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tailscale/net/dns/resolver/tsdns_test.go
Adrian Dewhurst 8b11937eaf net/dns/resolver: permit larger max responses, signal truncation 
This raises the maximum DNS response message size from 512 to 4095. This
should be large enough for almost all situations that do not need TCP.
We still do not recognize EDNS, so we will still forward requests that
claim support for a larger response size than 4095 (that will be solved
later). For now, when a response comes back that is too large to fit in
our receive buffer, we now set the truncation flag in the DNS header,
which is an improvement from before but will prompt attempts to use TCP
which isn't supported yet.

On Windows, WSARecvFrom into a buffer that's too small returns an error
in addition to the data. On other OSes, the extra data is silently
discarded. In this case, we prefer the latter so need to catch the error
on Windows.

Partially addresses #1123

Signed-off-by: Adrian Dewhurst <adrian@tailscale.com>
2021-06-08 19:29:12 -04:00

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// Copyright (c) 2020 Tailscale Inc & 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 resolver
import (
"bytes"
"encoding/hex"
"errors"
"math/rand"
"net"
"testing"
dns "golang.org/x/net/dns/dnsmessage"
"inet.af/netaddr"
"tailscale.com/tstest"
"tailscale.com/util/dnsname"
)
var testipv4 = netaddr.MustParseIP("1.2.3.4")
var testipv6 = netaddr.MustParseIP("0001:0203:0405:0607:0809:0a0b:0c0d:0e0f")
var dnsCfg = Config{
Hosts: map[dnsname.FQDN][]netaddr.IP{
"test1.ipn.dev.": []netaddr.IP{testipv4},
"test2.ipn.dev.": []netaddr.IP{testipv6},
},
LocalDomains: []dnsname.FQDN{"ipn.dev."},
}
func dnspacket(domain dnsname.FQDN, tp dns.Type) []byte {
var dnsHeader dns.Header
question := dns.Question{
Name: dns.MustNewName(domain.WithTrailingDot()),
Type: tp,
Class: dns.ClassINET,
}
builder := dns.NewBuilder(nil, dnsHeader)
builder.StartQuestions()
builder.Question(question)
payload, _ := builder.Finish()
return payload
}
type dnsResponse struct {
ip netaddr.IP
txt []string
name dnsname.FQDN
rcode dns.RCode
truncated bool
}
func unpackResponse(payload []byte) (dnsResponse, error) {
var response dnsResponse
var parser dns.Parser
h, err := parser.Start(payload)
if err != nil {
return response, err
}
if !h.Response {
return response, errors.New("not a response")
}
response.rcode = h.RCode
if response.rcode != dns.RCodeSuccess {
return response, nil
}
response.truncated = h.Truncated
if response.truncated {
// TODO(#2067): Ideally, answer processing should still succeed when
// dealing with a truncated message, but currently when we truncate
// a packet, it's caused by the buffer being too small and usually that
// means the data runs out mid-record. dns.Parser does not like it when
// that happens. We can improve this by trimming off incomplete records.
