// 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 handlePacket(p gopacket.Packet) {
ap := AP{}
// extract beacon
// extract Ssid
for _, l := range p.Layers() {
switch l.LayerType() {
case layers.LayerTypeDot11MgmtBeacon:
beacon, ok := p.Layer(layers.LayerTypeDot11MgmtBeacon).(*layers.Dot11MgmtBeacon)
if !ok {
log.Println("Could not marshal layer thing")
continue
}
pack := gopacket.NewPacket(beacon.LayerContents(), layers.LayerTypeDot11MgmtBeacon, gopacket.Default)
for _, subpack := range pack.Layers() {
info, ok := subpack.(*layers.Dot11InformationElement)
if !ok {
continue
}
if info.ID == layers.Dot11InformationElementIDSSID {
ap.Ssid = fmt.Sprintf("%s", info.Info)
break
}
}
case layers.LayerTypeDot11:
base, ok := p.Layer(layers.LayerTypeDot11).(*layers.Dot11)
if !ok {
continue
}
ap.Bssid = base.Address2
continue
case layers.LayerTypeRadioTap:
radio, ok := p.Layer(layers.LayerTypeRadioTap).(*layers.RadioTap)
if !ok {
continue
}
ap.Channel = radio.ChannelFrequency
continue
}
}
APList[ap.Ssid] = ap
}
//Returns both the source & destination IP.
func getSrcDstIP(packet gopacket.Packet) (net.IP, net.IP) {
ipLayer := packet.Layer(layers.LayerTypeIPv4)
// Get IP data from this layer
ip, _ := ipLayer.(*layers.IPv4)
return ip.SrcIP, ip.DstIP
}