private void receiveCallback(Packet packet)
{
try
{
IpV4Datagram ipPacket = packet.Ethernet.IpV4;
UdpDatagram udpDatagram = ipPacket.Udp;
Datagram datagram = udpDatagram.Payload;
if (udpDatagram.SourcePort.Equals(68) & udpDatagram.DestinationPort.Equals(67))
{
DHCPv4Packet dhcpv4Packet = new DHCPv4Packet();
if (dhcpv4Packet.parsePacket(datagram.ToArray()))
{
List <DHCPv4Option> list = new DHCPv4Option().parseDhcpOptions(dhcpv4Packet.dhcpOptions);
foreach (DHCPv4Option dhcpMessageTypeOption in list)
{
if (dhcpMessageTypeOption.optionIdBytes.Equals(0x35))
{
switch (dhcpMessageTypeOption.optionValue[0])
{
//--Packet is a Discover
case 0x01:
Console.WriteLine("Service received:\t" + packet.Ethernet.Destination + "\tDISCOVER\txid: " + BitConverter.ToString(dhcpv4Packet.xid));
sendDhcpOffer(new MacAddress(inter.getMacAddress()), packet.Ethernet.Source, dhcpv4Packet.xid, dhcpv4Packet.secs);
break;
//--Packet is an Request
case 0x03:
foreach (DHCPv4Option dhcpServerIdentifierOption in list)
{
//--DHCP contains Server-Identifier-Option.
if (dhcpServerIdentifierOption.optionIdBytes.Equals(0x36))
{
//--DHCP-Server-Identifier equals IP-Address of DHCP-Server.
if (BitConverter.ToInt32(dhcpServerIdentifierOption.optionValue, 0).Equals(BitConverter.ToInt32(inter.getIPAddress().GetAddressBytes(), 0)))
{
Console.WriteLine("Service received:\t" + packet.Ethernet.Destination + "\tREQUEST\t\txid: " + BitConverter.ToString(dhcpv4Packet.xid) + "\tSID: " + BitConverter.ToString(dhcpServerIdentifierOption.optionValue, 0));
sendDhcpAck(new MacAddress(inter.getMacAddress()), packet.Ethernet.Source, dhcpv4Packet.xid, dhcpv4Packet.secs);
}
else
{
Console.WriteLine("Client preferes other DHCP-Server!");
}
}
}
break;
}
}
}
}
else
{
Console.WriteLine("The DHCP-Message could not be parsed...");
}
}
}
catch (Exception) { }
}
public Packet buildDhcpOffer(MacAddress pSourceMacAddress, MacAddress pDestinationMacAddress, byte[] pTransactionId, byte[] pSecs)
{
IPAddress newClientIPAddress = IPAddress.Parse("0.0.0.0");
bool clientFound = false;
if (clientList.Count != 0)
{
foreach (Client item in clientList)
{
if (StructuralComparisons.StructuralEqualityComparer.Equals(item.macAddress, pDestinationMacAddress))
{
newClientIPAddress = item.ipaddress;
clientFound = true;
Debug.WriteLine("Listed Client has been found with IP-Binding: " + newClientIPAddress.ToString());
}
}
}
if (!clientFound)
{
newClientIPAddress = addressPool.getFreeIPAddress();
Client client = new Client(newClientIPAddress.ToString(), newClientIPAddress, pTransactionId, pDestinationMacAddress);
clientList.Add(client);
Debug.WriteLine("Listed Client has been generated with IP-Binding: " + newClientIPAddress.ToString() + " and xid: " + BitConverter.ToString(pTransactionId) + " and MacAddress: " + pDestinationMacAddress.ToString());
}
IPAddress ipaddress = inter.getIPAddress();
DHCPv4Option dhcpMessageTypeOption = new DHCPv4Option
{
optionId = DHCPv4OptionIds.DhcpMessageType,
optionLength = 0x01,
optionValue = new byte[] { 0x02 },
};
DHCPv4Option dhcpServerIdentifierOption = new DHCPv4Option
{
optionId = DHCPv4OptionIds.ServerIdentifier,
optionLength = 0x04,
optionValue = ipaddress.GetAddressBytes(),
};
DHCPv4Packet dhcpPacket = new DHCPv4Packet
{
op = 0x02,
htype = 0x01,
hlen = 0x06,
xid = pTransactionId,
secs = pSecs,
ciaddr = new byte[] { 0x00, 0x00, 0x00, 0x00 },
yiaddr = newClientIPAddress.GetAddressBytes(),
siaddr = ipaddress.GetAddressBytes(),
chaddr = PhysicalAddress.Parse(pDestinationMacAddress.ToString().Replace(":", "-")).GetAddressBytes(),
dhcpOptions = dhcpMessageTypeOption.buildDhcpOption().Concat(dhcpServerIdentifierOption.buildDhcpOption()).ToArray(),
};
EthernetLayer ethernetLayer = new EthernetLayer
{
Source = pSourceMacAddress,
Destination = pDestinationMacAddress
};
IpV4Layer ipV4Layer = new IpV4Layer
{
Source = new IpV4Address(ipaddress.ToString()),
CurrentDestination = new IpV4Address(newClientIPAddress.ToString()),
Ttl = 128,
};
UdpLayer udpLayer = new UdpLayer
{
SourcePort = (ushort)67,
DestinationPort = (ushort)68,
