// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1

package agent

import (
	"context"
	"fmt"
	"net"
	"sort"
	"strings"
	"testing"

	"github.com/miekg/dns"
	"github.com/stretchr/testify/require"

	"github.com/hashicorp/consul/agent/structs"
	"github.com/hashicorp/consul/api"
	"github.com/hashicorp/consul/lib"
	"github.com/hashicorp/consul/sdk/testutil/retry"
	"github.com/hashicorp/consul/testrpc"
)

func TestDNS_ServiceReverseLookup(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
						Address: "127.0.0.2",
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			m := new(dns.Msg)
			m.SetQuestion("2.0.0.127.in-addr.arpa.", dns.TypeANY)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			if err != nil {
				t.Fatalf("err: %v", err)
			}

			if len(in.Answer) != 1 {
				t.Fatalf("Bad: %#v", in)
			}

			ptrRec, ok := in.Answer[0].(*dns.PTR)
			if !ok {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if ptrRec.Ptr != serviceCanonicalDNSName("db", "service", "dc1", "consul", nil)+"." {
				t.Fatalf("Bad: %#v", ptrRec)
			}
		})
	}
}

func TestDNS_ServiceReverseLookup_IPV6(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "2001:db8::1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
						Address: "2001:db8::ff00:42:8329",
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			m := new(dns.Msg)
			m.SetQuestion("9.2.3.8.2.4.0.0.0.0.f.f.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.", dns.TypeANY)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			if err != nil {
				t.Fatalf("err: %v", err)
			}

			if len(in.Answer) != 1 {
				t.Fatalf("Bad: %#v", in)
			}

			ptrRec, ok := in.Answer[0].(*dns.PTR)
			if !ok {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if ptrRec.Ptr != serviceCanonicalDNSName("db", "service", "dc1", "consul", nil)+"." {
				t.Fatalf("Bad: %#v", ptrRec)
			}
		})
	}
}

func TestDNS_ServiceReverseLookup_CustomDomain(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		domain = "custom"
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
						Address: "127.0.0.2",
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			m := new(dns.Msg)
			m.SetQuestion("2.0.0.127.in-addr.arpa.", dns.TypeANY)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			if err != nil {
				t.Fatalf("err: %v", err)
			}

			if len(in.Answer) != 1 {
				t.Fatalf("Bad: %#v", in)
			}

			ptrRec, ok := in.Answer[0].(*dns.PTR)
			if !ok {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if ptrRec.Ptr != serviceCanonicalDNSName("db", "service", "dc1", "custom", nil)+"." {
				t.Fatalf("Bad: %#v", ptrRec)
			}
		})
	}
}

func TestDNS_ServiceReverseLookupNodeAddress(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
						Address: "127.0.0.1",
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			m := new(dns.Msg)
			m.SetQuestion("1.0.0.127.in-addr.arpa.", dns.TypeANY)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			if err != nil {
				t.Fatalf("err: %v", err)
			}

			if len(in.Answer) != 1 {
				t.Fatalf("Bad: %#v", in)
			}

			ptrRec, ok := in.Answer[0].(*dns.PTR)
			if !ok {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if ptrRec.Ptr != "foo.node.dc1.consul." {
				t.Fatalf("Bad: %#v", ptrRec)
			}
		})
	}
}

func TestDNS_ServiceLookupNoMultiCNAME(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "198.18.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Port:    12345,
						Address: "foo.node.consul",
					},
				}

				var out struct{}
				require.NoError(t, a.RPC(context.Background(), "Catalog.Register", args, &out))
			}

			// Register a second node node with the same service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "bar",
					Address:    "198.18.0.2",
					Service: &structs.NodeService{
						Service: "db",
						Port:    12345,
						Address: "bar.node.consul",
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			m := new(dns.Msg)
			m.SetQuestion("db.service.consul.", dns.TypeANY)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			require.NoError(t, err)

			// expect a CNAME and an A RR
			require.Len(t, in.Answer, 2)
			require.IsType(t, &dns.CNAME{}, in.Answer[0])
			require.IsType(t, &dns.A{}, in.Answer[1])
		})
	}
}

func TestDNS_ServiceLookupPreferNoCNAME(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "198.18.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Port:    12345,
						Address: "198.18.0.1",
					},
				}

				var out struct{}
				require.NoError(t, a.RPC(context.Background(), "Catalog.Register", args, &out))
			}

			// Register a second node node with the same service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "bar",
					Address:    "198.18.0.2",
					Service: &structs.NodeService{
						Service: "db",
						Port:    12345,
						Address: "bar.node.consul",
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			m := new(dns.Msg)
			m.SetQuestion("db.service.consul.", dns.TypeANY)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			require.NoError(t, err)

			// expect an A RR
			require.Len(t, in.Answer, 1)
			aRec, ok := in.Answer[0].(*dns.A)
			require.Truef(t, ok, "Not an A RR")

			require.Equal(t, "db.service.consul.", aRec.Hdr.Name)
			require.Equal(t, "198.18.0.1", aRec.A.String())
		})
	}
}

func TestDNS_ServiceLookupMultiAddrNoCNAME(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "198.18.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Port:    12345,
						Address: "198.18.0.1",
					},
				}

				var out struct{}
				require.NoError(t, a.RPC(context.Background(), "Catalog.Register", args, &out))
			}

			// Register a second node node with the same service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "bar",
					Address:    "198.18.0.2",
					Service: &structs.NodeService{
						Service: "db",
						Port:    12345,
						Address: "bar.node.consul",
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register a second node node with the same service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "baz",
					Address:    "198.18.0.3",
					Service: &structs.NodeService{
						Service: "db",
						Port:    12345,
						Address: "198.18.0.3",
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			m := new(dns.Msg)
			m.SetQuestion("db.service.consul.", dns.TypeANY)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			require.NoError(t, err)

			// expect two A RRs
			require.Len(t, in.Answer, 2)
			require.IsType(t, &dns.A{}, in.Answer[0])
			require.Equal(t, "db.service.consul.", in.Answer[0].Header().Name)
			isOneOfTheseIPs := func(ip net.IP) bool {
				if ip.Equal(net.ParseIP("198.18.0.1")) || ip.Equal(net.ParseIP("198.18.0.3")) {
					return true
				}
				return false
			}
			require.True(t, isOneOfTheseIPs(in.Answer[0].(*dns.A).A))
			require.IsType(t, &dns.A{}, in.Answer[1])
			require.Equal(t, "db.service.consul.", in.Answer[1].Header().Name)
			require.True(t, isOneOfTheseIPs(in.Answer[1].(*dns.A).A))
		})
	}
}

func TestDNS_ServiceLookup(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "db",
						},
						DNS: structs.QueryDNSOptions{
							TTL: "3s",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []string{
				"db.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				srvRec, ok := in.Answer[0].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if srvRec.Port != 12345 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Target != "foo.node.dc1.consul." {
					t.Fatalf("Bad: %#v", srvRec)
				}

				aRec, ok := in.Extra[0].(*dns.A)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Name != "foo.node.dc1.consul." {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.A.String() != "127.0.0.1" {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}

				if strings.Contains(question, "query") {
					// The query should have the TTL associated with the query registration.
					if srvRec.Hdr.Ttl != 3 {
						t.Fatalf("Bad: %#v", in.Answer[0])
					}
					if aRec.Hdr.Ttl != 3 {
						t.Fatalf("Bad: %#v", in.Extra[0])
					}
				} else {
					if srvRec.Hdr.Ttl != 0 {
						t.Fatalf("Bad: %#v", in.Answer[0])
					}
					if aRec.Hdr.Ttl != 0 {
						t.Fatalf("Bad: %#v", in.Extra[0])
					}
				}

			}

			// Lookup a non-existing service/query, we should receive an SOA.
			questions = []string{
				"nodb.service.consul.",
				"nope.query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Ns) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				soaRec, ok := in.Ns[0].(*dns.SOA)
				if !ok {
					t.Fatalf("Bad: %#v", in.Ns[0])
				}
				if soaRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Ns[0])
				}
			}
		})
	}
}

func TestDNS_ServiceLookupWithInternalServiceAddress(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		node_name = "my.test-node"
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			// The service is using the consul DNS name as service address
			// which triggers a lookup loop and a subsequent stack overflow
			// crash.
			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "foo",
				Address:    "127.0.0.1",
				Service: &structs.NodeService{
					Service: "db",
					Address: "db.service.consul",
					Port:    12345,
				},
			}

			var out struct{}
			if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
				t.Fatalf("err: %v", err)
			}

