diff --git a/Tethering/Android.bp b/Tethering/Android.bp
index 0c37235..27297c4 100644
--- a/Tethering/Android.bp
+++ b/Tethering/Android.bp
@@ -16,9 +16,7 @@
 
 java_defaults {
     name: "TetheringAndroidLibraryDefaults",
-    // TODO (b/146757305): change to module API once available
-    // TODO (b/148190005): change to module-libs-api-stubs-current once it is ready.
-    sdk_version: "core_platform",
+    sdk_version: "module_current",
     srcs: [
         "src/**/*.java",
         ":framework-tethering-shared-srcs",
@@ -27,7 +25,7 @@
     ],
     static_libs: [
         "androidx.annotation_annotation",
-        "netd_aidl_interface-unstable-java",
+        "netd_aidl_interface-V3-java",
         "netlink-client",
         "networkstack-aidl-interfaces-unstable-java",
         "android.hardware.tetheroffload.config-V1.0-java",
@@ -35,15 +33,8 @@
         "net-utils-framework-common",
     ],
     libs: [
-        // Order matters: framework-tethering needs to be before the system stubs, otherwise
-        // hidden fields in the framework-tethering classes (which are also used to generate stubs)
-        // will not be found.
         "framework-tethering",
-        "android_system_stubs_current",
-        "framework-res",
         "unsupportedappusage",
-        "android_system_stubs_current",
-        "framework-res",
     ],
     plugins: ["java_api_finder"],
     manifest: "AndroidManifestBase.xml",
@@ -91,9 +82,7 @@
 // Common defaults for compiling the actual APK.
 java_defaults {
     name: "TetheringAppDefaults",
-    // TODO (b/146757305): change to module API once available
-    // TODO (b/148190005): change to module-libs-api-stubs-current once it is ready.
-    sdk_version: "core_platform",
+    sdk_version: "module_current",
     privileged: true,
     jni_libs: [
         "libtetherutilsjni",
@@ -102,12 +91,7 @@
         "res",
     ],
     libs: [
-        // Order matters: framework-tethering needs to be before the system stubs, otherwise
-        // hidden fields in the framework-tethering classes (which are also used to generate stubs)
-        // will not be found.
         "framework-tethering",
-        "android_system_stubs_current",
-        "framework-res",
     ],
     jarjar_rules: "jarjar-rules.txt",
     optimize: {
diff --git a/Tethering/AndroidManifest.xml b/Tethering/AndroidManifest.xml
index 9328611..2b2fe45 100644
--- a/Tethering/AndroidManifest.xml
+++ b/Tethering/AndroidManifest.xml
@@ -34,17 +34,21 @@
     <uses-permission android:name="android.permission.MODIFY_PHONE_STATE" />
     <uses-permission android:name="android.permission.READ_DEVICE_CONFIG" />
     <uses-permission android:name="android.permission.READ_NETWORK_USAGE_HISTORY" />
+    <uses-permission android:name="android.permission.READ_PHONE_STATE"/>
     <uses-permission android:name="android.permission.TETHER_PRIVILEGED" />
     <uses-permission android:name="android.permission.UPDATE_APP_OPS_STATS" />
     <uses-permission android:name="android.permission.UPDATE_DEVICE_STATS" />
     <uses-permission android:name="android.permission.WRITE_SETTINGS" />
 
+    <protected-broadcast android:name="com.android.server.connectivity.tethering.DISABLE_TETHERING" />
+
     <application
         android:process="com.android.networkstack.process"
         android:extractNativeLibs="false"
         android:persistent="true">
-        <service android:name="com.android.server.connectivity.tethering.TetheringService"
-                 android:permission="android.permission.MAINLINE_NETWORK_STACK">
+        <service android:name="com.android.networkstack.tethering.TetheringService"
+                 android:permission="android.permission.MAINLINE_NETWORK_STACK"
+                 android:exported="true">
             <intent-filter>
                 <action android:name="android.net.ITetheringConnector"/>
             </intent-filter>
diff --git a/Tethering/AndroidManifest_InProcess.xml b/Tethering/AndroidManifest_InProcess.xml
index 02ea551..b1f1240 100644
--- a/Tethering/AndroidManifest_InProcess.xml
+++ b/Tethering/AndroidManifest_InProcess.xml
@@ -22,9 +22,10 @@
           android:process="system">
     <uses-sdk android:minSdkVersion="29" android:targetSdkVersion="29" />
     <application>
-        <service android:name="com.android.server.connectivity.tethering.TetheringService"
+        <service android:name="com.android.networkstack.tethering.TetheringService"
                  android:process="system"
-                 android:permission="android.permission.MAINLINE_NETWORK_STACK">
+                 android:permission="android.permission.MAINLINE_NETWORK_STACK"
+                 android:exported="true">
             <intent-filter>
                 <action android:name="android.net.ITetheringConnector.InProcess"/>
             </intent-filter>
diff --git a/Tethering/common/TetheringLib/Android.bp b/Tethering/common/TetheringLib/Android.bp
index 00d0d9c..ee6b9f1 100644
--- a/Tethering/common/TetheringLib/Android.bp
+++ b/Tethering/common/TetheringLib/Android.bp
@@ -16,6 +16,7 @@
 // AIDL interfaces between the core system and the tethering mainline module.
 aidl_interface {
     name: "tethering-aidl-interfaces",
+    unstable: true,
     local_include_dir: "src",
     include_dirs: ["frameworks/base/core/java"], // For framework parcelables.
     srcs: [
@@ -65,12 +66,7 @@
 
 stubs_defaults {
     name: "framework-tethering-stubs-defaults",
-    srcs: [
-        "src/android/net/TetheredClient.java",
-        "src/android/net/TetheringManager.java",
-        "src/android/net/TetheringConstants.java",
-    ],
-    libs: ["tethering-aidl-interfaces-java"],
+    srcs: [":framework-tethering-srcs"],
 }
 
 filegroup {
@@ -126,17 +122,17 @@
 java_library {
     name: "framework-tethering-stubs-publicapi",
     srcs: [":framework-tethering-stubs-srcs-publicapi"],
-    sdk_version: "current",
+    defaults: ["framework-module-stubs-lib-defaults-publicapi"],
 }
 
 java_library {
     name: "framework-tethering-stubs-systemapi",
     srcs: [":framework-tethering-stubs-srcs-systemapi"],
-    sdk_version: "system_current",
+    defaults: ["framework-module-stubs-lib-defaults-systemapi"],
 }
 
 java_library {
     name: "framework-tethering-stubs-module_libs_api",
     srcs: [":framework-tethering-stubs-srcs-module_libs_api"],
-    sdk_version: "module_current",
+    defaults: ["framework-module-stubs-lib-defaults-systemapi"],
 }
diff --git a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
index 096f4fe..0107a7e 100644
--- a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
+++ b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
@@ -571,9 +571,8 @@
             /**
              * Configure tethering with static IPv4 assignment.
              *
-             * The clientAddress must be in the localIPv4Address prefix. A DHCP server will be
-             * started, but will only be able to offer the client address. The two addresses must
-             * be in the same prefix.
+             * A DHCP server will be started, but will only be able to offer the client address.
+             * The two addresses must be in the same prefix.
              *
              * @param localIPv4Address The preferred local IPv4 link address to use.
              * @param clientAddress The static client address.
@@ -584,10 +583,7 @@
                     @NonNull final LinkAddress clientAddress) {
                 Objects.requireNonNull(localIPv4Address);
                 Objects.requireNonNull(clientAddress);
-                if (localIPv4Address.getPrefixLength() != clientAddress.getPrefixLength()
-                        || !localIPv4Address.isIpv4() || !clientAddress.isIpv4()
-                        || !new IpPrefix(localIPv4Address.toString()).equals(
-                        new IpPrefix(clientAddress.toString()))) {
+                if (!checkStaticAddressConfiguration(localIPv4Address, clientAddress)) {
                     throw new IllegalArgumentException("Invalid server or client addresses");
                 }
 
@@ -657,6 +653,19 @@
         }
 
         /**
+         * Check whether the two addresses are ipv4 and in the same prefix.
+         * @hide
+         */
+        public static boolean checkStaticAddressConfiguration(
+                @NonNull final LinkAddress localIPv4Address,
+                @NonNull final LinkAddress clientAddress) {
+            return localIPv4Address.getPrefixLength() == clientAddress.getPrefixLength()
+                    && localIPv4Address.isIpv4() && clientAddress.isIpv4()
+                    && new IpPrefix(localIPv4Address.toString()).equals(
+                    new IpPrefix(clientAddress.toString()));
+        }
+
+        /**
          * Get a TetheringRequestParcel from the configuration
          * @hide
          */
diff --git a/Tethering/proguard.flags b/Tethering/proguard.flags
index 1f83a66..051fbd1 100644
--- a/Tethering/proguard.flags
+++ b/Tethering/proguard.flags
@@ -1,5 +1,5 @@
 # Keep class's integer static field for MessageUtils to parsing their name.
--keep class com.android.server.connectivity.tethering.Tethering$TetherMasterSM {
+-keep class com.android.networkstack.tethering.Tethering$TetherMasterSM {
     static final int CMD_*;
     static final int EVENT_*;
 }
diff --git a/Tethering/res/values-mcc204-mnc04/strings.xml b/Tethering/res/values-mcc204-mnc04/strings.xml
deleted file mode 100644
index a996b42..0000000
--- a/Tethering/res/values-mcc204-mnc04/strings.xml
+++ /dev/null
@@ -1,30 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!-- 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.
--->
-<resources>
-    <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_title">Hotspot has no internet</string>
-    <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_message">Devices can\u2019t connect to internet</string>
-    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
-    <string name="no_upstream_notification_disable_button">Turn off hotspot</string>
-
-    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
-    <string name="upstream_roaming_notification_title">Hotspot is on</string>
-    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
-    <string name="upstream_roaming_notification_message">Additional charges may apply while roaming</string>
-    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
-    <string name="upstream_roaming_notification_continue_button">Continue</string>
-</resources>
diff --git a/Tethering/res/values-mcc310-mnc004/config.xml b/Tethering/res/values-mcc310-mnc004/config.xml
new file mode 100644
index 0000000..5c5be04
--- /dev/null
+++ b/Tethering/res/values-mcc310-mnc004/config.xml
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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.
+-->
+<resources>
+    <!-- Delay(millisecond) to show no upstream notification after there's no Backhaul. Set delay to
+         "0" for disable this feature. -->
+    <integer name="delay_to_show_no_upstream_after_no_backhaul">5000</integer>
+
+    <!-- Config for showing upstream roaming notification. -->
+    <bool name="config_upstream_roaming_notification">true</bool>
+</resources>
\ No newline at end of file
diff --git a/Tethering/res/values-mcc310-mnc004/strings.xml b/Tethering/res/values-mcc310-mnc004/strings.xml
index a996b42..9dadd49 100644
--- a/Tethering/res/values-mcc310-mnc004/strings.xml
+++ b/Tethering/res/values-mcc310-mnc004/strings.xml
@@ -15,16 +15,16 @@
 -->
 <resources>
     <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_title">Hotspot has no internet</string>
+    <string name="no_upstream_notification_title">Tethering has no internet</string>
     <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_message">Devices can\u2019t connect to internet</string>
-    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
-    <string name="no_upstream_notification_disable_button">Turn off hotspot</string>
+    <string name="no_upstream_notification_message">Devices can\u2019t connect</string>
+    <!-- String for no upstream notification disable button [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_disable_button">Turn off tethering</string>
 
-    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
-    <string name="upstream_roaming_notification_title">Hotspot is on</string>
-    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
+    <!-- String for cellular roaming notification title [CHAR LIMIT=200] -->
+    <string name="upstream_roaming_notification_title">Hotspot or tethering is on</string>
+    <!-- String for cellular roaming notification message [CHAR LIMIT=500] -->
     <string name="upstream_roaming_notification_message">Additional charges may apply while roaming</string>
-    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
+    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200] -->
     <string name="upstream_roaming_notification_continue_button">Continue</string>
 </resources>
diff --git a/Tethering/res/values-mcc311-mnc480/config.xml b/Tethering/res/values-mcc311-mnc480/config.xml
new file mode 100644
index 0000000..5c5be04
--- /dev/null
+++ b/Tethering/res/values-mcc311-mnc480/config.xml
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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.
+-->
+<resources>
+    <!-- Delay(millisecond) to show no upstream notification after there's no Backhaul. Set delay to
+         "0" for disable this feature. -->
+    <integer name="delay_to_show_no_upstream_after_no_backhaul">5000</integer>
+
+    <!-- Config for showing upstream roaming notification. -->
+    <bool name="config_upstream_roaming_notification">true</bool>
+</resources>
\ No newline at end of file
diff --git a/Tethering/res/values-mcc311-mnc480/strings.xml b/Tethering/res/values-mcc311-mnc480/strings.xml
index a996b42..9dadd49 100644
--- a/Tethering/res/values-mcc311-mnc480/strings.xml
+++ b/Tethering/res/values-mcc311-mnc480/strings.xml
@@ -15,16 +15,16 @@
 -->
 <resources>
     <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_title">Hotspot has no internet</string>
+    <string name="no_upstream_notification_title">Tethering has no internet</string>
     <!-- String for no upstream notification title [CHAR LIMIT=200] -->
-    <string name="no_upstream_notification_message">Devices can\u2019t connect to internet</string>
-    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
-    <string name="no_upstream_notification_disable_button">Turn off hotspot</string>
+    <string name="no_upstream_notification_message">Devices can\u2019t connect</string>
+    <!-- String for no upstream notification disable button [CHAR LIMIT=200] -->
+    <string name="no_upstream_notification_disable_button">Turn off tethering</string>
 
-    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
-    <string name="upstream_roaming_notification_title">Hotspot is on</string>
-    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
+    <!-- String for cellular roaming notification title [CHAR LIMIT=200] -->
+    <string name="upstream_roaming_notification_title">Hotspot or tethering is on</string>
+    <!-- String for cellular roaming notification message [CHAR LIMIT=500] -->
     <string name="upstream_roaming_notification_message">Additional charges may apply while roaming</string>
-    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
+    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200] -->
     <string name="upstream_roaming_notification_continue_button">Continue</string>
 </resources>
diff --git a/Tethering/res/values/config.xml b/Tethering/res/values/config.xml
index f825d6b..aed5ab8 100644
--- a/Tethering/res/values/config.xml
+++ b/Tethering/res/values/config.xml
@@ -87,7 +87,7 @@
                         TYPE_MOBILE_HIPRI is appended.
 
          For other changes applied to this list, now and in the future, see
-         com.android.server.connectivity.tethering.TetheringConfiguration.
+         com.android.networkstack.tethering.TetheringConfiguration.
 
          Note also: the order of this is important. The first upstream type
          for which a satisfying network exists is used.
@@ -200,4 +200,15 @@
     <string name="tethering_notification_title">@string/tethered_notification_title</string>
     <!-- String for tether enable notification message. -->
     <string name="tethering_notification_message">@string/tethered_notification_message</string>
+
+    <!-- No upstream notification is shown when there is a downstream but no upstream that is able
+         to do the tethering. -->
+    <!-- Delay(millisecond) to show no upstream notification after there's no Backhaul. Set delay to
+         "-1" for disable this feature. -->
+    <integer name="delay_to_show_no_upstream_after_no_backhaul">-1</integer>
+
+    <!-- Cellular roaming notification is shown when upstream is cellular network and in roaming
+         state. -->
+    <!-- Config for showing upstream roaming notification. -->
+    <bool name="config_upstream_roaming_notification">false</bool>
 </resources>
diff --git a/Tethering/res/values/strings.xml b/Tethering/res/values/strings.xml
index 52a1654..4fa60d4 100644
--- a/Tethering/res/values/strings.xml
+++ b/Tethering/res/values/strings.xml
@@ -40,13 +40,13 @@
     <string name="no_upstream_notification_title"></string>
     <!-- String for no upstream notification message [CHAR LIMIT=200] -->
     <string name="no_upstream_notification_message"></string>
-    <!-- String for cellular roaming notification disable button [CHAR LIMIT=200]  -->
+    <!-- String for no upstream notification disable button [CHAR LIMIT=200] -->
     <string name="no_upstream_notification_disable_button"></string>
 
-    <!-- String for cellular roaming notification title [CHAR LIMIT=200]  -->
+    <!-- String for cellular roaming notification title [CHAR LIMIT=200] -->
     <string name="upstream_roaming_notification_title"></string>
-    <!-- String for cellular roaming notification message [CHAR LIMIT=500]  -->
+    <!-- String for cellular roaming notification message [CHAR LIMIT=500] -->
     <string name="upstream_roaming_notification_message"></string>
-    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200]  -->
+    <!-- String for cellular roaming notification continue button [CHAR LIMIT=200] -->
     <string name="upstream_roaming_notification_continue_button"></string>
 </resources>
diff --git a/Tethering/src/android/net/dhcp/DhcpServingParamsParcelExt.java b/Tethering/src/android/net/dhcp/DhcpServingParamsParcelExt.java
index d6bc063..82a26be 100644
--- a/Tethering/src/android/net/dhcp/DhcpServingParamsParcelExt.java
+++ b/Tethering/src/android/net/dhcp/DhcpServingParamsParcelExt.java
@@ -18,10 +18,12 @@
 
 import static android.net.shared.Inet4AddressUtils.inet4AddressToIntHTH;
 
-import android.annotation.NonNull;
 import android.net.LinkAddress;
 import android.util.ArraySet;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 import java.net.Inet4Address;
 import java.util.Collection;
 import java.util.Collections;
@@ -160,6 +162,17 @@
         return this;
     }
 
+    /**
+     * Set the client address to tell DHCP server only offer this address.
+     * The client's prefix length is the same as server's.
+     *
+     * <p>If not set, the default value is null.
+     */
+    public DhcpServingParamsParcelExt setSingleClientAddr(@Nullable Inet4Address clientAddr) {
+        this.clientAddr = clientAddr == null ? 0 : inet4AddressToIntHTH(clientAddr);
+        return this;
+    }
+
     private static int[] toIntArray(@NonNull Collection<Inet4Address> addrs) {
         int[] res = new int[addrs.size()];
         int i = 0;
diff --git a/Tethering/src/android/net/ip/IpServer.java b/Tethering/src/android/net/ip/IpServer.java
index c5478d2..83727bc 100644
--- a/Tethering/src/android/net/ip/IpServer.java
+++ b/Tethering/src/android/net/ip/IpServer.java
@@ -18,6 +18,7 @@
 
 import static android.net.InetAddresses.parseNumericAddress;
 import static android.net.RouteInfo.RTN_UNICAST;
+import static android.net.TetheringManager.TetheringRequest.checkStaticAddressConfiguration;
 import static android.net.dhcp.IDhcpServer.STATUS_SUCCESS;
 import static android.net.shared.Inet4AddressUtils.intToInet4AddressHTH;
 import static android.net.util.NetworkConstants.FF;
@@ -33,6 +34,7 @@
 import android.net.LinkProperties;
 import android.net.MacAddress;
 import android.net.RouteInfo;
+import android.net.TetherOffloadRuleParcel;
 import android.net.TetheredClient;
 import android.net.TetheringManager;
 import android.net.TetheringRequestParcel;
@@ -40,7 +42,7 @@
 import android.net.dhcp.DhcpServerCallbacks;
 import android.net.dhcp.DhcpServingParamsParcel;
 import android.net.dhcp.DhcpServingParamsParcelExt;
-import android.net.dhcp.IDhcpLeaseCallbacks;
+import android.net.dhcp.IDhcpEventCallbacks;
 import android.net.dhcp.IDhcpServer;
 import android.net.ip.IpNeighborMonitor.NeighborEvent;
 import android.net.ip.RouterAdvertisementDaemon.RaParams;
@@ -120,6 +122,8 @@
     // TODO: have this configurable
     private static final int DHCP_LEASE_TIME_SECS = 3600;
 
+    private static final MacAddress NULL_MAC_ADDRESS = MacAddress.fromString("00:00:00:00:00:00");
+
     private static final String TAG = "IpServer";
     private static final boolean DBG = false;
     private static final boolean VDBG = false;
@@ -279,6 +283,19 @@
             return new Ipv6ForwardingRule(newUpstreamIfindex, downstreamIfindex, address, srcMac,
                     dstMac);
         }
+
+        // Don't manipulate TetherOffloadRuleParcel directly because implementing onNewUpstream()
+        // would be error-prone due to generated stable AIDL classes not having a copy constructor.
+        public TetherOffloadRuleParcel toTetherOffloadRuleParcel() {
+            final TetherOffloadRuleParcel parcel = new TetherOffloadRuleParcel();
+            parcel.inputInterfaceIndex = upstreamIfindex;
+            parcel.outputInterfaceIndex = downstreamIfindex;
+            parcel.destination = address.getAddress();
+            parcel.prefixLength = 128;
+            parcel.srcL2Address = srcMac.toByteArray();
+            parcel.dstL2Address = dstMac.toByteArray();
+            return parcel;
+        }
     }
     private final LinkedHashMap<Inet6Address, Ipv6ForwardingRule> mIpv6ForwardingRules =
             new LinkedHashMap<>();
@@ -448,7 +465,7 @@
         }
     }
 
-    private class DhcpLeaseCallback extends IDhcpLeaseCallbacks.Stub {
+    private class DhcpLeaseCallback extends IDhcpEventCallbacks.Stub {
         @Override
         public void onLeasesChanged(List<DhcpLeaseParcelable> leaseParcelables) {
             final ArrayList<TetheredClient> leases = new ArrayList<>();
@@ -482,6 +499,11 @@
         }
 
         @Override
+        public void onNewPrefixRequest(IpPrefix currentPrefix) {
+            //TODO: add specific implementation.
+        }
+
+        @Override
         public int getInterfaceVersion() {
             return this.VERSION;
         }
@@ -492,17 +514,24 @@
         }
     }
 
-    private boolean startDhcp(Inet4Address addr, int prefixLen) {
+    private boolean startDhcp(final LinkAddress serverLinkAddr, final LinkAddress clientLinkAddr) {
         if (mUsingLegacyDhcp) {
             return true;
         }
+
+        final Inet4Address addr = (Inet4Address) serverLinkAddr.getAddress();
+        final int prefixLen = serverLinkAddr.getPrefixLength();
+        final Inet4Address clientAddr = clientLinkAddr == null ? null :
+                (Inet4Address) clientLinkAddr.getAddress();
+
         final DhcpServingParamsParcel params;
         params = new DhcpServingParamsParcelExt()
                 .setDefaultRouters(addr)
                 .setDhcpLeaseTimeSecs(DHCP_LEASE_TIME_SECS)
                 .setDnsServers(addr)
-                .setServerAddr(new LinkAddress(addr, prefixLen))
-                .setMetered(true);
+                .setServerAddr(serverLinkAddr)
+                .setMetered(true)
+                .setSingleClientAddr(clientAddr);
         // TODO: also advertise link MTU
 
         mDhcpServerStartIndex++;
@@ -537,9 +566,10 @@
         }
     }
 
-    private boolean configureDhcp(boolean enable, Inet4Address addr, int prefixLen) {
+    private boolean configureDhcp(boolean enable, final LinkAddress serverAddr,
+            final LinkAddress clientAddr) {
         if (enable) {
-            return startDhcp(addr, prefixLen);
+            return startDhcp(serverAddr, clientAddr);
         } else {
             stopDhcp();
             return true;
@@ -587,7 +617,7 @@
                 // code that calls into NetworkManagementService directly.
                 srvAddr = (Inet4Address) parseNumericAddress(BLUETOOTH_IFACE_ADDR);
                 mIpv4Address = new LinkAddress(srvAddr, BLUETOOTH_DHCP_PREFIX_LENGTH);
-                return configureDhcp(enabled, srvAddr, BLUETOOTH_DHCP_PREFIX_LENGTH);
+                return configureDhcp(enabled, mIpv4Address, null /* clientAddress */);
             }
             mIpv4Address = new LinkAddress(srvAddr, prefixLen);
         } catch (IllegalArgumentException e) {
@@ -624,7 +654,7 @@
             mLinkProperties.removeRoute(route);
         }
 
