From f5ac34d755eb6975958108413c7802a782ca16c8 Mon Sep 17 00:00:00 2001
From: Tom Thorogood <me+github@tomthorogood.co.uk>
Date: Thu, 11 Jan 2018 00:07:59 +1030
Subject: [PATCH] Fix TCP Shutdown 'use of closed network connection' (#623)

The check for srv.started being false is in the wrong place, it should
be after Accept not after ReadTCP. If Shutdown is called, serveTCP will
currently return a 'use of closed network connection' error, which is
undesired.

This commit mirrors the behaviour of serveUDP with respect to Shutdown.
---
 server.go | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/server.go b/server.go
index b79abad5..b6ce5b5f 100644
--- a/server.go
+++ b/server.go
@@ -460,6 +460,12 @@ func (srv *Server) serveTCP(l net.Listener) error {
 	// deadline is not used here
 	for {
 		rw, err := l.Accept()
+		srv.lock.RLock()
+		if !srv.started {
+			srv.lock.RUnlock()
+			return nil
+		}
+		srv.lock.RUnlock()
 		if err != nil {
 			if neterr, ok := err.(net.Error); ok && neterr.Temporary() {
 				continue
@@ -467,12 +473,6 @@ func (srv *Server) serveTCP(l net.Listener) error {
 			return err
 		}
 		m, err := reader.ReadTCP(rw, rtimeout)
-		srv.lock.RLock()
-		if !srv.started {
-			srv.lock.RUnlock()
-			return nil
-		}
-		srv.lock.RUnlock()
 		if err != nil {
 			continue
 		}