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dnsclient_unix_test.go
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// Copyright 2013 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.
// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
package net
import (
"context"
"errors"
"fmt"
"internal/poll"
"io/ioutil"
"os"
"path"
"reflect"
"strings"
"sync"
"sync/atomic"
"testing"
"time"
"golang.org/x/net/dns/dnsmessage"
)
var goResolver = Resolver{PreferGo: true}
// Test address from 192.0.2.0/24 block, reserved by RFC 5737 for documentation.
var TestAddr = [4]byte{0xc0, 0x00, 0x02, 0x01}
// Test address from 2001:db8::/32 block, reserved by RFC 3849 for documentation.
var TestAddr6 = [16]byte{0x20, 0x01, 0x0d, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
func mustNewName(name string) dnsmessage.Name {
nn, err := dnsmessage.NewName(name)
if err != nil {
panic(fmt.Sprint("creating name: ", err))
}
return nn
}
func mustQuestion(name string, qtype dnsmessage.Type, class dnsmessage.Class) dnsmessage.Question {
return dnsmessage.Question{
Name: mustNewName(name),
Type: qtype,
Class: class,
}
}
var dnsTransportFallbackTests = []struct {
server string
question dnsmessage.Question
timeout int
rcode dnsmessage.RCode
}{
// Querying "com." with qtype=255 usually makes an answer
// which requires more than 512 bytes.
{"8.8.8.8:53", mustQuestion("com.", dnsmessage.TypeALL, dnsmessage.ClassINET), 2, dnsmessage.RCodeSuccess},
{"8.8.4.4:53", mustQuestion("com.", dnsmessage.TypeALL, dnsmessage.ClassINET), 4, dnsmessage.RCodeSuccess},
}
func TestDNSTransportFallback(t *testing.T) {
fake := fakeDNSServer{
rh: func(n, _ string, q dnsmessage.Message, _ time.Time) (dnsmessage.Message, error) {
r := dnsmessage.Message{
Header: dnsmessage.Header{
ID: q.Header.ID,
Response: true,
RCode: dnsmessage.RCodeSuccess,
},
Questions: q.Questions,
}
if n == "udp" {
r.Header.Truncated = true
}
return r, nil
},
}
r := Resolver{PreferGo: true, Dial: fake.DialContext}
for _, tt := range dnsTransportFallbackTests {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
_, h, err := r.exchange(ctx, tt.server, tt.question, time.Second, useUDPOrTCP)
if err != nil {
t.Error(err)
continue
}
if h.RCode != tt.rcode {
t.Errorf("got %v from %v; want %v", h.RCode, tt.server, tt.rcode)
continue
}
}
}
// See RFC 6761 for further information about the reserved, pseudo
// domain names.
var specialDomainNameTests = []struct {
question dnsmessage.Question
rcode dnsmessage.RCode
}{
// Name resolution APIs and libraries should not recognize the
// followings as special.
{mustQuestion("1.0.168.192.in-addr.arpa.", dnsmessage.TypePTR, dnsmessage.ClassINET), dnsmessage.RCodeNameError},
{mustQuestion("test.", dnsmessage.TypeALL, dnsmessage.ClassINET), dnsmessage.RCodeNameError},
{mustQuestion("example.com.", dnsmessage.TypeALL, dnsmessage.ClassINET), dnsmessage.RCodeSuccess},
// Name resolution APIs and libraries should recognize the
// followings as special and should not send any queries.
// Though, we test those names here for verifying negative
// answers at DNS query-response interaction level.