return response, nil
}
err = parser.SkipAllQuestions()
if err != nil {
return response, err
}
ah, err := parser.AnswerHeader()
if err != nil {
return response, err
}
switch ah.Type {
case dns.TypeA:
res, err := parser.AResource()
if err != nil {
return response, err
}
response.ip = netaddr.IPv4(res.A[0], res.A[1], res.A[2], res.A[3])
case dns.TypeAAAA:
res, err := parser.AAAAResource()
if err != nil {
return response, err
}
response.ip = netaddr.IPv6Raw(res.AAAA)
case dns.TypeTXT:
res, err := parser.TXTResource()
if err != nil {
return response, err
}
response.txt = res.TXT
case dns.TypeNS:
res, err := parser.NSResource()
if err != nil {
return response, err
}
response.name, err = dnsname.ToFQDN(res.NS.String())
if err != nil {
return response, err
}
default:
return response, errors.New("type not in {A, AAAA, NS}")
}
return response, nil
}
func syncRespond(r *Resolver, query []byte) ([]byte, error) {
r.EnqueueRequest(query, netaddr.IPPort{})
payload, _, err := r.NextResponse()
return payload, err
}
func mustIP(str string) netaddr.IP {
ip, err := netaddr.ParseIP(str)
if err != nil {
panic(err)
}
return ip
}
func TestRDNSNameToIPv4(t *testing.T) {
tests := []struct {
name string
input dnsname.FQDN
wantIP netaddr.IP
wantOK bool
}{
{"valid", "4.123.24.1.in-addr.arpa.", netaddr.IPv4(1, 24, 123, 4), true},
{"double_dot", "1..2.3.in-addr.arpa.", netaddr.IP{}, false},
{"overflow", "1.256.3.4.in-addr.arpa.", netaddr.IP{}, false},
{"not_ip", "sub.do.ma.in.in-addr.arpa.", netaddr.IP{}, false},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
ip, ok := rdnsNameToIPv4(tt.input)
if ok != tt.wantOK {
t.Errorf("ok = %v; want %v", ok, tt.wantOK)
} else if ok && ip != tt.wantIP {
t.Errorf("ip = %v; want %v", ip, tt.wantIP)
}
})
}
}
func TestRDNSNameToIPv6(t *testing.T) {
tests := []struct {
name string
input dnsname.FQDN
wantIP netaddr.IP
wantOK bool
}{
{
"valid",
"b.a.9.8.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.",
mustIP("2001:db8::567:89ab"),
true,
},
{
"double_dot",
"b..9.8.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.",
netaddr.IP{},
false,
},
{
"double_hex",
"b.a.98.0.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.",
netaddr.IP{},
false,
},
{
"not_hex",
"b.a.g.0.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.",
netaddr.IP{},
false,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
ip, ok := rdnsNameToIPv6(tt.input)
if ok != tt.wantOK {
t.Errorf("ok = %v; want %v", ok, tt.wantOK)
} else if ok && ip != tt.wantIP {
t.Errorf("ip = %v; want %v", ip, tt.wantIP)
}
})
}
}
func TestResolveLocal(t *testing.T) {
r := New(t.Logf, nil)
defer r.Close()
r.SetConfig(dnsCfg)
tests := []struct {
name string
qname dnsname.FQDN
qtype dns.Type
ip netaddr.IP
code dns.RCode
}{
{"ipv4", "test1.ipn.dev.", dns.TypeA, testipv4, dns.RCodeSuccess},
{"ipv6", "test2.ipn.dev.", dns.TypeAAAA, testipv6, dns.RCodeSuccess},
{"no-ipv6", "test1.ipn.dev.", dns.TypeAAAA, netaddr.IP{}, dns.RCodeSuccess},
{"nxdomain", "test3.ipn.dev.", dns.TypeA, netaddr.IP{}, dns.RCodeNameError},
