Fix local announce (IPv6 multicast, include all listen addresses)

cmd/syncthing/main.go

@@ -14,7 +14,6 @@ import (
 	"path"
 	"runtime"
 	"runtime/debug"
-	"strconv"
 	"strings"
 	"time"
 
@@ -263,7 +262,7 @@ func main() {
 	if verbose {
 		infoln("Attempting to connect to other nodes")
 	}
-	disc := discovery(cfg.Options.ListenAddress[0])
+	disc := discovery()
 	go connect(myID, disc, m, tlsCfg, connOpts)
 
 	// Routine to pull blocks from other nodes to synchronize the local
@@ -452,24 +451,20 @@ listen:
 	}
 }
 
-func discovery(addr string) *discover.Discoverer {
+func discovery() *discover.Discoverer {
-	_, portstr, err := net.SplitHostPort(addr)
-	fatalErr(err)
-	port, _ := strconv.Atoi(portstr)
-
 	if !cfg.Options.LocalAnnEnabled {
-		port = -1
+		return nil
-	} else if verbose {
-		infoln("Sending local discovery announcements")
 	}
 
+	infoln("Sending local discovery announcements")
+
 	if !cfg.Options.GlobalAnnEnabled {
 		cfg.Options.GlobalAnnServer = ""
 	} else if verbose {
 		infoln("Sending external discovery announcements")
 	}
 
-	disc, err := discover.NewDiscoverer(myID, port, cfg.Options.GlobalAnnServer)
+	disc, err := discover.NewDiscoverer(myID, cfg.Options.ListenAddress, cfg.Options.GlobalAnnServer)
 
 	if err != nil {
 		warnf("No discovery possible (%v)", err)

discover/discover.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"sync"
 	"time"
+	"code.google.com/p/go.net/ipv6"
 
 	"github.com/calmh/syncthing/buffers"
 )
@@ -19,14 +20,16 @@ const (
 
 type Discoverer struct {
 	MyID             string
-	ListenPort       int
+	ListenAddresses  []string
 	BroadcastIntv    time.Duration
 	ExtBroadcastIntv time.Duration
 
-	conn         *net.UDPConn
+	conn         *ipv6.PacketConn
+	intfs        []*net.Interface
 	registry     map[string][]string
 	registryLock sync.RWMutex
 	extServer    string
+	group        *net.UDPAddr
 
 	localBroadcastTick  <-chan time.Time
 	forcedBroadcastTick chan time.Time
@@ -41,113 +44,114 @@ var (
 // When we hit this many errors in succession, we stop.
 const maxErrors = 30
 
-func NewDiscoverer(id string, port int, extServer string) (*Discoverer, error) {
+func NewDiscoverer(id string, addresses []string, extServer string) (*Discoverer, error) {
-	local := &net.UDPAddr{IP: nil, Port: AnnouncementPort}
+	disc := &Discoverer{
-	conn, err := net.ListenUDP("udp", local)
+		MyID:             id,
+		ListenAddresses:  addresses,
+		BroadcastIntv:    30 * time.Second,
+		ExtBroadcastIntv: 1800 * time.Second,
+		registry:         make(map[string][]string),
+		extServer:        extServer,
+		group:            &net.UDPAddr{IP: net.ParseIP("ff02::2012:1025"), Port: AnnouncementPort},
+	}
+
+	// Listen on a multicast socket. This enables sharing the socket, i.e.
+	// other instances of syncting on the same box can listen on the same
+	// group/port.
+
+	conn, err := net.ListenPacket("udp6", fmt.Sprintf("[ff02::]:%d", AnnouncementPort))
 	if err != nil {
 		return nil, err
 	}
+	disc.conn = ipv6.NewPacketConn(conn)
 
-	disc := &Discoverer{
+	// Join the multicast group on as many interfaces as possible. Remember
-		MyID:             id,
+	// which those were.
-		ListenPort:       port,
-		BroadcastIntv:    30 * time.Second,
-		ExtBroadcastIntv: 1800 * time.Second,
 
