c# - 来自 Xamarin Android 应用程序的 TCP 数据已损坏

Question

我有一个 Xamarin Android 应用程序，它从 Android 4.4 (KitKat) 设备(x86 硬件)捕获 h264 视频帧并通过 TCP 将它们发送到 Windows 10 客户端(通过 WiFi)。我正在使用 protobuf.net 将帧与 SerializeWithLengthPrefix (Fixed32) 打包在一起。这在大多数情况下都运行良好，但随机(在 20 秒到 10 分钟之间)接收端的数据会损坏。可以看到我也把数据保存到设备中进行调试。使用客户端应用程序读取此数据不会产生任何错误(它没有损坏)。我不知道问题出在哪里。这似乎是 Xamarin 的 TCP 客户端的平台错误，但我很难相信我会是唯一遇到此问题的人。注意:TCP 通信在它自己的线程中工作。

   private static void ProcessFrameQueue(TcpClient client)
        {
            //debug log for comparing TCP socket sent data with client recieved
            _tempDumpFile = StreamControl.GetOutputTempFilePath(DateTime.Now.Ticks.ToString() + "-probuf-dump.bin");

            var sentFrameCount = 0;
            try
            {

                while (client.Client.IsConnected())
                {
                    var data = _packetQueue.Take();
                    try
                    {
                        using (var stream = new MemoryStream())
                        {

                            Serializer.SerializeWithLengthPrefix(stream, data, PrefixStyle.Fixed32);
                            var protoBufData = stream.ToArray();
                            client.Client.Send(protoBufData);

                            //for debugging -- save the TCP data for comparison to what is recieved
                            //todo: delete as this is debuggng
                            using (var filestream = new FileStream(_tempDumpFile, FileMode.Append))
                            {
                                filestream.Write(protoBufData, 0, protoBufData.Length);
                                filestream.Flush(true);
                            }
                        }
                        sentFrameCount++;

                    }
                    catch (Exception ex)
                    {
                        //log error

                    }
                } //end while

            }
            catch (Exception ex)
            {
               //log error
            }
        }

这是我为调试而编写的一个简单客户端(我正在手动计算数据包大小以确保它不是 protobuf.net 中的错误——这不是 protobuf.net 问题)。最终 size 数据包将包含导致溢出的错误数据。

  var client = new TcpClient("x.x.x.x", 19901);
        client.ReceiveTimeout = 100000000;
        byte[] bytes = new byte[client.ReceiveBufferSize];
        var netStream = client.GetStream();

        var sizezReadBtyes = 0;



        var sizeBytes = new byte[4];
        var packetCount = 0;
        while (true)
        {

            //reads until it gets 4 bytes to calculate the packet size
            var sizeOffset = 0;
            var sizeLength = 4;
            while ((sizezReadBtyes = netStream.Read(sizeBytes, sizeOffset, sizeLength)) > 0)
            {
                sizeOffset += sizezReadBtyes;
                sizeLength -= sizezReadBtyes;
            }

            //read the remaining data...
            var offset = 0;
            var packetBytes = 0;
            int packetlength = BitConverter.ToInt32(sizeBytes, 0);
            var buffer = new byte[packetlength];


            while (packetlength > 0 && (packetBytes = netStream.Read(buffer, offset, packetlength)) > 0)
            {
                offset += packetBytes;
                packetlength -= packetBytes;
            }
            using (var ms = new MemoryStream(buffer))
            {
                var obj = ProtoBuf.Serializer.Deserialize<NetworkMediaPacket>(ms);
                Console.WriteLine($"packet found {packetCount++} {obj.Data.Length}");
            }

            if (packetlength > 0) throw new EndOfStreamException();

        }

Answer 1

我能够通过删除我的阻塞队列 (_packetQueue) 来修复。我刚刚在 TCPClient NetStream 上使用了 writeasync。在我看来，这就像 Xamarin/Mono/.net 代码中的错误。