diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index a7e6a2e..87ac0a8 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -101,6 +101,7 @@
 import static com.android.net.module.util.PermissionUtils.enforceAnyPermissionOf;
 import static com.android.net.module.util.PermissionUtils.enforceNetworkStackPermission;
 import static com.android.net.module.util.PermissionUtils.enforceNetworkStackPermissionOr;
+import static com.android.server.connectivity.KeepaliveTracker.PERMISSION;
 
 import static java.util.Map.Entry;
 
@@ -269,6 +270,7 @@
 import com.android.networkstack.apishim.common.BroadcastOptionsShim;
 import com.android.networkstack.apishim.common.UnsupportedApiLevelException;
 import com.android.server.connectivity.AutodestructReference;
+import com.android.server.connectivity.AutomaticOnOffKeepaliveTracker;
 import com.android.server.connectivity.CarrierPrivilegeAuthenticator;
 import com.android.server.connectivity.ClatCoordinator;
 import com.android.server.connectivity.ConnectivityFlags;
@@ -276,7 +278,6 @@
 import com.android.server.connectivity.DnsManager.PrivateDnsValidationUpdate;
 import com.android.server.connectivity.DscpPolicyTracker;
 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.MultinetworkPolicyTracker;
@@ -843,7 +844,7 @@
 
     private final LocationPermissionChecker mLocationPermissionChecker;
 
-    private final KeepaliveTracker mKeepaliveTracker;
+    private final AutomaticOnOffKeepaliveTracker mKeepaliveTracker;
     private final QosCallbackTracker mQosCallbackTracker;
     private final NetworkNotificationManager mNotifier;
     private final LingerMonitor mLingerMonitor;
@@ -1565,7 +1566,7 @@
         mSettingsObserver = new SettingsObserver(mContext, mHandler);
         registerSettingsCallbacks();
 
-        mKeepaliveTracker = new KeepaliveTracker(mContext, mHandler);
+        mKeepaliveTracker = new AutomaticOnOffKeepaliveTracker(mContext, mHandler);
         mNotifier = new NetworkNotificationManager(mContext, mTelephonyManager);
         mQosCallbackTracker = new QosCallbackTracker(mHandler, mNetworkRequestCounter);
 
@@ -2998,7 +2999,7 @@
     }
 
     private void enforceKeepalivePermission() {
-        mContext.enforceCallingOrSelfPermission(KeepaliveTracker.PERMISSION, "ConnectivityService");
+        mContext.enforceCallingOrSelfPermission(PERMISSION, "ConnectivityService");
     }
 
