityTimers.clear();
+        mInactivityTimerForRequest.clear();
+        // Sets mInactivityExpiryMs, cancels and nulls out mInactivityMessage.
+        updateInactivityTimer();
+        mInactive = false;
+    }
+
+    public void dumpInactivityTimers(PrintWriter pw) {
+        for (InactivityTimer timer : mInactivityTimers) {
+            pw.println(timer);
+        }
+    }
+
+    /**
+     * Sets the most recent ConnectivityReport for this network.
+     *
+     * <p>This should only be called from the ConnectivityService thread.
+     *
+     * @hide
+     */
+    public void setConnectivityReport(@NonNull ConnectivityReport connectivityReport) {
+        mConnectivityReport = connectivityReport;
+    }
+
+    /**
+     * Returns the most recent ConnectivityReport for this network, or null if none have been
+     * reported yet.
+     *
+     * <p>This should only be called from the ConnectivityService thread.
+     *
+     * @hide
+     */
+    @Nullable
+    public ConnectivityReport getConnectivityReport() {
+        return mConnectivityReport;
+    }
+
+    // TODO: Print shorter members first and only print the boolean variable which value is true
+    // to improve readability.
+    public String toString() {
+        return "NetworkAgentInfo{"
+                + "network{" + network + "}  handle{" + network.getNetworkHandle() + "}  ni{"
+                + networkInfo.toShortString() + "} "
+                + mScore + " "
+                + (isNascent() ? " nascent" : (isLingering() ? " lingering" : ""))
+                + (everValidated ? " everValidated" : "")
+                + (lastValidated ? " lastValidated" : "")
+                + (partialConnectivity ? " partialConnectivity" : "")
+                + (everCaptivePortalDetected ? " everCaptivePortal" : "")
+                + (lastCaptivePortalDetected ? " isCaptivePortal" : "")
+                + (networkAgentConfig.explicitlySelected ? " explicitlySelected" : "")
+                + (networkAgentConfig.acceptUnvalidated ? " acceptUnvalidated" : "")
+                + (networkAgentConfig.acceptPartialConnectivity ? " acceptPartialConnectivity" : "")
+                + (clatd.isStarted() ? " clat{" + clatd + "} " : "")
+                + (declaredUnderlyingNetworks != null
+                        ? " underlying{" + Arrays.toString(declaredUnderlyingNetworks) + "}" : "")
+                + "  lp{" + linkProperties + "}"
+                + "  nc{" + networkCapabilities + "}"
+                + "}";
+    }
+
+    /**
+     * Show a short string representing a Network.
+     *
+     * This is often not enough for debugging purposes for anything complex, but the full form
+     * is very long and hard to read, so this is useful when there isn't a lot of ambiguity.
+     * This represents the network with something like "[100 WIFI|VPN]" or "[108 MOBILE]".
+     */
+    public String toShortString() {
+        return "[" + network.getNetId() + " "
+                + transportNamesOf(networkCapabilities.getTransportTypes()) + "]";
+    }
+
+    // Enables sorting in descending order of score.
+    @Override
+    public int compareTo(NetworkAgentInfo other) {
+        return other.getCurrentScore() - getCurrentScore();
+    }
+
+    /**
+     * Null-guarding version of NetworkAgentInfo#toShortString()
+     */
+    @NonNull
+    public static String toShortString(@Nullable final NetworkAgentInfo nai) {
+        return null != nai ? nai.toShortString() : "[null]";
+    }
+}
diff --git a/service/src/com/android/server/connectivity/NetworkDiagnostics.java b/service/src/com/android/server/connectivity/NetworkDiagnostics.java
new file mode 100644
index 0000000..2e51be3
--- /dev/null
+++ b/service/src/com/android/server/connectivity/NetworkDiagnostics.java
@@ -0,0 +1,757 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.system.OsConstants.*;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.net.InetAddresses;
+import android.net.LinkAddress;
+import android.net.LinkProperties;
+import android.net.Network;
+import android.net.RouteInfo;
+import android.net.TrafficStats;
+import android.net.shared.PrivateDnsConfig;
+import android.net.util.NetworkConstants;
+import android.os.SystemClock;
+import android.system.ErrnoException;
+import android.system.Os;
+import android.system.StructTimeval;
+import android.text.TextUtils;
+import android.util.Pair;
+
+import com.android.internal.util.IndentingPrintWriter;
+import com.android.net.module.util.NetworkStackConstants;
+
+import libcore.io.IoUtils;
+
+import java.io.Closeable;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.FileDescriptor;
+import java.io.IOException;
+import java.io.InterruptedIOException;
+import java.net.Inet4Address;
+import java.net.Inet6Address;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.NetworkInterface;
+import java.net.SocketAddress;
+import java.net.SocketException;
+import java.net.UnknownHostException;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import javax.net.ssl.SNIHostName;
+import javax.net.ssl.SNIServerName;
+import javax.net.ssl.SSLParameters;
+import javax.net.ssl.SSLSocket;
+import javax.net.ssl.SSLSocketFactory;
+
+/**
+ * NetworkDiagnostics
+ *
+ * A simple class to diagnose network connectivity fundamentals.  Current
+ * checks performed are:
+ *     - ICMPv4/v6 echo requests for all routers
+ *     - ICMPv4/v6 echo requests for all DNS servers
+ *     - DNS UDP queries to all DNS servers
+ *
+ * Currently unimplemented checks include:
+ *     - report ARP/ND data about on-link neighbors
+ *     - DNS TCP queries to all DNS servers
+ *     - HTTP DIRECT and PROXY checks
+ *     - port 443 blocking/TLS intercept checks
+ *     - QUIC reachability checks
+ *     - MTU checks
+ *
+ * The supplied timeout bounds the entire diagnostic process.  Each specific
+ * check class must implement this upper bound on measurements in whichever
+ * manner is most appropriate and effective.
+ *
+ * @hide
+ */
+public class NetworkDiagnostics {
+    private static final String TAG = "NetworkDiagnostics";
+
+    private static final InetAddress TEST_DNS4 = InetAddresses.parseNumericAddress("8.8.8.8");
+    private static final InetAddress TEST_DNS6 = InetAddresses.parseNumericAddress(
+            "2001:4860:4860::8888");
+
+    // For brevity elsewhere.
+    private static final long now() {
+        return SystemClock.elapsedRealtime();
+    }
+
+    // Values from RFC 1035 section 4.1.1, names from <arpa/nameser.h>.
+    // Should be a member of DnsUdpCheck, but "compiler says no".
+    public static enum DnsResponseCode { NOERROR, FORMERR, SERVFAIL, NXDOMAIN, NOTIMP, REFUSED };
+
+    private final Network mNetwork;
+    private final LinkProperties mLinkProperties;
+    private final PrivateDnsConfig mPrivateDnsCfg;
+    private final Integer mInterfaceIndex;
+
+    private final long mTimeoutMs;
+    private final long mStartTime;
+    private final long mDeadlineTime;
+
+    // A counter, initialized to the total number of measurements,
+    // so callers can wait for completion.
+    private final CountDownLatch mCountDownLatch;
+
+    public class Measurement {
+        private static final String SUCCEEDED = "SUCCEEDED";
+        private static final String FAILED = "FAILED";
+
+        private boolean succeeded;
+
+        // Package private.  TODO: investigate better encapsulation.
+        String description = "";
+        long startTime;
+        long finishTime;
+        String result = "";
+        Thread thread;
+
+        public boolean checkSucceeded() { return succeeded; }
+
+        void recordSuccess(String msg) {
+            maybeFixupTimes();
+            succeeded = true;
+            result = SUCCEEDED + ": " + msg;
+            if (mCountDownLatch != null) {
+                mCountDownLatch.countDown();
+            }
+        }
+
+        void recordFailure(String msg) {
+            maybeFixupTimes();
+            succeeded = false;
+            result = FAILED + ": " + msg;
+            if (mCountDownLatch != null) {
+                mCountDownLatch.countDown();
+            }
+        }
+
+        private void maybeFixupTimes() {
+            // Allows the caller to just set success/failure and not worry
+            // about also setting the correct finishing time.
+            if (finishTime == 0) { finishTime = now(); }
+
+            // In cases where, for example, a failure has occurred before the
+            // measurement even began, fixup the start time to reflect as much.
+            if (startTime == 0) { startTime = finishTime; }
+        }
+
+        @Override
+        public String toString() {
+            return description + ": " + result + " (" + (finishTime - startTime) + "ms)";
+        }
+    }
+
+    private final Map<InetAddress, Measurement> mIcmpChecks = new HashMap<>();
+    private final Map<Pair<InetAddress, InetAddress>, Measurement> mExplicitSourceIcmpChecks =
+            new HashMap<>();
+    private final Map<InetAddress, Measurement> mDnsUdpChecks = new HashMap<>();
+    private final Map<InetAddress, Measurement> mDnsTlsChecks = new HashMap<>();
+    private final String mDescription;
+
+
+    public NetworkDiagnostics(Network network, LinkProperties lp,
+            @NonNull PrivateDnsConfig privateDnsCfg, long timeoutMs) {
+        mNetwork = network;
+        mLinkProperties = lp;
+        mPrivateDnsCfg = privateDnsCfg;
+        mInterfaceIndex = getInterfaceIndex(mLinkProperties.getInterfaceName());
+        mTimeoutMs = timeoutMs;
+        mStartTime = now();
+        mDeadlineTime = mStartTime + mTimeoutMs;
+
+        // Hardcode measurements to TEST_DNS4 and TEST_DNS6 in order to test off-link connectivity.
+        // We are free to modify mLinkProperties with impunity because ConnectivityService passes us
+        // a copy and not the original object. It's easier to do it this way because we don't need
+        // to check whether the LinkProperties already contains these DNS servers because
+        // LinkProperties#addDnsServer checks for duplicates.
+        if (mLinkProperties.isReachable(TEST_DNS4)) {
+            mLinkProperties.addDnsServer(TEST_DNS4);
+        }
+        // TODO: we could use mLinkProperties.isReachable(TEST_DNS6) here, because we won't set any
+        // DNS servers for which isReachable() is false, but since this is diagnostic code, be extra
+        // careful.
+        if (mLinkProperties.hasGlobalIpv6Address() || mLinkProperties.hasIpv6DefaultRoute()) {
+            mLinkProperties.addDnsServer(TEST_DNS6);
+        }
+
+        for (RouteInfo route : mLinkProperties.getRoutes()) {
+            if (route.hasGateway()) {
+                InetAddress gateway = route.getGateway();
+                prepareIcmpMeasurement(gateway);
+                if (route.isIPv6Default()) {
+                    prepareExplicitSourceIcmpMeasurements(gateway);
+                }
+            }
+        }
+        for (InetAddress nameserver : mLinkProperties.getDnsServers()) {
+            prepareIcmpMeasurement(nameserver);
+            prepareDnsMeasurement(nameserver);
+
+            // Unlike the DnsResolver which doesn't do certificate validation in opportunistic mode,
+            // DoT probes to the DNS servers will fail if certificate validation fails.
+            prepareDnsTlsMeasurement(null /* hostname */, nameserver);
+        }
+
+        for (InetAddress tlsNameserver : mPrivateDnsCfg.ips) {
+            // Reachability check is necessary since when resolving the strict mode hostname,
+            // NetworkMonitor always queries for both A and AAAA records, even if the network
+            // is IPv4-only or IPv6-only.
+            if (mLinkProperties.isReachable(tlsNameserver)) {
+                // If there are IPs, there must have been a name that resolved to them.
+                prepareDnsTlsMeasurement(mPrivateDnsCfg.hostname, tlsNameserver);
+            }
+        }
+
+        mCountDownLatch = new CountDownLatch(totalMeasurementCount());
+
+        startMeasurements();
+
+        mDescription = "ifaces{" + TextUtils.join(",", mLinkProperties.getAllInterfaceNames()) + "}"
+                + " index{" + mInterfaceIndex + "}"
+                + " network{" + mNetwork + "}"
+                + " nethandle{" + mNetwork.getNetworkHandle() + "}";
+    }
+
+    private static Integer getInterfaceIndex(String ifname) {
+        try {
+            NetworkInterface ni = NetworkInterface.getByName(ifname);
+            return ni.getIndex();
+        } catch (NullPointerException | SocketException e) {
+            return null;
+        }
+    }
+
+    private static String socketAddressToString(@NonNull SocketAddress sockAddr) {
+        // The default toString() implementation is not the prettiest.
+        InetSocketAddress inetSockAddr = (InetSocketAddress) sockAddr;
+        InetAddress localAddr = inetSockAddr.getAddress();
+        return String.format(
+                (localAddr instanceof Inet6Address ? "[%s]:%d" : "%s:%d"),
+                localAddr.getHostAddress(), inetSockAddr.getPort());
+    }
+
+    private void prepareIcmpMeasurement(InetAddress target) {
+        if (!mIcmpChecks.containsKey(target)) {
+            Measurement measurement = new Measurement();
+            measurement.thread = new Thread(new IcmpCheck(target, measurement));
+            mIcmpChecks.put(target, measurement);
+        }
+    }
+
+    private void prepareExplicitSourceIcmpMeasurements(InetAddress target) {
+        for (LinkAddress l : mLinkProperties.getLinkAddresses()) {
+            InetAddress source = l.getAddress();
+            if (source instanceof Inet6Address && l.isGlobalPreferred()) {
+                Pair<InetAddress, InetAddress> srcTarget = new Pair<>(source, target);
+                if (!mExplicitSourceIcmpChecks.containsKey(srcTarget)) {
+                    Measurement measurement = new Measurement();
+                    measurement.thread = new Thread(new IcmpCheck(source, target, measurement));
+                    mExplicitSourceIcmpChecks.put(srcTarget, measurement);
+                }
+            }
+        }
+    }
+
+    private void prepareDnsMeasurement(InetAddress target) {
+        if (!mDnsUdpChecks.containsKey(target)) {
+            Measurement measurement = new Measurement();
+            measurement.thread = new Thread(new DnsUdpCheck(target, measurement));
+            mDnsUdpChecks.put(target, measurement);
+        }
+    }
+
+    private void prepareDnsTlsMeasurement(@Nullable String hostname, @NonNull InetAddress target) {
+        // This might overwrite an existing entry in mDnsTlsChecks, because |target| can be an IP
+        // address configured by the network as well as an IP address learned by resolving the
+        // strict mode DNS hostname. If the entry is overwritten, the overwritten measurement
+        // thread will not execute.
+        Measurement measurement = new Measurement();
+        measurement.thread = new Thread(new DnsTlsCheck(hostname, target, measurement));
+        mDnsTlsChecks.put(target, measurement);
+    }
+
+    private int totalMeasurementCount() {
+        return mIcmpChecks.size() + mExplicitSourceIcmpChecks.size() + mDnsUdpChecks.size()
+                + mDnsTlsChecks.size();
+    }
+
+    private void startMeasurements() {
+        for (Measurement measurement : mIcmpChecks.values()) {
+            measurement.thread.start();
+        }
+        for (Measurement measurement : mExplicitSourceIcmpChecks.values()) {
+            measurement.thread.start();
+        }
+        for (Measurement measurement : mDnsUdpChecks.values()) {
+            measurement.thread.start();
+        }
+        for (Measurement measurement : mDnsTlsChecks.values()) {
+            measurement.thread.start();
+        }
+    }
+
+    public void waitForMeasurements() {
+        try {
+            mCountDownLatch.await(mDeadlineTime - now(), TimeUnit.MILLISECONDS);
+        } catch (InterruptedException ignored) {}
+    }
+
+    public List<Measurement> getMeasurements() {
+        // TODO: Consider moving waitForMeasurements() in here to minimize the
+        // chance of caller errors.
+
+        ArrayList<Measurement> measurements = new ArrayList(totalMeasurementCount());
+
+        // Sort measurements IPv4 first.
+        for (Map.Entry<InetAddress, Measurement> entry : mIcmpChecks.entrySet()) {
+            if (entry.getKey() instanceof Inet4Address) {
+                measurements.add(entry.getValue());
+            }
+        }
+        for (Map.Entry<Pair<InetAddress, InetAddress>, Measurement> entry :
+                mExplicitSourceIcmpChecks.entrySet()) {
+            if (entry.getKey().first instanceof Inet4Address) {
+                measurements.add(entry.getValue());
+            }
+        }
+        for (Map.Entry<InetAddress, Measurement> entry : mDnsUdpChecks.entrySet()) {
+            if (entry.getKey() instanceof Inet4Address) {
+                measurements.add(entry.getValue());
+            }
+        }
+        for (Map.Entry<InetAddress, Measurement> entry : mDnsTlsChecks.entrySet()) {
+            if (entry.getKey() instanceof Inet4Address) {
+                measurements.add(entry.getValue());
+            }
+        }
+
+        // IPv6 measurements second.
+        for (Map.Entry<InetAddress, Measurement> entry : mIcmpChecks.entrySet()) {
+            if (entry.getKey() instanceof Inet6Address) {
+                measurements.add(entry.getValue());
+            }
+        }
+        for (Map.Entry<Pair<InetAddress, InetAddress>, Measurement> entry :
+                mExplicitSourceIcmpChecks.entrySet()) {
+            if (entry.getKey().first instanceof Inet6Address) {
+                measurements.add(entry.getValue());
+            }
+        }
+        for (Map.Entry<InetAddress, Measurement> entry : mDnsUdpChecks.entrySet()) {
+            if (entry.getKey() instanceof Inet6Address) {
+                measurements.add(entry.getValue());
+            }
+        }
+        for (Map.Entry<InetAddress, Measurement> entry : mDnsTlsChecks.entrySet()) {
+            if (entry.getKey() instanceof Inet6Address) {
+                measurements.add(entry.getValue());
+            }
+        }
+
+        return measurements;
+    }
+
+    public void dump(IndentingPrintWriter pw) {
+        pw.println(TAG + ":" + mDescription);
+        final long unfinished = mCountDownLatch.getCount();
+        if (unfinished > 0) {
+            // This can't happen unless a caller forgets to call waitForMeasurements()
+            // or a measurement isn't implemented to correctly honor the timeout.
+            pw.println("WARNING: countdown wait incomplete: "
+                    + unfinished + " unfinished measurements");
+        }
+
+        pw.increaseIndent();
+
+        String prefix;
+        for (Measurement m : getMeasurements()) {
+            prefix = m.checkSucceeded() ? "." : "F";
+            pw.println(prefix + "  " + m.toString());
+        }
+
+        pw.decreaseIndent();
+    }
+
+
+    private class SimpleSocketCheck implements Closeable {
+        protected final InetAddress mSource;  // Usually null.