			// Looking up the service should not trigger a loop
			m := new(dns.Msg)
			m.SetQuestion("db.service.consul.", dns.TypeSRV)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			if err != nil {
				t.Fatalf("err: %v", err)
			}

			wantAnswer := []dns.RR{
				&dns.SRV{
					Hdr:      dns.RR_Header{Name: "db.service.consul.", Rrtype: 0x21, Class: 0x1, Rdlength: 0x1b},
					Priority: 0x1,
					Weight:   0x1,
					Port:     12345,
					Target:   "foo.node.dc1.consul.",
				},
			}
			require.Equal(t, wantAnswer, in.Answer, "answer")
			wantExtra := []dns.RR{
				&dns.A{
					Hdr: dns.RR_Header{Name: "foo.node.dc1.consul.", Rrtype: 0x1, Class: 0x1, Rdlength: 0x4},
					A:   []byte{0x7f, 0x0, 0x0, 0x1}, // 127.0.0.1
				},
			}
			require.Equal(t, wantExtra, in.Extra, "extra")
		})
	}
}

func TestDNS_ConnectServiceLookup(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register
			{
				args := structs.TestRegisterRequestProxy(t)
				args.Address = "127.0.0.55"
				args.Service.Proxy.DestinationServiceName = "db"
				args.Service.Address = ""
				args.Service.Port = 12345
				var out struct{}
				require.Nil(t, a.RPC(context.Background(), "Catalog.Register", args, &out))
			}

			// Look up the service
			questions := []string{
				"db.connect.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				require.Nil(t, err)
				require.Len(t, in.Answer, 1)

				srvRec, ok := in.Answer[0].(*dns.SRV)
				require.True(t, ok)
				require.Equal(t, uint16(12345), srvRec.Port)
				require.Equal(t, "foo.node.dc1.consul.", srvRec.Target)
				require.Equal(t, uint32(0), srvRec.Hdr.Ttl)

				cnameRec, ok := in.Extra[0].(*dns.A)
				require.True(t, ok)
				require.Equal(t, "foo.node.dc1.consul.", cnameRec.Hdr.Name)
				require.Equal(t, uint32(0), srvRec.Hdr.Ttl)
				require.Equal(t, "127.0.0.55", cnameRec.A.String())
			}
		})
	}
}

func TestDNS_IngressServiceLookup(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register ingress-gateway service
			{
				args := structs.TestRegisterIngressGateway(t)
				var out struct{}
				require.Nil(t, a.RPC(context.Background(), "Catalog.Register", args, &out))
			}

			// Register db service
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Address: "",
						Port:    80,
					},
				}

				var out struct{}
				require.Nil(t, a.RPC(context.Background(), "Catalog.Register", args, &out))
			}

			// Register proxy-defaults with 'http' protocol
			{
				req := structs.ConfigEntryRequest{
					Op:         structs.ConfigEntryUpsert,
					Datacenter: "dc1",
					Entry: &structs.ProxyConfigEntry{
						Kind: structs.ProxyDefaults,
						Name: structs.ProxyConfigGlobal,
						Config: map[string]interface{}{
							"protocol": "http",
						},
					},
					WriteRequest: structs.WriteRequest{Token: "root"},
				}
				var out bool
				require.Nil(t, a.RPC(context.Background(), "ConfigEntry.Apply", req, &out))
				require.True(t, out)
			}

			// Register ingress-gateway config entry
			{
				args := &structs.IngressGatewayConfigEntry{
					Name: "ingress-gateway",
					Kind: structs.IngressGateway,
					Listeners: []structs.IngressListener{
						{
							Port:     8888,
							Protocol: "http",
							Services: []structs.IngressService{
								{Name: "db"},
								{Name: "api"},
							},
						},
					},
				}

				req := structs.ConfigEntryRequest{
					Op:         structs.ConfigEntryUpsert,
					Datacenter: "dc1",
					Entry:      args,
				}
				var out bool
				require.Nil(t, a.RPC(context.Background(), "ConfigEntry.Apply", req, &out))
				require.True(t, out)
			}

			// Look up the service
			questions := []string{
				"api.ingress.consul.",
				"api.ingress.dc1.consul.",
				"db.ingress.consul.",
				"db.ingress.dc1.consul.",
			}
			for _, question := range questions {
				t.Run(question, func(t *testing.T) {
					m := new(dns.Msg)
					m.SetQuestion(question, dns.TypeA)

					c := new(dns.Client)
					in, _, err := c.Exchange(m, a.DNSAddr())
					require.Nil(t, err)
					require.Len(t, in.Answer, 1)

					cnameRec, ok := in.Answer[0].(*dns.A)
					require.True(t, ok)
					require.Equal(t, question, cnameRec.Hdr.Name)
					require.Equal(t, uint32(0), cnameRec.Hdr.Ttl)
					require.Equal(t, "127.0.0.1", cnameRec.A.String())
				})
			}
		})
	}
}

func TestDNS_ExternalServiceLookup(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with an external service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "www.google.com",
					Service: &structs.NodeService{
						Service: "db",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service
			questions := []string{
				"db.service.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 1 || len(in.Extra) > 0 {
					t.Fatalf("Bad: %#v", in)
				}

				srvRec, ok := in.Answer[0].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if srvRec.Port != 12345 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Target != "www.google.com." {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
			}
		})
	}
}

func TestDNS_ExternalServiceToConsulCNAMELookup(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		domain = "CONSUL."
		node_name = "test node"
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register the initial node with a service
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "web",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "web",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an external service pointing to the 'web' service
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "alias",
					Address:    "web.service.consul",
					Service: &structs.NodeService{
						Service: "alias",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly
			questions := []string{
				"alias.service.consul.",
				"alias.service.CoNsUl.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				srvRec, ok := in.Answer[0].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if srvRec.Port != 12345 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Target != "web.service.consul." {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}

				if len(in.Extra) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				aRec, ok := in.Extra[0].(*dns.A)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Name != "web.service.consul." {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.A.String() != "127.0.0.1" {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
			}
		})
	}
}

func TestDNS_ExternalServiceToConsulCNAMENestedLookup(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		node_name = "test-node"
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register the initial node with a service
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "web",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "web",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an external service pointing to the 'web' service
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "alias",
					Address:    "web.service.consul",
					Service: &structs.NodeService{
						Service: "alias",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an external service pointing to the 'alias' service
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "alias2",
					Address:    "alias.service.consul",
					Service: &structs.NodeService{
						Service: "alias2",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly
			questions := []string{
				"alias2.service.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				srvRec, ok := in.Answer[0].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if srvRec.Port != 12345 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Target != "alias.service.consul." {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if len(in.Extra) != 2 {
					t.Fatalf("Bad: %#v", in)
				}

				cnameRec, ok := in.Extra[0].(*dns.CNAME)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if cnameRec.Hdr.Name != "alias.service.consul." {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if cnameRec.Target != "web.service.consul." {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if cnameRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}

				aRec, ok := in.Extra[1].(*dns.A)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[1])
				}
				if aRec.Hdr.Name != "web.service.consul." {
					t.Fatalf("Bad: %#v", in.Extra[1])
				}
				if aRec.A.String() != "127.0.0.1" {
					t.Fatalf("Bad: %#v", in.Extra[1])
				}
				if aRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Extra[1])
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_ServiceAddress_A(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Address: "127.0.0.2",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "db",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []string{
				"db.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				srvRec, ok := in.Answer[0].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if srvRec.Port != 12345 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Target != "7f000002.addr.dc1.consul." {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}

				aRec, ok := in.Extra[0].(*dns.A)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Name != "7f000002.addr.dc1.consul." {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.A.String() != "127.0.0.2" {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
			}
		})
	}
}

func TestDNS_AltDomain_ServiceLookup_ServiceAddress_A(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		alt_domain = "test-domain"
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Address: "127.0.0.2",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "db",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []struct {
				ask        string
				wantDomain string
			}{
				{"db.service.consul.", "consul."},
				{id + ".query.consul.", "consul."},
				{"db.service.test-domain.", "test-domain."},
				{id + ".query.test-domain.", "test-domain."},
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question.ask, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				srvRec, ok := in.Answer[0].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if srvRec.Port != 12345 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Target != "7f000002.addr.dc1."+question.wantDomain {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}

				aRec, ok := in.Extra[0].(*dns.A)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Name != "7f000002.addr.dc1."+question.wantDomain {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.A.String() != "127.0.0.2" {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_ServiceAddress_SRV(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	recursor := makeRecursor(t, dns.Msg{
		Answer: []dns.RR{
			dnsCNAME("www.google.com", "google.com"),
			dnsA("google.com", "1.2.3.4"),
		},
	})
	defer recursor.Shutdown()

