public void Start(NetworkStream stream, TcpReceiveBuffer receiveBuffer)
{
var state = new TcpStreamMessageReadingState
{
Stream = stream,
ReceiveBuffer = receiveBuffer,
AcceptReadBuffer = new byte[this._maxMessageSize * this._maxMessageQueueSize],
AcceptReadBufferSize = 0,
MessageSize = 0,
ReadCallback = AcceptRead,
Logger = this._logger,
};
stream.BeginRead(
state.AcceptReadBuffer,
0,
state.AcceptReadBuffer.Length,
state.ReadCallback,
state);
}
private static void AcceptRead(IAsyncResult ar)
{
TcpStreamMessageReadingState state = (TcpStreamMessageReadingState)ar.AsyncState;
NetworkStream stream = state.Stream;
if (stream == null || !stream.CanRead)
{
return;
}
int bytesRead;
try
{
bytesRead = stream.EndRead(ar);
}
catch
{
// Assume the socket has closed.
return;
}
if (bytesRead == 0)
{
// Socket has closed.
stream.Close(); // Close the stream for immediate disconnection.
return;
}
state.AcceptReadBufferSize += bytesRead;
// We need at least the frame header data to do anything.
while (state.AcceptReadBufferSize >= FrameHeaderSizeByteCount)
{
if (state.MessageSize == 0)
{
// Starting new message, get message size in bytes.
// First two bytes of the buffer is always the message size
state.MessageSize = BitConverter.ToUInt16(state.AcceptReadBuffer, 0);
state.TransactionId = BitConverter.ToUInt16(state.AcceptReadBuffer, 2);
}
if (FrameHeaderSizeByteCount + state.MessageSize <= state.AcceptReadBufferSize)
{
// Complete message data available.
if (state.ReceiveBuffer.GetWriteData(out byte[] data, out int offset, out int size))
{
Debug.Assert(state.MessageSize <= size);
// Copy data minus frame preamble
Array.Copy(state.AcceptReadBuffer, FrameHeaderSizeByteCount, data, offset, state.MessageSize);
state.ReceiveBuffer.NextWrite(state.MessageSize, state.Stream, state.TransactionId);
}
else
{
state.Logger.Error($"Out of receive buffer space: capacity={state.ReceiveBuffer.PacketCapacity}");
}
// Shift accept read buffer to the next frame, if any.
for (int i = FrameHeaderSizeByteCount + state.MessageSize, j = 0; i < state.AcceptReadBufferSize; i++, j++)
{
state.AcceptReadBuffer[j] = state.AcceptReadBuffer[i];
}
state.AcceptReadBufferSize -= state.MessageSize + FrameHeaderSizeByteCount;
state.MessageSize = 0;
}
else
{
// More message bytes needed to stream.
break;
}
}
if (!stream.CanRead)
{
return;
}
try
{
// Begin waiting for more stream data.
_ = stream.BeginRead(
state.AcceptReadBuffer,
state.AcceptReadBufferSize,
state.AcceptReadBuffer.Length - state.AcceptReadBufferSize,
state.ReadCallback,
state);
}
catch
{
// Assume the socket has closed.
}
}