{mustQuestion("localhost.", dnsmessage.TypeALL, dnsmessage.ClassINET), dnsmessage.RCodeNameError},
{mustQuestion("invalid.", dnsmessage.TypeALL, dnsmessage.ClassINET), dnsmessage.RCodeNameError},
}
func TestSpecialDomainName(t *testing.T) {
fake := fakeDNSServer{rh: func(_, _ string, q dnsmessage.Message, _ time.Time) (dnsmessage.Message, error) {
r := dnsmessage.Message{
Header: dnsmessage.Header{
ID: q.ID,
Response: true,
},
Questions: q.Questions,
}
switch q.Questions[0].Name.String() {
case "example.com.":
r.Header.RCode = dnsmessage.RCodeSuccess
default:
r.Header.RCode = dnsmessage.RCodeNameError
}
return r, nil
}}
r := Resolver{PreferGo: true, Dial: fake.DialContext}
server := "8.8.8.8:53"
for _, tt := range specialDomainNameTests {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
_, h, err := r.exchange(ctx, server, tt.question, 3*time.Second, useUDPOrTCP)
if err != nil {
t.Error(err)
continue
}
if h.RCode != tt.rcode {
t.Errorf("got %v from %v; want %v", h.RCode, server, tt.rcode)
continue
}
}
}
// Issue 13705: don't try to resolve onion addresses, etc
func TestAvoidDNSName(t *testing.T) {
tests := []struct {
name string
avoid bool
}{
{"foo.com", false},
{"foo.com.", false},
{"foo.onion.", true},
{"foo.onion", true},
{"foo.ONION", true},
{"foo.ONION.", true},
// But do resolve *.local address; Issue 16739
{"foo.local.", false},
{"foo.local", false},
{"foo.LOCAL", false},
{"foo.LOCAL.", false},
{"", true}, // will be rejected earlier too
// Without stuff before onion/local, they're fine to
// use DNS. With a search path,
// "onion.vegetables.com" can use DNS. Without a
// search path (or with a trailing dot), the queries
// are just kinda useless, but don't reveal anything
// private.
{"local", false},
{"onion", false},
{"local.", false},
{"onion.", false},
}
for _, tt := range tests {
got := avoidDNS(tt.name)
if got != tt.avoid {
t.Errorf("avoidDNS(%q) = %v; want %v", tt.name, got, tt.avoid)
}
}
}
var fakeDNSServerSuccessful = fakeDNSServer{rh: func(_, _ string, q dnsmessage.Message, _ time.Time) (dnsmessage.Message, error) {
r := dnsmessage.Message{
Header: dnsmessage.Header{
ID: q.ID,
Response: true,
},
Questions: q.Questions,
}
if len(q.Questions) == 1 && q.Questions[0].Type == dnsmessage.TypeA {
r.Answers = []dnsmessage.Resource{
{
Header: dnsmessage.ResourceHeader{
Name: q.Questions[0].Name,
Type: dnsmessage.TypeA,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.AResource{
A: TestAddr,
},
},
}
}
return r, nil
}}
// Issue 13705: don't try to resolve onion addresses, etc
func TestLookupTorOnion(t *testing.T) {
defer dnsWaitGroup.Wait()
r := Resolver{PreferGo: true, Dial: fakeDNSServerSuccessful.DialContext}
addrs, err := r.LookupIPAddr(context.Background(), "foo.onion")
if err != nil {
t.Fatalf("lookup = %v; want nil", err)
}
if len(addrs) > 0 {
t.Errorf("unexpected addresses: %v", addrs)
}
}
type resolvConfTest struct {
dir string
path string
*resolverConfig
}
func newResolvConfTest() (*resolvConfTest, error) {
dir, err := ioutil.TempDir("", "go-resolvconftest")
if err != nil {
return nil, err
}
conf := &resolvConfTest{
dir: dir,
path: path.Join(dir, "resolv.conf"),
resolverConfig: &resolvConf,
}
conf.initOnce.Do(conf.init)
return conf, nil
}
func (conf *resolvConfTest) writeAndUpdate(lines []string) error {
