// Copyright 2009 The Go 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 net import ( "context" "errors" "fmt" "internal/testenv" "net/netip" "reflect" "runtime" "slices" "strings" "sync" "sync/atomic" "testing" "time" ) var goResolver = Resolver{PreferGo: true} func hasSuffixFold(s, suffix string) bool { return strings.HasSuffix(strings.ToLower(s), strings.ToLower(suffix)) } func lookupLocalhost(ctx context.Context, fn func(context.Context, string, string) ([]IPAddr, error), network, host string) ([]IPAddr, error) { switch host { case "localhost": return []IPAddr{ {IP: IPv4(127, 0, 0, 1)}, {IP: IPv6loopback}, }, nil default: return fn(ctx, network, host) } } // The Lookup APIs use various sources such as local database, DNS or // mDNS, and may use platform-dependent DNS stub resolver if possible. // The APIs accept any of forms for a query; host name in various // encodings, UTF-8 encoded net name, domain name, FQDN or absolute // FQDN, but the result would be one of the forms and it depends on // the circumstances. var lookupGoogleSRVTests = []struct { service, proto, name string cname, target string }{ { "ldap", "tcp", "google.com", "google.com.", "google.com.", }, { "ldap", "tcp", "google.com.", "google.com.", "google.com.", }, // non-standard back door { "", "", "_ldap._tcp.google.com", "google.com.", "google.com.", }, { "", "", "_ldap._tcp.google.com.", "google.com.", "google.com.", }, } var backoffDuration = [...]time.Duration{time.Second, 5 * time.Second, 30 * time.Second} func TestLookupGoogleSRV(t *testing.T) { t.Parallel() mustHaveExternalNetwork(t) if runtime.GOOS == "ios" { t.Skip("no resolv.conf on iOS") } if !supportsIPv4() || !*testIPv4 { t.Skip("IPv4 is required") } attempts := 0 for i := 0; i < len(lookupGoogleSRVTests); i++ { tt := lookupGoogleSRVTests[i] cname, srvs, err := LookupSRV(tt.service, tt.proto, tt.name) if err != nil { testenv.SkipFlakyNet(t) if attempts < len(backoffDuration) { dur := backoffDuration[attempts] t.Logf("backoff %v after failure %v\n", dur, err) time.Sleep(dur) attempts++ i-- continue } t.Fatal(err) } if len(srvs) == 0 { t.Error("got no record") } if !hasSuffixFold(cname, tt.cname) { t.Errorf("got %s; want %s", cname, tt.cname) } for _, srv := range srvs { if !hasSuffixFold(srv.Target, tt.target) { t.Errorf("got %v; want a record containing %s", srv, tt.target) } } } } var lookupGmailMXTests = []struct { name, host string }{ {"gmail.com", "google.com."}, {"gmail.com.", "google.com."}, } func TestLookupGmailMX(t *testing.T) { t.Parallel() mustHaveExternalNetwork(t) if runtime.GOOS == "ios" { t.Skip("no resolv.conf on iOS") } if !supportsIPv4() || !*testIPv4 { t.Skip("IPv4 is required") } attempts := 0 for i := 0; i < len(lookupGmailMXTests); i++ { tt := lookupGmailMXTests[i] mxs, err := LookupMX(tt.name) if err != nil { testenv.SkipFlakyNet(t) if attempts < len(backoffDuration) { dur := backoffDuration[attempts] t.Logf("backoff %v after failure %v\n", dur, err) time.Sleep(dur) attempts++ i-- continue } t.Fatal(err) } if len(mxs) == 0 { t.Error("got no record") } for _, mx := range mxs { if !hasSuffixFold(mx.Host, tt.host) { t.Errorf("got %v; want a record containing %s", mx, tt.host) } } } } var lookupGmailNSTests = []struct { name, host string }{ {"gmail.com", "google.com."}, {"gmail.com.", "google.com."}, } func TestLookupGmailNS(t *testing.T) { t.Parallel() mustHaveExternalNetwork(t) if runtime.GOOS == "ios" { t.Skip("no resolv.conf on iOS") } if !supportsIPv4() || !*testIPv4 { t.Skip("IPv4 is required") } attempts := 0 for i := 0; i < len(lookupGmailNSTests); i++ { tt := lookupGmailNSTests[i] nss, err := LookupNS(tt.name) if err != nil { testenv.SkipFlakyNet(t) if attempts < len(backoffDuration) { dur := backoffDuration[attempts] t.Logf("backoff %v after failure %v\n", dur, err) time.Sleep(dur) attempts++ i-- continue } t.Fatal(err) } if len(nss) == 0 { t.Error("got no record") } for _, ns := range nss { if !hasSuffixFold(ns.Host, tt.host) { t.Errorf("got %v; want a record containing %s", ns, tt.host) } } } } var lookupGmailTXTTests = []struct { name, txt, host string }{ {"gmail.com", "spf", "google.com"}, {"gmail.com.", "spf", "google.com"}, } func TestLookupGmailTXT(t *testing.T) { if runtime.GOOS == "plan9" { t.Skip("skipping on plan9; see https://golang.org/issue/29722") } t.Parallel() mustHaveExternalNetwork(t) if runtime.GOOS == "ios" { t.Skip("no resolv.conf on iOS") } if !supportsIPv4() || !