/// <summary>
/// Add IPV4 header to packet
/// </summary>
/// <param name="packet">Packet structure</param>
/// <param name="sourceIP">Source IP</param>
/// <param name="destIP">Destination IP</param>
/// <param name="protocol">Protocol</param>
/// <returns></returns>
private static unsafe IPV4Header *addHeader(NetPacketDesc *packet, byte[] sourceIP, byte[] destIP, byte protocol)
{
packet->start -= (short)sizeof(IPV4Header);
IPV4Header *header = (IPV4Header *)(packet->buffer + packet->start);
header->Version = (4 << 4) | 5;
header->ServicesField = 0;
header->totalLength = Byte.ReverseBytes((ushort)(packet->end - packet->start));
header->ID = Byte.ReverseBytes(0xa836); // TODO: FIX THIS!
header->FragmentOffset = 0;
header->TTL = 250;
header->Protocol = protocol;
// The checksum calculation needs to be done with header checksum filled in as zero
// then it is filled in later
header->HeaderChecksum = 0;
Memory.Memcpy(header->Source, Util.ObjectToVoidPtr(sourceIP), 4);
Memory.Memcpy(header->Destination, Util.ObjectToVoidPtr(destIP), 4);
header->HeaderChecksum = (NetworkTools.Checksum(packet->buffer + packet->start, sizeof(IPV4Header)));
return(header);
}
