Socks4ProxySocketFactory.java

package org.jivesoftware.smack.proxy;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

import javax.net.SocketFactory;

/**
 * Socket factory for socks4 proxy
 * 
 * @author Atul Aggarwal
 */
public class Socks4ProxySocketFactory extends SocketFactory {
	private final ProxyInfo proxy;

	public Socks4ProxySocketFactory(ProxyInfo proxy) {
		this.proxy = proxy;
	}

	@Override
	public Socket createSocket(InetAddress host, int port) throws IOException {
		return socks4ProxifiedSocket(host.getHostAddress(), port);
	}

	@Override
	public Socket createSocket(InetAddress address, int port,
			InetAddress localAddress, int localPort) throws IOException {
		return socks4ProxifiedSocket(address.getHostAddress(), port);

	}

	@Override
	public Socket createSocket(String host, int port) throws IOException,
			UnknownHostException {
		return socks4ProxifiedSocket(host, port);

	}

	@Override
	public Socket createSocket(String host, int port, InetAddress localHost,
			int localPort) throws IOException, UnknownHostException {
		return socks4ProxifiedSocket(host, port);
	}

	private Socket socks4ProxifiedSocket(String host, int port)
			throws IOException {
		Socket socket = null;
		InputStream in = null;
		OutputStream out = null;
		final String proxy_host = proxy.getProxyAddress();
		final int proxy_port = proxy.getProxyPort();
		final String user = proxy.getProxyUsername();
		proxy.getProxyPassword();

		try {
			socket = new Socket(proxy_host, proxy_port);
			in = socket.getInputStream();
			out = socket.getOutputStream();
			socket.setTcpNoDelay(true);

			final byte[] buf = new byte[1024];
			int index = 0;

			/*
			 * 1) CONNECT
			 * 
			 * The client connects to the SOCKS server and sends a CONNECT
			 * request when it wants to establish a connection to an application
			 * server. The client includes in the request packet the IP address
			 * and the port number of the destination host, and userid, in the
			 * following format.
			 * 
			 * +----+----+----+----+----+----+----+----+----+----+....+----+ |
			 * VN | CD | DSTPORT | DSTIP | USERID |NULL|
			 * +----+----+----+----+----+----+----+----+----+----+....+----+ #
			 * of bytes: 1 1 2 4 variable 1
			 * 
			 * VN is the SOCKS protocol version number and should be 4. CD is
			 * the SOCKS command code and should be 1 for CONNECT request. NULL
			 * is a byte of all zero bits.
			 */

			index = 0;
			buf[index++] = 4;
			buf[index++] = 1;

			buf[index++] = (byte) (port >>> 8);
			buf[index++] = (byte) (port & 0xff);

			try {
				final InetAddress addr = InetAddress.getByName(host);
				final byte[] byteAddress = addr.getAddress();
				for (final byte byteAddres : byteAddress) {
					buf[index++] = byteAddres;
				}
			} catch (final UnknownHostException uhe) {
				throw new ProxyException(ProxyInfo.ProxyType.SOCKS4,
						uhe.toString(), uhe);
			}

			if (user != null) {
				System.arraycopy(user.getBytes(), 0, buf, index, user.length());
				index += user.length();
			}
			buf[index++] = 0;
			out.write(buf, 0, index);

			/*
			 * The SOCKS server checks to see whether such a request should be
			 * granted based on any combination of source IP address,
			 * destination IP address, destination port number, the userid, and
			 * information it may obtain by consulting IDENT, cf. RFC 1413. If
			 * the request is granted, the SOCKS server makes a connection to
			 * the specified port of the destination host. A reply packet is
			 * sent to the client when this connection is established, or when
			 * the request is rejected or the operation fails.
			 * 
			 * +----+----+----+----+----+----+----+----+ | VN | CD | DSTPORT |
			 * DSTIP | +----+----+----+----+----+----+----+----+ # of bytes: 1 1
			 * 2 4
			 * 
			 * VN is the version of the reply code and should be 0. CD is the
			 * result code with one of the following values:
			 * 
			 * 90: request granted 91: request rejected or failed 92: request
			 * rejected becasue SOCKS server cannot connect to identd on the
			 * client 93: request rejected because the client program and identd
			 * report different user-ids
			 * 
			 * The remaining fields are ignored.
			 */

			final int len = 6;
			int s = 0;
			while (s < len) {
				final int i = in.read(buf, s, len - s);
				if (i <= 0) {
					throw new ProxyException(ProxyInfo.ProxyType.SOCKS4,
							"stream is closed");
				}
				s += i;
			}
			if (buf[0] != 0) {
				throw new ProxyException(ProxyInfo.ProxyType.SOCKS4,
						"server returns VN " + buf[0]);
			}
			if (buf[1] != 90) {
				try {
					socket.close();
				} catch (final Exception eee) {
				}
				final String message = "ProxySOCKS4: server returns CD "
						+ buf[1];
				throw new ProxyException(ProxyInfo.ProxyType.SOCKS4, message);
			}
			final byte[] temp = new byte[2];
			in.read(temp, 0, 2);
			return socket;
		} catch (final RuntimeException e) {
			throw e;
		} catch (final Exception e) {
			try {
				if (socket != null) {
					socket.close();
				}
			} catch (final Exception eee) {
			}
			throw new ProxyException(ProxyInfo.ProxyType.SOCKS4, e.toString());
		}
	}
}