websocket的ReceiveAsync方法不等待整个消息

Question

我通过websocket接收JSON.至少:我是部分的.使用在线websocket服务,我收到完整的JSON响应(忽略所有HTML标记).当我查看我在控制台中收到的JSON时,我可以看到HTML标记(在调试期间使用HTML查看器查看它删除了HTML)但它突然结束(不完整的数据).

我的缓冲区有足够的空间,我正在使用async-await(假设)在继续之前等待整个响应进来.

private async Task Receive()
{
  var buffer = new byte[4096 * 20];

  while (_socket.State == WebSocketState.Open)
  {
      var response = await _socket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);

      if (response.MessageType == WebSocketMessageType.Close)
      {
          await
              _socket.CloseAsync(WebSocketCloseStatus.NormalClosure, "Close response received",
                  CancellationToken.None);
      }
      else
      {
          var result = Encoding.UTF8.GetString(buffer);
          var a = buffer[1000];
          var b = buffer[10000];
          var c = buffer[50000];
          var d = buffer[81000];
          Console.WriteLine(result);
          var responseObject = JsonConvert.DeserializeObject<Response>(result, _requestParameters.ResponseDataType);

          OnSocketReceive.Invoke(this, new SocketEventArgs {Response = responseObject });
          buffer = new byte[4096 * 20];
      }
  }
}   

注意事项:缓冲区非常大b,c并且d永远不会被填充.我还应该注意,这只发生在1-questions-newest-tag-java请求中,155-questions-active完全正常.

在做了一些挖掘之后,我发现response.CloseStatus并且response.CloseStatusDescription总是null,response.Count总是1396(复制粘贴Word中的结果确实显示总有1396个字符)并且response.EndOfMessage是false.

通过挖掘一些源代码,我发现,DefaultReceiveBufferSize是16 * 1024(足够大),并且WebSocketGetDefaultKeepAliveInterval()是指外部执行(但调试器显示00:00:30).

这不是超时问题,因为调试器在联机服务收到响应的同一时刻停止.

当套接字尚未收到所有数据时,为什么我的方法继续执行？

Answer 1

只是为了完成@Noseratio响应,代码将是这样的:

ArraySegment<Byte> buffer = new ArraySegment<byte>(new Byte[8192]);

WebSocketReceiveResult result= null;

using (var ms = new MemoryStream())
{
     do
     {
         result = await socket.ReceiveAsync(buffer, CancellationToken.None);
         ms.Write(buffer.Array, buffer.Offset, result.Count);
     }
     while (!result.EndOfMessage);

     ms.Seek(0, SeekOrigin.Begin);

     if (result.MessageType == WebSocketMessageType.Text)
     {
          using (var reader = new StreamReader(ms, Encoding.UTF8))
          {
               // do stuff
          }
     }
}

干杯.

Answer 2

我可能错了,但我不认为你总是应该立即收到完整的WebSocket信息.服务器可以被发送以块的消息(即会对应于主叫SendAsync用endOfMessage: false).

所以,不要await _socket.ReceiveAsync()在一个循环和积累所接收到的数据块,直到WebSocketReceiveResult.EndOfMessage为true或错误发生.

另外,你可能应该使用WebSocket.CreateClientBuffer而不是new ArraySegment<byte>(buffer).

Answer 3

// Read the bytes from the web socket and accumulate all into a list.
var buffer = new ArraySegment<byte>(new byte[1024]);
WebSocketReceiveResult result = null;
var allBytes = new List<byte>();

do
{
    result = await webSocket.ReceiveAsync(buffer, CancellationToken.None);
    for (int i = 0; i < result.Count; i++)
    {
        allBytes.Add(buffer.Array[i]);
    }
}
while (!result.EndOfMessage);

// Optional step to convert to a string (UTF-8 encoding).
var text = Encoding.UTF8.GetString(allBytes.ToArray(), 0, allBytes.Count);

Answer 4

根据Noseratio的回答，我实现了一个临时缓冲区，该缓冲区将构造整个消息的数据。

var temporaryBuffer = new byte[BufferSize];
var buffer = new byte[BufferSize * 20];
int offset = 0;
WebSocketReceiveResult response;

while (true)
{
    response = await _socket.ReceiveAsync(
                         new ArraySegment<byte>(temporaryBuffer), 
                         CancellationToken.None);
    temporaryBuffer.CopyTo(buffer, offset);
    offset += response.Count;
    temporaryBuffer = new byte[BufferSize];
    if (response.EndOfMessage)
    {
        break;
    }
}

此处全面实施