forward.js

var url  = require('url');
var httpProxy = require('http-proxy');

function startForward(proxy_port, proxy_host) {

  var proxy = httpProxy.createServer(function (req, res, proxy) {

    var _url  = url.parse(req.url);

    var dest  = _url.hostname;
    var port  = _url.port || 80;
    var host  = '127.0.0.1';

    var target;
    if(proxy_host === '<ANY>' || proxy_host === dest) {

      target = {
        host: host,
        port: port
      };

      var urlmatch = req.url.match(/http:\/\/[^/]*:?[0-9]*(\/.*)$/);

      if(urlmatch) {
        req.url = urlmatch[1];
      } else {
        req.url = '/';
      }

    } else {
      target = {
        host: dest,
        port: port
      };
    }
    proxy.proxyRequest(req, res, target);

  });

  proxy.listen(proxy_port, function(){
    if(process.getuid() === 0) {
      process.setuid(process.env.SUDO_USER);
    }
  });
}

startForward(process.env.PROXY_PORT, process.env.PROXY_HOST);