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https://github.com/tailscale/tailscale.git
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net/dns/recursive: add initial implementation of recursive DNS resolver
We've talked in the past about reworking how bootstrap DNS works to instead do recursive DNS resolution from the root; this would better support on-prem customers and Headscale users where the DERP servers don't currently resolve their DNS server. This package is an initial implementation of recursive resolution for A and AAAA records. Updates #5853 Change-Id: Ibe974d78709b4b03674b47c4ef61f9a00addf8b4 Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
This commit is contained in:
Andrew Dunham
741
net/dns/recursive/recursive_test.go
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741
net/dns/recursive/recursive_test.go
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@@ -0,0 +1,741 @@
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package recursive
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import (
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"context"
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"errors"
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"flag"
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"fmt"
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"net"
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"net/netip"
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"reflect"
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"strings"
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"testing"
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"time"
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"github.com/miekg/dns"
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"golang.org/x/exp/slices"
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"tailscale.com/envknob"
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"tailscale.com/tstest"
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)
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const testDomain = "tailscale.com"
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// Recursively resolving the AWS console requires being able to handle CNAMEs,
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// glue records, falling back from UDP to TCP for oversize queries, and more;
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// it's a great integration test for DNS resolution and they can handle the
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// traffic :)
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const complicatedTestDomain = "console.aws.amazon.com"
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var flagNetworkAccess = flag.Bool("enable-network-access", false, "run tests that need external network access")
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func init() {
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envknob.Setenv("TS_DEBUG_RECURSIVE_DNS", "true")
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}
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func newResolver(tb testing.TB) *Resolver {
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clock := &tstest.Clock{
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Step: 50 * time.Millisecond,
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}
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return &Resolver{
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Logf: tb.Logf,
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timeNow: clock.Now,
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}
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}
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func TestResolve(t *testing.T) {
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if !*flagNetworkAccess {
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t.SkipNow()
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}
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ctx := context.Background()
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r := newResolver(t)
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addrs, minTTL, err := r.Resolve(ctx, testDomain)
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if err != nil {
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t.Fatal(err)
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}
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t.Logf("addrs: %+v", addrs)
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t.Logf("minTTL: %v", minTTL)
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if len(addrs) < 1 {
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t.Fatalf("expected at least one address")
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}
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if minTTL <= 10*time.Second || minTTL >= 24*time.Hour {
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t.Errorf("invalid minimum TTL: %v", minTTL)
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}
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var has4, has6 bool
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for _, addr := range addrs {
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has4 = has4 || addr.Is4()
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has6 = has6 || addr.Is6()
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}
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if !has4 {
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t.Errorf("expected at least one IPv4 address")
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}
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if !has6 {
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t.Errorf("expected at least one IPv6 address")
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}
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}
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func TestResolveComplicated(t *testing.T) {
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if !*flagNetworkAccess {
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t.SkipNow()
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}
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ctx := context.Background()
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r := newResolver(t)
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addrs, minTTL, err := r.Resolve(ctx, complicatedTestDomain)
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if err != nil {
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t.Fatal(err)
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}
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t.Logf("addrs: %+v", addrs)
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t.Logf("minTTL: %v", minTTL)
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if len(addrs) < 1 {
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t.Fatalf("expected at least one address")
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}
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if minTTL <= 10*time.Second || minTTL >= 24*time.Hour {
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t.Errorf("invalid minimum TTL: %v", minTTL)
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}
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}
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func TestResolveNoIPv6(t *testing.T) {
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if !*flagNetworkAccess {
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t.SkipNow()
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}
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r := newResolver(t)
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r.NoIPv6 = true
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addrs, _, err := r.Resolve(context.Background(), testDomain)
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if err != nil {
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t.Fatal(err)
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}
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t.Logf("addrs: %+v", addrs)
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if len(addrs) < 1 {
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t.Fatalf("expected at least one address")
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}
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for _, addr := range addrs {
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if addr.Is6() {
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t.Errorf("got unexpected IPv6 address: %v", addr)
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}
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}
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}
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func TestResolveFallbackToTCP(t *testing.T) {
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var udpCalls, tcpCalls int
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hook := func(nameserver netip.Addr, network string, req *dns.Msg) (*dns.Msg, error) {
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if strings.HasPrefix(network, "udp") {
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t.Logf("got %q query; returning truncated result", network)
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udpCalls++
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resp := &dns.Msg{}
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resp.SetReply(req)
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resp.Truncated = true
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return resp, nil
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}
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t.Logf("got %q query; returning real result", network)