     private boolean checkLocalMacAddressPermission(int pid, int uid) {
diff --git a/service/src/com/android/server/connectivity/AutomaticOnOffKeepaliveTracker.java b/service/src/com/android/server/connectivity/AutomaticOnOffKeepaliveTracker.java
new file mode 100644
index 0000000..85ec5e3
--- /dev/null
+++ b/service/src/com/android/server/connectivity/AutomaticOnOffKeepaliveTracker.java
@@ -0,0 +1,385 @@
+/*
+ * Copyright (C) 2023 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.AF_INET;
+import static android.system.OsConstants.AF_INET6;
+import static android.system.OsConstants.SOL_SOCKET;
+import static android.system.OsConstants.SO_SNDTIMEO;
+
+import static com.android.net.module.util.netlink.NetlinkConstants.NLMSG_DONE;
+import static com.android.net.module.util.netlink.NetlinkConstants.SOCKDIAG_MSG_HEADER_SIZE;
+import static com.android.net.module.util.netlink.NetlinkConstants.SOCK_DIAG_BY_FAMILY;
+import static com.android.net.module.util.netlink.NetlinkUtils.IO_TIMEOUT_MS;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.content.Context;
+import android.net.INetd;
+import android.net.ISocketKeepaliveCallback;
+import android.net.MarkMaskParcel;
+import android.os.Handler;
+import android.os.IBinder;
+import android.os.Message;
+import android.os.RemoteException;
+import android.system.ErrnoException;
+import android.system.Os;
+import android.system.StructTimeval;
+import android.util.Log;
+import android.util.SparseArray;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.util.IndentingPrintWriter;
+import com.android.net.module.util.HexDump;
+import com.android.net.module.util.SocketUtils;
+import com.android.net.module.util.netlink.InetDiagMessage;
+import com.android.net.module.util.netlink.NetlinkUtils;
+import com.android.net.module.util.netlink.StructNlAttr;
+
+import java.io.FileDescriptor;
+import java.io.InterruptedIOException;
+import java.net.SocketException;
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.util.Objects;
+
+/**
+ * Manages automatic on/off socket keepalive requests.
+ *
+ * Provides methods to stop and start automatic keepalive requests, and keeps track of keepalives
+ * across all networks. For non-automatic on/off keepalive request, this class bypass the requests
+ * and send to KeepaliveTrakcer. 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 AutomaticOnOffKeepaliveTracker {
+    private static final String TAG = "AutomaticOnOffKeepaliveTracker";
+    private static final int[] ADDRESS_FAMILIES = new int[] {AF_INET6, AF_INET};
+
+    @NonNull
+    private final Handler mConnectivityServiceHandler;
+    @NonNull
+    private final KeepaliveTracker mKeepaliveTracker;
+    @NonNull
+    private final Context mContext;
+
+    /**
+     * The {@code inetDiagReqV2} messages for different IP family.
+     *
+     *   Key: Ip family type.
+     * Value: Bytes array represent the {@code inetDiagReqV2}.
+     *
+     * This should only be accessed in the connectivity service handler thread.
+     */
+    private final SparseArray<byte[]> mSockDiagMsg = new SparseArray<>();
+    private final Dependencies mDependencies;
+    private final INetd mNetd;
+
+    public AutomaticOnOffKeepaliveTracker(Context context, Handler handler) {
+        this(context, handler, new Dependencies(context));
+    }
+
+    @VisibleForTesting
+    public AutomaticOnOffKeepaliveTracker(@NonNull Context context, @NonNull Handler handler,
+            @NonNull Dependencies dependencies) {
+        mContext = Objects.requireNonNull(context);
+        mDependencies = dependencies;
+        this.mConnectivityServiceHandler = Objects.requireNonNull(handler);
+        mNetd = mDependencies.getNetd();
+        mKeepaliveTracker = mDependencies.newKeepaliveTracker(
+                mContext, mConnectivityServiceHandler);
+    }
+
+    /**
+     * Handle keepalive events from lower layer.
+     */
+    public void handleEventSocketKeepalive(@NonNull NetworkAgentInfo nai, int slot, int reason) {
+        mKeepaliveTracker.handleEventSocketKeepalive(nai, slot, reason);
+    }
+
+    /**
+     * Handle stop all keepalives on the specific network.
+     */
+    public void handleStopAllKeepalives(NetworkAgentInfo nai, int reason) {
+        mKeepaliveTracker.handleStopAllKeepalives(nai, reason);
+    }
+
+    /**
+     *  Handle start keepalives with the message.
+     *
+     *  The message is expected to be a KeepaliveTracker.KeepaliveInfo.
+     */
+    public void handleStartKeepalive(Message message) {
+        mKeepaliveTracker.handleStartKeepalive(message);
+    }
+
+    /**
+     * Handle stop keepalives on the specific network with given slot.
+     */
+    public void handleStopKeepalive(NetworkAgentInfo nai, int slot, int reason) {
+        mKeepaliveTracker.handleStopKeepalive(nai, slot, reason);
+    }
+
+    /**
+     * 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) {
+        mKeepaliveTracker.startNattKeepalive(nai, fd, intervalSeconds, cb, srcAddrString,
+                srcPort, dstAddrString, dstPort);
+    }
+
+    /**
+     * 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 resourceId,
+            int intervalSeconds,
+            @NonNull ISocketKeepaliveCallback cb,
+            @NonNull String srcAddrString,
+            @NonNull String dstAddrString,
+            int dstPort) {
