From 716a8329c2cabb2885f5619f50dce947cc00a94c Mon Sep 17 00:00:00 2001
From: Audrius Butkevicius <audrius.butkevicius@gmail.com>
Date: Wed, 20 Aug 2014 00:00:21 +0100
Subject: [PATCH] Do not warn about failed IPv6 discovery

---
 cmd/syncthing/main.go | 12 ++++--------
 discover/discover.go  | 34 +++++++++++++++++++---------------
 2 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/cmd/syncthing/main.go b/cmd/syncthing/main.go
index 2d8cf60d5..85b309782 100644
--- a/cmd/syncthing/main.go
+++ b/cmd/syncthing/main.go
@@ -989,19 +989,15 @@ func setTCPOptions(conn *net.TCPConn) {
 }
 
 func discovery(extPort int) *discover.Discoverer {
-	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
-	}
+	disc := discover.NewDiscoverer(myID, cfg.Options.ListenAddress)
 
 	if cfg.Options.LocalAnnEnabled {
-		l.Infoln("Sending local discovery announcements")
-		disc.StartLocal()
+		l.Infoln("Starting local discovery announcements")
+		disc.StartLocal(cfg.Options.LocalAnnPort, cfg.Options.LocalAnnMCAddr)
 	}
 
 	if cfg.Options.GlobalAnnEnabled {
-		l.Infoln("Sending global discovery announcements")
+		l.Infoln("Starting global discovery announcements")
 		disc.StartGlobal(cfg.Options.GlobalAnnServer, uint16(extPort))
 	}
 
diff --git a/discover/discover.go b/discover/discover.go
index 901dc6e35..cfc20fdc0 100644
--- a/discover/discover.go
+++ b/discover/discover.go
@@ -55,8 +55,8 @@ var (
 // When we hit this many errors in succession, we stop.
 const maxErrors = 30
 
-func NewDiscoverer(id protocol.NodeID, addresses []string, localPort int, localMCAddr string) (*Discoverer, error) {
-	disc := &Discoverer{
+func NewDiscoverer(id protocol.NodeID, addresses []string) *Discoverer {
+	return &Discoverer{
 		myID:            id,
 		listenAddrs:     addresses,
 		localBcastIntv:  30 * time.Second,
@@ -65,32 +65,36 @@ func NewDiscoverer(id protocol.NodeID, addresses []string, localPort int, localM
 		cacheLifetime:   5 * time.Minute,
 		registry:        make(map[protocol.NodeID][]cacheEntry),
 	}
+}
 
+func (d *Discoverer) StartLocal(localPort int, localMCAddr string) {
 	if localPort > 0 {
 		bb, err := beacon.NewBroadcast(localPort)
 		if err != nil {
-			return nil, err
+			l.Infof("No IPv4 discovery possible (%v)", err)
+		} else {
+			d.broadcastBeacon = bb
+			go d.recvAnnouncements(bb)
 		}
-		disc.broadcastBeacon = bb
-		go disc.recvAnnouncements(bb)
 	}
 
 	if len(localMCAddr) > 0 {
 		mb, err := beacon.NewMulticast(localMCAddr)
 		if err != nil {
-			return nil, err
+			l.Infof("No IPv6 discovery possible (%v)", err)
+		} else {
+			d.multicastBeacon = mb
+			go d.recvAnnouncements(mb)
 		}
-		disc.multicastBeacon = mb
-		go disc.recvAnnouncements(mb)
 	}
 
-	return disc, nil
-}
-
-func (d *Discoverer) StartLocal() {
-	d.localBcastTick = time.Tick(d.localBcastIntv)
-	d.forcedBcastTick = make(chan time.Time)
-	go d.sendLocalAnnouncements()
+	if d.broadcastBeacon == nil && d.multicastBeacon == nil {
+		l.Warnln("No local discovery method available")
+	} else {
+		d.localBcastTick = time.Tick(d.localBcastIntv)
+		d.forcedBcastTick = make(chan time.Time)
+		go d.sendLocalAnnouncements()
+	}
 }
 
 func (d *Discoverer) StartGlobal(server string, extPort uint16) {