net/dns/resolver: add Windows ExitDNS service support, using net package

Updates #1713
Updates #835

Change-Id: Ia71e96d0632c2d617b401695ad68301b07c1c2ec
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
pull/3553/head
Brad Fitzpatrick 3 years ago committed by Brad Fitzpatrick
parent cab5c46481
commit cced414c7d

@ -1797,10 +1797,9 @@ func (b *LocalBackend) peerAPIServicesLocked() (ret []tailcfg.Service) {
})
}
switch runtime.GOOS {
case "linux", "freebsd", "openbsd", "illumos", "darwin":
case "linux", "freebsd", "openbsd", "illumos", "darwin", "windows":
// These are the platforms currently supported by
// net/dns/resolver/tsdns.go:Resolver.HandleExitNodeDNSQuery.
// TODO(bradfitz): add windows once it's done there.
ret = append(ret, tailcfg.Service{
Proto: tailcfg.PeerAPIDNS,
Port: 1, // version

@ -360,7 +360,8 @@ func (r *Resolver) HandleExitNodeDNSQuery(ctx context.Context, q []byte, from ne
case "windows":
// TODO: use DnsQueryEx and write to ch.
// See https://docs.microsoft.com/en-us/windows/win32/api/windns/nf-windns-dnsqueryex.
return nil, errors.New("TODO: windows exit node suport")
// For now just use the net package:
return handleExitNodeDNSQueryWithNetPkg(ctx, nil, resp)
case "darwin":
// /etc/resolv.conf is a lie and only says one upstream DNS
// but for now that's probably good enough. Later we'll
@ -404,6 +405,106 @@ func (r *Resolver) HandleExitNodeDNSQuery(ctx context.Context, q []byte, from ne
}
}
// handleExitNodeDNSQueryWithNetPkg takes a DNS query message in q and
// return a reply (for the ExitDNS DoH service) using the net package's
// native APIs. This is only used on Windows for now.
//
// If resolver is nil, the net.Resolver zero value is used.
//
// response contains the pre-serialized response, which notably
// includes the original question and its header.
func handleExitNodeDNSQueryWithNetPkg(ctx context.Context, resolver *net.Resolver, resp *response) (res []byte, err error) {
if resp.Question.Class != dns.ClassINET {
return nil, errors.New("unsupported class")
}
r := resolver
if r == nil {
r = new(net.Resolver)
}
name := resp.Question.Name.String()
handleError := func(err error) (res []byte, _ error) {
if isGoNoSuchHostError(err) {
resp.Header.RCode = dns.RCodeNameError
return marshalResponse(resp)
}
// TODO: map other errors to RCodeServerFailure?
// Or I guess our caller should do that?
return nil, err
}
resp.Header.RCode = dns.RCodeSuccess // unless changed below
switch resp.Question.Type {
case dns.TypeA, dns.TypeAAAA:
network := "ip4"
if resp.Question.Type == dns.TypeAAAA {
network = "ip6"
}
ips, err := r.LookupIP(ctx, network, name)
if err != nil {
return handleError(err)
}
for _, stdIP := range ips {
if ip, ok := netaddr.FromStdIP(stdIP); ok {
resp.IPs = append(resp.IPs, ip)
}
}
case dns.TypeTXT:
strs, err := r.LookupTXT(ctx, name)
if err != nil {
return handleError(err)
}
resp.TXT = strs
case dns.TypePTR:
ipStr, ok := unARPA(name)
if !ok {
// TODO: is this RCodeFormatError?
return nil, errors.New("bogus PTR name")
}
addrs, err := r.LookupAddr(ctx, ipStr)
if err != nil {
return handleError(err)
}
if len(addrs) > 0 {
resp.Name, _ = dnsname.ToFQDN(addrs[0])
}
case dns.TypeCNAME:
cname, err := r.LookupCNAME(ctx, name)
if err != nil {
return handleError(err)
}
resp.CNAME = cname
case dns.TypeSRV:
// Thanks, Go: "To accommodate services publishing SRV
// records under non-standard names, if both service
// and proto are empty strings, LookupSRV looks up
// name directly."
