Implement IPv6 multicast again (fixes #346)

auto/gui.files.go

@@ -73,7 +73,7 @@ func init() {
 	bs, _ = ioutil.ReadAll(gr)
 	Assets["favicon.png"] = bs
 
-	bs, _ = hex.DecodeString("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 truncated
+	bs, _ = hex.DecodeString("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 truncated
 	gr, _ = gzip.NewReader(bytes.NewBuffer(bs))
 	bs, _ = ioutil.ReadAll(gr)
 	Assets["index.html"] = bs

beacon/beacon.go

@@ -0,0 +1,46 @@
+// Copyright (C) 2014 Jakob Borg and Contributors (see the CONTRIBUTORS file).
+// All rights reserved. Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+package beacon
+
+import "net"
+
+type recv struct {
+	data []byte
+	src  net.Addr
+}
+
+type dst struct {
+	intf string
+	conn *net.UDPConn
+}
+
+type Interface interface {
+	Send(data []byte)
+	Recv() ([]byte, net.Addr)
+}
+
+func genericReader(conn *net.UDPConn, outbox chan<- recv) {
+	bs := make([]byte, 65536)
+	for {
+		n, addr, err := conn.ReadFrom(bs)
+		if err != nil {
+			l.Warnln("multicast read:", err)
+			return
+		}
+		if debug {
+			l.Debugf("recv %d bytes from %s", n, addr)
+		}
+
+		c := make([]byte, n)
+		copy(c, bs)
+		select {
+		case outbox <- recv{c, addr}:
+		default:
+			if debug {
+				l.Debugln("dropping message")
+			}
+		}
+	}
+}

beacon/broadcast.go

@@ -6,16 +6,6 @@ package beacon
 
 import "net"
 
-type recv struct {
-	data []byte
-	src  net.Addr
-}
-
-type dst struct {
-	intf string
-	conn *net.UDPConn
-}
-
 type Broadcast struct {
 	conn   *net.UDPConn
 	port   int
@@ -36,7 +26,7 @@ func NewBroadcast(port int) (*Broadcast, error) {
 		outbox: make(chan recv, 16),
 	}
 
-	go b.reader()
+	go genericReader(b.conn, b.outbox)
 	go b.writer()
 
 	return b, nil
@@ -51,30 +41,6 @@ func (b *Broadcast) Recv() ([]byte, net.Addr) {
 	return recv.data, recv.src
 }
 
-func (b *Broadcast) reader() {
-	bs := make([]byte, 65536)
-	for {
-		n, addr, err := b.conn.ReadFrom(bs)
-		if err != nil {
-			l.Warnln("Broadcast read:", err)
-			return
-		}
-		if debug {
-			l.Debugf("recv %d bytes from %s", n, addr)
-		}
-
-		c := make([]byte, n)
-		copy(c, bs)
-		select {
-		case b.outbox <- recv{c, addr}:
-		default:
-			if debug {
-				l.Debugln("dropping message")
-			}
-		}
-	}
-}
-
 func (b *Broadcast) writer() {
 	for bs := range b.inbox {
 

beacon/multicast.go

@@ -0,0 +1,70 @@
+// Copyright (C) 2014 Jakob Borg and Contributors (see the CONTRIBUTORS file).
+// All rights reserved. Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+package beacon
+
+import "net"
+
+type Multicast struct {
+	conn   *net.UDPConn
+	addr   *net.UDPAddr
+	conns  []dst
+	inbox  chan []byte
+	outbox chan recv
+}
+
+func NewMulticast(addr string) (*Multicast, error) {
+	gaddr, err := net.ResolveUDPAddr("udp", addr)
+	if err != nil {
+		return nil, err
+	}
+	conn, err := net.ListenMulticastUDP("udp", nil, gaddr)
+	if err != nil {
+		return nil, err
+	}
+	b := &Multicast{
+		conn:   conn,
+		addr:   gaddr,
+		inbox:  make(chan []byte),
+		outbox: make(chan recv, 16),
+	}
+
+	go genericReader(b.conn, b.outbox)
+	go b.writer()
+
+	return b, nil
+}
+
+func (b *Multicast) Send(data []byte) {
+	b.inbox <- data
+}
+
+func (b *Multicast) Recv() ([]byte, net.Addr) {
+	recv := <-b.outbox
+	return recv.data, recv.src
+}
+
+func (b *Multicast) writer() {
+	for bs := range b.inbox {
+		intfs, err := net.Interfaces()
+		if err != nil {
+			l.Warnln("multicast interfaces:", err)
+			continue
+		}
+		for _, intf := range intfs {
+			if intf.Flags&net.FlagUp != 0 && intf.Flags&net.FlagMulticast != 0 {
+				addr := *b.addr
+				addr.Zone = intf.Name
+				_, err = b.conn.WriteTo(bs, &addr)
+				if err != nil {
+					if debug {
+						l.Debugln(err, "on write to", addr)
+					}
+				} else if debug {
+					l.Debugf("sent %d bytes to %s", len(bs), addr.String())
+				}
+			}
+		}
+	}
+}

cmd/syncthing/main.go

@@ -985,7 +985,7 @@ func setTCPOptions(conn *net.TCPConn) {
 }
 
 func discovery(extPort int) *discover.Discoverer {
-	disc, err := discover.NewDiscoverer(myID, cfg.Options.ListenAddress, cfg.Options.LocalAnnPort)
+	disc, err := discover.NewDiscoverer(myID, cfg.Options.ListenAddress, cfg.Options.LocalAnnPort, cfg.Options.LocalAnnMCAddr)
 	if err != nil {
 		l.Warnf("No discovery possible (%v)", err)
 		return nil

