Add ConnectivityManager.getActiveNetwork().

Rework NetID allocation in ConnectivityService so registerNetworkAgent() can
return the allocated NetID.

Bug: 19416463
Change-Id: I68e395552cf27422c80b4dfae5db5d56a0d68f5d

core/java/android/net/ConnectivityManager.java

@@ -601,6 +601,27 @@ public class ConnectivityManager {
         }
     }
 
+    /**
+     * Returns a {@link Network} object corresponding to the currently active
+     * default data network.  In the event that the current active default data
+     * network disconnects, the returned {@code Network} object will no longer
+     * be usable.  This will return {@code null} when there is no default
+     * network.
+     *
+     * @return a {@link Network} object for the current default network or
+     *        {@code null} if no default network is currently active
+     *
+     * <p>This method requires the caller to hold the permission
+     * {@link android.Manifest.permission#ACCESS_NETWORK_STATE}.
+     */
+    public Network getActiveNetwork() {
+        try {
+            return mService.getActiveNetwork();
+        } catch (RemoteException e) {
+            return null;
+        }
+    }
+
     /**
      * Returns details about the currently active default data network
      * for a given uid.  This is for internal use only to avoid spying
@@ -1927,12 +1948,18 @@ public class ConnectivityManager {
         } catch (RemoteException e) { }
     }
 
-    /** {@hide} */
-    public void registerNetworkAgent(Messenger messenger, NetworkInfo ni, LinkProperties lp,
+    /**
+     * @hide
+     * Register a NetworkAgent with ConnectivityService.
+     * @return NetID corresponding to NetworkAgent.
+     */
+    public int registerNetworkAgent(Messenger messenger, NetworkInfo ni, LinkProperties lp,
             NetworkCapabilities nc, int score, NetworkMisc misc) {
         try {
-            mService.registerNetworkAgent(messenger, ni, lp, nc, score, misc);
-        } catch (RemoteException e) { }
+            return mService.registerNetworkAgent(messenger, ni, lp, nc, score, misc);
+        } catch (RemoteException e) {
+            return NETID_UNSET;
+        }
     }
 
     /**

core/java/android/net/IConnectivityManager.aidl

@@ -42,6 +42,7 @@ import com.android.internal.net.VpnProfile;
 /** {@hide} */
 interface IConnectivityManager
 {
+    Network getActiveNetwork();
     NetworkInfo getActiveNetworkInfo();
     NetworkInfo getActiveNetworkInfoForUid(int uid);
     NetworkInfo getNetworkInfo(int networkType);
@@ -132,7 +133,7 @@ interface IConnectivityManager
 
     void unregisterNetworkFactory(in Messenger messenger);
 
-    void registerNetworkAgent(in Messenger messenger, in NetworkInfo ni, in LinkProperties lp,
+    int registerNetworkAgent(in Messenger messenger, in NetworkInfo ni, in LinkProperties lp,
             in NetworkCapabilities nc, int score, in NetworkMisc misc);
 
     NetworkRequest requestNetwork(in NetworkCapabilities networkCapabilities,

core/java/android/net/NetworkAgent.java

@@ -42,6 +42,10 @@ import java.util.concurrent.atomic.AtomicBoolean;
  * @hide
  */
 public abstract class NetworkAgent extends Handler {
+    // Guaranteed to be valid (not NETID_UNSET), otherwise registerNetworkAgent() would have thrown
+    // an exception.
+    public final int netId;
+
     private volatile AsyncChannel mAsyncChannel;
     private final String LOG_TAG;
     private static final boolean DBG = true;
@@ -142,7 +146,7 @@ public abstract class NetworkAgent extends Handler {
         if (VDBG) log("Registering NetworkAgent");
         ConnectivityManager cm = (ConnectivityManager)mContext.getSystemService(
                 Context.CONNECTIVITY_SERVICE);
-        cm.registerNetworkAgent(new Messenger(this), new NetworkInfo(ni),
+        netId = cm.registerNetworkAgent(new Messenger(this), new NetworkInfo(ni),
                 new LinkProperties(lp), new NetworkCapabilities(nc), score, misc);
     }