package dns_test import ( "testing" "time" "github.com/google/go-cmp/cmp" "github.com/miekg/dns" "github.com/xtls/xray-core/v1/app/dispatcher" . "github.com/xtls/xray-core/v1/app/dns" "github.com/xtls/xray-core/v1/app/policy" "github.com/xtls/xray-core/v1/app/proxyman" _ "github.com/xtls/xray-core/v1/app/proxyman/outbound" "github.com/xtls/xray-core/v1/app/router" "github.com/xtls/xray-core/v1/common" "github.com/xtls/xray-core/v1/common/net" "github.com/xtls/xray-core/v1/common/serial" "github.com/xtls/xray-core/v1/core" feature_dns "github.com/xtls/xray-core/v1/features/dns" "github.com/xtls/xray-core/v1/proxy/freedom" "github.com/xtls/xray-core/v1/testing/servers/udp" ) type staticHandler struct { } func (*staticHandler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) { ans := new(dns.Msg) ans.Id = r.Id var clientIP net.IP opt := r.IsEdns0() if opt != nil { for _, o := range opt.Option { if o.Option() == dns.EDNS0SUBNET { subnet := o.(*dns.EDNS0_SUBNET) clientIP = subnet.Address } } } for _, q := range r.Question { switch { case q.Name == "google.com." && q.Qtype == dns.TypeA: if clientIP == nil { rr, _ := dns.NewRR("google.com. IN A 8.8.8.8") ans.Answer = append(ans.Answer, rr) } else { rr, _ := dns.NewRR("google.com. IN A 8.8.4.4") ans.Answer = append(ans.Answer, rr) } case q.Name == "api.google.com." && q.Qtype == dns.TypeA: rr, _ := dns.NewRR("api.google.com. IN A 8.8.7.7") ans.Answer = append(ans.Answer, rr) case q.Name == "v2.api.google.com." && q.Qtype == dns.TypeA: rr, _ := dns.NewRR("v2.api.google.com. IN A 8.8.7.8") ans.Answer = append(ans.Answer, rr) case q.Name == "facebook.com." && q.Qtype == dns.TypeA: rr, _ := dns.NewRR("facebook.com. IN A 9.9.9.9") ans.Answer = append(ans.Answer, rr) case q.Name == "ipv6.google.com." && q.Qtype == dns.TypeA: rr, err := dns.NewRR("ipv6.google.com. IN A 8.8.8.7") common.Must(err) ans.Answer = append(ans.Answer, rr) case q.Name == "ipv6.google.com." && q.Qtype == dns.TypeAAAA: rr, err := dns.NewRR("ipv6.google.com. IN AAAA 2001:4860:4860::8888") common.Must(err) ans.Answer = append(ans.Answer, rr) case q.Name == "notexist.google.com." && q.Qtype == dns.TypeAAAA: ans.MsgHdr.Rcode = dns.RcodeNameError case q.Name == "hostname." && q.Qtype == dns.TypeA: rr, _ := dns.NewRR("hostname. IN A 127.0.0.1") ans.Answer = append(ans.Answer, rr) case q.Name == "hostname.local." && q.Qtype == dns.TypeA: rr, _ := dns.NewRR("hostname.local. IN A 127.0.0.1") ans.Answer = append(ans.Answer, rr) case q.Name == "hostname.localdomain." && q.Qtype == dns.TypeA: rr, _ := dns.NewRR("hostname.localdomain. IN A 127.0.0.1") ans.Answer = append(ans.Answer, rr) case q.Name == "localhost." && q.Qtype == dns.TypeA: rr, _ := dns.NewRR("localhost. IN A 127.0.0.2") ans.Answer = append(ans.Answer, rr) case q.Name == "localhost-a." && q.Qtype == dns.TypeA: rr, _ := dns.NewRR("localhost-a. IN A 127.0.0.3") ans.Answer = append(ans.Answer, rr) case q.Name == "localhost-b." && q.Qtype == dns.TypeA: rr, _ := dns.NewRR("localhost-b. IN A 127.0.0.4") ans.Answer = append(ans.Answer, rr) case q.Name == "Mijia\\ Cloud." && q.Qtype == dns.TypeA: rr, _ := dns.NewRR("Mijia\\ Cloud. IN A 127.0.0.1") ans.Answer = append(ans.Answer, rr) } } w.WriteMsg(ans) } func TestUDPServerSubnet(t *testing.T) { port := udp.PickPort() dnsServer := dns.Server{ Addr: "127.0.0.1:" + port.String(), Net: "udp", Handler: &staticHandler{}, UDPSize: 1200, } go dnsServer.ListenAndServe() time.Sleep(time.Second) config := &core.Config{ App: []*serial.TypedMessage{ serial.ToTypedMessage(&Config{ NameServers: []*net.Endpoint{ { Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, }, ClientIp: []byte{7, 8, 9, 10}, }), serial.ToTypedMessage(&dispatcher.Config{}), serial.ToTypedMessage(&proxyman.OutboundConfig{}), serial.ToTypedMessage(&policy.Config{}), }, Outbound: []*core.OutboundHandlerConfig{ { ProxySettings: serial.ToTypedMessage(&freedom.Config{}), }, }, } v, err := core.New(config) common.Must(err) client := v.GetFeature(feature_dns.ClientType()).