-        return configureDhcp(enabled, srvAddr, prefixLen);
+        return configureDhcp(enabled, mIpv4Address, mStaticIpv4ClientAddr);
     }
 
     private String getRandomWifiIPv4Address() {
@@ -815,9 +845,7 @@
 
     private void addIpv6ForwardingRule(Ipv6ForwardingRule rule) {
         try {
-            mNetd.tetherRuleAddDownstreamIpv6(mInterfaceParams.index, rule.upstreamIfindex,
-                    rule.address.getAddress(),  mInterfaceParams.macAddr.toByteArray(),
-                    rule.dstMac.toByteArray());
+            mNetd.tetherOffloadRuleAdd(rule.toTetherOffloadRuleParcel());
             mIpv6ForwardingRules.put(rule.address, rule);
         } catch (RemoteException | ServiceSpecificException e) {
             mLog.e("Could not add IPv6 downstream rule: ", e);
@@ -826,7 +854,7 @@
 
     private void removeIpv6ForwardingRule(Ipv6ForwardingRule rule, boolean removeFromMap) {
         try {
-            mNetd.tetherRuleRemoveDownstreamIpv6(rule.upstreamIfindex, rule.address.getAddress());
+            mNetd.tetherOffloadRuleRemove(rule.toTetherOffloadRuleParcel());
             if (removeFromMap) {
                 mIpv6ForwardingRules.remove(rule.address);
             }
@@ -876,9 +904,12 @@
             return;
         }
 
+        // When deleting rules, we still need to pass a non-null MAC, even though it's ignored.
+        // Do this here instead of in the Ipv6ForwardingRule constructor to ensure that we never
+        // add rules with a null MAC, only delete them.
+        MacAddress dstMac = e.isValid() ? e.macAddr : NULL_MAC_ADDRESS;
         Ipv6ForwardingRule rule = new Ipv6ForwardingRule(upstreamIfindex,
-                mInterfaceParams.index, (Inet6Address) e.ip, mInterfaceParams.macAddr,
-                e.macAddr);
+                mInterfaceParams.index, (Inet6Address) e.ip, mInterfaceParams.macAddr, dstMac);
         if (e.isValid()) {
             addIpv6ForwardingRule(rule);
         } else {
@@ -945,7 +976,14 @@
     }
 
     private void maybeConfigureStaticIp(final TetheringRequestParcel request) {
-        if (request == null) return;
+        // Ignore static address configuration if they are invalid or null. In theory, static
+        // addresses should not be invalid here because TetheringManager do not allow caller to
+        // specify invalid static address configuration.
+        if (request == null || request.localIPv4Address == null
+                || request.staticClientAddress == null || !checkStaticAddressConfiguration(
+                request.localIPv4Address, request.staticClientAddress)) {
+            return;
+        }
 
         mStaticIpv4ServerAddr = request.localIPv4Address;
         mStaticIpv4ClientAddr = request.staticClientAddress;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/ConnectedClientsTracker.java b/Tethering/src/com/android/networkstack/tethering/ConnectedClientsTracker.java
similarity index 98%
rename from Tethering/src/com/android/server/connectivity/tethering/ConnectedClientsTracker.java
rename to Tethering/src/com/android/networkstack/tethering/ConnectedClientsTracker.java
index cdd1a5d..8a96988 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/ConnectedClientsTracker.java
+++ b/Tethering/src/com/android/networkstack/tethering/ConnectedClientsTracker.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.TetheringManager.TETHERING_WIFI;
 
diff --git a/Tethering/src/com/android/server/connectivity/tethering/EntitlementManager.java b/Tethering/src/com/android/networkstack/tethering/EntitlementManager.java
similarity index 86%
rename from Tethering/src/com/android/server/connectivity/tethering/EntitlementManager.java
rename to Tethering/src/com/android/networkstack/tethering/EntitlementManager.java
index bd60594..049a9f6 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/EntitlementManager.java
+++ b/Tethering/src/com/android/networkstack/tethering/EntitlementManager.java
@@ -14,12 +14,13 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.TetheringConstants.EXTRA_ADD_TETHER_TYPE;
 import static android.net.TetheringConstants.EXTRA_PROVISION_CALLBACK;
 import static android.net.TetheringConstants.EXTRA_RUN_PROVISION;
 import static android.net.TetheringManager.TETHERING_BLUETOOTH;
+import static android.net.TetheringManager.TETHERING_ETHERNET;
 import static android.net.TetheringManager.TETHERING_INVALID;
 import static android.net.TetheringManager.TETHERING_USB;
 import static android.net.TetheringManager.TETHERING_WIFI;
@@ -37,8 +38,6 @@
 import android.net.util.SharedLog;
 import android.os.Bundle;
 import android.os.Handler;
-import android.os.Looper;
-import android.os.Message;
 import android.os.Parcel;
 import android.os.PersistableBundle;
 import android.os.ResultReceiver;
@@ -51,7 +50,6 @@
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.StateMachine;
-import com.android.networkstack.tethering.R;
 
 import java.io.PrintWriter;
 
@@ -70,16 +68,11 @@
     @VisibleForTesting
     protected static final String DISABLE_PROVISIONING_SYSPROP_KEY = "net.tethering.noprovisioning";
     private static final String ACTION_PROVISIONING_ALARM =
-            "com.android.server.connectivity.tethering.PROVISIONING_RECHECK_ALARM";
+            "com.android.networkstack.tethering.PROVISIONING_RECHECK_ALARM";
     private static final String EXTRA_SUBID = "subId";
 
     private final ComponentName mSilentProvisioningService;
     private static final int MS_PER_HOUR = 60 * 60 * 1000;
-    private static final int EVENT_START_PROVISIONING = 0;
-    private static final int EVENT_STOP_PROVISIONING = 1;
-    private static final int EVENT_UPSTREAM_CHANGED = 2;
-    private static final int EVENT_MAYBE_RUN_PROVISIONING = 3;
-    private static final int EVENT_GET_ENTITLEMENT_VALUE = 4;
 
     // The ArraySet contains enabled downstream types, ex:
     // {@link TetheringManager.TETHERING_WIFI}
@@ -90,7 +83,7 @@
     private final int mPermissionChangeMessageCode;
     private final SharedLog mLog;
     private final SparseIntArray mEntitlementCacheValue;
-    private final EntitlementHandler mHandler;
+    private final Handler mHandler;
     private final StateMachine mTetherMasterSM;
     // Key: TetheringManager.TETHERING_*(downstream).
     // Value: TetheringManager.TETHER_ERROR_{NO_ERROR or PROVISION_FAILED}(provisioning result).
@@ -112,10 +105,7 @@
         mEntitlementCacheValue = new SparseIntArray();
         mTetherMasterSM = tetherMasterSM;
         mPermissionChangeMessageCode = permissionChangeMessageCode;
-        final Handler masterHandler = tetherMasterSM.getHandler();
-        // Create entitlement's own handler which is associated with TetherMaster thread
-        // let all entitlement processes run in the same thread.
-        mHandler = new EntitlementHandler(masterHandler.getLooper());
+        mHandler = tetherMasterSM.getHandler();
         mContext.registerReceiver(mReceiver, new IntentFilter(ACTION_PROVISIONING_ALARM),
                 null, mHandler);
         mSilentProvisioningService = ComponentName.unflattenFromString(
@@ -172,14 +162,9 @@
      *        provisioning app UI if there is one.
      */
     public void startProvisioningIfNeeded(int downstreamType, boolean showProvisioningUi) {
-        mHandler.sendMessage(mHandler.obtainMessage(EVENT_START_PROVISIONING,
-                downstreamType, encodeBool(showProvisioningUi)));
-    }
+        if (!isValidDownstreamType(downstreamType)) return;
 
-    private void handleStartProvisioningIfNeeded(int type, boolean showProvisioningUi) {
-        if (!isValidDownstreamType(type)) return;
-
-        if (!mCurrentTethers.contains(type)) mCurrentTethers.add(type);
+        if (!mCurrentTethers.contains(downstreamType)) mCurrentTethers.add(downstreamType);
 
         final TetheringConfiguration config = mFetcher.fetchTetheringConfiguration();
         if (isTetherProvisioningRequired(config)) {
@@ -192,9 +177,9 @@
             // till upstream change to cellular.
             if (mUsingCellularAsUpstream) {
                 if (showProvisioningUi) {
-                    runUiTetherProvisioning(type, config.activeDataSubId);
+                    runUiTetherProvisioning(downstreamType, config.activeDataSubId);
                 } else {
-                    runSilentTetherProvisioning(type, config.activeDataSubId);
+                    runSilentTetherProvisioning(downstreamType, config.activeDataSubId);
                 }
                 mNeedReRunProvisioningUi = false;
             } else {
@@ -211,10 +196,6 @@
      * @param type tethering type from TetheringManager.TETHERING_{@code *}
      */
     public void stopProvisioningIfNeeded(int type) {
-        mHandler.sendMessage(mHandler.obtainMessage(EVENT_STOP_PROVISIONING, type, 0));
-    }
-
-    private void handleStopProvisioningIfNeeded(int type) {
         if (!isValidDownstreamType(type)) return;
 
         mCurrentTethers.remove(type);
@@ -230,11 +211,6 @@
      * @param isCellular whether tethering upstream is cellular.
      */
     public void notifyUpstream(boolean isCellular) {
-        mHandler.sendMessage(mHandler.obtainMessage(
-                EVENT_UPSTREAM_CHANGED, encodeBool(isCellular), 0));
-    }
-
-    private void handleNotifyUpstream(boolean isCellular) {
         if (DBG) {
             mLog.i("notifyUpstream: " + isCellular
                     + ", mCellularUpstreamPermitted: " + mCellularUpstreamPermitted
@@ -244,16 +220,17 @@
 
         if (mUsingCellularAsUpstream) {
             final TetheringConfiguration config = mFetcher.fetchTetheringConfiguration();
-            handleMaybeRunProvisioning(config);
+            maybeRunProvisioning(config);
         }
     }
 
     /** Run provisioning if needed */
     public void maybeRunProvisioning() {
-        mHandler.sendMessage(mHandler.obtainMessage(EVENT_MAYBE_RUN_PROVISIONING));
+        final TetheringConfiguration config = mFetcher.fetchTetheringConfiguration();
+        maybeRunProvisioning(config);
     }
 
-    private void handleMaybeRunProvisioning(final TetheringConfiguration config) {
+    private void maybeRunProvisioning(final TetheringConfiguration config) {
         if (mCurrentTethers.size() == 0 || !isTetherProvisioningRequired(config)) {
             return;
         }
@@ -319,7 +296,7 @@
         }
 
         if (mUsingCellularAsUpstream) {
-            handleMaybeRunProvisioning(config);
+            maybeRunProvisioning(config);
         }
     }
 
@@ -494,49 +471,10 @@
         }
     };
 
-    private class EntitlementHandler extends Handler {
-        EntitlementHandler(Looper looper) {
-            super(looper);
-        }
-
-        @Override
-        public void handleMessage(Message msg) {
-            switch (msg.what) {
-                case EVENT_START_PROVISIONING:
-                    handleStartProvisioningIfNeeded(msg.arg1, toBool(msg.arg2));
-                    break;
-                case EVENT_STOP_PROVISIONING:
-                    handleStopProvisioningIfNeeded(msg.arg1);
-                    break;
-                case EVENT_UPSTREAM_CHANGED:
-                    handleNotifyUpstream(toBool(msg.arg1));
-                    break;
-                case EVENT_MAYBE_RUN_PROVISIONING:
-                    final TetheringConfiguration config = mFetcher.fetchTetheringConfiguration();
-                    handleMaybeRunProvisioning(config);
-                    break;
-                case EVENT_GET_ENTITLEMENT_VALUE:
-                    handleRequestLatestTetheringEntitlementValue(msg.arg1,
-                            (ResultReceiver) msg.obj, toBool(msg.arg2));
-                    break;
-                default:
-                    mLog.log("Unknown event: " + msg.what);
-                    break;
-            }
-        }
-    }
-
-    private static boolean toBool(int encodedBoolean) {
-        return encodedBoolean != 0;
-    }
-
-    private static int encodeBool(boolean b) {
-        return b ? 1 : 0;
-    }
-
     private static boolean isValidDownstreamType(int type) {
         switch (type) {
             case TETHERING_BLUETOOTH:
+            case TETHERING_ETHERNET:
             case TETHERING_USB:
             case TETHERING_WIFI:
                 return true;
@@ -643,13 +581,11 @@
     /** Get the last value of the tethering entitlement check. */
     public void requestLatestTetheringEntitlementResult(int downstream, ResultReceiver receiver,
             boolean showEntitlementUi) {
-        mHandler.sendMessage(mHandler.obtainMessage(EVENT_GET_ENTITLEMENT_VALUE,
-                downstream, encodeBool(showEntitlementUi), receiver));
+        if (!isValidDownstreamType(downstream)) {
+            receiver.send(TETHER_ERROR_ENTITLEMENT_UNKNOWN, null);
+            return;
+        }
 
-    }
-
-    private void handleRequestLatestTetheringEntitlementValue(int downstream,
-            ResultReceiver receiver, boolean showEntitlementUi) {
         final TetheringConfiguration config = mFetcher.fetchTetheringConfiguration();
         if (!isTetherProvisioningRequired(config)) {
             receiver.send(TETHER_ERROR_NO_ERROR, null);
diff --git a/Tethering/src/com/android/server/connectivity/tethering/IPv6TetheringCoordinator.java b/Tethering/src/com/android/networkstack/tethering/IPv6TetheringCoordinator.java
similarity index 99%
rename from Tethering/src/com/android/server/connectivity/tethering/IPv6TetheringCoordinator.java
rename to Tethering/src/com/android/networkstack/tethering/IPv6TetheringCoordinator.java
index 66b9ade..d450c46 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/IPv6TetheringCoordinator.java
+++ b/Tethering/src/com/android/networkstack/tethering/IPv6TetheringCoordinator.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import android.net.IpPrefix;
 import android.net.LinkAddress;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/OffloadController.java b/Tethering/src/com/android/networkstack/tethering/OffloadController.java
similarity index 99%
rename from Tethering/src/com/android/server/connectivity/tethering/OffloadController.java
rename to Tethering/src/com/android/networkstack/tethering/OffloadController.java
index 15cdb6a..c007c17 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/OffloadController.java
+++ b/Tethering/src/com/android/networkstack/tethering/OffloadController.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.NetworkStats.DEFAULT_NETWORK_NO;
 import static android.net.NetworkStats.METERED_NO;
@@ -50,7 +50,7 @@
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.IndentingPrintWriter;
-import com.android.server.connectivity.tethering.OffloadHardwareInterface.ForwardedStats;
+import com.android.networkstack.tethering.OffloadHardwareInterface.ForwardedStats;
 
 import java.net.Inet4Address;
 import java.net.Inet6Address;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/OffloadHardwareInterface.java b/Tethering/src/com/android/networkstack/tethering/OffloadHardwareInterface.java
similarity index 99%
rename from Tethering/src/com/android/server/connectivity/tethering/OffloadHardwareInterface.java
rename to Tethering/src/com/android/networkstack/tethering/OffloadHardwareInterface.java
index b545717..55344fc 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/OffloadHardwareInterface.java
+++ b/Tethering/src/com/android/networkstack/tethering/OffloadHardwareInterface.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.util.TetheringUtils.uint16;
 
@@ -142,7 +142,7 @@
     public boolean initOffloadConfig() {
         IOffloadConfig offloadConfig;
         try {
-            offloadConfig = IOffloadConfig.getService();
+            offloadConfig = IOffloadConfig.getService(true /*retry*/);
         } catch (RemoteException e) {
             mLog.e("getIOffloadConfig error " + e);
             return false;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/Tethering.java b/Tethering/src/com/android/networkstack/tethering/Tethering.java
similarity index 97%
rename from Tethering/src/com/android/server/connectivity/tethering/Tethering.java
rename to Tethering/src/com/android/networkstack/tethering/Tethering.java
index 020db54..97b1946 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/Tethering.java
+++ b/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.Manifest.permission.NETWORK_SETTINGS;
 import static android.Manifest.permission.NETWORK_STACK;
@@ -60,7 +60,7 @@
 import static android.telephony.CarrierConfigManager.ACTION_CARRIER_CONFIG_CHANGED;
 import static android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID;
 
-import static com.android.server.connectivity.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE;
+import static com.android.networkstack.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE;
 
 import android.app.usage.NetworkStatsManager;
 import android.bluetooth.BluetoothAdapter;
@@ -81,6 +81,7 @@
 import android.net.LinkAddress;
 import android.net.LinkProperties;
 import android.net.Network;
+import android.net.NetworkCapabilities;
 import android.net.NetworkInfo;
 import android.net.TetherStatesParcel;
 import android.net.TetheredClient;
@@ -257,7 +258,7 @@
         mContext = mDeps.getContext();
         mNetd = mDeps.getINetd(mContext);
         mLooper = mDeps.getTetheringLooper();
-        mNotificationUpdater = mDeps.getNotificationUpdater(mContext);
+        mNotificationUpdater = mDeps.getNotificationUpdater(mContext, mLooper);
 
         mPublicSync = new Object();
 
@@ -307,28 +308,22 @@
                 userManager, this, mNotificationUpdater);
         mExecutor = new TetheringThreadExecutor(mHandler);
         mActiveDataSubIdListener = new ActiveDataSubIdListener(mExecutor);
+        mNetdCallback = new NetdCallback();
 
         // Load tethering configuration.
         updateConfiguration();
-        // NetdCallback should be registered after updateConfiguration() to ensure
-        // TetheringConfiguration is created.
-        mNetdCallback = new NetdCallback();
+    }
+
+    /**
+     * Start to register callbacks.
+     * Call this function when tethering is ready to handle callback events.
+     */
+    public void startStateMachineUpdaters() {
         try {
             mNetd.registerUnsolicitedEventListener(mNetdCallback);
         } catch (RemoteException e) {
             mLog.e("Unable to register netd UnsolicitedEventListener");
         }
-
-        startStateMachineUpdaters(mHandler);
-        startTrackDefaultNetwork();
-
-        final WifiManager wifiManager = getWifiManager();
-        if (wifiManager != null) {
-            wifiManager.registerSoftApCallback(mExecutor, new TetheringSoftApCallback());
-        }
-    }
-
-    private void startStateMachineUpdaters(Handler handler) {
         mCarrierConfigChange.startListening();
         mContext.getSystemService(TelephonyManager.class).listen(mActiveDataSubIdListener,
                 PhoneStateListener.LISTEN_ACTIVE_DATA_SUBSCRIPTION_ID_CHANGE);
@@ -341,7 +336,19 @@
         filter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
         filter.addAction(UserManager.ACTION_USER_RESTRICTIONS_CHANGED);
         filter.addAction(ACTION_RESTRICT_BACKGROUND_CHANGED);
-        mContext.registerReceiver(mStateReceiver, filter, null, handler);
+        mContext.registerReceiver(mStateReceiver, filter, null, mHandler);
+
+        final IntentFilter noUpstreamFilter = new IntentFilter();
+        noUpstreamFilter.addAction(TetheringNotificationUpdater.ACTION_DISABLE_TETHERING);
+        mContext.registerReceiver(
+                mStateReceiver, noUpstreamFilter, PERMISSION_MAINLINE_NETWORK_STACK, mHandler);
+
+        final WifiManager wifiManager = getWifiManager();
+        if (wifiManager != null) {
+            wifiManager.registerSoftApCallback(mExecutor, new TetheringSoftApCallback());
+        }
+
+        startTrackDefaultNetwork();
     }
 
     private class TetheringThreadExecutor implements Executor {
@@ -854,6 +861,8 @@
             } else if (action.equals(ACTION_RESTRICT_BACKGROUND_CHANGED)) {
                 mLog.log("OBSERVED data saver changed");
                 handleDataSaverChanged();
+            } else if (action.equals(TetheringNotificationUpdater.ACTION_DISABLE_TETHERING)) {
+                untetherAll();
             }
         }
 
@@ -921,8 +930,10 @@
                     case WifiManager.WIFI_AP_STATE_ENABLED:
                         enableWifiIpServingLocked(ifname, ipmode);
                         break;
-                    case WifiManager.WIFI_AP_STATE_DISABLED:
                     case WifiManager.WIFI_AP_STATE_DISABLING:
+                        // We can see this state on the way to disabled.
+                        break;
+                    case WifiManager.WIFI_AP_STATE_DISABLED:
                     case WifiManager.WIFI_AP_STATE_FAILED:
                     default:
                         disableWifiIpServingLocked(ifname, curState);
@@ -1466,7 +1477,7 @@
             if (mTetherUpstream != newUpstream) {
                 mTetherUpstream = newUpstream;
                 mUpstreamNetworkMonitor.setCurrentUpstream(mTetherUpstream);
-                reportUpstreamChanged(mTetherUpstream);
+                reportUpstreamChanged(ns);
             }
         }
 
@@ -1588,7 +1599,8 @@
             }
         }
 
-        private void handleUpstreamNetworkMonitorCallback(int arg1, Object o) {
+        @VisibleForTesting
+        void handleUpstreamNetworkMonitorCallback(int arg1, Object o) {
             if (arg1 == UpstreamNetworkMonitor.NOTIFY_LOCAL_PREFIXES) {
                 mOffload.sendOffloadExemptPrefixes((Set<IpPrefix>) o);
                 return;
@@ -1614,6 +1626,9 @@
 
             switch (arg1) {
                 case UpstreamNetworkMonitor.EVENT_ON_CAPABILITIES:
+                    if (ns.network.equals(mTetherUpstream)) {
+                        mNotificationUpdater.onUpstreamCapabilitiesChanged(ns.networkCapabilities);
+                    }
                     handleNewUpstreamNetworkState(ns);
                     break;
                 case UpstreamNetworkMonitor.EVENT_ON_LINKPROPERTIES:
@@ -1943,10 +1958,12 @@
     /** Get the latest value of the tethering entitlement check. */
     void requestLatestTetheringEntitlementResult(int type, ResultReceiver receiver,
             boolean showEntitlementUi) {
-        if (receiver != null) {
+        if (receiver == null) return;
+
+        mHandler.post(() -> {
             mEntitlementMgr.requestLatestTetheringEntitlementResult(type, receiver,
                     showEntitlementUi);
-        }
+        });
     }
 
     /** Register tethering event callback */
@@ -1997,8 +2014,10 @@
         });
     }
 
-    private void reportUpstreamChanged(Network network) {
+    private void reportUpstreamChanged(UpstreamNetworkState ns) {
         final int length = mTetheringEventCallbacks.beginBroadcast();
+        final Network network = (ns != null) ? ns.network : null;
+        final NetworkCapabilities capabilities = (ns != null) ? ns.networkCapabilities : null;
         try {
             for (int i = 0; i < length; i++) {
                 try {
@@ -2010,6 +2029,9 @@
         } finally {
             mTetheringEventCallbacks.finishBroadcast();
         }
+        // Need to notify capabilities change after upstream network changed because new network's
+        // capabilities should be checked every time.
+        mNotificationUpdater.onUpstreamCapabilitiesChanged(capabilities);
     }
 
     private void reportConfigurationChanged(TetheringConfigurationParcel config) {
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringConfiguration.java b/Tethering/src/com/android/networkstack/tethering/TetheringConfiguration.java
similarity index 99%
rename from Tethering/src/com/android/server/connectivity/tethering/TetheringConfiguration.java
rename to Tethering/src/com/android/networkstack/tethering/TetheringConfiguration.java
index 7e9e26f..aeac437 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringConfiguration.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringConfiguration.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.content.Context.TELEPHONY_SERVICE;
 import static android.net.ConnectivityManager.TYPE_ETHERNET;
@@ -33,7 +33,6 @@
 import android.text.TextUtils;
 
 import com.android.internal.annotations.VisibleForTesting;
-import com.android.networkstack.tethering.R;
 
 import java.io.PrintWriter;
 import java.util.ArrayList;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringDependencies.java b/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
similarity index 95%
rename from Tethering/src/com/android/server/connectivity/tethering/TetheringDependencies.java
rename to Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
index 0330dad..9b54b5f 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringDependencies.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import android.bluetooth.BluetoothAdapter;
 import android.content.Context;
@@ -106,8 +106,9 @@
     /**
      * Get a reference to the TetheringNotificationUpdater to be used by tethering.
      */
-    public TetheringNotificationUpdater getNotificationUpdater(@NonNull final Context ctx) {
-        return new TetheringNotificationUpdater(ctx);
+    public TetheringNotificationUpdater getNotificationUpdater(@NonNull final Context ctx,
+            @NonNull final Looper looper) {
+        return new TetheringNotificationUpdater(ctx, looper);
     }
 