*testIPv4 { t.Skip("IPv4 is required") } attempts := 0 for i := 0; i < len(lookupGmailTXTTests); i++ { tt := lookupGmailTXTTests[i] txts, err := LookupTXT(tt.name) if err != nil { testenv.SkipFlakyNet(t) if attempts < len(backoffDuration) { dur := backoffDuration[attempts] t.Logf("backoff %v after failure %v\n", dur, err) time.Sleep(dur) attempts++ i-- continue } t.Fatal(err) } if len(txts) == 0 { t.Error("got no record") } found := false for _, txt := range txts { if strings.Contains(txt, tt.txt) && (strings.HasSuffix(txt, tt.host) || strings.HasSuffix(txt, tt.host+".")) { found = true break } } if !found { t.Errorf("got %v; want a record containing %s, %s", txts, tt.txt, tt.host) } } } var lookupGooglePublicDNSAddrTests = []string{ "8.8.8.8", "8.8.4.4", "2001:4860:4860::8888", "2001:4860:4860::8844", } func TestLookupGooglePublicDNSAddr(t *testing.T) { mustHaveExternalNetwork(t) if !supportsIPv4() || !supportsIPv6() || !*testIPv4 || !*testIPv6 { t.Skip("both IPv4 and IPv6 are required") } defer dnsWaitGroup.Wait() for _, ip := range lookupGooglePublicDNSAddrTests { names, err := LookupAddr(ip) if err != nil { t.Fatal(err) } if len(names) == 0 { t.Error("got no record") } for _, name := range names { if !hasSuffixFold(name, ".google.com.") && !hasSuffixFold(name, ".google.") { t.Errorf("got %q; want a record ending in .google.com. or .google.", name) } } } } func TestLookupIPv6LinkLocalAddr(t *testing.T) { if !supportsIPv6() || !*testIPv6 { t.Skip("IPv6 is required") } defer dnsWaitGroup.Wait() addrs, err := LookupHost("localhost") if err != nil { t.Fatal(err) } found := false for _, addr := range addrs { if addr == "fe80::1%lo0" { found = true break } } if !found { t.Skipf("not supported on %s", runtime.GOOS) } if _, err := LookupAddr("fe80::1%lo0"); err != nil { t.Error(err) } } func TestLookupIPv6LinkLocalAddrWithZone(t *testing.T) { if !supportsIPv6() || !*testIPv6 { t.Skip("IPv6 is required") } ipaddrs, err := DefaultResolver.LookupIPAddr(context.Background(), "fe80::1%lo0") if err != nil { t.Error(err) } for _, addr := range ipaddrs { if e, a := "lo0", addr.Zone; e != a { t.Errorf("wrong zone: want %q, got %q", e, a) } } addrs, err := DefaultResolver.LookupHost(context.Background(), "fe80::1%lo0") if err != nil { t.Error(err) } for _, addr := range addrs { if e, a := "fe80::1%lo0", addr; e != a { t.Errorf("wrong host: want %q got %q", e, a) } } } var lookupCNAMETests = []struct { name, cname string }{ {"www.iana.org", "icann.org."}, {"www.iana.org.", "icann.org."}, {"www.google.com", "google.com."}, {"google.com", "google.com."}, {"cname-to-txt.go4.org", "test-txt-record.go4.org."}, } func TestLookupCNAME(t *testing.T) { mustHaveExternalNetwork(t) testenv.SkipFlakyNet(t) if !supportsIPv4() || !*testIPv4 { t.Skip("IPv4 is required") } defer dnsWaitGroup.Wait() attempts := 0 for i := 0; i < len(lookupCNAMETests); i++ { tt := lookupCNAMETests[i] cname, err := LookupCNAME(tt.name) if err != nil { testenv.SkipFlakyNet(t) if attempts < len(backoffDuration) { dur := backoffDuration[attempts] t.Logf("backoff %v after failure %v\n", dur, err) time.Sleep(dur) attempts++ i-- continue } t.Fatal(err) } if !hasSuffixFold(cname, tt.cname) { t.Errorf("got %s; want a record containing %s", cname, tt.cname) } } } var lookupGoogleHostTests = []struct { name string }{ {"google.com"}, {"google.com."}, } func TestLookupGoogleHost(t *testing.T) { mustHaveExternalNetwork(t) testenv.SkipFlakyNet(t) if !supportsIPv4() || !*testIPv4 { t.Skip("IPv4 is required") } defer dnsWaitGroup.Wait() for _, tt := range lookupGoogleHostTests { addrs, err := LookupHost(tt.name) if err != nil { t.Fatal(err) } if len(addrs) == 0 { t.Error("got no record") } for _, addr := range addrs { if ParseIP(addr) == nil { t.Errorf("got %q; want a literal IP address", addr) } } } } func TestLookupLongTXT(t *testing.T) { testenv.SkipFlaky(t, 22857) mustHaveExternalNetwork(t) defer dnsWaitGroup.Wait() txts, err := LookupTXT("golang.rsc.io") if err != nil { t.Fatal(err) } slices.Sort(txts) want := []string{ strings.Repeat("abcdefghijklmnopqrstuvwxyABCDEFGHJIKLMNOPQRSTUVWXY", 10), "gophers rule", } if !reflect.DeepEqual(txts, want) { t.Fatalf("LookupTXT golang.rsc.io incorrect\nhave %q\nwant %q", txts, want) } } var lookupGoogleIPTests = []struct { name string }{ {"google.com"}, {"google.com."}, } func TestLookupGoogleIP(t *testing.T) { mustHaveExternalNetwork(t) testenv.SkipFlakyNet(t) if !supportsIPv4() || !*testIPv4 { t.Skip("IPv4 is required") } defer dnsWaitGroup.Wait() for _, tt := range lookupGoogleIPTests { ips, err := LookupIP(tt.name) if err != nil { t.Fatal(err) } if len(ips) == 0 { t.Error("got no record") } for _, ip := range ips { if ip.To4() == nil && ip.To16() == nil { t.Errorf("got %v; want an IP address", ip) } } } } var revAddrTests = []struct { Addr string Reverse string ErrPrefix string }{ {"1.2.3.4", "4.3.2.1.in-addr.arpa.", ""}, {"245.110.36.114", "114.36.110.245.in-addr.arpa.", ""}, {"::ffff:12.34.56.78", "78.56.34.12.in-addr.arpa.", ""}, {"::1", "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa.", ""}, {"1::", "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.", ""}, {"1234:567::89a:bcde", "e.d.c.b.a.9.8.