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		               recursors = ["`+recursor.Addr+`"]
		       `+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service whose address isn't an IP.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Address: "www.google.com",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			// Specify prepared query name containing "." to test
			// since that is technically supported (though atypical).
			var id string
			preparedQueryName := "query.name.with.dots"
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: preparedQueryName,
						Service: structs.ServiceQuery{
							Service: "db",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []string{
				"db.service.consul.",
				id + ".query.consul.",
				preparedQueryName + ".query.consul.",
				fmt.Sprintf("_%s._tcp.query.consul.", id),
				fmt.Sprintf("_%s._tcp.query.consul.", preparedQueryName),
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				srvRec, ok := in.Answer[0].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if srvRec.Port != 12345 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Target != "www.google.com." {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}

				// Should have google CNAME
				cnRec, ok := in.Extra[0].(*dns.CNAME)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if cnRec.Target != "google.com." {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}

				// Check we recursively resolve
				aRec, ok := in.Extra[1].(*dns.A)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[1])
				}
				if aRec.A.String() != "1.2.3.4" {
					t.Fatalf("Bad: %s", aRec.A.String())
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_ServiceAddressIPV6(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Address: "2607:20:4005:808::200e",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "db",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []string{
				"db.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				srvRec, ok := in.Answer[0].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if srvRec.Port != 12345 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Target != "2607002040050808000000000000200e.addr.dc1.consul." {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}

				aRec, ok := in.Extra[0].(*dns.AAAA)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Name != "2607002040050808000000000000200e.addr.dc1.consul." {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.AAAA.String() != "2607:20:4005:808::200e" {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
			}
		})
	}
}

func TestDNS_AltDomain_ServiceLookup_ServiceAddressIPV6(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		alt_domain = "test-domain"
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Address: "2607:20:4005:808::200e",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "db",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []struct {
				ask  string
				want string
			}{
				{"db.service.consul.", "2607002040050808000000000000200e.addr.dc1.consul."},
				{"db.service.test-domain.", "2607002040050808000000000000200e.addr.dc1.test-domain."},
				{id + ".query.consul.", "2607002040050808000000000000200e.addr.dc1.consul."},
				{id + ".query.test-domain.", "2607002040050808000000000000200e.addr.dc1.test-domain."},
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question.ask, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				srvRec, ok := in.Answer[0].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if srvRec.Port != 12345 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Target != question.want {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}

				aRec, ok := in.Extra[0].(*dns.AAAA)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Name != question.want {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.AAAA.String() != "2607:20:4005:808::200e" {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_WanTranslation(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a1 := NewTestAgent(t, `
		datacenter = "dc1"
		translate_wan_addrs = true
		acl_datacenter = ""
	`+experimentsHCL)
			defer a1.Shutdown()

			a2 := NewTestAgent(t, `
		datacenter = "dc2"
		translate_wan_addrs = true
		acl_datacenter = ""
	`+experimentsHCL)
			defer a2.Shutdown()

			// Join WAN cluster
			addr := fmt.Sprintf("127.0.0.1:%d", a1.Config.SerfPortWAN)
			_, err := a2.JoinWAN([]string{addr})
			require.NoError(t, err)
			retry.Run(t, func(r *retry.R) {
				require.Len(r, a1.WANMembers(), 2)
				require.Len(r, a2.WANMembers(), 2)
			})

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc2",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "db",
						},
					},
				}
				require.NoError(t, a2.RPC(context.Background(), "PreparedQuery.Apply", args, &id))
			}

			type testCase struct {
				nodeTaggedAddresses    map[string]string
				serviceAddress         string
				serviceTaggedAddresses map[string]structs.ServiceAddress

				dnsAddr string

				expectedPort    uint16
				expectedAddress string
				expectedARRName string
			}

			cases := map[string]testCase{
				"node-addr-from-dc1": {
					dnsAddr:         a1.config.DNSAddrs[0].String(),
					expectedPort:    8080,
					expectedAddress: "127.0.0.1",
					expectedARRName: "foo.node.dc2.consul.",
				},
				"node-wan-from-dc1": {
					dnsAddr: a1.config.DNSAddrs[0].String(),
					nodeTaggedAddresses: map[string]string{
						"wan": "127.0.0.2",
					},
					expectedPort:    8080,
					expectedAddress: "127.0.0.2",
					expectedARRName: "7f000002.addr.dc2.consul.",
				},
				"service-addr-from-dc1": {
					dnsAddr: a1.config.DNSAddrs[0].String(),
					nodeTaggedAddresses: map[string]string{
						"wan": "127.0.0.2",
					},
					serviceAddress:  "10.0.1.1",
					expectedPort:    8080,
					expectedAddress: "10.0.1.1",
					expectedARRName: "0a000101.addr.dc2.consul.",
				},
				"service-wan-from-dc1": {
					dnsAddr: a1.config.DNSAddrs[0].String(),
					nodeTaggedAddresses: map[string]string{
						"wan": "127.0.0.2",
					},
					serviceAddress: "10.0.1.1",
					serviceTaggedAddresses: map[string]structs.ServiceAddress{
						"wan": {
							Address: "198.18.0.1",
							Port:    80,
						},
					},
					expectedPort:    80,
					expectedAddress: "198.18.0.1",
					expectedARRName: "c6120001.addr.dc2.consul.",
				},
				"node-addr-from-dc2": {
					dnsAddr:         a2.config.DNSAddrs[0].String(),
					expectedPort:    8080,
					expectedAddress: "127.0.0.1",
					expectedARRName: "foo.node.dc2.consul.",
				},
				"node-wan-from-dc2": {
					dnsAddr: a2.config.DNSAddrs[0].String(),
					nodeTaggedAddresses: map[string]string{
						"wan": "127.0.0.2",
					},
					expectedPort:    8080,
					expectedAddress: "127.0.0.1",
					expectedARRName: "foo.node.dc2.consul.",
				},
				"service-addr-from-dc2": {
					dnsAddr: a2.config.DNSAddrs[0].String(),
					nodeTaggedAddresses: map[string]string{
						"wan": "127.0.0.2",
					},
					serviceAddress:  "10.0.1.1",
					expectedPort:    8080,
					expectedAddress: "10.0.1.1",
					expectedARRName: "0a000101.addr.dc2.consul.",
				},
				"service-wan-from-dc2": {
					dnsAddr: a2.config.DNSAddrs[0].String(),
					nodeTaggedAddresses: map[string]string{
						"wan": "127.0.0.2",
					},
					serviceAddress: "10.0.1.1",
					serviceTaggedAddresses: map[string]structs.ServiceAddress{
						"wan": {
							Address: "198.18.0.1",
							Port:    80,
						},
					},
					expectedPort:    8080,
					expectedAddress: "10.0.1.1",
					expectedARRName: "0a000101.addr.dc2.consul.",
				},
			}

			for name, tc := range cases {
				name := name
				tc := tc
				t.Run(name, func(t *testing.T) {
					// Register a remote node with a service. This is in a retry since we
					// need the datacenter to have a route which takes a little more time
					// beyond the join, and we don't have direct access to the router here.
					retry.Run(t, func(r *retry.R) {
						args := &structs.RegisterRequest{
							Datacenter:      "dc2",
							Node:            "foo",
							Address:         "127.0.0.1",
							TaggedAddresses: tc.nodeTaggedAddresses,
							Service: &structs.NodeService{
								Service:         "db",
								Address:         tc.serviceAddress,
								Port:            8080,
								TaggedAddresses: tc.serviceTaggedAddresses,
							},
						}

						var out struct{}
						require.NoError(r, a2.RPC(context.Background(), "Catalog.Register", args, &out))
					})

					// Look up the SRV record via service and prepared query.
					questions := []string{
						"db.service.dc2.consul.",
						id + ".query.dc2.consul.",
					}
					for _, question := range questions {
						m := new(dns.Msg)
						m.SetQuestion(question, dns.TypeSRV)

						c := new(dns.Client)

						addr := tc.dnsAddr
						in, _, err := c.Exchange(m, addr)
						require.NoError(t, err)
						require.Len(t, in.Answer, 1)
						srvRec, ok := in.Answer[0].(*dns.SRV)
						require.True(t, ok, "Bad: %#v", in.Answer[0])
						require.Equal(t, tc.expectedPort, srvRec.Port)

						aRec, ok := in.Extra[0].(*dns.A)
						require.True(t, ok, "Bad: %#v", in.Extra[0])
						require.Equal(t, tc.expectedARRName, aRec.Hdr.Name)
						require.Equal(t, tc.expectedAddress, aRec.A.String())
					}