     /**
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringInterfaceUtils.java b/Tethering/src/com/android/networkstack/tethering/TetheringInterfaceUtils.java
similarity index 98%
rename from Tethering/src/com/android/server/connectivity/tethering/TetheringInterfaceUtils.java
rename to Tethering/src/com/android/networkstack/tethering/TetheringInterfaceUtils.java
index 4dd6830..ff38f71 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringInterfaceUtils.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringInterfaceUtils.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import android.annotation.Nullable;
 import android.net.LinkProperties;
diff --git a/Tethering/src/com/android/networkstack/tethering/TetheringNotificationUpdater.java b/Tethering/src/com/android/networkstack/tethering/TetheringNotificationUpdater.java
new file mode 100644
index 0000000..f490cc4
--- /dev/null
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringNotificationUpdater.java
@@ -0,0 +1,448 @@
+/*
+ * 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.networkstack.tethering;
+
+import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_ROAMING;
+import static android.net.TetheringManager.TETHERING_BLUETOOTH;
+import static android.net.TetheringManager.TETHERING_USB;
+import static android.net.TetheringManager.TETHERING_WIFI;
+import static android.text.TextUtils.isEmpty;
+
+import android.app.Notification;
+import android.app.Notification.Action;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.content.Context;
+import android.content.Intent;
+import android.content.res.Configuration;
+import android.content.res.Resources;
+import android.net.NetworkCapabilities;
+import android.os.Handler;
+import android.os.Looper;
+import android.os.Message;
+import android.os.UserHandle;
+import android.provider.Settings;
+import android.telephony.SubscriptionManager;
+import android.telephony.TelephonyManager;
+import android.util.Log;
+import android.util.SparseArray;
+
+import androidx.annotation.ArrayRes;
+import androidx.annotation.DrawableRes;
+import androidx.annotation.IntDef;
+import androidx.annotation.IntRange;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * A class to display tethering-related notifications.
+ *
+ * <p>This class is not thread safe, it is intended to be used only from the tethering handler
+ * thread. However the constructor is an exception, as it is called on another thread ;
+ * therefore for thread safety all members of this class MUST either be final or initialized
+ * to their default value (0, false or null).
+ *
+ * @hide
+ */
+public class TetheringNotificationUpdater {
+    private static final String TAG = TetheringNotificationUpdater.class.getSimpleName();
+    private static final String CHANNEL_ID = "TETHERING_STATUS";
+    private static final String WIFI_DOWNSTREAM = "WIFI";
+    private static final String USB_DOWNSTREAM = "USB";
+    private static final String BLUETOOTH_DOWNSTREAM = "BT";
+    @VisibleForTesting
+    static final String ACTION_DISABLE_TETHERING =
+            "com.android.server.connectivity.tethering.DISABLE_TETHERING";
+    private static final boolean NOTIFY_DONE = true;
+    private static final boolean NO_NOTIFY = false;
+    @VisibleForTesting
+    static final int EVENT_SHOW_NO_UPSTREAM = 1;
+    // Id to update and cancel enable notification. Must be unique within the tethering app.
+    @VisibleForTesting
+    static final int ENABLE_NOTIFICATION_ID = 1000;
+    // Id to update and cancel restricted notification. Must be unique within the tethering app.
+    @VisibleForTesting
+    static final int RESTRICTED_NOTIFICATION_ID = 1001;
+    // Id to update and cancel no upstream notification. Must be unique within the tethering app.
+    @VisibleForTesting
+    static final int NO_UPSTREAM_NOTIFICATION_ID = 1002;
+    // Id to update and cancel roaming notification. Must be unique within the tethering app.
+    @VisibleForTesting
+    static final int ROAMING_NOTIFICATION_ID = 1003;
+    @VisibleForTesting
+    static final int NO_ICON_ID = 0;
+    @VisibleForTesting
+    static final int DOWNSTREAM_NONE = 0;
+    // Refer to TelephonyManager#getSimCarrierId for more details about carrier id.
+    @VisibleForTesting
+    static final int VERIZON_CARRIER_ID = 1839;
+    private final Context mContext;
+    private final NotificationManager mNotificationManager;
+    private final NotificationChannel mChannel;
+    private final Handler mHandler;
+
+    // WARNING : the constructor is called on a different thread. Thread safety therefore
+    // relies on these values being initialized to 0, false or null, and not any other value. If you
+    // need to change this, you will need to change the thread where the constructor is invoked, or
+    // to introduce synchronization.
+    // Downstream type is one of ConnectivityManager.TETHERING_* constants, 0 1 or 2.
+    // This value has to be made 1 2 and 4, and OR'd with the others.
+    private int mDownstreamTypesMask = DOWNSTREAM_NONE;
+    private boolean mNoUpstream = false;
+    private boolean mRoaming = false;
+
+    // WARNING : this value is not able to being initialized to 0 and must have volatile because
+    // telephony service is not guaranteed that is up before tethering service starts. If telephony
+    // is up later than tethering, TetheringNotificationUpdater will use incorrect and valid
+    // subscription id(0) to query resources. Therefore, initialized subscription id must be
+    // INVALID_SUBSCRIPTION_ID.
+    private volatile int mActiveDataSubId = SubscriptionManager.INVALID_SUBSCRIPTION_ID;
+
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef(value = {
+            ENABLE_NOTIFICATION_ID,
+            RESTRICTED_NOTIFICATION_ID,
+            NO_UPSTREAM_NOTIFICATION_ID,
+            ROAMING_NOTIFICATION_ID
+    })
+    @interface NotificationId {}
+
+    private static final class MccMncOverrideInfo {
+        public final String visitedMccMnc;
+        public final int homeMcc;
+        public final int homeMnc;
+        MccMncOverrideInfo(String visitedMccMnc, int mcc, int mnc) {
+            this.visitedMccMnc = visitedMccMnc;
+            this.homeMcc = mcc;
+            this.homeMnc = mnc;
+        }
+    }
+
+    private static final SparseArray<MccMncOverrideInfo> sCarrierIdToMccMnc = new SparseArray<>();
+
+    static {
+        sCarrierIdToMccMnc.put(VERIZON_CARRIER_ID, new MccMncOverrideInfo("20404", 311, 480));
+    }
+
+    public TetheringNotificationUpdater(@NonNull final Context context,
+            @NonNull final Looper looper) {
+        mContext = context;
+        mNotificationManager = (NotificationManager) context.createContextAsUser(UserHandle.ALL, 0)
+                .getSystemService(Context.NOTIFICATION_SERVICE);
+        mChannel = new NotificationChannel(
+                CHANNEL_ID,
+                context.getResources().getString(R.string.notification_channel_tethering_status),
+                NotificationManager.IMPORTANCE_LOW);
+        mNotificationManager.createNotificationChannel(mChannel);
+        mHandler = new NotificationHandler(looper);
+    }
+
+    private class NotificationHandler extends Handler {
+        NotificationHandler(Looper looper) {
+            super(looper);
+        }
+
+        @Override
+        public void handleMessage(Message msg) {
+            switch(msg.what) {
+                case EVENT_SHOW_NO_UPSTREAM:
+                    notifyTetheringNoUpstream();
+                    break;
+            }
+        }
+    }
+
+    /** Called when downstream has changed */
+    public void onDownstreamChanged(@IntRange(from = 0, to = 7) final int downstreamTypesMask) {
+        updateActiveNotifications(
+                mActiveDataSubId, downstreamTypesMask, mNoUpstream, mRoaming);
+    }
+
+    /** Called when active data subscription id changed */
+    public void onActiveDataSubscriptionIdChanged(final int subId) {
+        updateActiveNotifications(subId, mDownstreamTypesMask, mNoUpstream, mRoaming);
+    }
+
+    /** Called when upstream network capabilities changed */
+    public void onUpstreamCapabilitiesChanged(@Nullable final NetworkCapabilities capabilities) {
+        final boolean isNoUpstream = (capabilities == null);
+        final boolean isRoaming = capabilities != null
+                && !capabilities.hasCapability(NET_CAPABILITY_NOT_ROAMING);
+        updateActiveNotifications(
+                mActiveDataSubId, mDownstreamTypesMask, isNoUpstream, isRoaming);
+    }
+
+    @NonNull
+    @VisibleForTesting
+    final Handler getHandler() {
+        return mHandler;
+    }
+
+    @NonNull
+    @VisibleForTesting
+    Resources getResourcesForSubId(@NonNull final Context context, final int subId) {
+        final Resources res = SubscriptionManager.getResourcesForSubId(context, subId);
+        final TelephonyManager tm =
+                ((TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE))
+                        .createForSubscriptionId(mActiveDataSubId);
+        final int carrierId = tm.getSimCarrierId();
+        final String mccmnc = tm.getSimOperator();
+        final MccMncOverrideInfo overrideInfo = sCarrierIdToMccMnc.get(carrierId);
+        if (overrideInfo != null && overrideInfo.visitedMccMnc.equals(mccmnc)) {
+            // Re-configure MCC/MNC value to specific carrier to get right resources.
+            final Configuration config = res.getConfiguration();
+            config.mcc = overrideInfo.homeMcc;
+            config.mnc = overrideInfo.homeMnc;
+            return context.createConfigurationContext(config).getResources();
+        }
+        return res;
+    }
+
+    private void updateActiveNotifications(final int subId, final int downstreamTypes,
+            final boolean noUpstream, final boolean isRoaming) {
+        final boolean tetheringActiveChanged =
+                (downstreamTypes == DOWNSTREAM_NONE) != (mDownstreamTypesMask == DOWNSTREAM_NONE);
+        final boolean subIdChanged = subId != mActiveDataSubId;
+        final boolean downstreamChanged = downstreamTypes != mDownstreamTypesMask;
+        final boolean upstreamChanged = noUpstream != mNoUpstream;
+        final boolean roamingChanged = isRoaming != mRoaming;
+        final boolean updateAll = tetheringActiveChanged || subIdChanged;
+        mActiveDataSubId = subId;
+        mDownstreamTypesMask = downstreamTypes;
+        mNoUpstream = noUpstream;
+        mRoaming = isRoaming;
+
+        if (updateAll || downstreamChanged) updateEnableNotification();
+        if (updateAll || upstreamChanged) updateNoUpstreamNotification();
+        if (updateAll || roamingChanged) updateRoamingNotification();
+    }
+
+    private void updateEnableNotification() {
+        final boolean tetheringInactive = mDownstreamTypesMask == DOWNSTREAM_NONE;
+
+        if (tetheringInactive || setupNotification() == NO_NOTIFY) {
+            clearNotification(ENABLE_NOTIFICATION_ID);
+        }
+    }
+
+    private void updateNoUpstreamNotification() {
+        final boolean tetheringInactive = mDownstreamTypesMask == DOWNSTREAM_NONE;
+
+        if (tetheringInactive || !mNoUpstream || setupNoUpstreamNotification() == NO_NOTIFY) {
+            clearNotification(NO_UPSTREAM_NOTIFICATION_ID);
+            mHandler.removeMessages(EVENT_SHOW_NO_UPSTREAM);
+        }
+    }
+
+    private void updateRoamingNotification() {
+        final boolean tetheringInactive = mDownstreamTypesMask == DOWNSTREAM_NONE;
+
+        if (tetheringInactive || !mRoaming || setupRoamingNotification() == NO_NOTIFY) {
+            clearNotification(ROAMING_NOTIFICATION_ID);
+        }
+    }
+
+    @VisibleForTesting
+    void tetheringRestrictionLifted() {
+        clearNotification(RESTRICTED_NOTIFICATION_ID);
+    }
+
+    private void clearNotification(@NotificationId final int id) {
+        mNotificationManager.cancel(null /* tag */, id);
+    }
+
+    @VisibleForTesting
+    void notifyTetheringDisabledByRestriction() {
+        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
+        final String title = res.getString(R.string.disable_tether_notification_title);
+        final String message = res.getString(R.string.disable_tether_notification_message);
+        if (isEmpty(title) || isEmpty(message)) return;
+
+        final PendingIntent pi = PendingIntent.getActivity(
+                mContext.createContextAsUser(UserHandle.CURRENT, 0 /* flags */),
+                0 /* requestCode */,
+                new Intent(Settings.ACTION_TETHER_SETTINGS),
+                Intent.FLAG_ACTIVITY_NEW_TASK,
+                null /* options */);
+
+        showNotification(R.drawable.stat_sys_tether_general, title, message,
+                RESTRICTED_NOTIFICATION_ID, pi, new Action[0]);
+    }
+
+    private void notifyTetheringNoUpstream() {
+        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
+        final String title = res.getString(R.string.no_upstream_notification_title);
+        final String message = res.getString(R.string.no_upstream_notification_message);
+        final String disableButton =
+                res.getString(R.string.no_upstream_notification_disable_button);
+        if (isEmpty(title) || isEmpty(message) || isEmpty(disableButton)) return;
+
+        final Intent intent = new Intent(ACTION_DISABLE_TETHERING);
+        intent.setPackage(mContext.getPackageName());
+        final PendingIntent pi = PendingIntent.getBroadcast(
+                mContext.createContextAsUser(UserHandle.CURRENT, 0 /* flags */),
+                0 /* requestCode */,
+                intent,
+                0 /* flags */);
+        final Action action = new Action.Builder(NO_ICON_ID, disableButton, pi).build();
+
+        showNotification(R.drawable.stat_sys_tether_general, title, message,
+                NO_UPSTREAM_NOTIFICATION_ID, null /* pendingIntent */, action);
+    }
+
+    /**
+     * Returns the downstream types mask which convert from given string.
+     *
+     * @param types This string has to be made by "WIFI", "USB", "BT", and OR'd with the others.
+     *
+     * @return downstream types mask value.
+     */
+    @VisibleForTesting
+    @IntRange(from = 0, to = 7)
+    int getDownstreamTypesMask(@NonNull final String types) {
+        int downstreamTypesMask = DOWNSTREAM_NONE;
+        final String[] downstreams = types.split("\\|");
+        for (String downstream : downstreams) {
+            if (USB_DOWNSTREAM.equals(downstream.trim())) {
+                downstreamTypesMask |= (1 << TETHERING_USB);
+            } else if (WIFI_DOWNSTREAM.equals(downstream.trim())) {
+                downstreamTypesMask |= (1 << TETHERING_WIFI);
+            } else if (BLUETOOTH_DOWNSTREAM.equals(downstream.trim())) {
+                downstreamTypesMask |= (1 << TETHERING_BLUETOOTH);
+            }
+        }
+        return downstreamTypesMask;
+    }
+
+    /**
+     * Returns the icons {@link android.util.SparseArray} which get from given string-array resource
+     * id.
+     *
+     * @param id String-array resource id
+     *
+     * @return {@link android.util.SparseArray} with downstream types and icon id info.
+     */
+    @NonNull
+    @VisibleForTesting
+    SparseArray<Integer> getIcons(@ArrayRes int id, @NonNull Resources res) {
+        final String[] array = res.getStringArray(id);
+        final SparseArray<Integer> icons = new SparseArray<>();
+        for (String config : array) {
+            if (isEmpty(config)) continue;
+
+            final String[] elements = config.split(";");
+            if (elements.length != 2) {
+                Log.wtf(TAG,
+                        "Unexpected format in Tethering notification configuration : " + config);
+                continue;
+            }
+
+            final String[] types = elements[0].split(",");
+            for (String type : types) {
+                int mask = getDownstreamTypesMask(type);
+                if (mask == DOWNSTREAM_NONE) continue;
+                icons.put(mask, res.getIdentifier(
+                        elements[1].trim(), null /* defType */, null /* defPackage */));
+            }
+        }
+        return icons;
+    }
+
+    private boolean setupRoamingNotification() {
+        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
+        final boolean upstreamRoamingNotification =
+                res.getBoolean(R.bool.config_upstream_roaming_notification);
+
+        if (!upstreamRoamingNotification) return NO_NOTIFY;
+
+        final String title = res.getString(R.string.upstream_roaming_notification_title);
+        final String message = res.getString(R.string.upstream_roaming_notification_message);
+        if (isEmpty(title) || isEmpty(message)) return NO_NOTIFY;
+
+        final PendingIntent pi = PendingIntent.getActivity(
+                mContext.createContextAsUser(UserHandle.CURRENT, 0 /* flags */),
+                0 /* requestCode */,
+                new Intent(Settings.ACTION_TETHER_SETTINGS),
+                Intent.FLAG_ACTIVITY_NEW_TASK,
+                null /* options */);
+
+        showNotification(R.drawable.stat_sys_tether_general, title, message,
+                ROAMING_NOTIFICATION_ID, pi, new Action[0]);
+        return NOTIFY_DONE;
+    }
+
+    private boolean setupNoUpstreamNotification() {
+        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
+        final int delayToShowUpstreamNotification =
+                res.getInteger(R.integer.delay_to_show_no_upstream_after_no_backhaul);
+
+        if (delayToShowUpstreamNotification < 0) return NO_NOTIFY;
+
+        mHandler.sendMessageDelayed(mHandler.obtainMessage(EVENT_SHOW_NO_UPSTREAM),
+                delayToShowUpstreamNotification);
+        return NOTIFY_DONE;
+    }
+
+    private boolean setupNotification() {
+        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
+        final SparseArray<Integer> downstreamIcons =
+                getIcons(R.array.tethering_notification_icons, res);
+
+        final int iconId = downstreamIcons.get(mDownstreamTypesMask, NO_ICON_ID);
+        if (iconId == NO_ICON_ID) return NO_NOTIFY;
+
+        final String title = res.getString(R.string.tethering_notification_title);
+        final String message = res.getString(R.string.tethering_notification_message);
+        if (isEmpty(title) || isEmpty(message)) return NO_NOTIFY;
+
+        final PendingIntent pi = PendingIntent.getActivity(
+                mContext.createContextAsUser(UserHandle.CURRENT, 0 /* flags */),
+                0 /* requestCode */,
+                new Intent(Settings.ACTION_TETHER_SETTINGS),
+                Intent.FLAG_ACTIVITY_NEW_TASK,
+                null /* options */);
+
+        showNotification(iconId, title, message, ENABLE_NOTIFICATION_ID, pi, new Action[0]);
+        return NOTIFY_DONE;
+    }
+
+    private void showNotification(@DrawableRes final int iconId, @NonNull final String title,
+            @NonNull final String message, @NotificationId final int id, @Nullable PendingIntent pi,
+            @NonNull final Action... actions) {
+        final Notification notification =
+                new Notification.Builder(mContext, mChannel.getId())
+                        .setSmallIcon(iconId)
+                        .setContentTitle(title)
+                        .setContentText(message)
+                        .setOngoing(true)
+                        .setColor(mContext.getColor(
+                                android.R.color.system_notification_accent_color))
+                        .setVisibility(Notification.VISIBILITY_PUBLIC)
+                        .setCategory(Notification.CATEGORY_STATUS)
+                        .setContentIntent(pi)
+                        .setActions(actions)
+                        .build();
+
+        mNotificationManager.notify(null /* tag */, id, notification);
+    }
+}
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java b/Tethering/src/com/android/networkstack/tethering/TetheringService.java
similarity index 99%
rename from Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
rename to Tethering/src/com/android/networkstack/tethering/TetheringService.java
index c5329d8..3ed2115 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringService.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringService.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.net.TetheringManager.TETHER_ERROR_NO_ACCESS_TETHERING_PERMISSION;
@@ -80,6 +80,7 @@
         mContext = mDeps.getContext();
         mUserManager = (UserManager) mContext.getSystemService(Context.USER_SERVICE);
         mTethering = makeTethering(mDeps);
+        mTethering.startStateMachineUpdaters();
     }
 
     /**
diff --git a/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitor.java b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
similarity index 97%
rename from Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitor.java
rename to Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
index 7ac7f5f..25ddce4 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitor.java
+++ b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.ConnectivityManager.TYPE_BLUETOOTH;
 import static android.net.ConnectivityManager.TYPE_ETHERNET;
@@ -586,21 +586,21 @@
      */
     @VisibleForTesting
     public static NetworkCapabilities networkCapabilitiesForType(int type) {
-        final NetworkCapabilities nc = new NetworkCapabilities();
+        final NetworkCapabilities.Builder builder = new NetworkCapabilities.Builder();
 
         // Map from type to transports.
         final int notFound = -1;
         final int transport = sLegacyTypeToTransport.get(type, notFound);
         Preconditions.checkArgument(transport != notFound, "unknown legacy type: " + type);
-        nc.addTransportType(transport);
+        builder.addTransportType(transport);
 