_, srvs, err := r.LookupSRV(ctx, "", "", name)
if err != nil {
return handleError(err)
}
resp.SRVs = srvs
case dns.TypeNS:
nss, err := r.LookupNS(ctx, name)
if err != nil {
return handleError(err)
}
resp.NSs = nss
default:
return nil, fmt.Errorf("unsupported record type %v", resp.Question.Type)
}
return marshalResponse(resp)
}
func isGoNoSuchHostError(err error) bool {
if de, ok := err.(*net.DNSError); ok {
return de.IsNotFound
}
return false
}
type resolvConfCache struct {
mod time.Time
size int64
@ -604,10 +705,27 @@ func (r *Resolver) handleQuery(pkt packet) {
type response struct {
Header dns.Header
Question dns.Question
// Name is the response to a PTR query.
Name dnsname.FQDN
// IP is the response to an A, AAAA, or ALL query.
IP netaddr.IP
// IP and IPs are the responses to an A, AAAA, or ALL query.
// Either/both/neither can be populated.
IP netaddr.IP
IPs []netaddr.IP
// TXT is the response to a TXT query.
// Each one is its own RR with one string.
TXT []string
// CNAME is the response to a CNAME query.
CNAME string
// SRVs are the responses to a SRV query.
SRVs []*net.SRV
// NSs are the responses to an NS query.
NSs []*net.NS
}
var dnsParserPool = &sync.Pool{
@ -683,6 +801,16 @@ func marshalAAAARecord(name dns.Name, ip netaddr.IP, builder *dns.Builder) error
return builder.AAAAResource(answerHeader, answer)
}
func marshalIP(name dns.Name, ip netaddr.IP, builder *dns.Builder) error {
if ip.Is4() {
return marshalARecord(name, ip, builder)
}
if ip.Is6() {
return marshalAAAARecord(name, ip, builder)
}
return nil
}
// marshalPTRRecord serializes a PTR record into an active builder.
// The caller may continue using the builder following the call.
func marshalPTRRecord(queryName dns.Name, name dnsname.FQDN, builder *dns.Builder) error {
@ -702,6 +830,83 @@ func marshalPTRRecord(queryName dns.Name, name dnsname.FQDN, builder *dns.Builde
return builder.PTRResource(answerHeader, answer)
}
func marshalTXT(queryName dns.Name, txts []string, builder *dns.Builder) error {
for _, txt := range txts {
if err := builder.TXTResource(dns.ResourceHeader{
Name: queryName,
Type: dns.TypeTXT,
Class: dns.ClassINET,
TTL: uint32(defaultTTL / time.Second),
}, dns.TXTResource{
TXT: []string{txt},
}); err != nil {
return err
}
}
return nil
}
func marshalCNAME(queryName dns.Name, cname string, builder *dns.Builder) error {
if cname == "" {
return nil
}
name, err := dns.NewName(cname)
if err != nil {
return err
}
return builder.CNAMEResource(dns.ResourceHeader{
Name: queryName,
Type: dns.TypeCNAME,
Class: dns.ClassINET,
TTL: uint32(defaultTTL / time.Second),
}, dns.CNAMEResource{
CNAME: name,
})
}
func marshalNS(queryName dns.Name, nss []*net.NS, builder *dns.Builder) error {
for _, ns := range nss {
name, err := dns.NewName(ns.Host)
if err != nil {
return err
}
err = builder.NSResource(dns.ResourceHeader{
Name: queryName,
Type: dns.TypeNS,
Class: dns.ClassINET,
TTL: uint32(defaultTTL / time.Second),
}, dns.NSResource{NS: name})
if err != nil {
return err
}
}
return nil
}
func marshalSRV(queryName dns.Name, srvs []*net.SRV, builder *dns.Builder) error {
for _, s := range srvs {
srvName, err := dns.NewName(s.Target)
if err != nil {
return err
}
err = builder.SRVResource(dns.ResourceHeader{
Name: queryName,
Type: dns.TypeSRV,
Class: dns.ClassINET,
TTL: uint32(defaultTTL / time.Second),
}, dns.SRVResource{
Target: srvName,
Priority: s.Priority,
Port: s.Port,
Weight: s.Weight,
})
if err != nil {
return err
}
}
return nil
}
// marshalResponse serializes the DNS response into a new buffer.
