/// <summary>
/// This routine builds the ICMPv6 packet and payload into a byte array.
/// It also computes the IPv6 pseudo header checksum that appears in the
/// ICMPv6 packet.
/// </summary>
/// <param name="payLoad">A byte array representing the ICMPv6 payload</param>
/// <returns>A byte array of the ICMPv6 packet and payload</returns>
public override byte[] GetProtocolPacketBytes(byte[] payLoad)
{
byte[] icmpv6Packet, pseudoHeader, byteValue;
int offset = 0, payLoadLength;
// Build the ICMPv6 packet first since its required in the pseudo header calculation
icmpv6Packet = new byte[Icmpv6HeaderLength + payLoad.Length];
offset = 0;
icmpv6Packet[offset++] = icmpType;
icmpv6Packet[offset++] = icmpCode;
icmpv6Packet[offset++] = 0;
icmpv6Packet[offset++] = 0;
// Copy the payload into the build ICMPv6 packet
Array.Copy(payLoad, 0, icmpv6Packet, offset, payLoad.Length);
// Now build the pseudo header
pseudoHeader = new byte[40 + icmpv6Packet.Length];
offset = 0;
byteValue = ipv6Header.SourceAddress.GetBytes();
Array.Copy(byteValue, 0, pseudoHeader, offset, byteValue.Length);
offset += byteValue.Length;
byteValue = ipv6Header.DestinationAddress.GetBytes();
Array.Copy(byteValue, 0, pseudoHeader, offset, byteValue.Length);
offset += byteValue.Length;
// Packet total length
payLoadLength = NetworkingHelpers.HostToNetworkOrder(Icmpv6HeaderLength + payLoad.Length);
byteValue = BitConverter.GetBytes(payLoadLength);
Array.Copy(byteValue, 0, pseudoHeader, offset, byteValue.Length);
offset += byteValue.Length;
// 3 bytes of zero padding
pseudoHeader[offset++] = (byte)0;
pseudoHeader[offset++] = (byte)0;
pseudoHeader[offset++] = (byte)0;
pseudoHeader[offset++] = (byte)ipv6Header.NextHeader;
// Next is the icmpv6 header and its payload
Array.Copy(icmpv6Packet, 0, pseudoHeader, offset, icmpv6Packet.Length);
offset += icmpv6Packet.Length;
// Compute checksum on pseudo header
Checksum = ComputeChecksum(pseudoHeader);
// Go back and put the checksum value into the marshalled byte array
byteValue = BitConverter.GetBytes(icmpChecksum);
Array.Copy(byteValue, 0, icmpv6Packet, 2, byteValue.Length);
return(icmpv6Packet);
}
/// <summary>
/// This method builds the byte array representation of the UDP header as it would appear
/// on the wire. To do this it must build the IPv4 or IPv6 pseudo header in order to
/// calculate the checksum on the packet. This requires knowledge of the IPv4 or IPv6 header
/// so one of these must be set before a UDP packet can be set.
///
/// The IPv4 pseudo header consists of:
/// 4-byte source IP address
/// 4-byte destination address
/// 1-byte zero field
/// 1-byte protocol field
/// 2-byte UDP length
/// 2-byte source port
/// 2-byte destination port
/// 2-byte UDP packet length
/// 2-byte UDP checksum (zero)
/// UDP payload (padded to the next 16-bit boundary)
/// The IPv6 pseudo header consists of:
/// 16-byte source address
/// 16-byte destination address
/// 4-byte payload length
/// 3-byte zero pad
/// 1-byte protocol value
/// 2-byte source port
/// 2-byte destination port
/// 2-byte UDP length
/// 2-byte UDP checksum (zero)
/// UDP payload (padded to the next 16-bit boundary)
/// </summary>
/// <param name="payLoad">Payload that follows the UDP header</param>
/// <returns></returns>
public override byte[] GetProtocolPacketBytes(byte[] payLoad)
{
byte[] udpPacket = new byte[UdpHeaderLength + payLoad.Length], pseudoHeader = null, byteValue = null;
int offset = 0;
// Build the UDP packet first
byteValue = BitConverter.GetBytes(srcPort);
Array.Copy(byteValue, 0, udpPacket, offset, byteValue.Length);
offset += byteValue.Length;
byteValue = BitConverter.GetBytes(destPort);
Array.Copy(byteValue, 0, udpPacket, offset, byteValue.Length);
offset += byteValue.Length;
byteValue = BitConverter.GetBytes(udpLength);
Array.Copy(byteValue, 0, udpPacket, offset, byteValue.Length);
offset += byteValue.Length;
udpPacket[offset++] = 0; // Checksum is initially zero
udpPacket[offset++] = 0;
// Copy payload to end of packet
Array.Copy(payLoad, 0, udpPacket, offset, payLoad.Length);
if (ipv4PacketHeader != null)
{
pseudoHeader = new byte[UdpHeaderLength + 12 + payLoad.Length];
// Build the IPv4 pseudo header
offset = 0;
// Source address
byteValue = ipv4PacketHeader.SourceAddress.GetBytes();
Array.Copy(byteValue, 0, pseudoHeader, offset, byteValue.Length);
offset += byteValue.Length;
// Destination address
byteValue = ipv4PacketHeader.DestinationAddress.GetBytes();
Array.Copy(byteValue, 0, pseudoHeader, offset, byteValue.Length);
offset += byteValue.Length;
// 1 byte zero pad plus next header protocol value
pseudoHeader[offset++] = 0;
pseudoHeader[offset++] = ipv4PacketHeader.Protocol;
// Packet length
byteValue = BitConverter.GetBytes(udpLength);
Array.Copy(byteValue, 0, pseudoHeader, offset, byteValue.Length);
offset += byteValue.Length;
// Copy the UDP packet to the end of this
Array.Copy(udpPacket, 0, pseudoHeader, offset, udpPacket.Length);
}
else if (ipv6PacketHeader != null)
{
uint ipv6PayloadLength;
pseudoHeader = new byte[UdpHeaderLength + 40 + payLoad.Length];
// Build the IPv6 pseudo header
offset = 0;
// Source address
byteValue = ipv6PacketHeader.SourceAddress.GetBytes();
Array.Copy(byteValue, 0, pseudoHeader, offset, byteValue.Length);
offset += byteValue.Length;
// Destination address
byteValue = ipv6PacketHeader.DestinationAddress.GetBytes();
Array.Copy(byteValue, 0, pseudoHeader, offset, byteValue.Length);
offset += byteValue.Length;
ipv6PayloadLength = (uint)NetworkingHelpers.HostToNetworkOrder((int)(payLoad.Length + UdpHeaderLength));
// Packet payload: ICMPv6 headers plus payload
byteValue = BitConverter.GetBytes(ipv6PayloadLength);
Array.Copy(byteValue, 0, pseudoHeader, offset, byteValue.Length);
offset += byteValue.Length;
// 3 bytes zero pad plus next header protocol value
pseudoHeader[offset++] = 0;
pseudoHeader[offset++] = 0;
pseudoHeader[offset++] = 0;
pseudoHeader[offset++] = ipv6PacketHeader.NextHeader;
// Copy the UDP packet to the end of this
Array.Copy(udpPacket, 0, pseudoHeader, offset, udpPacket.Length);
}
if (pseudoHeader != null)
{
Checksum = ComputeChecksum(pseudoHeader);
}
// Put checksum back into packet
byteValue = BitConverter.GetBytes(udpChecksum);
Array.Copy(byteValue, 0, udpPacket, 6, byteValue.Length);
return(udpPacket);
}
