relayc.js

var argv = require("optimist")
  .usage('Usage: $0 --sh [host] --sp [port] --rh [host] --rp [port]')
  .demand(['sh', 'sp', 'rh', 'rp'])
  .argv;

console.log(argv);

var net = require("net");

function connect() {
  var relaySocket = new net.Socket();
  var serverSocket = undefined;

  relaySocket.connect(argv.rp, argv.rh, function () {
    console.log("relay socket established");

    relaySocket.on("data", function (data) {
      if (serverSocket == undefined) {
        serverSocket = new net.Socket();
    
        serverSocket.connect(argv.sp, argv.sh, function () {
          console.log("server socket established");
          serverSocket.write(data);
        });
        serverSocket.on("data", function (data) {
          try {
            relaySocket.write(data);
          } catch (ex) {
            console.log(ex);
          }
        });
        serverSocket.on("close", function (had_error) {
          console.log("server socket closed");
          relaySocket.end();
        });
        serverSocket.on("error", function (exception) {
          console.log("server socket error");
          console.log(exception);
          relaySocket.end();
        });
        
        connect();
        console.log("next relay connection established");
      } else {
        try {
          serverSocket.write(data);
        } catch (ex) {
          console.log(ex);
        }        
      }
    });
    relaySocket.on("close", function (had_error) {
      console.log("relay socket closed");
      if (serverSocket != undefined)
        serverSocket.end();
    });
    relaySocket.on("error", function (exception) {
      console.log("relay socket error");
      console.log(exception);
    });
  });
}

connect();