Export API of listening for network change events in app2

Currently, due to foreground app will never get blocked by
NetworkPolicyManagerService, so onBlockedStatusChanged cannot be
tested under cts net app.

Thus, listen for network change events in app2 allows subsequent
tests on NetworkCallbacks.

Bug: 118862340
Test: m -j cts
Change-Id: I26ca370fc6ae4dd3f32ce6cf448bae83f3fbfbcc

tests/cts/hostside/aidl/Android.mk

@@ -19,6 +19,7 @@ LOCAL_MODULE_TAGS := tests
 LOCAL_SDK_VERSION := current
 LOCAL_SRC_FILES := \
         com/android/cts/net/hostside/IMyService.aidl \
+        com/android/cts/net/hostside/INetworkCallback.aidl \
         com/android/cts/net/hostside/INetworkStateObserver.aidl \
         com/android/cts/net/hostside/IRemoteSocketFactory.aidl
 LOCAL_MODULE := CtsHostsideNetworkTestsAidl

tests/cts/hostside/aidl/com/android/cts/net/hostside/IMyService.aidl

@@ -16,10 +16,13 @@
 
 package com.android.cts.net.hostside;
 
+import com.android.cts.net.hostside.INetworkCallback;
+
 interface IMyService {
     void registerBroadcastReceiver();
     int getCounters(String receiverName, String action);
     String checkNetworkStatus();
     String getRestrictBackgroundStatus();
     void sendNotification(int notificationId, String notificationType);
+    void registerNetworkCallback(in INetworkCallback cb);
 }

tests/cts/hostside/aidl/com/android/cts/net/hostside/INetworkCallback.aidl

@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2019 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.cts.net.hostside;
+
+import android.net.Network;
+
+interface INetworkCallback {
+    void onBlockedStatusChanged(in Network network, boolean blocked);
+    void onAvailable(in Network network);
+    void onLost(in Network network);
+}

tests/cts/hostside/app/src/com/android/cts/net/hostside/AbstractRestrictBackgroundNetworkTestCase.java

@@ -962,6 +962,10 @@ abstract class AbstractRestrictBackgroundNetworkTestCase extends Instrumentation
         fail("app2 receiver is not ready");
     }
 
+    protected void registerNetworkCallback(INetworkCallback cb) throws Exception {
+        mServiceClient.registerNetworkCallback(cb);
+    }
+
     /**
      * Registers a {@link NotificationListenerService} implementation that will execute the
      * notification actions right after the notification is sent.

tests/cts/hostside/app/src/com/android/cts/net/hostside/MyServiceClient.java

@@ -26,8 +26,6 @@ import android.os.RemoteException;
 
 import com.android.cts.net.hostside.IMyService;
 
-import java.io.FileDescriptor;
-
 public class MyServiceClient {
     private static final int TIMEOUT_MS = 5000;
     private static final String PACKAGE = MyServiceClient.class.getPackage().getName();
@@ -98,4 +96,8 @@ public class MyServiceClient {
     public void sendNotification(int notificationId, String notificationType) throws RemoteException {
         mService.sendNotification(notificationId, notificationType);
     }
+
+    public void registerNetworkCallback(INetworkCallback cb) throws RemoteException {
+        mService.registerNetworkCallback(cb);
+    }
 }

tests/cts/hostside/app2/src/com/android/cts/net/hostside/app2/MyService.java

@@ -16,6 +16,7 @@
 package com.android.cts.net.hostside.app2;
 
 import static android.net.ConnectivityManager.ACTION_RESTRICT_BACKGROUND_CHANGED;
+
 import static com.android.cts.net.hostside.app2.Common.ACTION_RECEIVER_READY;
 import static com.android.cts.net.hostside.app2.Common.DYNAMIC_RECEIVER;
 import static com.android.cts.net.hostside.app2.Common.TAG;
@@ -26,13 +27,16 @@ import android.app.Service;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
-import android.content.SharedPreferences;
+import android.net.ConnectivityManager;
+import android.net.Network;
+import android.net.NetworkCapabilities;
+import android.net.NetworkRequest;
 import android.os.IBinder;
-import android.os.Looper;
+import android.os.RemoteException;
 import android.util.Log;
-import android.widget.Toast;
 
 import com.android.cts.net.hostside.IMyService;
+import com.android.cts.net.hostside.INetworkCallback;
 
 /**
  * Service used to dynamically register a broadcast receiver.
@@ -40,7 +44,10 @@ import com.android.cts.net.hostside.IMyService;
 public class MyService extends Service {
     private static final String NOTIFICATION_CHANNEL_ID = "MyService";
 
+    ConnectivityManager mCm;
+
     private MyBroadcastReceiver mReceiver;
+    private ConnectivityManager.NetworkCallback mNetworkCallback;
 
     // TODO: move MyBroadcast static functions here - they were kept there to make git diff easier.
 
@@ -81,8 +88,67 @@ public class MyService extends Service {
             MyBroadcastReceiver .sendNotification(getApplicationContext(), NOTIFICATION_CHANNEL_ID,
                     notificationId, notificationType);
         }
+
+        @Override
+        public void registerNetworkCallback(INetworkCallback cb) {
+            if (mNetworkCallback != null) {
+                Log.d(TAG, "unregister previous network callback: " + mNetworkCallback);
+                unregisterNetworkCallback();
+            }
+            Log.d(TAG, "registering network callback");
+
+            mNetworkCallback = new ConnectivityManager.NetworkCallback() {
+                @Override
+                public void onBlockedStatusChanged(Network network, boolean blocked) {
+                    try {
+                        cb.onBlockedStatusChanged(network, blocked);
+                    } catch (RemoteException e) {
+                        Log.d(TAG, "Cannot send onBlockedStatusChanged: " + e);
+                        unregisterNetworkCallback();
+                    }
+                }
+
+                @Override
+                public void onAvailable(Network network) {
+                    try {
+                        cb.onAvailable(network);
+                    } catch (RemoteException e) {
+                        Log.d(TAG, "Cannot send onAvailable: " + e);
+                        unregisterNetworkCallback();
+                    }
+                }
+
+                @Override
+                public void onLost(Network network) {
+                    try {
+                        cb.onLost(network);
+                    } catch (RemoteException e) {
+                        Log.d(TAG, "Cannot send onLost: " + e);
+                        unregisterNetworkCallback();
+                    }
+                }
+            };
+            mCm.registerNetworkCallback(makeWifiNetworkRequest(), mNetworkCallback);
+            try {
+                cb.asBinder().linkToDeath(() -> unregisterNetworkCallback(), 0);
+            } catch (RemoteException e) {
+                unregisterNetworkCallback();
+            }
+        }
       };
 
+    private void unregisterNetworkCallback() {
+        Log.d(TAG, "unregistering network callback");
+        mCm.unregisterNetworkCallback(mNetworkCallback);
+        mNetworkCallback = null;
+    }
+
+    private NetworkRequest makeWifiNetworkRequest() {
+        return new NetworkRequest.Builder()
+                .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
+                .build();
+    }
+
     @Override
     public IBinder onBind(Intent intent) {
         return mBinder;
@@ -94,6 +160,8 @@ public class MyService extends Service {
         ((NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE))
                 .createNotificationChannel(new NotificationChannel(NOTIFICATION_CHANNEL_ID,
                         NOTIFICATION_CHANNEL_ID, NotificationManager.IMPORTANCE_DEFAULT));
+        mCm = (ConnectivityManager) getApplicationContext()
+                .getSystemService(Context.CONNECTIVITY_SERVICE);
     }
 
     @Override