Socks library snippet for Node.js

socks.js

var net = require('net'),
    util = require('util'),
    EventEmitter = require('events').EventEmitter;

var SOCKSClient = module.exports = function() {
    var args = normalizeConnectArgs(arguments);
    this.state = 'connecting';
    this.socket = net.connect(args[0].port, args[0].host, onConnect.bind(this));
    this.socket.on('data', onData.bind(this));
    this.socket.on('end', onEnd.bind(this));
    args[1] && this.on('connect', args[1]);
    return this;
};
util.inherits(SOCKSClient, EventEmitter);
SOCKSClient.prototype.connect = SOCKSClient.prototype.createConnection = function() {
    if (this.state != "authenticated") return;
    var args = normalizeConnectArgs(arguments);
    this.virtualSocket = new SOCKSSocket(this, args[0].host, args[0].port, args[1]);
    return this.virtualSocket;
}

var SOCKSSocket = function(client, host, port, cb) {
    this.host = host;
    this.port = port;
    this.client = client;
    
    cb && this.on('connect', cb);

    var portBuf = new Buffer(2);
    portBuf.writeUInt16BE(port, 0);
    var lenBuf = new Buffer(1);
    lenBuf.writeUInt8(Buffer.byteLength(host), 0);
    this.client.socket.write("\x05\x01\x00\x03" + lenBuf.toString() + host + portBuf.toString());
    this.client.state = "connectrequest";
}
util.inherits(SOCKSSocket, EventEmitter);
SOCKSSocket.prototype.setEncoding = function(enc) { this.encoding = enc; }
SOCKSSocket.prototype.write = function(data) { this.client.socket.write(data); };
SOCKSSocket.prototype.end = function() { this.client.socket.end(); };

var normalizeConnectArgs = function(args) {
    var options = {};

    if (typeof args[0] === 'object') {
        // connect(options, [cb])
        options = args[0];
    } else {
        // connect(port, [host], [cb])
        options.port = args[0];
        if (typeof args[1] === 'string') {
            options.host = args[1];
        }
    }

    var cb = args[args.length - 1];
    return (typeof cb === 'function') ? [options, cb] : [options];
};
var onConnect = function() {
    this.socket.write("\x05\x01\x00"); // We only support the "no authentication" (0x00) scheme
    this.state = "connected";
};
var onData = function(data) {
    switch (this.state) {
        case "connected":
            if (data[0] == 0xff) {
                console.error("socks: no acceptable authentication methods were offered");
                this.socket.end();
                this.state = "failed";
                return;
            } 
            this.state = "authenticated";
            this.emit("connect");
            break;
        case "connectrequest":
            if (data[1] != 0x00) {
                console.error("socks: connect request failed: error code " + data[1]);
                this.socket.end();
                this.state = "failed";
                return;
            }
            this.virtualSocket.emit("connect");
            this.state = "socketconnected";
            break;
        case "socketconnected":
            if (this.virtualSocket.encoding) data = data.toString(this.virtualSocket.encoding);
            this.virtualSocket.emit("data", data);
            break;
        case "authenticated":
        default:
            console.log(this.state, data);
    }
};
var onEnd = function() {
    this.virtualSocket && this.virtualSocket.emit('end');
    this.emit('end');
};

//test 
/*
var socks = new SOCKSClient(9050, function() {
    console.log('connected to socks');
    var socket = socks.connect(80, 'www.google.com', function() {
        console.log('connected to host');
        socket.write("GET / HTTP/1.0\r\n\r\n");
        socket.setEncoding('utf8');
        socket.on('data', function(data) {
            console.log(data);
        });
    });
}); //*/