public void FilterMethods()
{
using var device = TestHelper.GetPcapDevice();
device.Open();
var filterExpression = "arp";
var mask = (uint)0;
var result = PcapDevice.CompileFilter(device.PcapHandle, filterExpression, mask, out IntPtr bpfProgram, out string errorString);
Assert.IsTrue(result);
var arp = new ARP(device);
var destinationIP = new System.Net.IPAddress(new byte[] { 8, 8, 8, 8 });
// Note: We don't care about the success or failure here
arp.Resolve(destinationIP);
// retrieve some packets, looking for the arp
var header = IntPtr.Zero;
var data = IntPtr.Zero;
var foundBpfMatch = false;
var packetsToTry = 10;
var sw = System.Diagnostics.Stopwatch.StartNew();
while (packetsToTry > 0)
{
if (sw.ElapsedMilliseconds > 2000)
{
break;
}
var retval = device.GetNextPacketPointers(ref header, ref data);
if (retval == 1)
{
packetsToTry--;
Assert.AreNotEqual(IntPtr.Zero, header);
Assert.AreNotEqual(IntPtr.Zero, data);
// and test it against the bpf filter to confirm an exception is not thrown
Assert.DoesNotThrow(() =>
{
// we expect a match as we are sending an arp packet
if (PcapDevice.RunBpfProgram(bpfProgram, header, data))
{
foundBpfMatch = true;
}
}
);
}
}
Assert.IsTrue(foundBpfMatch);
PcapDevice.FreeBpfProgram(bpfProgram);
}
