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6f2bae019f
Return empty response and NOERROR for AAAA record queries for DNS names for which we have an A record. This is to allow for callers that might be first sending an AAAA query and then, if that does not return a response, follow with an A record query. Previously we were returning NOTIMPL that caused some callers to potentially not follow with an A record query or misbehave in different ways. Also return NXDOMAIN for AAAA record queries for names that we DO NOT have an A record for to ensure that the callers do not follow up with an A record query. Returning an empty response and NOERROR is the behaviour that RFC 4074 recommends: https://datatracker.ietf.org/doc/html/rfc4074 Updates tailscale/tailscale#12321 Signed-off-by: Irbe Krumina <irbe@tailscale.com>
230 lines
6.9 KiB
Go
230 lines
6.9 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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//go:build !plan9
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package main
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import (
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"net"
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"testing"
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"github.com/google/go-cmp/cmp"
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"github.com/miekg/dns"
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"tailscale.com/util/dnsname"
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)
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func TestNameserver(t *testing.T) {
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tests := []struct {
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name string
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ip4 map[dnsname.FQDN][]net.IP
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query *dns.Msg
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wantResp *dns.Msg
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}{
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{
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name: "A record query, record exists",
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ip4: map[dnsname.FQDN][]net.IP{dnsname.FQDN("foo.bar.com."): {{1, 2, 3, 4}}},
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query: &dns.Msg{
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Question: []dns.Question{{Name: "foo.bar.com", Qtype: dns.TypeA}},
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MsgHdr: dns.MsgHdr{Id: 1, RecursionDesired: true},
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},
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wantResp: &dns.Msg{
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Answer: []dns.RR{&dns.A{Hdr: dns.RR_Header{
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Name: "foo.bar.com", Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 0},
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A: net.IP{1, 2, 3, 4}}},
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Question: []dns.Question{{Name: "foo.bar.com", Qtype: dns.TypeA}},
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MsgHdr: dns.MsgHdr{
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Id: 1,
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Rcode: dns.RcodeSuccess,
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RecursionAvailable: false,
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RecursionDesired: true,
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Response: true,
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Opcode: dns.OpcodeQuery,
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Authoritative: true,
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}},
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},
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{
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name: "A record query, record does not exist",
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ip4: map[dnsname.FQDN][]net.IP{dnsname.FQDN("foo.bar.com."): {{1, 2, 3, 4}}},
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query: &dns.Msg{
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Question: []dns.Question{{Name: "baz.bar.com", Qtype: dns.TypeA}},
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MsgHdr: dns.MsgHdr{Id: 1},
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},
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wantResp: &dns.Msg{
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Question: []dns.Question{{Name: "baz.bar.com", Qtype: dns.TypeA}},
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MsgHdr: dns.MsgHdr{
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Id: 1,
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Rcode: dns.RcodeNameError,
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RecursionAvailable: false,
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Response: true,
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Opcode: dns.OpcodeQuery,
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Authoritative: true,
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}},
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},
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{
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name: "A record query, but the name is not a valid FQDN",
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ip4: map[dnsname.FQDN][]net.IP{dnsname.FQDN("foo.bar.com."): {{1, 2, 3, 4}}},
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query: &dns.Msg{
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Question: []dns.Question{{Name: "foo..bar.com", Qtype: dns.TypeA}},
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MsgHdr: dns.MsgHdr{Id: 1},
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},
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wantResp: &dns.Msg{
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Question: []dns.Question{{Name: "foo..bar.com", Qtype: dns.TypeA}},
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MsgHdr: dns.MsgHdr{
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Id: 1,
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Rcode: dns.RcodeFormatError,
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Response: true,
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Opcode: dns.OpcodeQuery,
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}},
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},
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{
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name: "AAAA record query, A record exists",
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ip4: map[dnsname.FQDN][]net.IP{dnsname.FQDN("foo.bar.com."): {{1, 2, 3, 4}}},
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query: &dns.Msg{
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Question: []dns.Question{{Name: "foo.bar.com", Qtype: dns.TypeAAAA}},
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MsgHdr: dns.MsgHdr{Id: 1},
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},
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wantResp: &dns.Msg{
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Question: []dns.Question{{Name: "foo.bar.com", Qtype: dns.TypeAAAA}},
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MsgHdr: dns.MsgHdr{
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Id: 1,
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Rcode: dns.RcodeSuccess,
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Response: true,
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Opcode: dns.OpcodeQuery,
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Authoritative: true,
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}},
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},
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{
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name: "AAAA record query, A record does not exist",
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ip4: map[dnsname.FQDN][]net.IP{dnsname.FQDN("foo.bar.com."): {{1, 2, 3, 4}}},
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query: &dns.Msg{
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Question: []dns.Question{{Name: "baz.bar.com", Qtype: dns.TypeAAAA}},
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MsgHdr: dns.MsgHdr{Id: 1},
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},
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wantResp: &dns.Msg{
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Question: []dns.Question{{Name: "baz.bar.com", Qtype: dns.TypeAAAA}},
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MsgHdr: dns.MsgHdr{
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Id: 1,
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Rcode: dns.RcodeNameError,
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Response: true,
