Java tutorial
/****************************************************************************** * * Copyright 2011-2012 Tavendo GmbH * * 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.pbi.dvb.websocket; import java.io.IOException; import java.net.SocketException; import java.nio.channels.SocketChannel; import java.util.Random; import org.apache.http.NameValuePair; import android.os.Handler; import android.os.Looper; import android.os.Message; import android.util.Base64; import android.util.Log; /** * WebSocket writer, the sending leg of a WebSockets connection. * This is run on it's background thread with it's own message loop. * The only method that needs to be called (from foreground thread) is forward(), * which is used to forward a WebSockets message to this object (running on * background thread) so that it can be formatted and sent out on the * underlying TCP socket. */ public class WebSocketWriter extends Handler { private static final boolean DEBUG = true; private static final String TAG = WebSocketWriter.class.getName(); /// Random number generator for handshake key and frame mask generation. private final Random mRng = new Random(); /// Connection master. private final Handler mMaster; /// Message looper this object is running on. private final Looper mLooper; /// The NIO socket channel created on foreground thread. private final SocketChannel mSocket; /// WebSockets options. private final WebSocketOptions mOptions; /// The send buffer that holds data to send on socket. private final ByteBufferOutputStream mBuffer; /** * Create new WebSockets background writer. * * @param looper The message looper of the background thread on which * this object is running. * @param master The message handler of master (foreground thread). * @param socket The socket channel created on foreground thread. * @param options WebSockets connection options. */ public WebSocketWriter(Looper looper, Handler master, SocketChannel socket, WebSocketOptions options) { super(looper); mLooper = looper; mMaster = master; mSocket = socket; mOptions = options; mBuffer = new ByteBufferOutputStream(options.getMaxFramePayloadSize() + 14, 4 * 64 * 1024); if (DEBUG) Log.d(TAG, "created"); } /** * Call this from the foreground (UI) thread to make the writer * (running on background thread) send a WebSocket message on the * underlying TCP. * * @param message Message to send to WebSockets writer. An instance of the message * classes inside WebSocketMessage or another type which then needs * to be handled within processAppMessage() (in a class derived from * this class). */ public void forward(Object message) { Message msg = obtainMessage(); msg.obj = message; sendMessage(msg); } /** * Notify the master (foreground thread). * * @param message Message to send to master. */ private void notify(Object message) { Message msg = mMaster.obtainMessage(); msg.obj = message; mMaster.sendMessage(msg); } /** * Create new key for WebSockets handshake. * * @return WebSockets handshake key (Base64 encoded). */ public String newHandshakeKey() { final byte[] ba = new byte[16]; mRng.nextBytes(ba); return Base64.encodeToString(ba, Base64.NO_WRAP); } /** * Create new (random) frame mask. * * @return Frame mask (4 octets). */ private byte[] newFrameMask() { final byte[] ba = new byte[4]; mRng.nextBytes(ba); return ba; } /** * Send WebSocket client handshake. */ private void sendClientHandshake(WebSocketMessage.ClientHandshake message) throws IOException { // write HTTP header with handshake String path; if (message.mQuery != null) { path = message.mPath + "?" + message.mQuery; } else { path = message.mPath; } mBuffer.write("GET " + path + " HTTP/1.1"); mBuffer.crlf(); mBuffer.write("Host: " + message.mHost); mBuffer.crlf(); mBuffer.write("Upgrade: WebSocket"); mBuffer.crlf(); mBuffer.write("Connection: Upgrade"); mBuffer.crlf(); if (message.mHandshakeKey != null) mBuffer.write("Sec-WebSocket-Key: " + message.mHandshakeKey); else mBuffer.write("Sec-WebSocket-Key: " + newHandshakeKey()); mBuffer.crlf(); if (message.mOrigin != null && !message.mOrigin.equals("")) { mBuffer.write("Origin: " + message.mOrigin); mBuffer.crlf(); } if (message.mSubprotocols != null && message.mSubprotocols.length > 0) { mBuffer.write("Sec-WebSocket-Protocol: "); for (int i = 0; i < message.mSubprotocols.length; ++i) { mBuffer.write(message.mSubprotocols[i]); mBuffer.write(", "); } mBuffer.crlf(); } mBuffer.write("Sec-WebSocket-Version: 13"); mBuffer.crlf(); // Header injection if (message.mHeaderList != null) { for (NameValuePair pair : message.mHeaderList) { mBuffer.write(pair.getName() + ":" + pair.getValue()); mBuffer.crlf(); } } mBuffer.crlf(); } /** * Send WebSockets close. */ private void sendClose(WebSocketMessage.Close message) throws IOException, WebSocketException { if (message.mCode > 0) { byte[] payload = null; if (message.mReason != null && !message.mReason.equals("")) { byte[] pReason = message.mReason.getBytes("UTF-8"); payload = new byte[2 + pReason.length]; for (int i = 0; i < pReason.length; ++i) { payload[i + 2] = pReason[i]; } } else { payload = new byte[2]; } if (payload != null && payload.length > 125) { throw new WebSocketException("close payload exceeds 125 octets"); } payload[0] = (byte) ((message.mCode >> 8) & 0xff); payload[1] = (byte) (message.mCode & 0xff); sendFrame(8, true, payload); } else { sendFrame(8, true, null); } } /** * Send WebSockets ping. */ private void sendPing(WebSocketMessage.Ping message) throws IOException, WebSocketException { if (message.mPayload != null && message.mPayload.length > 125) { throw new WebSocketException("ping payload exceeds 125 octets"); } sendFrame(9, true, message.mPayload); } /** * Send WebSockets pong. Normally, unsolicited Pongs are not used, * but Pongs are only send in response to a Ping from the peer. */ private void sendPong(WebSocketMessage.Pong message) throws IOException, WebSocketException { if (message.mPayload != null && message.mPayload.length > 125) { throw new WebSocketException("pong payload exceeds 125 octets"); } sendFrame(10, true, message.mPayload); } /** * Send WebSockets binary message. */ private void sendBinaryMessage(WebSocketMessage.BinaryMessage message) throws IOException, WebSocketException { if (message.mPayload.length > mOptions.getMaxMessagePayloadSize()) { throw new WebSocketException("message payload exceeds payload limit"); } sendFrame(2, true, message.mPayload); } /** * Send WebSockets text message. */ private void sendTextMessage(WebSocketMessage.TextMessage message) throws IOException, WebSocketException { byte[] payload = message.mPayload.getBytes("UTF-8"); if (payload.length > mOptions.getMaxMessagePayloadSize()) { throw new WebSocketException("message payload exceeds payload limit"); } sendFrame(1, true, payload); } /** * Send WebSockets binary message. */ private void sendRawTextMessage(WebSocketMessage.RawTextMessage message) throws IOException, WebSocketException { if (message.mPayload.length > mOptions.getMaxMessagePayloadSize()) { throw new WebSocketException("message payload exceeds payload limit"); } sendFrame(1, true, message.mPayload); } /** * Sends a WebSockets frame. Only need to use this method in derived classes which implement * more message types in processAppMessage(). You need to know what you are doing! * * @param opcode The WebSocket frame opcode. * @param fin FIN flag for WebSocket frame. * @param payload Frame payload or null. */ protected void sendFrame(int opcode, boolean fin, byte[] payload) throws IOException { if (payload != null) { sendFrame(opcode, fin, payload, 0, payload.length); } else { sendFrame(opcode, fin, null, 0, 0); } } /** * Sends a WebSockets frame. Only need to use this method in derived classes which implement * more message types in processAppMessage(). You need to know what you are doing! * * @param opcode The WebSocket frame opcode. * @param fin FIN flag for WebSocket frame. * @param payload Frame payload or null. * @param offset Offset within payload of the chunk to