func marshalResponse(resp *response) ([]byte, error) {
resp.Header.Response = true
@ -712,6 +917,14 @@ func marshalResponse(resp *response) ([]byte, error) {
builder := dns.NewBuilder(nil, resp.Header)
// TODO(bradfitz): I'm not sure why this wasn't enabled
// before, but for now (2021-12-09) enable it at least when
// there's more than 1 record (which was never the case
// before), where it really helps.
if len(resp.IPs) > 1 {
builder.EnableCompression()
}
isSuccess := resp.Header.RCode == dns.RCodeSuccess
if resp.Question.Type != 0 || isSuccess {
@ -738,13 +951,24 @@ func marshalResponse(resp *response) ([]byte, error) {
switch resp.Question.Type {
case dns.TypeA, dns.TypeAAAA, dns.TypeALL:
if resp.IP.Is4() {
err = marshalARecord(resp.Question.Name, resp.IP, &builder)
} else if resp.IP.Is6() {
err = marshalAAAARecord(resp.Question.Name, resp.IP, &builder)
if err := marshalIP(resp.Question.Name, resp.IP, &builder); err != nil {
return nil, err
}
for _, ip := range resp.IPs {
if err := marshalIP(resp.Question.Name, ip, &builder); err != nil {
return nil, err
}
}
case dns.TypePTR:
err = marshalPTRRecord(resp.Question.Name, resp.Name, &builder)
case dns.TypeTXT:
err = marshalTXT(resp.Question.Name, resp.TXT, &builder)
case dns.TypeCNAME:
err = marshalCNAME(resp.Question.Name, resp.CNAME, &builder)
case dns.TypeSRV:
err = marshalSRV(resp.Question.Name, resp.SRVs, &builder)
case dns.TypeNS:
err = marshalNS(resp.Question.Name, resp.NSs, &builder)
}
if err != nil {
return nil, err
@ -926,6 +1150,37 @@ func (r *Resolver) respond(query []byte) ([]byte, error) {
return marshalResponse(resp)
}
// unARPA maps from "4.4.8.8.in-addr.arpa." to "8.8.4.4", etc.
func unARPA(a string) (ipStr string, ok bool) {
const suf4 = ".in-addr.arpa."
if strings.HasSuffix(a, suf4) {
s := strings.TrimSuffix(a, suf4)
// Parse and reverse octets.
ip, err := netaddr.ParseIP(s)
if err != nil || !ip.Is4() {
return "", false
}
a4 := ip.As4()
return netaddr.IPv4(a4[3], a4[2], a4[1], a4[0]).String(), true
}
const suf6 = ".ip6.arpa."
if len(a) == len("e.0.0.2.0.0.0.0.0.0.0.0.0.0.0.0.b.0.8.0.a.0.0.4.0.b.8.f.7.0.6.2.ip6.arpa.") &&
strings.HasSuffix(a, suf6) {
var hx [32]byte
var a16 [16]byte
for i := range hx {
hx[31-i] = a[i*2]
if a[i*2+1] != '.' {
return "", false
}
}
hex.Decode(a16[:], hx[:])
return netaddr.IPFrom16(a16).String(), true
}
return "", false
}
var (
metricDNSQueryLocal = clientmetric.NewCounter("dns_query_local")
metricDNSQueryErrorClosed = clientmetric.NewCounter("dns_query_local_error_closed")

@ -6,6 +6,7 @@ package resolver
import (
"fmt"
"net"
"strings"
"testing"
@ -179,6 +180,129 @@ var resolveToNXDOMAIN = dns.HandlerFunc(func(w dns.ResponseWriter, req *dns.Msg)
w.WriteMsg(m)
})
// weirdoGoCNAMEHandler returns a DNS handler that satisfies
// Go's weird Resolver.LookupCNAME (read its godoc carefully!).
