Remove BaseNetworkObserver from Nat464Xlat

Let ConnectivityService talk to Nat464Xlat through NetworkAgnetInfo
directly:
- Nat464Xlat will be created once there is a new network bringing up,
but Netd doesn't expose the method for unregistering unsolicited event.
- ConnectivityService has already registered netd unsolicited event
listener, so Nat464Xlat doesn't need to register unsolicited event
listenser by itself, it can get the unsolicited event from
ConnectivityService directly.

Bug: 174837473
Test: atest FrameworksNetTests
Change-Id: I751526e8ffa7d25591696ecd8d93b1585c4c20c7

services/core/java/com/android/server/ConnectivityService.java

@@ -8662,6 +8662,20 @@ public class ConnectivityService extends IConnectivityManager.Stub
                 long timestampNs, int uid) {
             mNetworkActivityTracker.setAndReportNetworkActive(isActive, timerLabel, timestampNs);
         }
+
+        @Override
+        public void onInterfaceLinkStateChanged(String iface, boolean up) {
+            for (NetworkAgentInfo nai: mNetworkAgentInfos) {
+                nai.clatd.interfaceLinkStateChanged(iface, up);
+            }
+        }
+
+        @Override
+        public void onInterfaceRemoved(String iface) {
+            for (NetworkAgentInfo nai: mNetworkAgentInfos) {
+                nai.clatd.interfaceRemoved(iface);
+            }
+        }
     }
 
     private final LegacyNetworkActivityTracker mNetworkActivityTracker;

services/core/java/com/android/server/connectivity/Nat464Xlat.java

@@ -36,7 +36,6 @@ import android.util.Log;
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.net.module.util.NetworkStackConstants;
-import com.android.server.net.BaseNetworkObserver;
 
 import java.net.Inet6Address;
 import java.util.Objects;
@@ -48,7 +47,7 @@ import java.util.Objects;
  *
  * @hide
  */
-public class Nat464Xlat extends BaseNetworkObserver {
+public class Nat464Xlat {
     private static final String TAG = Nat464Xlat.class.getSimpleName();
 
     // This must match the interface prefix in clatd.c.
@@ -174,13 +173,6 @@ public class Nat464Xlat extends BaseNetworkObserver {
      * and set internal state.
      */
     private void enterStartingState(String baseIface) {
-        try {
-            mNMService.registerObserver(this);
-        } catch (RemoteException e) {
-            Log.e(TAG, "Can't register iface observer for clat on " + mNetwork.toShortString());
-            return;
-        }
-
         mNat64PrefixInUse = selectNat64Prefix();
         String addrStr = null;
         try {
@@ -216,11 +208,6 @@ public class Nat464Xlat extends BaseNetworkObserver {
      * Unregister as a base observer for the stacked interface, and clear internal state.
      */
     private void leaveStartedState() {
-        try {
-            mNMService.unregisterObserver(this);
-        } catch (RemoteException | IllegalStateException e) {
-            Log.e(TAG, "Error unregistering clatd observer on " + mBaseIface + ": " + e);
-        }
         mNat64PrefixInUse = null;
         mIface = null;
         mBaseIface = null;
@@ -507,12 +494,10 @@ public class Nat464Xlat extends BaseNetworkObserver {
         stop();
     }
 
-    @Override
     public void interfaceLinkStateChanged(String iface, boolean up) {
         mNetwork.handler().post(() -> { handleInterfaceLinkStateChanged(iface, up); });
     }
 
-    @Override
     public void interfaceRemoved(String iface) {
         mNetwork.handler().post(() -> handleInterfaceRemoved(iface));
     }

tests/net/java/com/android/server/connectivity/Nat464XlatTest.java

@@ -206,7 +206,6 @@ public class Nat464XlatTest {
         // Start clat.
         nat.start();
 
-        verify(mNms).registerObserver(eq(nat));
         verify(mNetd).clatdStart(eq(BASE_IFACE), eq(NAT64_PREFIX));
 
         // Stacked interface up notification arrives.
@@ -225,7 +224,6 @@ public class Nat464XlatTest {
 
         verify(mNetd).clatdStop(eq(BASE_IFACE));
         verify(mConnectivity, times(2)).handleUpdateLinkProperties(eq(mNai), c.capture());
-        verify(mNms).unregisterObserver(eq(nat));
         assertTrue(c.getValue().getStackedLinks().isEmpty());
         assertFalse(c.getValue().getAllInterfaceNames().contains(STACKED_IFACE));
         verify(mDnsResolver).stopPrefix64Discovery(eq(NETID));
@@ -346,7 +344,6 @@ public class Nat464XlatTest {
 
         nat.start();
 
-        verify(mNms).registerObserver(eq(nat));
         verify(mNetd).clatdStart(eq(BASE_IFACE), eq(NAT64_PREFIX));
 
         // Stacked interface up notification arrives.
@@ -365,7 +362,6 @@ public class Nat464XlatTest {
 
         verify(mNetd).clatdStop(eq(BASE_IFACE));
         verify(mConnectivity, times(2)).handleUpdateLinkProperties(eq(mNai), c.capture());
-        verify(mNms).unregisterObserver(eq(nat));
         verify(mDnsResolver).stopPrefix64Discovery(eq(NETID));
         assertTrue(c.getValue().getStackedLinks().isEmpty());
         assertFalse(c.getValue().getAllInterfaceNames().contains(STACKED_IFACE));
@@ -386,7 +382,6 @@ public class Nat464XlatTest {
 
         nat.start();
 
-        verify(mNms).registerObserver(eq(nat));
         verify(mNetd).clatdStart(eq(BASE_IFACE), eq(NAT64_PREFIX));
 
         // ConnectivityService immediately stops clat (Network disconnects, IPv4 addr appears, ...)
@@ -394,7 +389,6 @@ public class Nat464XlatTest {
         nat.stop();
 
         verify(mNetd).clatdStop(eq(BASE_IFACE));
-        verify(mNms).unregisterObserver(eq(nat));
         verify(mDnsResolver).stopPrefix64Discovery(eq(NETID));
         assertIdle(nat);
 
@@ -430,7 +424,6 @@ public class Nat464XlatTest {
 
         nat.start();
 
-        verify(mNms).registerObserver(eq(nat));
         verify(mNetd).clatdStart(eq(BASE_IFACE), eq(NAT64_PREFIX));
 
         // ConnectivityService immediately stops clat (Network disconnects, IPv4 addr appears, ...)
@@ -438,7 +431,6 @@ public class Nat464XlatTest {
         nat.stop();
 
         verify(mNetd).clatdStop(eq(BASE_IFACE));
-        verify(mNms).unregisterObserver(eq(nat));
         verify(mDnsResolver).stopPrefix64Discovery(eq(NETID));
         assertIdle(nat);