+        protected final InetAddress mTarget;
+        protected final int mAddressFamily;
+        protected final Measurement mMeasurement;
+        protected FileDescriptor mFileDescriptor;
+        protected SocketAddress mSocketAddress;
+
+        protected SimpleSocketCheck(
+                InetAddress source, InetAddress target, Measurement measurement) {
+            mMeasurement = measurement;
+
+            if (target instanceof Inet6Address) {
+                Inet6Address targetWithScopeId = null;
+                if (target.isLinkLocalAddress() && mInterfaceIndex != null) {
+                    try {
+                        targetWithScopeId = Inet6Address.getByAddress(
+                                null, target.getAddress(), mInterfaceIndex);
+                    } catch (UnknownHostException e) {
+                        mMeasurement.recordFailure(e.toString());
+                    }
+                }
+                mTarget = (targetWithScopeId != null) ? targetWithScopeId : target;
+                mAddressFamily = AF_INET6;
+            } else {
+                mTarget = target;
+                mAddressFamily = AF_INET;
+            }
+
+            // We don't need to check the scope ID here because we currently only do explicit-source
+            // measurements from global IPv6 addresses.
+            mSource = source;
+        }
+
+        protected SimpleSocketCheck(InetAddress target, Measurement measurement) {
+            this(null, target, measurement);
+        }
+
+        protected void setupSocket(
+                int sockType, int protocol, long writeTimeout, long readTimeout, int dstPort)
+                throws ErrnoException, IOException {
+            final int oldTag = TrafficStats.getAndSetThreadStatsTag(
+                    NetworkStackConstants.TAG_SYSTEM_PROBE);
+            try {
+                mFileDescriptor = Os.socket(mAddressFamily, sockType, protocol);
+            } finally {
+                // TODO: The tag should remain set until all traffic is sent and received.
+                // Consider tagging the socket after the measurement thread is started.
+                TrafficStats.setThreadStatsTag(oldTag);
+            }
+            // Setting SNDTIMEO is purely for defensive purposes.
+            Os.setsockoptTimeval(mFileDescriptor,
+                    SOL_SOCKET, SO_SNDTIMEO, StructTimeval.fromMillis(writeTimeout));
+            Os.setsockoptTimeval(mFileDescriptor,
+                    SOL_SOCKET, SO_RCVTIMEO, StructTimeval.fromMillis(readTimeout));
+            // TODO: Use IP_RECVERR/IPV6_RECVERR, pending OsContants availability.
+            mNetwork.bindSocket(mFileDescriptor);
+            if (mSource != null) {
+                Os.bind(mFileDescriptor, mSource, 0);
+            }
+            Os.connect(mFileDescriptor, mTarget, dstPort);
+            mSocketAddress = Os.getsockname(mFileDescriptor);
+        }
+
+        protected boolean ensureMeasurementNecessary() {
+            if (mMeasurement.finishTime == 0) return false;
+
+            // Countdown latch was not decremented when the measurement failed during setup.
+            mCountDownLatch.countDown();
+            return true;
+        }
+
+        @Override
+        public void close() {
+            IoUtils.closeQuietly(mFileDescriptor);
+        }
+    }
+
+
+    private class IcmpCheck extends SimpleSocketCheck implements Runnable {
+        private static final int TIMEOUT_SEND = 100;
+        private static final int TIMEOUT_RECV = 300;
+        private static final int PACKET_BUFSIZE = 512;
+        private final int mProtocol;
+        private final int mIcmpType;
+
+        public IcmpCheck(InetAddress source, InetAddress target, Measurement measurement) {
+            super(source, target, measurement);
+
+            if (mAddressFamily == AF_INET6) {
+                mProtocol = IPPROTO_ICMPV6;
+                mIcmpType = NetworkConstants.ICMPV6_ECHO_REQUEST_TYPE;
+                mMeasurement.description = "ICMPv6";
+            } else {
+                mProtocol = IPPROTO_ICMP;
+                mIcmpType = NetworkConstants.ICMPV4_ECHO_REQUEST_TYPE;
+                mMeasurement.description = "ICMPv4";
+            }
+
+            mMeasurement.description += " dst{" + mTarget.getHostAddress() + "}";
+        }
+
+        public IcmpCheck(InetAddress target, Measurement measurement) {
+            this(null, target, measurement);
+        }
+
+        @Override
+        public void run() {
+            if (ensureMeasurementNecessary()) return;
+
+            try {
+                setupSocket(SOCK_DGRAM, mProtocol, TIMEOUT_SEND, TIMEOUT_RECV, 0);
+            } catch (ErrnoException | IOException e) {
+                mMeasurement.recordFailure(e.toString());
+                return;
+            }
+            mMeasurement.description += " src{" + socketAddressToString(mSocketAddress) + "}";
+
+            // Build a trivial ICMP packet.
+            final byte[] icmpPacket = {
+                    (byte) mIcmpType, 0, 0, 0, 0, 0, 0, 0  // ICMP header
+            };
+
+            int count = 0;
+            mMeasurement.startTime = now();
+            while (now() < mDeadlineTime - (TIMEOUT_SEND + TIMEOUT_RECV)) {
+                count++;
+                icmpPacket[icmpPacket.length - 1] = (byte) count;
+                try {
+                    Os.write(mFileDescriptor, icmpPacket, 0, icmpPacket.length);
+                } catch (ErrnoException | InterruptedIOException e) {
+                    mMeasurement.recordFailure(e.toString());
+                    break;
+                }
+
+                try {
+                    ByteBuffer reply = ByteBuffer.allocate(PACKET_BUFSIZE);
+                    Os.read(mFileDescriptor, reply);
+                    // TODO: send a few pings back to back to guesstimate packet loss.
+                    mMeasurement.recordSuccess("1/" + count);
+                    break;
+                } catch (ErrnoException | InterruptedIOException e) {
+                    continue;
+                }
+            }
+            if (mMeasurement.finishTime == 0) {
+                mMeasurement.recordFailure("0/" + count);
+            }
+
+            close();
+        }
+    }
+
+
+    private class DnsUdpCheck extends SimpleSocketCheck implements Runnable {
+        private static final int TIMEOUT_SEND = 100;
+        private static final int TIMEOUT_RECV = 500;
+        private static final int RR_TYPE_A = 1;
+        private static final int RR_TYPE_AAAA = 28;
+        private static final int PACKET_BUFSIZE = 512;
+
+        protected final Random mRandom = new Random();
+
+        // Should be static, but the compiler mocks our puny, human attempts at reason.
+        protected String responseCodeStr(int rcode) {
+            try {
+                return DnsResponseCode.values()[rcode].toString();
+            } catch (IndexOutOfBoundsException e) {
+                return String.valueOf(rcode);
+            }
+        }
+
+        protected final int mQueryType;
+
+        public DnsUdpCheck(InetAddress target, Measurement measurement) {
+            super(target, measurement);
+
+            // TODO: Ideally, query the target for both types regardless of address family.
+            if (mAddressFamily == AF_INET6) {
+                mQueryType = RR_TYPE_AAAA;
+            } else {
+                mQueryType = RR_TYPE_A;
+            }
+
+            mMeasurement.description = "DNS UDP dst{" + mTarget.getHostAddress() + "}";
+        }
+
+        @Override
+        public void run() {
+            if (ensureMeasurementNecessary()) return;
+
+            try {
+                setupSocket(SOCK_DGRAM, IPPROTO_UDP, TIMEOUT_SEND, TIMEOUT_RECV,
+                        NetworkConstants.DNS_SERVER_PORT);
+            } catch (ErrnoException | IOException e) {
+                mMeasurement.recordFailure(e.toString());
+                return;
+            }
+
+            // This needs to be fixed length so it can be dropped into the pre-canned packet.
+            final String sixRandomDigits = String.valueOf(mRandom.nextInt(900000) + 100000);
+            appendDnsToMeasurementDescription(sixRandomDigits, mSocketAddress);
+
+            // Build a trivial DNS packet.
+            final byte[] dnsPacket = getDnsQueryPacket(sixRandomDigits);
+
+            int count = 0;
+            mMeasurement.startTime = now();
+            while (now() < mDeadlineTime - (TIMEOUT_RECV + TIMEOUT_RECV)) {
+                count++;
+                try {
+                    Os.write(mFileDescriptor, dnsPacket, 0, dnsPacket.length);
+                } catch (ErrnoException | InterruptedIOException e) {
+                    mMeasurement.recordFailure(e.toString());
+                    break;
+                }
+
+                try {
+                    ByteBuffer reply = ByteBuffer.allocate(PACKET_BUFSIZE);
+                    Os.read(mFileDescriptor, reply);
+                    // TODO: more correct and detailed evaluation of the response,
+                    // possibly adding the returned IP address(es) to the output.
+                    final String rcodeStr = (reply.limit() > 3)
+                            ? " " + responseCodeStr((int) (reply.get(3)) & 0x0f)
+                            : "";
+                    mMeasurement.recordSuccess("1/" + count + rcodeStr);
+                    break;
+                } catch (ErrnoException | InterruptedIOException e) {
+                    continue;
+                }
+            }
+            if (mMeasurement.finishTime == 0) {
+                mMeasurement.recordFailure("0/" + count);
+            }
+
+            close();
+        }
+
+        protected byte[] getDnsQueryPacket(String sixRandomDigits) {
+            byte[] rnd = sixRandomDigits.getBytes(StandardCharsets.US_ASCII);
+            return new byte[] {
+                (byte) mRandom.nextInt(), (byte) mRandom.nextInt(),  // [0-1]   query ID
+                1, 0,  // [2-3]   flags; byte[2] = 1 for recursion desired (RD).
+                0, 1,  // [4-5]   QDCOUNT (number of queries)
+                0, 0,  // [6-7]   ANCOUNT (number of answers)
+                0, 0,  // [8-9]   NSCOUNT (number of name server records)
+                0, 0,  // [10-11] ARCOUNT (number of additional records)
+                17, rnd[0], rnd[1], rnd[2], rnd[3], rnd[4], rnd[5],
+                        '-', 'a', 'n', 'd', 'r', 'o', 'i', 'd', '-', 'd', 's',
+                6, 'm', 'e', 't', 'r', 'i', 'c',
+                7, 'g', 's', 't', 'a', 't', 'i', 'c',
+                3, 'c', 'o', 'm',
+                0,  // null terminator of FQDN (root TLD)
+                0, (byte) mQueryType,  // QTYPE
+                0, 1  // QCLASS, set to 1 = IN (Internet)
+            };
+        }
+
+        protected void appendDnsToMeasurementDescription(
+                String sixRandomDigits, SocketAddress sockAddr) {
+            mMeasurement.description += " src{" + socketAddressToString(sockAddr) + "}"
+                    + " qtype{" + mQueryType + "}"
+                    + " qname{" + sixRandomDigits + "-android-ds.metric.gstatic.com}";
+        }
+    }
+
+    // TODO: Have it inherited from SimpleSocketCheck, and separate common DNS helpers out of
+    // DnsUdpCheck.
+    private class DnsTlsCheck extends DnsUdpCheck {
+        private static final int TCP_CONNECT_TIMEOUT_MS = 2500;
+        private static final int TCP_TIMEOUT_MS = 2000;
+        private static final int DNS_TLS_PORT = 853;
+        private static final int DNS_HEADER_SIZE = 12;
+
+        private final String mHostname;
+
+        public DnsTlsCheck(@Nullable String hostname, @NonNull InetAddress target,
+                @NonNull Measurement measurement) {
+            super(target, measurement);
+
+            mHostname = hostname;
+            mMeasurement.description = "DNS TLS dst{" + mTarget.getHostAddress() + "} hostname{"
+                    + (mHostname == null ? "" : mHostname) + "}";
+        }
+
+        private SSLSocket setupSSLSocket() throws IOException {
+            // A TrustManager will be created and initialized with a KeyStore containing system
+            // CaCerts. During SSL handshake, it will be used to validate the certificates from
+            // the server.
+            SSLSocket sslSocket = (SSLSocket) SSLSocketFactory.getDefault().createSocket();
+            sslSocket.setSoTimeout(TCP_TIMEOUT_MS);
+
+            if (!TextUtils.isEmpty(mHostname)) {
+                // Set SNI.
+                final List<SNIServerName> names =
+                        Collections.singletonList(new SNIHostName(mHostname));
+                SSLParameters params = sslSocket.getSSLParameters();
+                params.setServerNames(names);
+                sslSocket.setSSLParameters(params);
+            }
+
+            mNetwork.bindSocket(sslSocket);
+            return sslSocket;
+        }
+
+        private void sendDoTProbe(@Nullable SSLSocket sslSocket) throws IOException {
+            final String sixRandomDigits = String.valueOf(mRandom.nextInt(900000) + 100000);
+            final byte[] dnsPacket = getDnsQueryPacket(sixRandomDigits);
+
+            mMeasurement.startTime = now();
+            sslSocket.connect(new InetSocketAddress(mTarget, DNS_TLS_PORT), TCP_CONNECT_TIMEOUT_MS);
+
+            // Synchronous call waiting for the TLS handshake complete.
+            sslSocket.startHandshake();
+            appendDnsToMeasurementDescription(sixRandomDigits, sslSocket.getLocalSocketAddress());
+
+            final DataOutputStream output = new DataOutputStream(sslSocket.getOutputStream());
+            output.writeShort(dnsPacket.length);
+            output.write(dnsPacket, 0, dnsPacket.length);
+
+            final DataInputStream input = new DataInputStream(sslSocket.getInputStream());
+            final int replyLength = Short.toUnsignedInt(input.readShort());
+            final byte[] reply = new byte[replyLength];
+            int bytesRead = 0;
+            while (bytesRead < replyLength) {
+                bytesRead += input.read(reply, bytesRead, replyLength - bytesRead);
+            }
+
+            if (bytesRead > DNS_HEADER_SIZE && bytesRead == replyLength) {
+                mMeasurement.recordSuccess("1/1 " + responseCodeStr((int) (reply[3]) & 0x0f));
+            } else {
+                mMeasurement.recordFailure("1/1 Read " + bytesRead + " bytes while expected to be "
+                        + replyLength + " bytes");
+            }
+        }
+
+        @Override
+        public void run() {
+            if (ensureMeasurementNecessary()) return;
+
+            // No need to restore the tag, since this thread is only used for this measurement.
+            TrafficStats.getAndSetThreadStatsTag(NetworkStackConstants.TAG_SYSTEM_PROBE);
+
+            try (SSLSocket sslSocket = setupSSLSocket()) {
+                sendDoTProbe(sslSocket);
+            } catch (IOException e) {
+                mMeasurement.recordFailure(e.toString());
+            }
+        }
+    }
+}
diff --git a/service/src/com/android/server/connectivity/NetworkNotificationManager.java b/service/src/com/android/server/connectivity/NetworkNotificationManager.java
new file mode 100644
index 0000000..3dc79c5
--- /dev/null
+++ b/service/src/com/android/server/connectivity/NetworkNotificationManager.java
@@ -0,0 +1,404 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET;
+import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
+import static android.net.NetworkCapabilities.TRANSPORT_VPN;
+import static android.net.NetworkCapabilities.TRANSPORT_WIFI;
+
+import android.annotation.NonNull;
+import android.app.Notification;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.content.Context;
+import android.content.Intent;
+import android.content.res.Resources;
+import android.graphics.drawable.Icon;
+import android.net.ConnectivityResources;
+import android.net.NetworkSpecifier;
+import android.net.TelephonyNetworkSpecifier;
+import android.net.wifi.WifiInfo;
+import android.os.UserHandle;
+import android.telephony.SubscriptionManager;
+import android.telephony.TelephonyManager;
+import android.text.TextUtils;
+import android.util.Log;
+import android.util.SparseArray;
+import android.util.SparseIntArray;
+import android.widget.Toast;
+
+import com.android.connectivity.resources.R;
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.messages.nano.SystemMessageProto.SystemMessage;
+
+public class NetworkNotificationManager {
+
+
+    public static enum NotificationType {
+        LOST_INTERNET(SystemMessage.NOTE_NETWORK_LOST_INTERNET),
+        NETWORK_SWITCH(SystemMessage.NOTE_NETWORK_SWITCH),
+        NO_INTERNET(SystemMessage.NOTE_NETWORK_NO_INTERNET),
+        PARTIAL_CONNECTIVITY(SystemMessage.NOTE_NETWORK_PARTIAL_CONNECTIVITY),
+        SIGN_IN(SystemMessage.NOTE_NETWORK_SIGN_IN),
+        PRIVATE_DNS_BROKEN(SystemMessage.NOTE_NETWORK_PRIVATE_DNS_BROKEN);
+
+        public final int eventId;
+
+        NotificationType(int eventId) {
+            this.eventId = eventId;
+            Holder.sIdToTypeMap.put(eventId, this);
+        }
+
+        private static class Holder {
+            private static SparseArray<NotificationType> sIdToTypeMap = new SparseArray<>();
+        }
+
+        public static NotificationType getFromId(int id) {
+            return Holder.sIdToTypeMap.get(id);
+        }
+    };
+
+    private static final String TAG = NetworkNotificationManager.class.getSimpleName();
+    private static final boolean DBG = true;
+
+    // Notification channels used by ConnectivityService mainline module, it should be aligned with
+    // SystemNotificationChannels so the channels are the same as the ones used as the system
+    // server.
+    public static final String NOTIFICATION_CHANNEL_NETWORK_STATUS = "NETWORK_STATUS";
+    public static final String NOTIFICATION_CHANNEL_NETWORK_ALERTS = "NETWORK_ALERTS";
+
+    // The context is for the current user (system server)
+    private final Context mContext;
+    private final ConnectivityResources mResources;
+    private final TelephonyManager mTelephonyManager;
+    // The notification manager is created from a context for User.ALL, so notifications
+    // will be sent to all users.
+    private final NotificationManager mNotificationManager;
+    // Tracks the types of notifications managed by this instance, from creation to cancellation.
+    private final SparseIntArray mNotificationTypeMap;
+
+    public NetworkNotificationManager(@NonNull final Context c, @NonNull final TelephonyManager t) {
+        mContext = c;
+        mTelephonyManager = t;
+        mNotificationManager =
+                (NotificationManager) c.createContextAsUser(UserHandle.ALL, 0 /* flags */)
+                        .getSystemService(Context.NOTIFICATION_SERVICE);
+        mNotificationTypeMap = new SparseIntArray();
+        mResources = new ConnectivityResources(mContext);
+    }
+
+    @VisibleForTesting
+    protected static int approximateTransportType(NetworkAgentInfo nai) {
+        return nai.isVPN() ? TRANSPORT_VPN : getFirstTransportType(nai);
+    }
+
+    // TODO: deal more gracefully with multi-transport networks.
+    private static int getFirstTransportType(NetworkAgentInfo nai) {
+        // TODO: The range is wrong, the safer and correct way is to change the range from
+        // MIN_TRANSPORT to MAX_TRANSPORT.
