// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package resolver import ( "bytes" "context" "encoding/hex" "encoding/json" "errors" "fmt" "math/rand" "net" "net/netip" "reflect" "runtime" "strconv" "strings" "testing" "time" miekdns "github.com/miekg/dns" "golang.org/x/net/dns/dnsmessage" dns "golang.org/x/net/dns/dnsmessage" "tailscale.com/net/netaddr" "tailscale.com/net/tsdial" "tailscale.com/tstest" "tailscale.com/types/dnstype" "tailscale.com/util/dnsname" "tailscale.com/wgengine/monitor" ) var ( testipv4 = netip.MustParseAddr("1.2.3.4") testipv6 = netip.MustParseAddr("0001:0203:0405:0607:0809:0a0b:0c0d:0e0f") testipv4Arpa = dnsname.FQDN("4.3.2.1.in-addr.arpa.") testipv6Arpa = dnsname.FQDN("f.0.e.0.d.0.c.0.b.0.a.0.9.0.8.0.7.0.6.0.5.0.4.0.3.0.2.0.1.0.0.0.ip6.arpa.") magicDNSv4Port = netip.MustParseAddrPort("100.100.100.100:53") ) var dnsCfg = Config{ Hosts: map[dnsname.FQDN][]netip.Addr{ "test1.ipn.dev.": {testipv4}, "test2.ipn.dev.": {testipv6}, }, LocalDomains: []dnsname.FQDN{"ipn.dev.", "3.2.1.in-addr.arpa.", "1.0.0.0.ip6.arpa."}, } const noEdns = 0 const dnsHeaderLen = 12 func dnspacket(domain dnsname.FQDN, tp dns.Type, ednsSize uint16) []byte { var dnsHeader dns.Header question := dns.Question{ Name: dns.MustNewName(domain.WithTrailingDot()), Type: tp, Class: dns.ClassINET, } builder := dns.NewBuilder(nil, dnsHeader) if err := builder.StartQuestions(); err != nil { panic(err) } if err := builder.Question(question); err != nil { panic(err) } if ednsSize != noEdns { if err := builder.StartAdditionals(); err != nil { panic(err) } ednsHeader := dns.ResourceHeader{ Name: dns.MustNewName("."), Type: dns.TypeOPT, Class: dns.Class(ednsSize), } if err := builder.OPTResource(ednsHeader, dns.OPTResource{}); err != nil { panic(err) } } payload, _ := builder.Finish() return payload } type dnsResponse struct { ip netip.Addr txt []string name dnsname.FQDN rcode dns.RCode truncated bool requestEdns bool requestEdnsSize uint16 responseEdns bool responseEdnsSize uint16 } func unpackResponse(payload []byte) (dnsResponse, error) { var response dnsResponse var parser dns.Parser h, err := parser.Start(payload) if err != nil { return response, err } if !h.Response { return response, errors.New("not a response") } response.rcode = h.RCode if response.rcode != dns.RCodeSuccess { return response, nil } response.truncated = h.Truncated if response.truncated { // TODO(#2067): Ideally, answer processing should still succeed when // dealing with a truncated message, but currently when we truncate // a packet, it's caused by the buffer being too small and usually that // means the data runs out mid-record. dns.Parser does not like it when // that happens. We can improve this by trimming off incomplete records. return response, nil } err = parser.SkipAllQuestions() if err != nil { return response, err } for { ah, err := parser.AnswerHeader() if err == dns.ErrSectionDone { break } if err != nil { return response, err } switch ah.Type { case dns.TypeA: res, err := parser.AResource() if err != nil { return response, err } response.ip = netaddr.IPv4(res.A[0], res.A[1], res.A[2], res.A[3]) case dns.TypeAAAA: res, err := parser.AAAAResource() if err != nil { return response, err } response.ip = netip.AddrFrom16(res.AAAA) case dns.TypeTXT: res, err := parser.TXTResource() if err != nil { return response, err } response.txt = res.TXT case dns.TypeNS: res, err := parser.NSResource() if err != nil { return response, err } response.name, err = dnsname.ToFQDN(res.NS.String()) if err != nil { return response, err } default: return response, errors.New("type not in {A, AAAA, NS}") } } err = parser.SkipAllAuthorities() if err != nil { return