					// Also check the A record directly
					for _, question := range questions {
						m := new(dns.Msg)
						m.SetQuestion(question, dns.TypeA)

						c := new(dns.Client)
						addr := tc.dnsAddr
						in, _, err := c.Exchange(m, addr)
						require.NoError(t, err)
						require.Len(t, in.Answer, 1)

						aRec, ok := in.Answer[0].(*dns.A)
						require.True(t, ok, "Bad: %#v", in.Answer[0])
						require.Equal(t, question, aRec.Hdr.Name)
						require.Equal(t, tc.expectedAddress, aRec.A.String())
					}
				})
			}
		})
	}
}

func TestDNS_ServiceLookup_CaseInsensitive(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	tests := []struct {
		name   string
		config string
	}{
		// UDP + EDNS
		{"normal", ""},
		{"cache", `dns_config{ allow_stale=true, max_stale="3h", use_cache=true, "cache_max_age"="3h"}`},
		{"cache-with-streaming", `
			rpc{
				enable_streaming=true
			}
			use_streaming_backend=true
			dns_config{ allow_stale=true, max_stale="3h", use_cache=true, "cache_max_age"="3h"}
		    `},
	}
	for _, tst := range tests {
		t.Run(fmt.Sprintf("A lookup %v", tst.name), func(t *testing.T) {
			for name, experimentsHCL := range getVersionHCL(true) {
				t.Run(name, func(t *testing.T) {
					a := NewTestAgent(t, fmt.Sprintf("%s %s", tst.config, experimentsHCL))
					defer a.Shutdown()
					testrpc.WaitForLeader(t, a.RPC, "dc1")

					// Register a node with a service.
					{
						args := &structs.RegisterRequest{
							Datacenter: "dc1",
							Node:       "foo",
							Address:    "127.0.0.1",
							Service: &structs.NodeService{
								Service: "Db",
								Tags:    []string{"Primary"},
								Port:    12345,
							},
						}

						var out struct{}
						if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
							t.Fatalf("err: %v", err)
						}
					}

					// Register an equivalent prepared query, as well as a name.
					var id string
					{
						args := &structs.PreparedQueryRequest{
							Datacenter: "dc1",
							Op:         structs.PreparedQueryCreate,
							Query: &structs.PreparedQuery{
								Name: "somequery",
								Service: structs.ServiceQuery{
									Service: "db",
								},
							},
						}
						if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
							t.Fatalf("err: %v", err)
						}
					}

					// Try some variations to make sure case doesn't matter.
					questions := []string{
						"primary.Db.service.consul.",
						"primary.db.service.consul.",
						"pRIMARY.dB.service.consul.",
						"PRIMARY.dB.service.consul.",
						"db.service.consul.",
						"DB.service.consul.",
						"Db.service.consul.",
						"somequery.query.consul.",
						"SomeQuery.query.consul.",
						"SOMEQUERY.query.consul.",
					}

					for _, question := range questions {
						m := new(dns.Msg)
						m.SetQuestion(question, dns.TypeSRV)

						c := new(dns.Client)
						retry.Run(t, func(r *retry.R) {
							in, _, err := c.Exchange(m, a.DNSAddr())
							if err != nil {
								r.Fatalf("err: %v", err)
							}

							if len(in.Answer) != 1 {
								r.Fatalf("question %v, empty lookup: %#v", question, in)
							}
						})
					}
				})
			}
		})
	}
}

// V2 DNS: we have deprecated support for service tags w/ periods
func TestDNS_ServiceLookup_TagPeriod(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(false) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register node
			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "foo",
				Address:    "127.0.0.1",
				Service: &structs.NodeService{
					Service: "db",
					Tags:    []string{"v1.primary"},
					Port:    12345,
				},
			}

			var out struct{}
			if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
				t.Fatalf("err: %v", err)
			}

			m1 := new(dns.Msg)
			m1.SetQuestion("v1.primary2.db.service.consul.", dns.TypeSRV)

			c1 := new(dns.Client)
			in, _, err := c1.Exchange(m1, a.DNSAddr())
			if err != nil {
				t.Fatalf("err: %v", err)
			}

			if len(in.Answer) != 0 {
				t.Fatalf("Bad: %#v", in)
			}

			m := new(dns.Msg)
			m.SetQuestion("v1.primary.db.service.consul.", dns.TypeSRV)

			c := new(dns.Client)
			in, _, err = c.Exchange(m, a.DNSAddr())
			if err != nil {
				t.Fatalf("err: %v", err)
			}

			if len(in.Answer) != 1 {
				t.Fatalf("Bad: %#v", in)
			}

			srvRec, ok := in.Answer[0].(*dns.SRV)
			if !ok {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if srvRec.Port != 12345 {
				t.Fatalf("Bad: %#v", srvRec)
			}
			if srvRec.Target != "foo.node.dc1.consul." {
				t.Fatalf("Bad: %#v", srvRec)
			}

			aRec, ok := in.Extra[0].(*dns.A)
			if !ok {
				t.Fatalf("Bad: %#v", in.Extra[0])
			}
			if aRec.Hdr.Name != "foo.node.dc1.consul." {
				t.Fatalf("Bad: %#v", in.Extra[0])
			}
			if aRec.A.String() != "127.0.0.1" {
				t.Fatalf("Bad: %#v", in.Extra[0])
			}
		})
	}
}

func TestDNS_ServiceLookup_PreparedQueryNamePeriod(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register a prepared query with a period in the name.
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "some.query.we.like",
						Service: structs.ServiceQuery{
							Service: "db",
						},
					},
				}

				var id string
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			m := new(dns.Msg)
			m.SetQuestion("some.query.we.like.query.consul.", dns.TypeSRV)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			if err != nil {
				t.Fatalf("err: %v", err)
			}

			if len(in.Answer) != 1 {
				t.Fatalf("Bad: %#v", in)
			}

			srvRec, ok := in.Answer[0].(*dns.SRV)
			if !ok {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if srvRec.Port != 12345 {
				t.Fatalf("Bad: %#v", srvRec)
			}
			if srvRec.Target != "foo.node.dc1.consul." {
				t.Fatalf("Bad: %#v", srvRec)
			}

			aRec, ok := in.Extra[0].(*dns.A)
			if !ok {
				t.Fatalf("Bad: %#v", in.Extra[0])
			}
			if aRec.Hdr.Name != "foo.node.dc1.consul." {
				t.Fatalf("Bad: %#v", in.Extra[0])
			}
			if aRec.A.String() != "127.0.0.1" {
				t.Fatalf("Bad: %#v", in.Extra[0])
			}
		})
	}
}

func TestDNS_ServiceLookup_Dedup(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a single node with multiple instances of a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args = &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						ID:      "db2",
						Service: "db",
						Tags:    []string{"replica"},
						Port:    12345,
					},
				}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args = &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						ID:      "db3",
						Service: "db",
						Tags:    []string{"replica"},
						Port:    12346,
					},
				}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "db",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query, make sure only
			// one IP is returned.
			questions := []string{
				"db.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeANY)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				aRec, ok := in.Answer[0].(*dns.A)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if aRec.A.String() != "127.0.0.1" {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_Dedup_SRV(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a single node with multiple instances of a service.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args = &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						ID:      "db2",
						Service: "db",
						Tags:    []string{"replica"},
						Port:    12345,
					},
				}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args = &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						ID:      "db3",
						Service: "db",
						Tags:    []string{"replica"},
						Port:    12346,
					},
				}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "db",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query, make sure only
			// one IP is returned and two unique ports are returned.
			questions := []string{
				"db.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 2 {
					t.Fatalf("Bad: %#v", in)
				}

				srvRec, ok := in.Answer[0].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if srvRec.Port != 12345 && srvRec.Port != 12346 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Target != "foo.node.dc1.consul." {
					t.Fatalf("Bad: %#v", srvRec)
				}

				srvRec, ok = in.Answer[1].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[1])
				}
				if srvRec.Port != 12346 && srvRec.Port != 12345 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Port == in.Answer[0].(*dns.SRV).Port {
					t.Fatalf("should be a different port")
				}
				if srvRec.Target != "foo.node.dc1.consul." {
					t.Fatalf("Bad: %#v", srvRec)
				}

				aRec, ok := in.Extra[0].(*dns.A)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Name != "foo.node.dc1.consul." {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.A.String() != "127.0.0.1" {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_FilterCritical(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register nodes with health checks in various states.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
					Check: &structs.HealthCheck{
						CheckID: "serf",
						Name:    "serf",
						Status:  api.HealthCritical,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args2 := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "bar",
					Address:    "127.0.0.2",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
					Check: &structs.HealthCheck{
						CheckID: "serf",
						Name:    "serf",
						Status:  api.HealthCritical,
					},
				}
				if err := a.RPC(context.Background(), "Catalog.Register", args2, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args3 := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "bar",
					Address:    "127.0.0.2",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
					Check: &structs.HealthCheck{
						CheckID:   "db",
						Name:      "db",
						ServiceID: "db",
						Status:    api.HealthCritical,
					},
				}
				if err := a.RPC(context.Background(), "Catalog.Register", args3, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args4 := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "baz",
					Address:    "127.0.0.3",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
				}
				if err := a.RPC(context.Background(), "Catalog.Register", args4, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args5 := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "quux",
					Address:    "127.0.0.4",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
					Check: &structs.HealthCheck{
						CheckID:   "db",
						Name:      "db",
						ServiceID: "db",
						Status:    api.HealthWarning,
					},
				}
				if err := a.RPC(context.Background(), "Catalog.Register", args5, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "db",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []string{
				"db.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeANY)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				// Only 4 and 5 are not failing, so we should get 2 answers
				if len(in.Answer) != 2 {
					t.Fatalf("Bad: %#v", in)
				}

