/***************************************************************************
* Copyright 2006-2016 by Christian Ihle *
* contact@kouchat.net *
* *
* This file is part of KouChat. *
* *
* KouChat is free software; you can redistribute it and/or modify *
* it under the terms of the GNU Lesser General Public License as *
* published by the Free Software Foundation, either version 3 of *
* the License, or (at your option) any later version. *
* *
* KouChat is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with KouChat. *
* If not, see <http://www.gnu.org/licenses/>. *
***************************************************************************/
package net.usikkert.kouchat.net;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.net.NetworkInterface;
import java.util.logging.Level;
import java.util.logging.Logger;
import net.usikkert.kouchat.Constants;
import net.usikkert.kouchat.event.ReceiverListener;
import net.usikkert.kouchat.misc.ErrorHandler;
import net.usikkert.kouchat.util.Validate;
/**
* This is the thread that listens for multicast messages from
* the network, and notifies any listeners when messages arrive.
*
* @author Christian Ihle
*/
public class MessageReceiver implements Runnable {
/** The logger. */
private static final Logger LOG = Logger.getLogger(MessageReceiver.class.getName());
/** The multicast socket used for receiving messages. */
private MulticastSocket mcSocket;
/** The inetaddress object with the multicast ip address to receive messages from. */
private InetAddress address;
/** The listener getting all the messages received here. */
private ReceiverListener listener;
/** If connected to the network or not. */
private boolean connected;
/** The background thread watching for messages from the network. */
private Thread worker;
/** The port to receive messages on. */
private final int port;
/**
* Default constructor.
*
* <p>Initializes the network with the default ip address and port.</p>
*
* @see Constants#NETWORK_IP
* @see Constants#NETWORK_CHAT_PORT
* @param errorHandler The error handler to use.
*/
public MessageReceiver(final ErrorHandler errorHandler) {
this(Constants.NETWORK_IP, Constants.NETWORK_CHAT_PORT, errorHandler);
}
/**
* Alternative constructor.
*
* <p>Initializes the network with the given ip address and port.</p>
*
* @param ipAddress Multicast ip address to connect to.
* @param port Port to connect to.
* @param errorHandler The error handler to use.
*/
public MessageReceiver(final String ipAddress, final int port, final ErrorHandler errorHandler) {
LOG.fine("Creating MessageReceiver on " + ipAddress + ":" + port);
Validate.notEmpty(ipAddress, "IP address can not be empty");
Validate.notNull(errorHandler, "Error handler can not be null");
this.port = port;
try {
address = InetAddress.getByName(ipAddress);
}
catch (final IOException e) {
LOG.log(Level.SEVERE, e.toString(), e);
errorHandler.showCriticalError("Failed to initialize the network:\n" + e + "\n" +
Constants.APP_NAME + " will now shutdown.");
System.exit(1);
}
}
/**
* Waits for incoming packets, and notifies the listener when they arrive.
*/
public void run() {
while (connected) {
try {
final DatagramPacket packet = new DatagramPacket(
new byte[Constants.NETWORK_PACKET_SIZE], Constants.NETWORK_PACKET_SIZE);
if (connected) {
mcSocket.receive(packet);
final String ip = packet.getAddress().getHostAddress();
final String message = new String(packet.getData(), Constants.MESSAGE_CHARSET).trim();
LOG.log(Level.FINE, "Message arrived from " + ip + ": " + message);
if (listener != null) {
listener.messageArrived(message, ip);
}
}
}
// Happens when socket is closed, or network is down
catch (final IOException e) {
if (connected) {
LOG.log(Level.WARNING, e.toString());
}
else {
LOG.log(Level.FINE, e.toString());
}
}
}
}
/**
* Starts the thread that listens for messages.
*/
private void startThread() {
LOG.log(Level.FINE, "Starting.");
worker = new Thread(this, "MessageReceiverWorker");
worker.start();
}
/**
* Connects to the network with the given network interface, or gives
* the control to the operating system to choose if <code>null</code>
* is given.
*
* <p>Will also start a thread to continuously receive messages.</p>
*
* @param networkInterface The network interface to use, or <code>null</code>.
* @return If connected to the network or not.
*/
public synchronized boolean startReceiver(final NetworkInterface networkInterface) {
LOG.log(Level.FINE, "Connecting to " + address.getHostAddress() + ":" + port + " on " + networkInterface);
try {
if (connected) {
LOG.log(Level.FINE, "Already connected.");
}
else {
if (mcSocket == null) {
mcSocket = new MulticastSocket(port);
}
if (networkInterface != null) {
mcSocket.setNetworkInterface(networkInterface);
}
mcSocket.joinGroup(address);
LOG.log(Level.FINE, "Connected to " + mcSocket.getNetworkInterface());
connected = true;
}
}
catch (final IOException e) {
LOG.log(Level.SEVERE, "Could not start receiver: " + e.toString(), e);
if (mcSocket != null) {
if (!mcSocket.isClosed()) {
mcSocket.close();
}
mcSocket = null;
}
}
if (connected && (worker == null || !worker.isAlive())) {
startThread();
}
return connected;
}
/**
* Disconnects from the network and closes the multicast socket.
*/
public synchronized void stopReceiver() {
LOG.log(Level.FINE, "Disconnecting from " + address.getHostAddress() + ":" + port);
if (!connected) {
LOG.log(Level.FINE, "Not connected.");
}
else {
connected = false;
try {
if (!mcSocket.isClosed()) {
mcSocket.leaveGroup(address);
}
}
catch (final IOException e) {
LOG.log(Level.WARNING, e.toString());
}
if (!mcSocket.isClosed()) {
mcSocket.close();
mcSocket = null;
}
LOG.log(Level.FINE, "Disconnected from " + address.getHostAddress() + ":" + port);
}
}
/**
* Registers as the listener to receive all the messages from
* the network.
*
* @param listener The listener to register.
*/
public void registerReceiverListener(final ReceiverListener listener) {
this.listener = listener;
}
}