Various gossipsub fixes (#827)

libp2p/protocols/pubsub/gossipsub/behavior.nim

@@ -130,6 +130,10 @@ proc handleGraft*(g: GossipSub,
 
       continue
 
+    if g.mesh.hasPeer(topic, peer):
+      trace "peer already in mesh", peer, topic
+      continue
+
     # Check backingOff
     # Ignore BackoffSlackTime here, since this only for outbound activity
     # and subtract a second time to avoid race conditions
@@ -176,6 +180,10 @@ proc handleGraft*(g: GossipSub,
           topicID: topic,
           peers: g.peerExchangeList(topic),
           backoff: g.parameters.pruneBackoff.seconds.uint64))
+
+        let backoff = Moment.fromNow(g.parameters.pruneBackoff)
+        g.backingOff
+          .mgetOrPut(topic, initTable[PeerId, Moment]())[peer.peerId] = backoff
     else:
       trace "peer grafting topic we're not interested in", peer, topic
       # gossip 1.1, we do not send a control message prune anymore

libp2p/protocols/pubsub/gossipsub/scoring.nim

@@ -295,11 +295,11 @@ proc rewardDelivered*(
 
     g.withPeerStats(peer.peerId) do (stats: var PeerStats):
       stats.topicInfos.withValue(tt, tstats):
-        if tstats[].inMesh:
-          if first:
-            tstats[].firstMessageDeliveries.addCapped(
-              1, topicParams.firstMessageDeliveriesCap)
+        if first:
+          tstats[].firstMessageDeliveries.addCapped(
+            1, topicParams.firstMessageDeliveriesCap)
 
+        if tstats[].inMesh:
           tstats[].meshMessageDeliveries.addCapped(
             1, topicParams.meshMessageDeliveriesCap)
       do: # make sure we don't loose this information