				ips := make(map[string]bool)
				for _, resp := range in.Answer {
					aRec := resp.(*dns.A)
					ips[aRec.A.String()] = true
				}

				if !ips["127.0.0.3"] {
					t.Fatalf("Bad: %#v should contain 127.0.0.3 (state healthy)", in)
				}
				if !ips["127.0.0.4"] {
					t.Fatalf("Bad: %#v should contain 127.0.0.4 (state warning)", in)
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_OnlyFailing(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register nodes with all health checks in a critical state.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
					Check: &structs.HealthCheck{
						CheckID: "serf",
						Name:    "serf",
						Status:  api.HealthCritical,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args2 := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "bar",
					Address:    "127.0.0.2",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
					Check: &structs.HealthCheck{
						CheckID: "serf",
						Name:    "serf",
						Status:  api.HealthCritical,
					},
				}
				if err := a.RPC(context.Background(), "Catalog.Register", args2, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args3 := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "bar",
					Address:    "127.0.0.2",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
					Check: &structs.HealthCheck{
						CheckID:   "db",
						Name:      "db",
						ServiceID: "db",
						Status:    api.HealthCritical,
					},
				}
				if err := a.RPC(context.Background(), "Catalog.Register", args3, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "db",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []string{
				"db.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeANY)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				// All 3 are failing, so we should get 0 answers and an NXDOMAIN response
				if len(in.Answer) != 0 {
					t.Fatalf("Bad: %#v", in)
				}

				if in.Rcode != dns.RcodeNameError {
					t.Fatalf("Bad: %#v", in)
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_OnlyPassing(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		dns_config {
			only_passing = true
		}
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register nodes with health checks in various states.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "foo",
					Address:    "127.0.0.1",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
					Check: &structs.HealthCheck{
						CheckID:   "db",
						Name:      "db",
						ServiceID: "db",
						Status:    api.HealthPassing,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args2 := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "bar",
					Address:    "127.0.0.2",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
					Check: &structs.HealthCheck{
						CheckID:   "db",
						Name:      "db",
						ServiceID: "db",
						Status:    api.HealthWarning,
					},
				}

				if err := a.RPC(context.Background(), "Catalog.Register", args2, &out); err != nil {
					t.Fatalf("err: %v", err)
				}

				args3 := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "baz",
					Address:    "127.0.0.3",
					Service: &structs.NodeService{
						Service: "db",
						Tags:    []string{"primary"},
						Port:    12345,
					},
					Check: &structs.HealthCheck{
						CheckID:   "db",
						Name:      "db",
						ServiceID: "db",
						Status:    api.HealthCritical,
					},
				}

				if err := a.RPC(context.Background(), "Catalog.Register", args3, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service:     "db",
							OnlyPassing: true,
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []string{
				"db.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeANY)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				// Only 1 is passing, so we should only get 1 answer
				if len(in.Answer) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				resp := in.Answer[0]
				aRec := resp.(*dns.A)

				if aRec.A.String() != "127.0.0.1" {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
			}

			newCfg := *a.Config
			newCfg.DNSOnlyPassing = false
			err := a.reloadConfigInternal(&newCfg)
			require.NoError(t, err)

			// only_passing is now false. we should now get two nodes
			m := new(dns.Msg)
			m.SetQuestion("db.service.consul.", dns.TypeANY)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			require.NoError(t, err)

			require.Equal(t, 2, len(in.Answer))
			ips := []string{in.Answer[0].(*dns.A).A.String(), in.Answer[1].(*dns.A).A.String()}
			sort.Strings(ips)
			require.Equal(t, []string{"127.0.0.1", "127.0.0.2"}, ips)
		})
	}
}

func TestDNS_ServiceLookup_Randomize(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a large number of nodes.
			for i := 0; i < generateNumNodes; i++ {
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       fmt.Sprintf("foo%d", i),
					Address:    fmt.Sprintf("127.0.0.%d", i+1),
					Service: &structs.NodeService{
						Service: "web",
						Port:    8000,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "web",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query. Ensure the
			// response is randomized each time.
			questions := []string{
				"web.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				uniques := map[string]struct{}{}
				for i := 0; i < 10; i++ {
					m := new(dns.Msg)
					m.SetQuestion(question, dns.TypeANY)

					c := &dns.Client{Net: "udp"}
					in, _, err := c.Exchange(m, a.DNSAddr())
					if err != nil {
						t.Fatalf("err: %v", err)
					}

					// Response length should be truncated and we should get
					// an A record for each response.
					if len(in.Answer) != defaultNumUDPResponses {
						t.Fatalf("Bad: %#v", len(in.Answer))
					}

					// Collect all the names.
					var names []string
					for _, rec := range in.Answer {
						switch v := rec.(type) {
						case *dns.SRV:
							names = append(names, v.Target)
						case *dns.A:
							names = append(names, v.A.String())
						}
					}
					nameS := strings.Join(names, "|")

					// Tally the results.
					uniques[nameS] = struct{}{}
				}

				// Give some wiggle room. Since the responses are randomized and
				// there is a finite number of combinations, requiring 0
				// duplicates every test run eventually gives us failures.
				if len(uniques) < 2 {
					t.Fatalf("unique response ratio too low: %d/10\n%v", len(uniques), uniques)
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_Truncate(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		dns_config {
			enable_truncate = true
		}
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a large number of nodes.
			for i := 0; i < generateNumNodes; i++ {
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       fmt.Sprintf("foo%d", i),
					Address:    fmt.Sprintf("127.0.0.%d", i+1),
					Service: &structs.NodeService{
						Service: "web",
						Port:    8000,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "web",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query. Ensure the
			// response is truncated each time.
			questions := []string{
				"web.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeANY)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				// Check for the truncate bit
				if !in.Truncated {
					t.Fatalf("should have truncate bit")
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_LargeResponses(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		dns_config {
			enable_truncate = true
		}
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			longServiceName := "this-is-a-very-very-very-very-very-long-name-for-a-service"

			// Register a lot of nodes.
			for i := 0; i < 4; i++ {
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       fmt.Sprintf("foo%d", i),
					Address:    fmt.Sprintf("127.0.0.%d", i+1),
					Service: &structs.NodeService{
						Service: longServiceName,
						Tags:    []string{"primary"},
						Port:    12345,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: longServiceName,
						Service: structs.ServiceQuery{
							Service: longServiceName,
							Tags:    []string{"primary"},
						},
					},
				}
				var id string
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []string{
				"_" + longServiceName + "._primary.service.consul.",
				longServiceName + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if !in.Truncated {
					t.Fatalf("should have truncate bit")
				}

				// Make sure the response size is RFC 1035-compliant for UDP messages
				if in.Len() > 512 {
					t.Fatalf("Bad: %d", in.Len())
				}

				// We should only have two answers now
				if len(in.Answer) != 2 {
					t.Fatalf("Bad: %d", len(in.Answer))
				}

				// Make sure the ADDITIONAL section matches the ANSWER section.
				if len(in.Answer) != len(in.Extra) {
					t.Fatalf("Bad: %d vs. %d", len(in.Answer), len(in.Extra))
				}
				for i := 0; i < len(in.Answer); i++ {
					srv, ok := in.Answer[i].(*dns.SRV)
					if !ok {
						t.Fatalf("Bad: %#v", in.Answer[i])
					}

					a, ok := in.Extra[i].(*dns.A)
					if !ok {
						t.Fatalf("Bad: %#v", in.Extra[i])
					}

					if srv.Target != a.Hdr.Name {
						t.Fatalf("Bad: %#v %#v", srv, a)
					}
				}