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tcpCalls++
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resp := &dns.Msg{}
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resp.SetReply(req)
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resp.Answer = append(resp.Answer, &dns.A{
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Hdr: dns.RR_Header{
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Name: req.Question[0].Name,
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Rrtype: req.Question[0].Qtype,
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Class: dns.ClassINET,
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Ttl: 300,
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},
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A: net.IPv4(1, 2, 3, 4),
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})
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return resp, nil
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}
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r := newResolver(t)
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r.testExchangeHook = hook
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ctx := context.Background()
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resp, err := r.queryNameserverProto(ctx, 0, "tailscale.com", netip.MustParseAddr("9.9.9.9"), "udp", dns.Type(dns.TypeA))
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if err != nil {
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t.Fatal(err)
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}
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if len(resp.Answer) < 1 {
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t.Fatalf("no answers in response: %v", resp)
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}
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rrA, ok := resp.Answer[0].(*dns.A)
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if !ok {
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t.Fatalf("invalid RR type: %T", resp.Answer[0])
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}
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if !rrA.A.Equal(net.IPv4(1, 2, 3, 4)) {
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t.Errorf("wanted A response 1.2.3.4, got: %v", rrA.A)
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}
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if tcpCalls != 1 {
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t.Errorf("got %d, want 1 TCP calls", tcpCalls)
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}
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if udpCalls != 1 {
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t.Errorf("got %d, want 1 UDP calls", udpCalls)
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}
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// Verify that we're cached and re-run to fetch from the cache.
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if len(r.queryCache) < 1 {
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t.Errorf("wanted entries in the query cache")
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}
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resp2, err := r.queryNameserverProto(ctx, 0, "tailscale.com", netip.MustParseAddr("9.9.9.9"), "udp", dns.Type(dns.TypeA))
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if err != nil {
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t.Fatal(err)
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}
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if !reflect.DeepEqual(resp, resp2) {
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t.Errorf("expected equal responses; old=%+v new=%+v", resp, resp2)
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}
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// We didn't make any more network requests since we loaded from the cache.
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if tcpCalls != 1 {
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t.Errorf("got %d, want 1 TCP calls", tcpCalls)
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}
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if udpCalls != 1 {
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t.Errorf("got %d, want 1 UDP calls", udpCalls)
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}
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}
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func dnsIPRR(name string, addr netip.Addr) dns.RR {
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if addr.Is4() {
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return &dns.A{
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Hdr: dns.RR_Header{
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Name: name,
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Rrtype: dns.TypeA,
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Class: dns.ClassINET,
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Ttl: 300,
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},
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A: net.IP(addr.AsSlice()),
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}
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}
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return &dns.AAAA{
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Hdr: dns.RR_Header{
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Name: name,
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Rrtype: dns.TypeAAAA,
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Class: dns.ClassINET,
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Ttl: 300,
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},
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AAAA: net.IP(addr.AsSlice()),
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}
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}
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func cnameRR(name, target string) dns.RR {
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return &dns.CNAME{
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Hdr: dns.RR_Header{
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Name: name,
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Rrtype: dns.TypeCNAME,
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Class: dns.ClassINET,
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Ttl: 300,
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},
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Target: target,
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}
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}
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func nsRR(name, target string) dns.RR {
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return &dns.NS{
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Hdr: dns.RR_Header{
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Name: name,
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Rrtype: dns.TypeNS,
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Class: dns.ClassINET,
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Ttl: 300,
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},
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Ns: target,
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}
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}
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type mockReply struct {
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name string
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qtype dns.Type
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resp *dns.Msg
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}
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type replyMock struct {
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tb testing.TB
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replies map[netip.Addr][]mockReply
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}
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func (r *replyMock) exchangeHook(nameserver netip.Addr, network string, req *dns.Msg) (*dns.Msg, error) {
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if len(req.Question) != 1 {
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r.tb.Fatalf("unsupported multiple or empty question: %v", req.Question)
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}
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question := req.Question[0]
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replies := r.replies[nameserver]
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if len(replies) == 0 {
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r.tb.Fatalf("no configured replies for nameserver: %v", nameserver)
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}
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for _, reply := range replies {
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if reply.name == question.Name && reply.qtype == dns.Type(question.Qtype) {
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return reply.resp.Copy(), nil
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}
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}
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r.tb.Fatalf("no replies found for query %q of type %v to %v", question.Name, question.Qtype, nameserver)
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panic("unreachable")
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}
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// responses for mocking, shared between the following tests
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var (
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rootServerAddr = netip.MustParseAddr("198.41.0.4") // a.root-servers.net.