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.7.6.5.0.4.3.2.1.ip6.arpa.", ""}, {"1234:567:fefe:bcbc:adad:9e4a:89a:bcde", "e.d.c.b.a.9.8.0.a.4.e.9.d.a.d.a.c.b.c.b.e.f.e.f.7.6.5.0.4.3.2.1.ip6.arpa.", ""}, {"1.2.3", "", "unrecognized address"}, {"1.2.3.4.5", "", "unrecognized address"}, {"1234:567:bcbca::89a:bcde", "", "unrecognized address"}, {"1234:567::bcbc:adad::89a:bcde", "", "unrecognized address"}, } func TestReverseAddress(t *testing.T) { defer dnsWaitGroup.Wait() for i, tt := range revAddrTests { a, err := reverseaddr(tt.Addr) if len(tt.ErrPrefix) > 0 && err == nil { t.Errorf("#%d: expected %q, got (error)", i, tt.ErrPrefix) continue } if len(tt.ErrPrefix) == 0 && err != nil { t.Errorf("#%d: expected , got %q (error)", i, err) } if err != nil && err.(*DNSError).Err != tt.ErrPrefix { t.Errorf("#%d: expected %q, got %q (mismatched error)", i, tt.ErrPrefix, err.(*DNSError).Err) } if a != tt.Reverse { t.Errorf("#%d: expected %q, got %q (reverse address)", i, tt.Reverse, a) } } } func TestDNSFlood(t *testing.T) { if !*testDNSFlood { t.Skip("test disabled; use -dnsflood to enable") } defer dnsWaitGroup.Wait() var N = 5000 if runtime.GOOS == "darwin" || runtime.GOOS == "ios" { // On Darwin this test consumes kernel threads much // than other platforms for some reason. // When we monitor the number of allocated Ms by // observing on runtime.newm calls, we can see that it // easily reaches the per process ceiling // kern.num_threads when CGO_ENABLED=1 and // GODEBUG=netdns=go. N = 500 } const timeout = 3 * time.Second ctxHalfTimeout, cancel := context.WithTimeout(context.Background(), timeout/2) defer cancel() ctxTimeout, cancel := context.WithTimeout(context.Background(), timeout) defer cancel() c := make(chan error, 2*N) for i := 0; i < N; i++ { name := fmt.Sprintf("%d.net-test.golang.org", i) go func() { _, err := DefaultResolver.LookupIPAddr(ctxHalfTimeout, name) c <- err }() go func() { _, err := DefaultResolver.LookupIPAddr(ctxTimeout, name) c <- err }() } qstats := struct { succeeded, failed int timeout, temporary, other int unknown int }{} deadline := time.After(timeout + time.Second) for i := 0; i < 2*N; i++ { select { case <-deadline: t.Fatal("deadline exceeded") case err := <-c: switch err := err.(type) { case nil: qstats.succeeded++ case Error: qstats.failed++ if err.Timeout() { qstats.timeout++ } if err.Temporary() { qstats.temporary++ } if !err.Timeout() && !err.Temporary() { qstats.other++ } default: qstats.failed++ qstats.unknown++ } } } // A high volume of DNS queries for sub-domain of golang.org // would be coordinated by authoritative or recursive server, // or stub resolver which implements query-response rate // limitation, so we can expect some query successes and more // failures including timeout, temporary and other here. // As a rule, unknown must not be shown but it might possibly // happen due to issue 4856 for now. t.Logf("%v succeeded, %v failed (%v timeout, %v temporary, %v other, %v unknown)", qstats.succeeded, qstats.failed, qstats.timeout, qstats.temporary, qstats.other, qstats.unknown) } func TestLookupDotsWithLocalSource(t *testing.T) { if !supportsIPv4() || !*testIPv4 { t.Skip("IPv4 is required") } mustHaveExternalNetwork(t) defer dnsWaitGroup.Wait() for i, fn := range []func() func(){forceGoDNS, forceCgoDNS} { fixup := fn() if fixup == nil { continue } names, err := LookupAddr("127.0.0.1") fixup() if err != nil { t.Logf("#%d: %v", i, err) continue } mode := "netgo" if i == 1 { mode = "netcgo" } loop: for i, name := range names { if strings.Index(name, ".") == len(name)-1 { // "localhost" not "localhost." for j := range names { if j == i { continue } if names[j] == name[:len(name)-1] { // It's OK if we find the name without the dot, // as some systems say 127.0.0.1 localhost localhost. continue loop } } t.Errorf("%s: got %s; want %s", mode, name, name[:len(name)-1]) } else if strings.Contains(name, ".") && !strings.HasSuffix(name, ".") { // "localhost.localdomain." not "localhost.localdomain" t.Errorf("%s: got %s; want name ending with trailing dot", mode, name) } } } } func TestLookupDotsWithRemoteSource(t *testing.T) { if runtime.GOOS == "darwin" || runtime.GOOS == "ios" { testenv.SkipFlaky(t, 27992) } mustHaveExternalNetwork(t) testenv.SkipFlakyNet(t) if !supportsIPv4() || !*testIPv4 { t.Skip("IPv4 is required") } if runtime.GOOS == "ios" { t.Skip("no resolv.conf on iOS") } defer dnsWaitGroup.Wait() if fixup := forceGoDNS(); fixup != nil { testDots(t, "go") fixup() } if fixup := forceCgoDNS(); fixup != nil { testDots(t, "cgo") fixup() } } func testDots(t *testing.T, mode string) { names, err := LookupAddr("8.8.8.8") // Google dns server if err != nil { t.Errorf("LookupAddr(8.8.8.8): %v (mode=%v)", err, mode) } else { for _, name := range names { if !hasSuffixFold(name, ".google.com.") && !hasSuffixFold(name, ".google.") { t.Errorf("LookupAddr(8.8.8.8) = %v, want names ending in .google.com or .google with trailing dot (mode=%v)", names, mode) break } } } cname, err := LookupCNAME("www.mit.edu") if err != nil { t.Errorf("LookupCNAME(www.mit.edu, mode=%v): %v", mode, err) } else if !strings.HasSuffix(cname, ".") { t.Errorf("LookupCNAME(www.mit.edu) = %v, want cname ending in . with trailing dot (mode=%v)", cname, mode) } mxs, err := LookupMX("google.com") if err != nil { t.Errorf("LookupMX(google.com): %v (mode=%v)", err, mode) } else { for _, mx := range mxs { if !hasSuffixFold(mx.Host, ".google.com.") { t.Errorf("LookupMX(google.com) = %v, want names ending in .google.com. with trailing dot (mode=%v)", mxString(mxs), mode) break } } } nss, err := LookupNS("google.com") if err != nil { t.Errorf("LookupNS(google.com): %v (mode=%v)", err, mode) } else { for _, ns := range nss { if !hasSuffixFold(ns.Host, ".google.com.") { t.Errorf("LookupNS(google.com) = %v, want names ending in .google.com. with trailing dot (mode=%v)", nsString(nss), mode) break } } } cname, srvs, err := LookupSRV("ldap", "tcp", "google.com") if err != nil { t.Errorf("LookupSRV(ldap, tcp, google.com): %v (mode=%v)", err, mode) } else { if !hasSuffixFold(cname, ".google.com.") { t.Errorf("LookupSRV(ldap, tcp, google.com) returned cname=%v, want name ending in .google.com. with trailing dot (mode=%v)", cname, mode) } for _, srv := range srvs { if !hasSuffixFold(srv.Target, ".google.com.") { t.Errorf("LookupSRV(ldap, tcp, google.com) returned addrs=%v, want names ending in .google.com. with trailing dot (mode=%v)", srvString(srvs), mode) break } } } } func mxString(mxs []*MX) string { var buf strings.Builder sep := "" fmt.Fprintf(&buf, "[") for _, mx := range mxs { fmt.Fprintf(&buf, "%s%s:%d", sep, mx.Host, mx.Pref) sep = " " } fmt.Fprintf(&buf, "]") return buf.String() } func nsString(nss []*NS) string { var buf strings.Builder sep := "" fmt.Fprintf(&buf, "[") for _, ns := range nss { fmt.Fprintf(&buf, "%s%s", sep, ns.Host) sep = " " } fmt.Fprintf(&buf, "]") return buf.String() } func srvString(srvs []*SRV) string { var buf strings.Builder sep := "" fmt.Fprintf(&buf, "[") for _, srv := range srvs { fmt.Fprintf(&buf, "%s%s:%d:%d:%d", sep, srv.Target, srv.Port, srv.Priority, srv.Weight) sep = " " } fmt.Fprintf(&buf, "]") return buf.String() } func TestLookupPort(t *testing.T) { // See https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml // // Please be careful about adding new test cases. // There are platforms which have incomplete mappings for // restricted resource access and security reasons. type test struct { network string name string port int ok bool } var tests = []test{ {"tcp", "0", 0, true}, {"udp", "0", 0, true}, {"udp", "domain", 53, true}, {"--badnet--", "zzz", 0, false}, {"tcp", "--badport--", 0, false}, {"tcp", "-1", 0, false}, {"tcp", "65536", 0, false}, {"udp", "-1", 0, false}, {"udp", "65536", 0, false}, {"tcp", "123456789", 0, false}, // Issue 13610: LookupPort("tcp", "") {"tcp", "", 0, true}, {"tcp4", "", 0, true}, {"tcp6", "", 0, true}, {"udp", "", 0, true}, {"udp4", "", 0, true}, {"udp6", "", 0, true}, } switch runtime.GOOS { case "android": if netGoBuildTag { t.Skipf("not supported on %s without cgo; see golang.org/issues/14576", runtime.GOOS) } default: tests = append(tests, test{"tcp", "http", 80, true}) } for _, tt := range tests { port, err := LookupPort(tt.network, tt.name) if port != tt.port || (err == nil) != tt.ok { t.Errorf("LookupPort(%q, %q) = %d, %v; want %d, error=%t", tt.network, tt.name, port, err, tt.port, !tt.ok) } if err != nil { if perr := parseLookupPortError(err); perr != nil { t.Error(perr) } } } } // Like TestLookupPort but with minimal tests that should always pass // because the answers are baked-in to the net package. func TestLookupPort_Minimal(t *testing.T) { type test struct { network string name string port int } var tests = []test{ {"tcp", "http", 80}, {"tcp", "HTTP", 80}, // case shouldn't matter {"tcp", "https", 443}, {"tcp", "ssh", 22}, {"tcp", "gopher", 70}, {"tcp4", "http", 80}, {"tcp6", "http", 80}, } for _, tt := range tests { port, err := LookupPort(tt.network, tt.name) if port != tt.port || err != nil { t.Errorf("LookupPort(%q, %q) = %d, %v; want %d, error=nil", tt.network, tt.name, port, err, tt.port) } } } func TestLookupProtocol_Minimal(t *testing.T) { type test struct { name string want int } var tests = []test{ {"tcp", 6}, {"TcP", 6}, // case shouldn't matter {"icmp", 1}, {"igmp", 2}, {"udp", 17}, {"ipv6-icmp", 58}, } for _, tt := range tests { got, err := lookupProtocol(context.Background(), tt.name) if got != tt.want || err != nil { t.Errorf("LookupProtocol(%q) = %d, %v; want %d, error=nil", tt.name, got, err, tt.want) } } } func TestLookupNonLDH(t *testing.T) { defer dnsWaitGroup.Wait() if fixup := forceGoDNS(); fixup != nil { defer fixup() } // "LDH" stands for letters, digits, and hyphens and is the usual // description of standard DNS names. // This test is checking that other kinds of names are reported // as not found, not reported as invalid names. addrs, err := LookupHost("!!!.