enable TCP keep-alives

server.go

@@ -1230,15 +1230,38 @@ func (ctx *RequestCtx) TimeoutErrorWithResponse(resp *Response) {
 	ctx.timeoutResponse = respCopy
 }
 
+// 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
+}
+
+func (ln tcpKeepAliveListener) Accept() (net.Conn, error) {
+	tc, err := ln.AcceptTCP()
+	if err != nil {
+		return nil, err
+	}
+	tc.SetKeepAlive(true)
+	tc.SetKeepAlivePeriod(3 * time.Minute)
+	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
 // such as IPv6.
+//
+// Accepted connections are configured to enable TCP keep-alives.
 func (s *Server) ListenAndServe(addr string) error {
 	ln, err := net.Listen("tcp4", addr)
 	if err != nil {
 		return err
 	}
+	if tcpln, ok := ln.(*net.TCPListener); ok {
+		return s.Serve(tcpKeepAliveListener{tcpln})
+	}
 	return s.Serve(ln)
 }
 
@@ -1270,11 +1293,16 @@ func (s *Server) ListenAndServeUNIX(addr string, mode os.FileMode) error {
 //
 // If the certFile or keyFile has not been provided to the server structure,
 // the function will use the previously added TLS configuration.
+//
+// Accepted connections are configured to enable TCP keep-alives.
 func (s *Server) ListenAndServeTLS(addr, certFile, keyFile string) error {
 	ln, err := net.Listen("tcp4", addr)
 	if err != nil {
 		return err
 	}
+	if tcpln, ok := ln.(*net.TCPListener); ok {
+		return s.ServeTLS(tcpKeepAliveListener{tcpln}, certFile, keyFile)
+	}
 	return s.ServeTLS(ln, certFile, keyFile)
 }
 
@@ -1287,11 +1315,16 @@ func (s *Server) ListenAndServeTLS(addr, certFile, keyFile string) error {
 //
 // If the certFile or keyFile has not been provided the server structure,
 // the function will use previously added TLS configuration.
+//
+// Accepted connections are configured to enable TCP keep-alives.
 func (s *Server) ListenAndServeTLSEmbed(addr string, certData, keyData []byte) error {
 	ln, err := net.Listen("tcp4", addr)
 	if err != nil {
 		return err
 	}
+	if tcpln, ok := ln.(*net.TCPListener); ok {
+		return s.ServeTLSEmbed(tcpKeepAliveListener{tcpln}, certData, keyData)
+	}
 	return s.ServeTLSEmbed(ln, certData, keyData)
 }