+        for (int i = 0; i < 64; i++) {
+            if (nai.networkCapabilities.hasTransport(i)) return i;
+        }
+        return -1;
+    }
+
+    private String getTransportName(final int transportType) {
+        String[] networkTypes = mResources.get().getStringArray(R.array.network_switch_type_name);
+        try {
+            return networkTypes[transportType];
+        } catch (IndexOutOfBoundsException e) {
+            return mResources.get().getString(R.string.network_switch_type_name_unknown);
+        }
+    }
+
+    private static int getIcon(int transportType) {
+        return (transportType == TRANSPORT_WIFI)
+                ? R.drawable.stat_notify_wifi_in_range  // TODO: Distinguish ! from ?.
+                : R.drawable.stat_notify_rssi_in_range;
+    }
+
+    /**
+     * Show or hide network provisioning notifications.
+     *
+     * We use notifications for two purposes: to notify that a network requires sign in
+     * (NotificationType.SIGN_IN), or to notify that a network does not have Internet access
+     * (NotificationType.NO_INTERNET). We display at most one notification per ID, so on a
+     * particular network we can display the notification type that was most recently requested.
+     * So for example if a captive portal fails to reply within a few seconds of connecting, we
+     * might first display NO_INTERNET, and then when the captive portal check completes, display
+     * SIGN_IN.
+     *
+     * @param id an identifier that uniquely identifies this notification.  This must match
+     *         between show and hide calls.  We use the NetID value but for legacy callers
+     *         we concatenate the range of types with the range of NetIDs.
+     * @param notifyType the type of the notification.
+     * @param nai the network with which the notification is associated. For a SIGN_IN, NO_INTERNET,
+     *         or LOST_INTERNET notification, this is the network we're connecting to. For a
+     *         NETWORK_SWITCH notification it's the network that we switched from. When this network
+     *         disconnects the notification is removed.
+     * @param switchToNai for a NETWORK_SWITCH notification, the network we are switching to. Null
+     *         in all other cases. Only used to determine the text of the notification.
+     */
+    public void showNotification(int id, NotificationType notifyType, NetworkAgentInfo nai,
+            NetworkAgentInfo switchToNai, PendingIntent intent, boolean highPriority) {
+        final String tag = tagFor(id);
+        final int eventId = notifyType.eventId;
+        final int transportType;
+        final CharSequence name;
+        if (nai != null) {
+            transportType = approximateTransportType(nai);
+            final String extraInfo = nai.networkInfo.getExtraInfo();
+            if (nai.linkProperties != null && nai.linkProperties.getCaptivePortalData() != null
+                    && !TextUtils.isEmpty(nai.linkProperties.getCaptivePortalData()
+                    .getVenueFriendlyName())) {
+                name = nai.linkProperties.getCaptivePortalData().getVenueFriendlyName();
+            } else {
+                name = TextUtils.isEmpty(extraInfo)
+                        ? WifiInfo.sanitizeSsid(nai.networkCapabilities.getSsid()) : extraInfo;
+            }
+            // Only notify for Internet-capable networks.
+            if (!nai.networkCapabilities.hasCapability(NET_CAPABILITY_INTERNET)) return;
+        } else {
+            // Legacy notifications.
+            transportType = TRANSPORT_CELLULAR;
+            name = "";
+        }
+
+        // Clear any previous notification with lower priority, otherwise return. http://b/63676954.
+        // A new SIGN_IN notification with a new intent should override any existing one.
+        final int previousEventId = mNotificationTypeMap.get(id);
+        final NotificationType previousNotifyType = NotificationType.getFromId(previousEventId);
+        if (priority(previousNotifyType) > priority(notifyType)) {
+            Log.d(TAG, String.format(
+                    "ignoring notification %s for network %s with existing notification %s",
+                    notifyType, id, previousNotifyType));
+            return;
+        }
+        clearNotification(id);
+
+        if (DBG) {
+            Log.d(TAG, String.format(
+                    "showNotification tag=%s event=%s transport=%s name=%s highPriority=%s",
+                    tag, nameOf(eventId), getTransportName(transportType), name, highPriority));
+        }
+
+        final Resources r = mResources.get();
+        final CharSequence title;
+        final CharSequence details;
+        Icon icon = Icon.createWithResource(
+                mResources.getResourcesContext(), getIcon(transportType));
+        if (notifyType == NotificationType.NO_INTERNET && transportType == TRANSPORT_WIFI) {
+            title = r.getString(R.string.wifi_no_internet, name);
+            details = r.getString(R.string.wifi_no_internet_detailed);
+        } else if (notifyType == NotificationType.PRIVATE_DNS_BROKEN) {
+            if (transportType == TRANSPORT_CELLULAR) {
+                title = r.getString(R.string.mobile_no_internet);
+            } else if (transportType == TRANSPORT_WIFI) {
+                title = r.getString(R.string.wifi_no_internet, name);
+            } else {
+                title = r.getString(R.string.other_networks_no_internet);
+            }
+            details = r.getString(R.string.private_dns_broken_detailed);
+        } else if (notifyType == NotificationType.PARTIAL_CONNECTIVITY
+                && transportType == TRANSPORT_WIFI) {
+            title = r.getString(R.string.network_partial_connectivity, name);
+            details = r.getString(R.string.network_partial_connectivity_detailed);
+        } else if (notifyType == NotificationType.LOST_INTERNET &&
+                transportType == TRANSPORT_WIFI) {
+            title = r.getString(R.string.wifi_no_internet, name);
+            details = r.getString(R.string.wifi_no_internet_detailed);
+        } else if (notifyType == NotificationType.SIGN_IN) {
+            switch (transportType) {
+                case TRANSPORT_WIFI:
+                    title = r.getString(R.string.wifi_available_sign_in, 0);
+                    details = r.getString(R.string.network_available_sign_in_detailed, name);
+                    break;
+                case TRANSPORT_CELLULAR:
+                    title = r.getString(R.string.network_available_sign_in, 0);
+                    // TODO: Change this to pull from NetworkInfo once a printable
+                    // name has been added to it
+                    NetworkSpecifier specifier = nai.networkCapabilities.getNetworkSpecifier();
+                    int subId = SubscriptionManager.DEFAULT_SUBSCRIPTION_ID;
+                    if (specifier instanceof TelephonyNetworkSpecifier) {
+                        subId = ((TelephonyNetworkSpecifier) specifier).getSubscriptionId();
+                    }
+
+                    details = mTelephonyManager.createForSubscriptionId(subId)
+                            .getNetworkOperatorName();
+                    break;
+                default:
+                    title = r.getString(R.string.network_available_sign_in, 0);
+                    details = r.getString(R.string.network_available_sign_in_detailed, name);
+                    break;
+            }
+        } else if (notifyType == NotificationType.NETWORK_SWITCH) {
+            String fromTransport = getTransportName(transportType);
+            String toTransport = getTransportName(approximateTransportType(switchToNai));
+            title = r.getString(R.string.network_switch_metered, toTransport);
+            details = r.getString(R.string.network_switch_metered_detail, toTransport,
+                    fromTransport);
+        } else if (notifyType == NotificationType.NO_INTERNET
+                    || notifyType == NotificationType.PARTIAL_CONNECTIVITY) {
+            // NO_INTERNET and PARTIAL_CONNECTIVITY notification for non-WiFi networks
+            // are sent, but they are not implemented yet.
+            return;
+        } else {
+            Log.wtf(TAG, "Unknown notification type " + notifyType + " on network transport "
+                    + getTransportName(transportType));
+            return;
+        }
+        // When replacing an existing notification for a given network, don't alert, just silently
+        // update the existing notification. Note that setOnlyAlertOnce() will only work for the
+        // same id, and the id used here is the NotificationType which is different in every type of
+        // notification. This is required because the notification metrics only track the ID but not
+        // the tag.
+        final boolean hasPreviousNotification = previousNotifyType != null;
+        final String channelId = (highPriority && !hasPreviousNotification)
+                ? NOTIFICATION_CHANNEL_NETWORK_ALERTS : NOTIFICATION_CHANNEL_NETWORK_STATUS;
+        Notification.Builder builder = new Notification.Builder(mContext, channelId)
+                .setWhen(System.currentTimeMillis())
+                .setShowWhen(notifyType == NotificationType.NETWORK_SWITCH)
+                .setSmallIcon(icon)
+                .setAutoCancel(true)
+                .setTicker(title)
+                .setColor(mContext.getColor(android.R.color.system_notification_accent_color))
+                .setContentTitle(title)
+                .setContentIntent(intent)
+                .setLocalOnly(true)
+                .setOnlyAlertOnce(true)
+                // TODO: consider having action buttons to disconnect on the sign-in notification
+                // especially if it is ongoing
+                .setOngoing(notifyType == NotificationType.SIGN_IN
+                        && r.getBoolean(R.bool.config_ongoingSignInNotification));
+
+        if (notifyType == NotificationType.NETWORK_SWITCH) {
+            builder.setStyle(new Notification.BigTextStyle().bigText(details));
+        } else {
+            builder.setContentText(details);
+        }
+
+        if (notifyType == NotificationType.SIGN_IN) {
+            builder.extend(new Notification.TvExtender().setChannelId(channelId));
+        }
+
+        Notification notification = builder.build();
+
+        mNotificationTypeMap.put(id, eventId);
+        try {
+            mNotificationManager.notify(tag, eventId, notification);
+        } catch (NullPointerException npe) {
+            Log.d(TAG, "setNotificationVisible: visible notificationManager error", npe);
+        }
+    }
+
+    /**
+     * Clear the notification with the given id, only if it matches the given type.
+     */
+    public void clearNotification(int id, NotificationType notifyType) {
+        final int previousEventId = mNotificationTypeMap.get(id);
+        final NotificationType previousNotifyType = NotificationType.getFromId(previousEventId);
+        if (notifyType != previousNotifyType) {
+            return;
+        }
+        clearNotification(id);
+    }
+
+    public void clearNotification(int id) {
+        if (mNotificationTypeMap.indexOfKey(id) < 0) {
+            return;
+        }
+        final String tag = tagFor(id);
+        final int eventId = mNotificationTypeMap.get(id);
+        if (DBG) {
+            Log.d(TAG, String.format("clearing notification tag=%s event=%s", tag,
+                   nameOf(eventId)));
+        }
+        try {
+            mNotificationManager.cancel(tag, eventId);
+        } catch (NullPointerException npe) {
+            Log.d(TAG, String.format(
+                    "failed to clear notification tag=%s event=%s", tag, nameOf(eventId)), npe);
+        }
+        mNotificationTypeMap.delete(id);
+    }
+
+    /**
+     * Legacy provisioning notifications coming directly from DcTracker.
+     */
+    public void setProvNotificationVisible(boolean visible, int id, String action) {
+        if (visible) {
+            // For legacy purposes, action is sent as the action + the phone ID from DcTracker.
+            // Split the string here and send the phone ID as an extra instead.
+            String[] splitAction = action.split(":");
+            Intent intent = new Intent(splitAction[0]);
+            try {
+                intent.putExtra("provision.phone.id", Integer.parseInt(splitAction[1]));
+            } catch (NumberFormatException ignored) { }
+            PendingIntent pendingIntent = PendingIntent.getBroadcast(
+                    mContext, 0 /* requestCode */, intent, PendingIntent.FLAG_IMMUTABLE);
+            showNotification(id, NotificationType.SIGN_IN, null, null, pendingIntent, false);
+        } else {
+            clearNotification(id);
+        }
+    }
+
+    public void showToast(NetworkAgentInfo fromNai, NetworkAgentInfo toNai) {
+        String fromTransport = getTransportName(approximateTransportType(fromNai));
+        String toTransport = getTransportName(approximateTransportType(toNai));
+        String text = mResources.get().getString(
+                R.string.network_switch_metered_toast, fromTransport, toTransport);
+        Toast.makeText(mContext, text, Toast.LENGTH_LONG).show();
+    }
+
+    @VisibleForTesting
+    static String tagFor(int id) {
+        return String.format("ConnectivityNotification:%d", id);
+    }
+
+    @VisibleForTesting
+    static String nameOf(int eventId) {
+        NotificationType t = NotificationType.getFromId(eventId);
+        return (t != null) ? t.name() : "UNKNOWN";
+    }
+
+    /**
+     * A notification with a higher number will take priority over a notification with a lower
+     * number.
+     */
+    private static int priority(NotificationType t) {
+        if (t == null) {
+            return 0;
+        }
+        switch (t) {
+            case SIGN_IN:
+                return 6;
+            case PARTIAL_CONNECTIVITY:
+                return 5;
+            case PRIVATE_DNS_BROKEN:
+                return 4;
+            case NO_INTERNET:
+                return 3;
+            case NETWORK_SWITCH:
+                return 2;
+            case LOST_INTERNET:
+                return 1;
+            default:
+                return 0;
+        }
+    }
+}
diff --git a/service/src/com/android/server/connectivity/NetworkOffer.java b/service/src/com/android/server/connectivity/NetworkOffer.java
new file mode 100644
index 0000000..8285e7a
--- /dev/null
+++ b/service/src/com/android/server/connectivity/NetworkOffer.java
@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import android.annotation.NonNull;
+import android.net.INetworkOfferCallback;
+import android.net.NetworkCapabilities;
+import android.net.NetworkRequest;
+import android.os.RemoteException;
+
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * Represents an offer made by a NetworkProvider to create a network if a need arises.
+ *
+ * This class contains the prospective score and capabilities of the network. The provider
+ * is not obligated to caps able to create a network satisfying this, nor to build a network
+ * with the exact score and/or capabilities passed ; after all, not all providers know in
+ * advance what a network will look like after it's connected. Instead, this is meant as a
+ * filter to limit requests sent to the provider by connectivity to those that this offer stands
+ * a chance to fulfill.
+ *
+ * @see NetworkProvider#offerNetwork.
+ *
+ * @hide
+ */
+public class NetworkOffer implements NetworkRanker.Scoreable {
+    @NonNull public final FullScore score;
+    @NonNull public final NetworkCapabilities caps;
+    @NonNull public final INetworkOfferCallback callback;
+    @NonNull public final int providerId;
+    // While this could, in principle, be deduced from the old values of the satisfying networks,
+    // doing so would add a lot of complexity and performance penalties. For each request, the
+    // ranker would have to run again to figure out if this offer used to be able to beat the
+    // previous satisfier to know if there is a change in whether this offer is now needed ;
+    // besides, there would be a need to handle an edge case when a new request comes online,
+    // where it's not satisfied before the first rematch, where starting to satisfy a request
+    // should not result in sending unneeded to this offer. This boolean, while requiring that
+    // the offers are only ever manipulated on the CS thread, is by far a simpler and
+    // economical solution.
+    private final Set<NetworkRequest> mCurrentlyNeeded = new HashSet<>();
+
+    public NetworkOffer(@NonNull final FullScore score,
+            @NonNull final NetworkCapabilities caps,
+            @NonNull final INetworkOfferCallback callback,
+            @NonNull final int providerId) {
+        this.score = Objects.requireNonNull(score);
+        this.caps = Objects.requireNonNull(caps);
+        this.callback = Objects.requireNonNull(callback);
+        this.providerId = providerId;
+    }
+
+    /**
+     * Get the score filter of this offer
+     */
+    @Override @NonNull public FullScore getScore() {
+        return score;
+    }
+
+    /**
+     * Get the capabilities filter of this offer
+     */
+    @Override @NonNull public NetworkCapabilities getCapsNoCopy() {
+        return caps;
+    }
+
+    /**
+     * Tell the provider for this offer that the network is needed for a request.
+     * @param request the request for which the offer is needed
+     */
+    public void onNetworkNeeded(@NonNull final NetworkRequest request) {
+        if (mCurrentlyNeeded.contains(request)) {
+            throw new IllegalStateException("Network already needed");
+        }
+        mCurrentlyNeeded.add(request);
+        try {
+            callback.onNetworkNeeded(request);
+        } catch (final RemoteException e) {
+            // The provider is dead. It will be removed by the death recipient.
+        }
+    }
+
+    /**
+     * Tell the provider for this offer that the network is no longer needed for this request.
+     *
+     * onNetworkNeeded will have been called with the same request before.
+     *
+     * @param request the request
+     */
+    public void onNetworkUnneeded(@NonNull final NetworkRequest request) {
+        if (!mCurrentlyNeeded.contains(request)) {
+            throw new IllegalStateException("Network already unneeded");
+        }
+        mCurrentlyNeeded.remove(request);
+        try {
+            callback.onNetworkUnneeded(request);
+        } catch (final RemoteException e) {
+            // The provider is dead. It will be removed by the death recipient.
+        }
+    }
+
+    /**
+     * Returns whether this offer is currently needed for this request.
+     * @param request the request
+     * @return whether the offer is currently considered needed
+     */
+    public boolean neededFor(@NonNull final NetworkRequest request) {
+        return mCurrentlyNeeded.contains(request);
+    }
+
+    /**
+     * Migrate from, and take over, a previous offer.
+     *
+     * When an updated offer is sent from a provider, call this method on the new offer, passing
+     * the old one, to take over the state.
+     *
+     * @param previousOffer the previous offer
+     */
+    public void migrateFrom(@NonNull final NetworkOffer previousOffer) {
+        if (!callback.asBinder().equals(previousOffer.callback.asBinder())) {
+            throw new IllegalArgumentException("Can only migrate from a previous version of"
+                    + " the same offer");
+        }
+        mCurrentlyNeeded.clear();
+        mCurrentlyNeeded.addAll(previousOffer.mCurrentlyNeeded);
+    }
+
+    @Override
+    public String toString() {
+        return "NetworkOffer [ Score " + score + " ]";
+    }
+}
diff --git a/service/src/com/android/server/connectivity/NetworkRanker.java b/service/src/com/android/server/connectivity/NetworkRanker.java
new file mode 100644
index 0000000..e839837
--- /dev/null
+++ b/service/src/com/android/server/connectivity/NetworkRanker.java
@@ -0,0 +1,299 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.net.NetworkCapabilities.TRANSPORT_BLUETOOTH;
+import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
+import static android.net.NetworkCapabilities.TRANSPORT_ETHERNET;
+import static android.net.NetworkCapabilities.TRANSPORT_WIFI;
+import static android.net.NetworkScore.POLICY_EXITING;
+import static android.net.NetworkScore.POLICY_TRANSPORT_PRIMARY;
+import static android.net.NetworkScore.POLICY_YIELD_TO_BAD_WIFI;
+
+import static com.android.net.module.util.CollectionUtils.filter;
+import static com.android.server.connectivity.FullScore.POLICY_ACCEPT_UNVALIDATED;
+import static com.android.server.connectivity.FullScore.POLICY_EVER_USER_SELECTED;
+import static com.android.server.connectivity.FullScore.POLICY_EVER_VALIDATED_NOT_AVOIDED_WHEN_BAD;
+import static com.android.server.connectivity.FullScore.POLICY_IS_INVINCIBLE;
+import static com.android.server.connectivity.FullScore.POLICY_IS_VALIDATED;
+import static com.android.server.connectivity.FullScore.POLICY_IS_VPN;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.net.NetworkCapabilities;
+import android.net.NetworkRequest;
+
+import com.android.net.module.util.CollectionUtils;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+import java.util.function.Predicate;
+
+/**
+ * A class that knows how to find the best network matching a request out of a list of networks.