###.bogus..domain.") if err == nil { t.Fatalf("lookup succeeded: %v", addrs) } if !strings.HasSuffix(err.Error(), errNoSuchHost.Error()) { t.Fatalf("lookup error = %v, want %v", err, errNoSuchHost) } if !err.(*DNSError).IsNotFound { t.Fatalf("lookup error = %v, want true", err.(*DNSError).IsNotFound) } } func TestLookupContextCancel(t *testing.T) { mustHaveExternalNetwork(t) testenv.SkipFlakyNet(t) origTestHookLookupIP := testHookLookupIP defer func() { dnsWaitGroup.Wait() testHookLookupIP = origTestHookLookupIP }() lookupCtx, cancelLookup := context.WithCancel(context.Background()) unblockLookup := make(chan struct{}) // Set testHookLookupIP to start a new, concurrent call to LookupIPAddr // and cancel the original one, then block until the canceled call has returned // (ensuring that it has performed any synchronous cleanup). testHookLookupIP = func( ctx context.Context, fn func(context.Context, string, string) ([]IPAddr, error), network string, host string, ) ([]IPAddr, error) { select { case <-unblockLookup: default: // Start a concurrent LookupIPAddr for the same host while the caller is // still blocked, and sleep a little to give it time to be deduplicated // before we cancel (and unblock) the caller. // (If the timing doesn't quite work out, we'll end up testing sequential // calls instead of concurrent ones, but the test should still pass.) t.Logf("starting concurrent LookupIPAddr") dnsWaitGroup.Add(1) go func() { defer dnsWaitGroup.Done() _, err := DefaultResolver.LookupIPAddr(context.Background(), host) if err != nil { t.Error(err) } }() time.Sleep(1 * time.Millisecond) } cancelLookup() <-unblockLookup // If the concurrent lookup above is deduplicated to this one // (as we expect to happen most of the time), it is important // that the original call does not cancel the shared Context. // (See https://go.dev/issue/22724.) Explicitly check for // cancellation now, just in case fn itself doesn't notice it. if err := ctx.Err(); err != nil { t.Logf("testHookLookupIP canceled") return nil, err } t.Logf("testHookLookupIP performing lookup") return fn(ctx, network, host) } _, err := DefaultResolver.LookupIPAddr(lookupCtx, "google.com") if dnsErr, ok := err.(*DNSError); !ok || dnsErr.Err != errCanceled.Error() { t.Errorf("unexpected error from canceled, blocked LookupIPAddr: %v", err) } close(unblockLookup) } // Issue 24330: treat the nil *Resolver like a zero value. Verify nothing // crashes if nil is used. func TestNilResolverLookup(t *testing.T) { mustHaveExternalNetwork(t) var r *Resolver = nil ctx := context.Background() // Don't care about the results, just that nothing panics: r.LookupAddr(ctx, "8.8.8.8") r.LookupCNAME(ctx, "google.com") r.LookupHost(ctx, "google.com") r.LookupIPAddr(ctx, "google.com") r.LookupIP(ctx, "ip", "google.com") r.LookupMX(ctx, "gmail.com") r.LookupNS(ctx, "google.com") r.LookupPort(ctx, "tcp", "smtp") r.LookupSRV(ctx, "service", "proto", "name") r.LookupTXT(ctx, "gmail.com") } // TestLookupHostCancel verifies that lookup works even after many // canceled lookups (see golang.org/issue/24178 for details). func TestLookupHostCancel(t *testing.T) { mustHaveExternalNetwork(t) testenv.SkipFlakyNet(t) t.Parallel() // Executes 600ms worth of sequential sleeps. const ( google = "www.google.com" invalidDomain = "invalid.invalid" // RFC 2606 reserves .invalid n = 600 // this needs to be larger than threadLimit size ) _, err := LookupHost(google) if err != nil { t.Fatal(err) } ctx, cancel := context.WithCancel(context.Background()) cancel() for i := 0; i < n; i++ { addr, err := DefaultResolver.LookupHost(ctx, invalidDomain) if err == nil { t.Fatalf("LookupHost(%q): returns %v, but should fail", invalidDomain, addr) } // Don't verify what the actual error is. // We know that it must be non-nil because the domain is invalid, // but we don't have any guarantee that LookupHost actually bothers // to check for cancellation on the fast path. // (For example, it could use a local cache to avoid blocking entirely.) // The lookup may deduplicate in-flight requests, so give it time to settle // in between. time.Sleep(time.Millisecond * 1) } _, err = LookupHost(google) if err != nil { t.Fatal(err) } } type lookupCustomResolver struct { *Resolver mu sync.RWMutex dialed bool } func (lcr *lookupCustomResolver) dial() func(ctx context.Context, network, address string) (Conn, error) { return func(ctx context.Context, network, address string) (Conn, error) { lcr.mu.Lock() lcr.dialed = true lcr.mu.Unlock() return Dial(network, address) } } // TestConcurrentPreferGoResolversDial tests that multiple resolvers with the // PreferGo option used concurrently are all dialed properly. func TestConcurrentPreferGoResolversDial(t *testing.T) { switch runtime.GOOS { case "plan9": // TODO: plan9 implementation of the resolver uses the Dial function since // https://go.dev/cl/409234, this test