-		conn:      conn,
+	intfs, err := net.Interfaces()
-		registry:  make(map[string][]string),
+	if err != nil {
-		extServer: extServer,
+		log.Printf("discover/interfaces: %v; no local announcements", err)
+		conn.Close()
+		return nil, err
 	}
 
+	for _, intf := range intfs {
+		intf := intf
+		addrs, err := intf.Addrs()
+		if err == nil && len(addrs) > 0 && intf.Flags&net.FlagMulticast != 0 && intf.Flags&net.FlagUp != 0 {
+			if err := disc.conn.JoinGroup(&intf, disc.group); err != nil {
+				if debug {
+					dlog.Printf("%v; not joining on %s", err, intf.Name)
+				}
+			} else {
+				disc.intfs = append(disc.intfs, &intf)
+			}
+		}
+	}
+
+	// Receive announcements sent to the local multicast group.
+
 	go disc.recvAnnouncements()
 
-	if disc.ListenPort > 0 {
+	// If we got a list of addresses that we listen on, announce those
+	// locally.
+
+	if len(disc.ListenAddresses) > 0 {
 		disc.localBroadcastTick = time.Tick(disc.BroadcastIntv)
 		disc.forcedBroadcastTick = make(chan time.Time)
-		go disc.sendAnnouncements()
+		go disc.sendLocalAnnouncements()
-	}
+
-	if len(disc.extServer) > 0 {
+		// If we have an external server address, also announce to that
-		go disc.sendExtAnnouncements()
+		// server.
+
+		if len(disc.extServer) > 0 {
+			go disc.sendExternalAnnouncements()
+		}
 	}
 
 	return disc, nil
 }
 
-func (d *Discoverer) sendAnnouncements() {
+func (d *Discoverer) announcementPkt() []byte {
-	var pkt = AnnounceV2{AnnouncementMagicV2, d.MyID, []Address{{nil, 22000}}}
+	var addrs []Address
-	var buf = pkt.MarshalXDR()
+	for _, astr := range d.ListenAddresses {
+		addr, err := net.ResolveTCPAddr("tcp", astr)
+		if err != nil {
+			log.Printf("discover/announcement: %v: not announcing %s", err, astr)
+			continue
+		} else if debug {
+			dlog.Printf("announcing %s: %#v", astr, addr)
+		}
+		if len(addr.IP) == 0 || addr.IP.IsUnspecified() {
+			addrs = append(addrs, Address{Port: uint16(addr.Port)})
+		} else if bs := addr.IP.To4(); bs != nil {
+			addrs = append(addrs, Address{IP: bs, Port: uint16(addr.Port)})
+		} else if bs := addr.IP.To16(); bs != nil {
+			addrs = append(addrs, Address{IP: bs, Port: uint16(addr.Port)})
+		}
+	}
+	var pkt = AnnounceV2{
+		Magic:     AnnouncementMagicV2,
+		NodeID:    d.MyID,
+		Addresses: addrs,
+	}
+	return pkt.MarshalXDR()
+}
+
+func (d *Discoverer) sendLocalAnnouncements() {
+	var buf = d.announcementPkt()
 	var errCounter = 0
 	var err error
 
