// readARP watches a handle for incoming ARP responses we might care about, and prints them.
//
// readARP loops until 'stop' is closed.
func readARP(handle *pcap.Handle, iface *net.Interface, stop chan struct{}) {
src := gopacket.NewPacketSource(handle, layers.LayerTypeEthernet)
in := src.Packets()
for {
var packet gopacket.Packet
select {
case <-stop:
return
case packet = <-in:
arpLayer := packet.Layer(layers.LayerTypeARP)
if arpLayer == nil {
continue
}
arp := arpLayer.(*layers.ARP)
if arp.Operation != layers.ARPReply || bytes.Equal([]byte(iface.HardwareAddr), arp.SourceHwAddress) {
// This is a packet I sent.
continue
}
// Note: we might get some packets here that aren't responses to ones we've sent,
// if for example someone else sends US an ARP request. Doesn't much matter, though...
// all information is good information :)
log.Printf("IP %v is at %v", net.IP(arp.SourceProtAddress), net.HardwareAddr(arp.SourceHwAddress))
}
}
}
func checkLayers(p gopacket.Packet, want []gopacket.LayerType, t *testing.T) {
layers := p.Layers()
t.Log("Checking packet layers, want", want)
for _, l := range layers {
t.Logf(" Got layer %v, %d bytes, payload of %d bytes", l.LayerType(),
len(l.LayerContents()), len(l.LayerPayload()))
}
t.Log(p)
if len(layers) != len(want) {
t.Errorf(" Number of layers mismatch: got %d want %d", len(layers),
len(want))
return
}
for i, l := range layers {
if l.LayerType() != want[i] {
t.Errorf(" Layer %d mismatch: got %v want %v", i, l.LayerType(),
want[i])
}
}
}
