Golang程序
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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 darwin dragonfly freebsd linux netbsd openbsd solaris
package net
import (
"context"
"errors"
"fmt"
"internal/poll"
"io/ioutil"
"os"
"path"
"reflect"
"strings"
"sync"
"testing"
"time"
)
var goResolver = Resolver{PreferGo: true}
// Test address from 192.0.2.0/24 block, reserved by RFC 5737 for documentation.
const TestAddr uint32 = 0xc0000201
// 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}
var dnsTransportFallbackTests = []struct {
server string
name string
qtype uint16
timeout int
rcode int
}{
// Querying "com." with qtype=255 usually makes an answer
// which requires more than 512 bytes.
{"8.8.8.8:53", "com.", dnsTypeALL, 2, dnsRcodeSuccess},
{"8.8.4.4:53", "com.", dnsTypeALL, 4, dnsRcodeSuccess},
}
func TestDNSTransportFallback(t *testing.T) {
fake := fakeDNSServer{
rh: func(n, _ string, q *dnsMsg, _ time.Time) (*dnsMsg, error) {
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
response: true,
rcode: dnsRcodeSuccess,
},
question: q.question,
}
if n == "udp" {
r.truncated = true
}
return r, nil
},
}
r := Resolver{PreferGo: true, Dial: fake.DialContext}
for _, tt := range dnsTransportFallbackTests {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
msg, err := r.exchange(ctx, tt.server, tt.name, tt.qtype, time.Second)
if err != nil {
t.Error(err)
continue
}
switch msg.rcode {
case tt.rcode:
default:
t.Errorf("got %v from %v; want %v", msg.rcode, tt.server, tt.rcode)
continue
}
}
}
// See RFC 6761 for further information about the reserved, pseudo
// domain names.
var specialDomainNameTests = []struct {
name string
qtype uint16
rcode int
}{
// Name resolution APIs and libraries should not recognize the
// followings as special.
{"1.0.168.192.in-addr.arpa.", dnsTypePTR, dnsRcodeNameError},
{"test.", dnsTypeALL, dnsRcodeNameError},
{"example.com.", dnsTypeALL, dnsRcodeSuccess},
// 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.
{"localhost.", dnsTypeALL, dnsRcodeNameError},
{"invalid.", dnsTypeALL, dnsRcodeNameError},
}
func TestSpecialDomainName(t *testing.T) {
fake := fakeDNSServer{func(_, _ string, q *dnsMsg, _ time.Time) (*dnsMsg, error) {
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
response: true,
},
question: q.question,
}
switch q.question[0].Name {
case "example.com.":
r.rcode = dnsRcodeSuccess
default:
r.rcode = dnsRcodeNameError
}
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()
msg, err := r.exchange(ctx, server, tt.name, tt.qtype, 3*time.Second)
if err != nil {
t.Error(err)
continue
}
switch msg.rcode {
case tt.rcode, dnsRcodeServerFailure:
default:
t.Errorf("got %v from %v; want %v", msg.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.vegegtables.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{func(_, _ string, q *dnsMsg, _ time.Time) (*dnsMsg, error) {
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
response: true,
},
question: q.question,
}
if len(q.question) == 1 && q.question[0].Qtype == dnsTypeA {
r.answer = []dnsRR{
&dnsRR_A{
Hdr: dnsRR_Header{
Name: q.question[0].Name,
Rrtype: dnsTypeA,
Class: dnsClassINET,
Rdlength: 4,
},
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{func(n, s string, q *dnsMsg, _ time.Time) (*dnsMsg, error) {
switch s {
case "[2001:4860:4860::8888]:53", "8.8.8.8:53":
break
default:
time.Sleep(10 * time.Millisecond)
return nil, poll.ErrTimeout
}
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
response: true,
},
