From de4adefafb22889ef3ebfaa55b08b537334c5571 Mon Sep 17 00:00:00 2001
From: vyzo <vyzo@hackzen.org>
Date: Tue, 28 Aug 2018 21:07:09 +0300
Subject: [PATCH 1/3] fix data race in ownership of RPC when piggybacking
 control messages.

---
 comm.go      | 16 ++++++++++++++++
 gossipsub.go |  9 +++++++++
 2 files changed, 25 insertions(+)

diff --git a/comm.go b/comm.go
index 182e992..9c7487a 100644
--- a/comm.go
+++ b/comm.go
@@ -122,3 +122,19 @@ func rpcWithControl(msgs []*pb.Message,
 		},
 	}
 }
+
+func copyRPC(rpc *RPC) *RPC {
+	return &RPC{
+		RPC: pb.RPC{
+			Subscriptions: rpc.Subscriptions,
+			Publish:       rpc.Publish,
+			Control: &pb.ControlMessage{
+				Ihave: rpc.Control.Ihave,
+				Iwant: rpc.Control.Iwant,
+				Graft: rpc.Control.Graft,
+				Prune: rpc.Control.Prune,
+			},
+		},
+		from: rpc.from,
+	}
+}
diff --git a/gossipsub.go b/gossipsub.go
index 700120b..563b94e 100644
--- a/gossipsub.go
+++ b/gossipsub.go
@@ -308,9 +308,14 @@ func (gs *GossipSubRouter) sendPrune(p peer.ID, topic string) {
 }
 
 func (gs *GossipSubRouter) sendRPC(p peer.ID, out *RPC) {
+	// do we own the RPC?
+	own := false
+
 	// piggyback cotrol message retries
 	ctl, ok := gs.control[p]
 	if ok {
+		out = copyRPC(out)
+		own = true
 		gs.piggybackControl(p, out, ctl)
 		delete(gs.control, p)
 	}
@@ -318,6 +323,10 @@ func (gs *GossipSubRouter) sendRPC(p peer.ID, out *RPC) {
 	// piggyback gossip
 	ihave, ok := gs.gossip[p]
 	if ok {
+		if !own {
+			out = copyRPC(out)
+			own = true
+		}
 		gs.piggybackGossip(p, out, ihave)
 		delete(gs.gossip, p)
 	}

From 73b338aa6dbca0dfab73fe9d185774707b2e06e9 Mon Sep 17 00:00:00 2001
From: vyzo <vyzo@hackzen.org>
Date: Tue, 28 Aug 2018 21:17:00 +0300
Subject: [PATCH 2/3] fix nil pointer dereference in copyRPC

---
 comm.go | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/comm.go b/comm.go
index 9c7487a..f679fc4 100644
--- a/comm.go
+++ b/comm.go
@@ -124,17 +124,20 @@ func rpcWithControl(msgs []*pb.Message,
 }
 
 func copyRPC(rpc *RPC) *RPC {
-	return &RPC{
+	res := &RPC{
 		RPC: pb.RPC{
 			Subscriptions: rpc.Subscriptions,
 			Publish:       rpc.Publish,
-			Control: &pb.ControlMessage{
-				Ihave: rpc.Control.Ihave,
-				Iwant: rpc.Control.Iwant,
-				Graft: rpc.Control.Graft,
-				Prune: rpc.Control.Prune,
-			},
 		},
 		from: rpc.from,
 	}
+	if rpc.Control != nil {
+		res.Control = &pb.ControlMessage{
+			Ihave: rpc.Control.Ihave,
+			Iwant: rpc.Control.Iwant,
+			Graft: rpc.Control.Graft,
+			Prune: rpc.Control.Prune,
+		}
+	}
+	return res
 }

From a3003697f666db06486b801fc9b3ed0bdf3305a6 Mon Sep 17 00:00:00 2001
From: vyzo <vyzo@hackzen.org>
Date: Tue, 28 Aug 2018 21:35:00 +0300
Subject: [PATCH 3/3] more idiomatic copyRPC

---
 comm.go | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/comm.go b/comm.go
index f679fc4..fded9a8 100644
--- a/comm.go
+++ b/comm.go
@@ -124,20 +124,11 @@ func rpcWithControl(msgs []*pb.Message,
 }
 
 func copyRPC(rpc *RPC) *RPC {
-	res := &RPC{
-		RPC: pb.RPC{
-			Subscriptions: rpc.Subscriptions,
-			Publish:       rpc.Publish,
-		},
-		from: rpc.from,
-	}
+	res := new(RPC)
+	*res = *rpc
 	if rpc.Control != nil {
-		res.Control = &pb.ControlMessage{
-			Ihave: rpc.Control.Ihave,
-			Iwant: rpc.Control.Iwant,
-			Graft: rpc.Control.Graft,
-			Prune: rpc.Control.Prune,
-		}
+		res.Control = new(pb.ControlMessage)
+		*res.Control = *rpc.Control
 	}
 	return res
 }