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Opcode: dns.OpcodeQuery,
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Authoritative: true,
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}},
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},
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{
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name: "CNAME record query",
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ip4: map[dnsname.FQDN][]net.IP{dnsname.FQDN("foo.bar.com."): {{1, 2, 3, 4}}},
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query: &dns.Msg{
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Question: []dns.Question{{Name: "foo.bar.com", Qtype: dns.TypeCNAME}},
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MsgHdr: dns.MsgHdr{Id: 1},
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},
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wantResp: &dns.Msg{
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Question: []dns.Question{{Name: "foo.bar.com", Qtype: dns.TypeCNAME}},
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MsgHdr: dns.MsgHdr{
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Id: 1,
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Rcode: dns.RcodeNotImplemented,
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Response: true,
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Opcode: dns.OpcodeQuery,
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}},
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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ns := &nameserver{
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ip4: tt.ip4,
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}
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handler := ns.handleFunc()
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fakeRespW := &fakeResponseWriter{}
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handler(fakeRespW, tt.query)
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if diff := cmp.Diff(*fakeRespW.msg, *tt.wantResp); diff != "" {
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t.Fatalf("unexpected response (-got +want): \n%s", diff)
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}
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})
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}
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}
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func TestResetRecords(t *testing.T) {
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tests := []struct {
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name string
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config []byte
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hasIp4 map[dnsname.FQDN][]net.IP
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wantsIp4 map[dnsname.FQDN][]net.IP
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wantsErr bool
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}{
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{
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name: "previously empty nameserver.ip4 gets set",
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config: []byte(`{"version": "v1alpha1", "ip4": {"foo.bar.com": ["1.2.3.4"]}}`),
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wantsIp4: map[dnsname.FQDN][]net.IP{"foo.bar.com.": {{1, 2, 3, 4}}},
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},
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{
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name: "nameserver.ip4 gets reset",
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hasIp4: map[dnsname.FQDN][]net.IP{"baz.bar.com.": {{1, 1, 3, 3}}},
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config: []byte(`{"version": "v1alpha1", "ip4": {"foo.bar.com": ["1.2.3.4"]}}`),
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wantsIp4: map[dnsname.FQDN][]net.IP{"foo.bar.com.": {{1, 2, 3, 4}}},
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},
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{
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name: "configuration with incompatible version",
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hasIp4: map[dnsname.FQDN][]net.IP{"baz.bar.com.": {{1, 1, 3, 3}}},
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config: []byte(`{"version": "v1beta1", "ip4": {"foo.bar.com": ["1.2.3.4"]}}`),
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wantsIp4: map[dnsname.FQDN][]net.IP{"baz.bar.com.": {{1, 1, 3, 3}}},
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wantsErr: true,
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},
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{
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name: "nameserver.ip4 gets reset to empty config when no configuration is provided",
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hasIp4: map[dnsname.FQDN][]net.IP{"baz.bar.com.": {{1, 1, 3, 3}}},
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wantsIp4: make(map[dnsname.FQDN][]net.IP),
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},
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{
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name: "nameserver.ip4 gets reset to empty config when the provided configuration is empty",
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hasIp4: map[dnsname.FQDN][]net.IP{"baz.bar.com.": {{1, 1, 3, 3}}},
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config: []byte(`{"version": "v1alpha1", "ip4": {}}`),
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wantsIp4: make(map[dnsname.FQDN][]net.IP),
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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ns := &nameserver{
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ip4: tt.hasIp4,
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configReader: func() ([]byte, error) { return tt.config, nil },
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}
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if err := ns.resetRecords(); err == nil == tt.wantsErr {
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t.Errorf("resetRecords() returned err: %v, wantsErr: %v", err, tt.wantsErr)
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}
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if diff := cmp.Diff(ns.ip4, tt.wantsIp4); diff != "" {
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t.Fatalf("unexpected nameserver.ip4 contents (-got +want): \n%s", diff)
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}
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})
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}
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}
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// fakeResponseWriter is a faked out dns.ResponseWriter that can be used in
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// tests that need to read the response message that was written.
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type fakeResponseWriter struct {
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msg *dns.Msg
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}
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var _ dns.ResponseWriter = &fakeResponseWriter{}
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func (fr *fakeResponseWriter) WriteMsg(msg *dns.Msg) error {
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fr.msg = msg
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return nil
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}
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func (fr *fakeResponseWriter) LocalAddr() net.Addr {
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return nil
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}
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func (fr *fakeResponseWriter) RemoteAddr() net.Addr {
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return nil
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}
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func (fr *fakeResponseWriter) Write([]byte) (int, error) {
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return 0, nil
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}
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func (fr *fakeResponseWriter) Close() error {
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return nil
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}
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func (fr *fakeResponseWriter) TsigStatus() error {
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return nil
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}
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func (fr *fakeResponseWriter) TsigTimersOnly(bool) {}
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func (fr *fakeResponseWriter) Hijack() {}
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