From 9f301964ed74316de7796c0cbd9728190ac2fdda Mon Sep 17 00:00:00 2001
From: Giovanni Petrantoni <7008900+sinkingsugar@users.noreply.github.com>
Date: Wed, 28 Apr 2021 10:03:03 +0900
Subject: [PATCH] fix control messages (#566)

* remove unused control graft check in handleControl

* avoid sending empty Iwant messages
---
 libp2p/protocols/pubsub/gossipsub.nim | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/libp2p/protocols/pubsub/gossipsub.nim b/libp2p/protocols/pubsub/gossipsub.nim
index 54e07f052..b44c1842d 100644
--- a/libp2p/protocols/pubsub/gossipsub.nim
+++ b/libp2p/protocols/pubsub/gossipsub.nim
@@ -247,12 +247,13 @@ proc handleControl(g: GossipSub, peer: PubSubPeer, rpcMsg: RPCMsg) =
     g.handlePrune(peer, control.prune)
 
     var respControl: ControlMessage
-    respControl.iwant.add(g.handleIHave(peer, control.ihave))
+    let iwant = g.handleIHave(peer, control.ihave)
+    if iwant.messageIDs.len > 0:
+      respControl.iwant.add(iwant)
     respControl.prune.add(g.handleGraft(peer, control.graft))
     let messages = g.handleIWant(peer, control.iwant)
 
     if
-      respControl.graft.len > 0 or
       respControl.prune.len > 0 or
       respControl.iwant.len > 0 or
       messages.len > 0:
@@ -264,12 +265,15 @@ proc handleControl(g: GossipSub, peer: PubSubPeer, rpcMsg: RPCMsg) =
             libp2p_pubsub_broadcast_messages.inc(labelValues = [topic])
           else:
             libp2p_pubsub_broadcast_messages.inc(labelValues = ["generic"])
+
       libp2p_pubsub_broadcast_iwant.inc(respControl.iwant.len.int64)
+
       for prune in respControl.prune:
         if g.knownTopics.contains(prune.topicID):
           libp2p_pubsub_broadcast_prune.inc(labelValues = [prune.topicID])
         else:
           libp2p_pubsub_broadcast_prune.inc(labelValues = ["generic"])
+
       trace "sending control message", msg = shortLog(respControl), peer
       g.send(
         peer,