sock转发 tcp端口转发

代码

import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Date;
import java.util.concurrent.CountDownLatch;

public class NAT extends Thread {
	private final Socket socket;
	private final InetSocketAddress target;

	public NAT(Socket socket, InetSocketAddress target) {
		this.socket = socket;
		this.target = target;
	}

	@Override
	public void run() {
		InputStream in = null, targetIn = null;
		OutputStream out = null, targetOut = null;
		Socket targetSocket = null;
		try {
			log("proxy %s to %s", socket.getInetAddress(),target);
			in = socket.getInputStream();
			out = socket.getOutputStream();
			targetSocket = new Socket(target.getAddress(), target.getPort());
			targetIn = targetSocket.getInputStream();
			targetOut = targetSocket.getOutputStream();
			CountDownLatch latch = new CountDownLatch(1);
			transfer(latch, in, targetOut);
			transfer(latch, targetIn, out);
			latch.await();
		} catch (Exception ignored) {
		} finally {
			closeIo(in);
			closeIo(out);
			closeIo(targetIn);
			closeIo(targetOut);
			closeIo(socket);
			closeIo(targetSocket);
		}

	}

	private static String LOG_FORMATTER = "%1$tF %1$tT %2$-3s %3$s%n";

	private static  void log(String message, Object... args) {
		Date dat = new Date();
		message = null == message ? " " : message;
		String data = args.length > 0 ? String.format(message, args) : message;
		Thread curr = Thread.currentThread();
		String msg = String.format(LOG_FORMATTER, dat, curr.getId(), data, curr.getName());
		System.out.print(msg);
	}

	/**
	 * 数据交换.主要用于tcp协议的交换
	 * 
	 * @createTime 2014年12月13日 下午11:06:47
	 * @param lock
	 *            锁
	 * @param in
	 *            输入流
	 * @param out
	 *            输出流
	 */
	public static void transfer(final CountDownLatch latch, final InputStream in, final OutputStream out) {
		new Thread() {
			public void run() {
				byte[] bytes = new byte[1024];
				int n;
				try {
					while ((n = in.read(bytes)) > 0) {
						out.write(bytes, 0, n);
						out.flush();
					}
				} catch (Exception ignored) {
				}
				if (null != latch) {
					latch.countDown();
				}
			};
		}.start();
	}

	private void closeIo(Closeable closeable) {
		if (null != closeable) {
			try {
				closeable.close();
			} catch (IOException ignored) {
			}
		}
	}

	public static void main(String[] args) throws IOException {
		String tmp = args.length > 0 ? args[0] : "53";
		int port = Integer.valueOf(tmp);
		tmp = args.length > 1 ? args[1] : "127.0.0.1";
		String targetHost = tmp;
		tmp = args.length > 1 ? args[2] : "1053";
		int targetPort = Integer.valueOf(tmp);
		log("proxy %s to %s:%s", port,targetHost,targetPort);
		InetSocketAddress net = new InetSocketAddress(targetHost, targetPort);
		ServerSocket sso = new ServerSocket(port);
		Socket socket = null;
		while (null != (socket = sso.accept())) {
			new NAT(socket, net).start();
		}
		sso.close();
	}
}