response, err } for { ah, err := parser.AdditionalHeader() if err == dns.ErrSectionDone { break } if err != nil { return response, err } switch ah.Type { case dns.TypeOPT: _, err := parser.OPTResource() if err != nil { return response, err } response.responseEdns = true response.responseEdnsSize = uint16(ah.Class) case dns.TypeTXT: res, err := parser.TXTResource() if err != nil { return response, err } switch ah.Name.String() { case "query-info.test.": for _, msg := range res.TXT { s := strings.SplitN(msg, "=", 2) if len(s) != 2 { continue } switch s[0] { case "EDNS": response.requestEdns, err = strconv.ParseBool(s[1]) if err != nil { return response, err } case "maxSize": sz, err := strconv.ParseUint(s[1], 10, 16) if err != nil { return response, err } response.requestEdnsSize = uint16(sz) } } } } } return response, nil } func syncRespond(r *Resolver, query []byte) ([]byte, error) { return r.Query(context.Background(), query, netip.AddrPort{}) } func mustIP(str string) netip.Addr { ip, err := netip.ParseAddr(str) if err != nil { panic(err) } return ip } func TestRDNSNameToIPv4(t *testing.T) { tests := []struct { name string input dnsname.FQDN wantIP netip.Addr wantOK bool }{ {"valid", "4.123.24.1.in-addr.arpa.", netaddr.IPv4(1, 24, 123, 4), true}, {"double_dot", "1..2.3.in-addr.arpa.", netip.Addr{}, false}, {"overflow", "1.256.3.4.in-addr.arpa.", netip.Addr{}, false}, {"not_ip", "sub.do.ma.in.in-addr.arpa.", netip.Addr{}, false}, } for _, tt := range tests { t.Run(tt.name, func(t *testing.T) { ip, ok := rdnsNameToIPv4(tt.input) if ok != tt.wantOK { t.Errorf("ok = %v; want %v", ok, tt.wantOK) } else if ok && ip != tt.wantIP { t.Errorf("ip = %v; want %v", ip, tt.wantIP) } }) } } func TestRDNSNameToIPv6(t *testing.T) { tests := []struct { name string input dnsname.FQDN wantIP netip.Addr wantOK bool }{ { "valid", "b.a.9.8.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.", mustIP("2001:db8::567:89ab"), true, }, { "double_dot", "b..9.8.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.", netip.Addr{}, false, }, { "double_hex", "b.a.98.0.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.", netip.Addr{}, false, }, { "not_hex", "b.a.g.0.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.", netip.Addr{}, false, }, } for _, tt := range tests { t.Run(tt.name, func(t *testing.T) { ip, ok := rdnsNameToIPv6(tt.input) if ok != tt.wantOK { t.Errorf("ok = %v; want %v", ok, tt.wantOK) } else if ok && ip != tt.wantIP { t.Errorf("ip = %v; want %v", ip, tt.wantIP) } }) } } func newResolver(t testing.TB) *Resolver { return New(t.Logf, nil /* no link monitor */, nil /* no link selector */, new(tsdial.Dialer)) } func TestResolveLocal(t *testing.T) { r := newResolver(t) defer r.Close() r.SetConfig(dnsCfg) tests := []struct { name string qname dnsname.FQDN qtype dns.Type ip netip.Addr code dns.RCode }{ {"ipv4", "test1.ipn.dev.", dns.TypeA, testipv4, dns.RCodeSuccess}, {"ipv6", "test2.ipn.dev.", dns.TypeAAAA, testipv6, dns.RCodeSuccess}, {"no-ipv6", "test1.ipn.dev.", dns.TypeAAAA, netip.Addr{}, dns.RCodeSuccess}, {"nxdomain", "test3.ipn.dev.", dns.TypeA, netip.Addr{}, dns.RCodeNameError}, {"foreign