private void AuthenticateHeader(IByteBuffer input)
{
input.ReadBytes(_macBytes);
bool isValidMac = _authenticator.CheckMac(_macBytes, true);
if (!isValidMac)
{
throw new CorruptedFrameException("Sender delivered a frame with an invalid header MAC");
}
}
protected override void Decode(IChannelHandlerContext context, IByteBuffer input, List <object> output)
{
if (_state == FrameDecoderState.WaitingForHeader)
{
if (_logger.IsTraceEnabled)
{
_logger.Trace($"Decoding frame header {input.ReadableBytes}");
}
if (input.ReadableBytes == 0)
{
_logger.Warn($"{context.Channel.RemoteAddress} sent an empty frame, disconnecting");
context.CloseAsync();
return;
}
if (input.ReadableBytes >= 32)
{
input.ReadBytes(_headerBuffer);
if (_logger.IsTraceEnabled)
{
_logger.Trace($"Decoding encrypted frame header {new Hex(_headerBuffer)}");
}
_frameMacProcessor.CheckMac(_headerBuffer, 0, 16, true);
_frameCipher.Decrypt(_headerBuffer, 0, 16, _headerBuffer, 0);
_totalBodySize = _headerBuffer[0] & 0xFF;
_totalBodySize = (_totalBodySize << 8) + (_headerBuffer[1] & 0xFF);
_totalBodySize = (_totalBodySize << 8) + (_headerBuffer[2] & 0xFF);
_state = FrameDecoderState.WaitingForPayload;
int paddingSize = 16 - _totalBodySize % 16;
if (paddingSize == 16)
{
paddingSize = 0;
}
if (_logger.IsTraceEnabled)
{
_logger.Trace($"Expecting a message {_totalBodySize} + {paddingSize} + 16");
}
}
else
{
if (_logger.IsTraceEnabled)
{
_logger.Trace("Waiting for full 32 bytes of the header");
}
return;
}
}
if (_state == FrameDecoderState.WaitingForPayload)
{
if (_logger.IsTraceEnabled)
{
_logger.Trace($"Decoding payload {input.ReadableBytes}");
}
int paddingSize = 16 - _totalBodySize % 16;
if (paddingSize == 16)
{
paddingSize = 0;
}
int expectedSize = _totalBodySize + paddingSize + MacSize;
byte[] buffer;
if (input.ReadableBytes >= expectedSize)
{
buffer = new byte[expectedSize];
input.ReadBytes(buffer);
}
else
{
return;
}
if (_logger.IsTraceEnabled)
{
_logger.Trace($"Decoding encrypted payload {new Hex(buffer)}");
}
int frameSize = buffer.Length - MacSize;
_frameMacProcessor.CheckMac(buffer, 0, frameSize, false);
_frameCipher.Decrypt(buffer, 0, frameSize, buffer, 0);
output.Add(Bytes.Concat(_headerBuffer, buffer));
if (_logger.IsTraceEnabled)
{
_logger.Trace($"Decrypted message {new Hex((byte[])output.Last())}");
}
_state = FrameDecoderState.WaitingForHeader;
}
}