proxy.js

var http = require('http'),
    sys  = require('sys');

exports.createServer = function createServer (port, host) {
  return new HttpProxy({
    port: +port,
    host: host || '0.0.0.0'
  });
};

var ClientPool = function ClientPool (port, host) {
  this.port    = +port;
  this.host    = host;
  this.clients = [];

  return this;
};

ClientPool.prototype.request = function allocRequest (method, path, headers) {
  var client, request, $ = this;

  if (!(client = this.clients.pop())) {
    client = http.createClient(this.port, this.host);
    request = client.request(method, path, headers);
    request.connection.on('close', function () {
      request
      $.clients.push(client);
    });
  } else {
    request = client.request(method, path, headers);
  }

  return request;
};

var HttpProxy = exports.HttpProxy = function HttpProxy (options) {
  this.client_pool = new ClientPool(options.port, options.host);
  http.Server.call(this);

  this.on('request', this.onRequest);
  return this;
};

HttpProxy.prototype = Object.create(http.Server.prototype);

HttpProxy.prototype.onRequest = function onRequest (e_request, e_response) {
  var i_request = this.client_pool.request(e_request.method,
                    e_request.url, e_request.rawHeaders);

  i_request.connection.on('error', function (error) {
    error = 'An error occurred: ' + sys.inspect(error);

    e_response.writeHead(200, {
      'Content-Type':   'text/plain',
      'Content-Length': error.length
    });
    if (e_request.method === 'HEAD') error = null;

    e_response.end(error);
  });

  i_request.on('response', function (i_response) {
    // Pump response
    e_response.writeHead(i_response.statusCode, i_response.rawHeaders);

    sys.pump(i_response, e_response);
    i_response.on('end', function () {
      e_response.end();
    });
  });

  sys.pump(e_request, i_request);
  e_request.on('end', function () {
    i_request.end();
  });
};