private static uint ReadLength(byte byte2, Stream stream)
{
const byte payloadLenFlag = 0x7F;
var lenght = (uint)(byte2 & payloadLenFlag);
const uint maxLen = 2147483648;
if (lenght > maxLen)
{
throw new ArgumentOutOfRangeException($"Payload length out of range. Min 0 max 2GB. Actual {lenght:#,##0} bytes.");
}
if (lenght == 126)
{
var lenBuffer = BinaryReaderWriter.ReadExactly(2, stream);
lenght = BitConverter.ToUInt16(lenBuffer, 0);
}
else if (lenght == 127)
{
var lenBuffer = BinaryReaderWriter.ReadExactly(8, stream);
lenght = (uint)BitConverter.ToUInt64(lenBuffer, 0);
}
return(lenght);
}
public WebSocketFrame Read(NetworkStream stream)
{
var byte1 = (byte)stream.ReadByte();
if (!stream.DataAvailable && byte1 == 0xFF)
{
return(new WebSocketFrame(true, WebSocketOpCode.ConnectionClose, new byte[0], false));
}
const byte finBitFlag = 0x80;
const byte opCodeFlag = 0x0F;
var isFinBitSet = (byte1 & finBitFlag) == finBitFlag;
var opCode = (WebSocketOpCode)(byte1 & opCodeFlag);
var byte2 = (byte)stream.ReadByte();
const byte maskFlag = 0x80;
var isMaskBitSet = (byte2 & maskFlag) == maskFlag;
var len = ReadLength(byte2, stream);
byte[] decodedPayload;
if (isMaskBitSet)
{
const int maskKeyLen = 4;
var maskKey = BinaryReaderWriter.ReadExactly(maskKeyLen, stream);
var encodedPayload = BinaryReaderWriter.ReadExactly((int)len, stream);
decodedPayload = new byte[len];
for (var i = 0; i < encodedPayload.Length; i++)
{
decodedPayload[i] = (byte)(encodedPayload[i] ^ maskKey[i % maskKeyLen]);
}
}
else
{
decodedPayload = BinaryReaderWriter.ReadExactly((int)len, stream);
}
var frame = new WebSocketFrame(isFinBitSet, opCode, decodedPayload, true);
return(frame);
}
