From e52bfe3a51a46057cb5735eb2f845b0994ac9e6b Mon Sep 17 00:00:00 2001
From: NIC619 <twedusuck@gmail.com>
Date: Thu, 18 Jul 2019 22:37:44 +0800
Subject: [PATCH] Fix: Respond GRAFT with PRUNE if not subscribed to the topic

---
 libp2p/pubsub/gossipsub.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libp2p/pubsub/gossipsub.py b/libp2p/pubsub/gossipsub.py
index 01576ae..f1d057c 100644
--- a/libp2p/pubsub/gossipsub.py
+++ b/libp2p/pubsub/gossipsub.py
@@ -462,7 +462,8 @@ class GossipSub(IPubsubRouter):
         if topic in self.mesh:
             self.mesh[topic].append(from_id_str)
         else:
-            self.mesh[topic] = [from_id_str]
+            # Respond with PRUNE if not subscribed to the topic
+            await self.emit_prune(topic, sender_peer_id)
 
     async def handle_prune(self, prune_msg, sender_peer_id):
         topic = prune_msg.topicID