+        mKeepaliveTracker.startNattKeepalive(nai, fd, resourceId, intervalSeconds, cb,
+                srcAddrString, dstAddrString, dstPort);
+    }
+
+    /**
+     * 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) {
+        mKeepaliveTracker.startTcpKeepalive(nai, fd, intervalSeconds, cb);
+    }
+
+    /**
+     * Dump AutomaticOnOffKeepaliveTracker state.
+     */
+    public void dump(IndentingPrintWriter pw) {
+        // TODO:  Dump the necessary information for automatic on/off keepalive.
+        mKeepaliveTracker.dump(pw);
+    }
+
+    /**
+     * Check all keeplaives on the network are still valid.
+     */
+    public void handleCheckKeepalivesStillValid(NetworkAgentInfo nai) {
+        mKeepaliveTracker.handleCheckKeepalivesStillValid(nai);
+    }
+
+    @VisibleForTesting
+    boolean isAnyTcpSocketConnected(int netId) {
+        FileDescriptor fd = null;
+
+        try {
+            fd = mDependencies.createConnectedNetlinkSocket();
+
+            // Get network mask
+            final MarkMaskParcel parcel = mNetd.getFwmarkForNetwork(netId);
+            final int networkMark = (parcel != null) ? parcel.mark : NetlinkUtils.UNKNOWN_MARK;
+            final int networkMask = (parcel != null) ? parcel.mask : NetlinkUtils.NULL_MASK;
+
+            // Send request for each IP family
+            for (final int family : ADDRESS_FAMILIES) {
+                if (isAnyTcpSocketConnectedForFamily(fd, family, networkMark, networkMask)) {
+                    return true;
+                }
+            }
+        } catch (ErrnoException | SocketException | InterruptedIOException | RemoteException e) {
+            Log.e(TAG, "Fail to get socket info via netlink.", e);
+        } finally {
+            SocketUtils.closeSocketQuietly(fd);
+        }
+
+        return false;
+    }
+
+    private boolean isAnyTcpSocketConnectedForFamily(FileDescriptor fd, int family, int networkMark,
+            int networkMask) throws ErrnoException, InterruptedIOException {
+        ensureRunningOnHandlerThread();
+        // Build SocketDiag messages and cache it.
+        if (mSockDiagMsg.get(family) == null) {
+            mSockDiagMsg.put(family, InetDiagMessage.buildInetDiagReqForAliveTcpSockets(family));
+        }
+        mDependencies.sendRequest(fd, mSockDiagMsg.get(family));
+
+        // Iteration limitation as a protection to avoid possible infinite loops.
+        // DEFAULT_RECV_BUFSIZE could read more than 20 sockets per time. Max iteration
+        // should be enough to go through reasonable TCP sockets in the device.
+        final int maxIteration = 100;
+        int parsingIteration = 0;
+        while (parsingIteration < maxIteration) {
+            final ByteBuffer bytes = mDependencies.recvSockDiagResponse(fd);
+
+            try {
+                while (NetlinkUtils.enoughBytesRemainForValidNlMsg(bytes)) {
+                    final int startPos = bytes.position();
+
+                    final int nlmsgLen = bytes.getInt();
+                    final int nlmsgType = bytes.getShort();
+                    if (isEndOfMessageOrError(nlmsgType)) return false;
+                    // TODO: Parse InetDiagMessage to get uid and dst address information to filter
+                    //  socket via NetlinkMessage.parse.
+
+                    // Skip the header to move to data part.
+                    bytes.position(startPos + SOCKDIAG_MSG_HEADER_SIZE);
+
+                    if (isTargetTcpSocket(bytes, nlmsgLen, networkMark, networkMask)) {
+                        return true;
+                    }
+                }
+            } catch (BufferUnderflowException e) {
+                // The exception happens in random place in either header position or any data
+                // position. Partial bytes from the middle of the byte buffer may not be enough to
+                // clarify, so print out the content before the error to possibly prevent printing
+                // the whole 8K buffer.
+                final int exceptionPos = bytes.position();
+                final String hex = HexDump.dumpHexString(bytes.array(), 0, exceptionPos);
+                Log.e(TAG, "Unexpected socket info parsing: " + hex, e);
+            }
+
+            parsingIteration++;
+        }
+        return false;
+    }
+
+    private boolean isEndOfMessageOrError(int nlmsgType) {
+        return nlmsgType == NLMSG_DONE || nlmsgType != SOCK_DIAG_BY_FAMILY;
+    }
+
+    private boolean isTargetTcpSocket(@NonNull ByteBuffer bytes, int nlmsgLen, int networkMark,
+            int networkMask) {
+        final int mark = readSocketDataAndReturnMark(bytes, nlmsgLen);
+        return (mark & networkMask) == networkMark;
+    }
+
+    private int readSocketDataAndReturnMark(@NonNull ByteBuffer bytes, int nlmsgLen) {
+        final int nextMsgOffset = bytes.position() + nlmsgLen - SOCKDIAG_MSG_HEADER_SIZE;
+        int mark = NetlinkUtils.INIT_MARK_VALUE;
+        // Get socket mark
+        // TODO: Add a parsing method in NetlinkMessage.parse to support this to skip the remaining
+        //  data.
+        while (bytes.position() < nextMsgOffset) {
+            final StructNlAttr nlattr = StructNlAttr.parse(bytes);
+            if (nlattr != null && nlattr.nla_type == NetlinkUtils.INET_DIAG_MARK) {
+                mark = nlattr.getValueAsInteger();
+            }
+        }
