Ensure IkeV2VpnRunnerCallback is always called by the mExecutor thread

Bug: 229799060
Test: atest FrameworksNetTests:VpnTest
      atest CtsNetTestCases:Ikev2VpnTest
Change-Id: I4bfaf79abaad3cec6f6629fb8bc885a4916a820b

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

@@ -2527,7 +2527,9 @@ public class Vpn {
             super(TAG);
             mProfile = profile;
             mIpSecManager = (IpSecManager) mContext.getSystemService(Context.IPSEC_SERVICE);
-            mNetworkCallback = new VpnIkev2Utils.Ikev2VpnNetworkCallback(TAG, this);
+            // Pass mExecutor into Ikev2VpnNetworkCallback and make sure that IkeV2VpnRunnerCallback
+            // will be called by the mExecutor thread.
+            mNetworkCallback = new VpnIkev2Utils.Ikev2VpnNetworkCallback(TAG, this, mExecutor);
             mSessionKey = UUID.randomUUID().toString();
         }
 
@@ -2682,16 +2684,12 @@ public class Vpn {
          * <p>The Ikev2VpnRunner will unconditionally switch to the new network, killing the old IKE
          * state in the process, and starting a new IkeSession instance.
          *
-         * <p>This method is called multiple times over the lifetime of the Ikev2VpnRunner, and is
+         * <p>This method MUST always be called on the mExecutor thread in order to ensure
-         * called on the ConnectivityService thread. Thus, the actual work MUST be proxied to the
+         * consistency of the Ikev2VpnRunner fields.
-         * mExecutor thread in order to ensure consistency of the Ikev2VpnRunner fields.
          */
         public void onDefaultNetworkChanged(@NonNull Network network) {
             Log.d(TAG, "Starting IKEv2/IPsec session on new network: " + network);
 
-            // Proxy to the Ikev2VpnRunner (single-thread) executor to ensure consistency in lieu
-            // of locking.
-            mExecutor.execute(() -> {
             try {
                 if (!mIsRunning) {
                     Log.d(TAG, "onDefaultNetworkChanged after exit");
@@ -2748,7 +2746,6 @@ public class Vpn {
                 Log.i(TAG, "Setup failed for network " + network + ". Aborting", e);
                 onSessionLost(network, e);
             }
-            });
         }
 
         /** Marks the state as FAILED, and disconnects. */

services/core/java/com/android/server/connectivity/VpnIkev2Utils.java

@@ -86,6 +86,7 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.List;
+import java.util.concurrent.ExecutorService;
 
 /**
  * Utility class to build and convert IKEv2/IPsec parameters.
@@ -376,22 +377,25 @@ public class VpnIkev2Utils {
     static class Ikev2VpnNetworkCallback extends NetworkCallback {
         private final String mTag;
         private final Vpn.IkeV2VpnRunnerCallback mCallback;
+        private final ExecutorService mExecutor;
 
-        Ikev2VpnNetworkCallback(String tag, Vpn.IkeV2VpnRunnerCallback callback) {
+        Ikev2VpnNetworkCallback(String tag, Vpn.IkeV2VpnRunnerCallback callback,
+                ExecutorService executor) {
             mTag = tag;
             mCallback = callback;
+            mExecutor = executor;
         }
 
         @Override
         public void onAvailable(@NonNull Network network) {
             Log.d(mTag, "Starting IKEv2/IPsec session on new network: " + network);
-            mCallback.onDefaultNetworkChanged(network);
+            mExecutor.execute(() -> mCallback.onDefaultNetworkChanged(network));
         }
 
         @Override
         public void onLost(@NonNull Network network) {
             Log.d(mTag, "Tearing down; lost network: " + network);
-            mCallback.onSessionLost(network, null);
+            mExecutor.execute(() -> mCallback.onSessionLost(network, null));
         }
     }