Socks5DatagramSocket.java

/*
 * Copyright 2015-2025 the original author or authors.
 * 
 * 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 sockslib.client;

import sockslib.common.Socks5DatagramPacketHandler;
import sockslib.common.SocksException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.InetSocketAddress;

/**
 * The class <code>Socks5DatagramSocket</code> is a DatagramSocket that support SOCKS5 proxy.<br>
 * For example:<br>
 * <pre>
 * SocksProxy proxy = new Socks5(new InetSocketAddress("foo.com", 1080));
 * // Setting proxy...
 * DatagramSocket client = new Socks5DatagramSocket(proxy);
 * // Just use it as normal java.net.DatagramSocket now.
 * </pre>
 *
 * @author Youchao Feng
 * @version 1.0
 * @date Mar 23, 2015 5:54:37 PM
 */
public class Socks5DatagramSocket extends DatagramSocket {

  /**
   * logger that subclasses also can use.
   */
  protected static final Logger logger = LoggerFactory.getLogger(Socks5DatagramSocket.class);

  /**
   * SOCKS proxy.
   */
  private SocksProxy proxy;

  /**
   * Relay server's IP address.
   */
  private InetAddress relayServerInetAddress;

  /**
   * Relay server's port which listens UDP connection.
   */
  private int relayServerPort;

  private Socks5DatagramPacketHandler datagramPacketHandler = new Socks5DatagramPacketHandler();

  /**
   * Constructs a datagram socket with a {@link SocksProxy}. <br>
   * <b>Notice:</b> The proxy must be {@link Socks5}, because only SOCKS5 protocol supports UDP
   * ASSOCIATE. It will throw {@link SocksException} if you give other {@link SocksProxy}
   * implementation which not supports SOCKS5 protocol.
   *
   * @param proxy {@link Socks5} instance.
   * @throws SocksException If any error about SOCKS protocol occurs.
   * @throws IOException    If any I/O error occurs.
   * @see <a href="http://www.ietf.org/rfc/rfc1928.txt">SOCKS Protocol Version 5</a>
   */
  public Socks5DatagramSocket(SocksProxy proxy) throws SocksException, IOException {
    super();
    this.proxy = proxy.copy();
    if (this.proxy.getChainProxy() != null) {
      throw new SocksException("Proxy chain not support UDP ASSOCIATE");
    }
    if (!(this.proxy instanceof Socks5)) {
      throw new SocksException("Only SOCKS5 protocol support UDP ASSOCIATE");
    }
    this.proxy.buildConnection();
    CommandReplyMessage message =
        this.proxy.requestUdpAssociate(this.getLocalAddress(), this.getLocalPort());

    logger.debug("build datagram socket at[{}:{}]", this.getLocalAddress(), this.getLocalPort());
    this.relayServerInetAddress = message.getIp();
    this.relayServerPort = message.getPort();

    logger.info("relay server's address[{}:{}]", relayServerInetAddress, relayServerPort);
  }


  @Override
  public void send(DatagramPacket packet) throws SocksException, IOException {
    super.send(datagramPacketHandler.encapsulate(packet, new InetSocketAddress
        (relayServerInetAddress, relayServerPort)));
  }

  @Override
  public synchronized void receive(DatagramPacket packet) throws SocksException, IOException {
    super.receive(packet);
    datagramPacketHandler.decapsulate(packet);
  }

  @Override
  public void close() {
    super.close();
    // Close TCP connection.
    try {
      if (!proxy.getProxySocket().isClosed()) {
        proxy.getProxySocket().close();
      }
    } catch (IOException e) {
      logger.error(e.getMessage(), e);
    }
  }

  public SocksProxy getProxy() {
    return proxy;
  }

  public void setProxy(SocksProxy proxy) {
    this.proxy = proxy;
  }


}