+        return mark;
+    }
+
+    private void ensureRunningOnHandlerThread() {
+        if (mConnectivityServiceHandler.getLooper().getThread() != Thread.currentThread()) {
+            throw new IllegalStateException(
+                    "Not running on handler thread: " + Thread.currentThread().getName());
+        }
+    }
+
+    /**
+     * Dependencies class for testing.
+     */
+    @VisibleForTesting
+    public static class Dependencies {
+        private final Context mContext;
+
+        public Dependencies(final Context context) {
+            mContext = context;
+        }
+
+        /**
+         * Create a netlink socket connected to the kernel.
+         *
+         * @return fd the fileDescriptor of the socket.
+         */
+        public FileDescriptor createConnectedNetlinkSocket()
+                throws ErrnoException, SocketException {
+            final FileDescriptor fd = NetlinkUtils.createNetLinkInetDiagSocket();
+            NetlinkUtils.connectSocketToNetlink(fd);
+            Os.setsockoptTimeval(fd, SOL_SOCKET, SO_SNDTIMEO,
+                    StructTimeval.fromMillis(IO_TIMEOUT_MS));
+            return fd;
+        }
+
+        /**
+         * Send composed message request to kernel.
+         *
+         * The given FileDescriptor is expected to be created by
+         * {@link #createConnectedNetlinkSocket} or equivalent way.
+         *
+         * @param fd a netlink socket {@code FileDescriptor} connected to the kernel.
+         * @param msg the byte array representing the request message to write to kernel.
+         */
+        public void sendRequest(@NonNull final FileDescriptor fd,
+                @NonNull final byte[] msg)
+                throws ErrnoException, InterruptedIOException {
+            Os.write(fd, msg, 0 /* byteOffset */, msg.length);
+        }
+
+        /**
+         * Get an INetd connector.
+         */
+        public INetd getNetd() {
+            return INetd.Stub.asInterface(
+                    (IBinder) mContext.getSystemService(Context.NETD_SERVICE));
+        }
+
+        /**
+         * Receive the response message from kernel via given {@code FileDescriptor}.
+         * The usage should follow the {@code #sendRequest} call with the same
+         * FileDescriptor.
+         *
+         * The overall response may be large but the individual messages should not be
+         * excessively large(8-16kB) because trying to get the kernel to return
+         * everything in one big buffer is inefficient as it forces the kernel to allocate
+         * large chunks of linearly physically contiguous memory. The usage should iterate the
+         * call of this method until the end of the overall message.
+         *
+         * The default receiving buffer size should be small enough that it is always
+         * processed within the {@link NetlinkUtils#IO_TIMEOUT_MS} timeout.
+         */
+        public ByteBuffer recvSockDiagResponse(@NonNull final FileDescriptor fd)
+                throws ErrnoException, InterruptedIOException {
+            return NetlinkUtils.recvMessage(
+                    fd, NetlinkUtils.DEFAULT_RECV_BUFSIZE, NetlinkUtils.IO_TIMEOUT_MS);
+        }
+
+        /**
+         * Construct a new KeepaliveTracker.
+         */
+        public KeepaliveTracker newKeepaliveTracker(@NonNull Context context,
+                @NonNull Handler connectivityserviceHander) {
+            return new KeepaliveTracker(mContext, connectivityserviceHander);
+        }
+    }
+}
diff --git a/service/src/com/android/server/connectivity/KeepaliveTracker.java b/service/src/com/android/server/connectivity/KeepaliveTracker.java
index 9c36760..23fdfd4 100644
--- a/service/src/com/android/server/connectivity/KeepaliveTracker.java
+++ b/service/src/com/android/server/connectivity/KeepaliveTracker.java
@@ -33,27 +33,15 @@
 import static android.net.SocketKeepalive.MIN_INTERVAL_SEC;
 import static android.net.SocketKeepalive.NO_KEEPALIVE;
 import static android.net.SocketKeepalive.SUCCESS;
-import static android.system.OsConstants.AF_INET;
-import static android.system.OsConstants.AF_INET6;
-import static android.system.OsConstants.SOL_SOCKET;
-import static android.system.OsConstants.SO_SNDTIMEO;
-
-import static com.android.net.module.util.netlink.NetlinkConstants.NLMSG_DONE;
-import static com.android.net.module.util.netlink.NetlinkConstants.SOCKDIAG_MSG_HEADER_SIZE;
-import static com.android.net.module.util.netlink.NetlinkConstants.SOCK_DIAG_BY_FAMILY;
-import static com.android.net.module.util.netlink.NetlinkUtils.IO_TIMEOUT_MS;
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.content.Context;
-import android.content.res.Resources;
 import android.net.ConnectivityResources;
-import android.net.INetd;
 import android.net.ISocketKeepaliveCallback;
 import android.net.InetAddresses;
 import android.net.InvalidPacketException;
 import android.net.KeepalivePacketData;
-import android.net.MarkMaskParcel;
 import android.net.NattKeepalivePacketData;
 import android.net.NetworkAgent;
 import android.net.SocketKeepalive.InvalidSocketException;
@@ -67,29 +55,18 @@
 import android.os.RemoteException;
 import android.system.ErrnoException;
 import android.system.Os;
-import android.system.StructTimeval;
 import android.util.Log;
 import android.util.Pair;
-import android.util.SparseArray;
 
