/// <summary>
/// Verifies whether the checksum for a serialised SCTP packet is valid.
/// </summary>
/// <param name="buffer">The buffer holding the serialised packet.</param>
/// <param name="posn">The start position in the buffer.</param>
/// <param name="length">The length of the packet in the buffer.</param>
/// <returns>True if the checksum was valid, false if not.</returns>
public static bool VerifyChecksum(byte[] buffer, int posn, int length)
{
uint origChecksum = NetConvert.ParseUInt32(buffer, posn + CHECKSUM_BUFFER_POSITION);
NetConvert.ToBuffer(0U, buffer, posn + CHECKSUM_BUFFER_POSITION);
uint calcChecksum = CRC32C.Calculate(buffer, posn, length);
// Put the original checksum back.
NetConvert.ToBuffer(origChecksum, buffer, posn + CHECKSUM_BUFFER_POSITION);
return(origChecksum == NetConvert.EndianFlip(calcChecksum));
}
/// <summary>
/// Serialises an SCTP packet to a byte array.
/// </summary>
/// <returns>The byte array containing the serialised SCTP packet.</returns>
public byte[] GetBytes()
{
int chunksLength = Chunks.Sum(x => x.GetChunkLength(true));
byte[] buffer = new byte[SctpHeader.SCTP_HEADER_LENGTH + chunksLength];
Header.WriteToBuffer(buffer, 0);
int writePosn = SctpHeader.SCTP_HEADER_LENGTH;
foreach (var chunk in Chunks)
{
writePosn += chunk.WriteTo(buffer, writePosn);
}
NetConvert.ToBuffer(0U, buffer, CHECKSUM_BUFFER_POSITION);
uint checksum = CRC32C.Calculate(buffer, 0, buffer.Length);
NetConvert.ToBuffer(NetConvert.EndianFlip(checksum), buffer, CHECKSUM_BUFFER_POSITION);
return(buffer);
}