RelayProxy.js implements a forward proxy server in node.js with support for:

• HTTP and HTTPS requests (SOCKS5 support coming in a future version)
• Basic HTTP authorization
• Forwarding to a remote proxy (with support for remote authorization), selectable at run-time based on incoming header and credentials

I wrote this server as I had a need for a private authenticated proxy server that would forward the request through a remote private proxy. The idea was to manage the amount of access a connecting client had to any given address and to manage which remote proxies (taken from a pool of rented third-party private proxies, each requiring authorization) were allocated to a given client, rotating those proxies depending on usage.

The server is very simple to use:

Usage

Basic usage

At its simplest, the following will instantiate a non-authenticating transparent proxy that forwards requests to the target url without relaying the request through a third-party proxy:

var RelayProxy = require('./path/to/relay-proxy');
var server = new RelayProxy();
server.listen(3333);

Local authorization

To authorize access to your proxy, provide a handler function:

var RelayProxy = require('./path/to/relay-proxy');
var server = new RelayProxy();

server.authorize(function(req, username, password, callback) {
    // replace with code to verify username and password
    var isLoginCorrect = true;
    
    // call the supplied callback function to continue the request
    callback(null, isLoginCorrect);
});

server.listen(3333);

Using a remote proxy

To forward requests via a third-party proxy, provide a handler function:

var RelayProxy = require('./path/to/relay-proxy');
var server = new RelayProxy();

server.selectForwardProxy(function(req, username, callback) {
    
    var proxy = {
        host: '1.2.3.4',
        port: 31337,
        username: 'jimbob', // only supply a username and password if
        password: 'mcgee'   // the remote proxy requires authorization
    };
    
    // the callback's second argument can be one of three values:
    // null:  no remote proxy - forward directly to the requested url
    // false: decline to forward the request (http 407 sent back to client)
    // proxy: proxy options as specified in the above sample

    callback(null, proxy);
});

server.listen(3333);

Dependencies

RelayProxy has a dependency on node-http-proxy, by the good folks at Nodejitsu. Thankfully, it's available in the npm registry.