f, err := os.OpenFile(conf.path, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0600)
if err != nil {
return err
}
if _, err := f.WriteString(strings.Join(lines, "\n")); err != nil {
f.Close()
return err
}
f.Close()
if err := conf.forceUpdate(conf.path, time.Now().Add(time.Hour)); err != nil {
return err
}
return nil
}
func (conf *resolvConfTest) forceUpdate(name string, lastChecked time.Time) error {
dnsConf := dnsReadConfig(name)
conf.mu.Lock()
conf.dnsConfig = dnsConf
conf.mu.Unlock()
for i := 0; i < 5; i++ {
if conf.tryAcquireSema() {
conf.lastChecked = lastChecked
conf.releaseSema()
return nil
}
}
return fmt.Errorf("tryAcquireSema for %s failed", name)
}
func (conf *resolvConfTest) servers() []string {
conf.mu.RLock()
servers := conf.dnsConfig.servers
conf.mu.RUnlock()
return servers
}
func (conf *resolvConfTest) teardown() error {
err := conf.forceUpdate("/etc/resolv.conf", time.Time{})
os.RemoveAll(conf.dir)
return err
}
var updateResolvConfTests = []struct {
name string // query name
lines []string // resolver configuration lines
servers []string // expected name servers
}{
{
name: "golang.org",
lines: []string{"nameserver 8.8.8.8"},
servers: []string{"8.8.8.8:53"},
},
{
name: "",
lines: nil, // an empty resolv.conf should use defaultNS as name servers
servers: defaultNS,
},
{
name: "www.example.com",
lines: []string{"nameserver 8.8.4.4"},
servers: []string{"8.8.4.4:53"},
},
}
func TestUpdateResolvConf(t *testing.T) {
defer dnsWaitGroup.Wait()
r := Resolver{PreferGo: true, Dial: fakeDNSServerSuccessful.DialContext}
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
}
defer conf.teardown()
for i, tt := range updateResolvConfTests {
if err := conf.writeAndUpdate(tt.lines); err != nil {
t.Error(err)
continue
}
if tt.name != "" {
var wg sync.WaitGroup
const N = 10
wg.Add(N)
for j := 0; j < N; j++ {
go func(name string) {
defer wg.Done()
ips, err := r.LookupIPAddr(context.Background(), name)
if err != nil {
t.Error(err)
return
}
if len(ips) == 0 {
t.Errorf("no records for %s", name)
return
}
}(tt.name)
}
wg.Wait()
}
servers := conf.servers()
if !reflect.DeepEqual(servers, tt.servers) {
t.Errorf("#%d: got %v; want %v", i, servers, tt.servers)
continue
}
}
}
var goLookupIPWithResolverConfigTests = []struct {
name string
lines []string // resolver configuration lines
error
a, aaaa bool // whether response contains A, AAAA-record
}{
// no records, transport timeout
{
"jgahvsekduiv9bw4b3qhn4ykdfgj0493iohkrjfhdvhjiu4j",
[]string{
"options timeout:1 attempts:1",
"nameserver 255.255.255.255", // please forgive us for abuse of limited broadcast address
},
&DNSError{Name: "jgahvsekduiv9bw4b3qhn4ykdfgj0493iohkrjfhdvhjiu4j", Server: "255.255.255.255:53", IsTimeout: true},
false, false,
},
// no records, non-existent domain
{
"jgahvsekduiv9bw4b3qhn4ykdfgj0493iohkrjfhdvhjiu4j",
[]string{
"options timeout:3 attempts:1",
"nameserver 8.8.8.8",
},
&DNSError{Name: "jgahvsekduiv9bw4b3qhn4ykdfgj0493iohkrjfhdvhjiu4j", Server: "8.8.8.8:53", IsTimeout: false},
false, false,
},
// a few A records, no AAAA records
{
"ipv4.google.com.",
[]string{
"nameserver 8.8.8.8",
"nameserver 2001:4860:4860::8888",
},
nil,
true, false,
},
{
"ipv4.google.com",
[]string{
"domain golang.org",
"nameserver 2001:4860:4860::8888",
