From 9667a0a618a7a5bf407292800554d5eabc9f604b Mon Sep 17 00:00:00 2001
From: Audrius Butkevicius <audrius.butkevicius@gmail.com>
Date: Wed, 7 Jun 2017 10:16:14 +0200
Subject: [PATCH] lib/connections: Fix race (fixes #4177)

---
 lib/connections/kcp_listen.go | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/connections/kcp_listen.go b/lib/connections/kcp_listen.go
index c1f4f0bc8..b4a1fc485 100644
--- a/lib/connections/kcp_listen.go
+++ b/lib/connections/kcp_listen.go
@@ -187,7 +187,6 @@ func (t *kcpListener) stunRenewal(listener net.PacketConn) {
 	client := stun.NewClientWithConnection(listener)
 	client.SetSoftwareName("syncthing")
 
-	var uri url.URL
 	var natType stun.NATType
 	var extAddr *stun.Host
 	var err error
@@ -227,10 +226,12 @@ func (t *kcpListener) stunRenewal(listener net.PacketConn) {
 
 			for {
 				changed := false
-				uri = *t.uri
+
+				uri := *t.uri
 				uri.Host = extAddr.TransportAddr()
 
 				t.mut.Lock()
+
 				if t.address == nil || t.address.String() != uri.String() {
 					l.Infof("%s resolved external address %s (via %s)", t.uri, uri.String(), addr)
 					t.address = &uri