send. * @param length Length of the chunk within payload to send. */ protected void sendFrame(int opcode, boolean fin, byte[] payload, int offset, int length) throws IOException { // first octet byte b0 = 0; if (fin) { b0 |= (byte) (1 << 7); } b0 |= (byte) opcode; mBuffer.write(b0); // second octet byte b1 = 0; if (mOptions.getMaskClientFrames()) { b1 = (byte) (1 << 7); } long len = length; // extended payload length if (len <= 125) { b1 |= (byte) len; mBuffer.write(b1); } else if (len <= 0xffff) { b1 |= (byte) (126 & 0xff); mBuffer.write(b1); mBuffer.write(new byte[] { (byte) ((len >> 8) & 0xff), (byte) (len & 0xff) }); } else { b1 |= (byte) (127 & 0xff); mBuffer.write(b1); mBuffer.write(new byte[] { (byte) ((len >> 56) & 0xff), (byte) ((len >> 48) & 0xff), (byte) ((len >> 40) & 0xff), (byte) ((len >> 32) & 0xff), (byte) ((len >> 24) & 0xff), (byte) ((len >> 16) & 0xff), (byte) ((len >> 8) & 0xff), (byte) (len & 0xff) }); } byte mask[] = null; if (mOptions.getMaskClientFrames()) { // a mask is always needed, even without payload mask = newFrameMask(); mBuffer.write(mask[0]); mBuffer.write(mask[1]); mBuffer.write(mask[2]); mBuffer.write(mask[3]); } if (len > 0) { if (mOptions.getMaskClientFrames()) { /// \todo optimize masking /// \todo masking within buffer of output stream for (int i = 0; i < len; ++i) { payload[i + offset] ^= mask[i % 4]; } } mBuffer.write(payload, offset, length); } } /** * Process message received from foreground thread. This is called from * the message looper set up for the background thread running this writer. * * @param msg Message from thread message queue. */ @Override public void handleMessage(Message msg) { try { // clear send buffer mBuffer.clear(); // process message from master processMessage(msg.obj); // send out buffered data mBuffer.flip(); while (mBuffer.remaining() > 0) { // this can block on socket write @SuppressWarnings("unused") int written = mSocket.write(mBuffer.getBuffer()); } } catch (SocketException e) { if (DEBUG) Log.d(TAG, "run() : SocketException (" + e.toString() + ")"); // wrap the exception and notify master notify(new WebSocketMessage.ConnectionLost()); } catch (Exception e) { if (DEBUG) e.printStackTrace(); // wrap the exception and notify master notify(new WebSocketMessage.Error(e)); } } /** * Process WebSockets or control message from master. Normally, * there should be no reason to override this. If you do, you * need to know what you are doing. * * @param msg An instance of the message types within WebSocketMessage * or a message that is handled in processAppMessage(). */ protected void processMessage(Object msg) throws IOException, WebSocketException { if (msg instanceof WebSocketMessage.TextMessage) { sendTextMessage((WebSocketMessage.TextMessage) msg); } else if (msg instanceof WebSocketMessage.RawTextMessage) { sendRawTextMessage((WebSocketMessage.RawTextMessage) msg); } else if (msg instanceof WebSocketMessage.BinaryMessage) { sendBinaryMessage((WebSocketMessage.BinaryMessage) msg); } else if (msg instanceof WebSocketMessage.Ping) { sendPing((WebSocketMessage.Ping) msg); } else if (msg instanceof WebSocketMessage.Pong) { sendPong((WebSocketMessage.Pong) msg); } else if (msg instanceof WebSocketMessage.Close) { sendClose((WebSocketMessage.Close) msg); } else if (msg instanceof WebSocketMessage.ClientHandshake) { sendClientHandshake((WebSocketMessage.ClientHandshake) msg); } else if (msg instanceof WebSocketMessage.Quit) { mLooper.quit(); if (DEBUG) Log.d(TAG, "ended"); return; } else { // call hook which may be overridden in derived class to process // messages we don't understand in this class processAppMessage(msg); } } /** * Process message other than plain WebSockets or control message. * This is intended to be overridden in derived classes. * * @param msg Message from foreground thread to process. */ protected void processAppMessage(Object msg) throws WebSocketException, IOException { throw new WebSocketException("unknown message received by WebSocketWriter"); } }