"nameserver 8.8.8.8",
},
nil,
true, false,
},
{
"ipv4.google.com",
[]string{
"search x.golang.org y.golang.org",
"nameserver 2001:4860:4860::8888",
"nameserver 8.8.8.8",
},
nil,
true, false,
},
// no A records, a few AAAA records
{
"ipv6.google.com.",
[]string{
"nameserver 2001:4860:4860::8888",
"nameserver 8.8.8.8",
},
nil,
false, true,
},
{
"ipv6.google.com",
[]string{
"domain golang.org",
"nameserver 8.8.8.8",
"nameserver 2001:4860:4860::8888",
},
nil,
false, true,
},
{
"ipv6.google.com",
[]string{
"search x.golang.org y.golang.org",
"nameserver 8.8.8.8",
"nameserver 2001:4860:4860::8888",
},
nil,
false, true,
},
// both A and AAAA records
{
"hostname.as112.net", // see RFC 7534
[]string{
"domain golang.org",
"nameserver 2001:4860:4860::8888",
"nameserver 8.8.8.8",
},
nil,
true, true,
},
{
"hostname.as112.net", // see RFC 7534
[]string{
"search x.golang.org y.golang.org",
"nameserver 2001:4860:4860::8888",
"nameserver 8.8.8.8",
},
nil,
true, true,
},
}
func TestGoLookupIPWithResolverConfig(t *testing.T) {
defer dnsWaitGroup.Wait()
fake := fakeDNSServer{rh: func(n, s string, q dnsmessage.Message, _ time.Time) (dnsmessage.Message, error) {
switch s {
case "[2001:4860:4860::8888]:53", "8.8.8.8:53":
break
default:
time.Sleep(10 * time.Millisecond)
return dnsmessage.Message{}, poll.ErrTimeout
}
r := dnsmessage.Message{
Header: dnsmessage.Header{
ID: q.ID,
Response: true,
},
Questions: q.Questions,
}
for _, question := range q.Questions {
switch question.Type {
case dnsmessage.TypeA:
switch question.Name.String() {
case "hostname.as112.net.":
break
case "ipv4.google.com.":
r.Answers = append(r.Answers, dnsmessage.Resource{
Header: dnsmessage.ResourceHeader{
Name: q.Questions[0].Name,
Type: dnsmessage.TypeA,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.AResource{
A: TestAddr,
},
})
default:
}
case dnsmessage.TypeAAAA:
switch question.Name.String() {
case "hostname.as112.net.":
break
case "ipv6.google.com.":
r.Answers = append(r.Answers, dnsmessage.Resource{
Header: dnsmessage.ResourceHeader{
Name: q.Questions[0].Name,
Type: dnsmessage.TypeAAAA,
Class: dnsmessage.ClassINET,
Length: 16,
},
Body: &dnsmessage.AAAAResource{
AAAA: TestAddr6,
},
})
}
}
}
return r, nil
}}
r := Resolver{PreferGo: true, Dial: fake.DialContext}
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
}
defer conf.teardown()
for _, tt := range goLookupIPWithResolverConfigTests {
if err := conf.writeAndUpdate(tt.lines); err != nil {
t.Error(err)
continue
}
addrs, err := r.LookupIPAddr(context.Background(), tt.name)
if err != nil {
if err, ok := err.(*DNSError); !ok || tt.error != nil && (err.Name != tt.error.(*DNSError).Name || err.Server != tt.error.(*DNSError).Server || err.IsTimeout != tt.error.(*DNSError).IsTimeout) {
t.Errorf("got %v; want %v", err, tt.error)
}
continue
}
if len(addrs) == 0 {
t.Errorf("no records for %s", tt.name)
}
if !tt.a && !tt.aaaa && len(addrs) > 0 {
t.Errorf("unexpected %v for %s", addrs, tt.name)
}
for _, addr := range addrs {
if !tt.a && addr.IP.To4() != nil {
t.Errorf("got %v; must not be IPv4 address", addr)
}
if !tt.aaaa && addr.IP.To16() != nil && addr.IP.To4() == nil {
t.Errorf("got %v; must not be IPv6 address", addr)
}
}
}
}
// Test that goLookupIPOrder falls back to the host file when no DNS servers are available.
