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tailscale/net/dns/resolver/tsdns_server_test.go

335 lines
7.6 KiB
Go

// 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 (
"fmt"
"net"
"strings"
"testing"
"github.com/miekg/dns"
"inet.af/netaddr"
)
// This file exists to isolate the test infrastructure
// that depends on github.com/miekg/dns
// from the rest, which only depends on dnsmessage.
// resolveToIP returns a handler function which responds
// to queries of type A it receives with an A record containing ipv4,
// to queries of type AAAA with an AAAA record containing ipv6,
// to queries of type NS with an NS record containing name.
func resolveToIP(ipv4, ipv6 netaddr.IP, ns string) 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")
}
question := req.Question[0]
var ans dns.RR
switch question.Qtype {
case dns.TypeA:
ans = &dns.A{
Hdr: dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
},
A: ipv4.IPAddr().IP,
}
case dns.TypeAAAA:
ans = &dns.AAAA{
Hdr: dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeAAAA,
Class: dns.ClassINET,
},
AAAA: ipv6.IPAddr().IP,
}
case dns.TypeNS:
ans = &dns.NS{
Hdr: dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeNS,
Class: dns.ClassINET,
},
Ns: ns,
}
}
m.Answer = append(m.Answer, ans)
w.WriteMsg(m)
}
}
// resolveToIPLowercase returns a handler function which canonicalizes responses
// by lowercasing the question and answer names, and responds
// to queries of type A it receives with an A record containing ipv4,
// to queries of type AAAA with an AAAA record containing ipv6,
// to queries of type NS with an NS record containing name.
func resolveToIPLowercase(ipv4, ipv6 netaddr.IP, ns string) 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.Question[0].Name = strings.ToLower(m.Question[0].Name)
question := req.Question[0]
var ans dns.RR
switch question.Qtype {
case dns.TypeA:
ans = &dns.A{
Hdr: dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
},
A: ipv4.IPAddr().IP,
}
case dns.TypeAAAA:
ans = &dns.AAAA{
Hdr: dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeAAAA,
Class: dns.ClassINET,
},
AAAA: ipv6.IPAddr().IP,
}
case dns.TypeNS:
ans = &dns.NS{
Hdr: dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeNS,
Class: dns.ClassINET,
},
Ns: ns,
}
}
m.Answer = append(m.Answer, ans)
w.WriteMsg(m)
}
}
// resolveToTXT returns a handler function which responds to queries of type TXT
// it receives with the strings in txts.
func resolveToTXT(txts []string, ednsMaxSize uint16) 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")
}
question := req.Question[0]
if question.Qtype != dns.TypeTXT {
w.WriteMsg(m)
return
}
ans := &dns.TXT{
Hdr: dns.RR_Header{
Name: question.Name,
Rrtype: dns.TypeTXT,
Class: dns.ClassINET,
},
Txt: txts,
}
m.Answer = append(m.Answer, ans)
queryInfo := &dns.TXT{
Hdr: dns.RR_Header{
Name: "query-info.test.",
Rrtype: dns.TypeTXT,
Class: dns.ClassINET,
},
}
if edns := req.IsEdns0(); edns == nil {
queryInfo.Txt = []string{"EDNS=false"}
} else {
queryInfo.Txt = []string{"EDNS=true", fmt.Sprintf("maxSize=%v", edns.UDPSize())}
}
m.Extra = append(m.Extra, queryInfo)
if ednsMaxSize > 0 {
m.SetEdns0(ednsMaxSize, false)
}
if err := w.WriteMsg(m); err != nil {
panic(err)
}
}
}
var resolveToNXDOMAIN = dns.HandlerFunc(func(w dns.ResponseWriter, req *dns.Msg) {
m := new(dns.Msg)
m.SetRcode(req, dns.RcodeNameError)
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 ...any) 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 ...any) *dns.Server {
if len(records)%2 != 0 {
panic("must have an even number of record values")
}
mux := dns.NewServeMux()
for i := 0; i < len(records); i += 2 {
name := records[i].(string)
handler := records[i+1].(dns.Handler)
mux.Handle(name, handler)
}
waitch := make(chan struct{})
server := &dns.Server{
Addr: addr,
Net: "udp",
Handler: mux,
NotifyStartedFunc: func() { close(waitch) },
ReusePort: true,
}
go func() {
err := server.ListenAndServe()
if err != nil {
panic(fmt.Sprintf("ListenAndServe(%q): %v", addr, err))
}
}()
<-waitch
return server
}