private async Task <StreamReadInfo> GetStreamReadInfo(WebSocketFrameHeader header, CancellationToken cancellationToken)
{
cancellationToken.ThrowIfCancellationRequested();
/* Extended Payload Length */
var size = header.PayloadLength < 126 ? 0 : header.PayloadLength == 126 ? 2 : 8;
var extPayloadLen = size > 0 ? await _innerStream.ReadBytes(size).ConfigureAwait(false) : new byte[0];
if (size > 0 && extPayloadLen.Length != size)
{
throw new WebSocketException("The 'Extended Payload Length' of a frame cannot be read from the data source.");
}
/* Masking Key */
var masked = header.Mask == Mask.Mask;
var maskingKey = masked ? await _innerStream.ReadBytes(4).ConfigureAwait(false) : new byte[0];
if (masked && maskingKey.Length != 4)
{
throw new WebSocketException("The 'Masking Key' of a frame cannot be read from the data source.");
}
/* Payload Data */
var len = header.PayloadLength < 126
? header.PayloadLength
: header.PayloadLength == 126
? extPayloadLen.ToUInt16(ByteOrder.Big)
: extPayloadLen.ToUInt64(ByteOrder.Big);
return(new StreamReadInfo(header.Fin == Fin.Final, len, maskingKey));
}
private async Task <WebSocketFrameHeader> ReadHeader(CancellationToken cancellationToken)
{
cancellationToken.ThrowIfCancellationRequested();
byte[] header;
try
{
header = await _innerStream.ReadBytes(2).ConfigureAwait(false);
}
catch (IOException)
{
return(null);
}
if (header.Length == 0)
{
return(null);
}
if (header.Length != 2)
{
throw new WebSocketException("The header part of a frame cannot be read from the data source.");
}
var frameHeader = new WebSocketFrameHeader(header);
var validation = WebSocketFrameHeader.Validate(frameHeader);
if (validation != null)
{
throw new WebSocketException(CloseStatusCode.ProtocolError, validation);
}
return(frameHeader);
}
private WebSocketMessage CreateMessage(WebSocketFrameHeader header, StreamReadInfo readInfo, SemaphoreSlim waitHandle)
{
switch (header.Opcode)
{
case Opcode.Cont:
throw new WebSocketException(CloseStatusCode.InconsistentData, "Did not expect continuation frame.");
default:
case Opcode.Close:
case Opcode.Text:
case Opcode.Binary:
return(new FragmentedMessage(header.Opcode, _innerStream, readInfo, GetStreamReadInfo, waitHandle, _fragmentLength));
}
}
public static string Validate(WebSocketFrameHeader header)
{
// Check if valid header
var err = IsControl(header.Opcode) && header.PayloadLength > 125
? "A control frame has a payload data which is greater than the allowable max size."
: IsControl(header.Opcode) && header.Fin == Fin.More
? "A control frame is fragmented."
: !IsData(header.Opcode) && header.Rsv1 == Rsv.On
? "A non data frame (" + header.Opcode + ") is compressed."
: null;
if (!string.IsNullOrWhiteSpace(err))
{
Trace.TraceError(err);
}
return(err);
}