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

package agent

import (
	"context"
	"testing"

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

	"github.com/hashicorp/consul/agent/structs"
	"github.com/hashicorp/consul/testrpc"
)

func TestDNS_NodeLookup(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",
				TaggedAddresses: map[string]string{
					"wan": "127.0.0.2",
				},
				NodeMeta: map[string]string{
					"key": "value",
				},
			}

			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("foo.node.consul.", dns.TypeANY)

			c := new(dns.Client)
			in, _, err := c.Exchange(m, a.DNSAddr())
			require.NoError(t, err)
			require.Len(t, in.Answer, 2)
			require.Len(t, in.Extra, 0)

			aRec, ok := in.Answer[0].(*dns.A)
			require.True(t, ok, "First answer is not an A record")
			require.Equal(t, "127.0.0.1", aRec.A.String())
			require.Equal(t, uint32(0), aRec.Hdr.Ttl)

			txt, ok := in.Answer[1].(*dns.TXT)
			require.True(t, ok, "Second answer is not a TXT record")
			require.Len(t, txt.Txt, 1)
			require.Equal(t, "key=value", txt.Txt[0])

			// Re-do the query, but only for an A RR

			m = new(dns.Msg)
			m.SetQuestion("foo.node.consul.", dns.TypeA)

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

			aRec, ok = in.Answer[0].(*dns.A)
			require.True(t, ok, "Answer is not an A record")
			require.Equal(t, "127.0.0.1", aRec.A.String())
			require.Equal(t, uint32(0), aRec.Hdr.Ttl)

			txt, ok = in.Extra[0].(*dns.TXT)
			require.True(t, ok, "Extra record is not a TXT record")
			require.Len(t, txt.Txt, 1)
			require.Equal(t, "key=value", txt.Txt[0])

			// Re-do the query, but specify the DC
			m = new(dns.Msg)
			m.SetQuestion("foo.node.dc1.consul.", dns.TypeANY)

			c = new(dns.Client)
			in, _, err = c.Exchange(m, a.DNSAddr())
			require.NoError(t, err)
			require.Len(t, in.Answer, 2)
			require.Len(t, in.Extra, 0)

			aRec, ok = in.Answer[0].(*dns.A)
			require.True(t, ok, "First answer is not an A record")
			require.Equal(t, "127.0.0.1", aRec.A.String())
			require.Equal(t, uint32(0), aRec.Hdr.Ttl)

			_, ok = in.Answer[1].(*dns.TXT)
			require.True(t, ok, "Second answer is not a TXT record")

			// lookup a non-existing node, we should receive a SOA
			m = new(dns.Msg)
			m.SetQuestion("nofoo.node.dc1.consul.", dns.TypeANY)

			c = new(dns.Client)
			in, _, err = c.Exchange(m, a.DNSAddr())
			require.NoError(t, err)
			require.Len(t, in.Ns, 1)
			soaRec, ok := in.Ns[0].(*dns.SOA)
			require.True(t, ok, "NS RR is not a SOA record")
			require.Equal(t, uint32(0), soaRec.Hdr.Ttl)
		})
	}
}

func TestDNS_NodeLookup_CaseInsensitive(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",
			}

			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("fOO.node.dc1.consul.", 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("empty lookup: %#v", in)
			}
		})
	}
}

// V2 DNS does not support node names with a period. This will be deprecated.
func TestDNS_NodeLookup_PeriodName(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 with period in name
			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "foo.bar",
				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("foo.bar.node.consul.", 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_NodeLookup_AAAA(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:       "bar",
				Address:    "::4242:4242",
			}

			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("bar.node.consul.", dns.TypeAAAA)

			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.AAAA)
			if !ok {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if aRec.AAAA.String() != "::4242:4242" {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if aRec.Hdr.Ttl != 0 {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
		})
	}
}

func TestDNS_NodeLookup_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"),
			dnsTXT("google.com", []string{"my_txt_value"}),
		},
	})
	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 node
			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "google",
				Address:    "www.google.com",
			}

			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("google.node.consul.", dns.TypeANY)
			m.SetEdns0(8192, true)

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

			wantAnswer := []dns.RR{
				&dns.CNAME{
					Hdr:    dns.RR_Header{Name: "google.node.consul.", Rrtype: dns.TypeCNAME, Class: dns.ClassINET, Ttl: 0, Rdlength: 0x10},
					Target: "www.google.com.",
				},
				&dns.CNAME{
					Hdr:    dns.RR_Header{Name: "www.google.com.", Rrtype: dns.TypeCNAME, Class: dns.ClassINET, Rdlength: 0x2},
					Target: "google.com.",
				},
				&dns.A{
					Hdr: dns.RR_Header{Name: "google.com.", Rrtype: dns.TypeA, Class: dns.ClassINET, Rdlength: 0x4},
					A:   []byte{0x1, 0x2, 0x3, 0x4}, // 1.2.3.4
				},
				&dns.TXT{
					Hdr: dns.RR_Header{Name: "google.com.", Rrtype: dns.TypeTXT, Class: dns.ClassINET, Rdlength: 0xd},
					Txt: []string{"my_txt_value"},
				},
			}
			require.Equal(t, wantAnswer, in.Answer)
		})
	}
}

func TestDNS_NodeLookup_TXT(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")