//
// This doesn't even return a CNAME record, because that's not
// what Go looks for.
func weirdoGoCNAMEHandler(target string) dns.HandlerFunc {
return func(w dns.ResponseWriter, req *dns.Msg) {
m := new(dns.Msg)
m.SetReply(req)
question := req.Question[0]
switch question.Qtype {
case dns.TypeA:
m.Answer = append(m.Answer, &dns.CNAME{
Hdr: dns.RR_Header{
Name: target,
Rrtype: dns.TypeCNAME,
Class: dns.ClassINET,
Ttl: 600,
},
Target: target,
})
case dns.TypeAAAA:
m.Answer = append(m.Answer, &dns.AAAA{
Hdr: dns.RR_Header{
Name: target,
Rrtype: dns.TypeAAAA,
Class: dns.ClassINET,
Ttl: 600,
},
AAAA: net.ParseIP("1::2"),
})
}
w.WriteMsg(m)
}
}
// dnsHandler returns a handler that replies with the answers/options
// provided.
//
// Types supported: netaddr.IP.
func dnsHandler(answers ...interface{}) dns.HandlerFunc {
return func(w dns.ResponseWriter, req *dns.Msg) {
m := new(dns.Msg)
m.SetReply(req)
if len(req.Question) != 1 {
panic("not a single-question request")
}
m.RecursionAvailable = true // to stop net package's errLameReferral on empty replies
question := req.Question[0]
for _, a := range answers {
switch a := a.(type) {
default:
panic(fmt.Sprintf("unsupported dnsHandler arg %T", a))
case netaddr.IP:
ip := a
if ip.Is4() {
m.Answer = append(m.Answer, &dns.A{
Hdr: dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
},
A: ip.IPAddr().IP,
})
} else if ip.Is6() {
m.Answer = append(m.Answer, &dns.AAAA{
Hdr: dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeAAAA,
Class: dns.ClassINET,
},
AAAA: ip.IPAddr().IP,
})
}
case dns.PTR:
ptr := a
ptr.Hdr = dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypePTR,
Class: dns.ClassINET,
}
m.Answer = append(m.Answer, &ptr)
case dns.CNAME:
c := a
c.Hdr = dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeCNAME,
Class: dns.ClassINET,
Ttl: 600,
}
m.Answer = append(m.Answer, &c)
case dns.TXT:
txt := a
txt.Hdr = dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeTXT,
Class: dns.ClassINET,
}
m.Answer = append(m.Answer, &txt)
case dns.SRV:
srv := a
srv.Hdr = dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeSRV,
Class: dns.ClassINET,
}
m.Answer = append(m.Answer, &srv)
case dns.NS:
rr := a
rr.Hdr = dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeNS,
Class: dns.ClassINET,
}
m.Answer = append(m.Answer, &rr)
}
}
w.WriteMsg(m)
}
}
func serveDNS(tb testing.TB, addr string, records ...interface{}) *dns.Server {
if len(records)%2 != 0 {
panic("must have an even number of record values")

@ -6,16 +6,22 @@ package resolver
import (
"bytes"
"context"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
"math/rand"
"net"
"reflect"
"runtime"
"strconv"
"strings"
"testing"
"time"
miekdns "github.com/miekg/dns"
"golang.org/x/net/dns/dnsmessage"
dns "golang.org/x/net/dns/dnsmessage"
