listen() without port picks random port

package.json

@@ -25,12 +25,12 @@
     "inherits": "^2.0.1",
     "ip": "^0.3.0",
     "once": "^1.3.0",
+    "portfinder": "^0.2.1",
     "string2compact": "^1.1.1"
   },
   "devDependencies": {
     "magnet-uri": "^2.0.1",
     "parse-torrent": "^1.1.0",
-    "portfinder": "^0.2.1",
     "tape": "^2.13.3"
   },
   "homepage": "http://webtorrent.io",

server.js

@@ -9,8 +9,12 @@ var EventEmitter = require('events').EventEmitter
 var http = require('http')
 var inherits = require('inherits')
 var ipLib = require('ip')
+var portfinder = require('portfinder')
 var string2compact = require('string2compact')
 
+// Use random port above 1024
+portfinder.basePort = Math.floor(Math.random() * 60000) + 1025
+
 var NUM_ANNOUNCE_PEERS = 50
 var MAX_ANNOUNCE_PEERS = 82
 var REMOVE_IPV6_RE = /^::ffff:/
@@ -43,6 +47,7 @@ function Server (opts) {
 
   self._trustProxy = !!opts.trustProxy
 
+  self.listening = false
   self.port = null
   self.torrents = {}
 
@@ -65,7 +70,10 @@ function Server (opts) {
   var num = !!self._httpServer + !!self._udpServer
   function onListening () {
     num -= 1
-    if (num === 0) self.emit('listening', self.port)
+    if (num === 0) {
+      self.listening = true
+      self.emit('listening', self.port)
+    }
   }
 }
 
@@ -76,10 +84,22 @@ Server.prototype._onError = function (err) {
 
 Server.prototype.listen = function (port, onlistening) {
   var self = this
-  self.port = port
+  if (typeof port === 'function') {
+    onlistening = port
+    port = undefined
+  }
+  if (self.listening) throw new Error('server already listening')
   if (onlistening) self.once('listening', onlistening)
+
+  function onPort (err, port) {
+    if (err) return self.emit('error', err)
+    self.port = port
     self._httpServer && self._httpServer.listen(port.http || port)
     self._udpServer && self._udpServer.bind(port.udp || port)
+  }
+
+  if (port) onPort(null, port)
+  else portfinder.getPort(onPort)
 }
 
 Server.prototype.close = function (cb) {

test/server.js

@@ -1,5 +1,4 @@
 var Client = require('../')
-var portfinder = require('portfinder')
 var Server = require('../').Server
 var test = require('tape')
 
@@ -9,7 +8,7 @@ var peerId2 = '12345678901234567890'
 var torrentLength = 50000
 
 function serverTest (t, serverType) {
-  t.plan(27)
+  t.plan(26)
 
   var opts = serverType === 'http' ? { udp: false } : { http: false }
   var server = new Server(opts)
@@ -26,10 +25,7 @@ function serverTest (t, serverType) {
     t.pass('server listening')
   })
 
-  portfinder.getPort(function (err, port) {
-    t.error(err, 'found free port')
-    server.listen(port)
-
+  server.listen(function (port) {
     var announceUrl = 'http://127.0.0.1:' + port + '/announce'
 
     var client = new Client(peerId, 6881, {