question: q.question,
}
for _, question := range q.question {
switch question.Qtype {
case dnsTypeA:
switch question.Name {
case "hostname.as112.net.":
break
case "ipv4.google.com.":
r.answer = append(r.answer, &dnsRR_A{
Hdr: dnsRR_Header{
Name: q.question[0].Name,
Rrtype: dnsTypeA,
Class: dnsClassINET,
Rdlength: 4,
},
A: TestAddr,
})
default:
}
case dnsTypeAAAA:
switch question.Name {
case "hostname.as112.net.":
break
case "ipv6.google.com.":
r.answer = append(r.answer, &dnsRR_AAAA{
Hdr: dnsRR_Header{
Name: q.question[0].Name,
Rrtype: dnsTypeAAAA,
Class: dnsClassINET,
Rdlength: 16,
},
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{func(n, s string, q *dnsMsg, tm time.Time) (*dnsMsg, error) {
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
response: true,
},
question: q.question,
}
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)
}
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)
}
}
defer conf.teardown()
}
// 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{func(_, _ string, q *dnsMsg, _ time.Time) (*dnsMsg, error) {
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
response: true,
},
question: q.question,
}
switch q.question[0].Name {
case fqdn + ".servfail.":
r.rcode = dnsRcodeServerFailure
default:
r.rcode = dnsRcodeNameError
}
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()}},
}
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{func(_, s string, q *dnsMsg, _ time.Time) (*dnsMsg, error) {
t.Log(s, q)
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
response: true,
},
question: q.question,
}
if s == "192.0.2.2:53" {
r.recursion_available = true
if q.question[0].Qtype == dnsTypeA {
r.answer = []dnsRR{
&dnsRR_A{
Hdr: dnsRR_Header{
Name: q.question[0].Name,
Rrtype: dnsTypeA,
Class: dnsClassINET,
Rdlength: 4,
},
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()
for i := 0; i < b.N; i++ {
goResolver.LookupIPAddr(ctx, "www.example.com")
}
}
func BenchmarkGoLookupIPNoSuchHost(b *testing.B) {
testHookUninstaller.Do(uninstallTestHooks)
ctx := context.Background()
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()
for i := 0; i < b.N; i++ {
goResolver.LookupIPAddr(ctx, "www.example.com")
}
}
type fakeDNSServer struct {
rh func(n, s string, q *dnsMsg, t time.Time) (*dnsMsg, error)
}
func (server *fakeDNSServer) DialContext(_ context.Context, n, s string) (Conn, error) {
return &fakeDNSConn{nil, server, n, s, nil, time.Time{}}, nil
}
type fakeDNSConn struct {
Conn
server *fakeDNSServer
n string
s string
q *dnsMsg
t time.Time
}
func (f *fakeDNSConn) Close() error {
return nil
}
func (f *fakeDNSConn) Read(b []byte) (int, error) {
resp, err := f.server.rh(f.n, f.s, f.q, f.t)
if err != nil {
return 0, err
}
bb, ok := resp.Pack()
if !ok {
return 0, errors.New("cannot marshal DNS message")
}
if len(b) < len(bb) {
return 0, errors.New("read would fragment DNS message")
}
copy(b, bb)
return len(bb), nil
}
func (f *fakeDNSConn) ReadFrom(b []byte) (int, Addr, error) {
return 0, nil, nil
}
func (f *fakeDNSConn) Write(b []byte) (int, error) {
f.q = new(dnsMsg)
if !f.q.Unpack(b) {
return 0, errors.New("cannot unmarshal DNS message")
}
return len(b), nil
}
func (f *fakeDNSConn) WriteTo(b []byte, addr Addr) (int, error) {
return 0, nil
}
func (f *fakeDNSConn) SetDeadline(t time.Time) error {
f.t = t
return nil
}
// 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
}
msg := &dnsMsg{}
if !msg.Unpack(b[:n]) {
t.Error("invalid DNS query")
return
}
s.Write([]byte("garbage DNS response packet"))