config/config.go

@@ -113,6 +113,7 @@ type OptionsConfiguration struct {
 	GlobalAnnEnabled   bool     `xml:"globalAnnounceEnabled" default:"true"`
 	LocalAnnEnabled    bool     `xml:"localAnnounceEnabled" default:"true"`
 	LocalAnnPort       int      `xml:"localAnnouncePort" default:"21025"`
+	LocalAnnMCAddr     string   `xml:"localAnnounceMCAddr" default:"[ff32::5222]:21026"`
 	ParallelRequests   int      `xml:"parallelRequests" default:"16"`
 	MaxSendKbps        int      `xml:"maxSendKbps"`
 	RescanIntervalS    int      `xml:"rescanIntervalS" default:"60"`

config/config_test.go

@@ -30,6 +30,7 @@ func TestDefaultValues(t *testing.T) {
 		GlobalAnnEnabled:   true,
 		LocalAnnEnabled:    true,
 		LocalAnnPort:       21025,
+		LocalAnnMCAddr:     "[ff32::5222]:21026",
 		ParallelRequests:   16,
 		MaxSendKbps:        0,
 		RescanIntervalS:    60,
@@ -200,6 +201,7 @@ func TestOverriddenValues(t *testing.T) {
         <globalAnnounceEnabled>false</globalAnnounceEnabled>
         <localAnnounceEnabled>false</localAnnounceEnabled>
         <localAnnouncePort>42123</localAnnouncePort>
+        <localAnnounceMCAddr>quux:3232</localAnnounceMCAddr>
         <parallelRequests>32</parallelRequests>
         <maxSendKbps>1234</maxSendKbps>
         <rescanIntervalS>600</rescanIntervalS>
@@ -218,6 +220,7 @@ func TestOverriddenValues(t *testing.T) {
 		GlobalAnnEnabled:   false,
 		LocalAnnEnabled:    false,
 		LocalAnnPort:       42123,
+		LocalAnnMCAddr:     "quux:3232",
 		ParallelRequests:   32,
 		MaxSendKbps:        1234,
 		RescanIntervalS:    600,

discover/discover.go

@@ -26,7 +26,8 @@ type Discoverer struct {
 	globalBcastIntv  time.Duration
 	errorRetryIntv   time.Duration
 	cacheLifetime    time.Duration
-	broadcastBeacon  *beacon.Broadcast
+	broadcastBeacon  beacon.Interface
+	multicastBeacon  beacon.Interface
 	registry         map[protocol.NodeID][]cacheEntry
 	registryLock     sync.RWMutex
 	extServer        string
@@ -54,11 +55,7 @@ var (
 // When we hit this many errors in succession, we stop.
 const maxErrors = 30
 
-func NewDiscoverer(id protocol.NodeID, addresses []string, localPort int) (*Discoverer, error) {
-	b, err := beacon.NewBroadcast(localPort)
-	if err != nil {
-		return nil, err
-	}
+func NewDiscoverer(id protocol.NodeID, addresses []string, localPort int, localMCAddr string) (*Discoverer, error) {
 	disc := &Discoverer{
 		myID:            id,
 		listenAddrs:     addresses,
@@ -66,11 +63,26 @@ func NewDiscoverer(id protocol.NodeID, addresses []string, localPort int) (*Disc
 		globalBcastIntv: 1800 * time.Second,
 		errorRetryIntv:  60 * time.Second,
 		cacheLifetime:   5 * time.Minute,
-		broadcastBeacon: b,
 		registry:        make(map[protocol.NodeID][]cacheEntry),
 	}
 
-	go disc.recvAnnouncements()
+	if localPort > 0 {
+		bb, err := beacon.NewBroadcast(localPort)
+		if err != nil {
+			return nil, err
+		}
+		disc.broadcastBeacon = bb
+		go disc.recvAnnouncements(bb)
+	}
+
+	if len(localMCAddr) > 0 {
+		mb, err := beacon.NewMulticast(localMCAddr)
+		if err != nil {
+			return nil, err
+		}
+		disc.multicastBeacon = mb
+		go disc.recvAnnouncements(mb)
+	}
 
 	return disc, nil
 }
@@ -187,7 +199,12 @@ func (d *Discoverer) sendLocalAnnouncements() {
 	msg := pkt.MarshalXDR()
 
 	for {
-		d.broadcastBeacon.Send(msg)
+		if d.multicastBeacon != nil {
+			d.multicastBeacon.Send(msg)
+		}
+		if d.broadcastBeacon != nil {
+			d.broadcastBeacon.Send(msg)
+		}
 
 		select {
 		case <-d.localBcastTick:
@@ -284,9 +301,9 @@ loop:
 	}
 }
 
-func (d *Discoverer) recvAnnouncements() {
+func (d *Discoverer) recvAnnouncements(b beacon.Interface) {
 	for {
-		buf, addr := d.broadcastBeacon.Recv()
+		buf, addr := b.Recv()
 
 		if debug {
 			l.Debugf("discover: read announcement from %s:\n%s", addr, hex.Dump(buf))

gui/index.html

@@ -614,10 +614,6 @@
                     </label>
                   </div>
                 </div>
-                <div class="form-group">
-                  <label translate for="LocalAnnPort">Local Discovery Port</label>
-                  <input ng-disabled="!tmpOptions.LocalAnnEnabled" id="LocalAnnPort" class="form-control" type="number" ng-model="tmpOptions.LocalAnnPort">
-                </div>
                 <div class="form-group">
                   <div class="checkbox">
                     <label>