+ */
+public class NetworkRanker {
+    // Historically the legacy ints have been 0~100 in principle (though the highest score in
+    // AOSP has always been 90). This is relied on by VPNs that send a legacy score of 101.
+    public static final int LEGACY_INT_MAX = 100;
+
+    /**
+     * A class that can be scored against other scoreables.
+     */
+    public interface Scoreable {
+        /** Get score of this scoreable */
+        FullScore getScore();
+        /** Get capabilities of this scoreable */
+        NetworkCapabilities getCapsNoCopy();
+    }
+
+    private static final boolean USE_POLICY_RANKING = true;
+
+    public NetworkRanker() { }
+
+    /**
+     * Find the best network satisfying this request among the list of passed networks.
+     */
+    @Nullable
+    public NetworkAgentInfo getBestNetwork(@NonNull final NetworkRequest request,
+            @NonNull final Collection<NetworkAgentInfo> nais,
+            @Nullable final NetworkAgentInfo currentSatisfier) {
+        final ArrayList<NetworkAgentInfo> candidates = filter(nais, nai -> nai.satisfies(request));
+        if (candidates.size() == 1) return candidates.get(0); // Only one potential satisfier
+        if (candidates.size() <= 0) return null; // No network can satisfy this request
+        if (USE_POLICY_RANKING) {
+            return getBestNetworkByPolicy(candidates, currentSatisfier);
+        } else {
+            return getBestNetworkByLegacyInt(candidates);
+        }
+    }
+
+    // Transport preference order, if it comes down to that.
+    private static final int[] PREFERRED_TRANSPORTS_ORDER = { TRANSPORT_ETHERNET, TRANSPORT_WIFI,
+            TRANSPORT_BLUETOOTH, TRANSPORT_CELLULAR };
+
+    // Function used to partition a list into two working areas depending on whether they
+    // satisfy a predicate. All items satisfying the predicate will be put in |positive|, all
+    // items that don't will be put in |negative|.
+    // This is useful in this file because many of the ranking checks will retain only networks that
+    // satisfy a predicate if any of them do, but keep them all if all of them do. Having working
+    // areas is uncustomary in Java, but this function is called in a fairly intensive manner
+    // and doing allocation quite that often might affect performance quite badly.
+    private static <T> void partitionInto(@NonNull final List<T> source, @NonNull Predicate<T> test,
+            @NonNull final List<T> positive, @NonNull final List<T> negative) {
+        positive.clear();
+        negative.clear();
+        for (final T item : source) {
+            if (test.test(item)) {
+                positive.add(item);
+            } else {
+                negative.add(item);
+            }
+        }
+    }
+
+    @Nullable private <T extends Scoreable> T getBestNetworkByPolicy(
+            @NonNull List<T> candidates,
+            @Nullable final T currentSatisfier) {
+        // Used as working areas.
+        final ArrayList<T> accepted =
+                new ArrayList<>(candidates.size() /* initialCapacity */);
+        final ArrayList<T> rejected =
+                new ArrayList<>(candidates.size() /* initialCapacity */);
+
+        // The following tests will search for a network matching a given criterion. They all
+        // function the same way : if any network matches the criterion, drop from consideration
+        // all networks that don't. To achieve this, the tests below :
+        // 1. partition the list of remaining candidates into accepted and rejected networks.
+        // 2. if only one candidate remains, that's the winner : if accepted.size == 1 return [0]
+        // 3. if multiple remain, keep only the accepted networks and go on to the next criterion.
+        //    Because the working areas will be wiped, a copy of the accepted networks needs to be
+        //    made.
+        // 4. if none remain, the criterion did not help discriminate so keep them all. As an
+        //    optimization, skip creating a new array and go on to the next criterion.
+
+        // If a network is invincible, use it.
+        partitionInto(candidates, nai -> nai.getScore().hasPolicy(POLICY_IS_INVINCIBLE),
+                accepted, rejected);
+        if (accepted.size() == 1) return accepted.get(0);
+        if (accepted.size() > 0 && rejected.size() > 0) candidates = new ArrayList<>(accepted);
+
+        // If there is a connected VPN, use it.
+        partitionInto(candidates, nai -> nai.getScore().hasPolicy(POLICY_IS_VPN),
+                accepted, rejected);
+        if (accepted.size() == 1) return accepted.get(0);
+        if (accepted.size() > 0 && rejected.size() > 0) candidates = new ArrayList<>(accepted);
+
+        // Selected & Accept-unvalidated policy : if any network has both of these, then don't
+        // choose one that doesn't.
+        partitionInto(candidates, nai -> nai.getScore().hasPolicy(POLICY_EVER_USER_SELECTED)
+                        && nai.getScore().hasPolicy(POLICY_ACCEPT_UNVALIDATED),
+                accepted, rejected);
+        if (accepted.size() == 1) return accepted.get(0);
+        if (accepted.size() > 0 && rejected.size() > 0) candidates = new ArrayList<>(accepted);
+
+        // Yield to bad wifi policy : if any wifi has ever been validated (even if it's now
+        // unvalidated), and unless it's been explicitly avoided when bad in UI, then keep only
+        // networks that don't yield to such a wifi network.
+        final boolean anyWiFiEverValidated = CollectionUtils.any(candidates,
+                nai -> nai.getScore().hasPolicy(POLICY_EVER_VALIDATED_NOT_AVOIDED_WHEN_BAD)
+                        && nai.getCapsNoCopy().hasTransport(TRANSPORT_WIFI));
+        if (anyWiFiEverValidated) {
+            partitionInto(candidates, nai -> !nai.getScore().hasPolicy(POLICY_YIELD_TO_BAD_WIFI),
+                    accepted, rejected);
+            if (accepted.size() == 1) return accepted.get(0);
+            if (accepted.size() > 0 && rejected.size() > 0) candidates = new ArrayList<>(accepted);
+        }
+
+        // If any network is validated (or should be accepted even if it's not validated), then
+        // don't choose one that isn't.
+        partitionInto(candidates, nai -> nai.getScore().hasPolicy(POLICY_IS_VALIDATED)
+                        || nai.getScore().hasPolicy(POLICY_ACCEPT_UNVALIDATED),
+                accepted, rejected);
+        if (accepted.size() == 1) return accepted.get(0);
+        if (accepted.size() > 0 && rejected.size() > 0) candidates = new ArrayList<>(accepted);
+
+        // If any network is not exiting, don't choose one that is.
+        partitionInto(candidates, nai -> !nai.getScore().hasPolicy(POLICY_EXITING),
+                accepted, rejected);
+        if (accepted.size() == 1) return accepted.get(0);
+        if (accepted.size() > 0 && rejected.size() > 0) candidates = new ArrayList<>(accepted);
+
+        // TODO : If any network is unmetered, don't choose a metered network.
+        // This can't be implemented immediately because prospective networks are always
+        // considered unmetered because factories don't know if the network will be metered.
+        // Saying an unmetered network always beats a metered one would mean that when metered wifi
+        // is connected, the offer for telephony would beat WiFi but the actual metered network
+        // would lose, so we'd have an infinite loop where telephony would continually bring up
+        // a network that is immediately torn down.
+        // Fix this by getting the agent to tell connectivity whether the network they will
+        // bring up is metered. Cell knows that in advance, while WiFi has a good estimate and
+        // can revise it if the network later turns out to be metered.
+        // partitionInto(candidates, nai -> nai.getScore().hasPolicy(POLICY_IS_UNMETERED),
+        //         accepted, rejected);
+        // if (accepted.size() == 1) return accepted.get(0);
+        // if (accepted.size() > 0 && rejected.size() > 0) candidates = new ArrayList<>(accepted);
+
+        // If any network is for the default subscription, don't choose a network for another
+        // subscription with the same transport.
+        partitionInto(candidates, nai -> nai.getScore().hasPolicy(POLICY_TRANSPORT_PRIMARY),
+                accepted, rejected);
+        for (final Scoreable defaultSubNai : accepted) {
+            // Remove all networks without the DEFAULT_SUBSCRIPTION policy and the same transports
+            // as a network that has it.
+            final int[] transports = defaultSubNai.getCapsNoCopy().getTransportTypes();
+            candidates.removeIf(nai -> !nai.getScore().hasPolicy(POLICY_TRANSPORT_PRIMARY)
+                    && Arrays.equals(transports, nai.getCapsNoCopy().getTransportTypes()));
+        }
+        if (1 == candidates.size()) return candidates.get(0);
+        // It's guaranteed candidates.size() > 0 because there is at least one with the
+        // TRANSPORT_PRIMARY policy and only those without it were removed.
+
+        // If some of the networks have a better transport than others, keep only the ones with
+        // the best transports.
+        for (final int transport : PREFERRED_TRANSPORTS_ORDER) {
+            partitionInto(candidates, nai -> nai.getCapsNoCopy().hasTransport(transport),
+                    accepted, rejected);
+            if (accepted.size() == 1) return accepted.get(0);
+            if (accepted.size() > 0 && rejected.size() > 0) {
+                candidates = new ArrayList<>(accepted);
+                break;
+            }
+        }
+
+        // At this point there are still multiple networks passing all the tests above. If any
+        // of them is the previous satisfier, keep it.
+        if (candidates.contains(currentSatisfier)) return currentSatisfier;
+
+        // If there are still multiple options at this point but none of them is any of the
+        // transports above, it doesn't matter which is returned. They are all the same.
+        return candidates.get(0);
+    }
+
+    // TODO : switch to the policy implementation and remove
+    // Almost equivalent to Collections.max(nais), but allows returning null if no network
+    // satisfies the request.
+    private NetworkAgentInfo getBestNetworkByLegacyInt(
+            @NonNull final Collection<NetworkAgentInfo> nais) {
+        NetworkAgentInfo bestNetwork = null;
+        int bestScore = Integer.MIN_VALUE;
+        for (final NetworkAgentInfo nai : nais) {
+            final int naiScore = nai.getCurrentScore();
+            if (naiScore > bestScore) {
+                bestNetwork = nai;
+                bestScore = naiScore;
+            }
+        }
+        return bestNetwork;
+    }
+
+    /**
+     * Returns whether a {@link Scoreable} has a chance to beat a champion network for a request.
+     *
+     * Offers are sent by network providers when they think they might be able to make a network
+     * with the characteristics contained in the offer. If the offer has no chance to beat
+     * the currently best network for a given request, there is no point in the provider spending
+     * power trying to find and bring up such a network.
+     *
+     * Note that having an offer up does not constitute a commitment from the provider part
+     * to be able to bring up a network with these characteristics, or a network at all for
+     * that matter. This is only used to save power by letting providers know when they can't
+     * beat a current champion.
+     *
+     * @param request The request to evaluate against.
+     * @param champion The currently best network for this request.
+     * @param contestant The offer.
+     * @return Whether the offer stands a chance to beat the champion.
+     */
+    public boolean mightBeat(@NonNull final NetworkRequest request,
+            @Nullable final NetworkAgentInfo champion,
+            @NonNull final Scoreable contestant) {
+        // If this network can't even satisfy the request then it can't beat anything, not
+        // even an absence of network. It can't satisfy it anyway.
+        if (!request.canBeSatisfiedBy(contestant.getCapsNoCopy())) return false;
+        // If there is no satisfying network, then this network can beat, because some network
+        // is always better than no network.
+        if (null == champion) return true;
+        if (USE_POLICY_RANKING) {
+            // If there is no champion, the offer can always beat.
+            // Otherwise rank them.
+            final ArrayList<Scoreable> candidates = new ArrayList<>();
+            candidates.add(champion);
+            candidates.add(contestant);
+            return contestant == getBestNetworkByPolicy(candidates, champion);
+        } else {
+            return mightBeatByLegacyInt(champion.getScore(), contestant);
+        }
+    }
+
+    /**
+     * Returns whether a contestant might beat a champion according to the legacy int.
+     */
+    private boolean mightBeatByLegacyInt(@Nullable final FullScore championScore,
+            @NonNull final Scoreable contestant) {
+        final int offerIntScore;
+        if (contestant.getCapsNoCopy().hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)) {
+            // If the offer might have Internet access, then it might validate.
+            offerIntScore = contestant.getScore().getLegacyIntAsValidated();
+        } else {
+            offerIntScore = contestant.getScore().getLegacyInt();
+        }
+        return championScore.getLegacyInt() < offerIntScore;
+    }
+}
diff --git a/service/src/com/android/server/connectivity/OsCompat.java b/service/src/com/android/server/connectivity/OsCompat.java
new file mode 100644
index 0000000..57e3dcd
--- /dev/null
+++ b/service/src/com/android/server/connectivity/OsCompat.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import android.system.ErrnoException;
+import android.system.Os;
+
+import java.io.FileDescriptor;
+
+/**
+ * Compatibility utility for android.system.Os core platform APIs.
+ *
+ * Connectivity has access to such APIs, but they are not part of the module_current stubs yet
+ * (only core_current). Most stable core platform APIs are included manually in the connectivity
+ * build rules, but because Os is also part of the base java SDK that is earlier on the
+ * classpath, the extra core platform APIs are not seen.
+ *
+ * TODO (b/157639992, b/183097033): remove as soon as core_current is part of system_server_current
+ * @hide
+ */
+public class OsCompat {
+    // This value should be correct on all architectures supported by Android, but hardcoding ioctl
+    // numbers should be avoided.
+    /**
+     * @see android.system.OsConstants#TIOCOUTQ
+     */
+    public static final int TIOCOUTQ = 0x5411;
+
+    /**
+     * @see android.system.Os#getsockoptInt(FileDescriptor, int, int)
+     */
+    public static int getsockoptInt(FileDescriptor fd, int level, int option) throws
+            ErrnoException {
+        try {
+            return (int) Os.class.getMethod(
+                    "getsockoptInt", FileDescriptor.class, int.class, int.class)
+                    .invoke(null, fd, level, option);
+        } catch (ReflectiveOperationException e) {
+            if (e.getCause() instanceof ErrnoException) {
+                throw (ErrnoException) e.getCause();
+            }
+            throw new IllegalStateException("Error calling getsockoptInt", e);
+        }
+    }
+
+    /**
+     * @see android.system.Os#ioctlInt(FileDescriptor, int)
+     */
+    public static int ioctlInt(FileDescriptor fd, int cmd) throws
+            ErrnoException {
+        try {
+            return (int) Os.class.getMethod(
+                    "ioctlInt", FileDescriptor.class, int.class).invoke(null, fd, cmd);
+        } catch (ReflectiveOperationException e) {
+            if (e.getCause() instanceof ErrnoException) {
+                throw (ErrnoException) e.getCause();
+            }
+            throw new IllegalStateException("Error calling ioctlInt", e);
+        }
+    }
+}
diff --git a/service/src/com/android/server/connectivity/PermissionMonitor.java b/service/src/com/android/server/connectivity/PermissionMonitor.java
new file mode 100644
index 0000000..5886b1a
--- /dev/null
+++ b/service/src/com/android/server/connectivity/PermissionMonitor.java
@@ -0,0 +1,733 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.Manifest.permission.CHANGE_NETWORK_STATE;
+import static android.Manifest.permission.CONNECTIVITY_USE_RESTRICTED_NETWORKS;
+import static android.Manifest.permission.INTERNET;
+import static android.Manifest.permission.NETWORK_STACK;
+import static android.Manifest.permission.UPDATE_DEVICE_STATS;
+import static android.content.pm.PackageInfo.REQUESTED_PERMISSION_GRANTED;
+import static android.content.pm.PackageManager.GET_PERMISSIONS;
+import static android.content.pm.PackageManager.MATCH_ANY_USER;
+import static android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK;
+import static android.os.Process.INVALID_UID;
+import static android.os.Process.SYSTEM_UID;
+
+import static com.android.net.module.util.CollectionUtils.toIntArray;
+
+import android.annotation.NonNull;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.NameNotFoundException;
+import android.net.INetd;
+import android.net.UidRange;
+import android.net.Uri;
+import android.os.Build;
+import android.os.RemoteException;
+import android.os.ServiceSpecificException;
+import android.os.SystemConfigManager;
+import android.os.UserHandle;
+import android.os.UserManager;
+import android.system.OsConstants;
+import android.util.Log;
+import android.util.SparseArray;
+import android.util.SparseIntArray;
+
+import com.android.internal.annotations.GuardedBy;
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.util.IndentingPrintWriter;
+import com.android.net.module.util.CollectionUtils;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+
+
+/**
+ * A utility class to inform Netd of UID permisisons.
+ * Does a mass update at boot and then monitors for app install/remove.
+ *
+ * @hide
+ */
+public class PermissionMonitor {
+    private static final String TAG = "PermissionMonitor";
+    private static final boolean DBG = true;
+    protected static final Boolean SYSTEM = Boolean.TRUE;
+    protected static final Boolean NETWORK = Boolean.FALSE;
+    private static final int VERSION_Q = Build.VERSION_CODES.Q;
+
+    private final PackageManager mPackageManager;
+    private final UserManager mUserManager;
+    private final SystemConfigManager mSystemConfigManager;
+    private final INetd mNetd;
+    private final Dependencies mDeps;
+    private final Context mContext;
+
+    @GuardedBy("this")
+    private final Set<UserHandle> mUsers = new HashSet<>();
+
+    // Keys are app uids. Values are true for SYSTEM permission and false for NETWORK permission.
+    @GuardedBy("this")
+    private final Map<Integer, Boolean> mApps = new HashMap<>();
+
+    // Keys are active non-bypassable and fully-routed VPN's interface name, Values are uid ranges
+    // for apps under the VPN
+    @GuardedBy("this")
+    private final Map<String, Set<UidRange>> mVpnUidRanges = new HashMap<>();
+
+    // A set of appIds for apps across all users on the device. We track appIds instead of uids
+    // directly to reduce its size and also eliminate the need to update this set when user is
+    // added/removed.
+    @GuardedBy("this")
+    private final Set<Integer> mAllApps = new HashSet<>();
+
+    private BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            final String action = intent.getAction();
+            final int uid = intent.getIntExtra(Intent.EXTRA_UID, -1);
+            final Uri packageData = intent.getData();
+            final String packageName =
+                    packageData != null ? packageData.getSchemeSpecificPart() : null;
+
+            if (Intent.ACTION_PACKAGE_ADDED.equals(action)) {
+                onPackageAdded(packageName, uid);
+            } else if (Intent.ACTION_PACKAGE_REMOVED.equals(action)) {
+                onPackageRemoved(packageName, uid);
+            } else {
+                Log.wtf(TAG, "received unexpected intent: " + action);
+            }
+        }
+    };
+
+    /**
+     * Dependencies of PermissionMonitor, for injection in tests.