could probably be reenabled. t.Skipf("skip on %v", runtime.GOOS) } testenv.MustHaveExternalNetwork(t) testenv.SkipFlakyNet(t) defer dnsWaitGroup.Wait() resolvers := make([]*lookupCustomResolver, 2) for i := range resolvers { cs := lookupCustomResolver{Resolver: &Resolver{PreferGo: true}} cs.Dial = cs.dial() resolvers[i] = &cs } var wg sync.WaitGroup wg.Add(len(resolvers)) for i, resolver := range resolvers { go func(r *Resolver, index int) { defer wg.Done() _, err := r.LookupIPAddr(context.Background(), "google.com") if err != nil { t.Errorf("lookup failed for resolver %d: %q", index, err) } }(resolver.Resolver, i) } wg.Wait() if t.Failed() { t.FailNow() } for i, resolver := range resolvers { if !resolver.dialed { t.Errorf("custom resolver %d not dialed during lookup", i) } } } var ipVersionTests = []struct { network string version byte }{ {"tcp", 0}, {"tcp4", '4'}, {"tcp6", '6'}, {"udp", 0}, {"udp4", '4'}, {"udp6", '6'}, {"ip", 0}, {"ip4", '4'}, {"ip6", '6'}, {"ip7", 0}, {"", 0}, } func TestIPVersion(t *testing.T) { for _, tt := range ipVersionTests { if version := ipVersion(tt.network); version != tt.version { t.Errorf("Family for: %s. Expected: %s, Got: %s", tt.network, string(tt.version), string(version)) } } } // Issue 28600: The context that is used to lookup ips should always // preserve the values from the context that was passed into LookupIPAddr. func TestLookupIPAddrPreservesContextValues(t *testing.T) { origTestHookLookupIP := testHookLookupIP defer func() { testHookLookupIP = origTestHookLookupIP }() keyValues := []struct { key, value any }{ {"key-1", 12}, {384, "value2"}, {new(float64), 137}, } ctx := context.Background() for _, kv := range keyValues { ctx = context.WithValue(ctx, kv.key, kv.value) } wantIPs := []IPAddr{ {IP: IPv4(127, 0, 0, 1)}, {IP: IPv6loopback}, } checkCtxValues := func(ctx_ context.Context, fn func(context.Context, string, string) ([]IPAddr, error), network, host string) ([]IPAddr, error) { for _, kv := range keyValues { g, w := ctx_.Value(kv.key), kv.value if !reflect.DeepEqual(g, w) { t.Errorf("Value lookup:\n\tGot: %v\n\tWant: %v", g, w) } } return wantIPs, nil } testHookLookupIP = checkCtxValues resolvers := []*Resolver{ nil, new(Resolver), } for i, resolver := range resolvers { gotIPs, err := resolver.LookupIPAddr(ctx, "golang.org") if err != nil { t.Errorf("Resolver #%d: unexpected error: %v", i, err) } if !reflect.DeepEqual(gotIPs, wantIPs) { t.Errorf("#%d: mismatched IPAddr results\n\tGot: %v\n\tWant: %v", i, gotIPs, wantIPs) } } } // Issue 30521: The lookup group should call the resolver for each network. func TestLookupIPAddrConcurrentCallsForNetworks(t *testing.T) { origTestHookLookupIP := testHookLookupIP defer func() { testHookLookupIP = origTestHookLookupIP }() queries := [][]string{ {"udp", "golang.org"}, {"udp4", "golang.org"}, {"udp6", "golang.org"}, {"udp", "golang.org"}, {"udp", "golang.org"}, } results := map[[2]string][]IPAddr{ {"udp", "golang.org"}: { {IP: IPv4(127, 0, 0, 1)}, {IP: IPv6loopback}, }, {"udp4", "golang.org"}: { {IP: IPv4(127, 0, 0, 1)}, }, {"udp6", "golang.org"}: { {IP: IPv6loopback}, }, } calls := int32(0) waitCh := make(chan struct{}) testHookLookupIP = func(ctx context.Context, fn func(context.Context, string, string) ([]IPAddr, error), network, host string) ([]IPAddr, error) { // We'll block until this is called one time for each different // expected result. This will ensure that the lookup group would wait // for the existing call if it was to be reused. if atomic.AddInt32(&calls, 1) == int32(len(results)) { close(waitCh) } select { case <-waitCh: case <-ctx.Done(): return nil, ctx.Err() } return results[[2]string{network, host}], nil } ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second) defer cancel() wg := sync.WaitGroup{} for _, q := range queries { network := q[0] host := q[1] wg.Add(1) go func() { defer wg.Done() gotIPs, err := DefaultResolver.lookupIPAddr(ctx, network, host) if err != nil { t.Errorf("lookupIPAddr(%v, %v): unexpected error: %v", network, host, err) } wantIPs := results[[2]string{network, host}] if !reflect.DeepEqual(gotIPs, wantIPs) { t.Errorf("lookupIPAddr(%v, %v): mismatched IPAddr results\n\tGot: %v\n\tWant: %v", network, host, gotIPs, wantIPs) } }() } wg.Wait() } // Issue 53995: Resolver.LookupIP should return error for empty host name. func TestResolverLookupIPWithEmptyHost(t *testing.T) { _, err := DefaultResolver.LookupIP(context.Background(), "ip", "") if err == nil { t.Fatal("DefaultResolver.LookupIP for empty host success, want no host error") } if !strings.HasSuffix(err.Error(), errNoSuchHost.Error()) { t.Fatalf("lookup error = %v, want %v", err, errNoSuchHost) } } func TestWithUnexpiredValuesPreserved(t *testing.T) { ctx, cancel := context.WithCancel(context.Background()) // Insert a value into it. key, value := "key-1", 2 ctx = context.WithValue(ctx, key, value) // Now use the "values