Add support for Ethernet tethering

Ethernet tethering can be started via
startTethering(TETHERING_ETHERNET).

Test: flashed, enabled ethernet tethering, verified internet access on
      downstream.
Bug: 130840861

Merged-In: I34842acd94b972e440c3622f7617df10c18acf65
Change-Id: I34842acd94b972e440c3622f7617df10c18acf65
(cherry-pick with conflicts in test-current.txt)
diff --git a/api/system-current.txt b/api/system-current.txt
index 13715a3..1ab457e 100755
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -1577,6 +1577,7 @@
     field public static final String BUGREPORT_SERVICE = "bugreport";
     field public static final String CONTENT_SUGGESTIONS_SERVICE = "content_suggestions";
     field public static final String CONTEXTHUB_SERVICE = "contexthub";
+    field public static final String ETHERNET_SERVICE = "ethernet";
     field public static final String EUICC_CARD_SERVICE = "euicc_card";
     field public static final String HDMI_CONTROL_SERVICE = "hdmi_control";
     field public static final String NETD_SERVICE = "netd";
@@ -4382,6 +4383,19 @@
     method @Deprecated public void onUpstreamChanged(@Nullable android.net.Network);
   }
 
+  public class EthernetManager {
+    method @NonNull public android.net.EthernetManager.TetheredInterfaceRequest requestTetheredInterface(@NonNull android.net.EthernetManager.TetheredInterfaceCallback);
+  }
+
+  public static interface EthernetManager.TetheredInterfaceCallback {
+    method public void onAvailable(@NonNull String);
+    method public void onUnavailable();
+  }
+
+  public static class EthernetManager.TetheredInterfaceRequest {
+    method public void release();
+  }
+
   public class InvalidPacketException extends java.lang.Exception {
     ctor public InvalidPacketException(int);
     field public static final int ERROR_INVALID_IP_ADDRESS = -21; // 0xffffffeb
@@ -4755,6 +4769,7 @@
     field public static final String EXTRA_AVAILABLE_TETHER = "availableArray";
     field public static final String EXTRA_ERRORED_TETHER = "erroredArray";
     field public static final int TETHERING_BLUETOOTH = 2; // 0x2
+    field public static final int TETHERING_ETHERNET = 5; // 0x5
     field public static final int TETHERING_INVALID = -1; // 0xffffffff
     field public static final int TETHERING_NCM = 4; // 0x4
     field public static final int TETHERING_USB = 1; // 0x1
diff --git a/api/test-current.txt b/api/test-current.txt
index 554371d..b9d53db 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -653,6 +653,7 @@
     method public void setContentCaptureOptions(@Nullable android.content.ContentCaptureOptions);
     field public static final String BUGREPORT_SERVICE = "bugreport";
     field public static final String CONTENT_CAPTURE_MANAGER_SERVICE = "content_capture";
+    field public static final String ETHERNET_SERVICE = "ethernet";
     field public static final String NETWORK_STACK_SERVICE = "network_stack";
     field public static final String PERMISSION_SERVICE = "permission";
     field public static final String ROLLBACK_SERVICE = "rollback";
@@ -1392,6 +1393,19 @@
     field public static final String EXTRA_CAPTIVE_PORTAL_USER_AGENT = "android.net.extra.CAPTIVE_PORTAL_USER_AGENT";
   }
 
+  public class EthernetManager {
+    method @NonNull public android.net.EthernetManager.TetheredInterfaceRequest requestTetheredInterface(@NonNull android.net.EthernetManager.TetheredInterfaceCallback);
+  }
+
+  public static interface EthernetManager.TetheredInterfaceCallback {
+    method public void onAvailable(@NonNull String);
+    method public void onUnavailable();
+  }
+
+  public static class EthernetManager.TetheredInterfaceRequest {
+    method public void release();
+  }
+
   public final class IpPrefix implements android.os.Parcelable {
     ctor public IpPrefix(@NonNull java.net.InetAddress, @IntRange(from=0, to=128) int);
     ctor public IpPrefix(@NonNull String);
@@ -1540,6 +1554,7 @@
     field public static final String EXTRA_AVAILABLE_TETHER = "availableArray";
     field public static final String EXTRA_ERRORED_TETHER = "erroredArray";
     field public static final int TETHERING_BLUETOOTH = 2; // 0x2
+    field public static final int TETHERING_ETHERNET = 5; // 0x5
     field public static final int TETHERING_INVALID = -1; // 0xffffffff
     field public static final int TETHERING_NCM = 4; // 0x4
     field public static final int TETHERING_USB = 1; // 0x1
diff --git a/core/java/android/content/Context.java b/core/java/android/content/Context.java
index 8fa00ab..c3c7f97 100644
--- a/core/java/android/content/Context.java
+++ b/core/java/android/content/Context.java
@@ -4022,16 +4022,16 @@
     public static final String LOWPAN_SERVICE = "lowpan";
 