msg.response = true
msg.id++ // make invalid ID
b, ok := msg.Pack()
if !ok {
t.Error("failed to pack DNS response")
return
}
s.Write(b)
msg.id-- // restore original ID
msg.answer = []dnsRR{
&dnsRR_A{
Hdr: dnsRR_Header{
Name: "www.example.com.",
Rrtype: dnsTypeA,
Class: dnsClassINET,
Rdlength: 4,
},
A: TestAddr,
},
}
b, ok = msg.Pack()
if !ok {
t.Error("failed to pack DNS response")
return
}
s.Write(b)
}()
msg := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: 42,
},
question: []dnsQuestion{
{
Name: "www.example.com.",
Qtype: dnsTypeA,
Qclass: dnsClassINET,
},
},
}
dc := &dnsPacketConn{c}
resp, err := dc.dnsRoundTrip(msg)
if err != nil {
t.Fatalf("dnsRoundTripUDP failed: %v", err)
}
if got := resp.answer[0].(*dnsRR_A).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{func(_, s string, q *dnsMsg, deadline time.Time) (*dnsMsg, 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 nil, poll.ErrTimeout
}
if deadline.Equal(deadline0) {
t.Error("deadline didn't change")
}
return mockTXTResponse(q), nil
}}
r := &Resolver{PreferGo: true, Dial: fake.DialContext}
_, err = r.LookupTXT(context.Background(), "www.golang.org")
if err != nil {
t.Fatal(err)
}
if deadline0.IsZero() {
t.Error("deadline0 still zero", deadline0)
}
}
func TestRotate(t *testing.T) {
// without rotation, always uses the first server
testRotate(t, false, []string{"192.0.2.1", "192.0.2.2"}, []string{"192.0.2.1:53", "192.0.2.1:53", "192.0.2.1:53"})
// with rotation, rotates through back to first
testRotate(t, true, []string{"192.0.2.1", "192.0.2.2"}, []string{"192.0.2.1:53", "192.0.2.2:53", "192.0.2.1:53"})
}
func testRotate(t *testing.T, rotate bool, nameservers, wantServers []string) {
defer dnsWaitGroup.Wait()
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
}
defer conf.teardown()
var confLines []string
for _, ns := range nameservers {
confLines = append(confLines, "nameserver "+ns)
}
if rotate {
confLines = append(confLines, "options rotate")
}
if err := conf.writeAndUpdate(confLines); err != nil {
t.Fatal(err)
}
var usedServers []string
fake := fakeDNSServer{func(_, s string, q *dnsMsg, deadline time.Time) (*dnsMsg, error) {
usedServers = append(usedServers, s)
return mockTXTResponse(q), nil
}}
r := Resolver{PreferGo: true, Dial: fake.DialContext}
// len(nameservers) + 1 to allow rotation to get back to start
for i := 0; i < len(nameservers)+1; i++ {
if _, err := r.LookupTXT(context.Background(), "www.golang.org"); err != nil {
t.Fatal(err)
}
}
if !reflect.DeepEqual(usedServers, wantServers) {
t.Errorf("rotate=%t got used servers:\n%v\nwant:\n%v", rotate, usedServers, wantServers)
}
}
func mockTXTResponse(q *dnsMsg) *dnsMsg {
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
response: true,
recursion_available: true,
},
question: q.question,
answer: []dnsRR{
&dnsRR_TXT{
Hdr: dnsRR_Header{
Name: q.question[0].Name,
Rrtype: dnsTypeTXT,
Class: dnsClassINET,
},
Txt: "ok",
},
},
}
return r
}
// Issue 17448. With StrictErrors enabled, temporary errors should make
// LookupIP fail rather than return a partial result.
func TestStrictErrorsLookupIP(t *testing.T) {
defer dnsWaitGroup.Wait()
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
}
defer conf.teardown()
confData := []string{
"nameserver 192.0.2.53",
"search x.golang.org y.golang.org",
}
if err := conf.writeAndUpdate(confData); err != nil {
t.Fatal(err)
}
const name = "test-issue19592"
const server = "192.0.2.53:53"
const searchX = "test-issue19592.x.golang.org."
const searchY = "test-issue19592.y.golang.org."