{"foreign domain", "google.com.", dns.TypeA, netaddr.IP{}, dns.RCodeRefused},
{"all", "test1.ipn.dev.", dns.TypeA, testipv4, dns.RCodeSuccess},
{"mx-ipv4", "test1.ipn.dev.", dns.TypeMX, netaddr.IP{}, dns.RCodeSuccess},
{"mx-ipv6", "test2.ipn.dev.", dns.TypeMX, netaddr.IP{}, dns.RCodeSuccess},
{"mx-nxdomain", "test3.ipn.dev.", dns.TypeMX, netaddr.IP{}, dns.RCodeNameError},
{"ns-nxdomain", "test3.ipn.dev.", dns.TypeNS, netaddr.IP{}, dns.RCodeNameError},
{"onion-domain", "footest.onion.", dns.TypeA, netaddr.IP{}, dns.RCodeNameError},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
ip, code := r.resolveLocal(tt.qname, tt.qtype)
if code != tt.code {
t.Errorf("code = %v; want %v", code, tt.code)
}
// Only check ip for non-err
if ip != tt.ip {
t.Errorf("ip = %v; want %v", ip, tt.ip)
}
})
}
}
func TestResolveLocalReverse(t *testing.T) {
r := New(t.Logf, nil)
defer r.Close()
r.SetConfig(dnsCfg)
tests := []struct {
name string
ip netaddr.IP
want dnsname.FQDN
code dns.RCode
}{
{"ipv4", testipv4, "test1.ipn.dev.", dns.RCodeSuccess},
{"ipv6", testipv6, "test2.ipn.dev.", dns.RCodeSuccess},
{"nxdomain", netaddr.IPv4(4, 3, 2, 1), "", dns.RCodeNameError},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
name, code := r.resolveLocalReverse(tt.ip)
if code != tt.code {
t.Errorf("code = %v; want %v", code, tt.code)
}
if name != tt.want {
t.Errorf("ip = %v; want %v", name, tt.want)
}
})
}
}
func ipv6Works() bool {
c, err := net.Listen("tcp", "[::1]:0")
if err != nil {
return false
}
c.Close()
return true
}
func generateTXT(size int, source rand.Source) []string {
const sizePerTXT = 120
if size%2 != 0 {
panic("even lengths only")
}
rng := rand.New(source)
txts := make([]string, 0, size/sizePerTXT+1)
raw := make([]byte, sizePerTXT/2)
rem := size
for ; rem > sizePerTXT; rem -= sizePerTXT {
rng.Read(raw)
txts = append(txts, hex.EncodeToString(raw))
}
if rem > 0 {
rng.Read(raw[:rem/2])
txts = append(txts, hex.EncodeToString(raw[:rem/2]))
}
return txts
}
func TestDelegate(t *testing.T) {
tstest.ResourceCheck(t)
if !ipv6Works() {
t.Skip("skipping test that requires localhost IPv6")
}
randSource := rand.NewSource(4)
// smallTXT does not require EDNS
smallTXT := generateTXT(300, randSource)
// medTXT and largeTXT are responses that require EDNS but we would like to
// support these sizes of response without truncation because they are
// moderately common.
medTXT := generateTXT(1200, randSource)
largeTXT := generateTXT(4000, randSource)
// xlargeTXT is slightly above the maximum response size that we support,
// so there should be truncation.
xlargeTXT := generateTXT(5000, randSource)
// hugeTXT is significantly larger than any typical MTU and will require
// significant fragmentation. For buffer management reasons, we do not
// intend to handle responses this large, so there should be truncation.
hugeTXT := generateTXT(64000, randSource)
v4server := serveDNS(t, "127.0.0.1:0",
"test.site.", resolveToIP(testipv4, testipv6, "dns.test.site."),
"nxdomain.site.", resolveToNXDOMAIN,
"small.txt.", resolveToTXT(smallTXT),
"med.txt.", resolveToTXT(medTXT),
