Add support for NAT traversal techniques

index.js

@@ -110,6 +110,8 @@ function WebTorrent (opts) {
     }
   }
 
+  self._natTraversal = require('./lib/nat-traversal') // browser exclude
+
   if (typeof TCPPool === 'function') {
     self._tcpPool = new TCPPool(self)
   } else {
@@ -132,7 +134,12 @@ function WebTorrent (opts) {
 
     self.dht.once('listening', function () {
       var address = self.dht.address()
-      if (address) self.dhtPort = address.port
+      if (address) {
+        self.dhtPort = address.port
+        if (self._natTraversal.portMapping) {
+          self._natTraversal.portMapping(self.dhtPort)
+        }
+      }
     })
 
     // Ignore warning when there are > 10 torrents in the client
@@ -431,6 +438,12 @@ WebTorrent.prototype._destroy = function (err, cb) {
     })
   }
 
+  if (self._natTraversal.destroy) {
+    tasks.push(function (cb) {
+      self._natTraversal.destroy(cb)
+    })
+  }
+
   parallel(tasks, cb)
 
   if (err) self.emit('error', err)
@@ -448,7 +461,12 @@ WebTorrent.prototype._onListening = function () {
     // Sometimes server.address() returns `null` in Docker.
     // WebTorrent issue: https://github.com/feross/bittorrent-swarm/pull/18
     var address = this._tcpPool.server.address()
-    if (address) this.torrentPort = address.port
+    if (address) {
+      this.torrentPort = address.port
+      if (this._natTraversal.portMapping) {
+        this._natTraversal.portMapping(this.torrentPort)
+      }
+    }
   }
 
   this.emit('listening')

lib/nat-traversal.js

@@ -0,0 +1,156 @@
+var arrayRemove = require('unordered-array-remove')
+var debug = require('debug')('webtorrent:nat-traversal')
+var natUpnp = require('nat-upnp') // browser exclude
+var natpmp = require('nat-pmp') // browser exclude
+var network = require('network') // browser exclude
+
+// Use single instance
+module.exports = new NatTraversal()
+
+function NatTraversal () {
+  var self = this
+  self._destroyed = false
+
+  // The RECOMMENDED Port Mapping Lifetime is 7200 seconds (two hours).
+  self.ttl = 7200
+  // Refresh the mapping 10 minutes before the end of its lifetime
+  self.timeout = (self.ttl - 600) * 1000
+  self._openedPorts = []
+  self._intervalsUpnp = {}
+  self._intervalsPmp = {}
+
+  self._upnpPortMapping = function (port, cb) {
+    var self = this
+
+    debug('Mapping port %d on router using UPnP', port)
+    self._upnpClient.portMapping({
+      public: port,
+      private: port,
+      description: 'WebTorrent',
+      ttl: self.ttl
+    }, function (err) {
+      if (self._destroyed) return typeof cb === 'function' && cb()
+      if (err) {
+        return typeof cb === 'function' && cb(err)
+      }
+      self._intervalsUpnp[port] = setInterval(self._pmpPortMapping.bind(self, port), self.timeout)
+      debug('Port %d mapped on router using UPnP', port)
+      if (typeof cb === 'function') cb()
+    })
+  }
+
+  self._pmpPortMapping = function (port, cb) {
+    var self = this
+
+    debug('Mapping port %d on router using NAT-PMP', port)
+    self._pmpClient.portMapping({
+      private: port,
+      public: port,
+      ttl: self.ttl,
+      type: 'tcp'
+    }, function (err/* , info */) {
+      if (self._destroyed) return typeof cb === 'function' && cb()
+      if (err) {
+        debug('Error mapping port %d using NAT-PMP', port, err)
+        return typeof cb === 'function' && cb(err)
+      }
+      self._intervalsPmp[port] = setInterval(self._pmpPortMapping.bind(self, port), self.timeout)
+      debug('Port %d mapped on router using NAT-PMP', port)
+      if (typeof cb === 'function') cb()
+    })
+  }
+
+  debug('UPnP client creation')
+  self._upnpClient = natUpnp.createClient()
+
+  // Lookup gateway IP
+  debug('Lookup gateway IP')
+  network.get_gateway_ip(function (err, ip) {
+    if (self._destroyed) return
+    if (err) {
+      return debug('Could not find gateway IP for NAT-PMP', err)
+    }
+    debug('NAT-PMP client creation', ip)
+    self._pmpClient = natpmp.connect(ip)
+    self._openedPorts.forEach(function (port) {
+      self._pmpPortMapping(port)
+    })
+  })
+}
+
+NatTraversal.prototype.portMapping = function (port, cb) {
+  var self = this
+  if (self._destroyed) return typeof cd === 'function' && cb()
+
+  self._openedPorts.push(port)
+
+  // Try UPnP first
+  self._upnpPortMapping(port, function (err) {
+    if (self._destroyed) return typeof cb === 'function' && cb()
+    if (err) {
+      debug('UPnP port mapping failed on %d', port, err.message)
+    }
+
+    // Then NAT-PMP
+    if (self._pmpClient) {
+      self._pmpPortMapping(port, cb)
+    } else if (typeof cb === 'function') {
+      cb()
+    }
+  })
+}
+
+NatTraversal.prototype.portUnMapping = function (port, cb) {
+  var self = this
+  if (self._destroyed) return typeof cd === 'function' && cb()
+  arrayRemove(self._openedPorts, self._openedPorts.indexOf(port))
+
+  // Clear intervals
+  if (self._intervalsUpnp[port]) {
+    clearInterval(self._intervalsUpnp[port])
+    delete self._intervalsUpnp[port]
+  }
+  if (self._intervalsPmp[port]) {
+    clearInterval(self._intervalsPmp[port])
+    delete self._intervalsPmp[port]
+  }
+
+  debug('Unmapping port %d on router using UPnP', port)
+  self._upnpClient.portUnmapping({
+    public: port
+  }, function (err) {
+    if (!err) debug('Port %d unmapped on router using UPnP', port)
+    if (self._pmpClient) {
+      debug('Unmapping port %d on router using NAT-PMP', port)
+      self._pmpClient.portUnmapping({
+        private: port,
+        public: port
+      }, cb)
+    } else {
+      if (typeof cb === 'function') cb()
+    }
+  })
+}
+
+NatTraversal.prototype.destroy = function (cb) {
+  var self = this
+  if (self._destroyed) return cb()
+
+  // Unmap all ports
+  self._openedPorts.forEach(function (port) {
+    self.portUnMapping(port)
+  })
+  self._destroyed = true
+
+  if (self._pmpClient) {
+    debug('Close pmp client')
+    self._pmpClient.close()
+  }
+
+  // Waiting next tick to prevent breaking some sockets
+  process.nextTick(function () {
+    debug('Close UPnP client')
+    self._upnpClient.close()
+    cb()
+  })
+}