         if (type == TYPE_MOBILE_DUN) {
-            nc.addCapability(NetworkCapabilities.NET_CAPABILITY_DUN);
+            builder.addCapability(NetworkCapabilities.NET_CAPABILITY_DUN);
             // DUN is restricted network, see NetworkCapabilities#FORCE_RESTRICTED_CAPABILITIES.
-            nc.removeCapability(NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED);
+            builder.removeCapability(NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED);
         } else {
-            nc.addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET);
+            builder.addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET);
         }
-        return nc;
+        return builder.build();
     }
 }
diff --git a/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkState.java b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkState.java
similarity index 96%
rename from Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkState.java
rename to Tethering/src/com/android/networkstack/tethering/UpstreamNetworkState.java
index 68bb837..bab9f84 100644
--- a/Tethering/src/com/android/server/connectivity/tethering/UpstreamNetworkState.java
+++ b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkState.java
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import android.net.LinkProperties;
 import android.net.Network;
diff --git a/Tethering/src/com/android/server/connectivity/tethering/TetheringNotificationUpdater.java b/Tethering/src/com/android/server/connectivity/tethering/TetheringNotificationUpdater.java
deleted file mode 100644
index 992cdd8..0000000
--- a/Tethering/src/com/android/server/connectivity/tethering/TetheringNotificationUpdater.java
+++ /dev/null
@@ -1,244 +0,0 @@
-/*
- * 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.tethering;
-
-import static android.net.TetheringManager.TETHERING_BLUETOOTH;
-import static android.net.TetheringManager.TETHERING_USB;
-import static android.net.TetheringManager.TETHERING_WIFI;
-
-import android.app.Notification;
-import android.app.NotificationChannel;
-import android.app.NotificationManager;
-import android.app.PendingIntent;
-import android.content.Context;
-import android.content.Intent;
-import android.content.res.Resources;
-import android.os.UserHandle;
-import android.provider.Settings;
-import android.telephony.SubscriptionManager;
-import android.text.TextUtils;
-import android.util.Log;
-import android.util.SparseArray;
-
-import androidx.annotation.ArrayRes;
-import androidx.annotation.DrawableRes;
-import androidx.annotation.IntDef;
-import androidx.annotation.IntRange;
-import androidx.annotation.NonNull;
-
-import com.android.internal.annotations.VisibleForTesting;
-import com.android.networkstack.tethering.R;
-
-/**
- * A class to display tethering-related notifications.
- *
- * <p>This class is not thread safe, it is intended to be used only from the tethering handler
- * thread. However the constructor is an exception, as it is called on another thread ;
- * therefore for thread safety all members of this class MUST either be final or initialized
- * to their default value (0, false or null).
- *
- * @hide
- */
-public class TetheringNotificationUpdater {
-    private static final String TAG = TetheringNotificationUpdater.class.getSimpleName();
-    private static final String CHANNEL_ID = "TETHERING_STATUS";
-    private static final String WIFI_DOWNSTREAM = "WIFI";
-    private static final String USB_DOWNSTREAM = "USB";
-    private static final String BLUETOOTH_DOWNSTREAM = "BT";
-    private static final boolean NOTIFY_DONE = true;
-    private static final boolean NO_NOTIFY = false;
-    // Id to update and cancel tethering notification. Must be unique within the tethering app.
-    private static final int ENABLE_NOTIFICATION_ID = 1000;
-    // Id to update and cancel restricted notification. Must be unique within the tethering app.
-    private static final int RESTRICTED_NOTIFICATION_ID = 1001;
-    @VisibleForTesting
-    static final int NO_ICON_ID = 0;
-    @VisibleForTesting
-    static final int DOWNSTREAM_NONE = 0;
-    private final Context mContext;
-    private final NotificationManager mNotificationManager;
-    private final NotificationChannel mChannel;
-
-    // WARNING : the constructor is called on a different thread. Thread safety therefore
-    // relies on this value being initialized to 0, and not any other value. If you need
-    // to change this, you will need to change the thread where the constructor is invoked,
-    // or to introduce synchronization.
-    // Downstream type is one of ConnectivityManager.TETHERING_* constants, 0 1 or 2.
-    // This value has to be made 1 2 and 4, and OR'd with the others.
-    private int mDownstreamTypesMask = DOWNSTREAM_NONE;
-
-    // WARNING : this value is not able to being initialized to 0 and must have volatile because
-    // telephony service is not guaranteed that is up before tethering service starts. If telephony
-    // is up later than tethering, TetheringNotificationUpdater will use incorrect and valid
-    // subscription id(0) to query resources. Therefore, initialized subscription id must be
-    // INVALID_SUBSCRIPTION_ID.
-    private volatile int mActiveDataSubId = SubscriptionManager.INVALID_SUBSCRIPTION_ID;
-
-    @IntDef({ENABLE_NOTIFICATION_ID, RESTRICTED_NOTIFICATION_ID})
-    @interface NotificationId {}
-
-    public TetheringNotificationUpdater(@NonNull final Context context) {
-        mContext = context;
-        mNotificationManager = (NotificationManager) context.createContextAsUser(UserHandle.ALL, 0)
-                .getSystemService(Context.NOTIFICATION_SERVICE);
-        mChannel = new NotificationChannel(
-                CHANNEL_ID,
-                context.getResources().getString(R.string.notification_channel_tethering_status),
-                NotificationManager.IMPORTANCE_LOW);
-        mNotificationManager.createNotificationChannel(mChannel);
-    }
-
-    /** Called when downstream has changed */
-    public void onDownstreamChanged(@IntRange(from = 0, to = 7) final int downstreamTypesMask) {
-        if (mDownstreamTypesMask == downstreamTypesMask) return;
-        mDownstreamTypesMask = downstreamTypesMask;
-        updateEnableNotification();
-    }
-
-    /** Called when active data subscription id changed */
-    public void onActiveDataSubscriptionIdChanged(final int subId) {
-        if (mActiveDataSubId == subId) return;
-        mActiveDataSubId = subId;
-        updateEnableNotification();
-    }
-
-    @VisibleForTesting
-    Resources getResourcesForSubId(@NonNull final Context c, final int subId) {
-        return SubscriptionManager.getResourcesForSubId(c, subId);
-    }
-
-    private void updateEnableNotification() {
-        final boolean tetheringInactive = mDownstreamTypesMask <= DOWNSTREAM_NONE;
-
-        if (tetheringInactive || setupNotification() == NO_NOTIFY) {
-            clearNotification(ENABLE_NOTIFICATION_ID);
-        }
-    }
-
-    @VisibleForTesting
-    void tetheringRestrictionLifted() {
-        clearNotification(RESTRICTED_NOTIFICATION_ID);
-    }
-
-    private void clearNotification(@NotificationId final int id) {
-        mNotificationManager.cancel(null /* tag */, id);
-    }
-
-    @VisibleForTesting
-    void notifyTetheringDisabledByRestriction() {
-        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
-        final String title = res.getString(R.string.disable_tether_notification_title);
-        final String message = res.getString(R.string.disable_tether_notification_message);
-
-        showNotification(R.drawable.stat_sys_tether_general, title, message,
-                RESTRICTED_NOTIFICATION_ID);
-    }
-
-    /**
-     * Returns the downstream types mask which convert from given string.
-     *
-     * @param types This string has to be made by "WIFI", "USB", "BT", and OR'd with the others.
-     *
-     * @return downstream types mask value.
-     */
-    @VisibleForTesting
-    @IntRange(from = 0, to = 7)
-    int getDownstreamTypesMask(@NonNull final String types) {
-        int downstreamTypesMask = DOWNSTREAM_NONE;
-        final String[] downstreams = types.split("\\|");
-        for (String downstream : downstreams) {
-            if (USB_DOWNSTREAM.equals(downstream.trim())) {
-                downstreamTypesMask |= (1 << TETHERING_USB);
-            } else if (WIFI_DOWNSTREAM.equals(downstream.trim())) {
-                downstreamTypesMask |= (1 << TETHERING_WIFI);
-            } else if (BLUETOOTH_DOWNSTREAM.equals(downstream.trim())) {
-                downstreamTypesMask |= (1 << TETHERING_BLUETOOTH);
-            }
-        }
-        return downstreamTypesMask;
-    }
-
-    /**
-     * Returns the icons {@link android.util.SparseArray} which get from given string-array resource
-     * id.
-     *
-     * @param id String-array resource id
-     *
-     * @return {@link android.util.SparseArray} with downstream types and icon id info.
-     */
-    @VisibleForTesting
-    SparseArray<Integer> getIcons(@ArrayRes int id, @NonNull Resources res) {
-        final String[] array = res.getStringArray(id);
-        final SparseArray<Integer> icons = new SparseArray<>();
-        for (String config : array) {
-            if (TextUtils.isEmpty(config)) continue;
-
-            final String[] elements = config.split(";");
-            if (elements.length != 2) {
-                Log.wtf(TAG,
-                        "Unexpected format in Tethering notification configuration : " + config);
-                continue;
-            }
-
-            final String[] types = elements[0].split(",");
-            for (String type : types) {
-                int mask = getDownstreamTypesMask(type);
-                if (mask == DOWNSTREAM_NONE) continue;
-                icons.put(mask, res.getIdentifier(
-                        elements[1].trim(), null /* defType */, null /* defPackage */));
-            }
-        }
-        return icons;
-    }
-
-    private boolean setupNotification() {
-        final Resources res = getResourcesForSubId(mContext, mActiveDataSubId);
-        final SparseArray<Integer> downstreamIcons =
-                getIcons(R.array.tethering_notification_icons, res);
-
-        final int iconId = downstreamIcons.get(mDownstreamTypesMask, NO_ICON_ID);
-        if (iconId == NO_ICON_ID) return NO_NOTIFY;
-
-        final String title = res.getString(R.string.tethering_notification_title);
-        final String message = res.getString(R.string.tethering_notification_message);
-
-        showNotification(iconId, title, message, ENABLE_NOTIFICATION_ID);
-        return NOTIFY_DONE;
-    }
-
-    private void showNotification(@DrawableRes final int iconId, @NonNull final String title,
-            @NonNull final String message, @NotificationId final int id) {
-        final Intent intent = new Intent(Settings.ACTION_TETHER_SETTINGS);
-        final PendingIntent pi = PendingIntent.getActivity(
-                mContext.createContextAsUser(UserHandle.CURRENT, 0),
-                0 /* requestCode */, intent, 0 /* flags */, null /* options */);
-        final Notification notification =
-                new Notification.Builder(mContext, mChannel.getId())
-                        .setSmallIcon(iconId)
-                        .setContentTitle(title)
-                        .setContentText(message)
-                        .setOngoing(true)
-                        .setColor(mContext.getColor(
-                                android.R.color.system_notification_accent_color))
-                        .setVisibility(Notification.VISIBILITY_PUBLIC)
-                        .setCategory(Notification.CATEGORY_STATUS)
-                        .setContentIntent(pi)
-                        .build();
-
-        mNotificationManager.notify(null /* tag */, id, notification);
-    }
-}
diff --git a/Tethering/tests/integration/Android.bp b/Tethering/tests/integration/Android.bp
new file mode 100644
index 0000000..6b751af
--- /dev/null
+++ b/Tethering/tests/integration/Android.bp
@@ -0,0 +1,85 @@
+//
+// 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.
+//
+java_defaults {
+    name: "TetheringIntegrationTestsDefaults",
+    srcs: [
+        "src/**/*.java",
+        "src/**/*.kt",
+    ],
+    static_libs: [
+        "NetworkStackApiStableLib",
+        "androidx.test.rules",
+        "frameworks-base-testutils",
+        "mockito-target-extended-minus-junit4",
+        "net-tests-utils",
+        "testables",
+    ],
+    libs: [
+        "android.test.runner",
+        "android.test.base",
+        "android.test.mock",
+    ],
+    jni_libs: [
+        // For mockito extended
+        "libdexmakerjvmtiagent",
+        "libstaticjvmtiagent",
+    ],
+    jarjar_rules: ":NetworkStackJarJarRules",
+}
+
+android_library {
+    name: "TetheringIntegrationTestsLib",
+    platform_apis: true,
+    defaults: ["TetheringIntegrationTestsDefaults"],
+    visibility: ["//cts/tests/tests/tethering"]
+}
+
+android_test {
+    name: "TetheringIntegrationTests",
+    platform_apis: true,
+    defaults: ["TetheringIntegrationTestsDefaults"],
+    test_suites: [
+        "device-tests",
+        "mts",
+    ],
+    compile_multilib: "both",
+}
+
+// Special version of the tethering tests that includes all tests necessary for code coverage
+// purposes. This is currently the union of TetheringTests, TetheringIntegrationTests and
+// NetworkStackTests.
+android_test {
+    name: "TetheringCoverageTests",
+    certificate: "platform",
+    platform_apis: true,
+    test_suites: ["device-tests", "mts"],
+    test_config: "AndroidTest_Coverage.xml",
+    defaults: ["libnetworkstackutilsjni_deps"],
+    static_libs: [
+        "NetworkStackTestsLib",
+        "TetheringTestsLib",
+        "TetheringIntegrationTestsLib",
+    ],
+    jni_libs: [
+        // For mockito extended
+        "libdexmakerjvmtiagent",
+        "libstaticjvmtiagent",
+        // For NetworkStackUtils included in NetworkStackBase
+        "libnetworkstackutilsjni",
+    ],
+    compile_multilib: "both",
+    manifest: "AndroidManifest_coverage.xml",
+}
\ No newline at end of file
diff --git a/Tethering/tests/integration/AndroidManifest.xml b/Tethering/tests/integration/AndroidManifest.xml
new file mode 100644
index 0000000..fddfaad
--- /dev/null
+++ b/Tethering/tests/integration/AndroidManifest.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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.
+-->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          package="com.android.networkstack.tethering.tests.integration">
+
+    <uses-permission android:name="android.permission.INTERNET"/>
+
+    <application android:debuggable="true">
+        <uses-library android:name="android.test.runner" />
+    </application>
+    <instrumentation android:name="androidx.test.runner.AndroidJUnitRunner"
+        android:targetPackage="com.android.networkstack.tethering.tests.integration"
+        android:label="Tethering integration tests">
+    </instrumentation>
+</manifest>
diff --git a/Tethering/tests/integration/AndroidManifest_coverage.xml b/Tethering/tests/integration/AndroidManifest_coverage.xml
new file mode 100644
index 0000000..06de00d
--- /dev/null
+++ b/Tethering/tests/integration/AndroidManifest_coverage.xml
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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.
+-->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          xmlns:tools="http://schemas.android.com/tools"
+          package="com.android.networkstack.tethering.tests.coverage">
+
+    <application tools:replace="android:label"
+                 android:debuggable="true"
+                 android:label="Tethering coverage tests">
+        <uses-library android:name="android.test.runner" />
+    </application>
+    <instrumentation android:name="androidx.test.runner.AndroidJUnitRunner"
+                     android:targetPackage="com.android.networkstack.tethering.tests.coverage"
+                     android:label="Tethering coverage tests">
+    </instrumentation>
+</manifest>
diff --git a/Tethering/tests/integration/AndroidTest_Coverage.xml b/Tethering/tests/integration/AndroidTest_Coverage.xml
new file mode 100644
index 0000000..3def209
--- /dev/null
+++ b/Tethering/tests/integration/AndroidTest_Coverage.xml
@@ -0,0 +1,12 @@
+<configuration description="Runs coverage tests for Tethering">
+    <target_preparer class="com.android.tradefed.targetprep.TestAppInstallSetup">
+        <option name="test-file-name" value="TetheringCoverageTests.apk" />
+    </target_preparer>
+
+    <option name="test-tag" value="TetheringCoverageTests" />
+    <test class="com.android.tradefed.testtype.AndroidJUnitTest" >
+        <option name="package" value="com.android.networkstack.tethering.tests.coverage" />
+        <option name="runner" value="androidx.test.runner.AndroidJUnitRunner" />
+        <option name="hidden-api-checks" value="false"/>
+    </test>
+</configuration>
\ No newline at end of file
diff --git a/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java b/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java
new file mode 100644
index 0000000..4bac9da
--- /dev/null
+++ b/Tethering/tests/integration/src/android/net/EthernetTetheringTest.java
@@ -0,0 +1,550 @@
+/*
+ * 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 android.net;
+
+import static android.Manifest.permission.MANAGE_TEST_NETWORKS;
+import static android.Manifest.permission.NETWORK_SETTINGS;
+import static android.Manifest.permission.TETHER_PRIVILEGED;
+import static android.net.TetheringManager.TETHERING_ETHERNET;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.junit.Assume.assumeFalse;
+import static org.junit.Assume.assumeTrue;
+
+import android.app.UiAutomation;
+import android.content.Context;
+import android.net.EthernetManager.TetheredInterfaceCallback;
+import android.net.EthernetManager.TetheredInterfaceRequest;
+import android.net.TetheringManager.StartTetheringCallback;
+import android.net.TetheringManager.TetheringEventCallback;
+import android.net.TetheringManager.TetheringRequest;
+import android.net.dhcp.DhcpAckPacket;
+import android.net.dhcp.DhcpOfferPacket;
+import android.net.dhcp.DhcpPacket;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.SystemClock;
+import android.system.Os;
+import android.util.Log;
+
+import androidx.test.InstrumentationRegistry;
+import androidx.test.filters.MediumTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import com.android.testutils.HandlerUtilsKt;
+import com.android.testutils.TapPacketReader;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.io.FileDescriptor;
+import java.net.Inet4Address;
+import java.net.InterfaceAddress;
+import java.net.NetworkInterface;
+import java.net.SocketException;
+import java.nio.ByteBuffer;
+import java.util.Collection;
+import java.util.List;
+import java.util.Random;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+@RunWith(AndroidJUnit4.class)
+@MediumTest
+public class EthernetTetheringTest {
+
+    private static final String TAG = EthernetTetheringTest.class.getSimpleName();
+    private static final int TIMEOUT_MS = 1000;
+    private static final int PACKET_READ_TIMEOUT_MS = 100;
+    private static final int DHCP_DISCOVER_ATTEMPTS = 10;
+    private static final byte[] DHCP_REQUESTED_PARAMS = new byte[] {
+            DhcpPacket.DHCP_SUBNET_MASK,
+            DhcpPacket.DHCP_ROUTER,
+            DhcpPacket.DHCP_DNS_SERVER,
+            DhcpPacket.DHCP_LEASE_TIME,
+    };
+    private static final String DHCP_HOSTNAME = "testhostname";
+
+    private final Context mContext = InstrumentationRegistry.getContext();
+    private final EthernetManager mEm = mContext.getSystemService(EthernetManager.class);
+    private final TetheringManager mTm = mContext.getSystemService(TetheringManager.class);
+
+    private TestNetworkInterface mTestIface;
+    private HandlerThread mHandlerThread;
+    private Handler mHandler;
+    private TapPacketReader mTapPacketReader;
+
+    private TetheredInterfaceRequester mTetheredInterfaceRequester;
+    private MyTetheringEventCallback mTetheringEventCallback;
+
+    private UiAutomation mUiAutomation =
+            InstrumentationRegistry.getInstrumentation().getUiAutomation();
+
+    @Before
+    public void setUp() throws Exception {
+        mHandlerThread = new HandlerThread(getClass().getSimpleName());
+        mHandlerThread.start();
+        mHandler = new Handler(mHandlerThread.getLooper());
+        mTetheredInterfaceRequester = new TetheredInterfaceRequester(mHandler, mEm);
+        // Needed to create a TestNetworkInterface, to call requestTetheredInterface, and to receive
+        // tethered client callbacks.
+        mUiAutomation.adoptShellPermissionIdentity(
+                MANAGE_TEST_NETWORKS, NETWORK_SETTINGS, TETHER_PRIVILEGED);
+    }
+
+    private void cleanUp() throws Exception {
+        mTm.stopTethering(TETHERING_ETHERNET);
+        if (mTetheringEventCallback != null) {
+            mTetheringEventCallback.awaitInterfaceUntethered();
+            mTetheringEventCallback.unregister();
+            mTetheringEventCallback = null;
+        }
+        if (mTapPacketReader != null) {
+            TapPacketReader reader = mTapPacketReader;
+            mHandler.post(() -> reader.stop());
+            mTapPacketReader = null;
+        }
+        mHandlerThread.quitSafely();
+        mTetheredInterfaceRequester.release();
+        mEm.setIncludeTestInterfaces(false);
+        maybeDeleteTestInterface();
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        try {
+            cleanUp();
+        } finally {
+            mUiAutomation.dropShellPermissionIdentity();
+        }
+    }
+
+    @Test
+    public void testVirtualEthernetAlreadyExists() throws Exception {
+        // This test requires manipulating packets. Skip if there is a physical Ethernet connected.
+        assumeFalse(mEm.isAvailable());
+
+        mTestIface = createTestInterface();
+        // This must be done now because as soon as setIncludeTestInterfaces(true) is called, the
+        // interface will be placed in client mode, which will delete the link-local address.
+        // At that point NetworkInterface.getByName() will cease to work on the interface, because
+        // starting in R NetworkInterface can no longer see interfaces without IP addresses.
+        int mtu = getMTU(mTestIface);
+
+        Log.d(TAG, "Including test interfaces");
+        mEm.setIncludeTestInterfaces(true);
+
+        final String iface = mTetheredInterfaceRequester.getInterface();
+        assertEquals("TetheredInterfaceCallback for unexpected interface",
+                mTestIface.getInterfaceName(), iface);
+
+        checkVirtualEthernet(mTestIface, mtu);
+    }
+
+    @Test
+    public void testVirtualEthernet() throws Exception {
+        // This test requires manipulating packets. Skip if there is a physical Ethernet connected.
+        assumeFalse(mEm.isAvailable());
+
+        CompletableFuture<String> futureIface = mTetheredInterfaceRequester.requestInterface();
+
+        mEm.setIncludeTestInterfaces(true);
+
+        mTestIface = createTestInterface();
+
+        final String iface = futureIface.get(TIMEOUT_MS, TimeUnit.MILLISECONDS);
+        assertEquals("TetheredInterfaceCallback for unexpected interface",
+                mTestIface.getInterfaceName(), iface);
+
+        checkVirtualEthernet(mTestIface, getMTU(mTestIface));
+    }
+
+    @Test
+    public void testStaticIpv4() throws Exception {
+        assumeFalse(mEm.isAvailable());
+
+        mEm.setIncludeTestInterfaces(true);
+
+        mTestIface = createTestInterface();
+
+        final String iface = mTetheredInterfaceRequester.getInterface();
+        assertEquals("TetheredInterfaceCallback for unexpected interface",
+                mTestIface.getInterfaceName(), iface);
+
+        assertInvalidStaticIpv4Request(iface, null, null);
+        assertInvalidStaticIpv4Request(iface, "2001:db8::1/64", "2001:db8:2::/64");
+        assertInvalidStaticIpv4Request(iface, "192.0.2.2/28", "2001:db8:2::/28");
+        assertInvalidStaticIpv4Request(iface, "2001:db8:2::/28", "192.0.2.2/28");
+        assertInvalidStaticIpv4Request(iface, "192.0.2.2/28", null);
+        assertInvalidStaticIpv4Request(iface, null, "192.0.2.2/28");
+        assertInvalidStaticIpv4Request(iface, "192.0.2.3/27", "192.0.2.2/28");
+
+        final String localAddr = "192.0.2.3/28";
+        final String clientAddr = "192.0.2.2/28";
+        mTetheringEventCallback = enableEthernetTethering(iface,
+                requestWithStaticIpv4(localAddr, clientAddr));
+
+        mTetheringEventCallback.awaitInterfaceTethered();
+        assertInterfaceHasIpAddress(iface, localAddr);
+
+        byte[] client1 = MacAddress.fromString("1:2:3:4:5:6").toByteArray();
+        byte[] client2 = MacAddress.fromString("a:b:c:d:e:f").toByteArray();
+
+        FileDescriptor fd = mTestIface.getFileDescriptor().getFileDescriptor();
+        mTapPacketReader = makePacketReader(fd, getMTU(mTestIface));
+        DhcpResults dhcpResults = runDhcp(fd, client1);
+        assertEquals(new LinkAddress(clientAddr), dhcpResults.ipAddress);
+
+        try {
+            runDhcp(fd, client2);
+            fail("Only one client should get an IP address");
+        } catch (TimeoutException expected) { }
+
+    }
+
+    @Test
+    public void testPhysicalEthernet() throws Exception {
+        assumeTrue(mEm.isAvailable());
+
+        // Get an interface to use.
+        final String iface = mTetheredInterfaceRequester.getInterface();
+
+        // Enable Ethernet tethering and check that it starts.
+        mTetheringEventCallback = enableEthernetTethering(iface);
+
+        // There is nothing more we can do on a physical interface without connecting an actual
+        // client, which is not possible in this test.
+    }
+
+    private static final class MyTetheringEventCallback implements TetheringEventCallback {
+        private final TetheringManager mTm;
+        private final CountDownLatch mTetheringStartedLatch = new CountDownLatch(1);
+        private final CountDownLatch mTetheringStoppedLatch = new CountDownLatch(1);
+        private final CountDownLatch mClientConnectedLatch = new CountDownLatch(1);
+        private final String mIface;
+
+        private volatile boolean mInterfaceWasTethered = false;
+        private volatile boolean mUnregistered = false;
+        private volatile Collection<TetheredClient> mClients = null;
+
+        MyTetheringEventCallback(TetheringManager tm, String iface) {
+            mTm = tm;
+            mIface = iface;
+        }
+
+        public void unregister() {
+            mTm.unregisterTetheringEventCallback(this);
+            mUnregistered = true;
+        }
+
+        @Override
+        public void onTetheredInterfacesChanged(List<String> interfaces) {
+            // Ignore stale callbacks registered by previous test cases.
+            if (mUnregistered) return;
+
+            final boolean wasTethered = mTetheringStartedLatch.getCount() == 0;
+            if (!mInterfaceWasTethered && (mIface == null || interfaces.contains(mIface))) {
+                // This interface is being tethered for the first time.
+                Log.d(TAG, "Tethering started: " + interfaces);
+                mInterfaceWasTethered = true;
+                mTetheringStartedLatch.countDown();
+            } else if (mInterfaceWasTethered && !interfaces.contains(mIface)) {
+                Log.d(TAG, "Tethering stopped: " + interfaces);
+                mTetheringStoppedLatch.countDown();
+            }
+        }
+
+        public void awaitInterfaceTethered() throws Exception {
+            assertTrue("Ethernet not tethered after " + TIMEOUT_MS + "ms",
+                    mTetheringStartedLatch.await(TIMEOUT_MS, TimeUnit.MILLISECONDS));
+        }
+
+        public void awaitInterfaceUntethered() throws Exception {
+            // Don't block teardown if the interface was never tethered.
+            // This is racy because the interface might become tethered right after this check, but
+            // that can only happen in tearDown if startTethering timed out, which likely means
+            // the test has already failed.
+            if (!mInterfaceWasTethered) return;
+
+            assertTrue(mIface + " not untethered after " + TIMEOUT_MS + "ms",
+                    mTetheringStoppedLatch.await(TIMEOUT_MS, TimeUnit.MILLISECONDS));
+        }
+
+        @Override
+        public void onError(String ifName, int error) {
+            // Ignore stale callbacks registered by previous test cases.
+            if (mUnregistered) return;
+
+            fail("TetheringEventCallback got error:" + error + " on iface " + ifName);
+        }
+
+        @Override
+        public void onClientsChanged(Collection<TetheredClient> clients) {
+            // Ignore stale callbacks registered by previous test cases.
+            if (mUnregistered) return;
+
+            Log.d(TAG, "Got clients changed: " + clients);
+            mClients = clients;
+            if (clients.size() > 0) {
+                mClientConnectedLatch.countDown();
+            }
+        }
+
+        public Collection<TetheredClient> awaitClientConnected() throws Exception {
+            assertTrue("Did not receive client connected callback after " + TIMEOUT_MS + "ms",
+                    mClientConnectedLatch.await(TIMEOUT_MS, TimeUnit.MILLISECONDS));
+            return mClients;
+        }
+    }
+
+    private MyTetheringEventCallback enableEthernetTethering(String iface,
+            TetheringRequest request) throws Exception {
+        MyTetheringEventCallback callback = new MyTetheringEventCallback(mTm, iface);
+        mTm.registerTetheringEventCallback(mHandler::post, callback);
+
+        StartTetheringCallback startTetheringCallback = new StartTetheringCallback() {
+            @Override
+            public void onTetheringFailed(int resultCode) {
+                fail("Unexpectedly got onTetheringFailed");
+            }
+        };
+        Log.d(TAG, "Starting Ethernet tethering");
+        mTm.startTethering(request, mHandler::post /* executor */,  startTetheringCallback);
+        callback.awaitInterfaceTethered();
+        return callback;
+    }
+
+    private MyTetheringEventCallback enableEthernetTethering(String iface) throws Exception {
+        return enableEthernetTethering(iface,
+                new TetheringRequest.Builder(TETHERING_ETHERNET).build());
+    }
+
+    private int getMTU(TestNetworkInterface iface) throws SocketException {
+        NetworkInterface nif = NetworkInterface.getByName(iface.getInterfaceName());
+        assertNotNull("Can't get NetworkInterface object for " + iface.getInterfaceName(), nif);
+        return nif.getMTU();
+    }
+
+    private TapPacketReader makePacketReader(FileDescriptor fd, int mtu) {
+        final TapPacketReader reader = new TapPacketReader(mHandler, fd, mtu);
+        mHandler.post(() -> reader.start());
+        HandlerUtilsKt.waitForIdle(mHandler, TIMEOUT_MS);
+        return reader;
+    }
+
+    private void checkVirtualEthernet(TestNetworkInterface iface, int mtu) throws Exception {
+        FileDescriptor fd = iface.getFileDescriptor().getFileDescriptor();
+        mTapPacketReader = makePacketReader(fd, mtu);
+        mTetheringEventCallback = enableEthernetTethering(iface.getInterfaceName());
+        checkTetheredClientCallbacks(fd);
+    }
+
+    private DhcpResults runDhcp(FileDescriptor fd, byte[] clientMacAddr) throws Exception {
+        // We have to retransmit DHCP requests because IpServer declares itself to be ready before
+        // its DhcpServer is actually started. TODO: fix this race and remove this loop.
+        DhcpPacket offerPacket = null;
+        for (int i = 0; i < DHCP_DISCOVER_ATTEMPTS; i++) {
+            Log.d(TAG, "Sending DHCP discover");
+            sendDhcpDiscover(fd, clientMacAddr);
+            offerPacket = getNextDhcpPacket();
+            if (offerPacket instanceof DhcpOfferPacket) break;
+        }
+        if (!(offerPacket instanceof DhcpOfferPacket)) {
+            throw new TimeoutException("No DHCPOFFER received on interface within timeout");
+        }
+
+        sendDhcpRequest(fd, offerPacket, clientMacAddr);
+        DhcpPacket ackPacket = getNextDhcpPacket();
+        if (!(ackPacket instanceof DhcpAckPacket)) {
+            throw new TimeoutException("No DHCPACK received on interface within timeout");
+        }
+
+        return ackPacket.toDhcpResults();
+    }
+
+    private void checkTetheredClientCallbacks(FileDescriptor fd) throws Exception {
+        // Create a fake client.
+        byte[] clientMacAddr = new byte[6];
+        new Random().nextBytes(clientMacAddr);
+
+        DhcpResults dhcpResults = runDhcp(fd, clientMacAddr);
+
+        final Collection<TetheredClient> clients = mTetheringEventCallback.awaitClientConnected();
+        assertEquals(1, clients.size());
+        final TetheredClient client = clients.iterator().next();
+
+        // Check the MAC address.
+        assertEquals(MacAddress.fromBytes(clientMacAddr), client.getMacAddress());
+        assertEquals(TETHERING_ETHERNET, client.getTetheringType());
+
+        // Check the hostname.
+        assertEquals(1, client.getAddresses().size());
+        TetheredClient.AddressInfo info = client.getAddresses().get(0);
+        assertEquals(DHCP_HOSTNAME, info.getHostname());
+
+        // Check the address is the one that was handed out in the DHCP ACK.
+        assertLinkAddressMatches(dhcpResults.ipAddress, info.getAddress());
+
+        // Check that the lifetime is correct +/- 10s.
+        final long now = SystemClock.elapsedRealtime();
+        final long actualLeaseDuration = (info.getAddress().getExpirationTime() - now) / 1000;
+        final String msg = String.format("IP address should have lifetime of %d, got %d",
+                dhcpResults.leaseDuration, actualLeaseDuration);
+        assertTrue(msg, Math.abs(dhcpResults.leaseDuration - actualLeaseDuration) < 10);
+    }
+
+    private DhcpPacket getNextDhcpPacket() throws ParseException {
+        byte[] packet;
+        while ((packet = mTapPacketReader.popPacket(PACKET_READ_TIMEOUT_MS)) != null) {
+            try {
+                return DhcpPacket.decodeFullPacket(packet, packet.length, DhcpPacket.ENCAP_L2);
+            } catch (DhcpPacket.ParseException e) {
+                // Not a DHCP packet. Continue.
+            }
+        }
+        return null;
+    }
+
+    private static final class TetheredInterfaceRequester implements TetheredInterfaceCallback {
+        private final CountDownLatch mInterfaceAvailableLatch = new CountDownLatch(1);
+        private final Handler mHandler;
+        private final EthernetManager mEm;
+
+        private TetheredInterfaceRequest mRequest;
+        private final CompletableFuture<String> mFuture = new CompletableFuture<>();
+
+        TetheredInterfaceRequester(Handler handler, EthernetManager em) {
+            mHandler = handler;
+            mEm = em;
+        }
+
+        @Override
+        public void onAvailable(String iface) {
+            Log.d(TAG, "Ethernet interface available: " + iface);
+            mFuture.complete(iface);
+        }
+
+        @Override
+        public void onUnavailable() {
+            mFuture.completeExceptionally(new IllegalStateException("onUnavailable received"));
+        }
+
+        public CompletableFuture<String> requestInterface() {
+            assertNull("BUG: more than one tethered interface request", mRequest);
+            Log.d(TAG, "Requesting tethered interface");
+            mRequest = mEm.requestTetheredInterface(mHandler::post, this);
+            return mFuture;
+        }
+
+        public String getInterface() throws Exception {
+            return requestInterface().get(TIMEOUT_MS, TimeUnit.MILLISECONDS);
+        }
+
+        public void release() {
+            if (mRequest != null) {
+                mFuture.obtrudeException(new IllegalStateException("Request already released"));
+                mRequest.release();
+                mRequest = null;
+            }
+        }
+    }
+
+    private void sendDhcpDiscover(FileDescriptor fd, byte[] macAddress) throws Exception {
+        ByteBuffer packet = DhcpPacket.buildDiscoverPacket(DhcpPacket.ENCAP_L2,
+                new Random().nextInt() /* transactionId */, (short) 0 /* secs */,
+                macAddress,  false /* unicast */, DHCP_REQUESTED_PARAMS,
+                false /* rapid commit */,  DHCP_HOSTNAME);
+        sendPacket(fd, packet);
+    }
+
+    private void sendDhcpRequest(FileDescriptor fd, DhcpPacket offerPacket, byte[] macAddress)
+            throws Exception {
+        DhcpResults results = offerPacket.toDhcpResults();
+        Inet4Address clientIp = (Inet4Address) results.ipAddress.getAddress();
+        Inet4Address serverIdentifier = results.serverAddress;
+        ByteBuffer packet = DhcpPacket.buildRequestPacket(DhcpPacket.ENCAP_L2,
+                0 /* transactionId */, (short) 0 /* secs */, DhcpPacket.INADDR_ANY /* clientIp */,
+                false /* broadcast */, macAddress, clientIp /* requestedIpAddress */,
+                serverIdentifier, DHCP_REQUESTED_PARAMS, DHCP_HOSTNAME);
+        sendPacket(fd, packet);
+    }
+
+    private void sendPacket(FileDescriptor fd, ByteBuffer packet) throws Exception {
+        assertNotNull("Only tests on virtual interfaces can send packets", fd);
+        Os.write(fd, packet);
+    }
+
+    public void assertLinkAddressMatches(LinkAddress l1, LinkAddress l2) {
+        // Check all fields except the deprecation and expiry times.
+        String msg = String.format("LinkAddresses do not match. expected: %s actual: %s", l1, l2);
+        assertTrue(msg, l1.isSameAddressAs(l2));
+        assertEquals("LinkAddress flags do not match", l1.getFlags(), l2.getFlags());
+        assertEquals("LinkAddress scope does not match", l1.getScope(), l2.getScope());
+    }
+
+    private TetheringRequest requestWithStaticIpv4(String local, String client) {
+        LinkAddress localAddr = local == null ? null : new LinkAddress(local);
+        LinkAddress clientAddr = client == null ? null : new LinkAddress(client);
+        return new TetheringRequest.Builder(TETHERING_ETHERNET)
+                .setStaticIpv4Addresses(localAddr, clientAddr).build();
+    }
+
+    private void assertInvalidStaticIpv4Request(String iface, String local, String client)
+            throws Exception {
+        try {
+            enableEthernetTethering(iface, requestWithStaticIpv4(local, client));
+            fail("Unexpectedly accepted invalid IPv4 configuration: " + local + ", " + client);
+        } catch (IllegalArgumentException | NullPointerException expected) { }
+    }
+
+    private void assertInterfaceHasIpAddress(String iface, String expected) throws Exception {
+        LinkAddress expectedAddr = new LinkAddress(expected);
+        NetworkInterface nif = NetworkInterface.getByName(iface);
+        for (InterfaceAddress ia : nif.getInterfaceAddresses()) {
+            final LinkAddress addr = new LinkAddress(ia.getAddress(), ia.getNetworkPrefixLength());
+            if (expectedAddr.equals(addr)) {
+                return;
+            }
+        }
+        fail("Expected " + iface + " to have IP address " + expected + ", found "
+                + nif.getInterfaceAddresses());
+    }
+
+    private TestNetworkInterface createTestInterface() throws Exception {
+        TestNetworkManager tnm = mContext.getSystemService(TestNetworkManager.class);
+        TestNetworkInterface iface = tnm.createTapInterface();
+        Log.d(TAG, "Created test interface " + iface.getInterfaceName());
+        assertNotNull(NetworkInterface.getByName(iface.getInterfaceName()));
+        return iface;
+    }
+
+    private void maybeDeleteTestInterface() throws Exception {
+        if (mTestIface != null) {
+            mTestIface.getFileDescriptor().close();
+            Log.d(TAG, "Deleted test interface " + mTestIface.getInterfaceName());
+            mTestIface = null;
+        }
+    }
+}
diff --git a/Tethering/tests/unit/Android.bp b/Tethering/tests/unit/Android.bp
index ddc095f..499ac0e 100644
--- a/Tethering/tests/unit/Android.bp
+++ b/Tethering/tests/unit/Android.bp
@@ -14,36 +14,30 @@
 // limitations under the License.
 //
 