+     */
+    @VisibleForTesting
+    public static class Dependencies {
+        /**
+         * Get device first sdk version.
+         */
+        public int getDeviceFirstSdkInt() {
+            return Build.VERSION.DEVICE_INITIAL_SDK_INT;
+        }
+    }
+
+    public PermissionMonitor(@NonNull final Context context, @NonNull final INetd netd) {
+        this(context, netd, new Dependencies());
+    }
+
+    @VisibleForTesting
+    PermissionMonitor(@NonNull final Context context, @NonNull final INetd netd,
+            @NonNull final Dependencies deps) {
+        mPackageManager = context.getPackageManager();
+        mUserManager = (UserManager) context.getSystemService(Context.USER_SERVICE);
+        mSystemConfigManager = context.getSystemService(SystemConfigManager.class);
+        mNetd = netd;
+        mDeps = deps;
+        mContext = context;
+    }
+
+    // Intended to be called only once at startup, after the system is ready. Installs a broadcast
+    // receiver to monitor ongoing UID changes, so this shouldn't/needn't be called again.
+    public synchronized void startMonitoring() {
+        log("Monitoring");
+
+        final IntentFilter intentFilter = new IntentFilter();
+        intentFilter.addAction(Intent.ACTION_PACKAGE_ADDED);
+        intentFilter.addAction(Intent.ACTION_PACKAGE_REMOVED);
+        intentFilter.addDataScheme("package");
+        mContext.createContextAsUser(UserHandle.ALL, 0 /* flags */).registerReceiver(
+                mIntentReceiver, intentFilter, null /* broadcastPermission */,
+                null /* scheduler */);
+
+        List<PackageInfo> apps = mPackageManager.getInstalledPackages(GET_PERMISSIONS
+                | MATCH_ANY_USER);
+        if (apps == null) {
+            loge("No apps");
+            return;
+        }
+
+        SparseIntArray netdPermsUids = new SparseIntArray();
+
+        for (PackageInfo app : apps) {
+            int uid = app.applicationInfo != null ? app.applicationInfo.uid : INVALID_UID;
+            if (uid < 0) {
+                continue;
+            }
+            mAllApps.add(UserHandle.getAppId(uid));
+
+            boolean isNetwork = hasNetworkPermission(app);
+            boolean hasRestrictedPermission = hasRestrictedNetworkPermission(app);
+
+            if (isNetwork || hasRestrictedPermission) {
+                Boolean permission = mApps.get(uid);
+                // If multiple packages share a UID (cf: android:sharedUserId) and ask for different
+                // permissions, don't downgrade (i.e., if it's already SYSTEM, leave it as is).
+                if (permission == null || permission == NETWORK) {
+                    mApps.put(uid, hasRestrictedPermission);
+                }
+            }
+
+            //TODO: unify the management of the permissions into one codepath.
+            int otherNetdPerms = getNetdPermissionMask(app.requestedPermissions,
+                    app.requestedPermissionsFlags);
+            netdPermsUids.put(uid, netdPermsUids.get(uid) | otherNetdPerms);
+        }
+
+        mUsers.addAll(mUserManager.getUserHandles(true /* excludeDying */));
+
+        final SparseArray<String> netdPermToSystemPerm = new SparseArray<>();
+        netdPermToSystemPerm.put(INetd.PERMISSION_INTERNET, INTERNET);
+        netdPermToSystemPerm.put(INetd.PERMISSION_UPDATE_DEVICE_STATS, UPDATE_DEVICE_STATS);
+        for (int i = 0; i < netdPermToSystemPerm.size(); i++) {
+            final int netdPermission = netdPermToSystemPerm.keyAt(i);
+            final String systemPermission = netdPermToSystemPerm.valueAt(i);
+            final int[] hasPermissionUids =
+                    mSystemConfigManager.getSystemPermissionUids(systemPermission);
+            for (int j = 0; j < hasPermissionUids.length; j++) {
+                final int uid = hasPermissionUids[j];
+                netdPermsUids.put(uid, netdPermsUids.get(uid) | netdPermission);
+            }
+        }
+        log("Users: " + mUsers.size() + ", Apps: " + mApps.size());
+        update(mUsers, mApps, true);
+        sendPackagePermissionsToNetd(netdPermsUids);
+    }
+
+    @VisibleForTesting
+    static boolean isVendorApp(@NonNull ApplicationInfo appInfo) {
+        return appInfo.isVendor() || appInfo.isOem() || appInfo.isProduct();
+    }
+
+    @VisibleForTesting
+    boolean hasPermission(@NonNull final PackageInfo app, @NonNull final String permission) {
+        if (app.requestedPermissions == null || app.requestedPermissionsFlags == null) {
+            return false;
+        }
+        final int index = CollectionUtils.indexOf(app.requestedPermissions, permission);
+        if (index < 0 || index >= app.requestedPermissionsFlags.length) return false;
+        return (app.requestedPermissionsFlags[index] & REQUESTED_PERMISSION_GRANTED) != 0;
+    }
+
+    @VisibleForTesting
+    boolean hasNetworkPermission(@NonNull final PackageInfo app) {
+        return hasPermission(app, CHANGE_NETWORK_STATE);
+    }
+
+    @VisibleForTesting
+    boolean hasRestrictedNetworkPermission(@NonNull final PackageInfo app) {
+        // TODO : remove this check in the future(b/31479477). All apps should just
+        // request the appropriate permission for their use case since android Q.
+        if (app.applicationInfo != null) {
+            // Backward compatibility for b/114245686, on devices that launched before Q daemons
+            // and apps running as the system UID are exempted from this check.
+            if (app.applicationInfo.uid == SYSTEM_UID && mDeps.getDeviceFirstSdkInt() < VERSION_Q) {
+                return true;
+            }
+
+            if (app.applicationInfo.targetSdkVersion < VERSION_Q
+                    && isVendorApp(app.applicationInfo)) {
+                return true;
+            }
+        }
+
+        return hasPermission(app, PERMISSION_MAINLINE_NETWORK_STACK)
+                || hasPermission(app, NETWORK_STACK)
+                || hasPermission(app, CONNECTIVITY_USE_RESTRICTED_NETWORKS);
+    }
+
+    /** Returns whether the given uid has using background network permission. */
+    public synchronized boolean hasUseBackgroundNetworksPermission(final int uid) {
+        // Apps with any of the CHANGE_NETWORK_STATE, NETWORK_STACK, CONNECTIVITY_INTERNAL or
+        // CONNECTIVITY_USE_RESTRICTED_NETWORKS permission has the permission to use background
+        // networks. mApps contains the result of checks for both hasNetworkPermission and
+        // hasRestrictedNetworkPermission. If uid is in the mApps list that means uid has one of
+        // permissions at least.
+        return mApps.containsKey(uid);
+    }
+
+    /**
+     * Returns whether the given uid has permission to use restricted networks.
+     */
+    public synchronized boolean hasRestrictedNetworksPermission(int uid) {
+        return Boolean.TRUE.equals(mApps.get(uid));
+    }
+
+    private void update(Set<UserHandle> users, Map<Integer, Boolean> apps, boolean add) {
+        List<Integer> network = new ArrayList<>();
+        List<Integer> system = new ArrayList<>();
+        for (Entry<Integer, Boolean> app : apps.entrySet()) {
+            List<Integer> list = app.getValue() ? system : network;
+            for (UserHandle user : users) {
+                if (user == null) continue;
+
+                list.add(user.getUid(app.getKey()));
+            }
+        }
+        try {
+            if (add) {
+                mNetd.networkSetPermissionForUser(INetd.PERMISSION_NETWORK, toIntArray(network));
+                mNetd.networkSetPermissionForUser(INetd.PERMISSION_SYSTEM, toIntArray(system));
+            } else {
+                mNetd.networkClearPermissionForUser(toIntArray(network));
+                mNetd.networkClearPermissionForUser(toIntArray(system));
+            }
+        } catch (RemoteException e) {
+            loge("Exception when updating permissions: " + e);
+        }
+    }
+
+    /**
+     * Called when a user is added. See {link #ACTION_USER_ADDED}.
+     *
+     * @param user The integer userHandle of the added user. See {@link #EXTRA_USER_HANDLE}.
+     *
+     * @hide
+     */
+    public synchronized void onUserAdded(@NonNull UserHandle user) {
+        mUsers.add(user);
+
+        Set<UserHandle> users = new HashSet<>();
+        users.add(user);
+        update(users, mApps, true);
+    }
+
+    /**
+     * Called when an user is removed. See {link #ACTION_USER_REMOVED}.
+     *
+     * @param user The integer userHandle of the removed user. See {@link #EXTRA_USER_HANDLE}.
+     *
+     * @hide
+     */
+    public synchronized void onUserRemoved(@NonNull UserHandle user) {
+        mUsers.remove(user);
+
+        Set<UserHandle> users = new HashSet<>();
+        users.add(user);
+        update(users, mApps, false);
+    }
+
+    @VisibleForTesting
+    protected Boolean highestPermissionForUid(Boolean currentPermission, String name) {
+        if (currentPermission == SYSTEM) {
+            return currentPermission;
+        }
+        try {
+            final PackageInfo app = mPackageManager.getPackageInfo(name,
+                    GET_PERMISSIONS | MATCH_ANY_USER);
+            final boolean isNetwork = hasNetworkPermission(app);
+            final boolean hasRestrictedPermission = hasRestrictedNetworkPermission(app);
+            if (isNetwork || hasRestrictedPermission) {
+                currentPermission = hasRestrictedPermission;
+            }
+        } catch (NameNotFoundException e) {
+            // App not found.
+            loge("NameNotFoundException " + name);
+        }
+        return currentPermission;
+    }
+
+    private int getPermissionForUid(final int uid) {
+        int permission = INetd.PERMISSION_NONE;
+        // Check all the packages for this UID. The UID has the permission if any of the
+        // packages in it has the permission.
+        final String[] packages = mPackageManager.getPackagesForUid(uid);
+        if (packages != null && packages.length > 0) {
+            for (String name : packages) {
+                final PackageInfo app = getPackageInfo(name);
+                if (app != null && app.requestedPermissions != null) {
+                    permission |= getNetdPermissionMask(app.requestedPermissions,
+                            app.requestedPermissionsFlags);
+                }
+            }
+        } else {
+            // The last package of this uid is removed from device. Clean the package up.
+            permission = INetd.PERMISSION_UNINSTALLED;
+        }
+        return permission;
+    }
+
+    /**
+     * Called when a package is added.
+     *
+     * @param packageName The name of the new package.
+     * @param uid The uid of the new package.
+     *
+     * @hide
+     */
+    public synchronized void onPackageAdded(@NonNull final String packageName, final int uid) {
+        // TODO: Netd is using appId for checking traffic permission. Correct the methods that are
+        //  using appId instead of uid actually
+        sendPackagePermissionsForUid(UserHandle.getAppId(uid), getPermissionForUid(uid));
+
+        // If multiple packages share a UID (cf: android:sharedUserId) and ask for different
+        // permissions, don't downgrade (i.e., if it's already SYSTEM, leave it as is).
+        final Boolean permission = highestPermissionForUid(mApps.get(uid), packageName);
+        if (permission != mApps.get(uid)) {
+            mApps.put(uid, permission);
+
+            Map<Integer, Boolean> apps = new HashMap<>();
+            apps.put(uid, permission);
+            update(mUsers, apps, true);
+        }
+
+        // If the newly-installed package falls within some VPN's uid range, update Netd with it.
+        // This needs to happen after the mApps update above, since removeBypassingUids() depends
+        // on mApps to check if the package can bypass VPN.
+        for (Map.Entry<String, Set<UidRange>> vpn : mVpnUidRanges.entrySet()) {
+            if (UidRange.containsUid(vpn.getValue(), uid)) {
+                final Set<Integer> changedUids = new HashSet<>();
+                changedUids.add(uid);
+                removeBypassingUids(changedUids, /* vpnAppUid */ -1);
+                updateVpnUids(vpn.getKey(), changedUids, true);
+            }
+        }
+        mAllApps.add(UserHandle.getAppId(uid));
+    }
+
+    /**
+     * Called when a package is removed.
+     *
+     * @param packageName The name of the removed package or null.
+     * @param uid containing the integer uid previously assigned to the package.
+     *
+     * @hide
+     */
+    public synchronized void onPackageRemoved(@NonNull final String packageName, final int uid) {
+        // TODO: Netd is using appId for checking traffic permission. Correct the methods that are
+        //  using appId instead of uid actually
+        sendPackagePermissionsForUid(UserHandle.getAppId(uid), getPermissionForUid(uid));
+
+        // If the newly-removed package falls within some VPN's uid range, update Netd with it.
+        // This needs to happen before the mApps update below, since removeBypassingUids() depends
+        // on mApps to check if the package can bypass VPN.
+        for (Map.Entry<String, Set<UidRange>> vpn : mVpnUidRanges.entrySet()) {
+            if (UidRange.containsUid(vpn.getValue(), uid)) {
+                final Set<Integer> changedUids = new HashSet<>();
+                changedUids.add(uid);
+                removeBypassingUids(changedUids, /* vpnAppUid */ -1);
+                updateVpnUids(vpn.getKey(), changedUids, false);
+            }
+        }
+        // If the package has been removed from all users on the device, clear it form mAllApps.
+        if (mPackageManager.getNameForUid(uid) == null) {
+            mAllApps.remove(UserHandle.getAppId(uid));
+        }
+
+        Map<Integer, Boolean> apps = new HashMap<>();
+        Boolean permission = null;
+        String[] packages = mPackageManager.getPackagesForUid(uid);
+        if (packages != null && packages.length > 0) {
+            for (String name : packages) {
+                permission = highestPermissionForUid(permission, name);
+                if (permission == SYSTEM) {
+                    // An app with this UID still has the SYSTEM permission.
+                    // Therefore, this UID must already have the SYSTEM permission.
+                    // Nothing to do.
+                    return;
+                }
+            }
+        }
+        if (permission == mApps.get(uid)) {
+            // The permissions of this UID have not changed. Nothing to do.
+            return;
+        } else if (permission != null) {
+            mApps.put(uid, permission);
+            apps.put(uid, permission);
+            update(mUsers, apps, true);
+        } else {
+            mApps.remove(uid);
+            apps.put(uid, NETWORK);  // doesn't matter which permission we pick here
+            update(mUsers, apps, false);
+        }
+    }
+
+    private static int getNetdPermissionMask(String[] requestedPermissions,
+                                             int[] requestedPermissionsFlags) {
+        int permissions = 0;
+        if (requestedPermissions == null || requestedPermissionsFlags == null) return permissions;
+        for (int i = 0; i < requestedPermissions.length; i++) {
+            if (requestedPermissions[i].equals(INTERNET)
+                    && ((requestedPermissionsFlags[i] & REQUESTED_PERMISSION_GRANTED) != 0)) {
+                permissions |= INetd.PERMISSION_INTERNET;
+            }
+            if (requestedPermissions[i].equals(UPDATE_DEVICE_STATS)
+                    && ((requestedPermissionsFlags[i] & REQUESTED_PERMISSION_GRANTED) != 0)) {
+                permissions |= INetd.PERMISSION_UPDATE_DEVICE_STATS;
+            }
+        }
+        return permissions;
+    }
+
+    private PackageInfo getPackageInfo(String packageName) {
+        try {
+            PackageInfo app = mPackageManager.getPackageInfo(packageName, GET_PERMISSIONS
+                    | MATCH_ANY_USER);
+            return app;
+        } catch (NameNotFoundException e) {
+            return null;
+        }
+    }
+
+    /**
+     * Called when a new set of UID ranges are added to an active VPN network
+     *
+     * @param iface The active VPN network's interface name
+     * @param rangesToAdd The new UID ranges to be added to the network
+     * @param vpnAppUid The uid of the VPN app
+     */
+    public synchronized void onVpnUidRangesAdded(@NonNull String iface, Set<UidRange> rangesToAdd,
+            int vpnAppUid) {
+        // Calculate the list of new app uids under the VPN due to the new UID ranges and update
+        // Netd about them. Because mAllApps only contains appIds instead of uids, the result might
+        // be an overestimation if an app is not installed on the user on which the VPN is running,
+        // but that's safe.
+        final Set<Integer> changedUids = intersectUids(rangesToAdd, mAllApps);
+        removeBypassingUids(changedUids, vpnAppUid);
+        updateVpnUids(iface, changedUids, true);
+        if (mVpnUidRanges.containsKey(iface)) {
+            mVpnUidRanges.get(iface).addAll(rangesToAdd);
+        } else {
+            mVpnUidRanges.put(iface, new HashSet<UidRange>(rangesToAdd));
+        }
+    }
+
+    /**
+     * Called when a set of UID ranges are removed from an active VPN network
+     *
+     * @param iface The VPN network's interface name
+     * @param rangesToRemove Existing UID ranges to be removed from the VPN network
+     * @param vpnAppUid The uid of the VPN app
+     */
+    public synchronized void onVpnUidRangesRemoved(@NonNull String iface,
+            Set<UidRange> rangesToRemove, int vpnAppUid) {
+        // Calculate the list of app uids that are no longer under the VPN due to the removed UID
+        // ranges and update Netd about them.
+        final Set<Integer> changedUids = intersectUids(rangesToRemove, mAllApps);
+        removeBypassingUids(changedUids, vpnAppUid);
+        updateVpnUids(iface, changedUids, false);
+        Set<UidRange> existingRanges = mVpnUidRanges.getOrDefault(iface, null);
+        if (existingRanges == null) {
+            loge("Attempt to remove unknown vpn uid Range iface = " + iface);
+            return;
+        }
+        existingRanges.removeAll(rangesToRemove);
+        if (existingRanges.size() == 0) {
+            mVpnUidRanges.remove(iface);
+        }
+    }
+
+    /**
+     * Compute the intersection of a set of UidRanges and appIds. Returns a set of uids
+     * that satisfies:
+     *   1. falls into one of the UidRange
+     *   2. matches one of the appIds
+     */
+    private Set<Integer> intersectUids(Set<UidRange> ranges, Set<Integer> appIds) {
+        Set<Integer> result = new HashSet<>();
+        for (UidRange range : ranges) {
+            for (int userId = range.getStartUser(); userId <= range.getEndUser(); userId++) {
+                for (int appId : appIds) {
+                    final UserHandle handle = UserHandle.of(userId);
+                    if (handle == null) continue;
+
+                    final int uid = handle.getUid(appId);
+                    if (range.contains(uid)) {
+                        result.add(uid);
+                    }
+                }
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Remove all apps which can elect to bypass the VPN from the list of uids
+     *
+     * An app can elect to bypass the VPN if it hold SYSTEM permission, or if its the active VPN
+     * app itself.
