// We received a ping, send a pong in reply
private async Task SendPongReplyAsync(CancellationToken cancellationToken)
{
await _writeLock.WaitAsync(cancellationToken);
try
{
if (State != WebSocketState.Open)
{
// Output closed, discard the pong.
return;
}
ArraySegment <byte> dataSegment = new ArraySegment <byte>(_receiveBuffer, _receiveBufferOffset, (int)_frameBytesRemaining);
if (_unmaskInput)
{
// _frameInProgress.Masked == _unmaskInput already verified
Utilities.MaskInPlace(_frameInProgress.MaskKey, dataSegment);
}
int mask = GetNextMask();
FrameHeader header = new FrameHeader(true, Constants.OpCodes.PongFrame, _maskOutput, mask, _frameBytesRemaining);
if (_maskOutput)
{
Utilities.MaskInPlace(mask, dataSegment);
}
ArraySegment <byte> headerSegment = header.Buffer;
await _stream.WriteAsync(headerSegment.Array, headerSegment.Offset, headerSegment.Count, cancellationToken);
await _stream.WriteAsync(dataSegment.Array, dataSegment.Offset, dataSegment.Count, cancellationToken);
}
finally
{
_writeLock.Release();
}
}
private async Task ReadNextFrameAsync(CancellationToken cancellationToken)
{
await EnsureDataAvailableOrReadAsync(2, cancellationToken);
int frameHeaderSize = FrameHeader.CalculateFrameHeaderSize(_receiveBuffer[_receiveBufferOffset + 1]);
await EnsureDataAvailableOrReadAsync(frameHeaderSize, cancellationToken);
_frameInProgress = new FrameHeader(new ArraySegment <byte>(_receiveBuffer, _receiveBufferOffset, frameHeaderSize));
_receiveBufferOffset += frameHeaderSize;
_receiveBufferBytes -= frameHeaderSize;
_frameBytesRemaining = _frameInProgress.DataLength;
if (_frameInProgress.AreReservedSet())
{
await SendErrorAbortAndThrow(WebSocketCloseStatus.ProtocolError, "Unexpected reserved bits set", cancellationToken);
}
if (_unmaskInput != _frameInProgress.Masked)
{
await SendErrorAbortAndThrow(WebSocketCloseStatus.ProtocolError, "Incorrect masking", cancellationToken);
}
if (!ValidateOpCode(_frameInProgress.OpCode))
{
await SendErrorAbortAndThrow(WebSocketCloseStatus.ProtocolError, "Invalid opcode: " + _frameInProgress.OpCode, cancellationToken);
}
if (_frameInProgress.IsControlFrame)
{
if (_frameBytesRemaining > 125)
{
await SendErrorAbortAndThrow(WebSocketCloseStatus.ProtocolError, "Invalid control frame size", cancellationToken);
}
if (!_frameInProgress.Fin)
{
await SendErrorAbortAndThrow(WebSocketCloseStatus.ProtocolError, "Fragmented control frame", cancellationToken);
}
if (_frameInProgress.OpCode == Constants.OpCodes.PingFrame || _frameInProgress.OpCode == Constants.OpCodes.PongFrame)
{
// Drain it, should be less than 125 bytes
await EnsureDataAvailableOrReadAsync((int)_frameBytesRemaining, cancellationToken);
if (_frameInProgress.OpCode == Constants.OpCodes.PingFrame)
{
await SendPongReplyAsync(cancellationToken);
}
_receiveBufferOffset += (int)_frameBytesRemaining;
_receiveBufferBytes -= (int)_frameBytesRemaining;
_frameBytesRemaining = 0;
_frameInProgress = null;
}
}
else if (_firstDataOpCode.HasValue && _frameInProgress.OpCode != Constants.OpCodes.ContinuationFrame)
{
// A data frame is already in progress, but this new frame is not a continuation frame.
await SendErrorAbortAndThrow(WebSocketCloseStatus.ProtocolError, "Expected a continuation frame: " + _frameInProgress.OpCode, cancellationToken);
}
}
public async override Task <WebSocketReceiveResult> ReceiveAsync(ArraySegment <byte> buffer, CancellationToken cancellationToken)
{
ThrowIfDisposed();
ThrowIfInputClosed();
ValidateSegment(buffer);
// TODO: InvalidOperationException if any receives are currently in progress.
// No active frame. Loop because we may be discarding ping/pong frames.
while (_frameInProgress == null)
{
await ReadNextFrameAsync(cancellationToken);
}
int opCode = _frameInProgress.OpCode;
if (opCode == Constants.OpCodes.CloseFrame)
{
return(await ProcessCloseFrameAsync(cancellationToken));
}
// Handle fragmentation, remember the first frame type
if (opCode == Constants.OpCodes.ContinuationFrame)
{
if (!_firstDataOpCode.HasValue)
{
await SendErrorAbortAndThrow(WebSocketCloseStatus.ProtocolError, "Invalid continuation frame", cancellationToken);
}
opCode = _firstDataOpCode.Value;
}
else
{
_firstDataOpCode = opCode;
}
// Make sure there's at least some data in the buffer
int bytesToBuffer = (int)Math.Min((long)_receiveBuffer.Length, _frameBytesRemaining);
await EnsureDataAvailableOrReadAsync(bytesToBuffer, cancellationToken);
// Copy buffered data to the users buffer
int bytesToRead = (int)Math.Min((long)buffer.Count, _frameBytesRemaining);
int bytesToCopy = Math.Min(bytesToRead, _receiveBufferBytes);
Array.Copy(_receiveBuffer, _receiveBufferOffset, buffer.Array, buffer.Offset, bytesToCopy);
if (_unmaskInput)
{
// _frameInProgress.Masked == _unmaskInput already verified
Utilities.MaskInPlace(_frameInProgress.MaskKey, ref _dataUnmaskOffset, new ArraySegment <byte>(buffer.Array, buffer.Offset, bytesToCopy));
}
WebSocketReceiveResult result;
WebSocketMessageType messageType = Utilities.GetMessageType(opCode);
if (messageType == WebSocketMessageType.Text &&
!Utilities.TryValidateUtf8(new ArraySegment <byte>(buffer.Array, buffer.Offset, bytesToCopy), _frameInProgress.Fin, _incomingUtf8MessageState))
{
await SendErrorAbortAndThrow(WebSocketCloseStatus.InvalidPayloadData, "Invalid UTF-8", cancellationToken);
}
if (bytesToCopy == _frameBytesRemaining)
{
result = new WebSocketReceiveResult(bytesToCopy, messageType, _frameInProgress.Fin);
if (_frameInProgress.Fin)
{
_firstDataOpCode = null;
}
_frameInProgress = null;
_dataUnmaskOffset = 0;
}
else
{
result = new WebSocketReceiveResult(bytesToCopy, messageType, false);
}
_frameBytesRemaining -= bytesToCopy;
_receiveBufferBytes -= bytesToCopy;
_receiveBufferOffset += bytesToCopy;
return(result);
}