Respect the "private" flag in .torrent files

lib/torrent.js

@@ -196,7 +196,9 @@ Torrent.prototype._onParsedTorrent = function (parsedTorrent) {
 
   // create swarm
   self.swarm = new Swarm(self.infoHash, self.client.peerId, {
-    handshake: { dht: !!self.client.dht }
+    handshake: {
+      dht: self.private ? false : !!self.client.dht
+    }
   })
   self.swarm.on('error', self._onError.bind(self))
   self.swarm.on('wire', self._onWire.bind(self))
@@ -263,7 +265,9 @@ Torrent.prototype._onSwarmListening = function () {
   // begin discovering peers via the DHT and tracker servers
   self.discovery = new Discovery({
     announce: self.announce,
-    dht: self.client.dht,
+    dht: self.private
+      ? false
+      : self.client.dht,
     tracker: self.client.tracker,
     peerId: self.client.peerId,
     port: self.client.torrentPort,
@@ -587,8 +591,8 @@ Torrent.prototype._onWire = function (wire, addr) {
     wire.ut_metadata.fetch()
   }
 
-  // use ut_pex extension
-  if (typeof ut_pex === 'function') {
+  // use ut_pex extension if the torrent is not flagged as private
+  if (typeof ut_pex === 'function' && !self.private) {
     wire.use(ut_pex())
 
     // wire.ut_pex.start() // TODO two-way communication

test/download-private-dht.js

@@ -0,0 +1,118 @@
+var auto = require('run-auto')
+var DHT = require('bittorrent-dht/server')
+var fs = require('fs')
+var parseTorrent = require('parse-torrent')
+var test = require('tape')
+var WebTorrent = require('../')
+
+var bunnyTorrent = fs.readFileSync(__dirname + '/torrents/big-buck-bunny-private.torrent')
+var bunnyParsed = parseTorrent(bunnyTorrent)
+
+var leavesTorrent = fs.readFileSync(__dirname + '/torrents/leaves.torrent')
+var leavesParsed = parseTorrent(leavesTorrent)
+
+// remove trackers from .torrent file
+bunnyParsed.announce = []
+leavesParsed.announce = []
+
+test('private torrent should not use DHT', function (t) {
+  t.plan(3)
+
+  var dhtServer = new DHT({ bootstrap: false })
+
+  dhtServer.on('error', function (err) { t.fail(err) })
+  dhtServer.on('warning', function (err) { t.fail(err) })
+
+  auto({
+    dhtPort: function (cb) {
+      dhtServer.listen(function () {
+        var port = dhtServer.address().port
+        cb(null, port)
+      })
+    },
+
+    client: ['dhtPort', function (cb, r) {
+      var client = new WebTorrent({
+        tracker: false,
+        dht: { bootstrap: '127.0.0.1:' + r.dhtPort }
+      })
+      client.on('error', function (err) { t.fail(err) })
+      client.on('warning', function (err) { t.fail(err) })
+
+      var torrent = client.add(bunnyParsed)
+
+      torrent.on('dhtAnnounce', function () {
+        t.fail('client announced to dht')
+      })
+
+      client.on('torrent', function () {
+        if (!torrent.discovery.dht && !torrent.swarm.handshakeOpts.dht) {
+          t.pass('dht is disabled for this torrent')
+          cb(null, client)
+        }
+      })
+
+    }]
+
+  }, function (err, r) {
+    if (err) throw err
+
+    dhtServer.destroy(function () {
+      t.pass('dht server destroyed')
+    })
+    r.client.destroy(function () {
+      t.pass('client destroyed')
+    })
+  })
+})
+
+test('public torrent should use DHT', function (t) {
+  t.plan(3)
+
+  var dhtServer = new DHT({ bootstrap: false })
+
+  dhtServer.on('error', function (err) { t.fail(err) })
+  dhtServer.on('warning', function (err) { t.fail(err) })
+
+  auto({
+    dhtPort: function (cb) {
+      dhtServer.listen(function () {
+        var port = dhtServer.address().port
+        cb(null, port)
+      })
+    },
+
+    client: ['dhtPort', function (cb, r) {
+      var client = new WebTorrent({
+        tracker: false,
+        dht: { bootstrap: '127.0.0.1:' + r.dhtPort }
+      })
+      client.on('error', function (err) { t.fail(err) })
+      client.on('warning', function (err) { t.fail(err) })
+
+      var torrent = client.add(leavesParsed)
+
+      torrent.on('dhtAnnounce', function () {
+        t.pass('client announced to dht')
+        cb(null, client)
+      })
+
+      client.on('torrent', function () {
+        if (!torrent.client.dht) {
+          t.fail('dht server is null')
+        }
+      })
+
+    }]
+
+  }, function (err, r) {
+    if (err) throw err
+
+    dhtServer.destroy(function () {
+      t.pass('dht server destroyed')
+    })
+    r.client.destroy(function () {
+      t.pass('client destroyed')
+    })
+  })
+})