+     *
+     * @param uids The list of uids to operate on
+     * @param vpnAppUid The uid of the VPN app
+     */
+    private void removeBypassingUids(Set<Integer> uids, int vpnAppUid) {
+        uids.remove(vpnAppUid);
+        uids.removeIf(uid -> mApps.getOrDefault(uid, NETWORK) == SYSTEM);
+    }
+
+    /**
+     * Update netd about the list of uids that are under an active VPN connection which they cannot
+     * bypass.
+     *
+     * This is to instruct netd to set up appropriate filtering rules for these uids, such that they
+     * can only receive ingress packets from the VPN's tunnel interface (and loopback).
+     *
+     * @param iface the interface name of the active VPN connection
+     * @param add {@code true} if the uids are to be added to the interface, {@code false} if they
+     *        are to be removed from the interface.
+     */
+    private void updateVpnUids(String iface, Set<Integer> uids, boolean add) {
+        if (uids.size() == 0) {
+            return;
+        }
+        try {
+            if (add) {
+                mNetd.firewallAddUidInterfaceRules(iface, toIntArray(uids));
+            } else {
+                mNetd.firewallRemoveUidInterfaceRules(toIntArray(uids));
+            }
+        } catch (ServiceSpecificException e) {
+            // Silently ignore exception when device does not support eBPF, otherwise just log
+            // the exception and do not crash
+            if (e.errorCode != OsConstants.EOPNOTSUPP) {
+                loge("Exception when updating permissions: ", e);
+            }
+        } catch (RemoteException e) {
+            loge("Exception when updating permissions: ", e);
+        }
+    }
+
+    /**
+     * Called by PackageListObserver when a package is installed/uninstalled. Send the updated
+     * permission information to netd.
+     *
+     * @param uid the app uid of the package installed
+     * @param permissions the permissions the app requested and netd cares about.
+     *
+     * @hide
+     */
+    @VisibleForTesting
+    void sendPackagePermissionsForUid(int uid, int permissions) {
+        SparseIntArray netdPermissionsAppIds = new SparseIntArray();
+        netdPermissionsAppIds.put(uid, permissions);
+        sendPackagePermissionsToNetd(netdPermissionsAppIds);
+    }
+
+    /**
+     * Called by packageManagerService to send IPC to netd. Grant or revoke the INTERNET
+     * and/or UPDATE_DEVICE_STATS permission of the uids in array.
+     *
+     * @param netdPermissionsAppIds integer pairs of uids and the permission granted to it. If the
+     * permission is 0, revoke all permissions of that uid.
+     *
+     * @hide
+     */
+    @VisibleForTesting
+    void sendPackagePermissionsToNetd(SparseIntArray netdPermissionsAppIds) {
+        if (mNetd == null) {
+            Log.e(TAG, "Failed to get the netd service");
+            return;
+        }
+        ArrayList<Integer> allPermissionAppIds = new ArrayList<>();
+        ArrayList<Integer> internetPermissionAppIds = new ArrayList<>();
+        ArrayList<Integer> updateStatsPermissionAppIds = new ArrayList<>();
+        ArrayList<Integer> noPermissionAppIds = new ArrayList<>();
+        ArrayList<Integer> uninstalledAppIds = new ArrayList<>();
+        for (int i = 0; i < netdPermissionsAppIds.size(); i++) {
+            int permissions = netdPermissionsAppIds.valueAt(i);
+            switch(permissions) {
+                case (INetd.PERMISSION_INTERNET | INetd.PERMISSION_UPDATE_DEVICE_STATS):
+                    allPermissionAppIds.add(netdPermissionsAppIds.keyAt(i));
+                    break;
+                case INetd.PERMISSION_INTERNET:
+                    internetPermissionAppIds.add(netdPermissionsAppIds.keyAt(i));
+                    break;
+                case INetd.PERMISSION_UPDATE_DEVICE_STATS:
+                    updateStatsPermissionAppIds.add(netdPermissionsAppIds.keyAt(i));
+                    break;
+                case INetd.PERMISSION_NONE:
+                    noPermissionAppIds.add(netdPermissionsAppIds.keyAt(i));
+                    break;
+                case INetd.PERMISSION_UNINSTALLED:
+                    uninstalledAppIds.add(netdPermissionsAppIds.keyAt(i));
+                    break;
+                default:
+                    Log.e(TAG, "unknown permission type: " + permissions + "for uid: "
+                            + netdPermissionsAppIds.keyAt(i));
+            }
+        }
+        try {
+            // TODO: add a lock inside netd to protect IPC trafficSetNetPermForUids()
+            if (allPermissionAppIds.size() != 0) {
+                mNetd.trafficSetNetPermForUids(
+                        INetd.PERMISSION_INTERNET | INetd.PERMISSION_UPDATE_DEVICE_STATS,
+                        toIntArray(allPermissionAppIds));
+            }
+            if (internetPermissionAppIds.size() != 0) {
+                mNetd.trafficSetNetPermForUids(INetd.PERMISSION_INTERNET,
+                        toIntArray(internetPermissionAppIds));
+            }
+            if (updateStatsPermissionAppIds.size() != 0) {
+                mNetd.trafficSetNetPermForUids(INetd.PERMISSION_UPDATE_DEVICE_STATS,
+                        toIntArray(updateStatsPermissionAppIds));
+            }
+            if (noPermissionAppIds.size() != 0) {
+                mNetd.trafficSetNetPermForUids(INetd.PERMISSION_NONE,
+                        toIntArray(noPermissionAppIds));
+            }
+            if (uninstalledAppIds.size() != 0) {
+                mNetd.trafficSetNetPermForUids(INetd.PERMISSION_UNINSTALLED,
+                        toIntArray(uninstalledAppIds));
+            }
+        } catch (RemoteException e) {
+            Log.e(TAG, "Pass appId list of special permission failed." + e);
+        }
+    }
+
+    /** Should only be used by unit tests */
+    @VisibleForTesting
+    public Set<UidRange> getVpnUidRanges(String iface) {
+        return mVpnUidRanges.get(iface);
+    }
+
+    /** Dump info to dumpsys */
+    public void dump(IndentingPrintWriter pw) {
+        pw.println("Interface filtering rules:");
+        pw.increaseIndent();
+        for (Map.Entry<String, Set<UidRange>> vpn : mVpnUidRanges.entrySet()) {
+            pw.println("Interface: " + vpn.getKey());
+            pw.println("UIDs: " + vpn.getValue().toString());
+            pw.println();
+        }
+        pw.decreaseIndent();
+    }
+
+    private static void log(String s) {
+        if (DBG) {
+            Log.d(TAG, s);
+        }
+    }
+
+    private static void loge(String s) {
+        Log.e(TAG, s);
+    }
+
+    private static void loge(String s, Throwable e) {
+        Log.e(TAG, s, e);
+    }
+}
diff --git a/service/src/com/android/server/connectivity/ProfileNetworkPreferences.java b/service/src/com/android/server/connectivity/ProfileNetworkPreferences.java
new file mode 100644
index 0000000..dd2815d
--- /dev/null
+++ b/service/src/com/android/server/connectivity/ProfileNetworkPreferences.java
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.net.NetworkCapabilities;
+import android.os.UserHandle;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * A data class containing all the per-profile network preferences.
+ *
+ * A given profile can only have one preference.
+ */
+public class ProfileNetworkPreferences {
+    /**
+     * A single preference, as it applies to a given user profile.
+     */
+    public static class Preference {
+        @NonNull public final UserHandle user;
+        // Capabilities are only null when sending an object to remove the setting for a user
+        @Nullable public final NetworkCapabilities capabilities;
+
+        public Preference(@NonNull final UserHandle user,
+                @Nullable final NetworkCapabilities capabilities) {
+            this.user = user;
+            this.capabilities = null == capabilities ? null : new NetworkCapabilities(capabilities);
+        }
+
+        /** toString */
+        public String toString() {
+            return "[ProfileNetworkPreference user=" + user + " caps=" + capabilities + "]";
+        }
+    }
+
+    @NonNull public final List<Preference> preferences;
+
+    public ProfileNetworkPreferences() {
+        preferences = Collections.EMPTY_LIST;
+    }
+
+    private ProfileNetworkPreferences(@NonNull final List<Preference> list) {
+        preferences = Collections.unmodifiableList(list);
+    }
+
+    /**
+     * Returns a new object consisting of this object plus the passed preference.
+     *
+     * If a preference already exists for the same user, it will be replaced by the passed
+     * preference. Passing a Preference object containing a null capabilities object is equivalent
+     * to (and indeed, implemented as) removing the preference for this user.
+     */
+    public ProfileNetworkPreferences plus(@NonNull final Preference pref) {
+        final ArrayList<Preference> newPrefs = new ArrayList<>();
+        for (final Preference existingPref : preferences) {
+            if (!existingPref.user.equals(pref.user)) {
+                newPrefs.add(existingPref);
+            }
+        }
+        if (null != pref.capabilities) {
+            newPrefs.add(pref);
+        }
+        return new ProfileNetworkPreferences(newPrefs);
+    }
+
+    public boolean isEmpty() {
+        return preferences.isEmpty();
+    }
+}
diff --git a/service/src/com/android/server/connectivity/ProxyTracker.java b/service/src/com/android/server/connectivity/ProxyTracker.java
new file mode 100644
index 0000000..bc0929c
--- /dev/null
+++ b/service/src/com/android/server/connectivity/ProxyTracker.java
@@ -0,0 +1,358 @@
+/**
+ * Copyright (c) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.net.ConnectivitySettingsManager.GLOBAL_HTTP_PROXY_EXCLUSION_LIST;
+import static android.net.ConnectivitySettingsManager.GLOBAL_HTTP_PROXY_HOST;
+import static android.net.ConnectivitySettingsManager.GLOBAL_HTTP_PROXY_PAC;
+import static android.net.ConnectivitySettingsManager.GLOBAL_HTTP_PROXY_PORT;
+import static android.provider.Settings.Global.HTTP_PROXY;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.content.ContentResolver;
+import android.content.Context;
+import android.content.Intent;
+import android.net.Network;
+import android.net.PacProxyManager;
+import android.net.Proxy;
+import android.net.ProxyInfo;
+import android.net.Uri;
+import android.os.Binder;
+import android.os.Handler;
+import android.os.UserHandle;
+import android.provider.Settings;
+import android.text.TextUtils;
+import android.util.Log;
+import android.util.Pair;
+
+import com.android.internal.annotations.GuardedBy;
+import com.android.net.module.util.ProxyUtils;
+
+import java.util.Collections;
+import java.util.Objects;
+
+/**
+ * A class to handle proxy for ConnectivityService.
+ *
+ * @hide
+ */
+public class ProxyTracker {
+    private static final String TAG = ProxyTracker.class.getSimpleName();
+    private static final boolean DBG = true;
+
+    // EXTRA_PROXY_INFO is now @removed. In order to continue sending it, hardcode its value here.
+    // The Proxy.EXTRA_PROXY_INFO constant is not visible to this code because android.net.Proxy
+    // a hidden platform constant not visible to mainline modules.
+    private static final String EXTRA_PROXY_INFO = "android.intent.extra.PROXY_INFO";
+
+    @NonNull
+    private final Context mContext;
+
+    @NonNull
+    private final Object mProxyLock = new Object();
+    // The global proxy is the proxy that is set device-wide, overriding any network-specific
+    // proxy. Note however that proxies are hints ; the system does not enforce their use. Hence
+    // this value is only for querying.
+    @Nullable
+    @GuardedBy("mProxyLock")
+    private ProxyInfo mGlobalProxy = null;
+    // The default proxy is the proxy that applies to no particular network if the global proxy
+    // is not set. Individual networks have their own settings that override this. This member
+    // is set through setDefaultProxy, which is called when the default network changes proxies
+    // in its LinkProperties, or when ConnectivityService switches to a new default network, or
+    // when PacProxyService resolves the proxy.
+    @Nullable
+    @GuardedBy("mProxyLock")
+    private volatile ProxyInfo mDefaultProxy = null;
+    // Whether the default proxy is enabled.
+    @GuardedBy("mProxyLock")
+    private boolean mDefaultProxyEnabled = true;
+
+    private final Handler mConnectivityServiceHandler;
+
+    private final PacProxyManager mPacProxyManager;
+
+    private class PacProxyInstalledListener implements PacProxyManager.PacProxyInstalledListener {
+        private final int mEvent;
+
+        PacProxyInstalledListener(int event) {
+            mEvent = event;
+        }
+
+        public void onPacProxyInstalled(@Nullable Network network, @NonNull ProxyInfo proxy) {
+            mConnectivityServiceHandler
+                    .sendMessage(mConnectivityServiceHandler
+                    .obtainMessage(mEvent, new Pair<>(network, proxy)));
+        }
+    }
+
+    public ProxyTracker(@NonNull final Context context,
+            @NonNull final Handler connectivityServiceInternalHandler, final int pacChangedEvent) {
+        mContext = context;
+        mConnectivityServiceHandler = connectivityServiceInternalHandler;
+        mPacProxyManager = context.getSystemService(PacProxyManager.class);
+
+        PacProxyInstalledListener listener = new PacProxyInstalledListener(pacChangedEvent);
+        mPacProxyManager.addPacProxyInstalledListener(
+                mConnectivityServiceHandler::post, listener);
+    }
+
+    // Convert empty ProxyInfo's to null as null-checks are used to determine if proxies are present
+    // (e.g. if mGlobalProxy==null fall back to network-specific proxy, if network-specific
+    // proxy is null then there is no proxy in place).
+    @Nullable
+    private static ProxyInfo canonicalizeProxyInfo(@Nullable final ProxyInfo proxy) {
+        if (proxy != null && TextUtils.isEmpty(proxy.getHost())
+                && Uri.EMPTY.equals(proxy.getPacFileUrl())) {
+            return null;
+        }
+        return proxy;
+    }
+
+    // ProxyInfo equality functions with a couple modifications over ProxyInfo.equals() to make it
+    // better for determining if a new proxy broadcast is necessary:
+    // 1. Canonicalize empty ProxyInfos to null so an empty proxy compares equal to null so as to
+    //    avoid unnecessary broadcasts.
+    // 2. Make sure all parts of the ProxyInfo's compare true, including the host when a PAC URL
+    //    is in place.  This is important so legacy PAC resolver (see com.android.proxyhandler)
+    //    changes aren't missed.  The legacy PAC resolver pretends to be a simple HTTP proxy but
+    //    actually uses the PAC to resolve; this results in ProxyInfo's with PAC URL, host and port
+    //    all set.
+    public static boolean proxyInfoEqual(@Nullable final ProxyInfo a, @Nullable final ProxyInfo b) {
+        final ProxyInfo pa = canonicalizeProxyInfo(a);
+        final ProxyInfo pb = canonicalizeProxyInfo(b);
+        // ProxyInfo.equals() doesn't check hosts when PAC URLs are present, but we need to check
+        // hosts even when PAC URLs are present to account for the legacy PAC resolver.
+        return Objects.equals(pa, pb) && (pa == null || Objects.equals(pa.getHost(), pb.getHost()));
+    }
+
+    /**
+     * Gets the default system-wide proxy.
+     *
+     * This will return the global proxy if set, otherwise the default proxy if in use. Note
+     * that this is not necessarily the proxy that any given process should use, as the right
+     * proxy for a process is the proxy for the network this process will use, which may be
+     * different from this value. This value is simply the default in case there is no proxy set
+     * in the network that will be used by a specific process.
+     * @return The default system-wide proxy or null if none.
+     */
+    @Nullable
+    public ProxyInfo getDefaultProxy() {
+        // This information is already available as a world read/writable jvm property.
+        synchronized (mProxyLock) {
+            if (mGlobalProxy != null) return mGlobalProxy;
+            if (mDefaultProxyEnabled) return mDefaultProxy;
+            return null;
+        }
+    }
+
+    /**
+     * Gets the global proxy.
+     *
+     * @return The global proxy or null if none.
+     */
+    @Nullable
+    public ProxyInfo getGlobalProxy() {
+        // This information is already available as a world read/writable jvm property.
+        synchronized (mProxyLock) {
+            return mGlobalProxy;
+        }
+    }
+
+    /**
+     * Read the global proxy settings and cache them in memory.
+     */
+    public void loadGlobalProxy() {
+        if (loadDeprecatedGlobalHttpProxy()) {
+            return;
+        }
+        ContentResolver res = mContext.getContentResolver();
+        String host = Settings.Global.getString(res, GLOBAL_HTTP_PROXY_HOST);
+        int port = Settings.Global.getInt(res, GLOBAL_HTTP_PROXY_PORT, 0);
+        String exclList = Settings.Global.getString(res, GLOBAL_HTTP_PROXY_EXCLUSION_LIST);
+        String pacFileUrl = Settings.Global.getString(res, GLOBAL_HTTP_PROXY_PAC);
+        if (!TextUtils.isEmpty(host) || !TextUtils.isEmpty(pacFileUrl)) {
+            ProxyInfo proxyProperties;
+            if (!TextUtils.isEmpty(pacFileUrl)) {
+                proxyProperties = ProxyInfo.buildPacProxy(Uri.parse(pacFileUrl));
+            } else {
+                proxyProperties = ProxyInfo.buildDirectProxy(host, port,
+                        ProxyUtils.exclusionStringAsList(exclList));
+            }
+            if (!proxyProperties.isValid()) {
+                if (DBG) Log.d(TAG, "Invalid proxy properties, ignoring: " + proxyProperties);
+                return;
+            }
+
+            synchronized (mProxyLock) {
+                mGlobalProxy = proxyProperties;
+            }
+
+            if (!TextUtils.isEmpty(pacFileUrl)) {
+                mConnectivityServiceHandler.post(
+                        () -> mPacProxyManager.setCurrentProxyScriptUrl(proxyProperties));
+            }
+        }
+    }
+
+    /**
+     * Read the global proxy from the deprecated Settings.Global.HTTP_PROXY setting and apply it.
+     * Returns {@code true} when global proxy was set successfully from deprecated setting.
+     */
+    public boolean loadDeprecatedGlobalHttpProxy() {
+        final String proxy = Settings.Global.getString(mContext.getContentResolver(), HTTP_PROXY);
+        if (!TextUtils.isEmpty(proxy)) {
+            String data[] = proxy.split(":");
+            if (data.length == 0) {
+                return false;
+            }
+
+            final String proxyHost = data[0];
+            int proxyPort = 8080;
+            if (data.length > 1) {
+                try {
+                    proxyPort = Integer.parseInt(data[1]);
+                } catch (NumberFormatException e) {
+                    return false;
+                }
+            }
+            final ProxyInfo p = ProxyInfo.buildDirectProxy(proxyHost, proxyPort,
+                    Collections.emptyList());
+            setGlobalProxy(p);
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Sends the system broadcast informing apps about a new proxy configuration.
