--- /dev/null
+// Copyright 2012 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 ipv4_test
+
+import (
+ "fmt"
+ "log"
+ "net"
+ "os"
+ "runtime"
+ "time"
+
+ "golang.org/x/net/icmp"
+ "golang.org/x/net/ipv4"
+)
+
+func ExampleConn_markingTCP() {
+ ln, err := net.Listen("tcp", "0.0.0.0:1024")
+ 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.To4() != nil {
+ p := ipv4.NewConn(c)
+ if err := p.SetTOS(0x28); err != nil { // DSCP AF11
+ log.Fatal(err)
+ }
+ if err := p.SetTTL(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("udp4", "0.0.0.0:5353") // mDNS over UDP
+ if err != nil {
+ log.Fatal(err)
+ }
+ defer c.Close()
+ p := ipv4.NewPacketConn(c)
+
+ en0, err := net.InterfaceByName("en0")
+ if err != nil {
+ log.Fatal(err)
+ }
+ mDNSLinkLocal := net.UDPAddr{IP: net.IPv4(224, 0, 0, 251)}
+ if err := p.JoinGroup(en0, &mDNSLinkLocal); err != nil {
+ log.Fatal(err)
+ }
+ defer p.LeaveGroup(en0, &mDNSLinkLocal)
+ if err := p.SetControlMessage(ipv4.FlagDst, true); err != nil {
+ log.Fatal(err)
+ }
+
+ b := make([]byte, 1500)
+ for {
+ _, cm, peer, err := p.ReadFrom(b)
+ if err != nil {
+ log.Fatal(err)
+ }
+ if !cm.Dst.IsMulticast() || !cm.Dst.Equal(mDNSLinkLocal.IP) {
+ continue
+ }
+ answers := []byte("FAKE-MDNS-ANSWERS") // fake mDNS answers, you need to implement this
+ if _, err := p.WriteTo(answers, nil, 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.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("ip4:1", "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(1, 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)
+ }
+ }
+}
+
+func ExampleRawConn_advertisingOSPFHello() {
+ c, err := net.ListenPacket("ip4:89", "0.0.0.0") // OSPF for IPv4
+ if err != nil {
+ log.Fatal(err)
+ }
+ defer c.Close()
+ r, err := ipv4.NewRawConn(c)
+ if err != nil {
+ log.Fatal(err)
+ }
+
+ en0, err := net.InterfaceByName("en0")
+ if err != nil {
+ log.Fatal(err)
+ }
+ allSPFRouters := net.IPAddr{IP: net.IPv4(224, 0, 0, 5)}
+ if err := r.JoinGroup(en0, &allSPFRouters); err != nil {
+ log.Fatal(err)
+ }
+ defer r.LeaveGroup(en0, &allSPFRouters)
+
+ hello := make([]byte, 24) // fake hello data, you need to implement this
+ ospf := make([]byte, 24) // fake ospf header, you need to implement this
+ ospf[0] = 2 // version 2
+ ospf[1] = 1 // hello packet
+ ospf = append(ospf, hello...)
+ iph := &ipv4.Header{
+ Version: ipv4.Version,
+ Len: ipv4.HeaderLen,
+ TOS: 0xc0, // DSCP CS6
+ TotalLen: ipv4.HeaderLen + len(ospf),
+ TTL: 1,
+ Protocol: 89,
+ Dst: allSPFRouters.IP.To4(),
+ }
+
+ var cm *ipv4.ControlMessage
+ switch runtime.GOOS {
+ case "darwin", "linux":
+ cm = &ipv4.ControlMessage{IfIndex: en0.Index}
+ default:
+ if err := r.SetMulticastInterface(en0); err != nil {
+ log.Fatal(err)
+ }
+ }
+ if err := r.WriteTo(iph, ospf, cm); err != nil {
+ log.Fatal(err)
+ }
+}
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