/// <summary>
/// This routine creates an instance of the Ipv4Header class from a byte
/// array that is a received IGMP packet. This is useful when a packet
/// is received from the network and the header object needs to be
/// constructed from those values.
/// </summary>
/// <param name="ipv4Packet">Byte array containing the binary IPv4 header</param>
/// <param name="bytesCopied">Number of bytes used in header</param>
/// <returns>Returns the Ipv4Header object created from the byte array</returns>
public static Ipv4Header Create(byte[] ipv4Packet, ref int bytesCopied)
{
Ipv4Header ipv4Header = new Ipv4Header();
// Make sure byte array is large enough to contain an IPv4 header
if (ipv4Packet.Length < Ipv4Header.Ipv4HeaderLength)
return null;
// Decode the data in the array back into the class properties
ipv4Header.ipVersion = (byte)((ipv4Packet[0] >> 4) & 0xF);
ipv4Header.ipLength = (byte)(ipv4Packet[0] & 0xF);
ipv4Header.ipTypeOfService = ipv4Packet[1];
ipv4Header.ipTotalLength = BitConverter.ToUInt16(ipv4Packet, 2);
ipv4Header.ipId = BitConverter.ToUInt16(ipv4Packet, 4);
ipv4Header.ipOffset = BitConverter.ToUInt16(ipv4Packet, 6);
ipv4Header.ipTtl = ipv4Packet[8];
ipv4Header.ipProtocol = ipv4Packet[9];
ipv4Header.ipChecksum = BitConverter.ToUInt16(ipv4Packet, 10);
ipv4Header.ipSourceAddress = new IPAddress(BitConverter.ToUInt32(ipv4Packet, 12));
ipv4Header.ipDestinationAddress = new IPAddress(BitConverter.ToUInt32(ipv4Packet, 16));
bytesCopied = ipv4Header.Length;
return ipv4Header;
}
/// <summary>
/// Simple constructor for the UDP header.
/// </summary>
public UdpHeader()
: base()
{
srcPort = 0;
destPort = 0;
udpLength = 0;
udpChecksum = 0;
ipv6PacketHeader = null;
ipv4PacketHeader = null;
}