+     *
+     * Confusingly this method also sets the PAC file URL. TODO : separate this, it has nothing
+     * to do in a "sendProxyBroadcast" method.
+     */
+    public void sendProxyBroadcast() {
+        final ProxyInfo defaultProxy = getDefaultProxy();
+        final ProxyInfo proxyInfo = null != defaultProxy ?
+                defaultProxy : ProxyInfo.buildDirectProxy("", 0, Collections.emptyList());
+        mPacProxyManager.setCurrentProxyScriptUrl(proxyInfo);
+
+        if (!shouldSendBroadcast(proxyInfo)) {
+            return;
+        }
+        if (DBG) Log.d(TAG, "sending Proxy Broadcast for " + proxyInfo);
+        Intent intent = new Intent(Proxy.PROXY_CHANGE_ACTION);
+        intent.addFlags(Intent.FLAG_RECEIVER_REPLACE_PENDING |
+                Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);
+        intent.putExtra(EXTRA_PROXY_INFO, proxyInfo);
+        final long ident = Binder.clearCallingIdentity();
+        try {
+            mContext.sendStickyBroadcastAsUser(intent, UserHandle.ALL);
+        } finally {
+            Binder.restoreCallingIdentity(ident);
+        }
+    }
+
+    private boolean shouldSendBroadcast(ProxyInfo proxy) {
+        return Uri.EMPTY.equals(proxy.getPacFileUrl()) || proxy.getPort() > 0;
+    }
+
+    /**
+     * Sets the global proxy in memory. Also writes the values to the global settings of the device.
+     *
+     * @param proxyInfo the proxy spec, or null for no proxy.
+     */
+    public void setGlobalProxy(@Nullable ProxyInfo proxyInfo) {
+        synchronized (mProxyLock) {
+            // ProxyInfo#equals is not commutative :( and is public API, so it can't be fixed.
+            if (proxyInfo == mGlobalProxy) return;
+            if (proxyInfo != null && proxyInfo.equals(mGlobalProxy)) return;
+            if (mGlobalProxy != null && mGlobalProxy.equals(proxyInfo)) return;
+
+            final String host;
+            final int port;
+            final String exclList;
+            final String pacFileUrl;
+            if (proxyInfo != null && (!TextUtils.isEmpty(proxyInfo.getHost()) ||
+                    !Uri.EMPTY.equals(proxyInfo.getPacFileUrl()))) {
+                if (!proxyInfo.isValid()) {
+                    if (DBG) Log.d(TAG, "Invalid proxy properties, ignoring: " + proxyInfo);
+                    return;
+                }
+                mGlobalProxy = new ProxyInfo(proxyInfo);
+                host = mGlobalProxy.getHost();
+                port = mGlobalProxy.getPort();
+                exclList = ProxyUtils.exclusionListAsString(mGlobalProxy.getExclusionList());
+                pacFileUrl = Uri.EMPTY.equals(proxyInfo.getPacFileUrl())
+                        ? "" : proxyInfo.getPacFileUrl().toString();
+            } else {
+                host = "";
+                port = 0;
+                exclList = "";
+                pacFileUrl = "";
+                mGlobalProxy = null;
+            }
+            final ContentResolver res = mContext.getContentResolver();
+            final long token = Binder.clearCallingIdentity();
+            try {
+                Settings.Global.putString(res, GLOBAL_HTTP_PROXY_HOST, host);
+                Settings.Global.putInt(res, GLOBAL_HTTP_PROXY_PORT, port);
+                Settings.Global.putString(res, GLOBAL_HTTP_PROXY_EXCLUSION_LIST, exclList);
+                Settings.Global.putString(res, GLOBAL_HTTP_PROXY_PAC, pacFileUrl);
+            } finally {
+                Binder.restoreCallingIdentity(token);
+            }
+
+            sendProxyBroadcast();
+        }
+    }
+
+    /**
+     * Sets the default proxy for the device.
+     *
+     * The default proxy is the proxy used for networks that do not have a specific proxy.
+     * @param proxyInfo the proxy spec, or null for no proxy.
+     */
+    public void setDefaultProxy(@Nullable ProxyInfo proxyInfo) {
+        synchronized (mProxyLock) {
+            if (Objects.equals(mDefaultProxy, proxyInfo)) return;
+            if (proxyInfo != null &&  !proxyInfo.isValid()) {
+                if (DBG) Log.d(TAG, "Invalid proxy properties, ignoring: " + proxyInfo);
+                return;
+            }
+
+            // This call could be coming from the PacProxyService, containing the port of the
+            // local proxy. If this new proxy matches the global proxy then copy this proxy to the
+            // global (to get the correct local port), and send a broadcast.
+            // TODO: Switch PacProxyService to have its own message to send back rather than
+            // reusing EVENT_HAS_CHANGED_PROXY and this call to handleApplyDefaultProxy.
+            if ((mGlobalProxy != null) && (proxyInfo != null)
+                    && (!Uri.EMPTY.equals(proxyInfo.getPacFileUrl()))
+                    && proxyInfo.getPacFileUrl().equals(mGlobalProxy.getPacFileUrl())) {
+                mGlobalProxy = proxyInfo;
+                sendProxyBroadcast();
+                return;
+            }
+            mDefaultProxy = proxyInfo;
+
+            if (mGlobalProxy != null) return;
+            if (mDefaultProxyEnabled) {
+                sendProxyBroadcast();
+            }
+        }
+    }
+}
diff --git a/service/src/com/android/server/connectivity/QosCallbackAgentConnection.java b/service/src/com/android/server/connectivity/QosCallbackAgentConnection.java
new file mode 100644
index 0000000..534dbe7
--- /dev/null
+++ b/service/src/com/android/server/connectivity/QosCallbackAgentConnection.java
@@ -0,0 +1,199 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import static android.net.QosCallbackException.EX_TYPE_FILTER_NONE;
+
+import android.annotation.NonNull;
+import android.net.IQosCallback;
+import android.net.Network;
+import android.net.QosCallbackException;
+import android.net.QosFilter;
+import android.net.QosSession;
+import android.os.IBinder;
+import android.os.RemoteException;
+import android.telephony.data.EpsBearerQosSessionAttributes;
+import android.telephony.data.NrQosSessionAttributes;
+import android.util.Log;
+
+import java.util.Objects;
+
+/**
+ * Wraps callback related information and sends messages between network agent and the application.
+ * <p/>
+ * This is a satellite class of {@link com.android.server.ConnectivityService} and not meant
+ * to be used in other contexts.
+ *
+ * @hide
+ */
+class QosCallbackAgentConnection implements IBinder.DeathRecipient {
+    private static final String TAG = QosCallbackAgentConnection.class.getSimpleName();
+    private static final boolean DBG = false;
+
+    private final int mAgentCallbackId;
+    @NonNull private final QosCallbackTracker mQosCallbackTracker;
+    @NonNull private final IQosCallback mCallback;
+    @NonNull private final IBinder mBinder;
+    @NonNull private final QosFilter mFilter;
+    @NonNull private final NetworkAgentInfo mNetworkAgentInfo;
+
+    private final int mUid;
+
+    /**
+     * Gets the uid
+     * @return uid
+     */
+    int getUid() {
+        return mUid;
+    }
+
+    /**
+     * Gets the binder
+     * @return binder
+     */
+    @NonNull
+    IBinder getBinder() {
+        return mBinder;
+    }
+
+    /**
+     * Gets the callback id
+     *
+     * @return callback id
+     */
+    int getAgentCallbackId() {
+        return mAgentCallbackId;
+    }
+
+    /**
+     * Gets the network tied to the callback of this connection
+     *
+     * @return network
+     */
+    @NonNull
+    Network getNetwork() {
+        return mFilter.getNetwork();
+    }
+
+    QosCallbackAgentConnection(@NonNull final QosCallbackTracker qosCallbackTracker,
+            final int agentCallbackId,
+            @NonNull final IQosCallback callback,
+            @NonNull final QosFilter filter,
+            final int uid,
+            @NonNull final NetworkAgentInfo networkAgentInfo) {
+        Objects.requireNonNull(qosCallbackTracker, "qosCallbackTracker must be non-null");
+        Objects.requireNonNull(callback, "callback must be non-null");
+        Objects.requireNonNull(filter, "filter must be non-null");
+        Objects.requireNonNull(networkAgentInfo, "networkAgentInfo must be non-null");
+
+        mQosCallbackTracker = qosCallbackTracker;
+        mAgentCallbackId = agentCallbackId;
+        mCallback = callback;
+        mFilter = filter;
+        mUid = uid;
+        mBinder = mCallback.asBinder();
+        mNetworkAgentInfo = networkAgentInfo;
+    }
+
+    @Override
+    public void binderDied() {
+        logw("binderDied: binder died with callback id: " + mAgentCallbackId);
+        mQosCallbackTracker.unregisterCallback(mCallback);
+    }
+
+    void unlinkToDeathRecipient() {
+        mBinder.unlinkToDeath(this, 0);
+    }
+
+    // Returns false if the NetworkAgent was never notified.
+    boolean sendCmdRegisterCallback() {
+        final int exceptionType = mFilter.validate();
+        if (exceptionType != EX_TYPE_FILTER_NONE) {
+            try {
+                if (DBG) log("sendCmdRegisterCallback: filter validation failed");
+                mCallback.onError(exceptionType);
+            } catch (final RemoteException e) {
+                loge("sendCmdRegisterCallback:", e);
+            }
+            return false;
+        }
+
+        try {
+            mBinder.linkToDeath(this, 0);
+        } catch (final RemoteException e) {
+            loge("failed linking to death recipient", e);
+            return false;
+        }
+        mNetworkAgentInfo.onQosFilterCallbackRegistered(mAgentCallbackId, mFilter);
+        return true;
+    }
+
+    void sendCmdUnregisterCallback() {
+        if (DBG) log("sendCmdUnregisterCallback: unregistering");
+        mNetworkAgentInfo.onQosCallbackUnregistered(mAgentCallbackId);
+    }
+
+    void sendEventEpsQosSessionAvailable(final QosSession session,
+            final EpsBearerQosSessionAttributes attributes) {
+        try {
+            if (DBG) log("sendEventEpsQosSessionAvailable: sending...");
+            mCallback.onQosEpsBearerSessionAvailable(session, attributes);
+        } catch (final RemoteException e) {
+            loge("sendEventEpsQosSessionAvailable: remote exception", e);
+        }
+    }
+
+    void sendEventNrQosSessionAvailable(final QosSession session,
+            final NrQosSessionAttributes attributes) {
+        try {
+            if (DBG) log("sendEventNrQosSessionAvailable: sending...");
+            mCallback.onNrQosSessionAvailable(session, attributes);
+        } catch (final RemoteException e) {
+            loge("sendEventNrQosSessionAvailable: remote exception", e);
+        }
+    }
+
+    void sendEventQosSessionLost(@NonNull final QosSession session) {
+        try {
+            if (DBG) log("sendEventQosSessionLost: sending...");
+            mCallback.onQosSessionLost(session);
+        } catch (final RemoteException e) {
+            loge("sendEventQosSessionLost: remote exception", e);
+        }
+    }
+
+    void sendEventQosCallbackError(@QosCallbackException.ExceptionType final int exceptionType) {
+        try {
+            if (DBG) log("sendEventQosCallbackError: sending...");
+            mCallback.onError(exceptionType);
+        } catch (final RemoteException e) {
+            loge("sendEventQosCallbackError: remote exception", e);
+        }
+    }
+
+    private static void log(@NonNull final String msg) {
+        Log.d(TAG, msg);
+    }
+
+    private static void logw(@NonNull final String msg) {
+        Log.w(TAG, msg);
+    }
+
+    private static void loge(@NonNull final String msg, final Throwable t) {
+        Log.e(TAG, msg, t);
+    }
+}
diff --git a/service/src/com/android/server/connectivity/QosCallbackTracker.java b/service/src/com/android/server/connectivity/QosCallbackTracker.java
new file mode 100644
index 0000000..b6ab47b
--- /dev/null
+++ b/service/src/com/android/server/connectivity/QosCallbackTracker.java
@@ -0,0 +1,292 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.connectivity;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.net.IQosCallback;
+import android.net.Network;
+import android.net.QosCallbackException;
+import android.net.QosFilter;
+import android.net.QosSession;
+import android.os.Binder;
+import android.os.Handler;
+import android.os.IBinder;
+import android.telephony.data.EpsBearerQosSessionAttributes;
+import android.telephony.data.NrQosSessionAttributes;
+import android.util.Log;
+
+import com.android.net.module.util.CollectionUtils;
+import com.android.server.ConnectivityService;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Tracks qos callbacks and handles the communication between the network agent and application.
+ * <p/>
+ * Any method prefixed by handle must be called from the
+ * {@link com.android.server.ConnectivityService} handler thread.
+ *
+ * @hide
+ */
+public class QosCallbackTracker {
+    private static final String TAG = QosCallbackTracker.class.getSimpleName();
+    private static final boolean DBG = true;
+
+    @NonNull
+    private final Handler mConnectivityServiceHandler;
+
+    @NonNull
+    private final ConnectivityService.PerUidCounter mNetworkRequestCounter;
+
+    /**
+     * Each agent gets a unique callback id that is used to proxy messages back to the original
+     * callback.
+     * <p/>
+     * Note: The fact that this is initialized to 0 is to ensure that the thread running
+     * {@link #handleRegisterCallback(IQosCallback, QosFilter, int, NetworkAgentInfo)} sees the
+     * initialized value. This would not necessarily be the case if the value was initialized to
+     * the non-default value.
+     * <p/>
+     * Note: The term previous does not apply to the first callback id that is assigned.
+     */
+    private int mPreviousAgentCallbackId = 0;
+
+    @NonNull
+    private final List<QosCallbackAgentConnection> mConnections = new ArrayList<>();
+
+    /**
+     *
+     * @param connectivityServiceHandler must be the same handler used with
+     *                {@link com.android.server.ConnectivityService}
+     * @param networkRequestCounter keeps track of the number of open requests under a given
+     *                              uid
+     */
+    public QosCallbackTracker(@NonNull final Handler connectivityServiceHandler,
+            final ConnectivityService.PerUidCounter networkRequestCounter) {
+        mConnectivityServiceHandler = connectivityServiceHandler;
+        mNetworkRequestCounter = networkRequestCounter;
+    }
+
+    /**
+     * Registers the callback with the tracker
+     *
+     * @param callback the callback to register
+     * @param filter the filter being registered alongside the callback
+     */
+    public void registerCallback(@NonNull final IQosCallback callback,
+            @NonNull final QosFilter filter, @NonNull final NetworkAgentInfo networkAgentInfo) {
+        final int uid = Binder.getCallingUid();
+
+        // Enforce that the number of requests under this uid has exceeded the allowed number
+        mNetworkRequestCounter.incrementCountOrThrow(uid);
+
+        mConnectivityServiceHandler.post(
+                () -> handleRegisterCallback(callback, filter, uid, networkAgentInfo));
+    }
+
+    private void handleRegisterCallback(@NonNull final IQosCallback callback,
+            @NonNull final QosFilter filter, final int uid,
+            @NonNull final NetworkAgentInfo networkAgentInfo) {
+        final QosCallbackAgentConnection ac =
+                handleRegisterCallbackInternal(callback, filter, uid, networkAgentInfo);
+        if (ac != null) {
+            if (DBG) log("handleRegisterCallback: added callback " + ac.getAgentCallbackId());
+            mConnections.add(ac);
+        } else {
+            mNetworkRequestCounter.decrementCount(uid);
+        }
+    }
+
+    private QosCallbackAgentConnection handleRegisterCallbackInternal(
+            @NonNull final IQosCallback callback,
+            @NonNull final QosFilter filter, final int uid,
+            @NonNull final NetworkAgentInfo networkAgentInfo) {
+        final IBinder binder = callback.asBinder();
+        if (CollectionUtils.any(mConnections, c -> c.getBinder().equals(binder))) {
+            // A duplicate registration would have only made this far due to a programming error.
