Direct IP connect functionality for AppRTC Android demo.

webrtc/examples/androidapp/src/org/appspot/apprtc/TCPChannelClient.java

+/*
+ *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.appspot.apprtc;
+
+import android.util.Log;
+
+import org.appspot.apprtc.util.LooperExecutor;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.PrintWriter;
+import java.net.InetAddress;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.net.UnknownHostException;
+
+/**
+ * Replacement for WebSocketChannelClient for direct communication between two IP addresses. Handles
+ * the signaling between the two clients using a TCP connection.
+ *
+ * <p>All public methods should be called from a looper executor thread
+ * passed in a constructor, otherwise exception will be thrown.
+ * All events are dispatched on the same thread.
+ */
+public class TCPChannelClient {
+  private static final String TAG = "TCPChannelClient";
+
+  private final LooperExecutor executor;
+  private final TCPChannelEvents eventListener;
+  private TCPSocket socket;
+
+  /**
+   * Callback interface for messages delivered on TCP Connection. All callbacks are invoked from the
+   * looper executor thread.
+   */
+  public interface TCPChannelEvents {
+    void onTCPConnected(boolean server);
+    void onTCPMessage(String message);
+    void onTCPError(String description);
+    void onTCPClose();
+  }
+
+  /**
+   * Initializes the TCPChannelClient. If IP is a local IP address, starts a listening server on
+   * that IP. If not, instead connects to the IP.
+   *
+   * @param eventListener Listener that will receive events from the client.
+   * @param ip IP address to listen on or connect to.
+   * @param port Port to listen on or connect to.
+   */
+  public TCPChannelClient(
+          LooperExecutor executor, TCPChannelEvents eventListener, String ip, int port) {
+    this.executor = executor;
+    this.eventListener = eventListener;
+
+    InetAddress address;
+    try {
+      address = InetAddress.getByName(ip);
+    } catch (UnknownHostException e) {
+      reportError("Invalid IP address.");
+      return;
+    }
+
+    if (address.isAnyLocalAddress()) {
+      socket = new TCPSocketServer(address, port);
+    } else {
+      socket = new TCPSocketClient(address, port);
+    }
+
+    socket.start();
+  }
+
+  /**
+   * Disconnects the client if not already disconnected. This will fire the onTCPClose event.
+   */
+  public void disconnect() {
+    checkIfCalledOnValidThread();
+
+    socket.disconnect();
+  }
+
+  /**
+   * Sends a message on the socket.
+   *
+   * @param message Message to be sent.
+   */
+  public void send(String message) {
+    checkIfCalledOnValidThread();
+
+    socket.send(message);
+  }
+
+  /**
+   * Helper method for firing onTCPError events. Calls onTCPError on the executor thread.
+   */
+  private void reportError(final String message) {
+    executor.execute(new Runnable() {
+      @Override
+      public void run() {
+        eventListener.onTCPError(message);
+      }
+    });
+  }
+
+  /**
+   * Helper method for debugging purposes.
+   * Ensures that TCPChannelClient method is called on a looper thread.
+   */
+  private void checkIfCalledOnValidThread() {
+    if (!executor.checkOnLooperThread()) {
+      throw new IllegalStateException(
+              "TCPChannelClient method is not called on valid thread");
+    }
+  }
+
+
+  /**
+   * Base class for server and client sockets. Contains a listening thread that will call
+   * eventListener.onTCPMessage on new messages.
+   */
+  private abstract class TCPSocket extends Thread {
+    // Lock for editing out and rawSocket
+    protected final Object rawSocketLock;
+    private PrintWriter out;
+    private Socket rawSocket;
+
+    /**
+     * Connect to the peer, potentially a slow operation.
+     *
+     * @return Socket connection, null if connection failed.
+     */
+    public abstract Socket connect();
+    /** Returns true if sockets is a server rawSocket. */
+    public abstract boolean isServer();
+
+    TCPSocket() {
+      rawSocketLock = new Object();
+    }
+
+    /**
+     * The listening thread.
+     */
+    @Override
+    public void run() {
+      // Receive connection to temporary variable first, so we don't block
+      Socket tempSocket = connect();
+      BufferedReader in;
+
+      synchronized (rawSocketLock) {
+        if (rawSocket != null) {
+          Log.e(TAG, "Socket already existed and will be replaced.");
+        }
+
+        rawSocket = tempSocket;
+
+        // Connecting failed, error has already been reported, just exit
+        if (rawSocket == null) {
+          return;
+        }
+
+        try {
+          out = new PrintWriter(rawSocket.getOutputStream(), true);
+          in = new BufferedReader(new InputStreamReader(rawSocket.getInputStream()));
+        } catch (IOException e) {
+          reportError("Failed to open IO on rawSocket: " + e.getMessage());
+          return;
+        }
+      }
+
+      executor.execute(new Runnable() {
+        @Override
+        public void run() {
+          eventListener.onTCPConnected(isServer());
+        }
+      });
+
+      String message;
+      while (true) {
+        try {
+          message = in.readLine();
+        } catch (IOException e) {
+          reportError("Failed to read from rawSocket: " + e.getMessage());
+          return;

[magjed_webrtc, 2016/05/10 14:50:02]

break instead of return?

[sakal, 2016/05/11 08:38:50]

Yep, you're right.