-	remote := &net.UDPAddr{
+	wcm := ipv6.ControlMessage{HopLimit: 1}
-		IP:   net.IP{255, 255, 255, 255},
-		Port: AnnouncementPort,
-	}
-
 	for errCounter < maxErrors {
-		intfs, err := net.Interfaces()
+		for _, intf := range d.intfs {
-		if err != nil {
+			wcm.IfIndex = intf.Index
-			log.Printf("discover/listInterfaces: %v; no local announcements", err)
+			if _, err = d.conn.WriteTo(buf, &wcm, d.group); err != nil {
-			return
+				log.Printf("discover/sendLocalAnnouncements: on %s: %v; no local announcement", intf.Name, err)
-		}
+				errCounter++
-
+				continue
-		for _, intf := range intfs {
+			} else {
-			if intf.Flags&(net.FlagBroadcast|net.FlagLoopback) == net.FlagBroadcast {
-				addrs, err := intf.Addrs()
-				if err != nil {
-					log.Println("discover/listAddrs: warning:", err)
-					errCounter++
-					continue
-				}
-
-				var srcAddr string
-				for _, addr := range addrs {
-					if strings.Contains(addr.String(), ".") {
-						// Found an IPv4 adress
-						parts := strings.Split(addr.String(), "/")
-						srcAddr = parts[0]
-						break
-					}
-				}
-				if len(srcAddr) == 0 {
-					if debug {
-						dlog.Println("no source address found on interface", intf.Name)
-					}
-					continue
-				}
-
-				iaddr, err := net.ResolveUDPAddr("udp4", srcAddr+":0")
-				if err != nil {
-					log.Println("discover/resolve: warning:", err)
-					errCounter++
-					continue
-				}
-
-				conn, err := net.ListenUDP("udp4", iaddr)
-				if err != nil {
-					log.Println("discover/listen: warning:", err)
-					errCounter++
-					continue
-				}
-
-				if debug {
-					dlog.Println("send announcement from", conn.LocalAddr(), "to", remote, "on", intf.Name)
-				}
-
-				_, err = conn.WriteTo(buf, remote)
-				if err != nil {
-					// Some interfaces don't seem to support broadcast even though the flags claims they do, i.e. vmnet
-					conn.Close()
-
-					if debug {
-						log.Println(err)
-					}
-
-					errCounter++
-					continue
-				}
-
-				conn.Close()
 				errCounter = 0
 			}
 		}
@@ -157,25 +161,29 @@ func (d *Discoverer) sendAnnouncements() {
 		case <-d.forcedBroadcastTick:
 		}
 	}
-	log.Println("discover/write: local: stopping due to too many errors:", err)
 }
 
-func (d *Discoverer) sendExtAnnouncements() {
+func (d *Discoverer) sendExternalAnnouncements() {
 	remote, err := net.ResolveUDPAddr("udp", d.extServer)
 	if err != nil {
 		log.Printf("discover/external: %v; no external announcements", err)
 		return
 	}
 
-	var pkt = AnnounceV2{AnnouncementMagicV2, d.MyID, []Address{{nil, 22000}}}
+	conn, err := net.ListenUDP("udp", nil)
-	var buf = pkt.MarshalXDR()
+	if err != nil {
+		log.Printf("discover/external: %v; no external announcements", err)
+		return
+	}
+
+	var buf = d.announcementPkt()
 	var errCounter = 0
 
 	for errCounter < maxErrors {
 		if debug {
 			dlog.Println("send announcement -> ", remote)
 		}
-		_, err = d.conn.WriteTo(buf, remote)
+		_, err = conn.WriteTo(buf, remote)
 		if err != nil {
 			log.Println("discover/write: warning:", err)
 			errCounter++
@@ -192,7 +200,7 @@ func (d *Discoverer) recvAnnouncements() {
 	var errCounter = 0
 	var err error
 	for errCounter < maxErrors {
-		n, addr, err := d.conn.ReadFromUDP(buf)
+		n, _, addr, err := d.conn.ReadFrom(buf)
 		if err != nil {
 			errCounter++
 			time.Sleep(time.Second)
@@ -224,7 +232,9 @@ func (d *Discoverer) recvAnnouncements() {
 				if len(a.IP) > 0 {
 					nodeAddr = fmt.Sprintf("%s:%d", ipStr(a.IP), a.Port)
 				} else {
-					nodeAddr = fmt.Sprintf("%s:%d", addr.IP.String(), a.Port)
+					ua := addr.(*net.UDPAddr)
+					ua.Port = int(a.Port)
+					nodeAddr = ua.String()
 				}
 				addrs = append(addrs, nodeAddr)
 			}