"inet.af/netaddr"
"tailscale.com/net/tsdial"
@ -43,6 +49,8 @@ var dnsCfg = Config{
const noEdns = 0
const dnsHeaderLen = 12
func dnspacket(domain dnsname.FQDN, tp dns.Type, ednsSize uint16) []byte {
var dnsHeader dns.Header
question := dns.Question{
@ -1093,3 +1101,383 @@ func TestForwardLinkSelection(t *testing.T) {
type linkSelFunc func(ip netaddr.IP) string
func (f linkSelFunc) PickLink(ip netaddr.IP) string { return f(ip) }
func TestHandleExitNodeDNSQueryWithNetPkg(t *testing.T) {
if runtime.GOOS == "windows" {
t.Skip("skipping test on Windows; waiting for golang.org/issue/33097")
}
records := []interface{}{
"no-records.test.",
dnsHandler(),
"one-a.test.",
dnsHandler(netaddr.MustParseIP("1.2.3.4")),
"two-a.test.",
dnsHandler(netaddr.MustParseIP("1.2.3.4"), netaddr.MustParseIP("5.6.7.8")),
"one-aaaa.test.",
dnsHandler(netaddr.MustParseIP("1::2")),
"two-aaaa.test.",
dnsHandler(netaddr.MustParseIP("1::2"), netaddr.MustParseIP("3::4")),
"nx-domain.test.",
resolveToNXDOMAIN,
"4.3.2.1.in-addr.arpa.",
dnsHandler(miekdns.PTR{Ptr: "foo.com."}),
"cname.test.",
weirdoGoCNAMEHandler("the-target.foo."),
"txt.test.",
dnsHandler(
miekdns.TXT{Txt: []string{"txt1=one"}},
miekdns.TXT{Txt: []string{"txt2=two"}},
miekdns.TXT{Txt: []string{"txt3=three"}},
),
"srv.test.",
dnsHandler(
miekdns.SRV{
Priority: 1,
Weight: 2,
Port: 3,
Target: "foo.com.",
},
miekdns.SRV{
Priority: 4,
Weight: 5,
Port: 6,
Target: "bar.com.",
},
),
"ns.test.",
dnsHandler(miekdns.NS{Ns: "ns1.foo."}, miekdns.NS{Ns: "ns2.bar."}),
}
v4server := serveDNS(t, "127.0.0.1:0", records...)
defer v4server.Shutdown()
// backendResolver is the resolver between
// handleExitNodeDNSQueryWithNetPkg and its upstream resolver,
// which in this test's case is the miekg/dns test DNS server
// (v4server).
backResolver := &net.Resolver{
PreferGo: true,
Dial: func(ctx context.Context, network, addr string) (net.Conn, error) {
var d net.Dialer
return d.DialContext(ctx, "udp", v4server.PacketConn.LocalAddr().String())
},
}
t.Run("no_such_host", func(t *testing.T) {
res, err := handleExitNodeDNSQueryWithNetPkg(context.Background(), backResolver, &response{
Header: dnsmessage.Header{
ID: 123,
Response: true,
OpCode: 0, // query
},
Question: dnsmessage.Question{
Name: dnsmessage.MustNewName("nx-domain.test."),
Type: dnsmessage.TypeA,
Class: dnsmessage.ClassINET,
},
})
if err != nil {
t.Fatal(err)
}
if len(res) < dnsHeaderLen {
t.Fatal("short reply")
}
rcode := dns.RCode(res[3] & 0x0f)
if rcode != dns.RCodeNameError {
t.Errorf("RCode = %v; want dns.RCodeNameError", rcode)
t.Logf("Response was: %q", res)
}
})
matchPacked := func(want string) func(t testing.TB, got []byte) {
return func(t testing.TB, got []byte) {
if string(got) == want {
return
}