     /**
-     * Use with {@link #getSystemService(String)} to retrieve a {@link
-     * android.net.EthernetManager} for handling management of
-     * Ethernet access.
+     * Use with {@link #getSystemService(String)} to retrieve a {@link android.net.EthernetManager}
+     * for handling management of Ethernet access.
      *
      * @see #getSystemService(String)
      * @see android.net.EthernetManager
      *
      * @hide
      */
-    @UnsupportedAppUsage
+    @SystemApi
+    @TestApi
     public static final String ETHERNET_SERVICE = "ethernet";
 
     /**
diff --git a/core/java/android/net/EthernetManager.java b/core/java/android/net/EthernetManager.java
index 95000f5..a3899b7 100644
--- a/core/java/android/net/EthernetManager.java
+++ b/core/java/android/net/EthernetManager.java
@@ -17,7 +17,9 @@
 package android.net;
 
 import android.annotation.NonNull;
+import android.annotation.SystemApi;
 import android.annotation.SystemService;
+import android.annotation.TestApi;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.content.Context;
 import android.os.Handler;
@@ -32,6 +34,8 @@
  *
  * @hide
  */
+@SystemApi
+@TestApi
 @SystemService(Context.ETHERNET_SERVICE)
 public class EthernetManager {
     private static final String TAG = "EthernetManager";
@@ -62,12 +66,14 @@
 
     /**
      * A listener interface to receive notification on changes in Ethernet.
+     * @hide
      */
     public interface Listener {
         /**
          * Called when Ethernet port's availability is changed.
          * @param iface Ethernet interface name
          * @param isAvailable {@code true} if Ethernet port exists.
+         * @hide
          */
         @UnsupportedAppUsage
         void onAvailabilityChanged(String iface, boolean isAvailable);
@@ -78,6 +84,7 @@
      * Applications will almost always want to use
      * {@link android.content.Context#getSystemService Context.getSystemService()} to retrieve
      * the standard {@link android.content.Context#ETHERNET_SERVICE Context.ETHERNET_SERVICE}.
+     * @hide
      */
     public EthernetManager(Context context, IEthernetManager service) {
         mContext = context;
@@ -87,6 +94,7 @@
     /**
      * Get Ethernet configuration.
      * @return the Ethernet Configuration, contained in {@link IpConfiguration}.
+     * @hide
      */
     @UnsupportedAppUsage
     public IpConfiguration getConfiguration(String iface) {
@@ -99,6 +107,7 @@
 
     /**
      * Set Ethernet configuration.
+     * @hide
      */
     @UnsupportedAppUsage
     public void setConfiguration(String iface, IpConfiguration config) {
@@ -111,6 +120,7 @@
 
     /**
      * Indicates whether the system currently has one or more Ethernet interfaces.
+     * @hide
      */
     @UnsupportedAppUsage
     public boolean isAvailable() {
@@ -121,6 +131,7 @@
      * Indicates whether the system has given interface.
      *
      * @param iface Ethernet interface name
+     * @hide
      */
     @UnsupportedAppUsage
     public boolean isAvailable(String iface) {
@@ -135,6 +146,7 @@
      * Adds a listener.
      * @param listener A {@link Listener} to add.
      * @throws IllegalArgumentException If the listener is null.
+     * @hide
      */
     @UnsupportedAppUsage
     public void addListener(Listener listener) {
@@ -153,6 +165,7 @@
 