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comNSAddr = netip.MustParseAddr("192.5.6.30") // a.gtld-servers.net.
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// DNS response from the root nameservers for a .com nameserver
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comRecord = &dns.Msg{
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Ns: []dns.RR{nsRR("com.", "a.gtld-servers.net.")},
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Extra: []dns.RR{dnsIPRR("a.gtld-servers.net.", comNSAddr)},
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}
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// Random Amazon nameservers that we use in glue records
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amazonNS = netip.MustParseAddr("205.251.192.197")
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amazonNSv6 = netip.MustParseAddr("2600:9000:5306:1600::1")
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// Nameservers for the tailscale.com domain
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tailscaleNameservers = &dns.Msg{
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Ns: []dns.RR{
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nsRR("tailscale.com.", "ns-197.awsdns-24.com."),
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nsRR("tailscale.com.", "ns-557.awsdns-05.net."),
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nsRR("tailscale.com.", "ns-1558.awsdns-02.co.uk."),
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nsRR("tailscale.com.", "ns-1359.awsdns-41.org."),
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},
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Extra: []dns.RR{
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dnsIPRR("ns-197.awsdns-24.com.", amazonNS),
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},
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}
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)
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func TestBasicRecursion(t *testing.T) {
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mock := &replyMock{
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tb: t,
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replies: map[netip.Addr][]mockReply{
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// Query to the root server returns the .com server + a glue record
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rootServerAddr: {
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: comRecord},
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: comRecord},
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},
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// Query to the ".com" server return the nameservers for tailscale.com
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comNSAddr: {
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: tailscaleNameservers},
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: tailscaleNameservers},
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},
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// Query to the actual nameserver works.
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amazonNS: {
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: &dns.Msg{
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MsgHdr: dns.MsgHdr{Authoritative: true},
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Answer: []dns.RR{
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dnsIPRR("tailscale.com.", netip.MustParseAddr("13.248.141.131")),
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dnsIPRR("tailscale.com.", netip.MustParseAddr("76.223.15.28")),
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},
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}},
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: &dns.Msg{
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MsgHdr: dns.MsgHdr{Authoritative: true},
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Answer: []dns.RR{
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dnsIPRR("tailscale.com.", netip.MustParseAddr("2600:9000:a602:b1e6:86d:8165:5e8c:295b")),
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dnsIPRR("tailscale.com.", netip.MustParseAddr("2600:9000:a51d:27c1:1530:b9ef:2a6:b9e5")),
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},
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}},
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},
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},
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}
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r := newResolver(t)
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r.testExchangeHook = mock.exchangeHook
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r.rootServers = []netip.Addr{rootServerAddr}
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// Query for tailscale.com, verify we get the right responses
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ctx := context.Background()
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addrs, minTTL, err := r.Resolve(ctx, "tailscale.com")
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if err != nil {
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t.Fatal(err)
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}
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wantAddrs := []netip.Addr{
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netip.MustParseAddr("13.248.141.131"),
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netip.MustParseAddr("76.223.15.28"),
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netip.MustParseAddr("2600:9000:a602:b1e6:86d:8165:5e8c:295b"),
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netip.MustParseAddr("2600:9000:a51d:27c1:1530:b9ef:2a6:b9e5"),
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}
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slices.SortFunc(addrs, func(x, y netip.Addr) bool { return x.String() < y.String() })
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slices.SortFunc(wantAddrs, func(x, y netip.Addr) bool { return x.String() < y.String() })
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if !reflect.DeepEqual(addrs, wantAddrs) {
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t.Errorf("got addrs=%+v; want %+v", addrs, wantAddrs)
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}
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const wantMinTTL = 5 * time.Minute
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if minTTL != wantMinTTL {
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t.Errorf("got minTTL=%+v; want %+v", minTTL, wantMinTTL)
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}
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}
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func TestNoAnswers(t *testing.T) {
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mock := &replyMock{
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tb: t,
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replies: map[netip.Addr][]mockReply{
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// Query to the root server returns the .com server + a glue record
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rootServerAddr: {
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: comRecord},
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: comRecord},
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},
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// Query to the ".com" server return the nameservers for tailscale.com
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comNSAddr: {
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: tailscaleNameservers},
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: tailscaleNameservers},
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},
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// Query to the actual nameserver returns no responses, authoritatively.
