proxy.js

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

function log(options) {
  var info = [options.method, options.path].join(' ');
  sys.log(info);
}

function proxy(options, req, res) {
  return http.request(options, function(proxy_res) {
    res.writeHead(proxy_res.statusCode, proxy_res.headers);
    proxy_res.pipe(res);
  });
}

function handler(req, res) {
  var options = {
    port: 80,
    path: req.url,
    method: req.method,
    hostname: req.headers.host
  };

  log(options);
  var proxied = proxy(options, req, res);
  req.pipe(proxied);
}

http.createServer(handler).listen(4000);