const ip4 = "192.0.2.1"
const ip6 = "2001:db8::1"
type resolveWhichEnum int
const (
resolveOK resolveWhichEnum = iota
resolveOpError
resolveServfail
resolveTimeout
)
makeTempError := func(err string) error {
return &DNSError{
Err: err,
Name: name,
Server: server,
IsTemporary: true,
}
}
makeTimeout := func() error {
return &DNSError{
Err: poll.ErrTimeout.Error(),
Name: name,
Server: server,
IsTimeout: true,
}
}
makeNxDomain := func() error {
return &DNSError{
Err: errNoSuchHost.Error(),
Name: name,
Server: server,
}
}
cases := []struct {
desc string
resolveWhich func(quest *dnsQuestion) resolveWhichEnum
wantStrictErr error
wantLaxErr error
wantIPs []string
}{
{
desc: "No errors",
resolveWhich: func(quest *dnsQuestion) resolveWhichEnum {
return resolveOK
},
wantIPs: []string{ip4, ip6},
},
{
desc: "searchX error fails in strict mode",
resolveWhich: func(quest *dnsQuestion) resolveWhichEnum {
if quest.Name == searchX {
return resolveTimeout
}
return resolveOK
},
wantStrictErr: makeTimeout(),
wantIPs: []string{ip4, ip6},
},
{
desc: "searchX IPv4-only timeout fails in strict mode",
resolveWhich: func(quest *dnsQuestion) resolveWhichEnum {
if quest.Name == searchX && quest.Qtype == dnsTypeA {
return resolveTimeout
}
return resolveOK
},
wantStrictErr: makeTimeout(),
wantIPs: []string{ip4, ip6},
},
{
desc: "searchX IPv6-only servfail fails in strict mode",
resolveWhich: func(quest *dnsQuestion) resolveWhichEnum {
if quest.Name == searchX && quest.Qtype == dnsTypeAAAA {
return resolveServfail
}
return resolveOK
},
wantStrictErr: makeTempError("server misbehaving"),
wantIPs: []string{ip4, ip6},
},
{
desc: "searchY error always fails",
resolveWhich: func(quest *dnsQuestion) resolveWhichEnum {
if quest.Name == searchY {
return resolveTimeout
}
return resolveOK
},
wantStrictErr: makeTimeout(),
wantLaxErr: makeNxDomain(), // This one reaches the "test." FQDN.
},
{
desc: "searchY IPv4-only socket error fails in strict mode",
resolveWhich: func(quest *dnsQuestion) resolveWhichEnum {
if quest.Name == searchY && quest.Qtype == dnsTypeA {
return resolveOpError
}
return resolveOK
},
wantStrictErr: makeTempError("write: socket on fire"),
wantIPs: []string{ip6},
},
{
desc: "searchY IPv6-only timeout fails in strict mode",
resolveWhich: func(quest *dnsQuestion) resolveWhichEnum {
if quest.Name == searchY && quest.Qtype == dnsTypeAAAA {
return resolveTimeout
}
return resolveOK
},
wantStrictErr: makeTimeout(),
wantIPs: []string{ip4},
},
}
for i, tt := range cases {
fake := fakeDNSServer{func(_, s string, q *dnsMsg, deadline time.Time) (*dnsMsg, error) {
t.Log(s, q)
switch tt.resolveWhich(&q.question[0]) {
case resolveOK:
// Handle below.
case resolveOpError:
return nil, &OpError{Op: "write", Err: fmt.Errorf("socket on fire")}
case resolveServfail:
return &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
response: true,
rcode: dnsRcodeServerFailure,
},
question: q.question,
}, nil
case resolveTimeout:
return nil, poll.ErrTimeout
default:
t.Fatal("Impossible resolveWhich")
}
switch q.question[0].Name {
case searchX, name + ".":
// Return NXDOMAIN to utilize the search list.
return &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
response: true,
rcode: dnsRcodeNameError,
},
question: q.question,
}, nil
case searchY:
// Return records below.