(feature_dns.Client) ips, err := client.LookupIP("google.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{8, 8, 4, 4}}); r != "" { t.Fatal(r) } } func TestUDPServer(t *testing.T) { port := udp.PickPort() dnsServer := dns.Server{ Addr: "127.0.0.1:" + port.String(), Net: "udp", Handler: &staticHandler{}, UDPSize: 1200, } go dnsServer.ListenAndServe() time.Sleep(time.Second) config := &core.Config{ App: []*serial.TypedMessage{ serial.ToTypedMessage(&Config{ NameServers: []*net.Endpoint{ { Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, }, }), serial.ToTypedMessage(&dispatcher.Config{}), serial.ToTypedMessage(&proxyman.OutboundConfig{}), serial.ToTypedMessage(&policy.Config{}), }, Outbound: []*core.OutboundHandlerConfig{ { ProxySettings: serial.ToTypedMessage(&freedom.Config{}), }, }, } v, err := core.New(config) common.Must(err) client := v.GetFeature(feature_dns.ClientType()).(feature_dns.Client) { ips, err := client.LookupIP("google.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{8, 8, 8, 8}}); r != "" { t.Fatal(r) } } { ips, err := client.LookupIP("facebook.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{9, 9, 9, 9}}); r != "" { t.Fatal(r) } } { _, err := client.LookupIP("notexist.google.com") if err == nil { t.Fatal("nil error") } if r := feature_dns.RCodeFromError(err); r != uint16(dns.RcodeNameError) { t.Fatal("expected NameError, but got ", r) } } { clientv6 := client.(feature_dns.IPv6Lookup) ips, err := clientv6.LookupIPv6("ipv4only.google.com") if err != feature_dns.ErrEmptyResponse { t.Fatal("error: ", err) } if len(ips) != 0 { t.Fatal("ips: ", ips) } } dnsServer.Shutdown() { ips, err := client.LookupIP("google.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{8, 8, 8, 8}}); r != "" { t.Fatal(r) } } } func TestPrioritizedDomain(t *testing.T) { port := udp.PickPort() dnsServer := dns.Server{ Addr: "127.0.0.1:" + port.String(), Net: "udp", Handler: &staticHandler{}, UDPSize: 1200, } go dnsServer.ListenAndServe() time.Sleep(time.Second) config := &core.Config{ App: []*serial.TypedMessage{ serial.ToTypedMessage(&Config{ NameServers: []*net.Endpoint{ { Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: 9999, /* unreachable */ }, }, NameServer: []*NameServer{ { Address: &net.Endpoint{ Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, PrioritizedDomain: []*NameServer_PriorityDomain{ { Type: DomainMatchingType_Full, Domain: "google.com", }, }, }, }, }), serial.ToTypedMessage(&dispatcher.Config{}), serial.ToTypedMessage(&proxyman.OutboundConfig{}), serial.ToTypedMessage(&policy.Config{}), }, Outbound: []*core.OutboundHandlerConfig{ { ProxySettings: serial.ToTypedMessage(&freedom.Config{}), }, }, } v, err := core.New(config) common.Must(err) client := v.GetFeature(feature_dns.ClientType()).(feature_dns.Client) startTime := time.Now() { ips, err := client.LookupIP("google.