package org.wamblee.socketproxy;

/*
 * Created on Apr 5, 2005
 */

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * @author erik
 * 
 * TODO To change the template for this generated type comment go to Window -
 * Preferences - Java - Code Style - Code Templates
 */
public class SocketProxy {

    public static void main( final String[] args ) throws IOException {
        for ( int i = 0; i < args.length; i++ ) {
            // System.out.println(i + " " + args[i]);
            String[] fields = args[i].split( ":" );
            final int localPort = Integer.parseInt( fields[0] );
            final String host = fields[1];
            final int remotePort = Integer.parseInt( fields[2] );
            runSocketProxy( localPort, host, remotePort );
        }
    }

    /**
     * @param localPort
     * @param host
     * @param remotePort
     */
    private static void runSocketProxy( final int localPort,
            final String host, final int remotePort ) {
        new Thread( new Runnable( ) {
            public void run( ) {
                try {
                    new SocketProxy( localPort, host, remotePort );
                } catch ( IOException e ) {
                    System.out.println( "Problem with socket " + localPort
                            + ":" + host + ":" + remotePort );
                    e.printStackTrace( );
                }
            }
        } ).start( );
    }

    public SocketProxy( int localPort, String remoteHost, int remotePort )
            throws IOException {        
        System.out.println( "Listening on port " + localPort );
        ServerSocket server = new ServerSocket( localPort );
        for ( ;; ) {
            Socket socket = server.accept( );
            System.out.println( "Got local connection on port "
                    + localPort );
            InputStream localIs = socket.getInputStream( );
            OutputStream localOs = socket.getOutputStream( );
            Socket clientSocket = new Socket( remoteHost, remotePort );
            final String description = "Port forwarding: " + localPort
                    + " -> " + remoteHost + ":" + remotePort;
            System.out.println( description + " established." );
            InputStream serverIs = clientSocket.getInputStream( );
            OutputStream serverOs = clientSocket.getOutputStream( );
            Barrier barrier = new Barrier(2);
            final Thread t1 = runForwarder( barrier, "> ", localIs, serverOs );
            final Thread t2 = runForwarder( barrier, "< ", serverIs, localOs );
            waitForConnectionClose( description, t1, t2 );
        }
    }

    /**
     * @param description
     * @param t1
     * @param t2
     */
    private void waitForConnectionClose( final String description,
            final Thread t1, final Thread t2 ) {
        new Thread( new Runnable( ) {
            public void run( ) {
                try {
                    t1.join( );
                    t2.join( );
                } catch ( InterruptedException e ) {
                    e.printStackTrace( );
                }
                System.out.println( description + " closed" );
            }
        } ).start( );
    }

    private Thread runForwarder( final Barrier barrier, final String prefix,
            final InputStream is, final OutputStream os ) {
        Thread t = new ForwarderThread(prefix, barrier, is, os);
        t.start( );
        return t;
    }
}