integration/h1/config.xml

@@ -1,13 +1,13 @@
 <configuration version="1">
     <repository directory="s1">
         <node id="I6KAH7666SLLL5PFXSOAUFJCDZYAOMLEKCP2GB3BV5RQST3PSROA" name="s1">
-            <address>127.0.0.1:22001</address>
+            <address>dynamic</address>
         </node>
         <node id="JMFJCXBGZDE4BOCJE3VF65GYZNAIVJRET3J6HMRAUQIGJOFKNHMQ" name="s2">
-            <address>127.0.0.1:22002</address>
+            <address>dynamic</address>
         </node>
         <node id="373HSRPQLPNLIJYKZVQFP4PKZ6R2ZE6K3YD442UJHBGBQGWWXAHA" name="s3">
-            <address>127.0.0.1:22003</address>
+            <address>dynamic</address>
         </node>
     </repository>
     <options>
@@ -19,7 +19,7 @@
         <guiAddress>127.0.0.1:8081</guiAddress>
         <globalAnnounceServer>announce.syncthing.net:22025</globalAnnounceServer>
         <globalAnnounceEnabled>false</globalAnnounceEnabled>
-        <localAnnounceEnabled>false</localAnnounceEnabled>
+        <localAnnounceEnabled>true</localAnnounceEnabled>
         <parallelRequests>16</parallelRequests>
         <maxSendKbps>0</maxSendKbps>
         <rescanIntervalS>60</rescanIntervalS>

integration/h2/config.xml

@@ -1,17 +1,17 @@
 <configuration version="1">
     <repository directory="s2">
         <node id="I6KAH7666SLLL5PFXSOAUFJCDZYAOMLEKCP2GB3BV5RQST3PSROA" name="s1">
-            <address>127.0.0.1:22001</address>
+            <address>dynamic</address>
         </node>
         <node id="JMFJCXBGZDE4BOCJE3VF65GYZNAIVJRET3J6HMRAUQIGJOFKNHMQ" name="s2">
-            <address>127.0.0.1:22002</address>
+            <address>dynamic</address>
         </node>
         <node id="373HSRPQLPNLIJYKZVQFP4PKZ6R2ZE6K3YD442UJHBGBQGWWXAHA" name="s3">
-            <address>127.0.0.1:22003</address>
+            <address>dynamic</address>
         </node>
     </repository>
     <options>
-        <listenAddress>127.0.0.2:22002</listenAddress>
+        <listenAddress>127.0.0.1:22002</listenAddress>
         <readOnly>false</readOnly>
         <allowDelete>true</allowDelete>
         <followSymlinks>true</followSymlinks>
@@ -19,7 +19,7 @@
         <guiAddress>127.0.0.1:8082</guiAddress>
         <globalAnnounceServer>announce.syncthing.net:22025</globalAnnounceServer>
         <globalAnnounceEnabled>false</globalAnnounceEnabled>
-        <localAnnounceEnabled>false</localAnnounceEnabled>
+        <localAnnounceEnabled>true</localAnnounceEnabled>
         <parallelRequests>16</parallelRequests>
         <maxSendKbps>0</maxSendKbps>
         <rescanIntervalS>60</rescanIntervalS>

integration/h3/config.xml

@@ -1,13 +1,13 @@
 <configuration version="1">
     <repository directory="s3">
         <node id="I6KAH7666SLLL5PFXSOAUFJCDZYAOMLEKCP2GB3BV5RQST3PSROA" name="s1">
-            <address>127.0.0.1:22001</address>
+            <address>dynamic</address>
         </node>
         <node id="JMFJCXBGZDE4BOCJE3VF65GYZNAIVJRET3J6HMRAUQIGJOFKNHMQ" name="s2">
-            <address>127.0.0.1:22002</address>
+            <address>dynamic</address>
         </node>
         <node id="373HSRPQLPNLIJYKZVQFP4PKZ6R2ZE6K3YD442UJHBGBQGWWXAHA" name="s3">
-            <address>127.0.0.1:22003</address>
+            <address>dynamic</address>
         </node>
     </repository>
     <options>
@@ -19,7 +19,7 @@
         <guiAddress>127.0.0.1:8083</guiAddress>
         <globalAnnounceServer>announce.syncthing.net:22025</globalAnnounceServer>
         <globalAnnounceEnabled>false</globalAnnounceEnabled>
-        <localAnnounceEnabled>false</localAnnounceEnabled>
+        <localAnnounceEnabled>true</localAnnounceEnabled>
         <parallelRequests>16</parallelRequests>
         <maxSendKbps>0</maxSendKbps>
         <rescanIntervalS>60</rescanIntervalS>