"large.txt.", resolveToTXT(largeTXT),
"xlarge.txt.", resolveToTXT(xlargeTXT),
"huge.txt.", resolveToTXT(hugeTXT))
defer v4server.Shutdown()
v6server := serveDNS(t, "[::1]:0",
"test.site.", resolveToIP(testipv4, testipv6, "dns.test.site."),
"nxdomain.site.", resolveToNXDOMAIN,
"small.txt.", resolveToTXT(smallTXT),
"med.txt.", resolveToTXT(medTXT),
"large.txt.", resolveToTXT(largeTXT),
"xlarge.txt.", resolveToTXT(xlargeTXT),
"huge.txt.", resolveToTXT(hugeTXT))
defer v6server.Shutdown()
r := New(t.Logf, nil)
defer r.Close()
cfg := dnsCfg
cfg.Routes = map[dnsname.FQDN][]netaddr.IPPort{
".": {
netaddr.MustParseIPPort(v4server.PacketConn.LocalAddr().String()),
netaddr.MustParseIPPort(v6server.PacketConn.LocalAddr().String()),
},
}
r.SetConfig(cfg)
tests := []struct {
title string
query []byte
response dnsResponse
}{
{
"ipv4",
dnspacket("test.site.", dns.TypeA),
dnsResponse{ip: testipv4, rcode: dns.RCodeSuccess},
},
{
"ipv6",
dnspacket("test.site.", dns.TypeAAAA),
dnsResponse{ip: testipv6, rcode: dns.RCodeSuccess},
},
{
"ns",
dnspacket("test.site.", dns.TypeNS),
dnsResponse{name: "dns.test.site.", rcode: dns.RCodeSuccess},
},
{
"nxdomain",
dnspacket("nxdomain.site.", dns.TypeA),
dnsResponse{rcode: dns.RCodeNameError},
},
{
"smalltxt",
dnspacket("small.txt.", dns.TypeTXT),
dnsResponse{txt: smallTXT, rcode: dns.RCodeSuccess},
},
{
"medtxt",
dnspacket("med.txt.", dns.TypeTXT),
dnsResponse{txt: medTXT, rcode: dns.RCodeSuccess},
},
{
"largetxt",
dnspacket("large.txt.", dns.TypeTXT),
dnsResponse{txt: largeTXT, rcode: dns.RCodeSuccess},
},
{
"xlargetxt",
dnspacket("xlarge.txt.", dns.TypeTXT),
dnsResponse{rcode: dns.RCodeSuccess, truncated: true},
},
{
"hugetxt",
dnspacket("huge.txt.", dns.TypeTXT),
dnsResponse{rcode: dns.RCodeSuccess, truncated: true},
},
}
for _, tt := range tests {
t.Run(tt.title, func(t *testing.T) {
payload, err := syncRespond(r, tt.query)
if err != nil {
t.Errorf("err = %v; want nil", err)
return
}
response, err := unpackResponse(payload)
if err != nil {
t.Errorf("extract: err = %v; want nil (in %x)", err, payload)
return
}
if response.rcode != tt.response.rcode {
t.Errorf("rcode = %v; want %v", response.rcode, tt.response.rcode)
}
if response.ip != tt.response.ip {
t.Errorf("ip = %v; want %v", response.ip, tt.response.ip)
}
if response.name != tt.response.name {
t.Errorf("name = %v; want %v", response.name, tt.response.name)
}
if len(response.txt) != len(tt.response.txt) {
t.Errorf("%v txt records, want %v txt records", len(response.txt), len(tt.response.txt))
} else {
for i := range response.txt {
if response.txt[i] != tt.response.txt[i] {
t.Errorf("txt record %v is %s, want %s", i, response.txt[i], tt.response.txt[i])
}
}
}
})
}
}
func TestDelegateSplitRoute(t *testing.T) {
test4 := netaddr.MustParseIP("2.3.4.5")
test6 := netaddr.MustParseIP("ff::1")
server1 := serveDNS(t, "127.0.0.1:0",
"test.site.", resolveToIP(testipv4, testipv6, "dns.test.site."))
defer server1.Shutdown()
server2 := serveDNS(t, "127.0.0.1:0",
"test.other.", resolveToIP(test4, test6, "dns.other."))
