extract http.Server from http.Request and use it in http2.ServeConnOpts

Author: WeidiDeng

Diff for: http2/h2c/h2c.go

@@ -70,6 +70,15 @@ func NewHandler(h http.Handler, s *http2.Server) http.Handler {
 	}
 }
 
+// extractServer extracts existing http.Server instance from http.Request or create an empty http.Server
+func extractServer(r *http.Request) *http.Server {
+	server, ok := r.Context().Value(http.ServerContextKey).(*http.Server)
+	if ok {
+		return server
+	}
+	return new(http.Server)
+}
+
 // ServeHTTP implement the h2c support that is enabled by h2c.GetH2CHandler.
 func (s h2cHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// Handle h2c with prior knowledge (RFC 7540 Section 3.4)
@@ -87,6 +96,7 @@ func (s h2cHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		defer conn.Close()
 		s.s.ServeConn(conn, &http2.ServeConnOpts{
 			Context:          r.Context(),
+			BaseConfig:       extractServer(r),
 			Handler:          s.Handler,
 			SawClientPreface: true,
 		})
@@ -104,6 +114,7 @@ func (s h2cHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		defer conn.Close()
 		s.s.ServeConn(conn, &http2.ServeConnOpts{
 			Context:        r.Context(),
+			BaseConfig:     extractServer(r),
 			Handler:        s.Handler,
 			UpgradeRequest: r,
 			Settings:       settings,