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Commit 7339ca67 authored by Mikio Hara's avatar Mikio Hara
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x/net/ipv4: update package example 

LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/178800043
parent fb6231e1
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Showing with 118 additions and 180 deletions
ipv4/example_test.go
View file @ 7339ca67
......@@ -5,19 +5,25 @@
package ipv4_test
import (
"fmt"
"log"
"net"
"os"
"runtime"
"time"
"golang.org/x/net/internal/iana"
"golang.org/x/net/internal/icmp"
"golang.org/x/net/ipv4"
)
func ExampleUnicastTCPListener() {
func ExampleConn_markingTCP() {
ln, err := net.Listen("tcp4", "0.0.0.0:1024")
if err != nil {
log.Fatal(err)
}
defer ln.Close()
for {
c, err := ln.Accept()
if err != nil {
......@@ -25,261 +31,193 @@ func ExampleUnicastTCPListener() {
}
go func(c net.Conn) {
defer c.Close()
err := ipv4.NewConn(c).SetTOS(iana.DiffServAF11)
if err != nil {
p := ipv4.NewConn(c)
if err := p.SetTOS(iana.DiffServAF11); err != nil {
log.Fatal(err)
}
if err := p.SetTTL(128); err != nil {
log.Fatal(err)
}
_, err = c.Write([]byte("HELLO-R-U-THERE-ACK"))
if err != nil {
if _, err := c.Write([]byte("HELLO-R-U-THERE-ACK")); err != nil {
log.Fatal(err)
}
}(c)
}
}
func ExampleMulticastUDPListener() {
en0, err := net.InterfaceByName("en0")
if err != nil {
log.Fatal(err)
}
en1, err := net.InterfaceByIndex(911)
if err != nil {
log.Fatal(err)
}
group := net.IPv4(224, 0, 0, 250)
c, err := net.ListenPacket("udp4", "0.0.0.0:1024")
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)
err = p.JoinGroup(en0, &net.UDPAddr{IP: group})
en0, err := net.InterfaceByName("en0")
if err != nil {
log.Fatal(err)
}
err = p.JoinGroup(en1, &net.UDPAddr{IP: group})
if err != nil {
mDNSLinkLocal := net.UDPAddr{IP: net.IPv4(224, 0, 0, 251)}
if err := p.JoinGroup(en0, &mDNSLinkLocal); err != nil {
log.Fatal(err)
}
err = p.SetControlMessage(ipv4.FlagDst, true)
if err != nil {
defer p.LeaveGroup(en0, &mDNSLinkLocal)
if err := p.SetControlMessage(ipv4.FlagDst, true); err != nil {
log.Fatal(err)
}
b := make([]byte, 1500)
for {
n, cm, src, err := p.ReadFrom(b)
_, cm, peer, err := p.ReadFrom(b)
if err != nil {
log.Fatal(err)
}
if cm.Dst.IsMulticast() {
if cm.Dst.Equal(group) {
// joined group, do something
} else {
// unknown group, discard
continue
}
if !cm.Dst.IsMulticast() || !cm.Dst.Equal(mDNSLinkLocal.IP) {
continue
}
p.SetTOS(iana.DiffServCS7)
p.SetTTL(16)
_, err = p.WriteTo(b[:n], nil, src)
if err != nil {
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)
}
dst := &net.UDPAddr{IP: group, Port: 1024}
for _, ifi := range []*net.Interface{en0, en1} {
err := p.SetMulticastInterface(ifi)
if err != nil {
log.Fatal(err)
}
p.SetMulticastTTL(2)
_, err = p.WriteTo(b[:n], nil, dst)
if err != nil {
log.Fatal(err)
}
}
}
err = p.LeaveGroup(en1, &net.UDPAddr{IP: group})
if err != nil {
log.Fatal(err)
}
newgroup := net.IPv4(224, 0, 0, 249)
err = p.JoinGroup(en1, &net.UDPAddr{IP: newgroup})
if err != nil {
log.Fatal(err)
}
}
type OSPFHeader struct {
Version byte
Type byte
Len uint16
RouterID uint32
AreaID uint32
Checksum uint16
}
const (
OSPFHeaderLen = 14
OSPFHelloHeaderLen = 20
OSPF_VERSION = 2
OSPF_TYPE_HELLO = iota + 1
OSPF_TYPE_DB_DESCRIPTION
OSPF_TYPE_LS_REQUEST
OSPF_TYPE_LS_UPDATE
OSPF_TYPE_LS_ACK
)
var (
AllSPFRouters = net.IPv4(224, 0, 0, 5)
AllDRouters = net.IPv4(224, 0, 0, 6)
)
func ExamplePacketConn_tracingIPPacketRoute() {
// Tracing an IP packet route to www.google.com.