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{8, 8, 8, 8}}); r != "" { t.Fatal(r) } } endTime := time.Now() if startTime.After(endTime.Add(time.Second * 2)) { t.Error("DNS query doesn't finish in 2 seconds.") } } func TestUDPServerIPv6(t *testing.T) { port := udp.PickPort() dnsServer := dns.Server{ Addr: "127.0.0.1:" + port.String(), Net: "udp", Handler: &staticHandler{}, UDPSize: 1200, } go dnsServer.ListenAndServe() time.Sleep(time.Second) config := &core.Config{ App: []*serial.TypedMessage{ serial.ToTypedMessage(&Config{ NameServers: []*net.Endpoint{ { Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, }, }), serial.ToTypedMessage(&dispatcher.Config{}), serial.ToTypedMessage(&proxyman.OutboundConfig{}), serial.ToTypedMessage(&policy.Config{}), }, Outbound: []*core.OutboundHandlerConfig{ { ProxySettings: serial.ToTypedMessage(&freedom.Config{}), }, }, } v, err := core.New(config) common.Must(err) client := v.GetFeature(feature_dns.ClientType()).(feature_dns.Client) client6 := client.(feature_dns.IPv6Lookup) { ips, err := client6.LookupIPv6("ipv6.google.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{32, 1, 72, 96, 72, 96, 0, 0, 0, 0, 0, 0, 0, 0, 136, 136}}); r != "" { t.Fatal(r) } } } func TestStaticHostDomain(t *testing.T) { port := udp.PickPort() dnsServer := dns.Server{ Addr: "127.0.0.1:" + port.String(), Net: "udp", Handler: &staticHandler{}, UDPSize: 1200, } go dnsServer.ListenAndServe() time.Sleep(time.Second) config := &core.Config{ App: []*serial.TypedMessage{ serial.ToTypedMessage(&Config{ NameServers: []*net.Endpoint{ { Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, }, StaticHosts: []*Config_HostMapping{ { Type: DomainMatchingType_Full, Domain: "example.com", ProxiedDomain: "google.com", }, }, }), serial.ToTypedMessage(&dispatcher.Config{}), serial.ToTypedMessage(&proxyman.OutboundConfig{}), serial.ToTypedMessage(&policy.Config{}), }, Outbound: []*core.OutboundHandlerConfig{ { ProxySettings: serial.ToTypedMessage(&freedom.Config{}), }, }, } v, err := core.New(config) common.Must(err) client := v.GetFeature(feature_dns.ClientType()).(feature_dns.Client) { ips, err := client.LookupIP("example.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{8, 8, 8, 8}}); r != "" { t.Fatal(r) } } dnsServer.Shutdown() } func TestIPMatch(t *testing.T) { port := udp.PickPort() dnsServer := dns.Server{ Addr: "127.0.0.1:" + port.String(), Net: "udp", Handler: &staticHandler{}, UDPSize: 1200, } go dnsServer.ListenAndServe() time.Sleep(time.Second) config := &core.Config{ App: []*serial.TypedMessage{ serial.ToTypedMessage(&Config{ NameServer: []*NameServer{ // private dns, not match { Address: &net.Endpoint{ Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, Geoip: []*router.GeoIP{ { CountryCode: "local", Cidr: []*router.CIDR{ { // inner ip, will not match Ip: []byte{192, 168, 11, 1}, Prefix: 32, }, }, }, }, }, // second dns, match ip { Address: &net.Endpoint{ Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, Geoip: []*router.GeoIP{ { CountryCode: "test", Cidr: []*router.CIDR{ { Ip: []byte{8, 8, 8, 8}, Prefix: 32, }, }, }, { CountryCode: "test", Cidr: []*router.CIDR{ { Ip: []byte{8, 8, 8, 4}, Prefix: 32, }, }, }, }, }, }, }), serial.ToTypedMessage(&dispatcher.Config{}), serial.ToTypedMessage(&proxyman.OutboundConfig{}), serial.ToTypedMessage(&policy.Config{}), }, Outbound: []*core.OutboundHandlerConfig{ { ProxySettings: serial.ToTypedMessage(&freedom.Config{}), }, }, } v, err := core.New(config) common.Must(err) client := v.GetFeature(feature_dns.ClientType()).(feature_dns.Client) startTime := time.Now() { ips, err := client.LookupIP("google.