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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ipv6_test
import (
"fmt"
"log"
"net"
"os"
"time"
"golang.org/x/net/icmp"
"golang.org/x/net/ipv6"
)
func ExampleConn_markingTCP() {
ln, err := net.Listen("tcp", "[::]:1024")
if err != nil {
log.Fatal(err)
}
defer ln.Close()
for {
c, err := ln.Accept()
if err != nil {
log.Fatal(err)
}
go func(c net.Conn) {
defer c.Close()
if c.RemoteAddr().(*net.TCPAddr).IP.To16() != nil && c.RemoteAddr().(*net.TCPAddr).IP.To4() == nil {
p := ipv6.NewConn(c)
if err := p.SetTrafficClass(0x28); err != nil { // DSCP AF11
log.Fatal(err)
}
if err := p.SetHopLimit(128); err != nil {
log.Fatal(err)
}
}
if _, err := c.Write([]byte("HELLO-R-U-THERE-ACK")); err != nil {
log.Fatal(err)
}
}(c)
}
}
func ExamplePacketConn_servingOneShotMulticastDNS() {
c, err := net.ListenPacket("udp6", "[::]:5353") // mDNS over UDP
if err != nil {
log.Fatal(err)
}
defer c.Close()
p := ipv6.NewPacketConn(c)
en0, err := net.InterfaceByName("en0")
if err != nil {
log.Fatal(err)
}
mDNSLinkLocal := net.UDPAddr{IP: net.ParseIP("ff02::fb")}
if err := p.JoinGroup(en0, &mDNSLinkLocal); err != nil {
log.Fatal(err)
}
defer p.LeaveGroup(en0, &mDNSLinkLocal)
if err := p.SetControlMessage(ipv6.FlagDst|ipv6.FlagInterface, true); err != nil {
log.Fatal(err)
}
var wcm ipv6.ControlMessage
b := make([]byte, 1500)
for {
_, rcm, peer, err := p.ReadFrom(b)
if err != nil {
log.Fatal(err)
}
if !rcm.Dst.IsMulticast() || !rcm.Dst.Equal(mDNSLinkLocal.IP) {
continue
}
wcm.IfIndex = rcm.IfIndex
answers := []byte("FAKE-MDNS-ANSWERS") // fake mDNS answers, you need to implement this
if _, err := p.WriteTo(answers, &wcm, peer); err != nil {
log.Fatal(err)
}
}
}
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.To16() != nil && 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 AAAA record found")
}
c, err := net.ListenPacket("ip6:58", "::") // ICMP for IPv6
if err != nil {
log.Fatal(err)
}
defer c.Close()
p := ipv6.NewPacketConn(c)
if err := p.SetControlMessage(ipv6.FlagHopLimit|ipv6.FlagSrc|ipv6.FlagDst|ipv6.FlagInterface, true); err != nil {
log.Fatal(err)
}
wm := icmp.Message{
Type: ipv6.ICMPTypeEchoRequest, Code: 0,
Body: &icmp.Echo{
ID: os.Getpid() & 0xffff,
Data: []byte("HELLO-R-U-THERE"),
},
}
var f ipv6.ICMPFilter
f.SetAll(true)
f.Accept(ipv6.ICMPTypeTimeExceeded)
f.Accept(ipv6.ICMPTypeEchoReply)
if err := p.SetICMPFilter(&f); err != nil {
log.Fatal(err)
}
var wcm ipv6.ControlMessage
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)
}
// 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()
wcm.HopLimit = i
if _, err := p.WriteTo(wb, &wcm, &dst); err != nil {
log.Fatal(err)
}
if err := p.SetReadDeadline(time.Now().Add(3 * time.Second)); err != nil {
log.Fatal(err)
}
n, rcm, 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(58, 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,
// ControlMesage.Dst, icmp.Echo.ID and icmp.Echo.Seq.
switch rm.Type {
case ipv6.ICMPTypeTimeExceeded:
names, _ := net.LookupAddr(peer.String())
fmt.Printf("%d\t%v %+v %v\n\t%+v\n", i, peer, names, rtt, rcm)
case ipv6.ICMPTypeEchoReply:
names, _ := net.LookupAddr(peer.String())
fmt.Printf("%d\t%v %+v %v\n\t%+v\n", i, peer, names, rtt, rcm)
return
}
}
}
func ExamplePacketConn_advertisingOSPFHello() {
c, err := net.ListenPacket("ip6:89", "::") // OSPF for IPv6
if err != nil {
log.Fatal(err)
}
defer c.Close()
p := ipv6.NewPacketConn(c)
en0, err := net.InterfaceByName("en0")
if err != nil {
log.Fatal(err)
}
allSPFRouters := net.IPAddr{IP: net.ParseIP("ff02::5")}
if err := p.JoinGroup(en0, &allSPFRouters); err != nil {
log.Fatal(err)
}
defer p.LeaveGroup(en0, &allSPFRouters)
hello := make([]byte, 24) // fake hello data, you need to implement this
ospf := make([]byte, 16) // fake ospf header, you need to implement this
ospf[0] = 3 // version 3
ospf[1] = 1 // hello packet
ospf = append(ospf, hello...)
if err := p.SetChecksum(true, 12); err != nil {
log.Fatal(err)
}
cm := ipv6.ControlMessage{
TrafficClass: 0xc0, // DSCP CS6
HopLimit: 1,
IfIndex: en0.Index,
}
if _, err := p.WriteTo(ospf, &cm, &allSPFRouters); err != nil {
log.Fatal(err)
}
}