+            logwtf("handleRegisterCallback: Callbacks can only be register once.");
+            return null;
+        }
+
+        mPreviousAgentCallbackId = mPreviousAgentCallbackId + 1;
+        final int newCallbackId = mPreviousAgentCallbackId;
+
+        final QosCallbackAgentConnection ac =
+                new QosCallbackAgentConnection(this, newCallbackId, callback,
+                        filter, uid, networkAgentInfo);
+
+        final int exceptionType = filter.validate();
+        if (exceptionType != QosCallbackException.EX_TYPE_FILTER_NONE) {
+            ac.sendEventQosCallbackError(exceptionType);
+            return null;
+        }
+
+        // Only add to the callback maps if the NetworkAgent successfully registered it
+        if (!ac.sendCmdRegisterCallback()) {
+            // There was an issue when registering the agent
+            if (DBG) log("handleRegisterCallback: error sending register callback");
+            mNetworkRequestCounter.decrementCount(uid);
+            return null;
+        }
+        return ac;
+    }
+
+    /**
+     * Unregisters callback
+     * @param callback callback to unregister
+     */
+    public void unregisterCallback(@NonNull final IQosCallback callback) {
+        mConnectivityServiceHandler.post(() -> handleUnregisterCallback(callback.asBinder(), true));
+    }
+
+    private void handleUnregisterCallback(@NonNull final IBinder binder,
+            final boolean sendToNetworkAgent) {
+        final int connIndex =
+                CollectionUtils.indexOf(mConnections, c -> c.getBinder().equals(binder));
+        if (connIndex < 0) {
+            logw("handleUnregisterCallback: no matching agentConnection");
+            return;
+        }
+        final QosCallbackAgentConnection agentConnection = mConnections.get(connIndex);
+
+        if (DBG) {
+            log("handleUnregisterCallback: unregister "
+                    + agentConnection.getAgentCallbackId());
+        }
+
+        mNetworkRequestCounter.decrementCount(agentConnection.getUid());
+        mConnections.remove(agentConnection);
+
+        if (sendToNetworkAgent) {
+            agentConnection.sendCmdUnregisterCallback();
+        }
+        agentConnection.unlinkToDeathRecipient();
+    }
+
+    /**
+     * Called when the NetworkAgent sends the qos session available event for EPS
+     *
+     * @param qosCallbackId the callback id that the qos session is now available to
+     * @param session the qos session that is now available
+     * @param attributes the qos attributes that are now available on the qos session
+     */
+    public void sendEventEpsQosSessionAvailable(final int qosCallbackId,
+            final QosSession session,
+            final EpsBearerQosSessionAttributes attributes) {
+        runOnAgentConnection(qosCallbackId, "sendEventEpsQosSessionAvailable: ",
+                ac -> ac.sendEventEpsQosSessionAvailable(session, attributes));
+    }
+
+    /**
+     * Called when the NetworkAgent sends the qos session available event for NR
+     *
+     * @param qosCallbackId the callback id that the qos session is now available to
+     * @param session the qos session that is now available
+     * @param attributes the qos attributes that are now available on the qos session
+     */
+    public void sendEventNrQosSessionAvailable(final int qosCallbackId,
+            final QosSession session,
+            final NrQosSessionAttributes attributes) {
+        runOnAgentConnection(qosCallbackId, "sendEventNrQosSessionAvailable: ",
+                ac -> ac.sendEventNrQosSessionAvailable(session, attributes));
+    }
+
+    /**
+     * Called when the NetworkAgent sends the qos session lost event
+     *
+     * @param qosCallbackId the callback id that lost the qos session
+     * @param session the corresponding qos session
+     */
+    public void sendEventQosSessionLost(final int qosCallbackId,
+            final QosSession session) {
+        runOnAgentConnection(qosCallbackId, "sendEventQosSessionLost: ",
+                ac -> ac.sendEventQosSessionLost(session));
+    }
+
+    /**
+     * Called when the NetworkAgent sends the qos session on error event
+     *
+     * @param qosCallbackId the callback id that should receive the exception
+     * @param exceptionType the type of exception that caused the callback to error
+     */
+    public void sendEventQosCallbackError(final int qosCallbackId,
+            @QosCallbackException.ExceptionType final int exceptionType) {
+        runOnAgentConnection(qosCallbackId, "sendEventQosCallbackError: ",
+                ac -> {
+                    ac.sendEventQosCallbackError(exceptionType);
+                    handleUnregisterCallback(ac.getBinder(), false);
+                });
+    }
+
+    /**
+     * Unregisters all callbacks associated to this network agent
+     *
+     * Note: Must be called on the connectivity service handler thread
+     *
+     * @param network the network that was released
+     */
+    public void handleNetworkReleased(@Nullable final Network network) {
+        // Iterate in reverse order as agent connections will be removed when unregistering
+        for (int i = mConnections.size() - 1; i >= 0; i--) {
+            final QosCallbackAgentConnection agentConnection = mConnections.get(i);
+            if (!agentConnection.getNetwork().equals(network)) continue;
+            agentConnection.sendEventQosCallbackError(
+                    QosCallbackException.EX_TYPE_FILTER_NETWORK_RELEASED);
+
+            // Call unregister workflow w\o sending anything to agent since it is disconnected.
+            handleUnregisterCallback(agentConnection.getBinder(), false);
+        }
+    }
+
+    private interface AgentConnectionAction {
+        void execute(@NonNull QosCallbackAgentConnection agentConnection);
+    }
+
+    @Nullable
+    private void runOnAgentConnection(final int qosCallbackId,
+            @NonNull final String logPrefix,
+            @NonNull final AgentConnectionAction action) {
+        mConnectivityServiceHandler.post(() -> {
+            final int acIndex = CollectionUtils.indexOf(mConnections,
+                            c -> c.getAgentCallbackId() == qosCallbackId);
+            if (acIndex == -1) {
+                loge(logPrefix + ": " + qosCallbackId + " missing callback id");
+                return;
+            }
+
+            action.execute(mConnections.get(acIndex));
+        });
+    }
+
+    private static void log(final String msg) {
+        Log.d(TAG, msg);
+    }
+
+    private static void logw(final String msg) {
+        Log.w(TAG, msg);
+    }
+
+    private static void loge(final String msg) {
+        Log.e(TAG, msg);
+    }
+
+    private static void logwtf(final String msg) {
+        Log.wtf(TAG, msg);
+    }
+}
diff --git a/service/src/com/android/server/connectivity/TcpKeepaliveController.java b/service/src/com/android/server/connectivity/TcpKeepaliveController.java
new file mode 100644
index 0000000..73f3475
--- /dev/null
+++ b/service/src/com/android/server/connectivity/TcpKeepaliveController.java
@@ -0,0 +1,340 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.server.connectivity;
+
+import static android.net.SocketKeepalive.DATA_RECEIVED;
+import static android.net.SocketKeepalive.ERROR_INVALID_SOCKET;
+import static android.net.SocketKeepalive.ERROR_SOCKET_NOT_IDLE;
+import static android.net.SocketKeepalive.ERROR_UNSUPPORTED;
+import static android.os.MessageQueue.OnFileDescriptorEventListener.EVENT_ERROR;
+import static android.os.MessageQueue.OnFileDescriptorEventListener.EVENT_INPUT;
+import static android.system.OsConstants.ENOPROTOOPT;
+import static android.system.OsConstants.FIONREAD;
+import static android.system.OsConstants.IPPROTO_IP;
+import static android.system.OsConstants.IPPROTO_TCP;
+import static android.system.OsConstants.IP_TOS;
+import static android.system.OsConstants.IP_TTL;
+
+import static com.android.server.connectivity.OsCompat.TIOCOUTQ;
+
+import android.annotation.NonNull;
+import android.net.InvalidPacketException;
+import android.net.NetworkUtils;
+import android.net.SocketKeepalive.InvalidSocketException;
+import android.net.TcpKeepalivePacketData;
+import android.net.TcpKeepalivePacketDataParcelable;
+import android.net.TcpRepairWindow;
+import android.net.util.KeepalivePacketDataUtil;
+import android.os.Handler;
+import android.os.MessageQueue;
+import android.os.Messenger;
+import android.system.ErrnoException;
+import android.system.Os;
+import android.util.Log;
+import android.util.SparseArray;
+
+import com.android.internal.annotations.GuardedBy;
+import com.android.server.connectivity.KeepaliveTracker.KeepaliveInfo;
+
+import java.io.FileDescriptor;
+import java.net.InetSocketAddress;
+import java.net.SocketAddress;
+import java.net.SocketException;
+
+/**
+ * Manage tcp socket which offloads tcp keepalive.
+ *
+ * The input socket will be changed to repair mode and the application
+ * will not have permission to read/write data. If the application wants
+ * to write data, it must stop tcp keepalive offload to leave repair mode
+ * first. If a remote packet arrives, repair mode will be turned off and
+ * offload will be stopped. The application will receive a callback to know
+ * it can start reading data.
+ *
+ * {start,stop}SocketMonitor are thread-safe, but care must be taken in the
+ * order in which they are called. Please note that while calling
+ * {@link #startSocketMonitor(FileDescriptor, Messenger, int)} multiple times
+ * with either the same slot or the same FileDescriptor without stopping it in
+ * between will result in an exception, calling {@link #stopSocketMonitor(int)}
+ * multiple times with the same int is explicitly a no-op.
+ * Please also note that switching the socket to repair mode is not synchronized
+ * with either of these operations and has to be done in an orderly fashion
+ * with stopSocketMonitor. Take care in calling these in the right order.
+ * @hide
+ */
+public class TcpKeepaliveController {
+    private static final String TAG = "TcpKeepaliveController";
+    private static final boolean DBG = false;
+
+    private final MessageQueue mFdHandlerQueue;
+
+    private static final int FD_EVENTS = EVENT_INPUT | EVENT_ERROR;
+
+    // Reference include/uapi/linux/tcp.h
+    private static final int TCP_REPAIR = 19;
+    private static final int TCP_REPAIR_QUEUE = 20;
+    private static final int TCP_QUEUE_SEQ = 21;
+    private static final int TCP_NO_QUEUE = 0;
+    private static final int TCP_RECV_QUEUE = 1;
+    private static final int TCP_SEND_QUEUE = 2;
+    private static final int TCP_REPAIR_OFF = 0;
+    private static final int TCP_REPAIR_ON = 1;
+    // Reference include/uapi/linux/sockios.h
+    private static final int SIOCINQ = FIONREAD;
+    private static final int SIOCOUTQ = TIOCOUTQ;
+
+    /**
+     * Keeps track of packet listeners.
+     * Key: slot number of keepalive offload.
+     * Value: {@link FileDescriptor} being listened to.
+     */
+    @GuardedBy("mListeners")
+    private final SparseArray<FileDescriptor> mListeners = new SparseArray<>();
+
+    public TcpKeepaliveController(final Handler connectivityServiceHandler) {
+        mFdHandlerQueue = connectivityServiceHandler.getLooper().getQueue();
+    }
+
+    /** Build tcp keepalive packet. */
+    public static TcpKeepalivePacketData getTcpKeepalivePacket(@NonNull FileDescriptor fd)
+            throws InvalidPacketException, InvalidSocketException {
+        try {
+            final TcpKeepalivePacketDataParcelable tcpDetails = switchToRepairMode(fd);
+            return KeepalivePacketDataUtil.fromStableParcelable(tcpDetails);
+        } catch (InvalidPacketException | InvalidSocketException e) {
+            switchOutOfRepairMode(fd);
+            throw e;
+        }
+    }
+    /**
+     * Switch the tcp socket to repair mode and query detail tcp information.
+     *
+     * @param fd the fd of socket on which to use keepalive offload.
+     * @return a {@link TcpKeepalivePacketDataParcelable} object for current
+     * tcp/ip information.
+     */
+    private static TcpKeepalivePacketDataParcelable switchToRepairMode(FileDescriptor fd)
+            throws InvalidSocketException {
+        if (DBG) Log.i(TAG, "switchToRepairMode to start tcp keepalive : " + fd);
+        final TcpKeepalivePacketDataParcelable tcpDetails = new TcpKeepalivePacketDataParcelable();
+        final SocketAddress srcSockAddr;
+        final SocketAddress dstSockAddr;
+        final TcpRepairWindow trw;
+
+        // Query source address and port.
+        try {
+            srcSockAddr = Os.getsockname(fd);
+        } catch (ErrnoException e) {
+            Log.e(TAG, "Get sockname fail: ", e);
+            throw new InvalidSocketException(ERROR_INVALID_SOCKET, e);
+        }
+        if (srcSockAddr instanceof InetSocketAddress) {
+            tcpDetails.srcAddress = getAddress((InetSocketAddress) srcSockAddr);
+            tcpDetails.srcPort = getPort((InetSocketAddress) srcSockAddr);
+        } else {
+            Log.e(TAG, "Invalid or mismatched SocketAddress");
+            throw new InvalidSocketException(ERROR_INVALID_SOCKET);
+        }
+        // Query destination address and port.
+        try {
+            dstSockAddr = Os.getpeername(fd);
+        } catch (ErrnoException e) {
+            Log.e(TAG, "Get peername fail: ", e);
+            throw new InvalidSocketException(ERROR_INVALID_SOCKET, e);
+        }
+        if (dstSockAddr instanceof InetSocketAddress) {
+            tcpDetails.dstAddress = getAddress((InetSocketAddress) dstSockAddr);
+            tcpDetails.dstPort = getPort((InetSocketAddress) dstSockAddr);
+        } else {
+            Log.e(TAG, "Invalid or mismatched peer SocketAddress");
+            throw new InvalidSocketException(ERROR_INVALID_SOCKET);
+        }
+
+        // Query sequence and ack number
+        dropAllIncomingPackets(fd, true);
+        try {
+            // Switch to tcp repair mode.
+            Os.setsockoptInt(fd, IPPROTO_TCP, TCP_REPAIR, TCP_REPAIR_ON);
+
+            // Check if socket is idle.
+            if (!isSocketIdle(fd)) {
+                Log.e(TAG, "Socket is not idle");
+                throw new InvalidSocketException(ERROR_SOCKET_NOT_IDLE);
+            }
+            // Query write sequence number from SEND_QUEUE.
+            Os.setsockoptInt(fd, IPPROTO_TCP, TCP_REPAIR_QUEUE, TCP_SEND_QUEUE);
+            tcpDetails.seq = OsCompat.getsockoptInt(fd, IPPROTO_TCP, TCP_QUEUE_SEQ);
+            // Query read sequence number from RECV_QUEUE.
+            Os.setsockoptInt(fd, IPPROTO_TCP, TCP_REPAIR_QUEUE, TCP_RECV_QUEUE);
+            tcpDetails.ack = OsCompat.getsockoptInt(fd, IPPROTO_TCP, TCP_QUEUE_SEQ);
+            // Switch to NO_QUEUE to prevent illegal socket read/write in repair mode.
+            Os.setsockoptInt(fd, IPPROTO_TCP, TCP_REPAIR_QUEUE, TCP_NO_QUEUE);
+            // Finally, check if socket is still idle. TODO : this check needs to move to
+            // after starting polling to prevent a race.
+            if (!isReceiveQueueEmpty(fd)) {
+                Log.e(TAG, "Fatal: receive queue of this socket is not empty");
+                throw new InvalidSocketException(ERROR_INVALID_SOCKET);
+            }
+            if (!isSendQueueEmpty(fd)) {
+                Log.e(TAG, "Socket is not idle");
+                throw new InvalidSocketException(ERROR_SOCKET_NOT_IDLE);
+            }
+
+            // Query tcp window size.
+            trw = NetworkUtils.getTcpRepairWindow(fd);
+            tcpDetails.rcvWnd = trw.rcvWnd;
+            tcpDetails.rcvWndScale = trw.rcvWndScale;
+            if (tcpDetails.srcAddress.length == 4 /* V4 address length */) {
+                // Query TOS.
+                tcpDetails.tos = OsCompat.getsockoptInt(fd, IPPROTO_IP, IP_TOS);
+                // Query TTL.
+                tcpDetails.ttl = OsCompat.getsockoptInt(fd, IPPROTO_IP, IP_TTL);
+            }
+        } catch (ErrnoException e) {
+            Log.e(TAG, "Exception reading TCP state from socket", e);
+            if (e.errno == ENOPROTOOPT) {
+                // ENOPROTOOPT may happen in kernel version lower than 4.8.
+                // Treat it as ERROR_UNSUPPORTED.
+                throw new InvalidSocketException(ERROR_UNSUPPORTED, e);
+            } else {
+                throw new InvalidSocketException(ERROR_INVALID_SOCKET, e);
+            }
+        } finally {
+            dropAllIncomingPackets(fd, false);
+        }
+
+        // Keepalive sequence number is last sequence number - 1. If it couldn't be retrieved,
+        // then it must be set to -1, so decrement in all cases.
+        tcpDetails.seq = tcpDetails.seq - 1;
+
+        return tcpDetails;
+    }
+
+    /**
+     * Switch the tcp socket out of repair mode.
+     *
+     * @param fd the fd of socket to switch back to normal.
+     */
+    private static void switchOutOfRepairMode(@NonNull final FileDescriptor fd) {
+        try {
+            Os.setsockoptInt(fd, IPPROTO_TCP, TCP_REPAIR, TCP_REPAIR_OFF);
+        } catch (ErrnoException e) {
+            Log.e(TAG, "Cannot switch socket out of repair mode", e);
+            // Well, there is not much to do here to recover
+        }
+    }
+
+    /**
+     * Start monitoring incoming packets.
+     *
+     * @param fd socket fd to monitor.
+     * @param ki a {@link KeepaliveInfo} that tracks information about a socket keepalive.
+     * @param slot keepalive slot.
+     */
+    public void startSocketMonitor(@NonNull final FileDescriptor fd,
+            @NonNull final KeepaliveInfo ki, final int slot)
+            throws IllegalArgumentException, InvalidSocketException {
+        synchronized (mListeners) {
+            if (null != mListeners.get(slot)) {
+                throw new IllegalArgumentException("This slot is already taken");
+            }
+            for (int i = 0; i < mListeners.size(); ++i) {
+                if (fd.equals(mListeners.valueAt(i))) {
+                    Log.e(TAG, "This fd is already registered.");
+                    throw new InvalidSocketException(ERROR_INVALID_SOCKET);
+                }
+            }
+            mFdHandlerQueue.addOnFileDescriptorEventListener(fd, FD_EVENTS, (readyFd, events) -> {
+                // This can't be called twice because the queue guarantees that once the listener
+                // is unregistered it can't be called again, even for a message that arrived
+                // before it was unregistered.
+                final int reason;
+                if (0 != (events & EVENT_ERROR)) {
+                    reason = ERROR_INVALID_SOCKET;
+                } else {
+                    reason = DATA_RECEIVED;
+                }
+                ki.onFileDescriptorInitiatedStop(reason);
+                // The listener returns the new set of events to listen to. Because 0 means no
+                // event, the listener gets unregistered.
+                return 0;
+            });
+            mListeners.put(slot, fd);
+        }
+    }
+
+    /** Stop socket monitor */
+    // This slot may have been stopped automatically already because the socket received data,
+    // was closed on the other end or otherwise suffered some error. In this case, this function
+    // is a no-op.
+    public void stopSocketMonitor(final int slot) {
+        final FileDescriptor fd;
+        synchronized (mListeners) {
+            fd = mListeners.get(slot);
+            if (null == fd) return;
+            mListeners.remove(slot);
+        }
+        mFdHandlerQueue.removeOnFileDescriptorEventListener(fd);
+        if (DBG) Log.d(TAG, "Moving socket out of repair mode for stop : " + fd);
+        switchOutOfRepairMode(fd);
+    }
+
+    private static byte [] getAddress(InetSocketAddress inetAddr) {
+        return inetAddr.getAddress().getAddress();
+    }
+
+    private static int getPort(InetSocketAddress inetAddr) {
+        return inetAddr.getPort();
+    }
+
+    private static boolean isSocketIdle(FileDescriptor fd) throws ErrnoException {
+        return isReceiveQueueEmpty(fd) && isSendQueueEmpty(fd);
+    }
+
+    private static boolean isReceiveQueueEmpty(FileDescriptor fd)
+            throws ErrnoException {
+        final int result = OsCompat.ioctlInt(fd, SIOCINQ);
+        if (result != 0) {
+            Log.e(TAG, "Read queue has data");
+            return false;
+        }
+        return true;
+    }
+
+    private static boolean isSendQueueEmpty(FileDescriptor fd)
+            throws ErrnoException {
+        final int result = OsCompat.ioctlInt(fd, SIOCOUTQ);
+        if (result != 0) {
+            Log.e(TAG, "Write queue has data");
+            return false;
+        }
+        return true;
+    }
+
+    private static void dropAllIncomingPackets(FileDescriptor fd, boolean enable)
+            throws InvalidSocketException {
+        try {
+            if (enable) {
+                NetworkUtils.attachDropAllBPFFilter(fd);
+            } else {
+                NetworkUtils.detachBPFFilter(fd);
+            }
+        } catch (SocketException e) {
+            Log.e(TAG, "Socket Exception: ", e);
+            throw new InvalidSocketException(ERROR_INVALID_SOCKET, e);
+        }
+    }
+}