func (ipad Net) ResolveIPAddr(p string, a string) (*net.IPAddr, error) {
var i net.IPAddr
i.Zone = "france"
i.IP = net.ParseIP("localhost")
ptr := &i
return ptr, nil
}
func ExamplePacketConn_tracingIPPacketRoute() {
// Tracing an IP packet route to www.google.com.
const host = "www.google.com"
ips, err := net.LookupIP(host)
if err != nil {
log.Fatal(err)
}
var dst net.IPAddr
for _, ip := range ips {
if ip.To4() != nil {
dst.IP = ip
fmt.Printf("using %v for tracing an IP packet route to %s\n", dst.IP, host)
break
}
}
if dst.IP == nil {
log.Fatal("no A record found")
}
c, err := net.ListenPacket(fmt.Sprintf("ip4:%d", iana.ProtocolICMP), "0.0.0.0") // ICMP for IPv4
if err != nil {
log.Fatal(err)
}
defer c.Close()
p := ipv4.NewPacketConn(c)
if err := p.SetControlMessage(ipv4.FlagTTL|ipv4.FlagSrc|ipv4.FlagDst|ipv4.FlagInterface, true); err != nil {
log.Fatal(err)
}
wm := icmp.Message{
Type: ipv4.ICMPTypeEcho, Code: 0,
Body: &icmp.Echo{
ID: os.Getpid() & 0xffff,
Data: []byte("HELLO-R-U-THERE"),
},
}
rb := make([]byte, 1500)
for i := 1; i <= 64; i++ { // up to 64 hops
wm.Body.(*icmp.Echo).Seq = i
wb, err := wm.Marshal(nil)
if err != nil {
log.Fatal(err)
}
if err := p.SetTTL(i); err != nil {
log.Fatal(err)
}
// In the real world usually there are several
// multiple traffic-engineered paths for each hop.
// You may need to probe a few times to each hop.
begin := time.Now()
if _, err := p.WriteTo(wb, nil, &dst); err != nil {
log.Fatal(err)
}
if err := p.SetReadDeadline(time.Now().Add(3 * time.Second)); err != nil {
log.Fatal(err)
}
n, cm, peer, err := p.ReadFrom(rb)
if err != nil {
if err, ok := err.(net.Error); ok && err.Timeout() {
fmt.Printf("%v\t*\n", i)
continue
}
log.Fatal(err)
}
rm, err := icmp.ParseMessage(iana.ProtocolICMP, rb[:n])
if err != nil {
log.Fatal(err)
}
rtt := time.Since(begin)
// In the real world you need to determine whether the
// received message is yours using ControlMessage.Src,
// ControlMessage.Dst, icmp.Echo.ID and icmp.Echo.Seq.
switch rm.Type {
case ipv4.ICMPTypeTimeExceeded:
names, _ := net.LookupAddr(peer.String())
fmt.Printf("%d\t%v %+v %v\n\t%+v\n", i, peer, names, rtt, cm)
case ipv4.ICMPTypeEchoReply:
names, _ := net.LookupAddr(peer.String())
fmt.Printf("%d\t%v %+v %v\n\t%+v\n", i, peer, names, rtt, cm)
return
default:
log.Printf("unknown ICMP message: %+v\n", rm)
}
}
}
