From 771f64397fd8638e9a40a4b9ecc64a9b70d6f2e4 Mon Sep 17 00:00:00 2001
From: Maran <maran.hidskes@gmail.com>
Date: Tue, 10 Jun 2014 13:51:34 +0200
Subject: [PATCH] Stop peers when they don't respond to ping/pong. Might fix
 ethereum/go-ethereum#78

---
 peer.go | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/peer.go b/peer.go
index eed5bec30..9cc892d8b 100644
--- a/peer.go
+++ b/peer.go
@@ -18,6 +18,8 @@ const (
 	outputBufferSize = 50
 	// Current protocol version
 	ProtocolVersion = 17
+	// Interval for ping/pong message
+	pingPongTimer = 30 * time.Second
 )
 
 type DiscReason byte
@@ -243,7 +245,7 @@ func (p *Peer) writeMessage(msg *ethwire.Msg) {
 
 	err := ethwire.WriteMessage(p.conn, msg)
 	if err != nil {
-		ethutil.Config.Log.Debugln("Can't send message:", err)
+		ethutil.Config.Log.Debugln("[PEER] Can't send message:", err)
 		// Stop the client if there was an error writing to it
 		p.Stop()
 		return
@@ -253,7 +255,7 @@ func (p *Peer) writeMessage(msg *ethwire.Msg) {
 // Outbound message handler. Outbound messages are handled here
 func (p *Peer) HandleOutbound() {
 	// The ping timer. Makes sure that every 2 minutes a ping is send to the peer
-	pingTimer := time.NewTicker(30 * time.Second)
+	pingTimer := time.NewTicker(pingPongTimer)
 	serviceTimer := time.NewTicker(5 * time.Minute)
 
 out:
@@ -264,8 +266,14 @@ out:
 			p.writeMessage(msg)
 			p.lastSend = time.Now()
 
-		// Ping timer sends a ping to the peer each 2 minutes
+		// Ping timer
 		case <-pingTimer.C:
+			timeSince := time.Since(time.Unix(p.lastPong, 0))
+			if p.pingStartTime.IsZero() == false && timeSince > (pingPongTimer+10*time.Second) {
+				ethutil.Config.Log.Infof("[PEER] Peer did not respond to latest pong fast enough, it took %s, disconnecting.\n", timeSince)
+				p.Stop()
+				return
+			}
 			p.writeMessage(ethwire.NewMessage(ethwire.MsgPingTy, ""))
 			p.pingStartTime = time.Now()
 
@@ -563,6 +571,7 @@ func (p *Peer) Stop() {
 
 	// Pre-emptively remove the peer; don't wait for reaping. We already know it's dead if we are here
 	p.ethereum.RemovePeer(p)
+	ethutil.Config.Log.Debugln("[PEER] Stopped peer:", p.conn.RemoteAddr())
 }
 
 func (p *Peer) pushHandshake() error {