-android_test {
-    name: "TetheringTests",
-    certificate: "platform",
+java_defaults {
+    name: "TetheringTestsDefaults",
     srcs: [
         "src/**/*.java",
         "src/**/*.kt",
     ],
-    test_suites: [
-        "device-tests",
-        "mts",
-    ],
-    compile_multilib: "both",
     static_libs: [
+        "TetheringApiCurrentLib",
         "androidx.test.rules",
         "frameworks-base-testutils",
-        "net-tests-utils",
         "mockito-target-extended-minus-junit4",
-        "TetheringApiCurrentLib",
+        "net-tests-utils",
         "testables",
     ],
     // TODO(b/147200698) change sdk_version to module-current and
     // remove framework-minus-apex, ext, and framework-res
     sdk_version: "core_platform",
     libs: [
-        "framework-minus-apex",
-        "ext",
-        "framework-res",
         "android.test.runner",
         "android.test.base",
         "android.test.mock",
+        "ext",
+        "framework-minus-apex",
+        "framework-res",
         "framework-tethering",
     ],
     jni_libs: [
@@ -53,3 +47,25 @@
     ],
     jarjar_rules: "jarjar-rules.txt",
 }
+
+// Library containing the unit tests. This is used by the coverage test target to pull in the
+// unit test code. It is not currently used by the tests themselves because all the build
+// configuration needed by the tests is in the TetheringTestsDefaults rule.
+android_library {
+    name: "TetheringTestsLib",
+    defaults: ["TetheringTestsDefaults"],
+    visibility: [
+        "//frameworks/base/packages/Tethering/tests/integration",
+    ]
+}
+
+android_test {
+    name: "TetheringTests",
+    certificate: "platform",
+    test_suites: [
+        "device-tests",
+        "mts",
+    ],
+    defaults: ["TetheringTestsDefaults"],
+    compile_multilib: "both",
+}
diff --git a/Tethering/tests/unit/AndroidManifest.xml b/Tethering/tests/unit/AndroidManifest.xml
index 530bc07..31eaabf 100644
--- a/Tethering/tests/unit/AndroidManifest.xml
+++ b/Tethering/tests/unit/AndroidManifest.xml
@@ -16,11 +16,21 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
           package="com.android.networkstack.tethering.tests.unit">
 
+    <uses-permission android:name="android.permission.READ_PHONE_STATE"/>
     <uses-permission android:name="android.permission.TETHER_PRIVILEGED"/>
 
     <application android:debuggable="true">
         <uses-library android:name="android.test.runner" />
+        <service
+            android:name="com.android.networkstack.tethering.MockTetheringService"
+            android:permission="android.permission.TETHER_PRIVILEGED"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="com.android.networkstack.tethering.TetheringService"/>
+            </intent-filter>
+        </service>
     </application>
+
     <instrumentation android:name="androidx.test.runner.AndroidJUnitRunner"
         android:targetPackage="com.android.networkstack.tethering.tests.unit"
         android:label="Tethering service tests">
diff --git a/Tethering/tests/unit/src/android/net/dhcp/DhcpServingParamsParcelExtTest.java b/Tethering/tests/unit/src/android/net/dhcp/DhcpServingParamsParcelExtTest.java
index e8add98..f8eb147 100644
--- a/Tethering/tests/unit/src/android/net/dhcp/DhcpServingParamsParcelExtTest.java
+++ b/Tethering/tests/unit/src/android/net/dhcp/DhcpServingParamsParcelExtTest.java
@@ -42,7 +42,9 @@
 @SmallTest
 public class DhcpServingParamsParcelExtTest {
     private static final Inet4Address TEST_ADDRESS = inet4Addr("192.168.0.123");
+    private static final Inet4Address TEST_CLIENT_ADDRESS = inet4Addr("192.168.0.42");
     private static final int TEST_ADDRESS_PARCELED = 0xc0a8007b;
+    private static final int TEST_CLIENT_ADDRESS_PARCELED = 0xc0a8002a;
     private static final int TEST_PREFIX_LENGTH = 17;
     private static final int TEST_LEASE_TIME_SECS = 120;
     private static final int TEST_MTU = 1000;
@@ -105,6 +107,12 @@
         assertFalse(mParcel.metered);
     }
 
+    @Test
+    public void testSetClientAddr() {
+        mParcel.setSingleClientAddr(TEST_CLIENT_ADDRESS);
+        assertEquals(TEST_CLIENT_ADDRESS_PARCELED, mParcel.clientAddr);
+    }
+
     private static Inet4Address inet4Addr(String addr) {
         return (Inet4Address) parseNumericAddress(addr);
     }
diff --git a/Tethering/tests/unit/src/android/net/ip/IpServerTest.java b/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
index 3106e0e..f9be7b9 100644
--- a/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
+++ b/Tethering/tests/unit/src/android/net/ip/IpServerTest.java
@@ -43,7 +43,6 @@
 import static org.junit.Assert.fail;
 import static org.mockito.ArgumentMatchers.argThat;
 import static org.mockito.Matchers.any;
-import static org.mockito.Matchers.anyInt;
 import static org.mockito.Matchers.anyString;
 import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.doAnswer;
@@ -66,6 +65,7 @@
 import android.net.LinkProperties;
 import android.net.MacAddress;
 import android.net.RouteInfo;
+import android.net.TetherOffloadRuleParcel;
 import android.net.dhcp.DhcpServingParamsParcel;
 import android.net.dhcp.IDhcpServer;
 import android.net.dhcp.IDhcpServerCallbacks;
@@ -85,6 +85,7 @@
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.ArgumentCaptor;
+import org.mockito.ArgumentMatcher;
 import org.mockito.Captor;
 import org.mockito.InOrder;
 import org.mockito.Mock;
@@ -92,6 +93,7 @@
 
 import java.net.Inet4Address;
 import java.net.InetAddress;
+import java.util.Arrays;
 
 @RunWith(AndroidJUnit4.class)
 @SmallTest
@@ -514,6 +516,65 @@
         mLooper.dispatchAll();
     }
 
+    /**
+     * Custom ArgumentMatcher for TetherOffloadRuleParcel. This is needed because generated stable
+     * AIDL classes don't have equals(), so we cannot just use eq(). A custom assert, such as:
+     *
+     * private void checkFooCalled(StableParcelable p, ...) {
+     *     ArgumentCaptor<FooParam> captor = ArgumentCaptor.forClass(FooParam.class);
+     *     verify(mMock).foo(captor.capture());
+     *     Foo foo = captor.getValue();
+     *     assertFooMatchesExpectations(foo);
+     * }
+     *
+     * almost works, but not quite. This is because if the code under test calls foo() twice, the
+     * first call to checkFooCalled() matches both the calls, putting both calls into the captor,
+     * and then fails with TooManyActualInvocations. It also makes it harder to use other mockito
+     * features such as never(), inOrder(), etc.
+     *
+     * This approach isn't great because if the match fails, the error message is unhelpful
+     * (actual: "android.net.TetherOffloadRuleParcel@8c827b0" or some such), but at least it does
+     * work.
+     *
+     * See ConnectivityServiceTest#assertRoutesAdded for an alternative approach which solves the
+     * TooManyActualInvocations problem described above by forcing the caller of the custom assert
+     * method to specify all expected invocations in one call. This is useful when the stable
+     * parcelable class being asserted on has a corresponding Java object (eg., RouteInfo and
+     * RouteInfoParcelable), and the caller can just pass in a list of them. It not useful here
+     * because there is no such object.
+     */
+    private static class TetherOffloadRuleParcelMatcher implements
+            ArgumentMatcher<TetherOffloadRuleParcel> {
+        public final int upstreamIfindex;
+        public final InetAddress dst;
+        public final MacAddress dstMac;
+
+        TetherOffloadRuleParcelMatcher(int upstreamIfindex, InetAddress dst, MacAddress dstMac) {
+            this.upstreamIfindex = upstreamIfindex;
+            this.dst = dst;
+            this.dstMac = dstMac;
+        }
+
+        public boolean matches(TetherOffloadRuleParcel parcel) {
+            return upstreamIfindex == parcel.inputInterfaceIndex
+                    && (TEST_IFACE_PARAMS.index == parcel.outputInterfaceIndex)
+                    && Arrays.equals(dst.getAddress(), parcel.destination)
+                    && (128 == parcel.prefixLength)
+                    && Arrays.equals(TEST_IFACE_PARAMS.macAddr.toByteArray(), parcel.srcL2Address)
+                    && Arrays.equals(dstMac.toByteArray(), parcel.dstL2Address);
+        }
+
+        public String toString() {
+            return String.format("TetherOffloadRuleParcelMatcher(%d, %s, %s",
+                    upstreamIfindex, dst.getHostAddress(), dstMac);
+        }
+    }
+
+    private TetherOffloadRuleParcel matches(
+            int upstreamIfindex, InetAddress dst, MacAddress dstMac) {
+        return argThat(new TetherOffloadRuleParcelMatcher(upstreamIfindex, dst, dstMac));
+    }
+
     @Test
     public void addRemoveipv6ForwardingRules() throws Exception {
         initTetheredStateMachine(TETHERING_WIFI, UPSTREAM_IFACE, false /* usingLegacyDhcp */);
@@ -526,6 +587,7 @@
         final InetAddress neighB = InetAddresses.parseNumericAddress("2001:db8::2");
         final InetAddress neighLL = InetAddresses.parseNumericAddress("fe80::1");
         final InetAddress neighMC = InetAddresses.parseNumericAddress("ff02::1234");
+        final MacAddress macNull = MacAddress.fromString("00:00:00:00:00:00");
         final MacAddress macA = MacAddress.fromString("00:00:00:00:00:0a");
         final MacAddress macB = MacAddress.fromString("11:22:33:00:00:0b");
 
@@ -537,13 +599,11 @@
 
         // Events on this interface are received and sent to netd.
         recvNewNeigh(myIfindex, neighA, NUD_REACHABLE, macA);
-        verify(mNetd).tetherRuleAddDownstreamIpv6(eq(myIfindex), eq(UPSTREAM_IFINDEX),
-                eq(neighA.getAddress()), eq(myMac.toByteArray()), eq(macA.toByteArray()));
+        verify(mNetd).tetherOffloadRuleAdd(matches(UPSTREAM_IFINDEX, neighA, macA));
         reset(mNetd);
 
         recvNewNeigh(myIfindex, neighB, NUD_REACHABLE, macB);
-        verify(mNetd).tetherRuleAddDownstreamIpv6(eq(myIfindex), eq(UPSTREAM_IFINDEX),
-                eq(neighB.getAddress()), eq(myMac.toByteArray()), eq(macB.toByteArray()));
+        verify(mNetd).tetherOffloadRuleAdd(matches(UPSTREAM_IFINDEX, neighB, macB));
         reset(mNetd);
 
         // Link-local and multicast neighbors are ignored.
@@ -553,13 +613,14 @@
         verifyNoMoreInteractions(mNetd);
 
         // A neighbor that is no longer valid causes the rule to be removed.
-        recvNewNeigh(myIfindex, neighA, NUD_FAILED, macA);
-        verify(mNetd).tetherRuleRemoveDownstreamIpv6(eq(UPSTREAM_IFINDEX), eq(neighA.getAddress()));
+        // NUD_FAILED events do not have a MAC address.
+        recvNewNeigh(myIfindex, neighA, NUD_FAILED, null);
+        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighA, macNull));
         reset(mNetd);
 
         // A neighbor that is deleted causes the rule to be removed.
         recvDelNeigh(myIfindex, neighB, NUD_STALE, macB);
-        verify(mNetd).tetherRuleRemoveDownstreamIpv6(eq(UPSTREAM_IFINDEX), eq(neighB.getAddress()));
+        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighB, macNull));
         reset(mNetd);
 
         // Upstream changes result in deleting and re-adding the rules.
@@ -571,22 +632,16 @@
         LinkProperties lp = new LinkProperties();
         lp.setInterfaceName(UPSTREAM_IFACE2);
         dispatchTetherConnectionChanged(UPSTREAM_IFACE2, lp);
-        inOrder.verify(mNetd).tetherRuleAddDownstreamIpv6(eq(myIfindex), eq(UPSTREAM_IFINDEX2),
-                eq(neighA.getAddress()), eq(myMac.toByteArray()), eq(macA.toByteArray()));
-        inOrder.verify(mNetd).tetherRuleRemoveDownstreamIpv6(eq(UPSTREAM_IFINDEX),
-                    eq(neighA.getAddress()));
-        inOrder.verify(mNetd).tetherRuleAddDownstreamIpv6(eq(myIfindex), eq(UPSTREAM_IFINDEX2),
-                eq(neighB.getAddress()), eq(myMac.toByteArray()), eq(macB.toByteArray()));
-        inOrder.verify(mNetd).tetherRuleRemoveDownstreamIpv6(eq(UPSTREAM_IFINDEX),
-                eq(neighB.getAddress()));
+        inOrder.verify(mNetd).tetherOffloadRuleAdd(matches(UPSTREAM_IFINDEX2, neighA, macA));
+        inOrder.verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighA, macA));
+        inOrder.verify(mNetd).tetherOffloadRuleAdd(matches(UPSTREAM_IFINDEX2, neighB, macB));
+        inOrder.verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighB, macB));
         reset(mNetd);
 
         // When the upstream is lost, rules are removed.
         dispatchTetherConnectionChanged(null, null);
-        verify(mNetd).tetherRuleRemoveDownstreamIpv6(eq(UPSTREAM_IFINDEX2),
-                eq(neighA.getAddress()));
-        verify(mNetd).tetherRuleRemoveDownstreamIpv6(eq(UPSTREAM_IFINDEX2),
-                eq(neighB.getAddress()));
+        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX2, neighA, macA));
+        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX2, neighB, macB));
         reset(mNetd);
 