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{8, 8, 8, 8}}); r != "" { t.Fatal(r) } } endTime := time.Now() if startTime.After(endTime.Add(time.Second * 2)) { t.Error("DNS query doesn't finish in 2 seconds.") } } func TestLocalDomain(t *testing.T) { port := udp.PickPort() dnsServer := dns.Server{ Addr: "127.0.0.1:" + port.String(), Net: "udp", Handler: &staticHandler{}, UDPSize: 1200, } go dnsServer.ListenAndServe() time.Sleep(time.Second) config := &core.Config{ App: []*serial.TypedMessage{ serial.ToTypedMessage(&Config{ NameServers: []*net.Endpoint{ { Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: 9999, /* unreachable */ }, }, NameServer: []*NameServer{ { Address: &net.Endpoint{ Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, PrioritizedDomain: []*NameServer_PriorityDomain{ // Equivalent of dotless:localhost {Type: DomainMatchingType_Regex, Domain: "^[^.]*localhost[^.]*$"}, }, Geoip: []*router.GeoIP{ { // Will match localhost, localhost-a and localhost-b, CountryCode: "local", Cidr: []*router.CIDR{ {Ip: []byte{127, 0, 0, 2}, Prefix: 32}, {Ip: []byte{127, 0, 0, 3}, Prefix: 32}, {Ip: []byte{127, 0, 0, 4}, Prefix: 32}, }, }, }, }, { Address: &net.Endpoint{ Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, PrioritizedDomain: []*NameServer_PriorityDomain{ // Equivalent of dotless: and domain:local {Type: DomainMatchingType_Regex, Domain: "^[^.]*$"}, {Type: DomainMatchingType_Subdomain, Domain: "local"}, {Type: DomainMatchingType_Subdomain, Domain: "localdomain"}, }, }, }, StaticHosts: []*Config_HostMapping{ { Type: DomainMatchingType_Full, Domain: "hostnamestatic", Ip: [][]byte{{127, 0, 0, 53}}, }, { Type: DomainMatchingType_Full, Domain: "hostnamealias", ProxiedDomain: "hostname.localdomain", }, }, }), serial.ToTypedMessage(&dispatcher.Config{}), serial.ToTypedMessage(&proxyman.OutboundConfig{}), serial.ToTypedMessage(&policy.Config{}), }, Outbound: []*core.OutboundHandlerConfig{ { ProxySettings: serial.ToTypedMessage(&freedom.Config{}), }, }, } v, err := core.New(config) common.Must(err) client := v.GetFeature(feature_dns.ClientType()).(feature_dns.Client) startTime := time.Now() { // Will match dotless: ips, err := client.LookupIP("hostname") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{127, 0, 0, 1}}); r != "" { t.Fatal(r) } } { // Will match domain:local ips, err := client.LookupIP("hostname.local") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{127, 0, 0, 1}}); r != "" { t.Fatal(r) } } { // Will match static ip ips, err := client.LookupIP("hostnamestatic") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{127, 0, 0, 53}}); r != "" { t.Fatal(r) } } { // Will match domain replacing ips, err := client.LookupIP("hostnamealias") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{127, 0, 0, 1}}); r != "" { t.Fatal(r) } } { // Will match dotless:localhost, but not expectIPs: 127.0.0.2, 127.0.0.3, then matches at dotless: ips, err := client.LookupIP("localhost") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{127, 0, 0, 2}}); r != "" { t.Fatal(r) } } { // Will match dotless:localhost, and expectIPs: 127.0.0.2, 127.0.0.3 ips, err := client.LookupIP("localhost-a") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{127, 0, 0, 3}}); r != "" { t.Fatal(r) } } { // Will match dotless:localhost, and expectIPs: 127.0.0.2, 127.0.0.3 ips, err := client.LookupIP("localhost-b") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{127, 0, 0, 4}}); r != "" { t.Fatal(r) } } { // Will match dotless: ips, err := client.LookupIP("Mijia Cloud") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{127, 0, 0, 