 import com.android.connectivity.resources.R;
-import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.IndentingPrintWriter;
 import com.android.net.module.util.HexDump;
 import com.android.net.module.util.IpUtils;
-import com.android.net.module.util.SocketUtils;
-import com.android.net.module.util.netlink.InetDiagMessage;
-import com.android.net.module.util.netlink.NetlinkUtils;
-import com.android.net.module.util.netlink.StructNlAttr;
 
 import java.io.FileDescriptor;
-import java.io.InterruptedIOException;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
-import java.net.SocketException;
-import java.nio.BufferUnderflowException;
-import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -107,7 +84,6 @@
     private static final boolean DBG = false;
 
     public static final String PERMISSION = android.Manifest.permission.PACKET_KEEPALIVE_OFFLOAD;
-    private static final int[] ADDRESS_FAMILIES = new int[] {AF_INET6, AF_INET};
 
     /** Keeps track of keepalive requests. */
     private final HashMap <NetworkAgentInfo, HashMap<Integer, KeepaliveInfo>> mKeepalives =
@@ -131,35 +107,18 @@
     // 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;
-    /**
-     * The {@code inetDiagReqV2} messages for different IP family.
-     *
-     *   Key: Ip family type.
-     * Value: Bytes array represent the {@code inetDiagReqV2}.
-     *
-     * This should only be accessed in the connectivity service handler thread.
-     */
-    private final SparseArray<byte[]> mSockDiagMsg = new SparseArray<>();
-    private final Dependencies mDependencies;
-    private final INetd mNetd;
 
     public KeepaliveTracker(Context context, Handler handler) {
-        this(context, handler, new Dependencies(context));
-    }
-
-    @VisibleForTesting
-    public KeepaliveTracker(Context context, Handler handler, Dependencies dependencies) {
         mConnectivityServiceHandler = handler;
         mTcpController = new TcpKeepaliveController(handler);
         mContext = context;
-        mDependencies = dependencies;
-        mSupportedKeepalives = mDependencies.getSupportedKeepalives();
-        mNetd = mDependencies.getNetd();
 
-        final Resources res = mDependencies.newConnectivityResources();
-        mReservedPrivilegedSlots = res.getInteger(
+        mSupportedKeepalives = KeepaliveUtils.getSupportedKeepalives(mContext);
+
+        final ConnectivityResources res = new ConnectivityResources(mContext);
+        mReservedPrivilegedSlots = res.get().getInteger(
                 R.integer.config_reservedPrivilegedKeepaliveSlots);
-        mAllowedUnprivilegedSlotsForUid = res.getInteger(
+        mAllowedUnprivilegedSlotsForUid = res.get().getInteger(
                 R.integer.config_allowedUnprivilegedKeepalivePerUid);
     }
 