         // If the upstream is IPv4-only, no rules are added.
@@ -599,31 +654,27 @@
         lp.setInterfaceName(UPSTREAM_IFACE);
         dispatchTetherConnectionChanged(UPSTREAM_IFACE, lp);
         recvNewNeigh(myIfindex, neighB, NUD_REACHABLE, macB);
-        verify(mNetd).tetherRuleAddDownstreamIpv6(eq(myIfindex), eq(UPSTREAM_IFINDEX),
-                eq(neighB.getAddress()), eq(myMac.toByteArray()), eq(macB.toByteArray()));
-        verify(mNetd, never()).tetherRuleAddDownstreamIpv6(anyInt(), anyInt(),
-                eq(neighA.getAddress()), any(), any());
+        verify(mNetd).tetherOffloadRuleAdd(matches(UPSTREAM_IFINDEX, neighB, macB));
+        verify(mNetd, never()).tetherOffloadRuleAdd(matches(UPSTREAM_IFINDEX, neighA, macA));
 
         // If upstream IPv6 connectivity is lost, rules are removed.
         reset(mNetd);
         dispatchTetherConnectionChanged(UPSTREAM_IFACE, null);
-        verify(mNetd).tetherRuleRemoveDownstreamIpv6(eq(UPSTREAM_IFINDEX), eq(neighB.getAddress()));
+        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighB, macB));
 
         // When the interface goes down, rules are removed.
         lp.setInterfaceName(UPSTREAM_IFACE);
         dispatchTetherConnectionChanged(UPSTREAM_IFACE, lp);
         recvNewNeigh(myIfindex, neighA, NUD_REACHABLE, macA);
         recvNewNeigh(myIfindex, neighB, NUD_REACHABLE, macB);
-        verify(mNetd).tetherRuleAddDownstreamIpv6(eq(myIfindex), eq(UPSTREAM_IFINDEX),
-                eq(neighA.getAddress()), eq(myMac.toByteArray()), eq(macA.toByteArray()));
-        verify(mNetd).tetherRuleAddDownstreamIpv6(eq(myIfindex), eq(UPSTREAM_IFINDEX),
-                eq(neighB.getAddress()), eq(myMac.toByteArray()), eq(macB.toByteArray()));
+        verify(mNetd).tetherOffloadRuleAdd(matches(UPSTREAM_IFINDEX, neighA, macA));
+        verify(mNetd).tetherOffloadRuleAdd(matches(UPSTREAM_IFINDEX, neighB, macB));
         reset(mNetd);
 
         mIpServer.stop();
         mLooper.dispatchAll();
-        verify(mNetd).tetherRuleRemoveDownstreamIpv6(eq(UPSTREAM_IFINDEX), eq(neighA.getAddress()));
-        verify(mNetd).tetherRuleRemoveDownstreamIpv6(eq(UPSTREAM_IFINDEX), eq(neighB.getAddress()));
+        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighA, macA));
+        verify(mNetd).tetherOffloadRuleRemove(matches(UPSTREAM_IFINDEX, neighB, macB));
         reset(mNetd);
     }
 
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/ConnectedClientsTrackerTest.kt b/Tethering/tests/unit/src/com/android/networkstack/tethering/ConnectedClientsTrackerTest.kt
similarity index 98%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/ConnectedClientsTrackerTest.kt
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/ConnectedClientsTrackerTest.kt
index 1cdc3bb..d915354 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/ConnectedClientsTrackerTest.kt
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/ConnectedClientsTrackerTest.kt
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering
+package com.android.networkstack.tethering
 
 import android.net.LinkAddress
 import android.net.MacAddress
@@ -159,4 +159,4 @@
             return time
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/EntitlementManagerTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/EntitlementManagerTest.java
similarity index 92%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/EntitlementManagerTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/EntitlementManagerTest.java
index 0a7850b..8bd0edc 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/EntitlementManagerTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/EntitlementManagerTest.java
@@ -14,11 +14,13 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.TetheringManager.TETHERING_BLUETOOTH;
+import static android.net.TetheringManager.TETHERING_ETHERNET;
 import static android.net.TetheringManager.TETHERING_USB;
 import static android.net.TetheringManager.TETHERING_WIFI;
+import static android.net.TetheringManager.TETHERING_WIFI_P2P;
 import static android.net.TetheringManager.TETHER_ERROR_ENTITLEMENT_UNKNOWN;
 import static android.net.TetheringManager.TETHER_ERROR_NO_ERROR;
 import static android.net.TetheringManager.TETHER_ERROR_PROVISIONING_FAILED;
@@ -31,7 +33,6 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
 import static org.mockito.Matchers.anyBoolean;
 import static org.mockito.Matchers.anyInt;
 import static org.mockito.Matchers.anyString;
@@ -58,7 +59,6 @@
 import com.android.internal.util.State;
 import com.android.internal.util.StateMachine;
 import com.android.internal.util.test.BroadcastInterceptingContext;
-import com.android.networkstack.tethering.R;
 
 import org.junit.After;
 import org.junit.Before;
@@ -70,8 +70,6 @@
 import org.mockito.quality.Strictness;
 
 import java.util.ArrayList;
-import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.TimeUnit;
 
 @RunWith(AndroidJUnit4.class)
 @SmallTest
@@ -253,19 +251,16 @@
 
     @Test
     public void testRequestLastEntitlementCacheValue() throws Exception {
-        final CountDownLatch mCallbacklatch = new CountDownLatch(1);
         // 1. Entitlement check is not required.
         mEnMgr.fakeEntitlementResult = TETHER_ERROR_NO_ERROR;
         ResultReceiver receiver = new ResultReceiver(null) {
             @Override
             protected void onReceiveResult(int resultCode, Bundle resultData) {
                 assertEquals(TETHER_ERROR_NO_ERROR, resultCode);
-                mCallbacklatch.countDown();
             }
         };
         mEnMgr.requestLatestTetheringEntitlementResult(TETHERING_WIFI, receiver, true);
         mLooper.dispatchAll();
-        callbackTimeoutHelper(mCallbacklatch);
         assertEquals(0, mEnMgr.uiProvisionCount);
         mEnMgr.reset();
 
@@ -275,12 +270,10 @@
             @Override
             protected void onReceiveResult(int resultCode, Bundle resultData) {
                 assertEquals(TETHER_ERROR_ENTITLEMENT_UNKNOWN, resultCode);
-                mCallbacklatch.countDown();
             }
         };
         mEnMgr.requestLatestTetheringEntitlementResult(TETHERING_WIFI, receiver, false);
         mLooper.dispatchAll();
-        callbackTimeoutHelper(mCallbacklatch);
         assertEquals(0, mEnMgr.uiProvisionCount);
         mEnMgr.reset();
         // 3. No cache value and ui entitlement check is needed.
@@ -289,12 +282,10 @@
             @Override
             protected void onReceiveResult(int resultCode, Bundle resultData) {
                 assertEquals(TETHER_ERROR_PROVISIONING_FAILED, resultCode);
-                mCallbacklatch.countDown();
             }
         };
         mEnMgr.requestLatestTetheringEntitlementResult(TETHERING_WIFI, receiver, true);
         mLooper.dispatchAll();
-        callbackTimeoutHelper(mCallbacklatch);
         assertEquals(1, mEnMgr.uiProvisionCount);
         mEnMgr.reset();
         // 4. Cache value is TETHER_ERROR_PROVISIONING_FAILED and don't need to run entitlement
@@ -304,12 +295,10 @@
             @Override
             protected void onReceiveResult(int resultCode, Bundle resultData) {
                 assertEquals(TETHER_ERROR_PROVISIONING_FAILED, resultCode);
-                mCallbacklatch.countDown();
             }
         };
         mEnMgr.requestLatestTetheringEntitlementResult(TETHERING_WIFI, receiver, false);
         mLooper.dispatchAll();
-        callbackTimeoutHelper(mCallbacklatch);
         assertEquals(0, mEnMgr.uiProvisionCount);
         mEnMgr.reset();
         // 5. Cache value is TETHER_ERROR_PROVISIONING_FAILED and ui entitlement check is needed.
@@ -318,12 +307,10 @@
             @Override
             protected void onReceiveResult(int resultCode, Bundle resultData) {
                 assertEquals(TETHER_ERROR_NO_ERROR, resultCode);
-                mCallbacklatch.countDown();
             }
         };
         mEnMgr.requestLatestTetheringEntitlementResult(TETHERING_WIFI, receiver, true);
         mLooper.dispatchAll();
-        callbackTimeoutHelper(mCallbacklatch);
         assertEquals(1, mEnMgr.uiProvisionCount);
         mEnMgr.reset();
         // 6. Cache value is TETHER_ERROR_NO_ERROR.
@@ -332,12 +319,10 @@
             @Override
             protected void onReceiveResult(int resultCode, Bundle resultData) {
                 assertEquals(TETHER_ERROR_NO_ERROR, resultCode);
-                mCallbacklatch.countDown();
             }
         };
         mEnMgr.requestLatestTetheringEntitlementResult(TETHERING_WIFI, receiver, true);
         mLooper.dispatchAll();
-        callbackTimeoutHelper(mCallbacklatch);
         assertEquals(0, mEnMgr.uiProvisionCount);
         mEnMgr.reset();
         // 7. Test get value for other downstream type.
@@ -345,20 +330,24 @@
             @Override
             protected void onReceiveResult(int resultCode, Bundle resultData) {
                 assertEquals(TETHER_ERROR_ENTITLEMENT_UNKNOWN, resultCode);
-                mCallbacklatch.countDown();
             }
         };
         mEnMgr.requestLatestTetheringEntitlementResult(TETHERING_USB, receiver, false);
         mLooper.dispatchAll();
-        callbackTimeoutHelper(mCallbacklatch);
         assertEquals(0, mEnMgr.uiProvisionCount);
         mEnMgr.reset();
-    }
-
-    void callbackTimeoutHelper(final CountDownLatch latch) throws Exception {
-        if (!latch.await(1, TimeUnit.SECONDS)) {
-            fail("Timout, fail to receive callback");
-        }
+        // 8. Test get value for invalid downstream type.
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_NO_ERROR;
+        receiver = new ResultReceiver(null) {
+            @Override
+            protected void onReceiveResult(int resultCode, Bundle resultData) {
+                assertEquals(TETHER_ERROR_ENTITLEMENT_UNKNOWN, resultCode);
+            }
+        };
+        mEnMgr.requestLatestTetheringEntitlementResult(TETHERING_WIFI_P2P, receiver, true);
+        mLooper.dispatchAll();
+        assertEquals(0, mEnMgr.uiProvisionCount);
+        mEnMgr.reset();
     }
 
     @Test
@@ -471,6 +460,22 @@
         mLooper.dispatchAll();
         assertEquals(0, mEnMgr.uiProvisionCount);
         assertEquals(3, mEnMgr.silentProvisionCount);
+        assertFalse(mEnMgr.isCellularUpstreamPermitted());
+        mEnMgr.reset();
+        // 7. start ui provisioning, upstream is mobile, downstream is ethernet
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_NO_ERROR;
+        mEnMgr.startProvisioningIfNeeded(TETHERING_ETHERNET, true);
+        mLooper.dispatchAll();
+        assertEquals(1, mEnMgr.uiProvisionCount);
+        assertEquals(0, mEnMgr.silentProvisionCount);
+        assertTrue(mEnMgr.isCellularUpstreamPermitted());
+        mEnMgr.reset();
+        // 8. downstream is invalid
+        mEnMgr.fakeEntitlementResult = TETHER_ERROR_NO_ERROR;
+        mEnMgr.startProvisioningIfNeeded(TETHERING_WIFI_P2P, true);
+        mLooper.dispatchAll();
+        assertEquals(0, mEnMgr.uiProvisionCount);
+        assertEquals(0, mEnMgr.silentProvisionCount);
         mEnMgr.reset();
     }
 
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/IPv6TetheringCoordinatorTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/IPv6TetheringCoordinatorTest.java
new file mode 100644
index 0000000..820f255
--- /dev/null
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/IPv6TetheringCoordinatorTest.java
@@ -0,0 +1,156 @@
+/*
+ * 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.networkstack.tethering;
+
+import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
+import static android.net.RouteInfo.RTN_UNICAST;
+import static android.net.ip.IpServer.STATE_LOCAL_ONLY;
+import static android.net.ip.IpServer.STATE_TETHERED;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.reset;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
+
+import android.net.InetAddresses;
+import android.net.IpPrefix;
+import android.net.LinkAddress;
+import android.net.LinkProperties;
+import android.net.Network;
+import android.net.NetworkCapabilities;
+import android.net.RouteInfo;
+import android.net.ip.IpServer;
+import android.net.util.SharedLog;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import java.net.InetAddress;
+import java.util.ArrayList;
+import java.util.List;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class IPv6TetheringCoordinatorTest {
+    private static final String TEST_DNS_SERVER = "2001:4860:4860::8888";
+    private static final String TEST_INTERFACE = "test_rmnet0";
+    private static final String TEST_IPV6_ADDRESS = "2001:db8::1/64";
+    private static final String TEST_IPV4_ADDRESS = "192.168.100.1/24";
+
+    private IPv6TetheringCoordinator mIPv6TetheringCoordinator;
+    private ArrayList<IpServer> mNotifyList;
+
+    @Mock private SharedLog mSharedLog;
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+        when(mSharedLog.forSubComponent(anyString())).thenReturn(mSharedLog);
+        mNotifyList = new ArrayList<IpServer>();
+        mIPv6TetheringCoordinator = new IPv6TetheringCoordinator(mNotifyList, mSharedLog);
+    }
+
+    private UpstreamNetworkState createDualStackUpstream(final int transportType) {
+        final Network network = mock(Network.class);
+        final NetworkCapabilities netCap =
+                new NetworkCapabilities.Builder().addTransportType(transportType).build();
+        final InetAddress dns = InetAddresses.parseNumericAddress(TEST_DNS_SERVER);
+        final LinkProperties linkProp = new LinkProperties();
+        linkProp.setInterfaceName(TEST_INTERFACE);
+        linkProp.addLinkAddress(new LinkAddress(TEST_IPV6_ADDRESS));
+        linkProp.addLinkAddress(new LinkAddress(TEST_IPV4_ADDRESS));
+        linkProp.addRoute(new RouteInfo(new IpPrefix("::/0"), null, TEST_INTERFACE, RTN_UNICAST));
+        linkProp.addRoute(new RouteInfo(new IpPrefix("0.0.0.0/0"), null, TEST_INTERFACE,
+                    RTN_UNICAST));
+        linkProp.addDnsServer(dns);
+        return new UpstreamNetworkState(linkProp, netCap, network);
+    }
+
+    private void assertOnlyOneV6AddressAndNoV4(LinkProperties lp) {
+        assertEquals(lp.getInterfaceName(), TEST_INTERFACE);
+        assertFalse(lp.hasIpv4Address());
+        final List<LinkAddress> addresses = lp.getLinkAddresses();
+        assertEquals(addresses.size(), 1);
+        final LinkAddress v6Address = addresses.get(0);
+        assertEquals(v6Address, new LinkAddress(TEST_IPV6_ADDRESS));
+    }
+
+    @Test
+    public void testUpdateIpv6Upstream() throws Exception {
+        // 1. Add first IpServer.
+        final IpServer firstServer = mock(IpServer.class);
+        mNotifyList.add(firstServer);
+        mIPv6TetheringCoordinator.addActiveDownstream(firstServer, STATE_TETHERED);
+        verify(firstServer).sendMessage(IpServer.CMD_IPV6_TETHER_UPDATE, 0, 0, null);
+        verifyNoMoreInteractions(firstServer);
+
+        // 2. Add second IpServer and it would not have ipv6 tethering.
+        final IpServer secondServer = mock(IpServer.class);
+        mNotifyList.add(secondServer);
+        mIPv6TetheringCoordinator.addActiveDownstream(secondServer, STATE_LOCAL_ONLY);
+        verifyNoMoreInteractions(secondServer);
+        reset(firstServer, secondServer);
+
+        // 3. No upstream.
+        mIPv6TetheringCoordinator.updateUpstreamNetworkState(null);
+        verify(secondServer).sendMessage(IpServer.CMD_IPV6_TETHER_UPDATE, 0, 0, null);
+        reset(firstServer, secondServer);
+
+        // 4. Update ipv6 mobile upstream.
+        final UpstreamNetworkState mobileUpstream = createDualStackUpstream(TRANSPORT_CELLULAR);
+        final ArgumentCaptor<LinkProperties> lp = ArgumentCaptor.forClass(LinkProperties.class);
+        mIPv6TetheringCoordinator.updateUpstreamNetworkState(mobileUpstream);
+        verify(firstServer).sendMessage(eq(IpServer.CMD_IPV6_TETHER_UPDATE), eq(0), eq(0),
+                lp.capture());
+        final LinkProperties v6OnlyLink = lp.getValue();
+        assertOnlyOneV6AddressAndNoV4(v6OnlyLink);
+        verifyNoMoreInteractions(firstServer);
+        verifyNoMoreInteractions(secondServer);
+        reset(firstServer, secondServer);
+
+        // 5. Remove first IpServer.
+        mNotifyList.remove(firstServer);
+        mIPv6TetheringCoordinator.removeActiveDownstream(firstServer);
+        verify(firstServer).sendMessage(IpServer.CMD_IPV6_TETHER_UPDATE, 0, 0, null);
+        verify(secondServer).sendMessage(eq(IpServer.CMD_IPV6_TETHER_UPDATE), eq(0), eq(0),
+                lp.capture());
+        final LinkProperties localOnlyLink = lp.getValue();
+        assertNotNull(localOnlyLink);
+        assertNotEquals(localOnlyLink, v6OnlyLink);
+        reset(firstServer, secondServer);
+
+        // 6. Remove second IpServer.
+        mNotifyList.remove(secondServer);
+        mIPv6TetheringCoordinator.removeActiveDownstream(secondServer);
+        verifyNoMoreInteractions(firstServer);
+        verify(secondServer).sendMessage(IpServer.CMD_IPV6_TETHER_UPDATE, 0, 0, null);
+    }
+}
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/MockTetheringService.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/MockTetheringService.java
new file mode 100644
index 0000000..1c81c12
--- /dev/null
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/MockTetheringService.java
@@ -0,0 +1,56 @@
+/*
+ * 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.networkstack.tethering;
+
+import static org.mockito.Mockito.mock;
+
+import android.content.Intent;
+import android.net.ITetheringConnector;
+import android.os.Binder;
+import android.os.IBinder;
+
+public class MockTetheringService extends TetheringService {
+    private final Tethering mTethering = mock(Tethering.class);
+
+    @Override
+    public IBinder onBind(Intent intent) {
+        return new MockTetheringConnector(super.onBind(intent));
+    }
+
+    @Override
+    public Tethering makeTethering(TetheringDependencies deps) {
+        return mTethering;
+    }
+
+    public Tethering getTethering() {
+        return mTethering;
+    }
+
+    public class MockTetheringConnector extends Binder {
+        final IBinder mBase;
+        MockTetheringConnector(IBinder base) {
+            mBase = base;
+        }
+
+        public ITetheringConnector getTetheringConnector() {
+            return ITetheringConnector.Stub.asInterface(mBase);
+        }
+
+        public MockTetheringService getService() {
+            return MockTetheringService.this;
+        }
+    }
+}
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/OffloadControllerTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/OffloadControllerTest.java
similarity index 98%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/OffloadControllerTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/OffloadControllerTest.java
index fe84086..6579720 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/OffloadControllerTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/OffloadControllerTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.NetworkStats.DEFAULT_NETWORK_NO;
 import static android.net.NetworkStats.METERED_NO;
@@ -26,9 +26,9 @@
 import static android.net.RouteInfo.RTN_UNICAST;
 import static android.provider.Settings.Global.TETHER_OFFLOAD_DISABLED;
 
-import static com.android.server.connectivity.tethering.OffloadController.StatsType.STATS_PER_IFACE;
-import static com.android.server.connectivity.tethering.OffloadController.StatsType.STATS_PER_UID;
-import static com.android.server.connectivity.tethering.OffloadHardwareInterface.ForwardedStats;
+import static com.android.networkstack.tethering.OffloadController.StatsType.STATS_PER_IFACE;
+import static com.android.networkstack.tethering.OffloadController.StatsType.STATS_PER_UID;
+import static com.android.networkstack.tethering.OffloadHardwareInterface.ForwardedStats;
 import static com.android.testutils.MiscAssertsKt.assertContainsAll;
 import static com.android.testutils.MiscAssertsKt.assertThrows;
 import static com.android.testutils.NetworkStatsUtilsKt.orderInsensitiveEquals;
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringConfigurationTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringConfigurationTest.java
similarity index 99%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringConfigurationTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringConfigurationTest.java
index 3635964..07ddea4 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringConfigurationTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringConfigurationTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.ConnectivityManager.TYPE_ETHERNET;
 import static android.net.ConnectivityManager.TYPE_MOBILE;
@@ -44,7 +44,6 @@
 import androidx.test.runner.AndroidJUnit4;
 
 import com.android.internal.util.test.BroadcastInterceptingContext;
-import com.android.networkstack.tethering.R;
 
