From 0d72e89ac4b719b212b0abaa3ac50109363670c2 Mon Sep 17 00:00:00 2001
From: William Banfield <wbanfield@gmail.com>
Date: Thu, 30 Sep 2021 13:40:21 -0400
Subject: [PATCH] recover on send on closed channel in statesync

---
 internal/statesync/reactor.go |  6 +++++-
 internal/statesync/syncer.go  | 10 +++++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/internal/statesync/reactor.go b/internal/statesync/reactor.go
index 73b9e0af1..84cd69c7c 100644
--- a/internal/statesync/reactor.go
+++ b/internal/statesync/reactor.go
@@ -902,7 +902,11 @@ func (r *Reactor) processPeerUpdate(peerUpdate p2p.PeerUpdate) {
 	case p2p.PeerStatusUp:
 		newProvider := NewBlockProvider(peerUpdate.NodeID, r.chainID, r.dispatcher)
 		r.providers[peerUpdate.NodeID] = newProvider
-		r.syncer.AddPeer(peerUpdate.NodeID)
+		err := r.syncer.AddPeer(peerUpdate.NodeID)
+		if err != nil {
+			r.Logger.Error("error adding peer to syncer", "error", err)
+			return
+		}
 		if sp, ok := r.stateProvider.(*stateProviderP2P); ok {
 			// we do this in a separate routine to not block whilst waiting for the light client to finish
 			// whatever call it's currently executing
diff --git a/internal/statesync/syncer.go b/internal/statesync/syncer.go
index 68bec6880..33838c51c 100644
--- a/internal/statesync/syncer.go
+++ b/internal/statesync/syncer.go
@@ -141,7 +141,14 @@ func (s *syncer) AddSnapshot(peerID types.NodeID, snapshot *snapshot) (bool, err
 
 // AddPeer adds a peer to the pool. For now we just keep it simple and send a
 // single request to discover snapshots, later we may want to do retries and stuff.
-func (s *syncer) AddPeer(peerID types.NodeID) {
+func (s *syncer) AddPeer(peerID types.NodeID) error {
+	var err error
+	defer func() {
+		if r := recover(); r != nil {
+			err = fmt.Errorf("panic sending peer snapshot request: %v", r)
+		}
+	}()
+
 	s.logger.Debug("Requesting snapshots from peer", "peer", peerID)
 
 	msg := p2p.Envelope{
@@ -153,6 +160,7 @@ func (s *syncer) AddPeer(peerID types.NodeID) {
 	case <-s.closeCh:
 	case s.snapshotCh <- msg:
 	}
+	return err
 }
 
 // RemovePeer removes a peer from the pool.