				// Check for the truncate bit
				if !in.Truncated {
					t.Fatalf("should have truncate bit")
				}
			}
		})
	}
}

func testDNSServiceLookupResponseLimits(t *testing.T, answerLimit int, qType uint16,
	expectedService, expectedQuery, expectedQueryID int, additionalHCL string) (bool, error) {
	a := NewTestAgent(t, `
		node_name = "test-node"
		dns_config {
			udp_answer_limit = `+fmt.Sprintf("%d", answerLimit)+`
		}
	`+additionalHCL)
	defer a.Shutdown()
	testrpc.WaitForTestAgent(t, a.RPC, "dc1")

	choices := perfectlyRandomChoices(generateNumNodes, pctNodesWithIPv6)
	for i := 0; i < generateNumNodes; i++ {
		nodeAddress := fmt.Sprintf("127.0.0.%d", i+1)
		if choices[i] {
			nodeAddress = fmt.Sprintf("fe80::%d", i+1)
		}
		args := &structs.RegisterRequest{
			Datacenter: "dc1",
			Node:       fmt.Sprintf("foo%d", i),
			Address:    nodeAddress,
			Service: &structs.NodeService{
				Service: "api-tier",
				Port:    8080,
			},
		}

		var out struct{}
		if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
			return false, fmt.Errorf("err: %v", err)
		}
	}
	var id string
	{
		args := &structs.PreparedQueryRequest{
			Datacenter: "dc1",
			Op:         structs.PreparedQueryCreate,
			Query: &structs.PreparedQuery{
				Name: "api-tier",
				Service: structs.ServiceQuery{
					Service: "api-tier",
				},
			},
		}

		if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
			return false, fmt.Errorf("err: %v", err)
		}
	}

	// Look up the service directly and via prepared query.
	questions := []string{
		"api-tier.service.consul.",
		"api-tier.query.consul.",
		id + ".query.consul.",
	}
	for idx, question := range questions {
		m := new(dns.Msg)
		m.SetQuestion(question, qType)

		c := &dns.Client{Net: "udp"}
		in, _, err := c.Exchange(m, a.DNSAddr())
		if err != nil {
			return false, fmt.Errorf("err: %v", err)
		}

		switch idx {
		case 0:
			if (expectedService > 0 && len(in.Answer) != expectedService) ||
				(expectedService < -1 && len(in.Answer) < lib.AbsInt(expectedService)) {
				return false, fmt.Errorf("%d/%d answers received for type %v for %s, sz:=%d", len(in.Answer), answerLimit, qType, question, in.Len())
			}
		case 1:
			if (expectedQuery > 0 && len(in.Answer) != expectedQuery) ||
				(expectedQuery < -1 && len(in.Answer) < lib.AbsInt(expectedQuery)) {
				return false, fmt.Errorf("%d/%d answers received for type %v for %s, sz:=%d", len(in.Answer), answerLimit, qType, question, in.Len())
			}
		case 2:
			if (expectedQueryID > 0 && len(in.Answer) != expectedQueryID) ||
				(expectedQueryID < -1 && len(in.Answer) < lib.AbsInt(expectedQueryID)) {
				return false, fmt.Errorf("%d/%d answers received for type %v for %s, sz:=%d", len(in.Answer), answerLimit, qType, question, in.Len())
			}
		default:
			panic("abort")
		}
	}

	return true, nil
}

func checkDNSService(
	t *testing.T,
	generateNumNodes int,
	aRecordLimit int,
	qType uint16,
	expectedResultsCount int,
	udpSize uint16,
) {
	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		node_name = "test-node"
		dns_config {
			a_record_limit = `+fmt.Sprintf("%d", aRecordLimit)+`
			udp_answer_limit = `+fmt.Sprintf("%d", aRecordLimit)+`
		}
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForTestAgent(t, a.RPC, "dc1")

			choices := perfectlyRandomChoices(generateNumNodes, pctNodesWithIPv6)
			for i := 0; i < generateNumNodes; i++ {
				nodeAddress := fmt.Sprintf("127.0.0.%d", i+1)
				if choices[i] {
					nodeAddress = fmt.Sprintf("fe80::%d", i+1)
				}
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       fmt.Sprintf("foo%d", i),
					Address:    nodeAddress,
					Service: &structs.NodeService{
						Service: "api-tier",
						Port:    8080,
					},
				}

				var out struct{}
				require.NoError(t, a.RPC(context.Background(), "Catalog.Register", args, &out))
			}
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "api-tier",
						Service: structs.ServiceQuery{
							Service: "api-tier",
						},
					},
				}

				require.NoError(t, a.RPC(context.Background(), "PreparedQuery.Apply", args, &id))
			}

			// Look up the service directly and via prepared query.
			questions := []string{
				"api-tier.service.consul.",
				"api-tier.query.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				question := question
				t.Run("question: "+question, func(t *testing.T) {

					m := new(dns.Msg)

					m.SetQuestion(question, qType)
					protocol := "tcp"
					if udpSize > 0 {
						protocol = "udp"
					}
					if udpSize > 512 {
						m.SetEdns0(udpSize, true)
					}
					c := &dns.Client{Net: protocol, UDPSize: 8192}
					in, _, err := c.Exchange(m, a.DNSAddr())
					require.NoError(t, err)

					t.Logf("DNS Response for %+v - %+v", m, in)

					require.Equal(t, expectedResultsCount, len(in.Answer),
						"%d/%d answers received for type %v for %s (%s)", len(in.Answer), expectedResultsCount, qType, question, protocol)
				})
			}
		})
	}
}

func TestDNS_ServiceLookup_ARecordLimits(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	tests := []struct {
		name                   string
		aRecordLimit           int
		expectedAResults       int
		expectedAAAAResults    int
		expectedANYResults     int
		expectedSRVResults     int
		numNodesTotal          int
		udpSize                uint16
		_unused_udpAnswerLimit int // NOTE: this field is not used
	}{
		// UDP + EDNS
		{"udp-edns-1", 1, 1, 1, 1, 30, 30, 8192, 3},
		{"udp-edns-2", 2, 2, 2, 2, 30, 30, 8192, 3},
		{"udp-edns-3", 3, 3, 3, 3, 30, 30, 8192, 3},
		{"udp-edns-4", 4, 4, 4, 4, 30, 30, 8192, 3},
		{"udp-edns-5", 5, 5, 5, 5, 30, 30, 8192, 3},
		{"udp-edns-6", 6, 6, 6, 6, 30, 30, 8192, 3},
		{"udp-edns-max", 6, 2, 1, 3, 3, 3, 8192, 3},
		// All UDP without EDNS have a limit of 2 answers due to udpAnswerLimit
		// Even SRV records are limit to 2 records
		{"udp-limit-1", 1, 1, 0, 1, 1, 1, 512, 2},
		{"udp-limit-2", 2, 1, 1, 2, 2, 2, 512, 2},
		// AAAA results limited by size of payload
		{"udp-limit-3", 3, 1, 1, 2, 2, 2, 512, 2},
		{"udp-limit-4", 4, 1, 1, 2, 2, 2, 512, 2},
		{"udp-limit-5", 5, 1, 1, 2, 2, 2, 512, 2},
		{"udp-limit-6", 6, 1, 1, 2, 2, 2, 512, 2},
		{"udp-limit-max", 6, 1, 1, 2, 2, 2, 512, 2},
		// All UDP without EDNS and no udpAnswerLimit
		// Size of records is limited by UDP payload
		{"udp-1", 1, 1, 0, 1, 1, 1, 512, 0},
		{"udp-2", 2, 1, 1, 2, 2, 2, 512, 0},
		{"udp-3", 3, 1, 1, 2, 2, 2, 512, 0},
		{"udp-4", 4, 1, 1, 2, 2, 2, 512, 0},
		{"udp-5", 5, 1, 1, 2, 2, 2, 512, 0},
		{"udp-6", 6, 1, 1, 2, 2, 2, 512, 0},
		// Only 3 A and 3 SRV records on 512 bytes
		{"udp-max", 6, 1, 1, 2, 2, 2, 512, 0},

		{"tcp-1", 1, 1, 1, 1, 30, 30, 0, 0},
		{"tcp-2", 2, 2, 2, 2, 30, 30, 0, 0},
		{"tcp-3", 3, 3, 3, 3, 30, 30, 0, 0},
		{"tcp-4", 4, 4, 4, 4, 30, 30, 0, 0},
		{"tcp-5", 5, 5, 5, 5, 30, 30, 0, 0},
		{"tcp-6", 6, 6, 6, 6, 30, 30, 0, 0},
		{"tcp-max", 6, 1, 1, 2, 2, 2, 0, 0},
	}
	for _, test := range tests {
		test := test // capture loop var

		t.Run(test.name, func(t *testing.T) {

			// All those queries should have at max queriesLimited elements

			t.Run("A", func(t *testing.T) {
				checkDNSService(t, test.numNodesTotal, test.aRecordLimit, dns.TypeA, test.expectedAResults, test.udpSize)
			})

			t.Run("AAAA", func(t *testing.T) {
				checkDNSService(t, test.numNodesTotal, test.aRecordLimit, dns.TypeAAAA, test.expectedAAAAResults, test.udpSize)
			})

			t.Run("ANY", func(t *testing.T) {
				checkDNSService(t, test.numNodesTotal, test.aRecordLimit, dns.TypeANY, test.expectedANYResults, test.udpSize)
			})