defer server2.Shutdown()
r := New(t.Logf, nil)
defer r.Close()
cfg := dnsCfg
cfg.Routes = map[dnsname.FQDN][]netaddr.IPPort{
".": {netaddr.MustParseIPPort(server1.PacketConn.LocalAddr().String())},
"other.": {netaddr.MustParseIPPort(server2.PacketConn.LocalAddr().String())},
}
r.SetConfig(cfg)
tests := []struct {
title string
query []byte
response dnsResponse
}{
{
"general",
dnspacket("test.site.", dns.TypeA),
dnsResponse{ip: testipv4, rcode: dns.RCodeSuccess},
},
{
"override",
dnspacket("test.other.", dns.TypeA),
dnsResponse{ip: test4, rcode: dns.RCodeSuccess},
},
}
for _, tt := range tests {
t.Run(tt.title, func(t *testing.T) {
payload, err := syncRespond(r, tt.query)
if err != nil {
t.Errorf("err = %v; want nil", err)
return
}
response, err := unpackResponse(payload)
if err != nil {
t.Errorf("extract: err = %v; want nil (in %x)", err, payload)
return
}
if response.rcode != tt.response.rcode {
t.Errorf("rcode = %v; want %v", response.rcode, tt.response.rcode)
}
if response.ip != tt.response.ip {
t.Errorf("ip = %v; want %v", response.ip, tt.response.ip)
}
if response.name != tt.response.name {
t.Errorf("name = %v; want %v", response.name, tt.response.name)
}
})
}
}
func TestDelegateCollision(t *testing.T) {
server := serveDNS(t, "127.0.0.1:0",
"test.site.", resolveToIP(testipv4, testipv6, "dns.test.site."))
defer server.Shutdown()
r := New(t.Logf, nil)
defer r.Close()
cfg := dnsCfg
cfg.Routes = map[dnsname.FQDN][]netaddr.IPPort{
".": {
netaddr.MustParseIPPort(server.PacketConn.LocalAddr().String()),
},
}
r.SetConfig(cfg)
packets := []struct {
qname dnsname.FQDN
qtype dns.Type
addr netaddr.IPPort
}{
{"test.site.", dns.TypeA, netaddr.IPPortFrom(netaddr.IPv4(1, 1, 1, 1), 1001)},
{"test.site.", dns.TypeAAAA, netaddr.IPPortFrom(netaddr.IPv4(1, 1, 1, 1), 1002)},
}
// packets will have the same dns txid.
for _, p := range packets {
payload := dnspacket(p.qname, p.qtype)
err := r.EnqueueRequest(payload, p.addr)
if err != nil {
t.Error(err)
}
}
// Despite the txid collision, the answer(s) should still match the query.
resp, addr, err := r.NextResponse()
if err != nil {
t.Error(err)
}
var p dns.Parser
_, err = p.Start(resp)
if err != nil {
t.Error(err)
}
err = p.SkipAllQuestions()
if err != nil {
t.Error(err)
}
ans, err := p.AllAnswers()
if err != nil {
t.Error(err)
}
var wantType dns.Type
switch ans[0].Body.(type) {
case *dns.AResource:
wantType = dns.TypeA
case *dns.AAAAResource:
wantType = dns.TypeAAAA
default:
t.Errorf("unexpected answer type: %T", ans[0].Body)
}
for _, p := range packets {
if p.qtype == wantType && p.addr != addr {
t.Errorf("addr = %v; want %v", addr, p.addr)
}
}
}
var allResponse = []byte{
0x00, 0x00, // transaction id: 0
0x84, 0x00, // flags: response, authoritative, no error
0x00, 0x01, // one question
0x00, 0x01, // one answer
0x00, 0x00, 0x00, 0x00, // no authority or additional RRs
// Question:
0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name
0x00, 0xff, 0x00, 0x01, // type ALL, class IN
// Answer:
0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name
0x00, 0x01, 0x00, 0x01, // type A, class IN
0x00, 0x00, 0x02, 0x58, // TTL: 600
0x00, 0x04, // length: 4 bytes
0x01, 0x02, 0x03, 0x04, // A: 1.2.3.4
