x/net/ipv6: add package example
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/176960043
diff --git a/ipv6/example_test.go b/ipv6/example_test.go
new file mode 100644
index 0000000..96cbec9
--- /dev/null
+++ b/ipv6/example_test.go
@@ -0,0 +1,215 @@
+// 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/internal/iana"
+ "golang.org/x/net/internal/icmp"
+ "golang.org/x/net/ipv6"
+)
+
+func ExampleConn_markingTCP() {
+ ln, err := net.Listen("tcp6", "[::]: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()
+ p := ipv6.NewConn(c)
+ if err := p.SetTrafficClass(iana.DiffServAF11); err != nil {
+ 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(fmt.Sprintf("ip6:%d", iana.ProtocolIPv6ICMP), "::") // 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.Set(ipv6.ICMPTypeTimeExceeded, false)
+ f.Set(ipv6.ICMPTypeEchoReply, false)
+ 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(iana.ProtocolIPv6ICMP, 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(fmt.Sprintf("ip6:%d", iana.ProtocolOSPFIGP), "::") // 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: iana.DiffServCS6,
+ HopLimit: 1,
+ IfIndex: en0.Index,
+ }
+ if _, err := p.WriteTo(ospf, &cm, &allSPFRouters); err != nil {
+ log.Fatal(err)
+ }
+}
