From 8c3146aa4fc2be64a1aad8a2e4eb4db71065dfc5 Mon Sep 17 00:00:00 2001
From: "Y.Horie" <u5.horie@gmail.com>
Date: Tue, 21 Jun 2022 04:42:05 +0900
Subject: [PATCH] Consolidate TCPKeepalive in server.Serve (#1320) (#1324)

---
 server.go | 71 ++++++++++++++++---------------------------------------
 1 file changed, 21 insertions(+), 50 deletions(-)

diff --git a/server.go b/server.go
index 5e10887444..3c9045501a 100644
--- a/server.go
+++ b/server.go
@@ -1554,34 +1554,6 @@ func (s *Server) getNextProto(c net.Conn) (proto string, err error) {
 	return
 }
 
-// tcpKeepAliveListener sets TCP keep-alive timeouts on accepted
-// connections. It's used by ListenAndServe, ListenAndServeTLS and
-// ListenAndServeTLSEmbed so dead TCP connections (e.g. closing laptop mid-download)
-// eventually go away.
-type tcpKeepaliveListener struct {
-	*net.TCPListener
-	keepalive       bool
-	keepalivePeriod time.Duration
-}
-
-func (ln tcpKeepaliveListener) Accept() (net.Conn, error) {
-	tc, err := ln.AcceptTCP()
-	if err != nil {
-		return nil, err
-	}
-	if err := tc.SetKeepAlive(ln.keepalive); err != nil {
-		tc.Close() //nolint:errcheck
-		return nil, err
-	}
-	if ln.keepalivePeriod > 0 {
-		if err := tc.SetKeepAlivePeriod(ln.keepalivePeriod); err != nil {
-			tc.Close() //nolint:errcheck
-			return nil, err
-		}
-	}
-	return tc, nil
-}
-
 // ListenAndServe serves HTTP requests from the given TCP4 addr.
 //
 // Pass custom listener to Serve if you need listening on non-TCP4 media
@@ -1593,13 +1565,6 @@ func (s *Server) ListenAndServe(addr string) error {
 	if err != nil {
 		return err
 	}
-	if tcpln, ok := ln.(*net.TCPListener); ok {
-		return s.Serve(tcpKeepaliveListener{
-			TCPListener:     tcpln,
-			keepalive:       s.TCPKeepalive,
-			keepalivePeriod: s.TCPKeepalivePeriod,
-		})
-	}
 	return s.Serve(ln)
 }
 
@@ -1638,13 +1603,6 @@ func (s *Server) ListenAndServeTLS(addr, certFile, keyFile string) error {
 	if err != nil {
 		return err
 	}
-	if tcpln, ok := ln.(*net.TCPListener); ok {
-		return s.ServeTLS(tcpKeepaliveListener{
-			TCPListener:     tcpln,
-			keepalive:       s.TCPKeepalive,
-			keepalivePeriod: s.TCPKeepalivePeriod,
-		}, certFile, keyFile)
-	}
 	return s.ServeTLS(ln, certFile, keyFile)
 }
 
@@ -1664,13 +1622,6 @@ func (s *Server) ListenAndServeTLSEmbed(addr string, certData, keyData []byte) e
 	if err != nil {
 		return err
 	}
-	if tcpln, ok := ln.(*net.TCPListener); ok {
-		return s.ServeTLSEmbed(tcpKeepaliveListener{
-			TCPListener:     tcpln,
-			keepalive:       s.TCPKeepalive,
-			keepalivePeriod: s.TCPKeepalivePeriod,
-		}, certData, keyData)
-	}
 	return s.ServeTLSEmbed(ln, certData, keyData)
 }
 
@@ -1910,7 +1861,27 @@ func (s *Server) Shutdown() error {
 
 func acceptConn(s *Server, ln net.Listener, lastPerIPErrorTime *time.Time) (net.Conn, error) {
 	for {
-		c, err := ln.Accept()
+		var c net.Conn
+		var err error
+		if tl, ok := ln.(*net.TCPListener); ok && s.TCPKeepalive {
+			tc, err := tl.AcceptTCP()
+			if err != nil {
+				return nil, err
+			}
+			if err := tc.SetKeepAlive(s.TCPKeepalive); err != nil {
+				tc.Close() //nolint:errcheck
+				return nil, err
+			}
+			if s.TCPKeepalivePeriod > 0 {
+				if err := tc.SetKeepAlivePeriod(s.TCPKeepalivePeriod); err != nil {
+					tc.Close() //nolint:errcheck
+					return nil, err
+				}
+			}
+			c = tc
+		} else {
+			c, err = ln.Accept()
+		}
 		if err != nil {
 			if c != nil {
 				panic("BUG: net.Listener returned non-nil conn and non-nil error")