lib/server.js

@@ -9,13 +9,15 @@ var url = require('url')
 
 function Server (torrent, opts) {
   var server = http.createServer(opts)
+  var natTraversal = require('./nat-traversal')
 
   var sockets = []
   var pendingReady = []
   var closed = false
 
   server.on('connection', onConnection)
   server.on('request', onRequest)
+  server.on('listening', onListening)
 
   var _close = server.close
   server.close = function (cb) {
@@ -35,6 +37,10 @@ function Server (torrent, opts) {
       socket.destroy()
     })
 
+    if (server.address()) {
+      natTraversal.portUnMapping(server.address().port)
+    }
+
     // Only call `server.close` if user has not called it already
     if (!cb) cb = function () {}
     if (closed) process.nextTick(cb)
@@ -195,6 +201,10 @@ function Server (torrent, opts) {
     }
   }
 
+  function onListening () {
+    natTraversal.portMapping(server.address().port)
+  }
+
   return server
 }
 

package.json

@@ -8,12 +8,16 @@
     "url": "https://webtorrent.io"
   },
   "browser": {
+    "./lib/nat-traversal.js": false,
     "./lib/server.js": false,
     "./lib/tcp-pool.js": false,
     "bittorrent-dht/client": false,
     "fs-chunk-store": "memory-chunk-store",
     "load-ip-set": false,
+    "nat-pmp": false,
+    "nat-upnp": false,
     "net": false,
+    "network": false,
     "os": false,
     "ut_pex": false
   },
@@ -41,6 +45,9 @@
     "memory-chunk-store": "^1.2.0",
     "mime": "^1.3.4",
     "multistream": "^2.0.5",
+    "nat-pmp": "github:yciabaud/node-nat-pmp#patch-1",
+    "nat-upnp": "^1.0.4",
+    "network": "^0.3.2",
     "package-json-versionify": "^1.0.2",
     "parse-torrent": "^5.8.0",
     "pump": "^1.0.1",