public TcpHeader(BitArrayReader dataGram, int nReceived)
{
_dataGram = dataGram;
try
{
// The first sixteen bits contain the source port.
_sourcePort = _dataGram.ReadShort();
// The next sixteen contain the destiination port.
_destinationPort = _dataGram.ReadShort();
// Next thirty two have the sequence number.
_sequenceNumber = _dataGram.ReadInt();
// Next thirty two have the acknowledgement number.
_acknowledgementNumber = _dataGram.ReadInt();
// The next sixteen bits hold the flags and the data offset.
_headerLength = _dataGram.ReadByte(4);
_dataGram.SkipBits(3);
_nFlags = _dataGram.ReadShort(9);
// The next sixteen contain the window size.
_window = _dataGram.ReadShort();
// In the next sixteen we have the checksum.
_checksum = (short)_dataGram.ReadShort();
// The following sixteen contain the urgent pointer.
_urgentPointer = _dataGram.ReadShort();
//// The data offset indicates where the data begins, so using it we
//// calculate the header length.
//_headerLength = (byte)(_dataOffset >> 12);
_headerLength *= 4;
//// Message length = Total length of the TCP packet - Header length.
//_messageLength = (ushort)(nReceived - _headerLength);
//// Copy the TCP data into the data buffer.
//_nFlags = _dataOffset & 0x3F;
_dataGram.CurrentPositionInBytes = _headerLength;
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "Network Sniffer" + (nReceived), MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}