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amazonNS: {
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: &dns.Msg{
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MsgHdr: dns.MsgHdr{Authoritative: true},
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Answer: []dns.RR{},
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}},
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{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: &dns.Msg{
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MsgHdr: dns.MsgHdr{Authoritative: true},
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Answer: []dns.RR{},
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}},
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},
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},
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}
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r := &Resolver{
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Logf: t.Logf,
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testExchangeHook: mock.exchangeHook,
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rootServers: []netip.Addr{rootServerAddr},
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}
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// Query for tailscale.com, verify we get the right responses
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_, _, err := r.Resolve(context.Background(), "tailscale.com")
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if err == nil {
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t.Fatalf("got no error, want error")
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}
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if !errors.Is(err, ErrAuthoritativeNoResponses) {
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t.Fatalf("got err=%v, want %v", err, ErrAuthoritativeNoResponses)
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}
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}
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func TestRecursionCNAME(t *testing.T) {
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mock := &replyMock{
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tb: t,
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replies: map[netip.Addr][]mockReply{
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// Query to the root server returns the .com server + a glue record
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rootServerAddr: {
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{name: "subdomain.otherdomain.com.", qtype: dns.Type(dns.TypeA), resp: comRecord},
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{name: "subdomain.otherdomain.com.", qtype: dns.Type(dns.TypeAAAA), resp: comRecord},
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{name: "subdomain.tailscale.com.", qtype: dns.Type(dns.TypeA), resp: comRecord},
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{name: "subdomain.tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: comRecord},
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},
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// Query to the ".com" server return the nameservers for tailscale.com
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comNSAddr: {
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{name: "subdomain.otherdomain.com.", qtype: dns.Type(dns.TypeA), resp: tailscaleNameservers},
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{name: "subdomain.otherdomain.com.", qtype: dns.Type(dns.TypeAAAA), resp: tailscaleNameservers},
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{name: "subdomain.tailscale.com.", qtype: dns.Type(dns.TypeA), resp: tailscaleNameservers},
|
||||
{name: "subdomain.tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: tailscaleNameservers},
|
||||
},
|
||||
|
||||
// Query to the actual nameserver works.
|
||||
amazonNS: {
|
||||
{name: "subdomain.otherdomain.com.", qtype: dns.Type(dns.TypeA), resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
Answer: []dns.RR{cnameRR("subdomain.otherdomain.com.", "subdomain.tailscale.com.")},
|
||||
}},
|
||||