1}}); r != "" { t.Fatal(r) } } endTime := time.Now() if startTime.After(endTime.Add(time.Second * 2)) { t.Error("DNS query doesn't finish in 2 seconds.") } } func TestMultiMatchPrioritizedDomain(t *testing.T) { port := udp.PickPort() dnsServer := dns.Server{ Addr: "127.0.0.1:" + port.String(), Net: "udp", Handler: &staticHandler{}, UDPSize: 1200, } go dnsServer.ListenAndServe() time.Sleep(time.Second) config := &core.Config{ App: []*serial.TypedMessage{ serial.ToTypedMessage(&Config{ NameServers: []*net.Endpoint{ { Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: 9999, /* unreachable */ }, }, NameServer: []*NameServer{ { Address: &net.Endpoint{ Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, PrioritizedDomain: []*NameServer_PriorityDomain{ { Type: DomainMatchingType_Subdomain, Domain: "google.com", }, }, Geoip: []*router.GeoIP{ { // Will only match 8.8.8.8 and 8.8.4.4 Cidr: []*router.CIDR{ {Ip: []byte{8, 8, 8, 8}, Prefix: 32}, {Ip: []byte{8, 8, 4, 4}, Prefix: 32}, }, }, }, }, { Address: &net.Endpoint{ Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, PrioritizedDomain: []*NameServer_PriorityDomain{ { Type: DomainMatchingType_Subdomain, Domain: "google.com", }, }, Geoip: []*router.GeoIP{ { // Will match 8.8.8.8 and 8.8.8.7, etc Cidr: []*router.CIDR{ {Ip: []byte{8, 8, 8, 7}, Prefix: 24}, }, }, }, }, { Address: &net.Endpoint{ Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, PrioritizedDomain: []*NameServer_PriorityDomain{ { Type: DomainMatchingType_Subdomain, Domain: "api.google.com", }, }, Geoip: []*router.GeoIP{ { // Will only match 8.8.7.7 (api.google.com) Cidr: []*router.CIDR{ {Ip: []byte{8, 8, 7, 7}, Prefix: 32}, }, }, }, }, { Address: &net.Endpoint{ Network: net.Network_UDP, Address: &net.IPOrDomain{ Address: &net.IPOrDomain_Ip{ Ip: []byte{127, 0, 0, 1}, }, }, Port: uint32(port), }, PrioritizedDomain: []*NameServer_PriorityDomain{ { Type: DomainMatchingType_Full, Domain: "v2.api.google.com", }, }, Geoip: []*router.GeoIP{ { // Will only match 8.8.7.8 (v2.api.google.com) Cidr: []*router.CIDR{ {Ip: []byte{8, 8, 7, 8}, Prefix: 32}, }, }, }, }, }, }), serial.ToTypedMessage(&dispatcher.Config{}), serial.ToTypedMessage(&proxyman.OutboundConfig{}), serial.ToTypedMessage(&policy.Config{}), }, Outbound: []*core.OutboundHandlerConfig{ { ProxySettings: serial.ToTypedMessage(&freedom.Config{}), }, }, } v, err := core.New(config) common.Must(err) client := v.GetFeature(feature_dns.ClientType()).(feature_dns.Client) startTime := time.Now() { // Will match server 1,2 and server 1 returns expected ip ips, err := client.LookupIP("google.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{8, 8, 8, 8}}); r != "" { t.Fatal(r) } } { // Will match server 1,2 and server 1 returns unexpected ip, then server 2 returns expected one clientv4 := client.(feature_dns.IPv4Lookup) ips, err := clientv4.LookupIPv4("ipv6.google.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{8, 8, 8, 7}}); r != "" { t.Fatal(r) } } { // Will match server 3,1,2 and server 3 returns expected one ips, err := client.LookupIP("api.google.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{8, 8, 7, 7}}); r != "" { t.Fatal(r) } } { // Will match server 4,3,1,2 and server 4 returns expected one ips, err := client.LookupIP("v2.api.google.com") if err != nil { t.Fatal("unexpected error: ", err) } if r := cmp.Diff(ips, []net.IP{{8, 8, 7, 8}}); r != "" { t.Fatal(r) } } endTime := time.Now() if startTime.After(endTime.Add(time.Second * 2)) { t.Error("DNS query doesn't finish in 2 seconds.") } }