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Give a valid service address in SRV lookup when it differs from the node's #2446

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merged 4 commits into from
Oct 28, 2016
Merged

Give a valid service address in SRV lookup when it differs from the node's #2446

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afd2d48
Give the service address in SRV lookup when it differs from the node's
kyhavlov Oct 28, 2016
ecff78a
Fix test cases
kyhavlov Oct 28, 2016
dfdd15d
Add a service address SRV lookup test for IPv6
kyhavlov Oct 28, 2016
109e0a6
Added tests for lookups on the 'addr.consul' domain
kyhavlov Oct 28, 2016
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67 changes: 66 additions & 1 deletion command/agent/dns.go
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Open in desktop
Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
package agent

import (
"encoding/hex"
"fmt"
"io"
"log"
Expand Down Expand Up @@ -357,6 +358,46 @@ PARSE:
query := strings.Join(labels[:n-1], ".")
d.preparedQueryLookup(network, datacenter, query, req, resp)

case "addr":
if n != 2 {
goto INVALID
}

switch len(labels[0]) / 2 {
// IPv4
case 4:
ip, err := hex.DecodeString(labels[0])
if err != nil {
goto INVALID
}

resp.Answer = append(resp.Answer, &dns.A{
Hdr: dns.RR_Header{
Name: qName + d.domain,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: uint32(d.config.NodeTTL / time.Second),
},
A: ip,
})
// IPv6
case 16:
ip, err := hex.DecodeString(labels[0])
if err != nil {
goto INVALID
}

resp.Answer = append(resp.Answer, &dns.AAAA{
Hdr: dns.RR_Header{
Name: qName + d.domain,
Rrtype: dns.TypeAAAA,
Class: dns.ClassINET,
Ttl: uint32(d.config.NodeTTL / time.Second),
},
AAAA: ip,
})
}

default:
// Store the DC, and re-parse
datacenter = labels[n-1]
Expand Down Expand Up @@ -820,8 +861,32 @@ func (d *DNSServer) serviceSRVRecords(dc string, nodes structs.CheckServiceNodes

// Add the extra record
records := d.formatNodeRecord(node.Node, addr, srvRec.Target, dns.TypeANY, ttl)

if records != nil {
resp.Extra = append(resp.Extra, records...)
// Use the node address if it doesn't differ from the service address
if addr == node.Node.Address {
resp.Extra = append(resp.Extra, records...)
} else {
// If it differs from the service address, give a special response in the
// 'addr.consul' domain with the service IP encoded in it. We have to do
// this because we can't put an IP in the target field of an SRV record.
switch record := records[0].(type) {
// IPv4
case *dns.A:
addr := hex.EncodeToString(record.A)

// Take the last 8 chars (4 bytes) of the encoded address to avoid junk bytes
srvRec.Target = fmt.Sprintf("%s.addr.%s.%s", addr[len(addr)-(net.IPv4len*2):], dc, d.domain)
record.Hdr.Name = srvRec.Target
resp.Extra = append(resp.Extra, record)

// IPv6
case *dns.AAAA:
srvRec.Target = fmt.Sprintf("%s.addr.%s.%s", hex.EncodeToString(record.AAAA), dc, d.domain)
record.Hdr.Name = srvRec.Target
resp.Extra = append(resp.Extra, record)
}
}
}
}
}
Expand Down
183 changes: 178 additions & 5 deletions command/agent/dns_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1039,7 +1039,7 @@ func TestDNS_ServiceLookup_ServiceAddress(t *testing.T) {
if srvRec.Port != 12345 {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Target != "foo.node.dc1.consul." {
if srvRec.Target != "7f000002.addr.dc1.consul." {
t.Fatalf("Bad: %#v", srvRec)
}
if srvRec.Hdr.Ttl != 0 {
Expand All @@ -1050,7 +1050,7 @@ func TestDNS_ServiceLookup_ServiceAddress(t *testing.T) {
if !ok {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.Hdr.Name != "foo.node.dc1.consul." {
if aRec.Hdr.Name != "7f000002.addr.dc1.consul." {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.A.String() != "127.0.0.2" {
Expand All @@ -1062,6 +1062,100 @@ func TestDNS_ServiceLookup_ServiceAddress(t *testing.T) {
}
}