			// No limits but the size of records for SRV records, since not subject to randomization issues
			t.Run("SRV", func(t *testing.T) {
				checkDNSService(t, test.expectedSRVResults, test.aRecordLimit, dns.TypeSRV, test.numNodesTotal, test.udpSize)
			})
		})
	}
}

func TestDNS_ServiceLookup_AnswerLimits(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {

			// Build a matrix of config parameters (udpAnswerLimit), and the
			// length of the response per query type and question.  Negative
			// values imply the test must return at least the abs(value) number
			// of records in the answer section.  This is required because, for
			// example, on OS-X and Linux, the number of answers returned in a
			// 512B response is different even though both platforms are x86_64
			// and using the same version of Go.
			//
			// TODO(sean@): Why is it not identical everywhere when using the
			// same compiler?
			tests := []struct {
				name                string
				udpAnswerLimit      int
				expectedAService    int
				expectedAQuery      int
				expectedAQueryID    int
				expectedAAAAService int
				expectedAAAAQuery   int
				expectedAAAAQueryID int
				expectedANYService  int
				expectedANYQuery    int
				expectedANYQueryID  int
			}{
				{"0", 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
				{"1", 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},
				{"2", 2, 2, 2, 2, 2, 2, 2, 2, 2, 2},
				{"3", 3, 3, 3, 3, 3, 3, 3, 3, 3, 3},
				{"4", 4, 4, 4, 4, 4, 4, 4, 4, 4, 4},
				{"5", 5, 5, 5, 5, 5, 5, 5, 5, 5, 5},
				{"6", 6, 6, 6, 6, 6, 6, 5, 6, 6, -5},
				{"7", 7, 7, 7, 6, 7, 7, 5, 7, 7, -5},
				{"8", 8, 8, 8, 6, 8, 8, 5, 8, 8, -5},
				{"9", 9, 8, 8, 6, 8, 8, 5, 8, 8, -5},
				{"20", 20, 8, 8, 6, 8, 8, 5, 8, -5, -5},
				{"30", 30, 8, 8, 6, 8, 8, 5, 8, -5, -5},
			}
			for _, test := range tests {
				test := test // capture loop var
				t.Run(fmt.Sprintf("A lookup %v", test), func(t *testing.T) {
					ok, err := testDNSServiceLookupResponseLimits(t, test.udpAnswerLimit, dns.TypeA, test.expectedAService, test.expectedAQuery, test.expectedAQueryID, experimentsHCL)
					if !ok {
						t.Fatalf("Expected service A lookup %s to pass: %v", test.name, err)
					}
				})

				t.Run(fmt.Sprintf("AAAA lookup %v", test), func(t *testing.T) {
					ok, err := testDNSServiceLookupResponseLimits(t, test.udpAnswerLimit, dns.TypeAAAA, test.expectedAAAAService, test.expectedAAAAQuery, test.expectedAAAAQueryID, experimentsHCL)
					if !ok {
						t.Fatalf("Expected service AAAA lookup %s to pass: %v", test.name, err)
					}
				})

				t.Run(fmt.Sprintf("ANY lookup %v", test), func(t *testing.T) {
					ok, err := testDNSServiceLookupResponseLimits(t, test.udpAnswerLimit, dns.TypeANY, test.expectedANYService, test.expectedANYQuery, test.expectedANYQueryID, experimentsHCL)
					if !ok {
						t.Fatalf("Expected service ANY lookup %s to pass: %v", test.name, err)
					}
				})
			}
		})
	}
}

func TestDNS_ServiceLookup_CNAME(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	recursor := makeRecursor(t, dns.Msg{
		Answer: []dns.RR{
			dnsCNAME("www.google.com", "google.com"),
			dnsA("google.com", "1.2.3.4"),
		},
	})
	defer recursor.Shutdown()

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		recursors = ["`+recursor.Addr+`"]
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a name for an address.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "google",
					Address:    "www.google.com",
					Service: &structs.NodeService{
						Service: "search",
						Port:    80,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "search",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []string{
				"search.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeANY)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				// Service CNAME, google CNAME, google A record
				if len(in.Answer) != 3 {
					t.Fatalf("Bad: %#v", in)
				}

				// Should have service CNAME
				cnRec, ok := in.Answer[0].(*dns.CNAME)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if cnRec.Target != "www.google.com." {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}

				// Should have google CNAME
				cnRec, ok = in.Answer[1].(*dns.CNAME)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[1])
				}
				if cnRec.Target != "google.com." {
					t.Fatalf("Bad: %#v", in.Answer[1])
				}

				// Check we recursively resolve
				if _, ok := in.Answer[2].(*dns.A); !ok {
					t.Fatalf("Bad: %#v", in.Answer[2])
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_ServiceAddress_CNAME(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	recursor := makeRecursor(t, dns.Msg{
		Answer: []dns.RR{
			dnsCNAME("www.google.com", "google.com"),
			dnsA("google.com", "1.2.3.4"),
		},
	})
	defer recursor.Shutdown()

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		recursors = ["`+recursor.Addr+`"]
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a name for an address.
			{
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       "google",
					Address:    "1.2.3.4",
					Service: &structs.NodeService{
						Service: "search",
						Port:    80,
						Address: "www.google.com",
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Register an equivalent prepared query.
			var id string
			{
				args := &structs.PreparedQueryRequest{
					Datacenter: "dc1",
					Op:         structs.PreparedQueryCreate,
					Query: &structs.PreparedQuery{
						Name: "test",
						Service: structs.ServiceQuery{
							Service: "search",
						},
					},
				}
				if err := a.RPC(context.Background(), "PreparedQuery.Apply", args, &id); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			// Look up the service directly and via prepared query.
			questions := []string{
				"search.service.consul.",
				id + ".query.consul.",
			}
			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeANY)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				// Service CNAME, google CNAME, google A record
				if len(in.Answer) != 3 {
					t.Fatalf("Bad: %#v", in)
				}

				// Should have service CNAME
				cnRec, ok := in.Answer[0].(*dns.CNAME)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if cnRec.Target != "www.google.com." {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}

				// Should have google CNAME
				cnRec, ok = in.Answer[1].(*dns.CNAME)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[1])
				}
				if cnRec.Target != "google.com." {
					t.Fatalf("Bad: %#v", in.Answer[1])
				}

				// Check we recursively resolve
				if _, ok := in.Answer[2].(*dns.A); !ok {
					t.Fatalf("Bad: %#v", in.Answer[2])
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_TTL(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `
		dns_config {
			service_ttl = {
				"d*" = "42s"
				"db" = "10s"
				"db*" = "66s"
				"*" = "5s"
			}
		allow_stale = true
		max_stale = "1s"
		}
	`+experimentsHCL)
			defer a.Shutdown()

			for idx, service := range []string{"db", "dblb", "dk", "api"} {
				nodeName := fmt.Sprintf("foo%d", idx)
				address := fmt.Sprintf("127.0.0.%d", idx)
				args := &structs.RegisterRequest{
					Datacenter: "dc1",
					Node:       nodeName,
					Address:    address,
					Service: &structs.NodeService{
						Service: service,
						Tags:    []string{"primary"},
						Port:    12345 + idx,
					},
				}

				var out struct{}
				if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
					t.Fatalf("err: %v", err)
				}
			}

			c := new(dns.Client)
			expectResult := func(dnsQuery string, expectedTTL uint32) {
				t.Run(dnsQuery, func(t *testing.T) {
					m := new(dns.Msg)
					m.SetQuestion(dnsQuery, dns.TypeSRV)

					in, _, err := c.Exchange(m, a.DNSAddr())
					if err != nil {
						t.Fatalf("err: %v", err)
					}

					if len(in.Answer) != 1 {
						t.Fatalf("Bad: %#v, len is %d", in, len(in.Answer))
					}

					srvRec, ok := in.Answer[0].(*dns.SRV)
					if !ok {
						t.Fatalf("Bad: %#v", in.Answer[0])
					}
					if srvRec.Hdr.Ttl != expectedTTL {
						t.Fatalf("Bad: %#v", in.Answer[0])
					}

					aRec, ok := in.Extra[0].(*dns.A)
					if !ok {
						t.Fatalf("Bad: %#v", in.Extra[0])
					}
					if aRec.Hdr.Ttl != expectedTTL {
						t.Fatalf("Bad: %#v", in.Extra[0])
					}
				})
			}
			// Should have its exact TTL
			expectResult("db.service.consul.", 10)
			// Should match db*
			expectResult("dblb.service.consul.", 66)
			// Should match d*
			expectResult("dk.service.consul.", 42)
			// Should match *
			expectResult("api.service.consul.", 5)
		})
	}
}

