正确的 WebSocket 连接关闭

huangapple
go评论120阅读模式
英文:

correct websocket connection closure

问题

我写了一个连接关闭函数。它发送一个关闭帧，并期望得到相同的响应。

  1. func TryCloseNormally(wsConn *websocket.Conn) error {
  2.     closeNormalClosure := websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")
  3.     defer wsConn.Close()
  4.     if err := wsConn.WriteControl(websocket.CloseMessage, closeNormalClosure, time.Now().Add(time.Second)); err != nil {
  5.         return err
  6.     }
  7.     if err := wsConn.SetReadDeadline(time.Now().Add(time.Second)); err != nil {
  8.         return err
  9.     }
  10.     _, _, err := wsConn.ReadMessage()
  11.     if websocket.IsCloseError(err, websocket.CloseNormalClosure) {
  12.         return nil
  13.     } else {
  14.         return errors.New("Websocket doesn't send a close frame in response")
  15.     }
  16. }

我为这个函数编写了一个测试。

  1. func TestTryCloseNormally(t *testing.T) {
  2.     done := make(chan struct{})
  3.     exit := make(chan struct{})
  4.     ctx := context.Background()
  6.     ln, err := net.Listen("tcp", "localhost:")
  7.     require.Nil(t, err)
  8.     handler := HandlerFunc(func(conn *websocket.Conn) {
  9.         for {
  10.             _, _, err := conn.ReadMessage()
  11.             if err != nil {
  12.                 require.True(t, websocket.IsCloseError(err, websocket.CloseNormalClosure), err.Error())
  13.                 return
  14.             }
  15.         }
  16.     })
  18.     s, err := makeServer(ctx, handler)
  19.     require.Nil(t, err)
  20.     go func() {
  21.         require.Nil(t, s.Run(ctx, exit, ln))
  22.         close(done)
  23.     }()
  25.     wsConn, _, err := websocket.DefaultDialer.Dial(addr+strconv.Itoa(ln.Addr().(*net.TCPAddr).Port), nil) //nolint:bodyclose
  26.     require.Nil(t, err)
  27.     require.Nil(t, wsConn.WriteMessage(websocket.BinaryMessage, []byte{'o', 'k'}))
  28.     require.Nil(t, TryCloseNormally(wsConn))
  29.     close(exit)
  31.     <-done
  32. }

令我惊讶的是，它正常工作。ReadMessage() 读取了关闭帧。但在测试中，我没有写任何内容。
1）这是在 gorilla/websocket 层面上发生的吗？
2）我是否正确编写了这个函数？也许读取响应帧也是在 gorilla 层面上发生的。

英文:

I wrote a connection closure function. It sends a closing frame and expects the same in response.

  1. func TryCloseNormally(wsConn *websocket.Conn) error {
  2. 	closeNormalClosure := websocket.FormatCloseMessage(websocket.CloseNormalClosure, &quot;&quot;)
  3. 	defer wsConn.Close()
  4. 	if err := wsConn.WriteControl(websocket.CloseMessage, closeNormalClosure, time.Now().Add(time.Second)); err != nil {
  5. 		return err
  6. 	}
  7. 	if err := wsConn.SetReadDeadline(time.Now().Add(time.Second)); err != nil {
  8. 		return err
  9. 	}
  10. 	_, _, err := wsConn.ReadMessage()
  11. 	if websocket.IsCloseError(err, websocket.CloseNormalClosure) {
  12. 		return nil
  13. 	} else {
  14. 		return errors.New(&quot;Websocket doesn&#39;t send a close frame in response&quot;)
  15. 	}
  16. }

I wrote a test for this function.

