From 7924c7681528d7f95229d72c154c8cd35543577d Mon Sep 17 00:00:00 2001
From: Anton Kaliaev <anton.kalyaev@gmail.com>
Date: Tue, 2 Jul 2019 21:19:58 +0400
Subject: [PATCH] p2p: dial addrs which came from seed instead of calling
 ensurePeers (#3762)

Calling ensurePeers outside of ensurePeersRoutine can lead to nodes
disconnecting from us due to "sent next PEX request too soon" error.

Solution is to just dial addrs we got from src instead of calling
ensurePeers.

Refs #2093

Fixes #3338
---
 CHANGELOG_PENDING.md   |  2 ++
 p2p/pex/pex_reactor.go | 29 ++++++++++++++++++++++++-----
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG_PENDING.md b/CHANGELOG_PENDING.md
index 5dbc1ddb7..d913443a2 100644
--- a/CHANGELOG_PENDING.md
+++ b/CHANGELOG_PENDING.md
@@ -20,3 +20,5 @@
 - [abci] \#3809 Recover from application panics in `server/socket_server.go` to allow socket cleanup (@ruseinov)
 
 ### BUG FIXES:
+- [p2p] \#3338 Prevent "sent next PEX request too soon" errors by not calling
+  ensurePeers outside of ensurePeersRoutine
diff --git a/p2p/pex/pex_reactor.go b/p2p/pex/pex_reactor.go
index eabbc4d61..e0d7c0d72 100644
--- a/p2p/pex/pex_reactor.go
+++ b/p2p/pex/pex_reactor.go
@@ -340,6 +340,15 @@ func (r *PEXReactor) ReceiveAddrs(addrs []*p2p.NetAddress, src Peer) error {
 	if err != nil {
 		return err
 	}
+
+	srcIsSeed := false
+	for _, seedAddr := range r.seedAddrs {
+		if seedAddr.Equals(srcAddr) {
+			srcIsSeed = true
+			break
+		}
+	}
+
 	for _, netAddr := range addrs {
 		// Validate netAddr. Disconnect from a peer if it sends us invalid data.
 		if netAddr == nil {
@@ -365,13 +374,23 @@ func (r *PEXReactor) ReceiveAddrs(addrs []*p2p.NetAddress, src Peer) error {
 		}
 
 		// If this address came from a seed node, try to connect to it without
-		// waiting.
-		for _, seedAddr := range r.seedAddrs {
-			if seedAddr.Equals(srcAddr) {
-				r.ensurePeers()
-			}
+		// waiting (#2093)
+		if srcIsSeed {
+			r.Logger.Info("Will dial address, which came from seed", "addr", netAddr, "seed", srcAddr)
+			go func(addr *p2p.NetAddress) {
+				err := r.dialPeer(addr)
+				if err != nil {
+					switch err.(type) {
+					case errMaxAttemptsToDial, errTooEarlyToDial:
+						r.Logger.Debug(err.Error(), "addr", addr)
+					default:
+						r.Logger.Error(err.Error(), "addr", addr)
+					}
+				}
+			}(netAddr)
 		}
 	}
+
 	return nil
 }