};
PayloadLayer payloadLayer = new PayloadLayer
{
Data = new Datagram(dhcpPacket.buildPacket()),
};
PacketBuilder builder = new PacketBuilder(ethernetLayer, ipV4Layer, udpLayer, payloadLayer);
return(builder.Build(DateTime.Now));
}
public Packet buildDhcpAck(MacAddress pSourceMacAddress, MacAddress pDestinationMacAddress, byte[] pTransactionId, byte[] pSecs)
{
IPAddress newClientIPAddress = IPAddress.Parse("0.0.0.0");
bool clientFound = false;
if (clientList.Count != 0)
{
foreach (Client item in clientList)
{
if (StructuralComparisons.StructuralEqualityComparer.Equals(item.macAddress, pDestinationMacAddress))
{
newClientIPAddress = item.ipaddress;
clientFound = true;
Debug.WriteLine("Listed Client has been found with IP-Binding: " + newClientIPAddress.ToString());
}
}
}
if (!clientFound)
{
Debug.WriteLine("Server sends a NAK. There is no TransactionId paired to a leased IP-Address! The Server did not received a DISCOVER from the Client");
}
IPAddress ipaddress = inter.getIPAddress();
IPAddress subnetmask = inter.getNetmask();
DHCPv4Option dhcpMessageTypeOption = new DHCPv4Option
{
optionId = DHCPv4OptionIds.DhcpMessageType,
optionLength = 0x01,
optionValue = new byte[] { 0x05 },
};
DHCPv4Option dhcpServerIdentifierOption = new DHCPv4Option
{
optionId = DHCPv4OptionIds.ServerIdentifier,
optionLength = 0x04,
optionValue = ipaddress.GetAddressBytes(),
};
DHCPv4Option ipAddressLeaseTimeOption = new DHCPv4Option
{
optionId = DHCPv4OptionIds.IpAddressLeaseTime,
optionLength = 0x04,
optionValue = new byte[] { 0x00, 0x0d, 0x2f, 0x00 },
};
DHCPv4Option renewalTimeValueOption = new DHCPv4Option
{
optionId = DHCPv4OptionIds.RenewalTimeValue,
optionLength = 0x04,
optionValue = new byte[] { 0x00, 0x06, 0x97, 0x80 },
};
DHCPv4Option rebindTimeValueOption = new DHCPv4Option
{
optionId = DHCPv4OptionIds.RebindingTimeValue,
optionLength = 0x04,
optionValue = new byte[] { 0x00, 0x0b, 0x89, 0x20 },
};
DHCPv4Option subnetMaskOption = new DHCPv4Option
{
optionId = DHCPv4OptionIds.Subnetmask,
optionLength = 0x04,
optionValue = subnetmask.GetAddressBytes(),
};
DHCPv4Option routerOption = new DHCPv4Option
{
optionId = DHCPv4OptionIds.Router,
optionLength = 0x04,
optionValue = addressPool.getGatewayIpAddress().GetAddressBytes(),
};
DHCPv4Option domainNameServerOption = new DHCPv4Option
{
optionId = DHCPv4OptionIds.DomainNameServer,
optionLength = 0x04,
optionValue = ipaddress.GetAddressBytes(),
};
DHCPv4Option domainNameOption = new DHCPv4Option
{
optionId = DHCPv4OptionIds.DomainName,
optionLength = (byte)addressPool.getDomainName().Length,
optionValue = Encoding.ASCII.GetBytes(addressPool.getDomainName()),
};
DHCPv4Packet dhcpPacket = new DHCPv4Packet
{
op = 0x02,
htype = 0x01,
hlen = 0x06,
xid = pTransactionId,
secs = pSecs,
ciaddr = new byte[] { 0x00, 0x00, 0x00, 0x00 },
yiaddr = newClientIPAddress.GetAddressBytes(),
siaddr = ipaddress.GetAddressBytes(),
chaddr = PhysicalAddress.Parse(pDestinationMacAddress.ToString().Replace(":", "-")).GetAddressBytes(),
dhcpOptions = dhcpMessageTypeOption.buildDhcpOption().Concat(dhcpServerIdentifierOption.buildDhcpOption()).Concat(ipAddressLeaseTimeOption.buildDhcpOption()).Concat(renewalTimeValueOption.buildDhcpOption()).Concat(rebindTimeValueOption.buildDhcpOption()).Concat(subnetMaskOption.buildDhcpOption()).Concat(routerOption.buildDhcpOption()).Concat(domainNameServerOption.buildDhcpOption()).Concat(domainNameOption.buildDhcpOption()).ToArray(),
};
EthernetLayer ethernetLayer = new EthernetLayer
{
Source = pSourceMacAddress,
Destination = pDestinationMacAddress
};
IpV4Layer ipV4Layer = new IpV4Layer
{
Source = new IpV4Address(ipaddress.ToString()),
CurrentDestination = new IpV4Address(newClientIPAddress.ToString()),
Ttl = 128,
};
UdpLayer udpLayer = new UdpLayer
{
SourcePort = (ushort)67,
DestinationPort = (ushort)68,
};
PayloadLayer payloadLayer = new PayloadLayer
{
Data = new Datagram(dhcpPacket.buildPacket()),
};
PacketBuilder builder = new PacketBuilder(ethernetLayer, ipV4Layer, udpLayer, payloadLayer);
return(builder.Build(DateTime.Now));
}