			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "google",
				Address:    "127.0.0.1",
				NodeMeta: map[string]string{
					"rfc1035-00": "value0",
					"key0":       "value1",
				},
			}

			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("google.node.consul.", dns.TypeTXT)

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

			// Should have the 1 TXT record reply
			if len(in.Answer) != 2 {
				t.Fatalf("Bad: %#v", in)
			}

			txtRec, ok := in.Answer[0].(*dns.TXT)
			if !ok {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if len(txtRec.Txt) != 1 {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if txtRec.Txt[0] != "value0" && txtRec.Txt[0] != "key0=value1" {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
		})
	}
}

func TestDNS_NodeLookup_TXT_DontSuppress(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")

			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "google",
				Address:    "127.0.0.1",
				NodeMeta: map[string]string{
					"rfc1035-00": "value0",
					"key0":       "value1",
				},
			}

			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("google.node.consul.", dns.TypeTXT)

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

			// Should have the 1 TXT record reply
			if len(in.Answer) != 2 {
				t.Fatalf("Bad: %#v", in)
			}

			txtRec, ok := in.Answer[0].(*dns.TXT)
			if !ok {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if len(txtRec.Txt) != 1 {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if txtRec.Txt[0] != "value0" && txtRec.Txt[0] != "key0=value1" {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
		})
	}
}

func TestDNS_NodeLookup_ANY(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")

			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "bar",
				Address:    "127.0.0.1",
				NodeMeta: map[string]string{
					"key": "value",
				},
			}

			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("bar.node.consul.", dns.TypeANY)

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

			wantAnswer := []dns.RR{
				&dns.A{
					Hdr: dns.RR_Header{Name: "bar.node.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.consul.", Rrtype: dns.TypeTXT, Class: dns.ClassINET, Rdlength: 0xa},
					Txt: []string{"key=value"},
				},
			}
			require.Equal(t, wantAnswer, in.Answer)
		})
	}
}

func TestDNS_NodeLookup_ANY_DontSuppressTXT(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")

			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "bar",
				Address:    "127.0.0.1",
				NodeMeta: map[string]string{
					"key": "value",
				},
			}

			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("bar.node.consul.", dns.TypeANY)

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

			wantAnswer := []dns.RR{
				&dns.A{
					Hdr: dns.RR_Header{Name: "bar.node.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.consul.", Rrtype: dns.TypeTXT, Class: dns.ClassINET, Rdlength: 0xa},
					Txt: []string{"key=value"},
				},
			}
			require.Equal(t, wantAnswer, in.Answer)
		})
	}
}

func TestDNS_NodeLookup_A_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")

			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "bar",
				Address:    "127.0.0.1",
				NodeMeta: map[string]string{
					"key": "value",
				},
			}

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

			m := new(dns.Msg)
			m.SetQuestion("bar.node.consul.", dns.TypeA)

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

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

			// ensure TXT RR suppression
			require.Len(t, in.Extra, 0)
		})
	}
}

func TestDNS_NodeLookup_TTL(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+`"]
		dns_config {
			node_ttl = "10s"
			allow_stale = true
			max_stale = "1s"
		}
	`+experimentsHCL)
			defer a.Shutdown()
			testrpc.WaitForLeader(t, a.RPC, "dc1")

			// Register node
			args := &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "foo",
				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("foo.node.consul.", 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])
			}
			if aRec.Hdr.Ttl != 10 {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}

			// Register node with IPv6
			args = &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "bar",
				Address:    "::4242:4242",
			}
			if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
				t.Fatalf("err: %v", err)
			}

			// Check an IPv6 record
			m = new(dns.Msg)
			m.SetQuestion("bar.node.consul.", dns.TypeANY)

			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)
			}

			aaaaRec, ok := in.Answer[0].(*dns.AAAA)
			if !ok {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if aaaaRec.AAAA.String() != "::4242:4242" {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
			if aaaaRec.Hdr.Ttl != 10 {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}

			// Register node with CNAME
			args = &structs.RegisterRequest{
				Datacenter: "dc1",
				Node:       "google",
				Address:    "www.google.com",
			}
			if err := a.RPC(context.Background(), "Catalog.Register", args, &out); err != nil {
				t.Fatalf("err: %v", err)
			}

			m = new(dns.Msg)
			m.SetQuestion("google.node.consul.", dns.TypeANY)

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

			// Should have the CNAME record + a few A records
			if len(in.Answer) < 2 {
				t.Fatalf("Bad: %#v", in)
			}

			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])
			}
			if cnRec.Hdr.Ttl != 10 {
				t.Fatalf("Bad: %#v", in.Answer[0])
			}
		})
	}
}