Change iteration over connection decoding to abort after the first error, and let the UnknownPeersError know which peer was unknown

peer_cache.go

@@ -177,24 +177,22 @@ func (cache *PeerCache) decodeUpdate(update []byte, router *Router) (newPeers ma
 		}
 	}
 
-	unknownPeers := false
 	for _, connsBuf := range decodedConns {
-		connsIterator(connsBuf, func(remoteNameByte []byte, _ string) {
+		err = connsIterator(connsBuf, func(remoteNameByte []byte, _ string) error {
 			remoteName := PeerNameFromBin(remoteNameByte)
 			if _, found := newPeers[remoteName]; found {
-				return
+				return nil
 			}
 			if _, found := cache.table[remoteName]; found {
-				return
+				return nil
 			}
 			// Update refers to a peer which we have no knowledge
 			// of. Thus we can't apply the update. Abort.
-			unknownPeers = true
+			return UnknownPeersError{remoteName}
 		})
-	}
-	if unknownPeers {
-		err = UnknownPeersError{}
-		return
+		if err != nil {
+			break
+		}
 	}
 	return
 }
@@ -282,7 +280,7 @@ func decodePeerNoConns(dec *gob.Decoder) (nameByte []byte, uid uint64, version u
 	return
 }
 
-func connsIterator(input []byte, fun func([]byte, string)) {
+func connsIterator(input []byte, fun func([]byte, string) error) error {
 	buf := new(bytes.Buffer)
 	buf.Write(input)
 	dec := gob.NewDecoder(buf)
@@ -290,22 +288,26 @@ func connsIterator(input []byte, fun func([]byte, string)) {
 		var nameByte []byte
 		err := dec.Decode(&nameByte)
 		if err == io.EOF {
-			return
+			return nil
 		}
 		checkFatal(err)
 		var foundAt string
 		checkFatal(dec.Decode(&foundAt))
-		fun(nameByte, string(foundAt))
+		if err = fun(nameByte, string(foundAt)); err != nil {
+			return err
+		}
 	}
+	return nil
 }
 
 func readConnsMap(peer *Peer, buf []byte, table map[PeerName]*Peer) map[PeerName]Connection {
 	conns := make(map[PeerName]Connection)
-	connsIterator(buf, func(nameByte []byte, remoteTCPAddr string) {
+	connsIterator(buf, func(nameByte []byte, remoteTCPAddr string) error {
 		name := PeerNameFromBin(nameByte)
 		remotePeer := table[name]
 		conn := NewRemoteConnection(peer, remotePeer, remoteTCPAddr)
 		conns[name] = conn
+		return nil
 	})
 	return conns
 }

types.go

@@ -123,6 +123,7 @@ type FrameTooBigError struct {
 }
 
 type UnknownPeersError struct {
+	Name PeerName
 }
 
 type NameCollisionError struct {

utils.go

@@ -39,7 +39,7 @@ func (ftbe FrameTooBigError) Error() string {
 }
 
 func (upe UnknownPeersError) Error() string {
-	return fmt.Sprint("Reference to unknown peers")
+	return fmt.Sprint("Reference to unknown peer: ", upe.Name)
 }
 
 func (nce NameCollisionError) Error() string {