     /**
      * Returns an array of available Ethernet interface names.
+     * @hide
      */
     @UnsupportedAppUsage
     public String[] getAvailableInterfaces() {
@@ -167,6 +180,7 @@
      * Removes a listener.
      * @param listener A {@link Listener} to remove.
      * @throws IllegalArgumentException If the listener is null.
+     * @hide
      */
     @UnsupportedAppUsage
     public void removeListener(Listener listener) {
diff --git a/packages/Tethering/common/TetheringLib/src/android/net/TetheringManager.java b/packages/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
index 79c69304..37ce1d57 100644
--- a/packages/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
+++ b/packages/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
@@ -136,6 +136,12 @@
      */
     public static final int TETHERING_NCM = 4;
 
+    /**
+     * Ethernet tethering type.
+     * @see #startTethering(TetheringRequest, Executor, StartTetheringCallback)
+     */
+    public static final int TETHERING_ETHERNET = 5;
+
     public static final int TETHER_ERROR_NO_ERROR           = 0;
     public static final int TETHER_ERROR_UNKNOWN_IFACE      = 1;
     public static final int TETHER_ERROR_SERVICE_UNAVAIL    = 2;
diff --git a/packages/Tethering/src/android/net/ip/IpServer.java b/packages/Tethering/src/android/net/ip/IpServer.java
index 57cc4dd..190d2509 100644
--- a/packages/Tethering/src/android/net/ip/IpServer.java
+++ b/packages/Tethering/src/android/net/ip/IpServer.java
@@ -93,6 +93,8 @@
     private static final int WIFI_HOST_IFACE_PREFIX_LENGTH = 24;
     private static final String WIFI_P2P_IFACE_ADDR = "192.168.49.1";
     private static final int WIFI_P2P_IFACE_PREFIX_LENGTH = 24;
+    private static final String ETHERNET_IFACE_ADDR = "192.168.50.1";
+    private static final int ETHERNET_IFACE_PREFIX_LENGTH = 24;
 
     // TODO: have PanService use some visible version of this constant
     private static final String BLUETOOTH_IFACE_ADDR = "192.168.44.1";
@@ -426,6 +428,10 @@
             } else if (mInterfaceType == TetheringManager.TETHERING_WIFI_P2P) {
                 srvAddr = (Inet4Address) parseNumericAddress(WIFI_P2P_IFACE_ADDR);
                 prefixLen = WIFI_P2P_IFACE_PREFIX_LENGTH;
+            } else if (mInterfaceType == TetheringManager.TETHERING_ETHERNET) {
+                // TODO: randomize address for tethering too, similarly to wifi
+                srvAddr = (Inet4Address) parseNumericAddress(ETHERNET_IFACE_ADDR);
+                prefixLen = ETHERNET_IFACE_PREFIX_LENGTH;
             } else {
                 // BT configures the interface elsewhere: only start DHCP.
                 // TODO: make all tethering types behave the same way, and delete the bluetooth
diff --git a/packages/Tethering/src/com/android/server/connectivity/tethering/Tethering.java b/packages/Tethering/src/com/android/server/connectivity/tethering/Tethering.java
index 0b05d97..5b35bb6 100644
--- a/packages/Tethering/src/com/android/server/connectivity/tethering/Tethering.java
+++ b/packages/Tethering/src/com/android/server/connectivity/tethering/Tethering.java
@@ -30,6 +30,7 @@
 import static android.net.TetheringManager.EXTRA_AVAILABLE_TETHER;
 import static android.net.TetheringManager.EXTRA_ERRORED_TETHER;
 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_NCM;
 import static android.net.TetheringManager.TETHERING_USB;
@@ -68,6 +69,7 @@
 import android.content.res.Resources;
 import android.hardware.usb.UsbManager;
 import android.net.ConnectivityManager;
+import android.net.EthernetManager;
 import android.net.IIntResultListener;
 import android.net.INetd;
 import android.net.ITetheringEventCallback;
@@ -112,6 +114,7 @@
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
+import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.IndentingPrintWriter;
 import com.android.internal.util.MessageUtils;
@@ -214,6 +217,13 @@
     private boolean mDataSaverEnabled = false;
     private String mWifiP2pTetherInterface = null;
 
