/// <summary>
/// Parses an SCTP chunk from a buffer.
/// </summary>
/// <param name="buffer">The buffer holding the serialised chunk.</param>
/// <param name="posn">The position to start parsing at.</param>
/// <returns>An SCTP chunk instance.</returns>
public static SctpChunk Parse(byte[] buffer, int posn)
{
if (buffer.Length < posn + SCTP_CHUNK_HEADER_LENGTH)
{
throw new ApplicationException("Buffer did not contain the minimum of bytes for an SCTP chunk.");
}
byte chunkType = buffer[posn];
if (Enum.IsDefined(typeof(SctpChunkType), chunkType))
{
switch ((SctpChunkType)chunkType)
{
case SctpChunkType.ABORT:
return(SctpAbortChunk.ParseChunk(buffer, posn, true));
case SctpChunkType.DATA:
return(SctpDataChunk.ParseChunk(buffer, posn));
case SctpChunkType.ERROR:
return(SctpErrorChunk.ParseChunk(buffer, posn, false));
case SctpChunkType.SACK:
return(SctpSackChunk.ParseChunk(buffer, posn));
case SctpChunkType.COOKIE_ACK:
case SctpChunkType.COOKIE_ECHO:
case SctpChunkType.HEARTBEAT:
case SctpChunkType.HEARTBEAT_ACK:
case SctpChunkType.SHUTDOWN_ACK:
case SctpChunkType.SHUTDOWN_COMPLETE:
return(ParseBaseChunk(buffer, posn));
case SctpChunkType.INIT:
case SctpChunkType.INIT_ACK:
return(SctpInitChunk.ParseChunk(buffer, posn));
case SctpChunkType.SHUTDOWN:
return(SctpShutdownChunk.ParseChunk(buffer, posn));
default:
logger.LogDebug($"TODO: Implement parsing logic for well known chunk type {(SctpChunkType)chunkType}.");
return(ParseBaseChunk(buffer, posn));
}
}
// Shouldn't reach this point. The SCTP packet parsing logic checks if the chunk is
// recognised before attempting to parse it.
throw new ApplicationException($"SCTP chunk type of {chunkType} was not recognised.");
}
/// <summary>
/// Sends an SCTP control packet with an abort chunk to terminate
/// the association.
/// </summary>
/// <param name="errorCause">The cause of the abort.</param>
public void Abort(ISctpErrorCause errorCause)
{
if (!_wasAborted)
{
_wasAborted = true;
bool tBit = _remoteVerificationTag != 0;
var abortChunk = new SctpAbortChunk(tBit);
abortChunk.AddErrorCause(errorCause);
SendChunk(abortChunk);
OnAborted?.Invoke(errorCause.CauseCode.ToString());
_dataSender.Close();
}
}