Panic if trying to close or start and already closed socket

httpx/websocket.go

@@ -99,6 +99,10 @@ func (s *socket) OnMessage(fn func([]byte)) { s.onMessage = fn }
 func (s *socket) OnClose(fn func(int))      { s.onClose = fn }
 
 func (s *socket) Start() {
+	if s.closingWithCode != 0 {
+		panic("can't start socket which is closed or closing")
+	}
+
 	s.conn.SetReadDeadline(time.Now().Add(maxReadWait))
 	s.conn.SetPongHandler(s.pong)
 
@@ -116,6 +120,10 @@ func (s *socket) Send(msg []byte) {
 }
 
 func (s *socket) Close(code int) {
+	if s.closingWithCode != 0 {
+		panic("can't close socket which is already closed or closing")
+	}
+
 	s.closingWithCode = code
 
 	s.outbox <- message{type_: websocket.CloseMessage, data: websocket.FormatCloseMessage(code, "")}

httpx/websocket_test.go

@@ -105,6 +105,17 @@ func TestSocketMessages(t *testing.T) {
 
 	assert.Equal(t, 1001, serverCloseCode)
 	assert.Equal(t, 1001, connCloseCode)
+
+	// check we can no longer send to the socket or close it again, or restart it
+	assert.Panics(t, func() {
+		sock.Send([]byte("x"))
+	})
+	assert.Panics(t, func() {
+		sock.Close(1000)
+	})
+	assert.Panics(t, func() {
+		sock.Start()
+	})
 }
 
 func TestSocketClientCloseWithMessage(t *testing.T) {