}
var ipv4Response = []byte{
0x00, 0x00, // transaction id: 0
0x84, 0x00, // flags: response, authoritative, no error
0x00, 0x01, // one question
0x00, 0x01, // one answer
0x00, 0x00, 0x00, 0x00, // no authority or additional RRs
// Question:
0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name
0x00, 0x01, 0x00, 0x01, // type A, class IN
// Answer:
0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name
0x00, 0x01, 0x00, 0x01, // type A, class IN
0x00, 0x00, 0x02, 0x58, // TTL: 600
0x00, 0x04, // length: 4 bytes
0x01, 0x02, 0x03, 0x04, // A: 1.2.3.4
}
var ipv6Response = []byte{
0x00, 0x00, // transaction id: 0
0x84, 0x00, // flags: response, authoritative, no error
0x00, 0x01, // one question
0x00, 0x01, // one answer
0x00, 0x00, 0x00, 0x00, // no authority or additional RRs
// Question:
0x05, 0x74, 0x65, 0x73, 0x74, 0x32, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name
0x00, 0x1c, 0x00, 0x01, // type AAAA, class IN
// Answer:
0x05, 0x74, 0x65, 0x73, 0x74, 0x32, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name
0x00, 0x1c, 0x00, 0x01, // type AAAA, class IN
0x00, 0x00, 0x02, 0x58, // TTL: 600
0x00, 0x10, // length: 16 bytes
// AAAA: 0001:0203:0405:0607:0809:0A0B:0C0D:0E0F
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0xb, 0xc, 0xd, 0xe, 0xf,
}
var ipv4UppercaseResponse = []byte{
0x00, 0x00, // transaction id: 0
0x84, 0x00, // flags: response, authoritative, no error
0x00, 0x01, // one question
0x00, 0x01, // one answer
0x00, 0x00, 0x00, 0x00, // no authority or additional RRs
// Question:
0x05, 0x54, 0x45, 0x53, 0x54, 0x31, 0x03, 0x49, 0x50, 0x4e, 0x03, 0x44, 0x45, 0x56, 0x00, // name
0x00, 0x01, 0x00, 0x01, // type A, class IN
// Answer:
0x05, 0x54, 0x45, 0x53, 0x54, 0x31, 0x03, 0x49, 0x50, 0x4e, 0x03, 0x44, 0x45, 0x56, 0x00, // name
0x00, 0x01, 0x00, 0x01, // type A, class IN
0x00, 0x00, 0x02, 0x58, // TTL: 600
0x00, 0x04, // length: 4 bytes
0x01, 0x02, 0x03, 0x04, // A: 1.2.3.4
}
var ptrResponse = []byte{
0x00, 0x00, // transaction id: 0
0x84, 0x00, // flags: response, authoritative, no error
0x00, 0x01, // one question
0x00, 0x01, // one answer
0x00, 0x00, 0x00, 0x00, // no authority or additional RRs
// Question: 4.3.2.1.in-addr.arpa
0x01, 0x34, 0x01, 0x33, 0x01, 0x32, 0x01, 0x31, 0x07,
0x69, 0x6e, 0x2d, 0x61, 0x64, 0x64, 0x72, 0x04, 0x61, 0x72, 0x70, 0x61, 0x00,
0x00, 0x0c, 0x00, 0x01, // type PTR, class IN
// Answer: 4.3.2.1.in-addr.arpa
0x01, 0x34, 0x01, 0x33, 0x01, 0x32, 0x01, 0x31, 0x07,
0x69, 0x6e, 0x2d, 0x61, 0x64, 0x64, 0x72, 0x04, 0x61, 0x72, 0x70, 0x61, 0x00,
0x00, 0x0c, 0x00, 0x01, // type PTR, class IN
0x00, 0x00, 0x02, 0x58, // TTL: 600
0x00, 0x0f, // length: 15 bytes
// PTR: test1.ipn.dev
0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00,
}
var ptrResponse6 = []byte{
0x00, 0x00, // transaction id: 0
0x84, 0x00, // flags: response, authoritative, no error
0x00, 0x01, // one question
0x00, 0x01, // one answer
0x00, 0x00, 0x00, 0x00, // no authority or additional RRs
// Question: f.0.e.0.d.0.c.0.b.0.a.0.9.0.8.0.7.0.6.0.5.0.4.0.3.0.2.0.1.0.0.0.ip6.arpa
0x01, 0x66, 0x01, 0x30, 0x01, 0x65, 0x01, 0x30,
0x01, 0x64, 0x01, 0x30, 0x01, 0x63, 0x01, 0x30,