domain", "google.com.", dns.TypeA, netip.Addr{}, dns.RCodeRefused}, {"all", "test1.ipn.dev.", dns.TypeA, testipv4, dns.RCodeSuccess}, {"mx-ipv4", "test1.ipn.dev.", dns.TypeMX, netip.Addr{}, dns.RCodeSuccess}, {"mx-ipv6", "test2.ipn.dev.", dns.TypeMX, netip.Addr{}, dns.RCodeSuccess}, {"mx-nxdomain", "test3.ipn.dev.", dns.TypeMX, netip.Addr{}, dns.RCodeNameError}, {"ns-nxdomain", "test3.ipn.dev.", dns.TypeNS, netip.Addr{}, dns.RCodeNameError}, {"onion-domain", "footest.onion.", dns.TypeA, netip.Addr{}, dns.RCodeNameError}, {"magicdns", dnsSymbolicFQDN, dns.TypeA, netip.MustParseAddr("100.100.100.100"), dns.RCodeSuccess}, {"via_hex", dnsname.FQDN("via-0xff.1.2.3.4."), dns.TypeAAAA, netip.MustParseAddr("fd7a:115c:a1e0:b1a:0:ff:1.2.3.4"), dns.RCodeSuccess}, {"via_dec", dnsname.FQDN("via-1.10.0.0.1."), dns.TypeAAAA, netip.MustParseAddr("fd7a:115c:a1e0:b1a:0:1:10.0.0.1"), dns.RCodeSuccess}, {"x_via_hex", dnsname.FQDN("4.3.2.1.via-0xff."), dns.TypeAAAA, netip.MustParseAddr("fd7a:115c:a1e0:b1a:0:ff:4.3.2.1"), dns.RCodeSuccess}, {"x_via_dec", dnsname.FQDN("1.0.0.10.via-1."), dns.TypeAAAA, netip.MustParseAddr("fd7a:115c:a1e0:b1a:0:1:1.0.0.10"), dns.RCodeSuccess}, {"via_invalid", dnsname.FQDN("via-."), dns.TypeAAAA, netip.Addr{}, dns.RCodeRefused}, {"via_invalid_2", dnsname.FQDN("2.3.4.5.via-."), dns.TypeAAAA, netip.Addr{}, dns.RCodeRefused}, } for _, tt := range tests { t.Run(tt.name, func(t *testing.T) { ip, code := r.resolveLocal(tt.qname, tt.qtype) if code != tt.code { t.Errorf("code = %v; want %v", code, tt.code) } // Only check ip for non-err if ip != tt.ip { t.Errorf("ip = %v; want %v", ip, tt.ip) } }) } } func TestResolveLocalReverse(t *testing.T) { r := newResolver(t) defer r.Close() r.SetConfig(dnsCfg) tests := []struct { name string q dnsname.FQDN want dnsname.FQDN code dns.RCode }{ {"ipv4", testipv4Arpa, "test1.ipn.dev.", dns.RCodeSuccess}, {"ipv6", testipv6Arpa, "test2.ipn.dev.", dns.RCodeSuccess}, {"ipv4_nxdomain", dnsname.FQDN("5.3.2.1.in-addr.arpa."), "", dns.RCodeNameError}, {"ipv6_nxdomain", dnsname.FQDN("0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.0.ip6.arpa."), "", dns.RCodeNameError}, {"nxdomain", dnsname.FQDN("2.3.4.5.in-addr.arpa."), "", dns.RCodeRefused}, {"magicdns", dnsname.FQDN("100.100.100.100.in-addr.arpa."), dnsSymbolicFQDN, dns.RCodeSuccess}, {"ipv6_4to6", dnsname.FQDN("4.6.4.6.4.6.2.6.6.9.d.c.3.4.8.4.2.1.b.a.0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa."), dnsSymbolicFQDN, dns.RCodeSuccess}, } for _, tt := range tests { t.Run(tt.name, func(t *testing.T) { name, code := r.resolveLocalReverse(tt.q) if code != tt.code { t.Errorf("code = %v; want %v", code, tt.code) } if name != tt.want { t.Errorf("ip = %v; want %v", name, tt.want) } }) } } func ipv6Works() bool { c, err := net.Listen("tcp", "[::1]:0") if err != nil { return false } c.Close() return true } func generateTXT(size int, source rand.Source) []string { const sizePerTXT = 120 if size%2 != 0 { panic("even lengths only") } rng := rand.New(source) txts := make([]string, 0, size/sizePerTXT+1) raw := make([]byte, sizePerTXT/2) rem := size for ; rem > sizePerTXT; rem -= sizePerTXT { rng.Read(raw) txts = append(txts, hex.EncodeToString(raw)) } if rem > 0 { rng.Read(raw[:rem/2]) txts = append(txts, hex.EncodeToString(raw[:rem/2])) } return txts } func TestDelegate(t *testing.T) { tstest.ResourceCheck(t) if !ipv6Works() { t.Skip("skipping test that requires localhost IPv6") } randSource := rand.NewSource(4) // smallTXT does not require EDNS smallTXT := generateTXT(300, randSource) // medTXT and largeTXT are responses that require EDNS but we would like to // support these sizes of response without truncation because they are // moderately common. medTXT := generateTXT(1200, randSource) largeTXT := generateTXT(3900, randSource) // xlargeTXT is slightly above the maximum response size that we support, // so there should be truncation. xlargeTXT := generateTXT(5000, randSource) // hugeTXT is significantly larger than any typical MTU and will require // significant fragmentation. For buffer management reasons, we do not // intend to handle responses this large, so there should be truncation. hugeTXT := generateTXT(64000, randSource) records := []any{ "test.site.", resolveToIP(testipv4, testipv6, "dns.test.site."), "LCtesT.SiTe.", resolveToIPLowercase(testipv4, testipv6, "dns.test.site."), "nxdomain.site.", resolveToNXDOMAIN, "small.txt.", resolveToTXT(smallTXT, noEdns), "smalledns.txt.", resolveToTXT(smallTXT, 512), "med.txt.", resolveToTXT(medTXT, 1500), "large.txt.", resolveToTXT(largeTXT, maxResponseBytes), "xlarge.txt.", resolveToTXT(xlargeTXT, 8000), "huge.txt.", resolveToTXT(hugeTXT, 65527), } v4server := serveDNS(t, "127.0.0.1:0", records...) defer v4server.Shutdown() v6server := serveDNS(t, "[::1]:0", records...) defer v6server.Shutdown() r := newResolver(t) defer r.Close() cfg := dnsCfg cfg.Routes = map[dnsname.FQDN][]*dnstype.Resolver{ ".": { &dnstype.Resolver{Addr: v4server.PacketConn.LocalAddr().String()}, &dnstype.Resolver{Addr: v6server.PacketConn.LocalAddr().String()}, }, } r.SetConfig(cfg) tests := []struct { title string query []byte response dnsResponse }{ { "ipv4", dnspacket("test.site.", dns.TypeA, noEdns), dnsResponse{ip: testipv4, rcode: dns.RCodeSuccess}, }, { "ipv6", dnspacket("test.site.", dns.TypeAAAA, noEdns), dnsResponse{ip: testipv6, rcode: dns.RCodeSuccess}, }, { "ns", dnspacket("test.site.", dns.TypeNS, noEdns), dnsResponse{name: "dns.test.site.", rcode: dns.RCodeSuccess}, }, { "ipv4", dnspacket("LCtesT.SiTe.", dns.TypeA, noEdns), dnsResponse{ip: testipv4, rcode: dns.RCodeSuccess}, }, { "ipv6", dnspacket("LCtesT.SiTe.", dns.TypeAAAA, noEdns), dnsResponse{ip: testipv6, rcode: dns.RCodeSuccess}, }, { "ns", dnspacket("LCtesT.SiTe.", dns.TypeNS, noEdns), dnsResponse{name: "dns.test.site.", rcode: dns.RCodeSuccess}, }, { "nxdomain", dnspacket("nxdomain.site.", dns.TypeA, noEdns), dnsResponse{rcode: dns.RCodeNameError}, }, { "smalltxt", dnspacket("small.txt.", dns.TypeTXT, 8000), dnsResponse{txt: smallTXT, rcode: dns.RCodeSuccess, requestEdns: true, requestEdnsSize: maxResponseBytes}, }, { "smalltxtedns", dnspacket("smalledns.txt.", dns.TypeTXT, 512), dnsResponse{ txt: smallTXT, rcode: dns.RCodeSuccess, requestEdns: true, requestEdnsSize: 512, responseEdns: true, responseEdnsSize: 512, }, }, { "medtxt", dnspacket("med.txt.", dns.TypeTXT, 2000), dnsResponse{ txt: medTXT, rcode: dns.RCodeSuccess, requestEdns: true, requestEdnsSize: 2000, responseEdns: true, responseEdnsSize: 1500, }, }, { "largetxt", dnspacket("large.txt.", dns.TypeTXT, maxResponseBytes), dnsResponse{ txt: largeTXT, rcode: dns.RCodeSuccess, requestEdns: true, requestEdnsSize: maxResponseBytes, responseEdns: true, responseEdnsSize: maxResponseBytes, }, }, { "xlargetxt", dnspacket("xlarge.txt.", dns.TypeTXT, 8000), dnsResponse{ rcode: dns.RCodeSuccess, truncated: true, // request/response EDNS fields will be unset because of // they were truncated away }, }, { "hugetxt", dnspacket("huge.txt.", dns.TypeTXT, 8000), dnsResponse{ rcode: dns.RCodeSuccess, truncated: true, // request/response EDNS fields will be unset because of // they were truncated away }, }, } for _, tt := range tests { t.Run(tt.title, func(t *testing.T) { if tt.title == "hugetxt" && runtime.GOOS == "darwin" { t.Skip("known to not work on macOS: https://github.com/tailscale/tailscale/issues/2229") } payload, err := syncRespond(r, tt.query) if err != nil { t.Errorf("err = %v; want nil", err) return } response, err := unpackResponse(payload) if err != nil { t.Errorf("extract: err = %v; want nil (in %x)", err, payload) return } if response.rcode != tt.response.rcode { t.Errorf("rcode = %v; want %v", response.rcode, tt.response.rcode) } if response.ip != tt.response.ip { t.Errorf("ip = %v; want %v", response.ip, tt.response.ip) } if response.name != tt.response.name { t.Errorf("name = %v; want %v", response.name, tt.response.name) } if len(response.txt) != len(tt.response.txt) { t.Errorf("%v txt records, want %v txt records", len(response.txt), len(tt.response.txt)) } else { for i := range response.txt { if response.txt[i] != tt.response.txt[i] { t.Errorf("txt record %v is %s, want %s", i, response.txt[i], tt.response.txt[i]) } } } if response.requestEdns != tt.response.requestEdns { t.Errorf("requestEdns = %v; want %v", response.requestEdns, tt.response.requestEdns) } if response.requestEdnsSize != tt.response.requestEdnsSize { t.Errorf("requestEdnsSize = %v; want %v", response.requestEdnsSize, tt.response.requestEdnsSize) } if response.responseEdns != tt.response.responseEdns { t.Errorf("responseEdns = %v; want %v", response.requestEdns, tt.response.requestEdns) } if response.responseEdnsSize != tt.response.responseEdnsSize { t.Errorf("responseEdnsSize = %v; want %v", response.responseEdnsSize, tt.response.responseEdnsSize) } }) } } func TestDelegateSplitRoute(t *testing.T) { test4 := netip.MustParseAddr("2.3.4.5") test6 := netip.MustParseAddr("ff::1") server1 := serveDNS(t, "127.0.0.1:0", "test.site.", resolveToIP(testipv4, testipv6, "dns.test.site.")) defer server1.Shutdown() server2 := serveDNS(t, "127.0.0.1:0", "test.other.", resolveToIP(test4, test6, "dns.other.")) defer server2.Shutdown() r := newResolver(t) defer r.Close() cfg := dnsCfg cfg.Routes = map[dnsname.FQDN][]*dnstype.Resolver{ ".": {{Addr: server1.PacketConn.LocalAddr().String()}}, "other.": {{Addr: server2.PacketConn.LocalAddr().String()}}, } r.SetConfig(cfg) tests := []struct { title string query []byte response dnsResponse }{ { "general", dnspacket("test.site.", dns.TypeA, noEdns), dnsResponse{ip: testipv4, rcode: dns.RCodeSuccess}, }, { "override", dnspacket("test.other.", dns.TypeA, noEdns), dnsResponse{ip: test4, rcode: dns.RCodeSuccess}, }, } for _, tt := range tests { t.Run(tt.title, func(t *testing.T) { payload, err := syncRespond(r, tt.query) if err != nil { t.Errorf("err = %v; want nil", err) return } response, err := unpackResponse(payload) if err != nil { t.Errorf("extract: err = %v; want nil (in %x)", err, payload) return } if response.rcode != tt.response.rcode { t.Errorf("rcode = %v; want %v", response.rcode, tt.response.rcode) } if response.ip != tt.response.ip { t.Errorf("ip = %v; want %v", response.ip, tt.response.ip) } if response.name != tt.response.name { t.Errorf("name = %v; want %v", response.name, tt.response.name) } }) } } var allResponse = []byte{ 0x00, 0x00, // transaction id: 0 0x84, 0x00, // flags: response, authoritative, no error 0x00, 0x01, // one question 0x00, 0x01, // one answer 0x00, 0x00, 0x00, 0x00, // no authority or additional RRs // Question: 0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name 0x00, 0xff, 0x00, 0x01, // type ALL, class IN // Answer: 0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name 0x00, 0x01, 0x00, 0x01, // type A, class IN 0x00, 0x00, 0x02, 0x58, // TTL: 600 0x00, 0x04, // length: 4 bytes 0x01, 0x02, 0x03, 0x04, // A: 1.2.3.4 } var ipv4Response = []byte{ 0x00, 0x00, // transaction id: 0 0x84, 0x00, // flags: response, authoritative, no error 0x00, 0x01, // one question 0x00, 0x01, // one answer 0x00, 0x00, 0x00, 0x00, // no authority or additional RRs // Question: 0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name 0x00, 0x01, 0x00, 0x01, // type A, class IN // Answer: 0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name 0x00, 0x01, 0x00, 0x01, // type A, class IN 0x00, 0x00, 0x02, 0x58, // TTL: 600 0x00, 0x04, // length: 4 bytes 0x01, 0x02, 0x03, 0x04, // A: 1.2.3.4 } var ipv6Response = []byte{ 0x00, 0x00, // transaction id: 0 0x84, 0x00, // flags: response, authoritative, no error 0x00, 0x01, // one question 0x00, 0x01, // one answer 0x00, 0x00, 0x00, 0x00, // no authority or additional RRs // Question: 0x05, 0x74, 0x65, 0x73, 0x74, 0x32, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name 0x00, 0x1c, 0x00, 0x01, // type AAAA, class IN // Answer: 0x05, 0x74, 0x65, 0x73, 0x74, 0x32, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name 0x00, 0x1c, 0x00, 0x01, // type AAAA, class IN 0x00, 0x00, 0x02, 0x58, // TTL: 600 0x00, 0x10, // length: 16 bytes // AAAA: 0001:0203:0405:0607:0809:0A0B:0C0D:0E0F 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0xb, 0xc, 0xd, 0xe, 0xf, } var ipv4UppercaseResponse = []byte{ 0x00, 0x00, // transaction id: 0 0x84, 0x00, // flags: response, authoritative, no error 0x00, 0x01, // one question 0x00, 0x01, // one answer 0x00, 0x00, 0x00, 0x00, // no authority or additional RRs // Question: 0x05, 0x54, 0x45, 0x53, 0x54, 0x31, 0x03, 0x49, 0x50, 0x4e, 0x03, 0x44, 0x45, 0x56, 0x00, // name 0x00, 0x01, 0x00, 0x01, // type A, class IN // Answer: 0x05, 0x54, 0x45, 0x53, 0x54, 0x31, 0x03, 0x49, 0x50, 0x4e, 0x03, 0x44, 0x45, 0x56, 0x00, // name 0x00, 0x01, 0x00, 0x01, // type A, class IN 0x00, 0x00, 0x02, 0x58, // TTL: 600 0x00, 0x04, // length: 4 bytes 0x01, 0x02, 0x03, 0x04, // A: 1.2.3.4 } var ptrResponse = []byte{ 0x00, 0x00, // transaction id: 0 0x84, 0x00, // flags: response, authoritative, no error 0x00, 0x01, // one question 0x00, 0x01, // one answer 0x00, 0x00, 0x00, 0x00, // no authority or additional RRs // Question: 4.3.2.1.in-addr.arpa 0x01, 0x34, 0x01, 0x33, 0x01, 0x32, 0x01, 0x31, 0x07, 0x69, 0x6e, 0x2d, 0x61, 0x64, 0x64, 0x72, 0x04, 0x61, 0x72, 0x70, 0x61, 0x00, 0x00, 0x0c, 0x00, 0x01, // type PTR, class IN // Answer: 4.3.2.1.in-addr.arpa 0x01, 0x34, 0x01, 0x33, 0x01, 0x32, 0x01, 0x31, 0x07, 0x69, 0x6e, 0x2d, 0x61, 0x64, 0x64, 0x72, 0x04, 0x61, 0x72, 0x70, 0x61, 0x00, 0x00, 0x0c, 0x00, 0x01, // type PTR, class IN 0x00, 0x00, 0x02, 0x58, // TTL: 600 0x00, 0x0f, // length: 15 bytes // PTR: test1.ipn.dev 0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, } var ptrResponse6 = []byte{ 0x00, 0x00, // transaction id: 0 0x84, 0x00, // flags: response, authoritative, no error 0x00, 0x01, // one question 0x00, 0x01, // one answer 0x00, 0x00, 0x00, 0x00, // no authority or additional RRs // Question: f.0.e.0.d.0.c.0.b.0.a.0.9.0.8.0.7.0.6.0.5.0.4.0.3.0.2.0.1.0.0.0.ip6.arpa 0x01, 0x66, 0x01, 0x30, 0x01, 0x65, 0x01, 0x30, 0x01, 0x64, 0x01, 0x30, 0x01, 0x63, 0x01, 0x30, 0x01, 0x62, 0x01, 0x30, 0x01, 0x61, 0x01, 0x30, 0x01, 0x39, 0x01, 0x30, 0x01, 0x38, 0x01, 0x30, 0x01, 0x37, 0x01, 0x30, 0x01, 0x36, 0x01, 0x30, 0x01, 0x35, 0x01, 0x30, 0x01, 0x34, 0x01, 0x30, 0x01, 0x33, 0x01, 0x30, 0x01, 0x32, 0x01, 0x30, 0x01, 0x31, 0x01, 0x30, 0x01, 0x30, 0x01, 0x30, 0x03, 0x69, 0x70, 0x36, 0x04, 0x61, 0x72, 0x70, 0x61, 0x00, 0x00, 0x0c, 0x00, 0x01, // type PTR, class IN6 // Answer: f.0.e.0.d.0.c.0.b.0.a.0.9.0.8.0.7.0.6.0.5.0.4.0.3.0.2.0.1.0.0.0.ip6.arpa 0x01, 0x66, 0x01, 0x30, 0x01, 0x65, 0x01, 0x30, 0x01, 0x64, 0x01, 0x30, 0x01, 0x63, 0x01, 0x30, 0x01, 0x62, 0x01, 0x30, 0x01, 0x61, 0x01, 0x30, 0x01, 0x39, 0x01, 0x30, 0x01, 0x38, 0x01, 0x30, 0x01, 0x37, 0x01, 0x30, 0x01, 0x36, 0x01, 0x30, 0x01, 0x35, 0x01, 0x30, 0x01, 0x34, 0x01, 0x30, 0x01, 0x33, 0x01, 0x30, 0x01, 0x32, 0x01, 0x30, 0x01, 0x31, 0x01, 0x30, 0x01, 0x30, 0x01, 0x30, 0x03, 0x69, 0x70, 0x36, 0x04, 0x61, 0x72, 0x70, 0x61, 0x00, 0x00, 0x0c, 0x00, 0x01, // type PTR, class IN 0x00, 0x00, 0x02, 0x58, // TTL: 600 0x00, 0x0f, // length: 15 bytes // PTR: test2.ipn.dev 0x05, 0x74, 0x65, 0x73, 0x74, 0x32, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, } var nxdomainResponse = []byte{ 0x00, 0x00, // transaction id: 0 0x84, 0x03, // flags: response, authoritative, error: nxdomain 0x00, 0x01, // one question 0x00, 0x00, // no answers 0x00, 0x00, 0x00, 0x00, // no authority or additional RRs // Question: 0x05, 0x74, 0x65, 0x73, 0x74, 0x33, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name 0x00, 0x01, 0x00, 0x01, // type A, class IN } var emptyResponse = []byte{ 0x00, 0x00, // transaction id: 0 0x84, 0x00, // flags: response, authoritative, no error 0x00, 0x01, // one question 0x00, 0x00, // no answers 0x00, 0x00, 0x00, 0x00, // no authority or additional RRs // Question: 0x05, 0x74, 0x65, 0x73, 0x74, 0x31, 0x03, 0x69, 0x70, 0x6e, 0x03, 0x64, 0x65, 0x76, 0x00, // name 0x00, 0x1c, 0x00, 0x01, // type AAAA, class IN } func TestFull(t *testing.T) { r := newResolver(t) defer r.Close() r.SetConfig(dnsCfg) // One full packet and one error packet tests := []struct { name string request []byte response []byte }{ {"all", dnspacket("test1.ipn.dev.", dns.TypeALL, noEdns), allResponse}, {"ipv4", dnspacket("test1.ipn.dev.", dns.TypeA, noEdns), ipv4Response}, {"ipv6", dnspacket("test2.ipn.dev.", dns.TypeAAAA, noEdns), ipv6Response}, {"no-ipv6", dnspacket("test1.ipn.dev.", dns.TypeAAAA, noEdns), emptyResponse}, {"upper", dnspacket("TEST1.IPN.DEV.", dns.TypeA, noEdns), ipv4UppercaseResponse}, {"ptr4", dnspacket("4.3.2.1.in-addr.arpa.", dns.TypePTR, noEdns), ptrResponse}, {"ptr6", dnspacket("f.0.e.0.d.0.c.0.b.0.a.0.9.0.8.0.7.0.6.0.5.0.4.0.3.0.2.0.1.0.0.0.ip6.arpa.", dns.TypePTR, noEdns), ptrResponse6}, {"nxdomain", dnspacket("test3.ipn.dev.", dns.TypeA, noEdns), nxdomainResponse}, } for _, tt := range tests { t.Run(tt.name, func(t *testing.T) { response, err := syncRespond(r, tt.request) if err != nil { t.Errorf("err = %v; want nil", err) } if !bytes.Equal(response, tt.response) { t.Errorf("response = %x; want %x", response, tt.response) } }) } } func TestAllocs(t *testing.T) { r := newResolver(t) defer r.Close() r.SetConfig(dnsCfg) // It is seemingly pointless to test allocs in the delegate path, // as dialer.Dial -> Read -> Write alone comprise 12 allocs. tests := []struct { name string query []byte want uint64 }{ // Name lowercasing, response slice created by dns.NewBuilder, // and closure allocation from go call. {"forward", dnspacket("test1.ipn.dev.", dns.TypeA, noEdns), 3}, // 3 extra allocs in rdnsNameToIPv4 and one in marshalPTRRecord (dns.NewName). {"reverse", dnspacket("4.3.2.1.in-addr.arpa.", dns.TypePTR, noEdns), 5}, } for _, tt := range tests { err := tstest.MinAllocsPerRun(t, tt.want, func() { syncRespond(r, tt.query) }) if err != nil { t.Errorf("%s: %v", tt.name, err) } } } func TestTrimRDNSBonjourPrefix(t *testing.T) { tests := []struct { in dnsname.FQDN want bool }{ {"b._dns-sd._udp.0.10.20.172.in-addr.arpa.", true}, {"db._dns-sd._udp.0.10.20.172.in-addr.arpa.", true}, {"r._dns-sd._udp.0.10.20.172.in-addr.arpa.", true}, {"dr._dns-sd._udp.0.10.20.172.in-addr.arpa.", true}, {"lb._dns-sd._udp.0.10.20.172.in-addr.arpa.", true}, {"qq._dns-sd._udp.0.10.20.172.in-addr.arpa.", false}, {"0.10.20.172.in-addr.arpa.", false}, {"lb._dns-sd._udp.ts-dns.test.", true}, } for _, test := range tests { got := hasRDNSBonjourPrefix(test.in) if got != test.want { t.Errorf("trimRDNSBonjourPrefix(%q) = %v, want %v", test.in, got, test.want) } } } func BenchmarkFull(b *testing.B) { server := serveDNS(b, "127.0.0.1:0", "test.site.", resolveToIP(testipv4, testipv6, "dns.test.site.")) defer server.Shutdown() r := newResolver(b) defer r.Close() cfg := dnsCfg cfg.Routes = map[dnsname.FQDN][]*dnstype.Resolver{ ".": {{Addr: server.PacketConn.LocalAddr().String()}}, } tests := []struct { name string request []byte }{ {"forward", dnspacket("test1.ipn.dev.", dns.TypeA, noEdns)}, {"reverse", dnspacket("4.3.2.1.in-addr.arpa.", dns.TypePTR, noEdns)}, {"delegated", dnspacket("test.site.", dns.TypeA, noEdns)}, } for _, tt := range tests { b.Run(tt.name, func(b *testing.B) { b.ReportAllocs() for i := 0; i < b.N; i++ { syncRespond(r, tt.request) } }) } } func TestMarshalResponseFormatError(t *testing.T) { resp := new(response) resp.Header.RCode = dns.RCodeFormatError v, err := marshalResponse(resp) if err != nil { t.Errorf("marshal error: %v", err) } t.Logf("response: %q", v) } func TestForwardLinkSelection(t *testing.T) { old := initListenConfig defer func() { initListenConfig = old }() configCall := make(chan string, 1) initListenConfig = func(nc *net.ListenConfig, mon *monitor.Mon, tunName string) error { select { case configCall <- tunName: return nil default: t.Error("buffer full") return errors.New("buffer full") } } // specialIP is some IP we pretend that our link selector // routes differently. specialIP := netaddr.IPv4(1, 2, 3, 4) fwd := newForwarder(t.Logf, nil, linkSelFunc(func(ip netip.Addr) string { if ip == netaddr.IPv4(1, 2, 3, 4) { return "special" } return "" }), new(tsdial.Dialer)) // Test non-special IP. if got, err := fwd.packetListener(netip.Addr{}); err != nil { t.Fatal(err) } else if got != stdNetPacketListener { t.Errorf("for IP zero value, didn't get expected packet listener") } select { case v := <-configCall: t.Errorf("unexpected ListenConfig call, with tunName %q", v) default: } // Test that our special IP generates a call to initListenConfig. if got, err := fwd.packetListener(specialIP); err != nil { t.Fatal(err) } else if got == stdNetPacketListener { t.Errorf("special IP returned std packet listener; expected unique one") } if v, ok := <-configCall; !ok { t.Errorf("didn't get ListenConfig call") } else if v != "special" { t.Errorf("got tunName %q; want 'special'", v) } } type linkSelFunc func(ip netip.Addr) string func (f linkSelFunc) PickLink(ip netip.Addr) 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 := []any{ "no-records.test.", dnsHandler(), "one-a.test.", dnsHandler(netip.MustParseAddr("1.2.3.4")), "two-a.test.", dnsHandler(netip.MustParseAddr("1.2.3.4"), netip.MustParseAddr("5.6.7.8")), "one-aaaa.test.", dnsHandler(netip.MustParseAddr("1::2")), "two-aaaa.test.", dnsHandler(netip.MustParseAddr("1::2"), netip.MustParseAddr("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) } } } // TestServfail validates that a SERVFAIL error response is returned if // all upstream resolvers respond with SERVFAIL. // // See: https://github.com/tailscale/tailscale/issues/4722 func TestServfail(t *testing.T) { server := serveDNS(t, "127.0.0.1:0", "test.site.", miekdns.HandlerFunc(func(w miekdns.ResponseWriter, req *miekdns.Msg) { m := new(miekdns.Msg) m.Rcode = miekdns.RcodeServerFailure w.WriteMsg(m) })) defer server.Shutdown() r := newResolver(t) defer r.Close() cfg := dnsCfg cfg.Routes = map[dnsname.FQDN][]*dnstype.Resolver{ ".": {{Addr: server.PacketConn.LocalAddr().String()}}, } r.SetConfig(cfg) pkt, err := syncRespond(r, dnspacket("test.site.", dns.TypeA, noEdns)) if err != errServerFailure { t.Errorf("err = %v, want %v", err, errServerFailure) } wantPkt := []byte{ 0x00, 0x00, // transaction id: 0 0x84, 0x02, // flags: response, authoritative, error: servfail 0x00, 0x01, // one question 0x00, 0x00, // no answers 0x00, 0x00, 0x00, 0x00, // no authority or additional RRs // Question: 0x04, 0x74, 0x65, 0x73, 0x74, 0x04, 0x73, 0x69, 0x74, 0x65, 0x00, // name 0x00, 0x01, 0x00, 0x01, // type A, class IN } if !bytes.Equal(pkt, wantPkt) { t.Errorf("response was %X, want %X", pkt, wantPkt) } }