+    @GuardedBy("mPublicSync")
+    private EthernetManager.TetheredInterfaceRequest mEthernetIfaceRequest;
+    @GuardedBy("mPublicSync")
+    private String mConfiguredEthernetIface;
+    @GuardedBy("mPublicSync")
+    private EthernetCallback mEthernetCallback;
+
     public Tethering(TetheringDependencies deps) {
         mLog.mark("Tethering.constructed");
         mDeps = deps;
@@ -464,6 +474,10 @@
                 result = setNcmTethering(enable);
                 sendTetherResult(listener, result);
                 break;
+            case TETHERING_ETHERNET:
+                result = setEthernetTethering(enable);
+                sendTetherResult(listener, result);
+                break;
             default:
                 Log.w(TAG, "Invalid tether type.");
                 sendTetherResult(listener, TETHER_ERROR_UNKNOWN_IFACE);
@@ -540,6 +554,57 @@
         }, BluetoothProfile.PAN);
     }
 
+    private int setEthernetTethering(final boolean enable) {
+        final EthernetManager em = (EthernetManager) mContext.getSystemService(
+                Context.ETHERNET_SERVICE);
+        synchronized (mPublicSync) {
+            if (enable) {
+                mEthernetCallback = new EthernetCallback();
+                mEthernetIfaceRequest = em.requestTetheredInterface(mEthernetCallback);
+            } else {
+                if (mConfiguredEthernetIface != null) {
+                    stopEthernetTetheringLocked();
+                    mEthernetIfaceRequest.release();
+                }
+                mEthernetCallback = null;
+            }
+        }
+        return TETHER_ERROR_NO_ERROR;
+    }
+
+    private void stopEthernetTetheringLocked() {
+        if (mConfiguredEthernetIface == null) return;
+        changeInterfaceState(mConfiguredEthernetIface, IpServer.STATE_AVAILABLE);
+        stopTrackingInterfaceLocked(mConfiguredEthernetIface);
+        mConfiguredEthernetIface = null;
+    }
+
+    private class EthernetCallback implements EthernetManager.TetheredInterfaceCallback {
+        @Override
+        public void onAvailable(String iface) {
+            synchronized (mPublicSync) {
+                if (this != mEthernetCallback) {
+                    // Ethernet callback arrived after Ethernet tethering stopped. Ignore.
+                    return;
+                }
+                maybeTrackNewInterfaceLocked(iface, TETHERING_ETHERNET);
+                changeInterfaceState(iface, IpServer.STATE_TETHERED);
+                mConfiguredEthernetIface = iface;
+            }
+        }
+
+        @Override
+        public void onUnavailable() {
+            synchronized (mPublicSync) {
+                if (this != mEthernetCallback) {
+                    // onAvailable called after stopping Ethernet tethering.
+                    return;
+                }
+                stopEthernetTetheringLocked();
+            }
+        }
+    }
+
     int tether(String iface) {
         return tether(iface, IpServer.STATE_TETHERED);
     }
@@ -590,6 +655,7 @@
         stopTethering(TETHERING_WIFI_P2P);
         stopTethering(TETHERING_USB);
         stopTethering(TETHERING_BLUETOOTH);
+        stopTethering(TETHERING_ETHERNET);
     }
 
     int getLastTetherError(String iface) {
diff --git a/packages/Tethering/tests/unit/Android.bp b/packages/Tethering/tests/unit/Android.bp
index 53782fed..13174c5 100644
--- a/packages/Tethering/tests/unit/Android.bp
+++ b/packages/Tethering/tests/unit/Android.bp
@@ -19,6 +19,7 @@
     certificate: "platform",
     srcs: [
         "src/**/*.java",
+        "src/**/*.kt",
     ],
     test_suites: [
         "device-tests",
diff --git a/packages/Tethering/tests/unit/AndroidManifest.xml b/packages/Tethering/tests/unit/AndroidManifest.xml
index 0a1cdd3..530bc07 100644
--- a/packages/Tethering/tests/unit/AndroidManifest.xml
+++ b/packages/Tethering/tests/unit/AndroidManifest.xml
@@ -16,6 +16,8 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
           package="com.android.networkstack.tethering.tests.unit">
 
+    <uses-permission android:name="android.permission.TETHER_PRIVILEGED"/>
+
     <application android:debuggable="true">
         <uses-library android:name="android.test.runner" />
     </application>