private static void BlockPacket(ILiveDevice device, WinpkFilterHeader header, Packet packet)
{
var ip = packet.Extract <IPv4Packet>();
var tcp = packet.Extract <TcpPacket>();
if (WebHelper.Address.Equals(ip?.DestinationAddress) &&
tcp?.DestinationPort == 80)
{
// No packet shall pass
return;
}
AllowPacket(device, header, packet);
}
private static void DirtyPacket(ILiveDevice device, WinpkFilterHeader header, Packet packet)
{
var ip = packet.Extract <IPv4Packet>();
var tcp = packet.Extract <TcpPacket>();
if (WebHelper.Address.Equals(ip?.DestinationAddress) &&
tcp?.DestinationPort == 80)
{
// Let's mess with the request a bit
var data = Encoding.UTF8.GetString(tcp.PayloadData);
data = data.Replace("HTTP", "HTML");
tcp.PayloadData = Encoding.UTF8.GetBytes(data);
ip.UpdateIPChecksum();
tcp.UpdateTcpChecksum();
}
AllowPacket(device, header, packet);
}
internal static PhysicalAddress Resolve(
ILiveDevice device,
System.Net.IPAddress destIP,
System.Net.IPAddress localIP,
PhysicalAddress localMAC,
TimeSpan timeout)
{
//Build a new ARP request packet
var request = BuildRequest(destIP, localMAC, localIP);
//create a "tcpdump" filter for allowing only arp replies to be read
String arpFilter = "arp and ether dst " + localMAC.ToString();
//set the filter
device.Filter = arpFilter;
// set a last request time that will trigger sending the
// arp request immediately
var lastRequestTime = DateTime.FromBinary(0);
var requestInterval = new TimeSpan(0, 0, 1);
PacketDotNet.ArpPacket arpPacket = null;
// attempt to resolve the address with the current timeout
var timeoutDateTime = DateTime.Now + timeout;
while (DateTime.Now < timeoutDateTime)
{
if (requestInterval < (DateTime.Now - lastRequestTime))
{
// inject the packet to the wire
device.SendPacket(request);
lastRequestTime = DateTime.Now;
}
//read the next packet from the network
var retval = device.GetNextPacket(out PacketCapture e);
if (retval != GetPacketStatus.PacketRead)
{
continue;
}
var reply = e.GetPacket();
// parse the packet
var packet = PacketDotNet.Packet.ParsePacket(reply.LinkLayerType, reply.Data);
// is this an arp packet?
arpPacket = packet.Extract <PacketDotNet.ArpPacket>();
if (arpPacket == null)
{
continue;
}
//if this is the reply we're looking for, stop
if (arpPacket.SenderProtocolAddress.Equals(destIP))
{
break;
}
}
// the timeout happened
if (DateTime.Now >= timeoutDateTime)
{
return(null);
}
else
{
//return the resolved MAC address
return(arpPacket.SenderHardwareAddress);
}
}
private static void AllowPacket(ILiveDevice device, WinpkFilterHeader header, Packet packet)
{
device.SendPacket(packet.Bytes, header);
}