t.Errorf("unexpected reply.\n got: %q\nwant: %q\n", got, want)
t.Errorf("\nin hex:\n got: % 2x\nwant: % 2x\n", got, want)
}
}
tests := []struct {
Type dnsmessage.Type
Name string
Check func(t testing.TB, got []byte)
}{
{
Type: dnsmessage.TypeA,
Name: "one-a.test.",
Check: matchPacked("\x00{\x84\x00\x00\x01\x00\x01\x00\x00\x00\x00\x05one-a\x04test\x00\x00\x01\x00\x01\x05one-a\x04test\x00\x00\x01\x00\x01\x00\x00\x02X\x00\x04\x01\x02\x03\x04"),
},
{
Type: dnsmessage.TypeA,
Name: "two-a.test.",
Check: matchPacked("\x00{\x84\x00\x00\x01\x00\x02\x00\x00\x00\x00\x05two-a\x04test\x00\x00\x01\x00\x01\xc0\f\x00\x01\x00\x01\x00\x00\x02X\x00\x04\x01\x02\x03\x04\xc0\f\x00\x01\x00\x01\x00\x00\x02X\x00\x04\x05\x06\a\b"),
},
{
Type: dnsmessage.TypeAAAA,
Name: "one-aaaa.test.",
Check: matchPacked("\x00{\x84\x00\x00\x01\x00\x01\x00\x00\x00\x00\bone-aaaa\x04test\x00\x00\x1c\x00\x01\bone-aaaa\x04test\x00\x00\x1c\x00\x01\x00\x00\x02X\x00\x10\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02"),
},
{
Type: dnsmessage.TypeAAAA,
Name: "two-aaaa.test.",
Check: matchPacked("\x00{\x84\x00\x00\x01\x00\x02\x00\x00\x00\x00\btwo-aaaa\x04test\x00\x00\x1c\x00\x01\xc0\f\x00\x1c\x00\x01\x00\x00\x02X\x00\x10\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\xc0\f\x00\x1c\x00\x01\x00\x00\x02X\x00\x10\x00\x03\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04"),
},
{
Type: dnsmessage.TypePTR,
Name: "4.3.2.1.in-addr.arpa.",
Check: matchPacked("\x00{\x84\x00\x00\x01\x00\x01\x00\x00\x00\x00\x014\x013\x012\x011\ain-addr\x04arpa\x00\x00\f\x00\x01\x014\x013\x012\x011\ain-addr\x04arpa\x00\x00\f\x00\x01\x00\x00\x02X\x00\t\x03foo\x03com\x00"),
},
{
Type: dnsmessage.TypeCNAME,
Name: "cname.test.",
Check: matchPacked("\x00{\x84\x00\x00\x01\x00\x01\x00\x00\x00\x00\x05cname\x04test\x00\x00\x05\x00\x01\x05cname\x04test\x00\x00\x05\x00\x01\x00\x00\x02X\x00\x10\nthe-target\x03foo\x00"),
},
// No records of various types
{
Type: dnsmessage.TypeA,
Name: "no-records.test.",
Check: matchPacked("\x00{\x84\x03\x00\x01\x00\x00\x00\x00\x00\x00\nno-records\x04test\x00\x00\x01\x00\x01"),
},
{
Type: dnsmessage.TypeAAAA,
Name: "no-records.test.",
Check: matchPacked("\x00{\x84\x03\x00\x01\x00\x00\x00\x00\x00\x00\nno-records\x04test\x00\x00\x1c\x00\x01"),
},
{
Type: dnsmessage.TypeCNAME,
Name: "no-records.test.",
Check: matchPacked("\x00{\x84\x03\x00\x01\x00\x00\x00\x00\x00\x00\nno-records\x04test\x00\x00\x05\x00\x01"),
},
{
Type: dnsmessage.TypeSRV,
Name: "no-records.test.",
Check: matchPacked("\x00{\x84\x03\x00\x01\x00\x00\x00\x00\x00\x00\nno-records\x04test\x00\x00!\x00\x01"),
},
{
Type: dnsmessage.TypeTXT,
Name: "txt.test.",
Check: matchPacked("\x00{\x84\x00\x00\x01\x00\x03\x00\x00\x00\x00\x03txt\x04test\x00\x00\x10\x00\x01\x03txt\x04test\x00\x00\x10\x00\x01\x00\x00\x02X\x00\t\btxt1=one\x03txt\x04test\x00\x00\x10\x00\x01\x00\x00\x02X\x00\t\btxt2=two\x03txt\x04test\x00\x00\x10\x00\x01\x00\x00\x02X\x00\v\ntxt3=three"),
