/// <summary>
/// Sets the data section of this udp packet
/// </summary>
/// <param name="data">the data bytes</param>
public void SetData(byte[] data)
{
byte[] headers = ArrayHelper.copy(_bytes, 0, UDPFields_Fields.UDP_HEADER_LEN + IpHeaderLength + EthernetHeaderLength);
byte[] newBytes = ArrayHelper.join(headers, data);
this._bytes = newBytes;
UDPLength = _bytes.Length - IpHeaderLength - EthernetHeaderLength;
//update ip total length length
IPTotalLength = IpHeaderLength + UDPFields_Fields.UDP_HEADER_LEN + data.Length;
//update also offset and pcap header
OnOffsetChanged();
}
/*
* taken from TCP/IP Illustrated Vol. 2(1995) by Gary R. Wright and W.
* Richard Stevens. Page 236
*/
/// <summary> Computes the IP checksum, optionally updating the IP checksum header.
///
/// </summary>
/// <param name="update">Specifies whether or not to update the IP 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 IP checksum.
/// </returns>
public int ComputeIPChecksum(bool update)
{
//copy the ip header
byte[] ip = ArrayHelper.copy(_bytes, _ethOffset, IpHeaderLength);
//reset the checksum field (checksum is calculated when this field is zeroed)
ArrayHelper.insertLong(ip, 0, IPFields_Fields.IP_CSUM_POS, 2);
//compute the one's complement sum of the ip header
int cs = _OnesCompSum(ip, 0, ip.Length);
if (update)
{
IPChecksum = cs;
}
return(cs);
}