From f80410bf59312259ba18fd91cccc4e3d31fa14d8 Mon Sep 17 00:00:00 2001
From: Matthias Radestock <matthias.radestock@gmail.com>
Date: Sun, 5 Apr 2015 10:29:01 +0100
Subject: [PATCH] switch to gossip broadcast for topology updates

---
 router/gossip.go     | 1 +
 router/local_peer.go | 9 +--------
 router/protocol.go   | 2 +-
 router/router.go     | 6 +++++-
 4 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/router/gossip.go b/router/gossip.go
index df6ad30a..96f4abe8 100644
--- a/router/gossip.go
+++ b/router/gossip.go
@@ -269,6 +269,7 @@ func (c *GossipChannel) relayBroadcast(srcName PeerName, update GossipData) erro
 }
 
 func (c *GossipChannel) sendBroadcast(srcName PeerName, update GossipData) {
+	c.ourself.Router.Routes.EnsureRecalculated()
 	nextHops := c.ourself.Router.Routes.BroadcastAll(srcName)
 	if len(nextHops) == 0 {
 		return
diff --git a/router/local_peer.go b/router/local_peer.go
index dfde0493..7346c594 100644
--- a/router/local_peer.go
+++ b/router/local_peer.go
@@ -241,14 +241,7 @@ func (peer *LocalPeer) handleDeleteConnection(conn Connection) {
 
 func (peer *LocalPeer) broadcastPeerUpdate(peers ...*Peer) {
 	peer.Router.Routes.Recalculate()
-	// TODO We should just be invoking TopologyGossip.GossipBroadcast
-	// here, but route calculation is asynchronous and in this
-	// particular case would likely result in the broadcast not
-	// reaching all peers. So instead we slightly break the Gossip
-	// abstraction (hence the cast) and send a regular update. This is
-	// less efficient though since it will almost certainly reach
-	// peers more than once.
-	peer.Router.TopologyGossip.(*GossipChannel).Send(NewTopologyGossipData(peer.Router.Peers, append(peers, peer.Peer)...))
+	peer.Router.TopologyGossip.GossipBroadcast(NewTopologyGossipData(peer.Router.Peers, append(peers, peer.Peer)...))
 }
 
 func (peer *LocalPeer) checkConnectionLimit() error {
diff --git a/router/protocol.go b/router/protocol.go
index 9184512c..b9bb9f29 100644
--- a/router/protocol.go
+++ b/router/protocol.go
@@ -2,7 +2,7 @@ package router
 
 const (
 	Protocol        = "weave"
-	ProtocolVersion = 14
+	ProtocolVersion = 15
 )
 
 type ProtocolTag byte
diff --git a/router/router.go b/router/router.go
index 5ba48d7c..2eb9af36 100644
--- a/router/router.go
+++ b/router/router.go
@@ -378,7 +378,11 @@ func (router *Router) OnGossipUnicast(sender PeerName, msg []byte) error {
 }
 
 func (router *Router) OnGossipBroadcast(update []byte) (GossipData, error) {
-	return nil, fmt.Errorf("unexpected topology gossip broadcast: %v", update)
+	origUpdate, _, err := router.applyTopologyUpdate(update)
+	if err != nil || len(origUpdate) == 0 {
+		return nil, err
+	}
+	return &TopologyGossipData{peers: router.Peers, update: origUpdate}, nil
 }
 
 func (router *Router) Gossip() GossipData {