@@ -801,196 +760,4 @@
         }
         pw.decreaseIndent();
     }
-
-    /**
-     * Dependencies class for testing.
-     */
-    @VisibleForTesting
-    public static class Dependencies {
-        private final Context mContext;
-
-        public Dependencies(final Context context) {
-            mContext = context;
-        }
-
-        /**
-         * Create a netlink socket connected to the kernel.
-         *
-         * @return fd the fileDescriptor of the socket.
-         */
-        public FileDescriptor createConnectedNetlinkSocket()
-                throws ErrnoException, SocketException {
-            final FileDescriptor fd = NetlinkUtils.createNetLinkInetDiagSocket();
-            NetlinkUtils.connectSocketToNetlink(fd);
-            Os.setsockoptTimeval(fd, SOL_SOCKET, SO_SNDTIMEO,
-                    StructTimeval.fromMillis(IO_TIMEOUT_MS));
-            return fd;
-        }
-
-        /**
-         * Send composed message request to kernel.
-         *
-         * The given FileDescriptor is expected to be created by
-         * {@link #createConnectedNetlinkSocket} or equivalent way.
-         *
-         * @param fd a netlink socket {@code FileDescriptor} connected to the kernel.
-         * @param msg the byte array representing the request message to write to kernel.
-         */
-        public void sendRequest(@NonNull final FileDescriptor fd,
-                @NonNull final byte[] msg)
-                throws ErrnoException, InterruptedIOException {
-            Os.write(fd, msg, 0 /* byteOffset */, msg.length);
-        }
-
-        /**
-         * Get an INetd connector.
-         */
-        public INetd getNetd() {
-            return INetd.Stub.asInterface(
-                    (IBinder) mContext.getSystemService(Context.NETD_SERVICE));
-        }
-
-        /**
-         * Receive the response message from kernel via given {@code FileDescriptor}.
-         * The usage should follow the {@code #sendRequest} call with the same
-         * FileDescriptor.
-         *
-         * The overall response may be large but the individual messages should not be
-         * excessively large(8-16kB) because trying to get the kernel to return
-         * everything in one big buffer is inefficient as it forces the kernel to allocate
-         * large chunks of linearly physically contiguous memory. The usage should iterate the
-         * call of this method until the end of the overall message.
-         *
-         * The default receiving buffer size should be small enough that it is always
-         * processed within the {@link NetlinkUtils#IO_TIMEOUT_MS} timeout.
-         */
-        public ByteBuffer recvSockDiagResponse(@NonNull final FileDescriptor fd)
-                throws ErrnoException, InterruptedIOException {
-            return NetlinkUtils.recvMessage(
-                    fd, NetlinkUtils.DEFAULT_RECV_BUFSIZE, NetlinkUtils.IO_TIMEOUT_MS);
-        }
-
-        /**
-         * Read supported keepalive count for each transport type from overlay resource.
-         */
-        public int[] getSupportedKeepalives() {
-            return KeepaliveUtils.getSupportedKeepalives(mContext);
-        }
-
-        /**
-         * Construct a new Resource from a new ConnectivityResources.
-         */
-        public Resources newConnectivityResources() {
-            final ConnectivityResources resources = new ConnectivityResources(mContext);
-            return resources.get();
-        }
-    }
-
-    private void ensureRunningOnHandlerThread() {
-        if (mConnectivityServiceHandler.getLooper().getThread() != Thread.currentThread()) {
-            throw new IllegalStateException(
-                    "Not running on handler thread: " + Thread.currentThread().getName());
-        }
-    }
-
-    @VisibleForTesting
-    boolean isAnyTcpSocketConnected(int netId) {
-        FileDescriptor fd = null;
-
-        try {
-            fd = mDependencies.createConnectedNetlinkSocket();
-
-            // Get network mask
-            final MarkMaskParcel parcel = mNetd.getFwmarkForNetwork(netId);
-            final int networkMark = (parcel != null) ? parcel.mark : NetlinkUtils.UNKNOWN_MARK;