{name: "subdomain.otherdomain.com.", qtype: dns.Type(dns.TypeAAAA), resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
Answer: []dns.RR{cnameRR("subdomain.otherdomain.com.", "subdomain.tailscale.com.")},
|
||||
}},
|
||||
|
||||
{name: "subdomain.tailscale.com.", qtype: dns.Type(dns.TypeA), resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
Answer: []dns.RR{dnsIPRR("tailscale.com.", netip.MustParseAddr("13.248.141.131"))},
|
||||
}},
|
||||
{name: "subdomain.tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
Answer: []dns.RR{dnsIPRR("tailscale.com.", netip.MustParseAddr("2600:9000:a602:b1e6:86d:8165:5e8c:295b"))},
|
||||
}},
|
||||
},
|
||||
},
|
||||
}
|
||||
|
||||
r := &Resolver{
|
||||
Logf: t.Logf,
|
||||
testExchangeHook: mock.exchangeHook,
|
||||
rootServers: []netip.Addr{rootServerAddr},
|
||||
}
|
||||
|
||||
// Query for tailscale.com, verify we get the right responses
|
||||
addrs, minTTL, err := r.Resolve(context.Background(), "subdomain.otherdomain.com")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
wantAddrs := []netip.Addr{
|
||||
netip.MustParseAddr("13.248.141.131"),
|
||||
netip.MustParseAddr("2600:9000:a602:b1e6:86d:8165:5e8c:295b"),
|
||||
}
|
||||
slices.SortFunc(addrs, func(x, y netip.Addr) bool { return x.String() < y.String() })
|
||||
slices.SortFunc(wantAddrs, func(x, y netip.Addr) bool { return x.String() < y.String() })
|
||||
|
||||
if !reflect.DeepEqual(addrs, wantAddrs) {
|
||||
t.Errorf("got addrs=%+v; want %+v", addrs, wantAddrs)
|
||||
}
|
||||
|
||||
const wantMinTTL = 5 * time.Minute
|
||||
if minTTL != wantMinTTL {
|
||||
t.Errorf("got minTTL=%+v; want %+v", minTTL, wantMinTTL)
|
||||
}
|
||||
}
|
||||
|
||||
func TestRecursionNoGlue(t *testing.T) {
|
||||
coukNS := netip.MustParseAddr("213.248.216.1")
|
||||
coukRecord := &dns.Msg{
|
||||
Ns: []dns.RR{nsRR("com.", "dns1.nic.uk.")},
|
||||
Extra: []dns.RR{dnsIPRR("dns1.nic.uk.", coukNS)},
|
||||
}
|
||||
|
||||
intermediateNS := netip.MustParseAddr("205.251.193.66") // g-ns-322.awsdns-02.co.uk.
|
||||
intermediateRecord := &dns.Msg{
|
||||
Ns: []dns.RR{nsRR("awsdns-02.co.uk.", "g-ns-322.awsdns-02.co.uk.")},
|
||||
Extra: []dns.RR{dnsIPRR("g-ns-322.awsdns-02.co.uk.", intermediateNS)},
|
||||
}
|
||||
|
||||
const amazonNameserver = "ns-1558.awsdns-02.co.uk."
|
||||
tailscaleNameservers := &dns.Msg{
|
||||
Ns: []dns.RR{
|
||||
nsRR("tailscale.com.", amazonNameserver),
|
||||
},
|
||||
}
|
||||
|
||||
tailscaleResponses := []mockReply{
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
Answer: []dns.RR{dnsIPRR("tailscale.com.", netip.MustParseAddr("13.248.141.131"))},
|
||||
}},
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
Answer: []dns.RR{dnsIPRR("tailscale.com.", netip.MustParseAddr("2600:9000:a602:b1e6:86d:8165:5e8c:295b"))},
|
||||
}},
|
||||
}
|
||||
|
||||
mock := &replyMock{
|
||||
tb: t,
|
||||
replies: map[netip.Addr][]mockReply{
|
||||
rootServerAddr: {
|
||||
// Query to the root server returns the .com server + a glue record
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: comRecord},
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: comRecord},
|
||||
|
||||
// Querying the .co.uk nameserver returns the .co.uk nameserver + a glue record.
|
||||
{name: amazonNameserver, qtype: dns.Type(dns.TypeA), resp: coukRecord},
|
||||
{name: amazonNameserver, qtype: dns.Type(dns.TypeAAAA), resp: coukRecord},
|
||||
},
|
||||
|
||||
// Queries to the ".com" server return the nameservers
|
||||
// for tailscale.com, which don't contain a glue
|
||||
// record.
|
||||
comNSAddr: {
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: tailscaleNameservers},
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: tailscaleNameservers},
|
||||
},
|
||||
|
||||
// Queries to the ".co.uk" nameserver returns the
|
||||
// address of the intermediate Amazon nameserver.
|
||||
coukNS: {
|
||||
{name: amazonNameserver, qtype: dns.Type(dns.TypeA), resp: intermediateRecord},
|
||||
{name: amazonNameserver, qtype: dns.Type(dns.TypeAAAA), resp: intermediateRecord},
|
||||
},
|
||||
|
||||
// Queries to the intermediate nameserver returns an
|
||||
// answer for the final Amazon nameserver.