 import org.junit.After;
 import org.junit.Before;
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringNotificationUpdaterTest.kt b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringNotificationUpdaterTest.kt
new file mode 100644
index 0000000..04f31a7
--- /dev/null
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringNotificationUpdaterTest.kt
@@ -0,0 +1,483 @@
+/*
+ * 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.networkstack.tethering
+
+import android.app.Notification
+import android.app.NotificationManager
+import android.content.Context
+import android.content.res.Resources
+import android.net.ConnectivityManager.TETHERING_BLUETOOTH
+import android.net.ConnectivityManager.TETHERING_USB
+import android.net.ConnectivityManager.TETHERING_WIFI
+import android.os.Handler
+import android.os.HandlerThread
+import android.os.Looper
+import android.net.NetworkCapabilities
+import android.net.NetworkCapabilities.NET_CAPABILITY_NOT_ROAMING
+import android.os.UserHandle
+import android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID
+import android.telephony.TelephonyManager
+import androidx.test.filters.SmallTest
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.runner.AndroidJUnit4
+import com.android.internal.util.test.BroadcastInterceptingContext
+import com.android.networkstack.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE
+import com.android.networkstack.tethering.TetheringNotificationUpdater.ENABLE_NOTIFICATION_ID
+import com.android.networkstack.tethering.TetheringNotificationUpdater.EVENT_SHOW_NO_UPSTREAM
+import com.android.networkstack.tethering.TetheringNotificationUpdater.NO_UPSTREAM_NOTIFICATION_ID
+import com.android.networkstack.tethering.TetheringNotificationUpdater.RESTRICTED_NOTIFICATION_ID
+import com.android.networkstack.tethering.TetheringNotificationUpdater.ROAMING_NOTIFICATION_ID
+import com.android.networkstack.tethering.TetheringNotificationUpdater.VERIZON_CARRIER_ID
+import com.android.testutils.waitForIdle
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assert.fail
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.ArgumentCaptor
+import org.mockito.ArgumentMatchers.any
+import org.mockito.ArgumentMatchers.anyInt
+import org.mockito.ArgumentMatchers.eq
+import org.mockito.Mock
+import org.mockito.Mockito.doReturn
+import org.mockito.Mockito.never
+import org.mockito.Mockito.reset
+import org.mockito.Mockito.times
+import org.mockito.Mockito.verify
+import org.mockito.Mockito.verifyZeroInteractions
+import org.mockito.MockitoAnnotations
+
+const val TEST_SUBID = 1
+const val WIFI_ICON_ID = 1
+const val USB_ICON_ID = 2
+const val BT_ICON_ID = 3
+const val GENERAL_ICON_ID = 4
+const val WIFI_MASK = 1 shl TETHERING_WIFI
+const val USB_MASK = 1 shl TETHERING_USB
+const val BT_MASK = 1 shl TETHERING_BLUETOOTH
+const val TITLE = "Tethering active"
+const val MESSAGE = "Tap here to set up."
+const val TEST_TITLE = "Hotspot active"
+const val TEST_MESSAGE = "Tap to set up hotspot."
+const val TEST_NO_UPSTREAM_TITLE = "Hotspot has no internet access"
+const val TEST_NO_UPSTREAM_MESSAGE = "Device cannot connect to internet."
+const val TEST_NO_UPSTREAM_BUTTON = "Turn off hotspot"
+const val TEST_ROAMING_TITLE = "Hotspot is on"
+const val TEST_ROAMING_MESSAGE = "Additional charges may apply while roaming."
+
+@RunWith(AndroidJUnit4::class)
+@SmallTest
+class TetheringNotificationUpdaterTest {
+    // lateinit used here for mocks as they need to be reinitialized between each test and the test
+    // should crash if they are used before being initialized.
+    @Mock private lateinit var mockContext: Context
+    @Mock private lateinit var notificationManager: NotificationManager
+    @Mock private lateinit var telephonyManager: TelephonyManager
+    @Mock private lateinit var defaultResources: Resources
+    @Mock private lateinit var testResources: Resources
+
+    // lateinit for these classes under test, as they should be reset to a different instance for
+    // every test but should always be initialized before use (or the test should crash).
+    private lateinit var context: TestContext
+    private lateinit var notificationUpdater: TetheringNotificationUpdater
+    private lateinit var fakeTetheringThread: HandlerThread
+
+    private val ENABLE_ICON_CONFIGS = arrayOf(
+            "USB;android.test:drawable/usb", "BT;android.test:drawable/bluetooth",
+            "WIFI|BT;android.test:drawable/general", "WIFI|USB;android.test:drawable/general",
+            "USB|BT;android.test:drawable/general", "WIFI|USB|BT;android.test:drawable/general")
+
+    private val ROAMING_CAPABILITIES = NetworkCapabilities()
+    private val HOME_CAPABILITIES = NetworkCapabilities().addCapability(NET_CAPABILITY_NOT_ROAMING)
+    private val NOTIFICATION_ICON_ID = R.drawable.stat_sys_tether_general
+    private val TIMEOUT_MS = 500L
+
+    private inner class TestContext(c: Context) : BroadcastInterceptingContext(c) {
+        override fun createContextAsUser(user: UserHandle, flags: Int) =
+                if (user == UserHandle.ALL) mockContext else this
+        override fun getSystemService(name: String) =
+                if (name == Context.TELEPHONY_SERVICE) telephonyManager
+                else super.getSystemService(name)
+    }
+
+    private inner class WrappedNotificationUpdater(c: Context, looper: Looper)
+        : TetheringNotificationUpdater(c, looper) {
+        override fun getResourcesForSubId(context: Context, subId: Int) =
+                when (subId) {
+                    TEST_SUBID -> testResources
+                    INVALID_SUBSCRIPTION_ID -> defaultResources
+                    else -> super.getResourcesForSubId(context, subId)
+                }
+    }
+
+    private fun setupResources() {
+        doReturn(ENABLE_ICON_CONFIGS).`when`(defaultResources)
+                .getStringArray(R.array.tethering_notification_icons)
+        doReturn(arrayOf("WIFI;android.test:drawable/wifi")).`when`(testResources)
+                .getStringArray(R.array.tethering_notification_icons)
+        doReturn(5).`when`(testResources)
+                .getInteger(R.integer.delay_to_show_no_upstream_after_no_backhaul)
+        doReturn(true).`when`(testResources)
+                .getBoolean(R.bool.config_upstream_roaming_notification)
+        doReturn(TITLE).`when`(defaultResources).getString(R.string.tethering_notification_title)
+        doReturn(MESSAGE).`when`(defaultResources)
+                .getString(R.string.tethering_notification_message)
+        doReturn(TEST_TITLE).`when`(testResources).getString(R.string.tethering_notification_title)
+        doReturn(TEST_MESSAGE).`when`(testResources)
+                .getString(R.string.tethering_notification_message)
+        doReturn(TEST_NO_UPSTREAM_TITLE).`when`(testResources)
+                .getString(R.string.no_upstream_notification_title)
+        doReturn(TEST_NO_UPSTREAM_MESSAGE).`when`(testResources)
+                .getString(R.string.no_upstream_notification_message)
+        doReturn(TEST_NO_UPSTREAM_BUTTON).`when`(testResources)
+                .getString(R.string.no_upstream_notification_disable_button)
+        doReturn(TEST_ROAMING_TITLE).`when`(testResources)
+                .getString(R.string.upstream_roaming_notification_title)
+        doReturn(TEST_ROAMING_MESSAGE).`when`(testResources)
+                .getString(R.string.upstream_roaming_notification_message)
+        doReturn(USB_ICON_ID).`when`(defaultResources)
+                .getIdentifier(eq("android.test:drawable/usb"), any(), any())
+        doReturn(BT_ICON_ID).`when`(defaultResources)
+                .getIdentifier(eq("android.test:drawable/bluetooth"), any(), any())
+        doReturn(GENERAL_ICON_ID).`when`(defaultResources)
+                .getIdentifier(eq("android.test:drawable/general"), any(), any())
+        doReturn(WIFI_ICON_ID).`when`(testResources)
+                .getIdentifier(eq("android.test:drawable/wifi"), any(), any())
+    }
+
+    @Before
+    fun setUp() {
+        MockitoAnnotations.initMocks(this)
+        context = TestContext(InstrumentationRegistry.getInstrumentation().context)
+        doReturn(notificationManager).`when`(mockContext)
+                .getSystemService(Context.NOTIFICATION_SERVICE)
+        fakeTetheringThread = HandlerThread(this::class.simpleName)
+        fakeTetheringThread.start()
+        notificationUpdater = WrappedNotificationUpdater(context, fakeTetheringThread.looper)
+        setupResources()
+    }
+
+    @After
+    fun tearDown() {
+        fakeTetheringThread.quitSafely()
+    }
+
+    private fun Notification.title() = this.extras.getString(Notification.EXTRA_TITLE)
+    private fun Notification.text() = this.extras.getString(Notification.EXTRA_TEXT)
+
+    private fun verifyNotification(iconId: Int, title: String, text: String, id: Int) {
+        verify(notificationManager, never()).cancel(any(), eq(id))
+
+        val notificationCaptor = ArgumentCaptor.forClass(Notification::class.java)
+        verify(notificationManager, times(1))
+                .notify(any(), eq(id), notificationCaptor.capture())
+
+        val notification = notificationCaptor.getValue()
+        assertEquals(iconId, notification.smallIcon.resId)
+        assertEquals(title, notification.title())
+        assertEquals(text, notification.text())
+
+        reset(notificationManager)
+    }
+
+    private fun verifyNotificationCancelled(
+        notificationIds: List<Int>,
+        resetAfterVerified: Boolean = true
+    ) {
+        notificationIds.forEach {
+            verify(notificationManager, times(1)).cancel(any(), eq(it))
+        }
+        if (resetAfterVerified) reset(notificationManager)
+    }
+
+    @Test
+    fun testNotificationWithDownstreamChanged() {
+        // Wifi downstream. No notification.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyNotificationCancelled(listOf(ENABLE_NOTIFICATION_ID))
+
+        // Same downstream changed. Nothing happened.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyZeroInteractions(notificationManager)
+
+        // Wifi and usb downstreams. Show enable notification
+        notificationUpdater.onDownstreamChanged(WIFI_MASK or USB_MASK)
+        verifyNotification(GENERAL_ICON_ID, TITLE, MESSAGE, ENABLE_NOTIFICATION_ID)
+
+        // Usb downstream. Still show enable notification.
+        notificationUpdater.onDownstreamChanged(USB_MASK)
+        verifyNotification(USB_ICON_ID, TITLE, MESSAGE, ENABLE_NOTIFICATION_ID)
+
+        // No downstream. No notification.
+        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
+        verifyNotificationCancelled(listOf(ENABLE_NOTIFICATION_ID, NO_UPSTREAM_NOTIFICATION_ID,
+                ROAMING_NOTIFICATION_ID))
+    }
+
+    @Test
+    fun testNotificationWithActiveDataSubscriptionIdChanged() {
+        // Usb downstream. Showed enable notification with default resource.
+        notificationUpdater.onDownstreamChanged(USB_MASK)
+        verifyNotification(USB_ICON_ID, TITLE, MESSAGE, ENABLE_NOTIFICATION_ID)
+
+        // Same subId changed. Nothing happened.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(INVALID_SUBSCRIPTION_ID)
+        verifyZeroInteractions(notificationManager)
+
+        // Set test sub id. Clear notification with test resource.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
+        verifyNotificationCancelled(listOf(ENABLE_NOTIFICATION_ID, NO_UPSTREAM_NOTIFICATION_ID,
+                ROAMING_NOTIFICATION_ID))
+
+        // Wifi downstream. Show enable notification with test resource.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyNotification(WIFI_ICON_ID, TEST_TITLE, TEST_MESSAGE, ENABLE_NOTIFICATION_ID)
+
+        // No downstream. No notification.
+        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
+        verifyNotificationCancelled(listOf(ENABLE_NOTIFICATION_ID, NO_UPSTREAM_NOTIFICATION_ID,
+                ROAMING_NOTIFICATION_ID))
+    }
+
+    private fun assertIconNumbers(number: Int, configs: Array<String?>) {
+        doReturn(configs).`when`(defaultResources)
+                .getStringArray(R.array.tethering_notification_icons)
+        assertEquals(number, notificationUpdater.getIcons(
+                R.array.tethering_notification_icons, defaultResources).size())
+    }
+
+    @Test
+    fun testGetIcons() {
+        assertIconNumbers(0, arrayOfNulls<String>(0))
+        assertIconNumbers(0, arrayOf(null, ""))
+        assertIconNumbers(3, arrayOf(
+                // These configurations are invalid with wrong strings or symbols.
+                ";", ",", "|", "|,;", "WIFI", "1;2", " U SB; ", "bt;", "WIFI;USB;BT", "WIFI|USB|BT",
+                "WIFI,BT,USB", " WIFI| |  | USB, test:drawable/test",
+                // This configuration is valid with two downstream types (USB, BT).
+                "USB|,,,,,|BT;drawable/test ",
+                // This configuration is valid with one downstream types (WIFI).
+                "     WIFI     ; android.test:drawable/xxx "))
+    }
+
+    @Test
+    fun testGetDownstreamTypesMask() {
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask(""))
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("1"))
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("WIFI_P2P"))
+        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("usb"))
+        assertEquals(WIFI_MASK, notificationUpdater.getDownstreamTypesMask(" WIFI "))
+        assertEquals(USB_MASK, notificationUpdater.getDownstreamTypesMask("USB | B T"))
+        assertEquals(BT_MASK, notificationUpdater.getDownstreamTypesMask(" WIFI: | BT"))
+        assertEquals(WIFI_MASK or USB_MASK,
+                notificationUpdater.getDownstreamTypesMask("1|2|USB|WIFI|BLUETOOTH||"))
+    }
+
+    @Test
+    fun testSetupRestrictedNotification() {
+        val title = context.resources.getString(R.string.disable_tether_notification_title)
+        val message = context.resources.getString(R.string.disable_tether_notification_message)
+        val disallowTitle = "Tether function is disallowed"
+        val disallowMessage = "Please contact your admin"
+        doReturn(title).`when`(defaultResources)
+                .getString(R.string.disable_tether_notification_title)
+        doReturn(message).`when`(defaultResources)
+                .getString(R.string.disable_tether_notification_message)
+        doReturn(disallowTitle).`when`(testResources)
+                .getString(R.string.disable_tether_notification_title)
+        doReturn(disallowMessage).`when`(testResources)
+                .getString(R.string.disable_tether_notification_message)
+
+        // User restrictions on. Show restricted notification.
+        notificationUpdater.notifyTetheringDisabledByRestriction()
+        verifyNotification(NOTIFICATION_ICON_ID, title, message, RESTRICTED_NOTIFICATION_ID)
+
+        // User restrictions off. Clear notification.
+        notificationUpdater.tetheringRestrictionLifted()
+        verifyNotificationCancelled(listOf(RESTRICTED_NOTIFICATION_ID))
+
+        // Set test sub id. No notification.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
+        verifyNotificationCancelled(listOf(ENABLE_NOTIFICATION_ID, NO_UPSTREAM_NOTIFICATION_ID,
+                ROAMING_NOTIFICATION_ID))
+
+        // User restrictions on again. Show restricted notification with test resource.
+        notificationUpdater.notifyTetheringDisabledByRestriction()
+        verifyNotification(NOTIFICATION_ICON_ID, disallowTitle, disallowMessage,
+                RESTRICTED_NOTIFICATION_ID)
+    }
+
+    val MAX_BACKOFF_MS = 200L
+    /**
+     * Waits for all messages, including delayed ones, to be processed.
+     *
+     * This will wait until the handler has no more messages to be processed including
+     * delayed ones, or the timeout has expired. It uses an exponential backoff strategy
+     * to wait longer and longer to consume less CPU, with the max granularity being
+     * MAX_BACKOFF_MS.
+     *
+     * @return true if all messages have been processed including delayed ones, false if timeout
+     *
+     * TODO: Move this method to com.android.testutils.HandlerUtils.kt.
+     */
+    private fun Handler.waitForDelayedMessage(what: Int?, timeoutMs: Long) {
+        fun hasMatchingMessages() =
+                if (what == null) hasMessagesOrCallbacks() else hasMessages(what)
+        val expiry = System.currentTimeMillis() + timeoutMs
+        var delay = 5L
+        while (System.currentTimeMillis() < expiry && hasMatchingMessages()) {
+            // None of Handler, Looper, Message and MessageQueue expose any way to retrieve
+            // the time when the next (let alone the last) message will be processed, so
+            // short of examining the internals with reflection sleep() is the only solution.
+            Thread.sleep(delay)
+            delay = (delay * 2)
+                    .coerceAtMost(expiry - System.currentTimeMillis())
+                    .coerceAtMost(MAX_BACKOFF_MS)
+        }
+
+        val timeout = expiry - System.currentTimeMillis()
+        if (timeout <= 0) fail("Delayed message did not process yet after ${timeoutMs}ms")
+        waitForIdle(timeout)
+    }
+
+    @Test
+    fun testNotificationWithUpstreamCapabilitiesChanged_NoUpstream() {
+        // Set test sub id. No notification.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
+        verifyNotificationCancelled(listOf(ENABLE_NOTIFICATION_ID, NO_UPSTREAM_NOTIFICATION_ID,
+                ROAMING_NOTIFICATION_ID))
+
+        // Wifi downstream. Show enable notification with test resource.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyNotification(WIFI_ICON_ID, TEST_TITLE, TEST_MESSAGE, ENABLE_NOTIFICATION_ID)
+
+        // There is no upstream. Show no upstream notification.
+        notificationUpdater.onUpstreamCapabilitiesChanged(null)
+        notificationUpdater.handler.waitForDelayedMessage(EVENT_SHOW_NO_UPSTREAM, TIMEOUT_MS)
+        verifyNotification(NOTIFICATION_ICON_ID, TEST_NO_UPSTREAM_TITLE, TEST_NO_UPSTREAM_MESSAGE,
+                NO_UPSTREAM_NOTIFICATION_ID)
+
+        // Same capabilities changed. Nothing happened.
+        notificationUpdater.onUpstreamCapabilitiesChanged(null)
+        verifyZeroInteractions(notificationManager)
+
+        // Upstream come back. Clear no upstream notification.
+        notificationUpdater.onUpstreamCapabilitiesChanged(HOME_CAPABILITIES)
+        verifyNotificationCancelled(listOf(NO_UPSTREAM_NOTIFICATION_ID))
+
+        // No upstream again. Show no upstream notification.
+        notificationUpdater.onUpstreamCapabilitiesChanged(null)
+        notificationUpdater.handler.waitForDelayedMessage(EVENT_SHOW_NO_UPSTREAM, TIMEOUT_MS)
+        verifyNotification(NOTIFICATION_ICON_ID, TEST_NO_UPSTREAM_TITLE, TEST_NO_UPSTREAM_MESSAGE,
+                NO_UPSTREAM_NOTIFICATION_ID)
+
+        // No downstream. No notification.
+        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
+        verifyNotificationCancelled(listOf(ENABLE_NOTIFICATION_ID, NO_UPSTREAM_NOTIFICATION_ID,
+                ROAMING_NOTIFICATION_ID))
+
+        // Put up enable notification with wifi downstream and home capabilities.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        notificationUpdater.onUpstreamCapabilitiesChanged(HOME_CAPABILITIES)
+        verifyNotification(WIFI_ICON_ID, TEST_TITLE, TEST_MESSAGE, ENABLE_NOTIFICATION_ID)
+
+        // Set R.integer.delay_to_show_no_upstream_after_no_backhaul to -1 and change to no upstream
+        // again. Don't put up no upstream notification.
+        doReturn(-1).`when`(testResources)
+                .getInteger(R.integer.delay_to_show_no_upstream_after_no_backhaul)
+        notificationUpdater.onUpstreamCapabilitiesChanged(null)
+        notificationUpdater.handler.waitForDelayedMessage(EVENT_SHOW_NO_UPSTREAM, TIMEOUT_MS)
+        verifyNotificationCancelled(listOf(NO_UPSTREAM_NOTIFICATION_ID))
+    }
+
+    @Test
+    fun testGetResourcesForSubId() {
+        doReturn(telephonyManager).`when`(telephonyManager).createForSubscriptionId(anyInt())
+        doReturn(1234).`when`(telephonyManager).getSimCarrierId()
+        doReturn("000000").`when`(telephonyManager).getSimOperator()
+
+        val subId = -2 // Use invalid subId to avoid getting resource from cache or real subId.
+        val config = context.resources.configuration
+        var res = notificationUpdater.getResourcesForSubId(context, subId)
+        assertEquals(config.mcc, res.configuration.mcc)
+        assertEquals(config.mnc, res.configuration.mnc)
+
+        doReturn(VERIZON_CARRIER_ID).`when`(telephonyManager).getSimCarrierId()
+        res = notificationUpdater.getResourcesForSubId(context, subId)
+        assertEquals(config.mcc, res.configuration.mcc)
+        assertEquals(config.mnc, res.configuration.mnc)
+
+        doReturn("20404").`when`(telephonyManager).getSimOperator()
+        res = notificationUpdater.getResourcesForSubId(context, subId)
+        assertEquals(311, res.configuration.mcc)
+        assertEquals(480, res.configuration.mnc)
+    }
+
+    @Test
+    fun testNotificationWithUpstreamCapabilitiesChanged_Roaming() {
+        // Set test sub id. Clear notification.
+        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
+        verifyNotificationCancelled(listOf(ENABLE_NOTIFICATION_ID, NO_UPSTREAM_NOTIFICATION_ID,
+                ROAMING_NOTIFICATION_ID))
+
+        // Wifi downstream. Show enable notification with test resource.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyNotification(WIFI_ICON_ID, TEST_TITLE, TEST_MESSAGE, ENABLE_NOTIFICATION_ID)
+
+        // Upstream capabilities changed to roaming state. Show roaming notification.
+        notificationUpdater.onUpstreamCapabilitiesChanged(ROAMING_CAPABILITIES)
+        verifyNotification(NOTIFICATION_ICON_ID, TEST_ROAMING_TITLE, TEST_ROAMING_MESSAGE,
+                ROAMING_NOTIFICATION_ID)
+
+        // Same capabilities change. Nothing happened.
+        notificationUpdater.onUpstreamCapabilitiesChanged(ROAMING_CAPABILITIES)
+        verifyZeroInteractions(notificationManager)
+
+        // Upstream capabilities changed to home state. Clear roaming notification.
+        notificationUpdater.onUpstreamCapabilitiesChanged(HOME_CAPABILITIES)
+        verifyNotificationCancelled(listOf(ROAMING_NOTIFICATION_ID))
+
+        // Upstream capabilities changed to roaming state again. Show roaming notification.
+        notificationUpdater.onUpstreamCapabilitiesChanged(ROAMING_CAPABILITIES)
+        verifyNotification(NOTIFICATION_ICON_ID, TEST_ROAMING_TITLE, TEST_ROAMING_MESSAGE,
+                ROAMING_NOTIFICATION_ID)
+
+        // No upstream. Clear roaming notification and show no upstream notification.
+        notificationUpdater.onUpstreamCapabilitiesChanged(null)
+        notificationUpdater.handler.waitForDelayedMessage(EVENT_SHOW_NO_UPSTREAM, TIMEOUT_MS)
+        verifyNotificationCancelled(listOf(ROAMING_NOTIFICATION_ID), false)
+        verifyNotification(NOTIFICATION_ICON_ID, TEST_NO_UPSTREAM_TITLE, TEST_NO_UPSTREAM_MESSAGE,
+                NO_UPSTREAM_NOTIFICATION_ID)
+
+        // No downstream. No notification.
+        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
+        verifyNotificationCancelled(listOf(ENABLE_NOTIFICATION_ID, NO_UPSTREAM_NOTIFICATION_ID,
+                ROAMING_NOTIFICATION_ID))
+
+        // Wifi downstream again. Show enable notification with test resource.
+        notificationUpdater.onDownstreamChanged(WIFI_MASK)
+        verifyNotification(WIFI_ICON_ID, TEST_TITLE, TEST_MESSAGE, ENABLE_NOTIFICATION_ID)
+
+        // Set R.bool.config_upstream_roaming_notification to false and change upstream
+        // network to roaming state again. No roaming notification.
+        doReturn(false).`when`(testResources)
+                .getBoolean(R.bool.config_upstream_roaming_notification)
+        notificationUpdater.onUpstreamCapabilitiesChanged(ROAMING_CAPABILITIES)
+        verifyNotificationCancelled(listOf(NO_UPSTREAM_NOTIFICATION_ID, ROAMING_NOTIFICATION_ID))
+    }
+}
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringServiceTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringServiceTest.java
new file mode 100644
index 0000000..51bad9a
--- /dev/null
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringServiceTest.java
@@ -0,0 +1,194 @@
+/*
+ * 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.networkstack.tethering;
+
+import static android.net.TetheringManager.TETHERING_WIFI;
+import static android.net.TetheringManager.TETHER_ERROR_NO_ERROR;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
+
+import android.content.Intent;
+import android.net.IIntResultListener;
+import android.net.ITetheringConnector;
+import android.net.ITetheringEventCallback;
+import android.net.TetheringRequestParcel;
+import android.os.ResultReceiver;
+
+import androidx.test.InstrumentationRegistry;
+import androidx.test.filters.SmallTest;
+import androidx.test.rule.ServiceTestRule;
+import androidx.test.runner.AndroidJUnit4;
+
+import com.android.networkstack.tethering.MockTetheringService.MockTetheringConnector;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public final class TetheringServiceTest {
+    private static final String TEST_IFACE_NAME = "test_wlan0";
+    private static final String TEST_CALLER_PKG = "test_pkg";
+    @Mock private ITetheringEventCallback mITetheringEventCallback;
+    @Rule public ServiceTestRule mServiceTestRule;
+    private Tethering mTethering;
+    private Intent mMockServiceIntent;
+    private ITetheringConnector mTetheringConnector;
+
+    private class TestTetheringResult extends IIntResultListener.Stub {
+        private int mResult = -1; // Default value that does not match any result code.
+        @Override
+        public void onResult(final int resultCode) {
+            mResult = resultCode;
+        }
+
+        public void assertResult(final int expected) {
+            assertEquals(expected, mResult);
+        }
+    }
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+        mServiceTestRule = new ServiceTestRule();
+        mMockServiceIntent = new Intent(
+                InstrumentationRegistry.getTargetContext(),
+                MockTetheringService.class);
+        final MockTetheringConnector mockConnector =
+                (MockTetheringConnector) mServiceTestRule.bindService(mMockServiceIntent);
+        mTetheringConnector = mockConnector.getTetheringConnector();
+        final MockTetheringService service = mockConnector.getService();
+        mTethering = service.getTethering();
+        verify(mTethering).startStateMachineUpdaters();
+        when(mTethering.hasTetherableConfiguration()).thenReturn(true);
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        mServiceTestRule.unbindService();
+    }
+
+    @Test
+    public void testTether() throws Exception {
+        when(mTethering.tether(TEST_IFACE_NAME)).thenReturn(TETHER_ERROR_NO_ERROR);
+        final TestTetheringResult result = new TestTetheringResult();
+        mTetheringConnector.tether(TEST_IFACE_NAME, TEST_CALLER_PKG, result);
+        verify(mTethering).hasTetherableConfiguration();
+        verify(mTethering).tether(TEST_IFACE_NAME);
+        verifyNoMoreInteractions(mTethering);
+        result.assertResult(TETHER_ERROR_NO_ERROR);
+    }
+
+    @Test
+    public void testUntether() throws Exception {
+        when(mTethering.untether(TEST_IFACE_NAME)).thenReturn(TETHER_ERROR_NO_ERROR);
+        final TestTetheringResult result = new TestTetheringResult();
+        mTetheringConnector.untether(TEST_IFACE_NAME, TEST_CALLER_PKG, result);
+        verify(mTethering).hasTetherableConfiguration();
+        verify(mTethering).untether(TEST_IFACE_NAME);
+        verifyNoMoreInteractions(mTethering);
+        result.assertResult(TETHER_ERROR_NO_ERROR);
+    }
+
+    @Test
+    public void testSetUsbTethering() throws Exception {
+        when(mTethering.setUsbTethering(true /* enable */)).thenReturn(TETHER_ERROR_NO_ERROR);
+        final TestTetheringResult result = new TestTetheringResult();
+        mTetheringConnector.setUsbTethering(true /* enable */, TEST_CALLER_PKG, result);
+        verify(mTethering).hasTetherableConfiguration();
+        verify(mTethering).setUsbTethering(true /* enable */);
+        verifyNoMoreInteractions(mTethering);
+        result.assertResult(TETHER_ERROR_NO_ERROR);
+    }
+
+    @Test
+    public void testStartTethering() throws Exception {
+        final TestTetheringResult result = new TestTetheringResult();
+        final TetheringRequestParcel request = new TetheringRequestParcel();
+        request.tetheringType = TETHERING_WIFI;
+        mTetheringConnector.startTethering(request, TEST_CALLER_PKG, result);
+        verify(mTethering).hasTetherableConfiguration();
+        verify(mTethering).startTethering(eq(request), eq(result));
+        verifyNoMoreInteractions(mTethering);
+    }
+
+    @Test
+    public void testStopTethering() throws Exception {
+        final TestTetheringResult result = new TestTetheringResult();
+        mTetheringConnector.stopTethering(TETHERING_WIFI, TEST_CALLER_PKG, result);
+        verify(mTethering).hasTetherableConfiguration();
+        verify(mTethering).stopTethering(TETHERING_WIFI);
+        verifyNoMoreInteractions(mTethering);
+        result.assertResult(TETHER_ERROR_NO_ERROR);
+    }
+
+    @Test
+    public void testRequestLatestTetheringEntitlementResult() throws Exception {
+        final ResultReceiver result = new ResultReceiver(null);
+        mTetheringConnector.requestLatestTetheringEntitlementResult(TETHERING_WIFI, result,
+                true /* showEntitlementUi */, TEST_CALLER_PKG);
+        verify(mTethering).hasTetherableConfiguration();
+        verify(mTethering).requestLatestTetheringEntitlementResult(eq(TETHERING_WIFI),
+                eq(result), eq(true) /* showEntitlementUi */);
+        verifyNoMoreInteractions(mTethering);
+    }
+
+    @Test
+    public void testRegisterTetheringEventCallback() throws Exception {
+        mTetheringConnector.registerTetheringEventCallback(mITetheringEventCallback,
+                TEST_CALLER_PKG);
+        verify(mTethering).registerTetheringEventCallback(eq(mITetheringEventCallback));
+        verifyNoMoreInteractions(mTethering);
+    }
+
+    @Test
+    public void testUnregisterTetheringEventCallback() throws Exception {
+        mTetheringConnector.unregisterTetheringEventCallback(mITetheringEventCallback,
+                TEST_CALLER_PKG);
+        verify(mTethering).unregisterTetheringEventCallback(
+                eq(mITetheringEventCallback));
+        verifyNoMoreInteractions(mTethering);
+    }
+
+    @Test
+    public void testStopAllTethering() throws Exception {
+        final TestTetheringResult result = new TestTetheringResult();
+        mTetheringConnector.stopAllTethering(TEST_CALLER_PKG, result);
+        verify(mTethering).hasTetherableConfiguration();
+        verify(mTethering).untetherAll();
+        verifyNoMoreInteractions(mTethering);
+        result.assertResult(TETHER_ERROR_NO_ERROR);
+    }
+
+    @Test
+    public void testIsTetheringSupported() throws Exception {
+        final TestTetheringResult result = new TestTetheringResult();
+        mTetheringConnector.isTetheringSupported(TEST_CALLER_PKG, result);
+        verify(mTethering).hasTetherableConfiguration();
+        verifyNoMoreInteractions(mTethering);
+        result.assertResult(TETHER_ERROR_NO_ERROR);
+    }
+}
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
similarity index 95%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
index 0980514..28bfae0 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.hardware.usb.UsbManager.USB_CONFIGURED;
 import static android.hardware.usb.UsbManager.USB_CONNECTED;
@@ -38,6 +38,7 @@
 import static android.net.TetheringManager.TETHER_HARDWARE_OFFLOAD_STARTED;
 import static android.net.TetheringManager.TETHER_HARDWARE_OFFLOAD_STOPPED;
 import static android.net.dhcp.IDhcpServer.STATUS_SUCCESS;
+import static android.net.shared.Inet4AddressUtils.intToInet4AddressHTH;
 import static android.net.wifi.WifiManager.EXTRA_WIFI_AP_INTERFACE_NAME;
 import static android.net.wifi.WifiManager.EXTRA_WIFI_AP_MODE;
 import static android.net.wifi.WifiManager.EXTRA_WIFI_AP_STATE;
@@ -46,7 +47,8 @@
 import static android.net.wifi.WifiManager.WIFI_AP_STATE_ENABLED;
 import static android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID;
 
