From 9f784b3c316d557e45345044a96ec5443d7941c4 Mon Sep 17 00:00:00 2001
From: Bryan Boreham <bjboreham@gmail.com>
Date: Thu, 25 Jun 2015 12:22:53 +0100
Subject: [PATCH] Report errors in unicasting gossip

---
 ipam/allocator.go        |  4 ++--
 router/gossip_channel.go | 17 ++++++++++++-----
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/ipam/allocator.go b/ipam/allocator.go
index 8b609b96..98f36f3d 100644
--- a/ipam/allocator.go
+++ b/ipam/allocator.go
@@ -575,14 +575,14 @@ func (alloc *Allocator) propose() {
 	alloc.gossip.GossipBroadcast(alloc.Gossip())
 }
 
-func (alloc *Allocator) sendSpaceRequest(dest router.PeerName, r address.Range) {
+func (alloc *Allocator) sendSpaceRequest(dest router.PeerName, r address.Range) error {
 	buf := new(bytes.Buffer)
 	enc := gob.NewEncoder(buf)
 	if err := enc.Encode(r); err != nil {
 		panic(err)
 	}
 	msg := router.Concat([]byte{msgSpaceRequest}, buf.Bytes())
-	alloc.gossip.GossipUnicast(dest, msg)
+	return alloc.gossip.GossipUnicast(dest, msg)
 }
 
 func (alloc *Allocator) sendRingUpdate(dest router.PeerName) {
diff --git a/router/gossip_channel.go b/router/gossip_channel.go
index da7dc0ec..bbc177db 100644
--- a/router/gossip_channel.go
+++ b/router/gossip_channel.go
@@ -3,6 +3,7 @@ package router
 import (
 	"bytes"
 	"encoding/gob"
+	"fmt"
 	"log"
 	"sync"
 )
@@ -58,7 +59,10 @@ func (c *GossipChannel) deliverUnicast(srcName PeerName, origPayload []byte, dec
 		return err
 	}
 	if c.ourself.Name != destName {
-		return c.relayUnicast(destName, origPayload)
+		c.relayUnicast(destName, origPayload)
+		// ignore errors in passing on data; a problem between us and destination
+		// is not enough reason to break the connection from the source
+		return nil
 	}
 	var payload []byte
 	if err := dec.Decode(&payload); err != nil {
@@ -160,15 +164,18 @@ func (c *GossipChannel) GossipBroadcast(update GossipData) error {
 	return c.relayBroadcast(c.ourself.Name, update)
 }
 
-func (c *GossipChannel) relayUnicast(dstPeerName PeerName, buf []byte) error {
+func (c *GossipChannel) relayUnicast(dstPeerName PeerName, buf []byte) (err error) {
 	if relayPeerName, found := c.routes.UnicastAll(dstPeerName); !found {
-		c.log("unknown relay destination:", dstPeerName)
+		err = fmt.Errorf("unknown relay destination: %s", dstPeerName)
 	} else if conn, found := c.ourself.ConnectionTo(relayPeerName); !found {
-		c.log("unable to find connection to relay peer", relayPeerName)
+		err = fmt.Errorf("unable to find connection to relay peer %s", relayPeerName)
 	} else {
 		conn.(ProtocolSender).SendProtocolMsg(ProtocolMsg{ProtocolGossipUnicast, buf})
 	}
-	return nil
+	if err != nil {
+		c.log(err)
+	}
+	return err
 }
 
 func (c *GossipChannel) relayBroadcast(srcName PeerName, update GossipData) error {