preserving context" like // we would for LookupIPAddr. See Issue 28600. ctx = withUnexpiredValuesPreserved(ctx) // Lookup before expiry. if g, w := ctx.Value(key), value; g != w { t.Errorf("Lookup before expiry: Got %v Want %v", g, w) } // Cancel the context. cancel() // Lookup after expiry should return nil if g := ctx.Value(key); g != nil { t.Errorf("Lookup after expiry: Got %v want nil", g) } } // Issue 31597: don't panic on null byte in name func TestLookupNullByte(t *testing.T) { testenv.MustHaveExternalNetwork(t) testenv.SkipFlakyNet(t) LookupHost("foo\x00bar") // check that it doesn't panic; it used to on Windows } func TestResolverLookupIP(t *testing.T) { testenv.MustHaveExternalNetwork(t) v4Ok := supportsIPv4() && *testIPv4 v6Ok := supportsIPv6() && *testIPv6 defer dnsWaitGroup.Wait() for _, impl := range []struct { name string fn func() func() }{ {"go", forceGoDNS}, {"cgo", forceCgoDNS}, } { t.Run("implementation: "+impl.name, func(t *testing.T) { fixup := impl.fn() if fixup == nil { t.Skip("not supported") } defer fixup() for _, network := range []string{"ip", "ip4", "ip6"} { t.Run("network: "+network, func(t *testing.T) { switch { case network == "ip4" && !v4Ok: t.Skip("IPv4 is not supported") case network == "ip6" && !v6Ok: t.Skip("IPv6 is not supported") } // google.com has both A and AAAA records. const host = "google.com" ips, err := DefaultResolver.LookupIP(context.Background(), network, host) if err != nil { testenv.SkipFlakyNet(t) t.Fatalf("DefaultResolver.LookupIP(%q, %q): failed with unexpected error: %v", network, host, err) } var v4Addrs []netip.Addr var v6Addrs []netip.Addr for _, ip := range ips { if addr, ok := netip.AddrFromSlice(ip); ok { if addr.Is4() { v4Addrs = append(v4Addrs, addr) } else { v6Addrs = append(v6Addrs, addr) } } else { t.Fatalf("IP=%q is neither IPv4 nor IPv6", ip) } } // Check that we got the expected addresses. if network == "ip4" || network == "ip" && v4Ok { if len(v4Addrs) == 0 { t.Errorf("DefaultResolver.LookupIP(%q, %q): no IPv4 addresses", network, host) } } if network == "ip6" || network == "ip" && v6Ok { if len(v6Addrs) == 0 { t.Errorf("DefaultResolver.LookupIP(%q, %q): no IPv6 addresses", network, host) } } // Check that we didn't get any unexpected addresses. if network == "ip6" && len(v4Addrs) > 0 { t.Errorf("DefaultResolver.LookupIP(%q, %q): unexpected IPv4 addresses: %v", network, host, v4Addrs) } if network == "ip4" && len(v6Addrs) > 0 { t.Errorf("DefaultResolver.LookupIP(%q, %q): unexpected IPv6 or IPv4-mapped IPv6 addresses: %v", network, host, v6Addrs) } }) } }) } } // A context timeout should still return a DNSError. func TestDNSTimeout(t *testing.T) { origTestHookLookupIP := testHookLookupIP defer func() { testHookLookupIP = origTestHookLookupIP }() defer dnsWaitGroup.Wait() timeoutHookGo := make(chan bool, 1) timeoutHook := func(ctx context.Context, fn func(context.Context, string, string) ([]IPAddr, error), network, host string) ([]IPAddr, error) { <-timeoutHookGo return nil, context.DeadlineExceeded } testHookLookupIP = timeoutHook checkErr := func(err error) { t.Helper() if err == nil { t.Error("expected an error") } else if dnserr, ok := err.(*DNSError); !ok { t.Errorf("got error type %T, want %T", err, (*DNSError)(nil)) } else if !dnserr.IsTimeout { t.Errorf("got error %#v, want IsTimeout == true", dnserr) } else if isTimeout := dnserr.Timeout(); !isTimeout { t.Errorf("got err.Timeout() == %t, want true", isTimeout) } } // Single lookup. timeoutHookGo <- true _, err := LookupIP("golang.org") checkErr(err) // Double lookup. var err1, err2 error var wg sync.WaitGroup wg.Add(2) go func() { defer wg.Done() _, err1 = LookupIP("golang1.org") }() go func() { defer wg.Done() _, err2 = LookupIP("golang1.org") }() close(timeoutHookGo) wg.Wait() checkErr(err1) checkErr(err2) // Double lookup with context. timeoutHookGo = make(chan bool) ctx, cancel := context.WithTimeout(context.Background(), time.Nanosecond) wg.Add(2) go func() { defer wg.Done() _, err1 = DefaultResolver.LookupIPAddr(ctx, "golang2.org") }() go func() { defer wg.Done() _, err2 = DefaultResolver.LookupIPAddr(ctx, "golang2.org") }() time.Sleep(10 * time.Nanosecond) close(timeoutHookGo) wg.Wait() checkErr(err1) checkErr(err2) cancel() } func TestLookupNoData(t *testing.T) { if runtime.GOOS == "plan9" { t.Skip("not supported on plan9") } mustHaveExternalNetwork(t) testLookupNoData(t, "default resolver") func() { defer forceGoDNS()() testLookupNoData(t, "forced go resolver") }() func() { defer forceCgoDNS()() testLookupNoData(t, "forced cgo resolver") }() } func testLookupNoData(t *testing.T, prefix string) { attempts := 0 for { // Domain that doesn't have any A/AAAA RRs, but has different one (in this case a TXT), // so that it returns an empty response without any error codes (NXDOMAIN). _, err := LookupHost("golang.rsc.io.") if err == nil { t.Errorf("%v: unexpected