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return an empty record when asked for an addr dns with type other then A, AAAA and ANY (#10401) 

* return an invalid record when asked for an addr dns with type other then A and AAAA

* add changelog

* fix ANY use case and add a test for it

* update changelog type

Co-authored-by: Daniel Nephin <dnephin@hashicorp.com>

* return empty response if the question record type do not match for addr

* set comment in the right place

* return A\AAAA record in extra section if record type is not A\AAAA for addr

* Fix failing test

* remove commented code

Co-authored-by: Daniel Nephin <dnephin@hashicorp.com>

* use require for test validation

* use variable to init struct

* fix failing test

* Update agent/dns.go

Co-authored-by: Daniel Nephin <dnephin@hashicorp.com>

* Update .changelog/10401.txt

Co-authored-by: Daniel Nephin <dnephin@hashicorp.com>

* Update agent/dns.go

Co-authored-by: Daniel Nephin <dnephin@hashicorp.com>

* Update agent/dns.go

Co-authored-by: Daniel Nephin <dnephin@hashicorp.com>

* Update agent/dns.go

Co-authored-by: Daniel Nephin <dnephin@hashicorp.com>

* fix compilation error

Co-authored-by: Daniel Nephin <dnephin@hashicorp.com>
This commit is contained in:
Dhia Ayachi 2021-06-24 20:44:44 -04:00 committed by GitHub
parent a1e7556af6
commit 8b967b3bb6
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 121 additions and 20 deletions
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3
.changelog/10401.txt Normal file
View File

@ -0,0 +1,3 @@
```release-note:bug
dns: return an empty answer when asked for an addr dns with type other then A and AAAA.
```

23
agent/dns.go
View File

@ -782,6 +782,7 @@ func (d *DNSServer) doDispatch(network string, remoteAddr net.Addr, req, resp *d
case "addr":
// <address>.addr.<suffixes>.<domain> - addr must be the second label, datacenter is optional
if len(queryParts) != 1 {
return invalid()
}
@ -793,8 +794,8 @@ func (d *DNSServer) doDispatch(network string, remoteAddr net.Addr, req, resp *d
if err != nil {
return invalid()
}
resp.Answer = append(resp.Answer, &dns.A{
//check if the query type is A for IPv4 or ANY
aRecord := &dns.A{
Hdr: dns.RR_Header{
Name: qName + d.domain,
Rrtype: dns.TypeA,
@ -802,15 +803,20 @@ func (d *DNSServer) doDispatch(network string, remoteAddr net.Addr, req, resp *d
Ttl: uint32(cfg.NodeTTL / time.Second),
},
A: ip,
})
}
if req.Question[0].Qtype != dns.TypeA && req.Question[0].Qtype != dns.TypeANY {
resp.Extra = append(resp.Answer, aRecord)
} else {
resp.Answer = append(resp.Answer, aRecord)
}
// IPv6
case 16:
ip, err := hex.DecodeString(queryParts[0])
if err != nil {
return invalid()
}
resp.Answer = append(resp.Answer, &dns.AAAA{
//check if the query type is AAAA for IPv6 or ANY
aaaaRecord := &dns.AAAA{
Hdr: dns.RR_Header{
Name: qName + d.domain,
Rrtype: dns.TypeAAAA,
@ -818,7 +824,12 @@ func (d *DNSServer) doDispatch(network string, remoteAddr net.Addr, req, resp *d
Ttl: uint32(cfg.NodeTTL / time.Second),
},
AAAA: ip,
})
}
if req.Question[0].Qtype != dns.TypeAAAA && req.Question[0].Qtype != dns.TypeANY {
resp.Extra = append(resp.Extra, aaaaRecord)
} else {
resp.Answer = append(resp.Answer, aaaaRecord)
}
}
}
return true

115
agent/dns_test.go
View File

@ -6044,7 +6044,7 @@ func TestDNS_AddressLookup(t *testing.T) {
}
for question, answer := range cases {
m := new(dns.Msg)
m.SetQuestion(question, dns.TypeSRV)
m.SetQuestion(question, dns.TypeA)
c := new(dns.Client)
in, _, err := c.Exchange(m, a.DNSAddr())
@ -6052,20 +6052,73 @@ func TestDNS_AddressLookup(t *testing.T) {
t.Fatalf("err: %v", err)
}
if len(in.Answer) != 1 {
t.Fatalf("Bad: %#v", in)
}
require.Len(t, in.Answer, 1)
require.Equal(t, dns.TypeA, in.Answer[0].Header().Rrtype)
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])
}
require.True(t, ok)
require.Equal(t, aRec.A.To4().String(), answer)
require.Zero(t, aRec.Hdr.Ttl)
}
}
func TestDNS_AddressLookupANY(t *testing.T) {
if testing.Short() {
t.Skip("too slow for testing.Short")
}
t.Parallel()
a := NewTestAgent(t, "")
defer a.Shutdown()
testrpc.WaitForLeader(t, a.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.TypeANY)
c := new(dns.Client)
in, _, err := c.Exchange(m, a.DNSAddr())
require.NoError(t, err)
require.Len(t, in.Answer, 1)
require.Equal(t, in.Answer[0].Header().Rrtype, dns.TypeA)
aRec, ok := in.Answer[0].(*dns.A)
require.True(t, ok)
require.Equal(t, aRec.A.To4().String(), answer)
require.Zero(t, aRec.Hdr.Ttl)
}
}
func TestDNS_AddressLookupInvalidType(t *testing.T) {
if testing.Short() {
t.Skip("too slow for testing.Short")
}
t.Parallel()
a := NewTestAgent(t, "")
defer a.Shutdown()
testrpc.WaitForLeader(t, a.RPC, "dc1")
// Look up the addresses
cases := map[string]string{
"7f000001.addr.dc1.consul.": "",
}
for question := range cases {
m := new(dns.Msg)
m.SetQuestion(question, dns.TypeSRV)
c := new(dns.Client)
in, _, err := c.Exchange(m, a.DNSAddr())
require.NoError(t, err)
require.Zero(t, in.Rcode)
require.Nil(t, in.Answer)
require.NotNil(t, in.Extra)
require.Len(t, in.Extra, 1)
}
}
@ -6086,7 +6139,7 @@ func TestDNS_AddressLookupIPV6(t *testing.T) {
}
for question, answer := range cases {
m := new(dns.Msg)
m.SetQuestion(question, dns.TypeSRV)
m.SetQuestion(question, dns.TypeAAAA)
c := new(dns.Client)
in, _, err := c.Exchange(m, a.DNSAddr())
@ -6098,6 +6151,9 @@ func TestDNS_AddressLookupIPV6(t *testing.T) {
t.Fatalf("Bad: %#v", in)
}
if in.Answer[0].Header().Rrtype != dns.TypeAAAA {
t.Fatalf("Invalid type: %#v", in.Answer[0])
}
aaaaRec, ok := in.Answer[0].(*dns.AAAA)
if !ok {
t.Fatalf("Bad: %#v", in.Answer[0])
@ -6111,6 +6167,37 @@ func TestDNS_AddressLookupIPV6(t *testing.T) {
}
}
func TestDNS_AddressLookupIPV6InvalidType(t *testing.T) {
if testing.Short() {
t.Skip("too slow for testing.Short")
}
t.Parallel()
a := NewTestAgent(t, "")
defer a.Shutdown()
testrpc.WaitForLeader(t, a.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 := range cases {
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.Answer != nil {
t.Fatalf("Bad: %#v", in)
}
}
}
// TestDNS_NonExistentDC_Server verifies NXDOMAIN is returned when
// Consul server agent is queried for a service in a non-existent
// domain.