0x01, 0x62, 0x01, 0x30, 0x01, 0x61, 0x01, 0x30,
0x01, 0x39, 0x01, 0x30, 0x01, 0x38, 0x01, 0x30,
0x01, 0x37, 0x01, 0x30, 0x01, 0x36, 0x01, 0x30,
0x01, 0x35, 0x01, 0x30, 0x01, 0x34, 0x01, 0x30,
0x01, 0x33, 0x01, 0x30, 0x01, 0x32, 0x01, 0x30,
0x01, 0x31, 0x01, 0x30, 0x01, 0x30, 0x01, 0x30,
0x03, 0x69, 0x70, 0x36,
0x04, 0x61, 0x72, 0x70, 0x61, 0x00,
0x00, 0x0c, 0x00, 0x01, // type PTR, class IN6
// Answer: f.0.e.0.d.0.c.0.b.0.a.0.9.0.8.0.7.0.6.0.5.0.4.0.3.0.2.0.1.0.0.0.ip6.arpa
0x01, 0x66, 0x01, 0x30, 0x01, 0x65, 0x01, 0x30,
0x01, 0x64, 0x01, 0x30, 0x01, 0x63, 0x01, 0x30,
0x01, 0x62, 0x01, 0x30, 0x01, 0x61, 0x01, 0x30,
0x01, 0x39, 0x01, 0x30, 0x01, 0x38, 0x01, 0x30,
0x01, 0x37, 0x01, 0x30, 0x01, 0x36, 0x01, 0x30,
0x01, 0x35, 0x01, 0x30, 0x01, 0x34, 0x01, 0x30,
0x01, 0x33, 0x01, 0x30, 0x01, 0x32, 0x01, 0x30,
0x01, 0x31, 0x01, 0x30, 0x01, 0x30, 0x01, 0x30,
0x03, 0x69, 0x70, 0x36,
0x04, 0x61, 0x72, 0x70, 0x61, 0x00,
0x00, 0x0c, 0x00, 0x01, // type PTR, class IN
0x00, 0x00, 0x02, 0x58, // TTL: 600
0x00, 0x0f, // length: 15 bytes
// PTR: test2.ipn.dev
0x05, 0x74, 0x65, 0x73, 0x74, 0x32, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00,
}
var nxdomainResponse = []byte{
0x00, 0x00, // transaction id: 0
0x84, 0x03, // flags: response, authoritative, error: nxdomain
0x00, 0x01, // one question
0x00, 0x00, // no answers
0x00, 0x00, 0x00, 0x00, // no authority or additional RRs
// Question:
0x05, 0x74, 0x65, 0x73, 0x74, 0x33, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name
0x00, 0x01, 0x00, 0x01, // type A, class IN
}
var emptyResponse = []byte{
0x00, 0x00, // transaction id: 0
0x84, 0x00, // flags: response, authoritative, no error
0x00, 0x01, // one question
0x00, 0x00, // no answers
0x00, 0x00, 0x00, 0x00, // no authority or additional RRs
// Question:
0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name
0x00, 0x1c, 0x00, 0x01, // type AAAA, class IN
}
func TestFull(t *testing.T) {
r := New(t.Logf, nil)
defer r.Close()
r.SetConfig(dnsCfg)
// One full packet and one error packet
tests := []struct {
name string
request []byte
response []byte
}{
{"all", dnspacket("test1.ipn.dev.", dns.TypeALL), allResponse},
{"ipv4", dnspacket("test1.ipn.dev.", dns.TypeA), ipv4Response},
{"ipv6", dnspacket("test2.ipn.dev.", dns.TypeAAAA), ipv6Response},
{"no-ipv6", dnspacket("test1.ipn.dev.", dns.TypeAAAA), emptyResponse},
{"upper", dnspacket("TEST1.IPN.DEV.", dns.TypeA), ipv4UppercaseResponse},
{"ptr4", dnspacket("4.3.2.1.in-addr.arpa.", dns.TypePTR), ptrResponse},
{"ptr6", dnspacket("f.0.e.0.d.0.c.0.b.0.a.0.9.0.8.0.7.0.6.0.5.0.4.0.3.0.2.0.1.0.0.0.ip6.arpa.",
dns.TypePTR), ptrResponse6},
{"nxdomain", dnspacket("test3.ipn.dev.", dns.TypeA), nxdomainResponse},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
response, err := syncRespond(r, tt.request)
if err != nil {
t.Errorf("err = %v; want nil", err)
}
if !bytes.Equal(response, tt.response) {
t.Errorf("response = %x; want %x", response, tt.response)
}
})
}
}
func TestAllocs(t *testing.T) {
r := New(t.Logf, nil)
defer r.Close()
r.SetConfig(dnsCfg)
// It is seemingly pointless to test allocs in the delegate path,
// as dialer.Dial -> Read -> Write alone comprise 12 allocs.
