make h2quic.Server.ListenAndServe error if it was closed before

h2quic/server.go

@@ -50,6 +50,7 @@ type Server struct {
 
 	listenerMutex sync.Mutex
 	listener      quic.Listener
+	closed        bool
 
 	supportedVersionsAsString string
 }
@@ -88,6 +89,10 @@ func (s *Server) serveImpl(tlsConfig *tls.Config, conn net.PacketConn) error {
 		return errors.New("use of h2quic.Server without http.Server")
 	}
 	s.listenerMutex.Lock()
+	if s.closed {
+		s.listenerMutex.Unlock()
+		return errors.New("Server is already closed")
+	}
 	if s.listener != nil {
 		s.listenerMutex.Unlock()
 		return errors.New("ListenAndServe may only be called once")
@@ -242,6 +247,7 @@ func (s *Server) handleRequest(session streamCreator, headerStream quic.Stream,
 func (s *Server) Close() error {
 	s.listenerMutex.Lock()
 	defer s.listenerMutex.Unlock()
+	s.closed = true
 	if s.listener != nil {
 		err := s.listener.Close()
 		s.listener = nil

h2quic/server_test.go

@@ -410,6 +410,13 @@ var _ = Describe("H2 server", func() {
 		Expect(err).NotTo(HaveOccurred())
 	})
 
+	It("errors when ListenAndServer is called after Close", func() {
+		serv := &Server{Server: &http.Server{}}
+		Expect(serv.Close()).To(Succeed())
+		err := serv.ListenAndServe()
+		Expect(err).To(MatchError("Server is already closed"))
+	})
+
 	Context("ListenAndServe", func() {
 		BeforeEach(func() {
 			s.Server.Addr = "localhost:0"