},
{
Type: dnsmessage.TypeSRV,
Name: "srv.test.",
Check: matchPacked("\x00{\x84\x00\x00\x01\x00\x02\x00\x00\x00\x00\x03srv\x04test\x00\x00!\x00\x01\x03srv\x04test\x00\x00!\x00\x01\x00\x00\x02X\x00\x0f\x00\x01\x00\x02\x00\x03\x03foo\x03com\x00\x03srv\x04test\x00\x00!\x00\x01\x00\x00\x02X\x00\x0f\x00\x04\x00\x05\x00\x06\x03bar\x03com\x00"),
},
{
Type: dnsmessage.TypeNS,
Name: "ns.test.",
Check: matchPacked("\x00{\x84\x00\x00\x01\x00\x02\x00\x00\x00\x00\x02ns\x04test\x00\x00\x02\x00\x01\x02ns\x04test\x00\x00\x02\x00\x01\x00\x00\x02X\x00\t\x03ns1\x03foo\x00\x02ns\x04test\x00\x00\x02\x00\x01\x00\x00\x02X\x00\t\x03ns2\x03bar\x00"),
},
}
for _, tt := range tests {
t.Run(fmt.Sprintf("%v_%v", tt.Type, strings.Trim(tt.Name, ".")), func(t *testing.T) {
got, err := handleExitNodeDNSQueryWithNetPkg(context.Background(), backResolver, &response{
Header: dnsmessage.Header{
ID: 123,
Response: true,
OpCode: 0, // query
},
Question: dnsmessage.Question{
Name: dnsmessage.MustNewName(tt.Name),
Type: tt.Type,
Class: dnsmessage.ClassINET,
},
})
if err != nil {
t.Fatal(err)
}
if len(got) < dnsHeaderLen {
t.Errorf("short record")
}
if tt.Check != nil {
tt.Check(t, got)
if t.Failed() {
t.Errorf("Got: %q\nIn hex: % 02x", got, got)
}
}
})
}
wrapRes := newWrapResolver(backResolver)
ctx := context.Background()
t.Run("wrap_ip_a", func(t *testing.T) {
ips, err := wrapRes.LookupIP(ctx, "ip", "two-a.test.")
if err != nil {
t.Fatal(err)
}
if got, want := ips, []net.IP{
net.ParseIP("1.2.3.4").To4(),
net.ParseIP("5.6.7.8").To4(),
}; !reflect.DeepEqual(got, want) {
t.Errorf("LookupIP = %v; want %v", got, want)
}
})
t.Run("wrap_ip_aaaa", func(t *testing.T) {
ips, err := wrapRes.LookupIP(ctx, "ip", "two-aaaa.test.")
if err != nil {
t.Fatal(err)
}
if got, want := ips, []net.IP{
net.ParseIP("1::2"),
net.ParseIP("3::4"),
}; !reflect.DeepEqual(got, want) {
t.Errorf("LookupIP(v6) = %v; want %v", got, want)
}
})
t.Run("wrap_ip_nx", func(t *testing.T) {
ips, err := wrapRes.LookupIP(ctx, "ip", "nx-domain.test.")
if !isGoNoSuchHostError(err) {
t.Errorf("no NX domain = (%v, %v); want no host error", ips, err)
}
})
t.Run("wrap_srv", func(t *testing.T) {
_, srvs, err := wrapRes.LookupSRV(ctx, "", "", "srv.test.")
if err != nil {
t.Fatal(err)
}
if got, want := srvs, []*net.SRV{
{
Target: "foo.com.",
Priority: 1,
Weight: 2,
Port: 3,
},
{
Target: "bar.com.",
Priority: 4,
Weight: 5,
Port: 6,
},
}; !reflect.DeepEqual(got, want) {
jgot, _ := json.Marshal(got)
jwant, _ := json.Marshal(want)
t.Errorf("SRV = %s; want %s", jgot, jwant)
}
})
t.Run("wrap_txt", func(t *testing.T) {
txts, err := wrapRes.LookupTXT(ctx, "txt.test.")