default:
return nil, fmt.Errorf("Unexpected Name: %v", q.question[0].Name)
}
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
response: true,
},
question: q.question,
}
switch q.question[0].Qtype {
case dnsTypeA:
r.answer = []dnsRR{
&dnsRR_A{
Hdr: dnsRR_Header{
Name: q.question[0].Name,
Rrtype: dnsTypeA,
Class: dnsClassINET,
Rdlength: 4,
},
A: TestAddr,
},
}
case dnsTypeAAAA:
r.answer = []dnsRR{
&dnsRR_AAAA{
Hdr: dnsRR_Header{
Name: q.question[0].Name,
Rrtype: dnsTypeAAAA,
Class: dnsClassINET,
Rdlength: 16,
},
AAAA: TestAddr6,
},
}
default:
return nil, fmt.Errorf("Unexpected Qtype: %v", q.question[0].Qtype)
}
return r, nil
}}
for _, strict := range []bool{true, false} {
r := Resolver{PreferGo: true, StrictErrors: strict, Dial: fake.DialContext}
ips, err := r.LookupIPAddr(context.Background(), name)
var wantErr error
if strict {
wantErr = tt.wantStrictErr
} else {
wantErr = tt.wantLaxErr
}
if !reflect.DeepEqual(err, wantErr) {
t.Errorf("#%d (%s) strict=%v: got err %#v; want %#v", i, tt.desc, strict, err, wantErr)
}
gotIPs := map[string]struct{}{}
for _, ip := range ips {
gotIPs[ip.String()] = struct{}{}
}
wantIPs := map[string]struct{}{}
if wantErr == nil {
for _, ip := range tt.wantIPs {
wantIPs[ip] = struct{}{}
}
}
if !reflect.DeepEqual(gotIPs, wantIPs) {
t.Errorf("#%d (%s) strict=%v: got ips %v; want %v", i, tt.desc, strict, gotIPs, wantIPs)
}
}
}
}
// Issue 17448. With StrictErrors enabled, temporary errors should make
// LookupTXT stop walking the search list.
func TestStrictErrorsLookupTXT(t *testing.T) {
defer dnsWaitGroup.Wait()
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
}
defer conf.teardown()
confData := []string{
"nameserver 192.0.2.53",
"search x.golang.org y.golang.org",
}
if err := conf.writeAndUpdate(confData); err != nil {
t.Fatal(err)
}
const name = "test"
const server = "192.0.2.53:53"
const searchX = "test.x.golang.org."
const searchY = "test.y.golang.org."
const txt = "Hello World"
fake := fakeDNSServer{func(_, s string, q *dnsMsg, deadline time.Time) (*dnsMsg, error) {
t.Log(s, q)
switch q.question[0].Name {
case searchX:
return nil, poll.ErrTimeout
case searchY:
return mockTXTResponse(q), nil
default:
return nil, fmt.Errorf("Unexpected Name: %v", q.question[0].Name)
}
}}
for _, strict := range []bool{true, false} {
r := Resolver{StrictErrors: strict, Dial: fake.DialContext}
_, rrs, err := r.lookup(context.Background(), name, dnsTypeTXT)
var wantErr error
var wantRRs int
if strict {
wantErr = &DNSError{
Err: poll.ErrTimeout.Error(),
Name: name,
Server: server,
IsTimeout: true,
}
} else {
wantRRs = 1
}
if !reflect.DeepEqual(err, wantErr) {
t.Errorf("strict=%v: got err %#v; want %#v", strict, err, wantErr)
}
if len(rrs) != wantRRs {
t.Errorf("strict=%v: got %v; want %v", strict, len(rrs), wantRRs)
}
}
}
// Test for a race between uninstalling the test hooks and closing a
// socket connection. This used to fail when testing with -race.
func TestDNSGoroutineRace(t *testing.T) {
defer dnsWaitGroup.Wait()
fake := fakeDNSServer{func(n, s string, q *dnsMsg, t time.Time) (*dnsMsg, error) {
time.Sleep(10 * time.Microsecond)
return nil, poll.ErrTimeout
}}
r := Resolver{PreferGo: true, Dial: fake.DialContext}
// The timeout here is less than the timeout used by the server,
// so the goroutine started to query the (fake) server will hang
// around after this test is done if we don't call dnsWaitGroup.Wait.
ctx, cancel := context.WithTimeout(context.Background(), 2*time.Microsecond)
defer cancel()
_, err := r.LookupIPAddr(ctx, "where.are.they.now")
if err == nil {
t.Fatal("fake DNS lookup unexpectedly succeeded")
}
}