/// <summary>
/// Read DHCP packet to object
/// </summary>
public static DHCPPacketBase Read(NetworkBinaryReader reader)
{
reader.BaseStream.Seek(0, SeekOrigin.Begin);
if (reader.BaseStream.Length < PacketMinimumLength)
{
throw new DHCPException(string.Format("Packet too small: {0} bytes", reader.BaseStream.Length));
}
if (reader.BaseStream.Length > PacketMaxLength)
{
throw new DHCPException(string.Format("Packet too large: {0} bytes", reader.BaseStream.Length));
}
DHCPPacketBase p;
using (reader)
{
Debug.WriteLine("");
Debug.WriteLine("--- Reading DHCP packet");
Debug.WriteLine("");
Debug.WriteLine(string.Format("Reading op code at offset {0:D4}", reader.BaseStream.Position));
EOpCode PacketType = (EOpCode)(byte)reader.ReadByte(); // 1
switch (PacketType)
{
case EOpCode.BootReply:
p = new DHCPPacketBootReply();
break;
case EOpCode.BootRequest:
p = new DHCPPacketBootRequest();
break;
default:
throw new DHCPException("Unknown OpCode.");
}
Debug.WriteLine(string.Format("Reading hardware address type at offset {0:D4}", reader.BaseStream.Position));
p.HardwareAddressType = (EHardwareType)(byte)reader.ReadByte(); // 1 (2)
Debug.WriteLine(string.Format("Reading hardware address length at offset {0:D4}", reader.BaseStream.Position));
byte _hwaddrlen = (byte)reader.ReadByte(); // 1 (3)
if (_hwaddrlen > 16)
{
throw new DHCPException(String.Format("Malformed packet. Hardware address length was {0}.", _hwaddrlen));
}
Debug.WriteLine(string.Format("Reading hops at offset {0:D4}", reader.BaseStream.Position));
p.Hops = (byte)reader.ReadByte(); // 1 (4)
Debug.WriteLine(string.Format("Reading transaction ID at offset {0:D4}", reader.BaseStream.Position));
p.TransactionID = reader.ReadUInt32(); // 4 (8)
Debug.WriteLine(string.Format("Reading seconds at offset {0:D4}", reader.BaseStream.Position));
p.Seconds = reader.ReadUInt16(); // 2 (10)
Debug.WriteLine(string.Format("Reading flags at offset {0:D4}", reader.BaseStream.Position));
p.Flags = reader.ReadUInt16(); // 2 (12)
Debug.WriteLine(string.Format("Reading IPv4 addresses at offset {0:D4}", reader.BaseStream.Position));
p.ClientAddress = new IPv4Address(reader.ReadBytes(4)); // 4 (16)
p.YourAddress = new IPv4Address(reader.ReadBytes(4)); // 4 (20)
p.ServerAddress = new IPv4Address(reader.ReadBytes(4)); // 4 (24)
p.RelayAgentAddress = new IPv4Address(reader.ReadBytes(4)); // 4 (28)
// 16 (44)
byte[] _clienthwaddr = { };
if (_hwaddrlen > 0)
{
Debug.WriteLine(string.Format("Reading hardware address length at offset {0:D4}", reader.BaseStream.Position));
_clienthwaddr = reader.ReadBytes(_hwaddrlen);
}
// Discard rest
reader.BaseStream.Seek(44, SeekOrigin.Begin);
Debug.WriteLine(string.Format("Reading server host name at offset {0:D4}", reader.BaseStream.Position));
p.ServerHostName = reader.ReadBytes(64); // 64 (128)
//reader.BaseStream.Seek(108, SeekOrigin.Begin);
Debug.WriteLine(string.Format("Reading file name at offset {0:D4}", reader.BaseStream.Position));
p.File = reader.ReadBytes(128); // 128 (236)
if (p.HardwareAddressType == EHardwareType.Ethernet && _hwaddrlen == 6)
{
byte[] macaddr = new byte[6];
Array.Copy(_clienthwaddr, 0, macaddr, 0, 6);
p.ClientHardwareAddress = new HardwareAddress(new MacAddress(macaddr));
}
else
{
p.ClientHardwareAddress = new HardwareAddress(_clienthwaddr);
}
if (reader.BaseStream.Position != 236)
{
throw new DHCPException(
string.Format("Packet position should be at 236 bytes but it is {0}.", reader.BaseStream.Position));
}
bool validCookie = true;
Debug.WriteLine(string.Format("Reading magic cookie at offset {0:D4}", reader.BaseStream.Position));
if (reader.ReadByte() != 99)
{
validCookie = false;
}
if (reader.ReadByte() != 130)
{
validCookie = false;
}
if (reader.ReadByte() != 83)
{
validCookie = false;
}
if (reader.ReadByte() != 99)
{
validCookie = false;
}
if (!validCookie)
{
throw new DHCPException(String.Format("Malformed packet: Magic cookie not found."));
}
if (reader.BaseStream.Position != 240)
{
throw new DHCPException(
string.Format("Packet position should be at 240 bytes but it is {0}.", reader.BaseStream.Position));
}
// Options
p.Options = ReadOptions(reader);
}
return(p);
}
/// <summary>
/// Read DHCP packet options to objects
/// </summary>
public static List <Option> ReadOptions(NetworkBinaryReader reader)
{
List <Option> options = new List <Option>();
using (reader)
{
Debug.WriteLine("");
Debug.WriteLine("--- Reading DHCP options");
Debug.WriteLine("");
try
{
// Format:
// Code | Length | Data
// byte | byte | n bytes (determined by length)
// Except metadata code (0 and 255) is only 1 byte
do
{
// Get code
byte code = reader.ReadByte();
Option o = OptionFactory.GetOption(code);
if (code != o.Code)
{
throw new OptionException(string.Format("Invalid option code: '{0}' class: '{1}'.", code, o.GetType()));
}
if (!(o is AOptionMetaData))
{
// Get length of data
byte len = reader.ReadByte();
// Buffer for data
byte[] data = reader.ReadBytes(len);
if (data.Length != len)
{
throw new IndexOutOfRangeException();
}
try
{
o.ReadRaw(data);
}
catch (OptionException e)
{
Debug.WriteLine(e);
if (ThrowExceptionOnParse)
{
throw;
}
}
}
options.Add(o);
}while (reader.BaseStream.Position < reader.BaseStream.Length);
}
catch (EndOfStreamException e)
{
if (ThrowExceptionOnParse)
{
string err = string.Format(
"Error reading: position: {0} len: {1}. Options read: {2}",
reader.BaseStream.Position,
reader.BaseStream.Length,
options.Count
);
throw new OptionException(err, e);
}
}
}
return(options);
}
/// <summary>
/// Read DHCP packet options to objects
/// </summary>
public static List <Option> ReadOptions(byte[] raw)
{
NetworkBinaryReader reader = new NetworkBinaryReader(new MemoryStream(raw, 0, raw.Length));
return(ReadOptions(reader));
}
/// <summary>
/// Read DHCP packet to object
/// </summary>
public static DHCPPacketBase Read(byte[] raw)
{
NetworkBinaryReader reader = new NetworkBinaryReader(new MemoryStream(raw, 0, raw.Length));
return(Read(reader));
}