func TestGoLookupIPOrderFallbackToFile(t *testing.T) {
defer dnsWaitGroup.Wait()
fake := fakeDNSServer{rh: func(n, s string, q dnsmessage.Message, tm time.Time) (dnsmessage.Message, error) {
r := dnsmessage.Message{
Header: dnsmessage.Header{
ID: q.ID,
Response: true,
},
Questions: q.Questions,
}
return r, nil
}}
r := Resolver{PreferGo: true, Dial: fake.DialContext}
// Add a config that simulates no dns servers being available.
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
}
defer conf.teardown()
if err := conf.writeAndUpdate([]string{}); err != nil {
t.Fatal(err)
}
// Redirect host file lookups.
defer func(orig string) { testHookHostsPath = orig }(testHookHostsPath)
testHookHostsPath = "testdata/hosts"
for _, order := range []hostLookupOrder{hostLookupFilesDNS, hostLookupDNSFiles} {
name := fmt.Sprintf("order %v", order)
// First ensure that we get an error when contacting a non-existent host.
_, _, err := r.goLookupIPCNAMEOrder(context.Background(), "notarealhost", order)
if err == nil {
t.Errorf("%s: expected error while looking up name not in hosts file", name)
continue
}
// Now check that we get an address when the name appears in the hosts file.
addrs, _, err := r.goLookupIPCNAMEOrder(context.Background(), "thor", order) // entry is in "testdata/hosts"
if err != nil {
t.Errorf("%s: expected to successfully lookup host entry", name)
continue
}
if len(addrs) != 1 {
t.Errorf("%s: expected exactly one result, but got %v", name, addrs)
continue
}
if got, want := addrs[0].String(), "127.1.1.1"; got != want {
t.Errorf("%s: address doesn't match expectation. got %v, want %v", name, got, want)
}
}
}
// Issue 12712.
// When using search domains, return the error encountered
// querying the original name instead of an error encountered
// querying a generated name.
func TestErrorForOriginalNameWhenSearching(t *testing.T) {
defer dnsWaitGroup.Wait()
const fqdn = "doesnotexist.domain"
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
}
defer conf.teardown()
if err := conf.writeAndUpdate([]string{"search servfail"}); err != nil {
t.Fatal(err)
}
fake := fakeDNSServer{rh: func(_, _ string, q dnsmessage.Message, _ time.Time) (dnsmessage.Message, error) {
r := dnsmessage.Message{
Header: dnsmessage.Header{
ID: q.ID,
Response: true,
},
Questions: q.Questions,
}
switch q.Questions[0].Name.String() {
case fqdn + ".servfail.":
r.Header.RCode = dnsmessage.RCodeServerFailure
default:
r.Header.RCode = dnsmessage.RCodeNameError
}
return r, nil
}}
cases := []struct {
strictErrors bool
wantErr *DNSError
}{
{true, &DNSError{Name: fqdn, Err: "server misbehaving", IsTemporary: true}},
{false, &DNSError{Name: fqdn, Err: errNoSuchHost.Error(), IsNotFound: true}},
}
for _, tt := range cases {
r := Resolver{PreferGo: true, StrictErrors: tt.strictErrors, Dial: fake.DialContext}
_, err = r.LookupIPAddr(context.Background(), fqdn)
if err == nil {
t.Fatal("expected an error")
}
want := tt.wantErr
if err, ok := err.(*DNSError); !ok || err.Name != want.Name || err.Err != want.Err || err.IsTemporary != want.IsTemporary {
t.Errorf("got %v; want %v", err, want)
}
}
}
// Issue 15434. If a name server gives a lame referral, continue to the next.