tests := []struct {
name string
query []byte
want int
}{
// Name lowercasing and response slice created by dns.NewBuilder.
{"forward", dnspacket("test1.ipn.dev.", dns.TypeA), 2},
// 3 extra allocs in rdnsNameToIPv4 and one in marshalPTRRecord (dns.NewName).
{"reverse", dnspacket("4.3.2.1.in-addr.arpa.", dns.TypePTR), 5},
}
for _, tt := range tests {
allocs := testing.AllocsPerRun(100, func() {
syncRespond(r, tt.query)
})
if int(allocs) > tt.want {
t.Errorf("%s: allocs = %v; want %v", tt.name, allocs, tt.want)
}
}
}
func TestTrimRDNSBonjourPrefix(t *testing.T) {
tests := []struct {
in dnsname.FQDN
want bool
}{
{"b._dns-sd._udp.0.10.20.172.in-addr.arpa.", true},
{"db._dns-sd._udp.0.10.20.172.in-addr.arpa.", true},
{"r._dns-sd._udp.0.10.20.172.in-addr.arpa.", true},
{"dr._dns-sd._udp.0.10.20.172.in-addr.arpa.", true},
{"lb._dns-sd._udp.0.10.20.172.in-addr.arpa.", true},
{"qq._dns-sd._udp.0.10.20.172.in-addr.arpa.", false},
{"0.10.20.172.in-addr.arpa.", false},
}
for _, test := range tests {
got := hasRDNSBonjourPrefix(test.in)
if got != test.want {
t.Errorf("trimRDNSBonjourPrefix(%q) = %v, want %v", test.in, got, test.want)
}
}
}
func BenchmarkFull(b *testing.B) {
server := serveDNS(b, "127.0.0.1:0",
"test.site.", resolveToIP(testipv4, testipv6, "dns.test.site."))
defer server.Shutdown()
r := New(b.Logf, nil)
defer r.Close()
cfg := dnsCfg
cfg.Routes = map[dnsname.FQDN][]netaddr.IPPort{
".": {
netaddr.MustParseIPPort(server.PacketConn.LocalAddr().String()),
},
}
tests := []struct {
name string
request []byte
}{
{"forward", dnspacket("test1.ipn.dev.", dns.TypeA)},
{"reverse", dnspacket("4.3.2.1.in-addr.arpa.", dns.TypePTR)},
{"delegated", dnspacket("test.site.", dns.TypeA)},
}
for _, tt := range tests {
b.Run(tt.name, func(b *testing.B) {
for i := 0; i < b.N; i++ {
syncRespond(r, tt.request)
}
})
}
}
func TestMarshalResponseFormatError(t *testing.T) {
resp := new(response)
resp.Header.RCode = dns.RCodeFormatError
v, err := marshalResponse(resp)
if err != nil {
t.Errorf("marshal error: %v", err)
}
t.Logf("response: %q", v)
}
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