udpproxy in node.js

gistfile1.txt

/*jslint node: true, indent: 2 */

"use strict";

var httpPort = 4022;

var http = require('http');
var dgram = require('dgram');
var querystring = require('querystring');

var udpSockets = {};

http.createServer(function (request, response) {
  var ipAddress = request.socket.remoteAddress,
    socket,
    m;

  request.socket.setTimeout(0);
  console.log("New HTTP connection from: " + ipAddress);

  // request.url should be "/udp/239.255.0.0:1234/", 224-239.0-255.0-255.0-255, port 0 - 65535
  m = request.url.match(/^\/udp\/((?:22[4-9]|23[0-9])(?:\.(?:[0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])){3})\:(\d+)/);
  if (!m) {
    response.writeHead(400);
    response.end();
  }

  response.writeHead(200);
  m = {
    port: Math.min(65535, +m[2]),
    address: m[1]
  };

  function onSocketMessage(message) {
    response.write(message);
  }

  socket = udpSockets[m.address + ':' + m.port];
  if (!socket) {
    socket = dgram.createSocket('udp4');
    socket.bind(m.port, m.address);
    udpSockets[m.address + ':' + m.port] = socket;
    socket.setMaxListeners(0);
  }
  socket.on('message', onSocketMessage);

  request.on('close', function () {
    socket.removeListener('message', onSocketMessage);
    if (!socket.listeners('message').length) {
      socket.close();
      delete udpSockets[m.address + ':' + m.port];
    }
    console.log("Closed HTTP connection: " + ipAddress);
    response.end();
  });
}).listen(httpPort);