func TestIgnoreLameReferrals(t *testing.T) {
defer dnsWaitGroup.Wait()
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
}
defer conf.teardown()
if err := conf.writeAndUpdate([]string{"nameserver 192.0.2.1", // the one that will give a lame referral
"nameserver 192.0.2.2"}); err != nil {
t.Fatal(err)
}
fake := fakeDNSServer{rh: func(_, s string, q dnsmessage.Message, _ time.Time) (dnsmessage.Message, error) {
t.Log(s, q)
r := dnsmessage.Message{
Header: dnsmessage.Header{
ID: q.ID,
Response: true,
},
Questions: q.Questions,
}
if s == "192.0.2.2:53" {
r.Header.RecursionAvailable = true
if q.Questions[0].Type == dnsmessage.TypeA {
r.Answers = []dnsmessage.Resource{
{
Header: dnsmessage.ResourceHeader{
Name: q.Questions[0].Name,
Type: dnsmessage.TypeA,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.AResource{
A: TestAddr,
},
},
}
}
}
return r, nil
}}
r := Resolver{PreferGo: true, Dial: fake.DialContext}
addrs, err := r.LookupIPAddr(context.Background(), "www.golang.org")
if err != nil {
t.Fatal(err)
}
if got := len(addrs); got != 1 {
t.Fatalf("got %d addresses, want 1", got)
}
if got, want := addrs[0].String(), "192.0.2.1"; got != want {
t.Fatalf("got address %v, want %v", got, want)
}
}
func BenchmarkGoLookupIP(b *testing.B) {
testHookUninstaller.Do(uninstallTestHooks)
ctx := context.Background()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
goResolver.LookupIPAddr(ctx, "www.example.com")
}
}
func BenchmarkGoLookupIPNoSuchHost(b *testing.B) {
testHookUninstaller.Do(uninstallTestHooks)
ctx := context.Background()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
goResolver.LookupIPAddr(ctx, "some.nonexistent")
}
}
func BenchmarkGoLookupIPWithBrokenNameServer(b *testing.B) {
testHookUninstaller.Do(uninstallTestHooks)
conf, err := newResolvConfTest()
if err != nil {
b.Fatal(err)
}
defer conf.teardown()
lines := []string{
"nameserver 203.0.113.254", // use TEST-NET-3 block, see RFC 5737
"nameserver 8.8.8.8",
}
if err := conf.writeAndUpdate(lines); err != nil {
b.Fatal(err)
}
ctx := context.Background()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
goResolver.LookupIPAddr(ctx, "www.example.com")
}
}
type fakeDNSServer struct {
rh func(n, s string, q dnsmessage.Message, t time.Time) (dnsmessage.Message, error)
alwaysTCP bool
}
func (server *fakeDNSServer) DialContext(_ context.Context, n, s string) (Conn, error) {
if server.alwaysTCP || n == "tcp" || n == "tcp4" || n == "tcp6" {
return &fakeDNSConn{tcp: true, server: server, n: n, s: s}, nil
}
return &fakeDNSPacketConn{fakeDNSConn: fakeDNSConn{tcp: false, server: server, n: n, s: s}}, nil
}
type fakeDNSConn struct {
Conn
tcp bool
server *fakeDNSServer
n string
s string
q dnsmessage.Message
t time.Time
buf []byte
}
func (f *fakeDNSConn) Close() error {
return nil
}
func (f *fakeDNSConn) Read(b []byte) (int, error) {
if len(f.buf) > 0 {
n := copy(b, f.buf)
f.buf = f.buf[n:]
return n, nil
}
resp, err := f.server.rh(f.n, f.s, f.q, f.t)
if err != nil {
return 0, err
}
bb := make([]byte, 2, 514)
bb, err = resp.AppendPack(bb)
if err != nil {
return 0, fmt.Errorf("cannot marshal DNS message: %v", err)
}
if f.tcp {
l := len(bb) - 2
bb[0] = byte(l >> 8)
bb[1] = byte(l)
f.buf = bb
return f.Read(b)
}
bb = bb[2:]
if len(b) < len(bb) {
return 0, errors.New("read would fragment DNS message")
}
copy(b, bb)
return len(bb), nil
}
func (f *fakeDNSConn) Write(b []byte) (int, error) {
if f.tcp && len(b) >= 2 {
b = b[2:]
}
if f.q.Unpack(b) != nil {
return 0, fmt.Errorf("cannot unmarshal DNS message fake %s (%d)", f.n, len(b))
}
return len(b), nil
}
func (f *fakeDNSConn) SetDeadline(t time.Time) error {
f.t = t
return nil
}
type fakeDNSPacketConn struct {
PacketConn
fakeDNSConn
}
func (f *fakeDNSPacketConn) SetDeadline(t time.Time) error {
return f.fakeDNSConn.SetDeadline(t)
}
func (f *fakeDNSPacketConn) Close() error {
return f.fakeDNSConn.Close()
}
// UDP round-tripper algorithm should ignore invalid DNS responses (issue 13281).