+        }
+
+        // No data received, rawSocket probably closed
+        if (message == null) {
+          break;
+        }
+
+        // We need final variable for the Runnable
+        final String executorMessage = message;

[magjed_webrtc, 2016/05/10 14:50:03]

Move declaration of |message| inside while loop and make it final, and remove
|executorMessage|.

[sakal, 2016/05/11 08:38:50]

Done.

+        executor.execute(new Runnable() {
+          @Override
+          public void run() {
+            Log.v(TAG, "Receive: " + executorMessage);
+            eventListener.onTCPMessage(executorMessage);
+          }
+        });
+      }
+
+      Log.d(TAG, "Receiving thread exiting...");
+
+      // Close the rawSocket if it is still open
+      disconnect();
+    }
+
+    /**
+     * Closes the rawSocket if it is still open. Also fires the onTCPClose event.
+     */
+    public void disconnect() {
+      try {
+        synchronized (rawSocketLock) {
+          if (rawSocket != null) {
+            rawSocket.close();
+            rawSocket = null;
+            out = null;
+
+            eventListener.onTCPClose();
+          }
+        }
+      } catch (IOException e) {

[magjed_webrtc, 2016/05/10 14:50:03]

Catch just rawSocket.close() so that eventListener.onTCPClose() is called
regardless if rawSocket.close() fails or not?

[sakal, 2016/05/11 08:38:50]

This is something I thought about. eventListener.onTCPClose() will just cause
the call to end with message "Remote end hung up; dropping PeerConnection".
eventListener.onTCPError() causes a dialog to be shown with the error and OK
ends the call. Do we want both to happen?

[magjed_webrtc, 2016/05/11 11:22:55]

Probably not. Then the code is good as it is.

+        reportError("Failed to close rawSocket: " + e.getMessage());
+      }
+    }
+
+    /**
+     * Sends a message on the socket. Should only be called on the executor thread.
+     *
+     * @param message
+     */
+    public void send(String message) {
+      Log.v(TAG, "Send: " + message);
+
+      synchronized (rawSocketLock) {
+        if (out == null) {
+          Log.e(TAG, "Sending data on closed socket.");

[magjed_webrtc, 2016/05/10 14:50:03]

You need to return here, otherwise it will crash on the next line.

[sakal, 2016/05/11 08:38:50]

Correct, fixed. Also changed this to reportError because this is a quite
critical error that should probably end the call.

+        }
+
+        out.write(message + "\n");
+        out.flush();
+      }
+    }
+  }
+
+  private class TCPSocketServer extends TCPSocket {
+    // Server socket also guarded by rawSocketLock
+    private ServerSocket serverSocket;
+
+    private InetAddress address;

[magjed_webrtc, 2016/05/10 14:50:03]

Make these variables final.

[sakal, 2016/05/11 08:38:50]

Done.

+    private int port;
+
+    public TCPSocketServer(InetAddress address, int port) {
+      this.address = address;
+      this.port = port;
+    }
+
+    /** Opens a listening socket and waits for a connection. */
+    public Socket connect() {
+      Log.d(TAG, "Listening on " + address.getHostAddress() + ":" + Integer.toString(port));
+
+      synchronized (rawSocketLock) {
+        if (serverSocket != null) {
+          Log.e(TAG, "Server rawSocket was already listening and new will be opened.");
+        }
+
+        try {
+          serverSocket = new ServerSocket(port, 0, address);
+          return serverSocket.accept();
+        } catch (IOException e) {
+          reportError("Failed to receive connection: " + e.getMessage());
+          return null;
+        }
+      }
+    }
+
+    /** Closes the listening socket and calls super. */
+    @Override
+    public void disconnect() {
+      try {
+        synchronized (rawSocketLock) {
+          if (serverSocket != null) {
+            serverSocket.close();
+            serverSocket = null;
+          }
+        }
+      } catch (IOException e) {
+        reportError("Failed to close server socket: " + e.getMessage());
+      }
+
+      super.disconnect();
+    }
+
+    public boolean isServer() {

[magjed_webrtc, 2016/05/10 14:50:03]

add @Override?

[sakal, 2016/05/11 08:38:50]

Done.

+      return true;
+    }
+  }
+
+  private class TCPSocketClient extends TCPSocket {
+    private InetAddress address;

[magjed_webrtc, 2016/05/10 14:50:02]

Make these variables final.

[sakal, 2016/05/11 08:38:50]

Done.

+    private int port;
+
+    public TCPSocketClient(InetAddress address, int port) {
+      this.address = address;
+      this.port = port;
+    }
+
+    /** Connects to the peer. */
+    public Socket connect() {

[magjed_webrtc, 2016/05/10 14:50:03]

add @Override?

[sakal, 2016/05/11 08:38:50]

Done.

+      Log.d(TAG, "Connecting to [" + address.getHostAddress() + "]:" + Integer.toString(port));
+
+      try {
+        return new Socket(address, port);
+      } catch (IOException e) {
+        reportError("Failed to connect: " + e.getMessage());
+        return null;
+      }
+    }
+
+    public boolean isServer() {

[magjed_webrtc, 2016/05/10 14:50:03]

add @Override?

[sakal, 2016/05/11 08:38:50]

Done.

+      return false;
+    }
+  }
+}