Added support for VPN Proxy

src/main/AndroidManifest.xml

@@ -97,6 +97,12 @@
                 android:name="android.app.searchable"
                 android:resource="@xml/searchable" />
         </activity>
+        <service android:name=".activity.ServerFilesActivity"
+            android:permission="android.permission.BIND_VPN_SERVICE">
+            <intent-filter>
+                <action android:name="android.net.VpnService"/>
+            </intent-filter>
+        </service>
         <activity
             android:name=".activity.ServerFileAudioActivity"
             android:launchMode="singleTop"

src/main/java/org/amahi/anywhere/util/VpnProxyTunnel.java

@@ -0,0 +1,90 @@
+package org.amahi.anywhere.util;
+
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.content.Intent;
+import android.net.VpnService;
+import android.os.Handler;
+import android.os.Message;
+import android.os.ParcelFileDescriptor;
+import android.util.Log;
+import android.util.Pair;
+import android.widget.Toast;
+
+import org.amahi.anywhere.activity.AuthenticationActivity;
+
+import java.io.IOException;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+public class VpnProxyTunnel extends VpnService implements Handler.Callback {
+    private static final String TAG = VpnProxyTunnel.class.getSimpleName();
+    public static final String ACTION_CONNECT = "com.example.android.toyvpn.START";
+    public static final String ACTION_DISCONNECT = "com.example.android.toyvpn.STOP";
+    private Handler mHandler;
+    private static class Connection extends Pair<Thread, ParcelFileDescriptor> {
+        public Connection(Thread thread, ParcelFileDescriptor pfd) {
+            super(thread, pfd);
+        }
+    }
+    private final AtomicReference<Thread> mConnectingThread = new AtomicReference<>();
+    private final AtomicReference<Connection> mConnection = new AtomicReference<>();
+    private AtomicInteger mNextConnectionId = new AtomicInteger(1);
+    private PendingIntent mConfigureIntent;
+    @Override
+    public void onCreate() {
+        // The handler is only used to show messages.
+        if (mHandler == null) {
+            mHandler = new Handler(this);
+        }
+        // Create the intent to "configure" the connection (just start ToyVpnClient).
+        mConfigureIntent = PendingIntent.getActivity(this, 0, new Intent(this, AuthenticationActivity.class),
+            PendingIntent.FLAG_UPDATE_CURRENT);
+    }
+    @Override
+    public int onStartCommand(Intent intent, int flags, int startId) {
+        if (intent != null && ACTION_DISCONNECT.equals(intent.getAction())) {
+            disconnect();
+            return START_NOT_STICKY;
+        } else {
+            return START_STICKY;
+        }
+    }
+    @Override
+    public void onDestroy() {
+        disconnect();
+    }
+    @Override
+    public boolean handleMessage(Message message) {
+        Toast.makeText(this, message.what, Toast.LENGTH_SHORT).show();
+
+        return true;
+    }
+
+    private void setConnectingThread(final Thread thread) {
+        final Thread oldThread = mConnectingThread.getAndSet(thread);
+        if (oldThread != null) {
+            oldThread.interrupt();
+        }
+    }
+    private void setConnection(final Connection connection) {
+        final Connection oldConnection = mConnection.getAndSet(connection);
+        if (oldConnection != null) {
+            try {
+                oldConnection.first.interrupt();
+                oldConnection.second.close();
+            } catch (IOException e) {
+                Log.e(TAG, "Closing VPN interface", e);
+            }
+        }
+    }
+    private void disconnect() {
+        setConnectingThread(null);
+        setConnection(null);
+        stopForeground(true);
+    }
+    private void updateForegroundNotification(final int message) {
+        final String NOTIFICATION_CHANNEL_ID = "ToyVpn";
+        NotificationManager mNotificationManager = (NotificationManager) getSystemService(
+            NOTIFICATION_SERVICE);
+    }
+}