Make CaptivePortalLogin app exit if underlying Network disconnects.

The app is no longer useful if the underlying Network has disconnected
and could get in the way of another signing into another Network.

bug:17672087
Change-Id: I26e820444640975e7fd4dd73244f4d4f4b40cb5e

Author: JensenPaul

packages/CaptivePortalLogin/AndroidManifest.xml

@@ -20,6 +20,7 @@
     package="com.android.captiveportallogin" >
 
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 
     <application android:label="@string/app_name" >
         <activity

packages/CaptivePortalLogin/src/com/android/captiveportallogin/CaptivePortalLoginActivity.java

@@ -20,7 +20,10 @@
 import android.content.Intent;
 import android.graphics.Bitmap;
 import android.net.ConnectivityManager;
+import android.net.ConnectivityManager.NetworkCallback;
 import android.net.Network;
+import android.net.NetworkCapabilities;
+import android.net.NetworkRequest;
 import android.os.Bundle;
 import android.provider.Settings;
 import android.provider.Settings.Global;
@@ -55,6 +58,7 @@ public class CaptivePortalLoginActivity extends Activity {
 
     private URL mURL;
     private int mNetId;
+    private NetworkCallback mNetworkCallback;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -73,7 +77,27 @@ protected void onCreate(Bundle savedInstanceState) {
         getActionBar().setDisplayShowHomeEnabled(false);
 
         mNetId = Integer.parseInt(getIntent().getStringExtra(Intent.EXTRA_TEXT));
-        ConnectivityManager.setProcessDefaultNetwork(new Network(mNetId));
+        final Network network = new Network(mNetId);
+        ConnectivityManager.setProcessDefaultNetwork(network);
+
+        // Exit app if Network disappears.
+        final NetworkCapabilities networkCapabilities =
+                ConnectivityManager.from(this).getNetworkCapabilities(network);
+        if (networkCapabilities == null) {
+            finish();
+            return;
+        }
+        mNetworkCallback = new NetworkCallback() {
+            @Override
+            public void onLost(Network lostNetwork) {
+                if (network.equals(lostNetwork)) done(false);
+            }
+        };
+        final NetworkRequest.Builder builder = new NetworkRequest.Builder();
+        for (int transportType : networkCapabilities.getTransportTypes()) {
+            builder.addTransportType(transportType);
+        }
+        ConnectivityManager.from(this).registerNetworkCallback(builder.build(), mNetworkCallback);
 
         WebView myWebView = (WebView) findViewById(R.id.webview);
         WebSettings webSettings = myWebView.getSettings();
@@ -84,6 +108,7 @@ protected void onCreate(Bundle savedInstanceState) {
     }
 
     private void done(boolean use_network) {
+        ConnectivityManager.from(this).unregisterNetworkCallback(mNetworkCallback);
         Intent intent = new Intent(ACTION_CAPTIVE_PORTAL_LOGGED_IN);
         intent.putExtra(Intent.EXTRA_TEXT, String.valueOf(mNetId));
         intent.putExtra(LOGGED_IN_RESULT, use_network ? "1" : "0");