|
||||
intermediateNS: {
|
||||
{name: amazonNameserver, qtype: dns.Type(dns.TypeA), resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
Answer: []dns.RR{dnsIPRR(amazonNameserver, amazonNS)},
|
||||
}},
|
||||
{name: amazonNameserver, qtype: dns.Type(dns.TypeAAAA), resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
Answer: []dns.RR{dnsIPRR(amazonNameserver, amazonNSv6)},
|
||||
}},
|
||||
},
|
||||
|
||||
// Queries to the actual nameserver work and return
|
||||
// responses to the query.
|
||||
amazonNS: tailscaleResponses,
|
||||
amazonNSv6: tailscaleResponses,
|
||||
},
|
||||
}
|
||||
|
||||
r := newResolver(t)
|
||||
r.testExchangeHook = mock.exchangeHook
|
||||
r.rootServers = []netip.Addr{rootServerAddr}
|
||||
|
||||
// Query for tailscale.com, verify we get the right responses
|
||||
addrs, minTTL, err := r.Resolve(context.Background(), "tailscale.com")
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
wantAddrs := []netip.Addr{
|
||||
netip.MustParseAddr("13.248.141.131"),
|
||||
netip.MustParseAddr("2600:9000:a602:b1e6:86d:8165:5e8c:295b"),
|
||||
}
|
||||
slices.SortFunc(addrs, func(x, y netip.Addr) bool { return x.String() < y.String() })
|
||||
slices.SortFunc(wantAddrs, func(x, y netip.Addr) bool { return x.String() < y.String() })
|
||||
|
||||
if !reflect.DeepEqual(addrs, wantAddrs) {
|
||||
t.Errorf("got addrs=%+v; want %+v", addrs, wantAddrs)
|
||||
}
|
||||
|
||||
const wantMinTTL = 5 * time.Minute
|
||||
if minTTL != wantMinTTL {
|
||||
t.Errorf("got minTTL=%+v; want %+v", minTTL, wantMinTTL)
|
||||
}
|
||||
}
|
||||
|
||||
func TestRecursionLimit(t *testing.T) {
|
||||
mock := &replyMock{
|
||||
tb: t,
|
||||
replies: map[netip.Addr][]mockReply{},
|
||||
}
|
||||
|
||||
// Fill out a CNAME chain equal to our recursion limit; we won't get
|
||||
// this far since each CNAME is more than 1 level "deep", but this
|
||||
// ensures that we have more than the limit.
|
||||
for i := 0; i < maxDepth+1; i++ {
|
||||
curr := fmt.Sprintf("%d-tailscale.com.", i)
|
||||
|
||||
tailscaleNameservers := &dns.Msg{
|
||||
Ns: []dns.RR{nsRR(curr, "ns-197.awsdns-24.com.")},
|
||||
Extra: []dns.RR{dnsIPRR("ns-197.awsdns-24.com.", amazonNS)},
|
||||
}
|
||||
|
||||
// Query to the root server returns the .com server + a glue record
|
||||
mock.replies[rootServerAddr] = append(mock.replies[rootServerAddr],
|
||||
mockReply{name: curr, qtype: dns.Type(dns.TypeA), resp: comRecord},
|
||||
mockReply{name: curr, qtype: dns.Type(dns.TypeAAAA), resp: comRecord},
|
||||
)
|
||||
|
||||
// Query to the ".com" server return the nameservers for NN-tailscale.com
|
||||
mock.replies[comNSAddr] = append(mock.replies[comNSAddr],
|
||||
mockReply{name: curr, qtype: dns.Type(dns.TypeA), resp: tailscaleNameservers},
|
||||
mockReply{name: curr, qtype: dns.Type(dns.TypeAAAA), resp: tailscaleNameservers},
|
||||
)
|
||||
|
||||
// Queries to the nameserver return a CNAME for the n+1th server.
