/*
* Copyright (c) 2012 Alexander Diener,
*
* This program is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* This program 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 General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
package de.fhkn.in.uce.reversal.core;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import de.fhkn.in.uce.reversal.message.ReversalAttribute;
import de.fhkn.in.uce.stun.attribute.Username;
import de.fhkn.in.uce.stun.header.STUNMessageClass;
import de.fhkn.in.uce.stun.header.STUNMessageMethod;
import de.fhkn.in.uce.stun.message.Message;
import de.fhkn.in.uce.stun.message.MessageStaticFactory;
/**
* Class that implements the source of the connection reversal.
*
* @author thomas zink, stefan lohr, Alexander Diener
* (aldiener@htwg-konstanz.de)
*/
public final class ReversalSource {
private static final Logger logger = LoggerFactory.getLogger(ReversalSource.class);
private final int socketTimeoutInMillis = 60 * 1000;
/**
* Creates a {@link ReversalSource} object.
*/
public ReversalSource() {
super();
}
/**
* Connects to the given target name and returns the according socket. A
* server socket is created which listens to incoming connections from the
* target. To initiate a connection, a connection request is sent over the
* control connection.
*
* @param uniqueUserName
* the name of the target
* @return the socket to the target
* @throws IOException
*/
public Socket establishSourceSideConnection(final String uniqueUserName, final Socket controlConnection)
throws IOException {
final ServerSocket serverSocket = this.createBoundServerSocket(uniqueUserName, controlConnection);
logger.info("listen on serverSocket {}", serverSocket); //$NON-NLS-1$
this.sendConnectionRequest(uniqueUserName, controlConnection);
final Socket socket = serverSocket.accept();
serverSocket.close();
return socket;
}
private ServerSocket createBoundServerSocket(final String uniqueUserName, final Socket controlConnection)
throws IOException {
final ServerSocket serverSocket = new ServerSocket();
serverSocket.setReuseAddress(true);
serverSocket.bind(new InetSocketAddress(controlConnection.getLocalAddress(), controlConnection.getLocalPort()));
serverSocket.setSoTimeout(this.socketTimeoutInMillis);
return serverSocket;
}
private void sendConnectionRequest(final String targetId, final Socket controlConnection) throws IOException {
final Message requestMessage = MessageStaticFactory.newSTUNMessageInstance(STUNMessageClass.REQUEST,
STUNMessageMethod.CONNECTION_REQUEST);
requestMessage.addAttribute(new Username(targetId));
requestMessage.addAttribute(new ReversalAttribute());
logger.info("send connection request for target {}", targetId); //$NON-NLS-1$
requestMessage.writeTo(controlConnection.getOutputStream());
}
}