Add a socks proxy to udp client trackers.

Author: yciabaud

client.js

@@ -32,6 +32,7 @@ inherits(Client, EventEmitter)
  * @param {number} opts.rtcConfig                RTCPeerConnection configuration object
  * @param {number} opts.wrtc                     custom webrtc impl (useful in node.js)
  * @param {object} opts.httpAgent                HTTP agent impl (used to proxy http requests in node.js)
+ * @param {object} opts.socksProxyOpts           socks proxy options (used to proxy UDP requests in node.js)
  */
 function Client (opts) {
   var self = this
@@ -64,6 +65,7 @@ function Client (opts) {
   self._rtcConfig = opts.rtcConfig
   self._wrtc = opts.wrtc
   self._httpAgent = opts.httpAgent
+  self._socksProxyOpts = opts.socksProxyOpts
   self._getAnnounceOpts = opts.getAnnounceOpts
 
   debug('new client %s', self.infoHash)

lib/client/udp-tracker.js

@@ -7,6 +7,7 @@ var debug = require('debug')('bittorrent-tracker:udp-tracker')
 var dgram = require('dgram')
 var inherits = require('inherits')
 var randombytes = require('randombytes')
+var Socks = require('socks')
 var url = require('url')
 
 var common = require('../common')
@@ -63,8 +64,27 @@ UDPTracker.prototype._request = function (opts) {
   var self = this
   if (!opts) opts = {}
   var parsedUrl = url.parse(self.announceUrl)
+  if (!parsedUrl.port) {
+    parsedUrl.port = 80
+  }
+  var timeout
+  var socket
   var transactionId = genTransactionId()
-  var socket = dgram.createSocket('udp4')
+  if (self.client._socksProxyOpts) {
+    // UDP requests uses the associate command
+    self.client._socksProxyOpts.command = 'associate'
+    if (!self.client._socksProxyOpts.target) {
+      // This should contain client IP and port but can be set to 0 if we don't have this information
+      self.client._socksProxyOpts.target = {
+        host: '0.0.0.0',
+        port: 0
+      }
+    }
+
+    Socks.createConnection(self.client._socksProxyOpts, onGotSocket)
+  } else {
+    onGotSocket(null, dgram.createSocket('udp4'))
+  }
 
   var cleanup = function () {
     if (!socket) return
@@ -81,23 +101,29 @@ UDPTracker.prototype._request = function (opts) {
   }
   self.cleanupFns.push(cleanup)
 
-  // does not matter if `stopped` event arrives, so supress errors & cleanup after timeout
-  var ms = opts.event === 'stopped' ? TIMEOUT / 10 : TIMEOUT
-  var timeout = setTimeout(function () {
-    timeout = null
-    if (opts.event === 'stopped') cleanup()
-    else onError(new Error('tracker request timed out (' + opts.event + ')'))
-  }, ms)
-  if (timeout.unref) timeout.unref()
+  function onGotSocket (err, s, info) {
+    if (err) return onError(err)
 
-  send(Buffer.concat([
-    common.CONNECTION_ID,
-    common.toUInt32(common.ACTIONS.CONNECT),
-    transactionId
-  ]))
+    socket = s
 
-  socket.on('error', onError)
-  socket.on('message', onSocketMessage)
+    // does not matter if `stopped` event arrives, so supress errors & cleanup after timeout
+    var ms = opts.event === 'stopped' ? TIMEOUT / 10 : TIMEOUT
+    timeout = setTimeout(function () {
+      timeout = null
+      if (opts.event === 'stopped') cleanup()
+      else onError(new Error('tracker request timed out (' + opts.event + ')'))
+    }, ms)
+    if (timeout.unref) timeout.unref()
+
+    send(Buffer.concat([
+      common.CONNECTION_ID,
+      common.toUInt32(common.ACTIONS.CONNECT),
+      transactionId
+    ]), info)
+
+    socket.on('error', onError)
+    socket.on('message', onSocketMessage)
+  }
 
   function onSocketMessage (msg) {
     if (self.destroyed) return
@@ -180,11 +206,13 @@ UDPTracker.prototype._request = function (opts) {
     self.client.emit('warning', err)
   }
 
-  function send (message) {
-    if (!parsedUrl.port) {
-      parsedUrl.port = 80
+  function send (message, info) {
+    if (info) {
+      var pack = Socks.createUDPFrame({ host: parsedUrl.hostname, port: parsedUrl.port }, message)
+      socket.send(pack, 0, pack.length, info.port, info.host)
+    } else {
+      socket.send(message, 0, message.length, parsedUrl.port, parsedUrl.hostname)
     }
-    socket.send(message, 0, message.length, parsedUrl.port, parsedUrl.hostname)
   }
 
   function announce (connectionId, opts) {

package.json

@@ -14,7 +14,8 @@
     "./lib/common-node.js": false,
     "./lib/client/http-tracker.js": false,
     "./lib/client/udp-tracker.js": false,
-    "./server.js": false
+    "./server.js": false,
+    "socks": false
   },
   "bugs": {
     "url": "https://github.com/feross/bittorrent-tracker/issues"
@@ -38,6 +39,7 @@
     "simple-get": "^2.0.0",
     "simple-peer": "^6.0.0",
     "simple-websocket": "^4.0.0",
+    "socks": "^1.1.9",
     "string2compact": "^1.1.1",
     "uniq": "^1.0.1",
     "ws": "^1.0.0",