|
||||
next := fmt.Sprintf("%d-tailscale.com.", i+1)
|
||||
mock.replies[amazonNS] = append(mock.replies[amazonNS],
|
||||
mockReply{
|
||||
name: curr,
|
||||
qtype: dns.Type(dns.TypeA),
|
||||
resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
Answer: []dns.RR{cnameRR(curr, next)},
|
||||
},
|
||||
},
|
||||
mockReply{
|
||||
name: curr,
|
||||
qtype: dns.Type(dns.TypeAAAA),
|
||||
resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
Answer: []dns.RR{cnameRR(curr, next)},
|
||||
},
|
||||
},
|
||||
)
|
||||
}
|
||||
|
||||
r := newResolver(t)
|
||||
r.testExchangeHook = mock.exchangeHook
|
||||
r.rootServers = []netip.Addr{rootServerAddr}
|
||||
|
||||
// Query for the first node in the chain, 0-tailscale.com, and verify
|
||||
// we get a max-depth error.
|
||||
ctx := context.Background()
|
||||
_, _, err := r.Resolve(ctx, "0-tailscale.com")
|
||||
if err == nil {
|
||||
t.Fatal("expected error, got nil")
|
||||
} else if !errors.Is(err, ErrMaxDepth) {
|
||||
t.Fatalf("got err=%v, want ErrMaxDepth", err)
|
||||
}
|
||||
}
|
||||
|
||||
func TestInvalidResponses(t *testing.T) {
|
||||
mock := &replyMock{
|
||||
tb: t,
|
||||
replies: map[netip.Addr][]mockReply{
|
||||
// Query to the root server returns the .com server + a glue record
|
||||
rootServerAddr: {
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: comRecord},
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: comRecord},
|
||||
},
|
||||
|
||||
// Query to the ".com" server return the nameservers for tailscale.com
|
||||
comNSAddr: {
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: tailscaleNameservers},
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: tailscaleNameservers},
|
||||
},
|
||||
|
||||
// Query to the actual nameserver returns an invalid IP address
|
||||
amazonNS: {
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeA), resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
Answer: []dns.RR{&dns.A{
|
||||
Hdr: dns.RR_Header{
|
||||
Name: "tailscale.com.",
|
||||
Rrtype: dns.TypeA,
|
||||
Class: dns.ClassINET,
|
||||
Ttl: 300,
|
||||
},
|
||||
// Note: this is an IPv6 addr in an IPv4 response
|
||||
A: net.IP(netip.MustParseAddr("2600:9000:a51d:27c1:1530:b9ef:2a6:b9e5").AsSlice()),
|
||||
}},
|
||||
}},
|
||||
{name: "tailscale.com.", qtype: dns.Type(dns.TypeAAAA), resp: &dns.Msg{
|
||||
MsgHdr: dns.MsgHdr{Authoritative: true},
|
||||
// This an IPv4 response to an IPv6 query
|
||||
Answer: []dns.RR{&dns.A{
|
||||
Hdr: dns.RR_Header{
|
||||
Name: "tailscale.com.",
|
||||
Rrtype: dns.TypeA,
|
||||
Class: dns.ClassINET,
|
||||
Ttl: 300,
|
||||
},
|
||||
A: net.IP(netip.MustParseAddr("13.248.141.131").AsSlice()),
|
||||
}},
|
||||
}},
|
||||
},
|
||||
},
|
||||
}
|
||||
|
||||
r := &Resolver{
|
||||
Logf: t.Logf,
|
||||
testExchangeHook: mock.exchangeHook,
|
||||
rootServers: []netip.Addr{rootServerAddr},
|
||||
}
|
||||
|
||||
// Query for tailscale.com, verify we get no responses since the
|
||||
// addresses are invalid.
|
||||
_, _, err := r.Resolve(context.Background(), "tailscale.com")
|
||||
if err == nil {
|
||||
t.Fatalf("got no error, want error")
|
||||
}
|
||||
if !errors.Is(err, ErrAuthoritativeNoResponses) {
|
||||
t.Fatalf("got err=%v, want %v", err, ErrAuthoritativeNoResponses)
|
||||
}
|
||||
}
|
||||
|
||||
// TODO(andrew): test for more edge cases that aren't currently covered:
|
||||
// * Nameservers that cross between IPv4 and IPv6
|
||||
// * Authoritative no replies after following CNAME
|
||||
// * Authoritative no replies after following non-glue NS record
|
||||
// * Error querying non-glue NS record followed by success
|
||||
Reference in New Issue
Block a user