-import static com.android.server.connectivity.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE;
+import static com.android.networkstack.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE;
+import static com.android.networkstack.tethering.UpstreamNetworkMonitor.EVENT_ON_CAPABILITIES;
 
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
@@ -136,11 +138,12 @@
 import com.android.internal.util.StateMachine;
 import com.android.internal.util.test.BroadcastInterceptingContext;
 import com.android.internal.util.test.FakeSettingsProvider;
-import com.android.networkstack.tethering.R;
 import com.android.testutils.MiscAssertsKt;
 
 import org.junit.After;
+import org.junit.AfterClass;
 import org.junit.Before;
+import org.junit.BeforeClass;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.ArgumentCaptor;
@@ -381,7 +384,7 @@
         }
 
         @Override
-        public TetheringNotificationUpdater getNotificationUpdater(Context ctx) {
+        public TetheringNotificationUpdater getNotificationUpdater(Context ctx, Looper looper) {
             return mNotificationUpdater;
         }
     }
@@ -439,6 +442,18 @@
         return buildMobileUpstreamState(false, true, true);
     }
 
+    // See FakeSettingsProvider#clearSettingsProvider() that this needs to be called before and
+    // after use.
+    @BeforeClass
+    public static void setupOnce() {
+        FakeSettingsProvider.clearSettingsProvider();
+    }
+
+    @AfterClass
+    public static void tearDownOnce() {
+        FakeSettingsProvider.clearSettingsProvider();
+    }
+
     @Before
     public void setUp() throws Exception {
         MockitoAnnotations.initMocks(this);
@@ -484,6 +499,7 @@
         mServiceContext.registerReceiver(mBroadcastReceiver,
                 new IntentFilter(ACTION_TETHER_STATE_CHANGED));
         mTethering = makeTethering();
+        mTethering.startStateMachineUpdaters();
         verify(mStatsManager, times(1)).registerNetworkStatsProvider(anyString(), any());
         verify(mNetd).registerUnsolicitedEventListener(any());
         final ArgumentCaptor<PhoneStateListener> phoneListenerCaptor =
@@ -1653,10 +1669,13 @@
     }
 
     @Test
-    public void testRequestStaticServerIp() throws Exception {
-        final LinkAddress serverLinkAddr = new LinkAddress("192.168.20.1/24");
-        final LinkAddress clientLinkAddr = new LinkAddress("192.168.20.42/24");
-        final String serverAddr = "192.168.20.1";
+    public void testRequestStaticIp() throws Exception {
+        final LinkAddress serverLinkAddr = new LinkAddress("192.168.0.123/24");
+        final LinkAddress clientLinkAddr = new LinkAddress("192.168.0.42/24");
+        final String serverAddr = "192.168.0.123";
+        final int clientAddrParceled = 0xc0a8002a;
+        final ArgumentCaptor<DhcpServingParamsParcel> dhcpParamsCaptor =
+                ArgumentCaptor.forClass(DhcpServingParamsParcel.class);
         mTethering.startTethering(createTetheringRequestParcel(TETHERING_USB,
                   serverLinkAddr, clientLinkAddr), null);
         mLooper.dispatchAll();
@@ -1665,8 +1684,46 @@
         sendUsbBroadcast(true, true, true, TETHERING_USB);
         mLooper.dispatchAll();
         verify(mNetd).interfaceSetCfg(argThat(cfg -> serverAddr.equals(cfg.ipv4Addr)));
+        verify(mIpServerDependencies, times(1)).makeDhcpServer(any(), dhcpParamsCaptor.capture(),
+                any());
+        final DhcpServingParamsParcel params = dhcpParamsCaptor.getValue();
+        assertEquals(serverAddr, intToInet4AddressHTH(params.serverAddr).getHostAddress());
+        assertEquals(24, params.serverAddrPrefixLength);
+        assertEquals(clientAddrParceled, params.clientAddr);
+    }
 
-        // TODO: test static client address.
+    @Test
+    public void testUpstreamNetworkChanged() {
+        final Tethering.TetherMasterSM stateMachine = (Tethering.TetherMasterSM)
+                mTetheringDependencies.mUpstreamNetworkMonitorMasterSM;
+        final UpstreamNetworkState upstreamState = buildMobileIPv4UpstreamState();
+        when(mUpstreamNetworkMonitor.selectPreferredUpstreamType(any())).thenReturn(upstreamState);
+        stateMachine.chooseUpstreamType(true);
+
+        verify(mUpstreamNetworkMonitor, times(1)).setCurrentUpstream(eq(upstreamState.network));
+        verify(mNotificationUpdater, times(1)).onUpstreamCapabilitiesChanged(any());
+    }
+
+    @Test
+    public void testUpstreamCapabilitiesChanged() {
+        final Tethering.TetherMasterSM stateMachine = (Tethering.TetherMasterSM)
+                mTetheringDependencies.mUpstreamNetworkMonitorMasterSM;
+        final UpstreamNetworkState upstreamState = buildMobileIPv4UpstreamState();
+        when(mUpstreamNetworkMonitor.selectPreferredUpstreamType(any())).thenReturn(upstreamState);
+        stateMachine.chooseUpstreamType(true);
+
+        stateMachine.handleUpstreamNetworkMonitorCallback(EVENT_ON_CAPABILITIES, upstreamState);
+        // Should have two onUpstreamCapabilitiesChanged().
+        // One is called by reportUpstreamChanged(). One is called by EVENT_ON_CAPABILITIES.
+        verify(mNotificationUpdater, times(2)).onUpstreamCapabilitiesChanged(any());
+        reset(mNotificationUpdater);
+
+        // Verify that onUpstreamCapabilitiesChanged won't be called if not current upstream network
+        // capabilities changed.
+        final UpstreamNetworkState upstreamState2 = new UpstreamNetworkState(
+                upstreamState.linkProperties, upstreamState.networkCapabilities, new Network(101));
+        stateMachine.handleUpstreamNetworkMonitorCallback(EVENT_ON_CAPABILITIES, upstreamState2);
+        verify(mNotificationUpdater, never()).onUpstreamCapabilitiesChanged(any());
     }
 
     // TODO: Test that a request for hotspot mode doesn't interfere with an
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitorTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java
similarity index 99%
rename from Tethering/tests/unit/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitorTest.java
rename to Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java
index 7c98f62..232588c 100644
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/UpstreamNetworkMonitorTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/UpstreamNetworkMonitorTest.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.server.connectivity.tethering;
+package com.android.networkstack.tethering;
 
 import static android.net.ConnectivityManager.TYPE_MOBILE_DUN;
 import static android.net.ConnectivityManager.TYPE_MOBILE_HIPRI;
@@ -24,7 +24,7 @@
 import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
 import static android.net.NetworkCapabilities.TRANSPORT_WIFI;
 
-import static com.android.server.connectivity.tethering.UpstreamNetworkMonitor.TYPE_NONE;
+import static com.android.networkstack.tethering.UpstreamNetworkMonitor.TYPE_NONE;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
diff --git a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringNotificationUpdaterTest.kt b/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringNotificationUpdaterTest.kt
deleted file mode 100644
index b869491..0000000
--- a/Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringNotificationUpdaterTest.kt
+++ /dev/null
@@ -1,262 +0,0 @@
-/*
- * 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.tethering
-
-import android.app.Notification
-import android.app.NotificationManager
-import android.content.Context
-import android.content.res.Resources
-import android.net.ConnectivityManager.TETHERING_BLUETOOTH
-import android.net.ConnectivityManager.TETHERING_USB
-import android.net.ConnectivityManager.TETHERING_WIFI
-import android.os.UserHandle
-import android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID
-import androidx.test.platform.app.InstrumentationRegistry
-import androidx.test.filters.SmallTest
-import androidx.test.runner.AndroidJUnit4
-import com.android.internal.util.test.BroadcastInterceptingContext
-import com.android.networkstack.tethering.R
-import com.android.server.connectivity.tethering.TetheringNotificationUpdater.DOWNSTREAM_NONE
-import org.junit.Assert.assertEquals
-import org.junit.Before
-import org.junit.Test
-import org.junit.runner.RunWith
-import org.mockito.ArgumentCaptor
-import org.mockito.ArgumentMatchers.any
-import org.mockito.ArgumentMatchers.anyInt
-import org.mockito.ArgumentMatchers.eq
-import org.mockito.Mock
-import org.mockito.Mockito.doReturn
-import org.mockito.Mockito.never
-import org.mockito.Mockito.reset
-import org.mockito.Mockito.times
-import org.mockito.Mockito.verifyZeroInteractions
-import org.mockito.Mockito.verify
-import org.mockito.MockitoAnnotations
-
-const val TEST_SUBID = 1
-const val WIFI_ICON_ID = 1
-const val USB_ICON_ID = 2
-const val BT_ICON_ID = 3
-const val GENERAL_ICON_ID = 4
-const val WIFI_MASK = 1 shl TETHERING_WIFI
-const val USB_MASK = 1 shl TETHERING_USB
-const val BT_MASK = 1 shl TETHERING_BLUETOOTH
-const val TITTLE = "Tethering active"
-const val MESSAGE = "Tap here to set up."
-const val TEST_TITTLE = "Hotspot active"
-const val TEST_MESSAGE = "Tap to set up hotspot."
-
-@RunWith(AndroidJUnit4::class)
-@SmallTest
-class TetheringNotificationUpdaterTest {
-    // lateinit used here for mocks as they need to be reinitialized between each test and the test
-    // should crash if they are used before being initialized.
-    @Mock private lateinit var mockContext: Context
-    @Mock private lateinit var notificationManager: NotificationManager
-    @Mock private lateinit var defaultResources: Resources
-    @Mock private lateinit var testResources: Resources
-
-    // lateinit for this class under test, as it should be reset to a different instance for every
-    // tests but should always be initialized before use (or the test should crash).
-    private lateinit var notificationUpdater: TetheringNotificationUpdater
-
-    private val ENABLE_ICON_CONFIGS = arrayOf(
-            "USB;android.test:drawable/usb", "BT;android.test:drawable/bluetooth",
-            "WIFI|BT;android.test:drawable/general", "WIFI|USB;android.test:drawable/general",
-            "USB|BT;android.test:drawable/general", "WIFI|USB|BT;android.test:drawable/general")
-
-    private inner class TestContext(c: Context) : BroadcastInterceptingContext(c) {
-        override fun createContextAsUser(user: UserHandle, flags: Int) =
-                if (user == UserHandle.ALL) mockContext else this
-    }
-
-    private inner class WrappedNotificationUpdater(c: Context) : TetheringNotificationUpdater(c) {
-        override fun getResourcesForSubId(context: Context, subId: Int) =
-                if (subId == TEST_SUBID) testResources else defaultResources
-    }
-
-    private fun setupResources() {
-        doReturn(ENABLE_ICON_CONFIGS).`when`(defaultResources)
-                .getStringArray(R.array.tethering_notification_icons)
-        doReturn(arrayOf("WIFI;android.test:drawable/wifi")).`when`(testResources)
-                .getStringArray(R.array.tethering_notification_icons)
-        doReturn(TITTLE).`when`(defaultResources).getString(R.string.tethering_notification_title)
-        doReturn(MESSAGE).`when`(defaultResources)
-                .getString(R.string.tethering_notification_message)
-        doReturn(TEST_TITTLE).`when`(testResources).getString(R.string.tethering_notification_title)
-        doReturn(TEST_MESSAGE).`when`(testResources)
-                .getString(R.string.tethering_notification_message)
-        doReturn(USB_ICON_ID).`when`(defaultResources)
-                .getIdentifier(eq("android.test:drawable/usb"), any(), any())
-        doReturn(BT_ICON_ID).`when`(defaultResources)
-                .getIdentifier(eq("android.test:drawable/bluetooth"), any(), any())
-        doReturn(GENERAL_ICON_ID).`when`(defaultResources)
-                .getIdentifier(eq("android.test:drawable/general"), any(), any())
-        doReturn(WIFI_ICON_ID).`when`(testResources)
-                .getIdentifier(eq("android.test:drawable/wifi"), any(), any())
-    }
-
-    @Before
-    fun setUp() {
-        MockitoAnnotations.initMocks(this)
-        val context = TestContext(InstrumentationRegistry.getInstrumentation().context)
-        doReturn(notificationManager).`when`(mockContext)
-                .getSystemService(Context.NOTIFICATION_SERVICE)
-        notificationUpdater = WrappedNotificationUpdater(context)
-        setupResources()
-    }
-
-    private fun Notification.title() = this.extras.getString(Notification.EXTRA_TITLE)
-    private fun Notification.text() = this.extras.getString(Notification.EXTRA_TEXT)
-
-    private fun verifyNotification(iconId: Int = 0, title: String = "", text: String = "") {
-        verify(notificationManager, never()).cancel(any(), anyInt())
-
-        val notificationCaptor = ArgumentCaptor.forClass(Notification::class.java)
-        verify(notificationManager, times(1))
-                .notify(any(), anyInt(), notificationCaptor.capture())
-
-        val notification = notificationCaptor.getValue()
-        assertEquals(iconId, notification.smallIcon.resId)
-        assertEquals(title, notification.title())
-        assertEquals(text, notification.text())
-
-        reset(notificationManager)
-    }
-
-    private fun verifyNoNotification() {
-        verify(notificationManager, times(1)).cancel(any(), anyInt())
-        verify(notificationManager, never()).notify(any(), anyInt(), any())
-
-        reset(notificationManager)
-    }
-
-    @Test
-    fun testNotificationWithDownstreamChanged() {
-        // Wifi downstream. No notification.
-        notificationUpdater.onDownstreamChanged(WIFI_MASK)
-        verifyNoNotification()
-
-        // Same downstream changed. Nothing happened.
-        notificationUpdater.onDownstreamChanged(WIFI_MASK)
-        verifyZeroInteractions(notificationManager)
-
-        // Wifi and usb downstreams. Show enable notification
-        notificationUpdater.onDownstreamChanged(WIFI_MASK or USB_MASK)
-        verifyNotification(GENERAL_ICON_ID, TITTLE, MESSAGE)
-
-        // Usb downstream. Still show enable notification.
-        notificationUpdater.onDownstreamChanged(USB_MASK)
-        verifyNotification(USB_ICON_ID, TITTLE, MESSAGE)
-
-        // No downstream. No notification.
-        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
-        verifyNoNotification()
-    }
-
-    @Test
-    fun testNotificationWithActiveDataSubscriptionIdChanged() {
-        // Usb downstream. Showed enable notification with default resource.
-        notificationUpdater.onDownstreamChanged(USB_MASK)
-        verifyNotification(USB_ICON_ID, TITTLE, MESSAGE)
-
-        // Same subId changed. Nothing happened.
-        notificationUpdater.onActiveDataSubscriptionIdChanged(INVALID_SUBSCRIPTION_ID)
-        verifyZeroInteractions(notificationManager)
-
-        // Set test sub id. Clear notification with test resource.
-        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
-        verifyNoNotification()
-
-        // Wifi downstream. Show enable notification with test resource.
-        notificationUpdater.onDownstreamChanged(WIFI_MASK)
-        verifyNotification(WIFI_ICON_ID, TEST_TITTLE, TEST_MESSAGE)
-
-        // No downstream. No notification.
-        notificationUpdater.onDownstreamChanged(DOWNSTREAM_NONE)
-        verifyNoNotification()
-    }
-
-    private fun assertIconNumbers(number: Int, configs: Array<String?>) {
-        doReturn(configs).`when`(defaultResources)
-                .getStringArray(R.array.tethering_notification_icons)
-        assertEquals(number, notificationUpdater.getIcons(
-                R.array.tethering_notification_icons, defaultResources).size())
-    }
-
-    @Test
-    fun testGetIcons() {
-        assertIconNumbers(0, arrayOfNulls<String>(0))
-        assertIconNumbers(0, arrayOf(null, ""))
-        assertIconNumbers(3, arrayOf(
-                // These configurations are invalid with wrong strings or symbols.
-                ";", ",", "|", "|,;", "WIFI", "1;2", " U SB; ", "bt;", "WIFI;USB;BT", "WIFI|USB|BT",
-                "WIFI,BT,USB", " WIFI| |  | USB, test:drawable/test",
-                // This configuration is valid with two downstream types (USB, BT).
-                "USB|,,,,,|BT;drawable/test ",
-                // This configuration is valid with one downstream types (WIFI).
-                "     WIFI     ; android.test:drawable/xxx "))
-    }
-
-    @Test
-    fun testGetDownstreamTypesMask() {
-        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask(""))
-        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("1"))
-        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("WIFI_P2P"))
-        assertEquals(DOWNSTREAM_NONE, notificationUpdater.getDownstreamTypesMask("usb"))
-        assertEquals(WIFI_MASK, notificationUpdater.getDownstreamTypesMask(" WIFI "))
-        assertEquals(USB_MASK, notificationUpdater.getDownstreamTypesMask("USB | B T"))
-        assertEquals(BT_MASK, notificationUpdater.getDownstreamTypesMask(" WIFI: | BT"))
-        assertEquals(WIFI_MASK or USB_MASK,
-                notificationUpdater.getDownstreamTypesMask("1|2|USB|WIFI|BLUETOOTH||"))
-    }
-
-    @Test
-    fun testSetupRestrictedNotification() {
-        val title = InstrumentationRegistry.getInstrumentation().context.resources
-                .getString(R.string.disable_tether_notification_title)
-        val message = InstrumentationRegistry.getInstrumentation().context.resources
-                .getString(R.string.disable_tether_notification_message)
-        val disallowTitle = "Tether function is disallowed"
-        val disallowMessage = "Please contact your admin"
-        doReturn(title).`when`(defaultResources)
-                .getString(R.string.disable_tether_notification_title)
-        doReturn(message).`when`(defaultResources)
-                .getString(R.string.disable_tether_notification_message)
-        doReturn(disallowTitle).`when`(testResources)
-                .getString(R.string.disable_tether_notification_title)
-        doReturn(disallowMessage).`when`(testResources)
-                .getString(R.string.disable_tether_notification_message)
-
-        // User restrictions on. Show restricted notification.
-        notificationUpdater.notifyTetheringDisabledByRestriction()
-        verifyNotification(R.drawable.stat_sys_tether_general, title, message)
-
-        // User restrictions off. Clear notification.
-        notificationUpdater.tetheringRestrictionLifted()
-        verifyNoNotification()
-
-        // Set test sub id. No notification.
-        notificationUpdater.onActiveDataSubscriptionIdChanged(TEST_SUBID)
-        verifyNoNotification()
-
-        // User restrictions on again. Show restricted notification with test resource.
-        notificationUpdater.notifyTetheringDisabledByRestriction()
-        verifyNotification(R.drawable.stat_sys_tether_general, disallowTitle, disallowMessage)
-    }
-}
\ No newline at end of file