Add Local Service Discovery (BEP14)

README.md

@@ -11,14 +11,13 @@
 
 ### Discover BitTorrent and WebTorrent peers
 
-This module bundles [bittorrent-dht](https://www.npmjs.com/package/bittorrent-dht) and
-[bittorrent-tracker](https://www.npmjs.com/package/bittorrent-tracker) clients and exposes a
-single API for discovering BitTorrent peers via both discovery methods.
+This module bundles [bittorrent-dht](https://www.npmjs.com/package/bittorrent-dht),
+[bittorrent-tracker](https://www.npmjs.com/package/bittorrent-tracker) and [bittorrent-lsd](https://www.npmjs.com/package/bittorrent-lsd) clients and exposes a single API for discovering BitTorrent peers via both discovery methods.
 
 ## features
 
 - simple API
-- find peers from trackers and the DHT
+- find peers from trackers, DHT and LSD
 - automatically announces, so other peers can discover us
 - can start finding peers with just an info hash, before full metadata is available
 
@@ -54,12 +53,12 @@ Optional options are:
   dhtPort: 0,    // custom listen port for the DHT instance (not used if DHT instance is given via `opts.dht`)
   userAgent: '', // User-Agent header for http requests
   tracker: true, // use trackers? optionally, this can be an `opts` object
+  lsd: true      // use lsd?
 }
 ```
 
-See the documentation for [bittorrent-dht](https://www.npmjs.com/package/bittorrent-dht) and
-[bittorrent-tracker](https://www.npmjs.com/package/bittorrent-tracker) for information on what
-options are available via the `opts` object.
+See the documentation for [bittorrent-dht](https://www.npmjs.com/package/bittorrent-dht),
+[bittorrent-tracker](https://www.npmjs.com/package/bittorrent-tracker) and [bittorrant-lsd](https://www.npmjs.com/package/bittorrent-lsd) for information on what options are available via the `opts` object.
 
 **This module automatically handles announcing on intervals, for maximum peer discovery.**
 
@@ -85,13 +84,13 @@ Optional `opts` object with the following options:
 
 ### `discovery.destroy()`
 
-Destroy and cleanup the DHT and tracker instances.
+Destroy and cleanup the DHT, tracker and LSD instances.
 
 ### events
 
 ### `discovery.on('peer', (peer, source) => {})`
 
-Emitted whenever a new peer is discovered. Source is either 'tracker' or 'dht' based on peer source.
+Emitted whenever a new peer is discovered. Source is either 'tracker', 'dht' or 'lsd' based on peer source.
 
 **In node**, `peer` is a string in the form `ip:port`, e.g. `12.34.56.78:4000`.
 
@@ -105,12 +104,12 @@ Emitted whenever an `announce` message has been sent to the DHT.
 
 ### `discovery.on('warning', err => {})`
 
-Emitted when there is a non-fatal DHT or tracker error, like an inaccessible tracker
+Emitted when there is a non-fatal DHT, tracker or LSD error, like an inaccessible tracker
 server. Useful for logging. This is non-fatal.
 
 ### `discovery.on('error', err => {})`
 
-Emitted when there is a fatal, unrecoverable DHT or tracker error.
+Emitted when there is a fatal, unrecoverable DHT, tracker or LSD error.
 
 ## license
 

index.js

@@ -4,6 +4,7 @@ const DHT = require('bittorrent-dht/client') // empty object in browser
 const EventEmitter = require('events').EventEmitter
 const parallel = require('run-parallel')
 const Tracker = require('bittorrent-tracker/client')
+const LSD = require('bittorrent-lsd')
 
 class Discovery extends EventEmitter {
   constructor (opts) {
@@ -47,6 +48,9 @@ class Discovery extends EventEmitter {
     this._onTrackerAnnounce = () => {
       this.emit('trackerAnnounce')
     }
+    this._onLSDPeer = (peer, infoHash) => {
+      this.emit('peer', peer, 'lsd')
+    }
 
     const createDHT = (port, opts) => {
       const dht = new DHT(opts)
@@ -80,6 +84,12 @@ class Discovery extends EventEmitter {
       this.dht.on('peer', this._onDHTPeer)
       this._dhtAnnounce()
     }
+
+    if (opts.lsd === false) {
+      this.lsd = null
+    } else {
+      this.lsd = this._createLSD()
+    }
   }
 
   updatePort (port) {
@@ -133,11 +143,21 @@ class Discovery extends EventEmitter {
       })
     }
 
+    if (this.lsd) {
+      this.lsd.removeListener('warning', this._onWarning)
+      this.lsd.removeListener('error', this._onError)
+      this.lsd.removeListener('peer', this._onLSDPeer)
+      tasks.push(cb => {
+        this.lsd.destroy(cb)
+      })
+    }
+
     parallel(tasks, cb)
 
     // cleanup
     this.dht = null
     this.tracker = null
+    this.lsd = null
     this._announce = null
   }
 
@@ -182,6 +202,21 @@ class Discovery extends EventEmitter {
       }
     })
   }
+
+  _createLSD () {
+    const opts = Object.assign({}, {
+      infoHash: this.infoHash,
+      peerId: this.peerId,
+      port: this._port
+    })
+
+    const lsd = new LSD(opts)
+    lsd.on('warning', this._onWarning)
+    lsd.on('error', this._onError)
+    lsd.on('peer', this._onLSDPeer)
+    lsd.start()
+    return lsd
+  }
 }
 
 module.exports = Discovery

package.json

@@ -8,7 +8,8 @@
     "url": "https://webtorrent.io"
   },
   "browser": {
-    "bittorrent-dht/client": false
+    "bittorrent-dht/client": false,
+    "bittorrent-lsd": false
   },
   "chromeapp": {},
   "bugs": {
@@ -17,6 +18,7 @@
   "dependencies": {
     "bittorrent-dht": "^10.0.0",
     "bittorrent-tracker": "^9.0.0",
+    "bittorrent-lsd": "^1.0.0",
     "debug": "^4.0.0",
     "run-parallel": "^1.1.2"
   },
@@ -33,6 +35,7 @@
     "discovery",
     "tracker",
     "dht",
+    "lsd",
     "trackers",
     "find peers",
     "peer-to-peer",

test/basic.js

@@ -19,13 +19,15 @@ test('initialize with dht', t => {
   })
 })
 
-test('initialize with default dht', t => {
-  t.plan(1)
+test('initialize with default dht and lsd', t => {
+  t.plan(3)
   const discovery = new Discovery({
     infoHash: randombytes(20),
     peerId: randombytes(20),
     port: 6000
   })
+  t.ok(discovery.dht)
+  t.ok(discovery.lsd)
   discovery.destroy(() => {
     t.pass()
   })
@@ -44,3 +46,17 @@ test('initialize without dht', t => {
     t.pass()
   })
 })
+
+test('initialize without lsd', t => {
+  t.plan(2)
+  const discovery = new Discovery({
+    infoHash: randombytes(20),
+    peerId: randombytes(20),
+    port: 6000,
+    lsd: false
+  })
+  t.equal(discovery.lsd, null)
+  discovery.destroy(() => {
+    t.pass()
+  })
+})