func TestDNS_ServiceLookup_ServiceAddressIPV6(t *testing.T) {
dir, srv := makeDNSServer(t)
defer os.RemoveAll(dir)
defer srv.agent.Shutdown()

testutil.WaitForLeader(t, srv.agent.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{"master"},
Address: "2607:20:4005:808::200e",
Port: 12345,
},
}

var out struct{}
if err := srv.agent.RPC("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{
Service: structs.ServiceQuery{
Service: "db",
},
},
}
if err := srv.agent.RPC("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)
addr, _ := srv.agent.config.ClientListener("", srv.agent.config.Ports.DNS)
in, _, err := c.Exchange(m, addr.String())
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." {
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lol these hex names are 1337

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_WanAddress(t *testing.T) {
dir1, srv1 := makeDNSServerConfig(t,
func(c *Config) {
Expand Down Expand Up @@ -1157,7 +1251,7 @@ func TestDNS_ServiceLookup_WanAddress(t *testing.T) {
if !ok {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.Hdr.Name != "foo.node.dc2.consul." {
if aRec.Hdr.Name != "7f000002.addr.dc2.consul." {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if aRec.A.String() != "127.0.0.2" {
Expand Down Expand Up @@ -3193,15 +3287,15 @@ func TestDNS_PreparedQuery_Failover(t *testing.T) {
if !ok {
t.Fatalf("Bad: %#v", in.Answer[0])
}
if srv.Target != "foo.node.dc2.consul." {
if srv.Target != "7f000002.addr.dc2.consul." {
t.Fatalf("Bad: %#v", in.Answer[0])
}

a, ok := in.Extra[0].(*dns.A)
if !ok {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if a.Hdr.Name != "foo.node.dc2.consul." {
if a.Hdr.Name != "7f000002.addr.dc2.consul." {
t.Fatalf("Bad: %#v", in.Extra[0])
}
if a.A.String() != "127.0.0.2" {
Expand Down Expand Up @@ -3399,6 +3493,85 @@ func TestDNS_ServiceLookup_FilterACL(t *testing.T) {
}
}

func TestDNS_AddressLookup(t *testing.T) {
dir, srv := makeDNSServer(t)
defer os.RemoveAll(dir)
defer srv.agent.Shutdown()

testutil.WaitForLeader(t, srv.agent.RPC, "dc1")

// Look up the addresses
cases := map[string]string{
"7f000001.addr.dc1.consul.": "127.0.0.1",
}
for question, answer := range cases {
m := new(dns.Msg)
m.SetQuestion(question, dns.TypeSRV)

c := new(dns.Client)
addr, _ := srv.agent.config.ClientListener("", srv.agent.config.Ports.DNS)
in, _, err := c.Exchange(m, addr.String())
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.To4().String() != answer {
t.Fatalf("Bad: %#v", aRec)
}
if aRec.Hdr.Ttl != 0 {
t.Fatalf("Bad: %#v", in.Answer[0])
}
}
}

func TestDNS_AddressLookupIPV6(t *testing.T) {
dir, srv := makeDNSServer(t)
defer os.RemoveAll(dir)
defer srv.agent.Shutdown()

testutil.WaitForLeader(t, srv.agent.RPC, "dc1")

// Look up the addresses
cases := map[string]string{
"2607002040050808000000000000200e.addr.consul.": "2607:20:4005:808::200e",
"2607112040051808ffffffffffff200e.addr.consul.": "2607:1120:4005:1808:ffff:ffff:ffff:200e",
}
for question, answer := range cases {
m := new(dns.Msg)
m.SetQuestion(question, dns.TypeSRV)

c := new(dns.Client)
addr, _ := srv.agent.config.ClientListener("", srv.agent.config.Ports.DNS)
in, _, err := c.Exchange(m, addr.String())
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.To16().String() != answer {
t.Fatalf("Bad: %#v", aaaaRec)
}
if aaaaRec.Hdr.Ttl != 0 {
t.Fatalf("Bad: %#v", in.Answer[0])
}
}
}

func TestDNS_NonExistingLookup(t *testing.T) {
dir, srv := makeDNSServer(t)
defer os.RemoveAll(dir)
Expand Down