Merge pull request #1923 from webtorrent/add_utp_support

uTP support (disabled by default). when enabled, uTP is tried first for all ip:port and timeouts fall back to TCP

Co-authored-by: Pierre Dubouilh <pldubouilh@gmail.com>

1 files changed, 24 insertions, 11 deletions

diff --git a/lib/torrent.js b/lib/torrent.js
index e2ee673..f24ccf3 100644
--- a/lib/torrent.js
+++ b/lib/torrent.js
@@ -24,6 +24,7 @@ const sha1 = require('simple-sha1')
 const speedometer = require('speedometer')
 const utMetadata = require('ut_metadata')
 const utPex = require('ut_pex') // browser exclude
+const utp = require('utp-native') // browser exclude
 const parseRange = require('parse-numeric-range')
 
 const File = require('./file')
@@ -750,7 +751,8 @@ class Torrent extends EventEmitter {
       }
     }
 
-    const wasAdded = !!this._addPeer(peer)
+    // if the utp connection fails to connect, then it is replaced with a tcp connection to the same ip:port
+    const wasAdded = !!this._addPeer(peer, this.client.utp ? 'utp' : 'tcp')
     if (wasAdded) {
       this.emit('peer', peer)
     } else {
@@ -759,7 +761,7 @@ class Torrent extends EventEmitter {
     return wasAdded
   }
 
-  _addPeer (peer) {
+  _addPeer (peer, type) {
     if (this.destroyed) {
       if (typeof peer !== 'string') peer.destroy()
       return null
@@ -787,7 +789,7 @@ class Torrent extends EventEmitter {
     let newPeer
     if (typeof peer === 'string') {
       // `peer` is an addr ("ip:port" string)
-      newPeer = Peer.createTCPOutgoingPeer(peer, this)
+      newPeer = type === 'utp' ? Peer.createUTPOutgoingPeer(peer, this) : Peer.createTCPOutgoingPeer(peer, this)
     } else {
       // `peer` is a WebRTC connection (simple-peer)
       newPeer = Peer.createWebRTCPeer(peer, this)
@@ -1682,7 +1684,7 @@ class Torrent extends EventEmitter {
     const peer = this._queue.shift()
     if (!peer) return // queue could be empty
 
-    this._debug('tcp connect attempt to %s', peer.addr)
+    this._debug('%s connect attempt to %s', peer.type, peer.addr)
 
     const parts = addrToIPPort(peer.addr)
     const opts = {
@@ -1690,7 +1692,13 @@ class Torrent extends EventEmitter {
       port: parts[1]
     }
 
-    const conn = peer.conn = net.connect(opts)
+    if (peer.type === 'utpOutgoing') {
+      peer.conn = utp.connect(opts.port, opts.host)
+    } else {
+      peer.conn = net.connect(opts)
+    }
+
+    const conn = peer.conn
 
     conn.once('connect', () => { peer.onConnect() })
     conn.once('error', err => { peer.destroy(err) })
@@ -1703,11 +1711,16 @@ class Torrent extends EventEmitter {
       // TODO: If torrent is done, do not try to reconnect after a timeout
 
       if (peer.retries >= RECONNECT_WAIT.length) {
-        this._debug(
-          'conn %s closed: will not re-add (max %s attempts)',
-          peer.addr, RECONNECT_WAIT.length
-        )
-        return
+        if (this.client.utp) {
+          const newPeer = this._addPeer(peer.addr, 'tcp')
+          if (newPeer) newPeer.retries = 0
+        } else {
+          this._debug(
+            'conn %s closed: will not re-add (max %s attempts)',
+            peer.addr, RECONNECT_WAIT.length
+          )
+          return
+        }
       }
 
       const ms = RECONNECT_WAIT[peer.retries]
@@ -1717,7 +1730,7 @@ class Torrent extends EventEmitter {
       )
 
       const reconnectTimeout = setTimeout(() => {
-        const newPeer = this._addPeer(peer.addr)
+        const newPeer = this._addPeer(peer.addr, this.client.utp ? 'utp' : 'tcp')
         if (newPeer) newPeer.retries = peer.retries + 1
       }, ms)
       if (reconnectTimeout.unref) reconnectTimeout.unref()