public int ComputeTransportLayerChecksum(int checksumOffset, bool update, bool pseudoIPHeader)
{
// copy the tcp section with data
byte[] dataToChecksum = IPData;
// reset the checksum field (checksum is calculated when this field is
// zeroed)
ArrayHelper.insertLong(dataToChecksum, 0, checksumOffset, 2);
if (pseudoIPHeader)
{
dataToChecksum = AttachPseudoIPHeader(dataToChecksum);
}
// compute the one's complement sum of the tcp header
int cs = ChecksumUtils.OnesComplementSum(dataToChecksum);
if (update)
{
SetTransportLayerChecksum(cs, checksumOffset);
}
return(cs);
}
/// <summary> Computes the UDP checksum, optionally updating the UDP checksum header.
///
/// </summary>
/// <param name="update">Specifies whether or not to update the UDP checksum header
/// after computing the checksum. A value of true indicates the
/// header should be updated, a value of false indicates it should
/// not be updated.
/// </param>
/// <returns> The computed UDP checksum.
/// </returns>
public int ComputeUDPChecksum(bool update)
{
if (IPVersion != IPVersions.IPv4)
{
throw new System.NotImplementedException("IPVersion of " + IPVersion + " is unrecognized");
}
// copy the udp section with data
byte[] udp = IPData;
// reset the checksum field (checksum is calculated when this field is
// zeroed)
ArrayHelper.insertLong(udp, 0, UDPFields_Fields.UDP_CSUM_POS, UDPFields_Fields.UDP_CSUM_LEN);
//pseudo ip header should be attached to the udp+data
udp = AttachPseudoIPHeader(udp);
// compute the one's complement sum of the udp header
int cs = ChecksumUtils.OnesComplementSum(udp);
if (update)
{
UDPChecksum = cs;
}
return(cs);
}
/// <summary> Sets the urgent pointer.
///
/// </summary>
/// <param name="pointer">The urgent pointer value.
/// </param>
public void setUrgentPointer(int pointer)
{
ArrayHelper.insertLong(Bytes, pointer, _ipOffset + TCPFields_Fields.TCP_URG_POS, TCPFields_Fields.TCP_URG_LEN);
_urgentPointerSet = false;
}
/// <summary> Sets the IP header checksum.</summary>
protected internal virtual void SetChecksum(int cs, int checkSumOffset)
{
ArrayHelper.insertLong(Bytes, cs, checkSumOffset, 2);
}