internal void CreateOptionElement(DhcpOptionType optionType, byte[] dataToAdd, ref byte[] source)
{
try
{
var newOption = new byte[dataToAdd.Length + 2];
//add the code, and data length
newOption[0] = (byte)optionType;
newOption[1] = (byte)dataToAdd.Length;
//add the code to put in
Array.Copy(dataToAdd, 0, newOption, 2, dataToAdd.Length);
//copy the data to the out array
if (source == null)
{
Array.Resize(ref source, newOption.Length);
}
else
{
Array.Resize(ref source, source.Length + newOption.Length);
}
Array.Copy(newOption, 0, source, source.Length - newOption.Length, newOption.Length);
}
catch (Exception e)
{
throw new Exception($"{GetType().FullName}.CreateOptionElement:{e.Message}");
}
}
public DhcpOption CreateFromRaw(DhcpOptionType type, byte[] rawData)
{
switch (type)
{
case DhcpOptionType.SubnetMask:
return(DhcpSubnetMaskOption.CreateFromRaw(rawData));
case DhcpOptionType.Router:
return(DhcpRouterOption.CreateFromRaw(rawData));
case DhcpOptionType.DomainNameServer:
return(DhcpDomainNameServerOption.CreateFromRaw(rawData));
case DhcpOptionType.DomainName:
return(DhcpDomainNameOption.CreateFromRaw(rawData));
case DhcpOptionType.ServerIdentifier:
return(DhcpServerIdentifierOption.CreateFromRaw(rawData));
case DhcpOptionType.ClientIdentifier:
return(DhcpClientIdentifier.CreateFromRaw(rawData));
default:
return(null);
}
}
public static DhcpPacket CreateFromRaw(byte[] rawPacket)
{
DhcpPacket packet = new DhcpPacket();
using (var reader = new BinaryReader(new MemoryStream(rawPacket)))
{
packet.MessageType = (DhcpMessageType)reader.ReadByte();
HardwareAddressType hardwareAddressType = (HardwareAddressType)reader.ReadByte();
byte hardwareAddressLength = reader.ReadByte();
packet.Hops = reader.ReadByte();
packet.TransactionId = (uint)IPAddress.NetworkToHostOrder(reader.ReadInt32());
packet.SecondsElapsed = (ushort)IPAddress.NetworkToHostOrder(reader.ReadInt16());
packet.Flags = (ushort)IPAddress.NetworkToHostOrder(reader.ReadInt16());
packet.ClientAddress = new IPAddress(reader.ReadBytes(4));
packet.YourClientAddress = new IPAddress(reader.ReadBytes(4));
packet.NextServerAddress = new IPAddress(reader.ReadBytes(4));
packet.RelayAgentAddress = new IPAddress(reader.ReadBytes(4));
packet.HardwareAddress = new HardwareAddress(hardwareAddressType,
reader.ReadBytes(hardwareAddressLength));
reader.ReadBytes(16 - hardwareAddressLength); // padding
packet.ServerName = Encoding.ASCII.GetString(reader.ReadBytes(64));
packet.BootFileName = Encoding.ASCII.GetString(reader.ReadBytes(128));
int packetMagicCookie = IPAddress.NetworkToHostOrder(reader.ReadInt32());
if (packetMagicCookie != MagicCookie)
{
throw new InvalidDataException("Magic cookie not found!");
}
byte messageType = reader.ReadByte();
if (messageType != 53)
{
throw new InvalidDataException("Options should start with Message type!");
}
reader.ReadByte(); // length
packet.MessageType = (DhcpMessageType)reader.ReadByte();
var optionFactory = new DhcpOptionFactory();
byte optionType = reader.ReadByte();
while (optionType != 255)
{
DhcpOptionType type = (DhcpOptionType)optionType;
byte length = reader.ReadByte();
byte[] optionData = reader.ReadBytes(length);
DhcpOption option = optionFactory.CreateFromRaw(type, optionData);
if (option != null)
{
packet.Options.Add(option);
}
else
{
Console.WriteLine($"WARN: Unsupported option type: {type}");
}
optionType = reader.ReadByte();
}
}
return(packet);
}
internal byte[] GetOptionData(DhcpOptionType optionType)
{
var code = (byte)optionType;
try
{
//loop through look for the bit that states that the identifier is there
for (int i = 0; i < options.Length; i++)
{
if (options[i] == (byte)DhcpOptionType.End)
{
break;
}
//at the start we have the code + length
//i has the code, i+1 = length of data, i+1+n = data skip
if (options[i] == code)
{
var len = options[i + 1];
var data = new byte[len];
Array.Copy(options, i + 2, data, 0, len);
return(data);
}
else
{
// jump to next option message
i += 1 + options[i + 1];
}
}
}
catch (Exception e)
{
throw new Exception($"{GetType().FullName}.GetOptionData:{e.Message}");
}
return(null);
}