success", prefix) return } var dnsErr *DNSError if errors.As(err, &dnsErr) { succeeded := true if !dnsErr.IsNotFound { succeeded = false t.Logf("%v: IsNotFound is set to false", prefix) } if dnsErr.Err != errNoSuchHost.Error() { succeeded = false t.Logf("%v: error message is not equal to: %v", prefix, errNoSuchHost.Error()) } if succeeded { return } } testenv.SkipFlakyNet(t) if attempts < len(backoffDuration) { dur := backoffDuration[attempts] t.Logf("%v: backoff %v after failure %v\n", prefix, dur, err) time.Sleep(dur) attempts++ continue } t.Errorf("%v: unexpected error: %v", prefix, err) return } } func TestLookupPortNotFound(t *testing.T) { allResolvers(t, func(t *testing.T) { _, err := LookupPort("udp", "_-unknown-service-") var dnsErr *DNSError if !errors.As(err, &dnsErr) || !dnsErr.IsNotFound { t.Fatalf("unexpected error: %v", err) } }) } // submissions service is only available through a tcp network, see: // https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=submissions var tcpOnlyService = func() string { // plan9 does not have submissions service defined in the service database. if runtime.GOOS == "plan9" { return "https" } return "submissions" }() func TestLookupPortDifferentNetwork(t *testing.T) { allResolvers(t, func(t *testing.T) { _, err := LookupPort("udp", tcpOnlyService) var dnsErr *DNSError if !errors.As(err, &dnsErr) || !dnsErr.IsNotFound { t.Fatalf("unexpected error: %v", err) } }) } func TestLookupPortEmptyNetworkString(t *testing.T) { allResolvers(t, func(t *testing.T) { _, err := LookupPort("", tcpOnlyService) if err != nil { t.Fatalf("unexpected error: %v", err) } }) } func TestLookupPortIPNetworkString(t *testing.T) { allResolvers(t, func(t *testing.T) { _, err := LookupPort("ip", tcpOnlyService) if err != nil { t.Fatalf("unexpected error: %v", err) } }) } func TestLookupNoSuchHost(t *testing.T) { mustHaveExternalNetwork(t) const testNXDOMAIN = "invalid.invalid." const testNODATA = "_ldap._tcp.google.com." tests := []struct { name string query func() error }{ { name: "LookupCNAME NXDOMAIN", query: func() error { _, err := LookupCNAME(testNXDOMAIN) return err }, }, { name: "LookupHost NXDOMAIN", query: func() error { _, err := LookupHost(testNXDOMAIN) return err }, }, { name: "LookupHost NODATA", query: func() error { _, err := LookupHost(testNODATA) return err }, }, { name: "LookupMX NXDOMAIN", query: func() error { _, err := LookupMX(testNXDOMAIN) return err }, }, { name: "LookupMX NODATA", query: func() error { _, err := LookupMX(testNODATA) return err }, }, { name: "LookupNS NXDOMAIN", query: func() error { _, err := LookupNS(testNXDOMAIN) return err }, }, { name: "LookupNS NODATA", query: func() error { _, err := LookupNS(testNODATA) return err }, }, { name: "LookupSRV NXDOMAIN", query: func() error { _, _, err := LookupSRV("unknown", "tcp", testNXDOMAIN) return err }, }, { name: "LookupTXT NXDOMAIN", query: func() error { _, err := LookupTXT(testNXDOMAIN) return err }, }, { name: "LookupTXT NODATA", query: func() error { _, err := LookupTXT(testNODATA) return err }, }, } for _, v := range tests { t.Run(v.name, func(t *testing.T) { allResolvers(t, func(t *testing.T) { attempts := 0 for { err := v.query() if err == nil { t.Errorf("unexpected success") return } if dnsErr, ok := err.(*DNSError); ok { succeeded := true if !dnsErr.IsNotFound { succeeded = false t.Log("IsNotFound is set to false") } if dnsErr.Err != errNoSuchHost.Error() { succeeded = false t.Logf("error message is not equal to: %v", errNoSuchHost.Error()) } if succeeded { return } } testenv.SkipFlakyNet(t) if attempts < len(backoffDuration) { dur := backoffDuration[attempts] t.Logf("backoff %v after failure %v\n", dur, err) time.Sleep(dur) attempts++ continue } t.Errorf("unexpected error: %v", err) return } }) }) } } func TestDNSErrorUnwrap(t *testing.T) { if runtime.GOOS == "plan9" { // The Plan 9 implementation of the resolver doesn't use the Dial function yet. See https://go.dev/cl/409234 t.Skip("skipping on plan9") } rDeadlineExcceeded := &Resolver{PreferGo: true, Dial: func(ctx context.Context, network, address string) (Conn, error) { return nil, context.DeadlineExceeded }} rCancelled := &Resolver{PreferGo: true, Dial: func(ctx context.Context, network, address string) (Conn, error) { return nil, context.Canceled }} _, err := rDeadlineExcceeded.LookupHost(context.Background(), "test.go.dev") if !errors.Is(err, context.DeadlineExceeded) { t.Errorf("errors.Is(err, context.DeadlineExceeded) = false; want = true") } _, err = rCancelled.LookupHost(context.Background(), "test.go.dev") if !errors.Is(err, context.Canceled) { t.Errorf("errors.Is(err, context.Canceled) = false; want = true") } ctx, cancel := context.WithCancel(context.Background()) cancel() _, err = goResolver.LookupHost(ctx, "text.go.dev") if !errors.Is(err, context.Canceled) { t.Errorf("errors.Is(err, context.Canceled) = false; want = true") } }