  1. func TestTryCloseNormally(t *testing.T) {
  2. 	done := make(chan struct{})
  3. 	exit := make(chan struct{})
  4. 	ctx := context.Background()
  6. 	ln, err := net.Listen(&quot;tcp&quot;, &quot;localhost:&quot;)
  7. 	require.Nil(t, err)
  8. 	handler := HandlerFunc(func(conn *websocket.Conn) {
  9. 		for {
  10. 			_, _, err := conn.ReadMessage()
  11. 			if err != nil {
  12. 				require.True(t, websocket.IsCloseError(err, websocket.CloseNormalClosure), err.Error())
  13. 				return
  14. 			}
  15. 		}
  16. 	})
  18. 	s, err := makeServer(ctx, handler)
  19. 	require.Nil(t, err)
  20. 	go func() {
  21. 		require.Nil(t, s.Run(ctx, exit, ln))
  22. 		close(done)
  23. 	}()
  25. 	wsConn, _, err := websocket.DefaultDialer.Dial(addr+strconv.Itoa(ln.Addr().(*net.TCPAddr).Port), nil) //nolint:bodyclose
  26. 	require.Nil(t, err)
  27. 	require.Nil(t, wsConn.WriteMessage(websocket.BinaryMessage, []byte{&#39;o&#39;, &#39;k&#39;}))
  28. 	require.Nil(t, TryCloseNormally(wsConn))
  29. 	close(exit)
  31. 	&lt;-done
  32. }

To my surprise, it works correctly. Readmessage() reads the closing frame. But in the test, I don't write anything.

  1. Is this happening at the gorilla/websocket level?
  2. Did I write the function correctly? Maybe reading the response frame also happens at the gorilla level.

答案1

得分: 2

这个函数大部分是正确的。

Websocket端点会在端点自己发送关闭消息之前，回显关闭消息。有关更多详细信息，请参阅Websocket RFC中的Closing Handshake。

在正常关闭的情况下，应用程序应该在发送关闭消息后期望接收到关闭消息。

为了处理对等方在发送关闭消息之前发送数据消息的情况，可以读取并丢弃数据消息，直到返回错误为止。

  1. func TryCloseNormally(wsConn *websocket.Conn) error {
  2.     defer wsConn.Close()
  3.     closeNormalClosure := websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")
  4.     if err := wsConn.WriteControl(websocket.CloseMessage, closeNormalClosure, time.Now().Add(time.Second)); err != nil {
  5.         return err
  6.     }
  7.     if err := wsConn.SetReadDeadline(time.Now().Add(time.Second)); err != nil {
  8.         return err
  9.     }
  10.     for {
  11.         _, _, err := wsConn.ReadMessage()
  12.         if websocket.IsCloseError(err, websocket.CloseNormalClosure) {
  13.             return nil
  14.         }
  15.         if err != nil {
  16.             return err
  17.         }
  18.     }
  19. }

希望对你有帮助！

英文:

The function is mostly correct.

Websocket endpoints echo close messages unless the endpoint has already send a close message on its own. See Closing Handshake in the Websocket RFC for more details.

In the normal close scenario, an application should expect to receive a close message after sending a close message.

To handle the case where the peer sent a data message before the sending the close message, read and discard data messages until an error is returned.

  1. func TryCloseNormally(wsConn *websocket.Conn) error {
  2. 	defer wsConn.Close()
  3. 	closeNormalClosure := websocket.FormatCloseMessage(websocket.CloseNormalClosure, &quot;&quot;)
  4. 	if err := wsConn.WriteControl(websocket.CloseMessage, closeNormalClosure, time.Now().Add(time.Second)); err != nil {
  5. 		return err
  6. 	}
  7. 	if err := wsConn.SetReadDeadline(time.Now().Add(time.Second)); err != nil {
  8. 		return err
  9. 	}
  10. 	for {
  11. 		_, _, err := wsConn.ReadMessage()
  12. 		if websocket.IsCloseError(err, websocket.CloseNormalClosure) {
  13. 			return nil
  14. 		}
  15. 		if err != nil {
  16. 			return err
  17. 		}
  18. 	}
  19. }

huangapple
  • 本文由 发表于 2021年10月6日 00:58:40
  • 转载请务必保留本文链接：https://go.coder-hub.com/69454526.html
  • go
  • gorilla
  • websocket
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确定