-            final int networkMask = (parcel != null) ? parcel.mask : NetlinkUtils.NULL_MASK;
-
-            // Send request for each IP family
-            for (final int family : ADDRESS_FAMILIES) {
-                if (isAnyTcpSocketConnectedForFamily(fd, family, networkMark, networkMask)) {
-                    return true;
-                }
-            }
-        } catch (ErrnoException | SocketException | InterruptedIOException | RemoteException e) {
-            Log.e(TAG, "Fail to get socket info via netlink.", e);
-        } finally {
-            SocketUtils.closeSocketQuietly(fd);
-        }
-
-        return false;
-    }
-
-    private boolean isAnyTcpSocketConnectedForFamily(FileDescriptor fd, int family, int networkMark,
-            int networkMask) throws ErrnoException, InterruptedIOException {
-        ensureRunningOnHandlerThread();
-        // Build SocketDiag messages and cache it.
-        if (mSockDiagMsg.get(family) == null) {
-            mSockDiagMsg.put(family, InetDiagMessage.buildInetDiagReqForAliveTcpSockets(family));
-        }
-        mDependencies.sendRequest(fd, mSockDiagMsg.get(family));
-
-        // Iteration limitation as a protection to avoid possible infinite loops.
-        // DEFAULT_RECV_BUFSIZE could read more than 20 sockets per time. Max iteration
-        // should be enough to go through reasonable TCP sockets in the device.
-        final int maxIteration = 100;
-        int parsingIteration = 0;
-        while (parsingIteration < maxIteration) {
-            final ByteBuffer bytes = mDependencies.recvSockDiagResponse(fd);
-
-            try {
-                while (NetlinkUtils.enoughBytesRemainForValidNlMsg(bytes)) {
-                    final int startPos = bytes.position();
-
-                    final int nlmsgLen = bytes.getInt();
-                    final int nlmsgType = bytes.getShort();
-                    if (isEndOfMessageOrError(nlmsgType)) return false;
-                    // TODO: Parse InetDiagMessage to get uid and dst address information to filter
-                    //  socket via NetlinkMessage.parse.
-
-                    // Skip the header to move to data part.
-                    bytes.position(startPos + SOCKDIAG_MSG_HEADER_SIZE);
-
-                    if (isTargetTcpSocket(bytes, nlmsgLen, networkMark, networkMask)) {
-                        return true;
-                    }
-                }
-            } catch (BufferUnderflowException e) {
-                // The exception happens in random place in either header position or any data
-                // position. Partial bytes from the middle of the byte buffer may not be enough to
-                // clarify, so print out the content before the error to possibly prevent printing
-                // the whole 8K buffer.
-                final int exceptionPos = bytes.position();
-                final String hex = HexDump.dumpHexString(bytes.array(), 0, exceptionPos);
-                Log.e(TAG, "Unexpected socket info parsing: " + hex, e);
-            }
-
-            parsingIteration++;
-        }
-        return false;
-    }
-
-    private boolean isEndOfMessageOrError(int nlmsgType) {
-        return nlmsgType == NLMSG_DONE || nlmsgType != SOCK_DIAG_BY_FAMILY;
-    }
-
-    private boolean isTargetTcpSocket(@NonNull ByteBuffer bytes, int nlmsgLen, int networkMark,
-            int networkMask) {
-        final int mark = readSocketDataAndReturnMark(bytes, nlmsgLen);
-        return (mark & networkMask) == networkMark;
-    }
-
-    private int readSocketDataAndReturnMark(@NonNull ByteBuffer bytes, int nlmsgLen) {
-        final int nextMsgOffset = bytes.position() + nlmsgLen - SOCKDIAG_MSG_HEADER_SIZE;
-        int mark = NetlinkUtils.INIT_MARK_VALUE;
-        // Get socket mark
-        // TODO: Add a parsing method in NetlinkMessage.parse to support this to skip the remaining
-        //  data.
-        while (bytes.position() < nextMsgOffset) {
-            final StructNlAttr nlattr = StructNlAttr.parse(bytes);
-            if (nlattr != null && nlattr.nla_type == NetlinkUtils.INET_DIAG_MARK) {
-                mark = nlattr.getValueAsInteger();
-            }
-        }
-        return mark;
-    }
 }