/*
* 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.directconnection.core;
import java.net.InetSocketAddress;
import java.net.Socket;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import de.fhkn.in.uce.directconnection.message.DirectconnectionAttribute;
import de.fhkn.in.uce.stun.attribute.Username;
import de.fhkn.in.uce.stun.attribute.XorMappedAddress;
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.MessageReader;
import de.fhkn.in.uce.stun.message.MessageStaticFactory;
/**
* Class to create a source-side direct connection. For that No NAT traversal
* technique is used.
*
* @author Alexander Diener (aldiener@htwg-konstanz.de)
*
*/
public final class DirectconnectionSource {
private static final Logger logger = LoggerFactory.getLogger(DirectconnectionSource.class);
/**
* Creates a {@link DirectconnectionSource} object.
*/
public DirectconnectionSource() {
super();
}
/**
* Establishes a source-side connection to the given target. The mediator is
* asked for the necessary endpoint.
*
* @param targetId
* the id of the target to connect
* @param controlConnection
* the control connection to the mediator
* @return the connected socket
* @throws Exception
*/
public Socket establishSourceSideConnection(final String targetId, final Socket controlConnection) throws Exception {
this.sendConnectionRequest(targetId, controlConnection);
final InetSocketAddress targetAddress = this.processConnectionRequestResponse(controlConnection);
logger.debug("Creating socket to {}", targetAddress.toString());
return this.createSocketToEndpoint(targetAddress, new InetSocketAddress(controlConnection.getLocalAddress(),
controlConnection.getLocalPort()));
}
private void sendConnectionRequest(final String targetId, final Socket controlConnection) throws Exception {
final Message requestConnectionMessage = MessageStaticFactory.newSTUNMessageInstance(STUNMessageClass.REQUEST,
STUNMessageMethod.CONNECTION_REQUEST);
requestConnectionMessage.addAttribute(new DirectconnectionAttribute());
requestConnectionMessage.addAttribute(new Username(targetId));
requestConnectionMessage.writeTo(controlConnection.getOutputStream());
}
private InetSocketAddress processConnectionRequestResponse(final Socket controlConnection) throws Exception {
InetSocketAddress result;
final MessageReader messageReader = MessageReader.createMessageReader();
final Message responseMessage = messageReader.readSTUNMessage(controlConnection.getInputStream());
if (responseMessage.hasAttribute(XorMappedAddress.class)) {
final XorMappedAddress xorMappedAddress = responseMessage.getAttribute(XorMappedAddress.class);
result = xorMappedAddress.getEndpoint();
} else {
throw new Exception("The target endpoint is not returned by the mediator"); //$NON-NLS-1$
}
return result;
}
private Socket createSocketToEndpoint(final InetSocketAddress targetAddress, final InetSocketAddress bindAddress)
throws Exception {
final Socket socket = new Socket();
socket.setReuseAddress(true);
socket.bind(bindAddress);
socket.connect(targetAddress);
return socket;
}
}