index.js

/**
 * Module dependencies.
 */

var tls; // lazy-loaded...
var url = require('url');
var dns = require('dns');
var Agent = require('agent-base');
var SocksClient = require('socks').SocksClient;
var inherits = require('util').inherits;

/**
 * Module exports.
 */

module.exports = SocksProxyAgent;

/**
 * The `SocksProxyAgent`.
 *
 * @api public
 */

function SocksProxyAgent(opts) {
	if (!(this instanceof SocksProxyAgent)) return new SocksProxyAgent(opts);
	if ('string' == typeof opts) opts = url.parse(opts);
	if (!opts)
		throw new Error(
			'a SOCKS proxy server `host` and `port` must be specified!'
		);
	Agent.call(this, opts);

	var proxy = Object.assign({}, opts);

	// prefer `hostname` over `host`, because of `url.parse()`
	proxy.host = proxy.hostname || proxy.host;

	// SOCKS doesn't *technically* have a default port, but this is
	// the same default that `curl(1)` uses
	proxy.port = +proxy.port || 1080;

	if (proxy.host && proxy.path) {
		// if both a `host` and `path` are specified then it's most likely the
		// result of a `url.parse()` call... we need to remove the `path` portion so
		// that `net.connect()` doesn't attempt to open that as a unix socket file.
		delete proxy.path;
		delete proxy.pathname;
	}

	// figure out if we want socks v4 or v5, based on the "protocol" used.
	// Defaults to 5.
	proxy.lookup = false;
	switch (proxy.protocol) {
		case 'socks4:':
			proxy.lookup = true;
		// pass through
		case 'socks4a:':
			proxy.version = 4;
			break;
		case 'socks5:':
			proxy.lookup = true;
		// pass through
		case 'socks:': // no version specified, default to 5h
		case 'socks5h:':
			proxy.version = 5;
			break;
		default:
			throw new TypeError(
				'A "socks" protocol must be specified! Got: ' + proxy.protocol
			);
	}

	if (proxy.auth) {
		var auth = proxy.auth.split(':');
		proxy.authentication = { username: auth[0], password: auth[1] };
		proxy.userid = auth[0];
	}
	this.proxy = proxy;
}
inherits(SocksProxyAgent, Agent);

/**
 * Initiates a SOCKS connection to the specified SOCKS proxy server,
 * which in turn connects to the specified remote host and port.
 *
 * @api public
 */

SocksProxyAgent.prototype.callback = function connect(req, opts, fn) {
	var proxy = this.proxy;

	// called once the SOCKS proxy has connected to the specified remote endpoint
	function onhostconnect(err, result) {
		if (err) return fn(err);

		var socket = result.socket;

		var s = socket;
		if (opts.secureEndpoint) {
			// since the proxy is connecting to an SSL server, we have
			// to upgrade this socket connection to an SSL connection
			if (!tls) tls = require('tls');
			opts.socket = socket;
			opts.servername = opts.servername || opts.host;
			opts.host = null;
			opts.hostname = null;
			opts.port = null;
			s = tls.connect(opts);
		}

		fn(null, s);
	}

	// called for the `dns.lookup()` callback
	function onlookup(err, ip) {
		if (err) return fn(err);
		options.destination.host = ip;
		SocksClient.createConnection(options, onhostconnect);
	}

	var options = {
		proxy: {
			ipaddress: proxy.host,
			port: +proxy.port,
			type: proxy.version
		},
		destination: {
			port: +opts.port
		},
		command: 'connect'
	};

	if (proxy.authentication) {
		options.proxy.userId = proxy.userid;
		options.proxy.password = proxy.authentication.password;
	}

	if (proxy.lookup) {
		// client-side DNS resolution for "4" and "5" socks proxy versions
		dns.lookup(opts.host, onlookup);
	} else {
		// proxy hostname DNS resolution for "4a" and "5h" socks proxy servers
		onlookup(null, opts.host);
	}
};