if err != nil {
t.Fatal(err)
}
if got, want := txts, []string{"txt1=one", "txt2=two", "txt3=three"}; !reflect.DeepEqual(got, want) {
t.Errorf("TXT = %q; want %q", got, want)
}
})
t.Run("wrap_ns", func(t *testing.T) {
nss, err := wrapRes.LookupNS(ctx, "ns.test.")
if err != nil {
t.Fatal(err)
}
if got, want := nss, []*net.NS{
{Host: "ns1.foo."},
{Host: "ns2.bar."},
}; !reflect.DeepEqual(got, want) {
jgot, _ := json.Marshal(got)
jwant, _ := json.Marshal(want)
t.Errorf("NS = %s; want %s", jgot, jwant)
}
})
}
// newWrapResolver returns a resolver that uses r (via handleExitNodeDNSQueryWithNetPkg)
// to make DNS requests.
func newWrapResolver(r *net.Resolver) *net.Resolver {
if runtime.GOOS == "windows" {
panic("doesn't work on Windows") // golang.org/issue/33097
}
return &net.Resolver{
PreferGo: true,
Dial: func(ctx context.Context, network, addr string) (net.Conn, error) {
return &wrapResolverConn{ctx: ctx, r: r}, nil
},
}
}
type wrapResolverConn struct {
ctx context.Context
r *net.Resolver
buf bytes.Buffer
}
var _ net.PacketConn = (*wrapResolverConn)(nil)
func (*wrapResolverConn) Close() error { return nil }
func (*wrapResolverConn) LocalAddr() net.Addr { return fakeAddr{} }
func (*wrapResolverConn) RemoteAddr() net.Addr { return fakeAddr{} }
func (*wrapResolverConn) SetDeadline(t time.Time) error { return nil }
func (*wrapResolverConn) SetReadDeadline(t time.Time) error { return nil }
func (*wrapResolverConn) SetWriteDeadline(t time.Time) error { return nil }
func (a *wrapResolverConn) Read(p []byte) (n int, err error) {
n, _, err = a.ReadFrom(p)
return
}
func (a *wrapResolverConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
n, err = a.buf.Read(p)
return n, fakeAddr{}, err
}
func (a *wrapResolverConn) Write(packet []byte) (n int, err error) {
return a.WriteTo(packet, fakeAddr{})
}
func (a *wrapResolverConn) WriteTo(q []byte, _ net.Addr) (n int, err error) {
resp := parseExitNodeQuery(q)
if resp == nil {
return 0, errors.New("bad query")
}
res, err := handleExitNodeDNSQueryWithNetPkg(context.Background(), a.r, resp)
if err != nil {
return 0, err
}
a.buf.Write(res)
return len(q), nil
}
type fakeAddr struct{}
func (fakeAddr) Network() string { return "unused" }
func (fakeAddr) String() string { return "unused-todoAddr" }
func TestUnARPA(t *testing.T) {
tests := []struct {
in, want string
}{
{"", ""},
{"bad", ""},
{"4.4.8.8.in-addr.arpa.", "8.8.4.4"},
{".in-addr.arpa.", ""},
{"e.0.0.2.0.0.0.0.0.0.0.0.0.0.0.0.b.0.8.0.a.0.0.4.0.b.8.f.7.0.6.2.ip6.arpa.", "2607:f8b0:400a:80b::200e"},
{".ip6.arpa.", ""},
}
for _, tt := range tests {
got, ok := unARPA(tt.in)
if ok != (got != "") {
t.Errorf("inconsistent results for %q: (%q, %v)", tt.in, got, ok)
}
if got != tt.want {
t.Errorf("unARPA(%q) = %q; want %q", tt.in, got, tt.want)
}
}
}

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