func ExampleIPOSPFListener() {
var ifs []*net.Interface
en0, err := net.InterfaceByName("en0")
const host = "www.google.com"
ips, err := net.LookupIP(host)
if err != nil {
log.Fatal(err)
}
ifs = append(ifs, en0)
en1, err := net.InterfaceByIndex(911)
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")
}
ifs = append(ifs, en1)
c, err := net.ListenPacket("ip4:89", "0.0.0.0") // OSFP for IPv4
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)
r, err := ipv4.NewRawConn(c)
if err != nil {
if err := p.SetControlMessage(ipv4.FlagTTL|ipv4.FlagSrc|ipv4.FlagDst|ipv4.FlagInterface, true); err != nil {
log.Fatal(err)
}
for _, ifi := range ifs {
err := r.JoinGroup(ifi, &net.IPAddr{IP: AllSPFRouters})
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)
}
err = r.JoinGroup(ifi, &net.IPAddr{IP: AllDRouters})
if err != nil {
if err := p.SetTTL(i); err != nil {
log.Fatal(err)
}
}
err = r.SetControlMessage(ipv4.FlagDst|ipv4.FlagInterface, true)
if err != nil {
log.Fatal(err)
}
r.SetTOS(iana.DiffServCS6)
parseOSPFHeader := func(b []byte) *OSPFHeader {
if len(b) < OSPFHeaderLen {
return nil
}
return &OSPFHeader{
Version: b[0],
Type: b[1],
Len: uint16(b[2])<<8 | uint16(b[3]),
RouterID: uint32(b[4])<<24 | uint32(b[5])<<16 | uint32(b[6])<<8 | uint32(b[7]),
AreaID: uint32(b[8])<<24 | uint32(b[9])<<16 | uint32(b[10])<<8 | uint32(b[11]),
Checksum: uint16(b[12])<<8 | uint16(b[13]),
}
}
b := make([]byte, 1500)
for {
iph, p, _, err := r.ReadFrom(b)
if err != nil {
// 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 iph.Version != ipv4.Version {
continue
if err := p.SetReadDeadline(time.Now().Add(3 * time.Second)); err != nil {
log.Fatal(err)
}
if iph.Dst.IsMulticast() {
if !iph.Dst.Equal(AllSPFRouters) && !iph.Dst.Equal(AllDRouters) {
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)
}
ospfh := parseOSPFHeader(p)
if ospfh == nil {
continue
}
if ospfh.Version != OSPF_VERSION {
continue
rm, err := icmp.ParseMessage(iana.ProtocolICMP, rb[:n])
if err != nil {
log.Fatal(err)
}
switch ospfh.Type {
case OSPF_TYPE_HELLO:
case OSPF_TYPE_DB_DESCRIPTION:
case OSPF_TYPE_LS_REQUEST:
case OSPF_TYPE_LS_UPDATE:
case OSPF_TYPE_LS_ACK:
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 ExampleWriteIPOSPFHello() {
var ifs []*net.Interface
en0, err := net.InterfaceByName("en0")
func ExampleRawConn_advertisingOSPFHello() {
c, err := net.ListenPacket(fmt.Sprintf("ip4:%d", iana.ProtocolOSPFIGP), "0.0.0.0") // OSPF for IPv4
if err != nil {
log.Fatal(err)
}
ifs = append(ifs, en0)
en1, err := net.InterfaceByIndex(911)
defer c.Close()
r, err := ipv4.NewRawConn(c)
if err != nil {
log.Fatal(err)
}
ifs = append(ifs, en1)
c, err := net.ListenPacket("ip4:89", "0.0.0.0") // OSPF for IPv4
en0, err := net.InterfaceByName("en0")
if err != nil {
log.Fatal(err)
}
defer c.Close()
r, err := ipv4.NewRawConn(c)
if err != nil {
allSPFRouters := net.IPAddr{IP: net.IPv4(224, 0, 0, 5)}
if err := r.JoinGroup(en0, &allSPFRouters); err != nil {
log.Fatal(err)
}
for _, ifi := range ifs {
err := r.JoinGroup(ifi, &net.IPAddr{IP: AllSPFRouters})
if err != nil {
log.Fatal(err)
}
err = r.JoinGroup(ifi, &net.IPAddr{IP: AllDRouters})
if err != nil {
log.Fatal(err)
}
}
defer r.LeaveGroup(en0, &allSPFRouters)
hello := make([]byte, OSPFHelloHeaderLen)
ospf := make([]byte, OSPFHeaderLen)
ospf[0] = OSPF_VERSION
ospf[1] = OSPF_TYPE_HELLO
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{}
iph.Version = ipv4.Version
iph.Len = ipv4.HeaderLen
iph.TOS = iana.DiffServCS6
iph.TotalLen = ipv4.HeaderLen + len(ospf)
iph.TTL = 1
iph.Protocol = 89
iph.Dst = AllSPFRouters
for _, ifi := range ifs {
err := r.SetMulticastInterface(ifi)
if err != nil {
return
}
err = r.WriteTo(iph, ospf, nil)
if err != nil {
return
iph := &ipv4.Header{
Version: ipv4.Version,
Len: ipv4.HeaderLen,
TOS: iana.DiffServCS6,
TotalLen: ipv4.HeaderLen + len(ospf),
TTL: 1,
Protocol: iana.ProtocolOSPFIGP,
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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