func TestDNS_ServiceLookup_SRV_RFC(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register node
			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "foo",
				Address:    "127.0.0.1",
				Service: &structs.NodeService{
					Service: "db",
					Tags:    []string{"primary"},
					Port:    12345,
				},
			}

			var out struct{}
			if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
				t.Fatalf("err: %v", err)
			}

			questions := []string{
				"_db._primary.service.dc1.consul.",
				"_db._primary.service.consul.",
				"_db._primary.dc1.consul.",
				"_db._primary.consul.",
			}

			for _, question := range questions {
				m := new(dns.Msg)
				m.SetQuestion(question, dns.TypeSRV)

				c := new(dns.Client)
				in, _, err := c.Exchange(m, a.DNSAddr())
				if err != nil {
					t.Fatalf("err: %v", err)
				}

				if len(in.Answer) != 1 {
					t.Fatalf("Bad: %#v", in)
				}

				srvRec, ok := in.Answer[0].(*dns.SRV)
				if !ok {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}
				if srvRec.Port != 12345 {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Target != "foo.node.dc1.consul." {
					t.Fatalf("Bad: %#v", srvRec)
				}
				if srvRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Answer[0])
				}

				aRec, ok := in.Extra[0].(*dns.A)
				if !ok {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Name != "foo.node.dc1.consul." {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.A.String() != "127.0.0.1" {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
				if aRec.Hdr.Ttl != 0 {
					t.Fatalf("Bad: %#v", in.Extra[0])
				}
			}
		})
	}
}

func TestDNS_ServiceLookup_SRV_RFC_TCP_Default(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register node
			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "foo",
				Address:    "127.0.0.1",
				Service: &structs.NodeService{
					Service: "db",
					Tags:    []string{"primary"},
					Port:    12345,
				},
			}

			var out struct{}
			if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
				t.Fatalf("err: %v", err)
			}

			questions := []string{
				"_db._tcp.service.dc1.consul.",
				"_db._tcp.service.consul.",
				"_db._tcp.dc1.consul.",
				"_db._tcp.consul.",
			}

			for _, question := range questions {
				t.Run(question, func(t *testing.T) {
					m := new(dns.Msg)
					m.SetQuestion(question, dns.TypeSRV)

					c := new(dns.Client)
					in, _, err := c.Exchange(m, a.DNSAddr())
					if err != nil {
						t.Fatalf("err: %v", err)
					}

					if len(in.Answer) != 1 {
						t.Fatalf("Bad: %#v", in)
					}

					srvRec, ok := in.Answer[0].(*dns.SRV)
					if !ok {
						t.Fatalf("Bad: %#v", in.Answer[0])
					}
					if srvRec.Port != 12345 {
						t.Fatalf("Bad: %#v", srvRec)
					}
					if srvRec.Target != "foo.node.dc1.consul." {
						t.Fatalf("Bad: %#v", srvRec)
					}
					if srvRec.Hdr.Ttl != 0 {
						t.Fatalf("Bad: %#v", in.Answer[0])
					}

					aRec, ok := in.Extra[0].(*dns.A)
					if !ok {
						t.Fatalf("Bad: %#v", in.Extra[0])
					}
					if aRec.Hdr.Name != "foo.node.dc1.consul." {
						t.Fatalf("Bad: %#v", in.Extra[0])
					}
					if aRec.A.String() != "127.0.0.1" {
						t.Fatalf("Bad: %#v", in.Extra[0])
					}
					if aRec.Hdr.Ttl != 0 {
						t.Fatalf("Bad: %#v", in.Extra[0])
					}
				})
			}
		})
	}

}

func initDNSToken(t *testing.T, rpc RPC) {
	t.Helper()

	reqToken := structs.ACLTokenSetRequest{
		Datacenter: "dc1",
		ACLToken: structs.ACLToken{
			SecretID:          "279d4735-f8ca-4d48-b5cc-c00a9713bbf8",
			Policies:          nil,
			TemplatedPolicies: []*structs.ACLTemplatedPolicy{{TemplateName: "builtin/dns"}},
		},
		WriteRequest: structs.WriteRequest{Token: "root"},
	}
	err := rpc.RPC(context.Background(), "ACL.TokenSet", &reqToken, &structs.ACLToken{})
	require.NoError(t, err)
}

func TestDNS_ServiceLookup_FilterACL(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	tests := []struct {
		token   string
		results int
	}{
		{"root", 1},
		{"anonymous", 0},
		{"dns", 1},
	}
	for _, tt := range tests {
		t.Run("ACLToken == "+tt.token, func(t *testing.T) {
			hcl := `
				primary_datacenter = "dc1"

				acl {
					enabled = true
					default_policy = "deny"
					down_policy = "deny"

					tokens {
						initial_management = "root"
`
			if tt.token == "dns" {
				// Create a UUID for dns token since it doesn't have an alias
				dnsToken := "279d4735-f8ca-4d48-b5cc-c00a9713bbf8"

				hcl = hcl + `
						default = "anonymous"
						dns = "` + dnsToken + `"
`
			} else {
				hcl = hcl + `
						default = "` + tt.token + `"
`
			}

			hcl = hcl + `
					}
				}
			`

			for name, experimentsHCL := range getVersionHCL(true) {
				t.Run(name, func(t *testing.T) {
					a := NewTestAgent(t, hcl+experimentsHCL)
					defer a.Shutdown()
					testrpc.WaitForLeader(t, a.RPC, "dc1")

					if tt.token == "dns" {
						initDNSToken(t, a)
					}

					// Register a service
					args := &structs.RegisterRequest{
						Datacenter: "dc1",
						Node:       "foo",
						Address:    "127.0.0.1",
						Service: &structs.NodeService{
							Service: "foo",
							Port:    12345,
						},
						WriteRequest: structs.WriteRequest{Token: "root"},
					}
					var out struct{}
					if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
						t.Fatalf("err: %v", err)
					}

					// Set up the DNS query
					c := new(dns.Client)
					m := new(dns.Msg)
					m.SetQuestion("foo.service.consul.", dns.TypeA)

					in, _, err := c.Exchange(m, a.DNSAddr())
					if err != nil {
						t.Fatalf("err: %v", err)
					}
					if len(in.Answer) != tt.results {
						t.Fatalf("Bad: %#v", in)
					}
				})
			}
		})
	}
}

func TestDNS_ServiceLookup_MetaTXT(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `dns_config = { enable_additional_node_meta_txt = true } `+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "bar",
				Address:    "127.0.0.1",
				NodeMeta: map[string]string{
					"key": "value",
				},
				Service: &structs.NodeService{
					Service: "db",
					Tags:    []string{"primary"},
					Port:    12345,
				},
			}

			var out struct{}
			if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
				t.Fatalf("err: %v", err)
			}

			m := new(dns.Msg)
			m.SetQuestion("db.service.consul.", dns.TypeSRV)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			if err != nil {
				t.Fatalf("err: %v", err)
			}

			wantAdditional := []dns.RR{
				&dns.A{
					Hdr: dns.RR_Header{Name: "bar.node.dc1.consul.", Rrtype: dns.TypeA, Class: dns.ClassINET, Rdlength: 0x4},
					A:   []byte{0x7f, 0x0, 0x0, 0x1}, // 127.0.0.1
				},
				&dns.TXT{
					Hdr: dns.RR_Header{Name: "bar.node.dc1.consul.", Rrtype: dns.TypeTXT, Class: dns.ClassINET, Rdlength: 0xa},
					Txt: []string{"key=value"},
				},
			}
			require.Equal(t, wantAdditional, in.Extra)
		})
	}
}

func TestDNS_ServiceLookup_SuppressTXT(t *testing.T) {
	if testing.Short() {
		t.Skip("too slow for testing.Short")
	}

	for name, experimentsHCL := range getVersionHCL(true) {
		t.Run(name, func(t *testing.T) {
			a := NewTestAgent(t, `dns_config = { enable_additional_node_meta_txt = false } `+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register a node with a service.
			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "bar",
				Address:    "127.0.0.1",
				NodeMeta: map[string]string{
					"key": "value",
				},
				Service: &structs.NodeService{
					Service: "db",
					Tags:    []string{"primary"},
					Port:    12345,
				},
			}

			var out struct{}
			if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
				t.Fatalf("err: %v", err)
			}

			m := new(dns.Msg)
			m.SetQuestion("db.service.consul.", dns.TypeSRV)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			if err != nil {
				t.Fatalf("err: %v", err)
			}

			wantAdditional := []dns.RR{
				&dns.A{
					Hdr: dns.RR_Header{Name: "bar.node.dc1.consul.", Rrtype: dns.TypeA, Class: dns.ClassINET, Rdlength: 0x4},
					A:   []byte{0x7f, 0x0, 0x0, 0x1}, // 127.0.0.1
				},
			}
			require.Equal(t, wantAdditional, in.Extra)
		})
	}
}