func TestIgnoreDNSForgeries(t *testing.T) {
c, s := Pipe()
go func() {
b := make([]byte, 512)
n, err := s.Read(b)
if err != nil {
t.Error(err)
return
}
var msg dnsmessage.Message
if msg.Unpack(b[:n]) != nil {
t.Error("invalid DNS query:", err)
return
}
s.Write([]byte("garbage DNS response packet"))
msg.Header.Response = true
msg.Header.ID++ // make invalid ID
if b, err = msg.Pack(); err != nil {
t.Error("failed to pack DNS response:", err)
return
}
s.Write(b)
msg.Header.ID-- // restore original ID
msg.Answers = []dnsmessage.Resource{
{
Header: dnsmessage.ResourceHeader{
Name: mustNewName("www.example.com."),
Type: dnsmessage.TypeA,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.AResource{
A: TestAddr,
},
},
}
b, err = msg.Pack()
if err != nil {
t.Error("failed to pack DNS response:", err)
return
}
s.Write(b)
}()
msg := dnsmessage.Message{
Header: dnsmessage.Header{
ID: 42,
},
Questions: []dnsmessage.Question{
{
Name: mustNewName("www.example.com."),
Type: dnsmessage.TypeA,
Class: dnsmessage.ClassINET,
},
},
}
b, err := msg.Pack()
if err != nil {
t.Fatal("Pack failed:", err)
}
p, _, err := dnsPacketRoundTrip(c, 42, msg.Questions[0], b)
if err != nil {
t.Fatalf("dnsPacketRoundTrip failed: %v", err)
}
p.SkipAllQuestions()
as, err := p.AllAnswers()
if err != nil {
t.Fatal("AllAnswers failed:", err)
}
if got := as[0].Body.(*dnsmessage.AResource).A; got != TestAddr {
t.Errorf("got address %v, want %v", got, TestAddr)
}
}
// Issue 16865. If a name server times out, continue to the next.
func TestRetryTimeout(t *testing.T) {
defer dnsWaitGroup.Wait()
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
}
defer conf.teardown()
testConf := []string{
"nameserver 192.0.2.1", // the one that will timeout
"nameserver 192.0.2.2",
}
if err := conf.writeAndUpdate(testConf); err != nil {
t.Fatal(err)
}
var deadline0 time.Time
fake := fakeDNSServer{rh: func(_, s string, q dnsmessage.Message, deadline time.Time) (dnsmessage.Message, error) {
t.Log(s, q, deadline)
if deadline.IsZero() {
t.Error("zero deadline")
}
if s == "192.0.2.1:53" {
deadline0 = deadline
time.Sleep(10 * time.Millisecond)
return dnsmessage.Message{}, poll.ErrTimeout
}
if deadline.Equal(deadline0) {
t.Error("deadline didn't change")