Remove stale reverse channel links

gumble/gumble/channel_links_regression_test.go

@@ -0,0 +1,27 @@
+package gumble
+
+import (
+	"testing"
+
+	"git.stormux.org/storm/barnard/gumble/gumble/MumbleProto"
+	"google.golang.org/protobuf/proto"
+)
+
+// Regression: a full channel-link update used to leave the removed peer's
+// reverse link behind, making the client report a link that no longer exists.
+func TestChannelStateFullLinksRemovesReverseLinks(t *testing.T) {
+	c := &Client{Config: NewConfig(), Channels: make(Channels)}
+	a, b, replacement := c.Channels.create(1), c.Channels.create(2), c.Channels.create(3)
+	a.Links[b.ID], b.Links[a.ID] = b, a
+	id := a.ID
+	data, _ := proto.Marshal(&MumbleProto.ChannelState{ChannelId: &id, Links: []uint32{replacement.ID}})
+	if err := c.handleChannelState(data); err != nil {
+		t.Fatal(err)
+	}
+	if _, ok := b.Links[a.ID]; ok {
+		t.Fatal("stale reciprocal link remains")
+	}
+	if replacement.Links[a.ID] != a {
+		t.Fatal("replacement reciprocal link missing")
+	}
+}

gumble/gumble/handlers.go

@@ -463,11 +463,16 @@ func (c *Client) handleChannelState(buffer []byte) error {
 			channel.Name = *packet.Name
 		}
 		if packet.Links != nil {
-			channel.Links = make(Channels)
+			// A full replacement must also remove our old reciprocal links.
+			for oldID, old := range channel.Links {
+				delete(old.Links, channel.ID)
+				delete(channel.Links, oldID)
+			}
 			event.Type |= ChannelChangeLinks
 			for _, channelID := range packet.Links {
-				if c := c.Channels[channelID]; c != nil {
+				if linked := c.Channels[channelID]; linked != nil {
-					channel.Links[channelID] = c
+					channel.Links[channelID] = linked
+					linked.Links[channel.ID] = channel
 				}
 			}
 		}