Fix #1685 (#1700)

Signed-off-by: Mario Kleinsasser <mario.kleinsasser@gmail.com>

Create separate function for zone check
Signed-off-by: Mario Kleinsasser <mario.kleinsasser@gmail.com>

Add tests for zone A records
Signed-off-by: Mario Kleinsasser <mario.kleinsasser@gmail.com>

Remove pointer from checkZoneForRecord func signature, Add documentation
Signed-off-by: Mario Kleinsasser <mario.kleinsasser@gmail.com>

Change apex to zone, Update readme information, Add additional tests
Signed-off-by: Mario Kleinsasser <mario.kleinsasser@gmail.com>

Change zone to apex
Signed-off-by: Mario Kleinsasser <mario.kleinsasser@gmail.com>

Change readme to reflect apex change
Signed-off-by: Mario Kleinsasser <mario.kleinsasser@gmail.com>

Correct code comment
Signed-off-by: Mario Kleinsasser <mario.kleinsasser@gmail.com>

Correct string join for apex.dns
Signed-off-by: Mario Kleinsasser <mario.kleinsasser@gmail.com>

plugin/backend_lookup.go

@@ -14,7 +14,7 @@ import (
 
 // A returns A records from Backend or an error.
 func A(b ServiceBackend, zone string, state request.Request, previousRecords []dns.RR, opt Options) (records []dns.RR, err error) {
-	services, err := b.Services(state, false, opt)
+	services, err := checkZoneForRecord(b, zone, state, opt)
 	if err != nil {
 		return nil, err
 	}
@@ -78,7 +78,7 @@ func A(b ServiceBackend, zone string, state request.Request, previousRecords []d
 
 // AAAA returns AAAA records from Backend or an error.
 func AAAA(b ServiceBackend, zone string, state request.Request, previousRecords []dns.RR, opt Options) (records []dns.RR, err error) {
-	services, err := b.Services(state, false, opt)
+	services, err := checkZoneForRecord(b, zone, state, opt)
 	if err != nil {
 		return nil, err
 	}
@@ -403,4 +403,37 @@ func newAddress(s msg.Service, name string, ip net.IP, what uint16) dns.RR {
 	return &dns.AAAA{Hdr: hdr, AAAA: ip}
 }
 
+func checkZoneForRecord(b ServiceBackend, zone string, state request.Request, opt Options) ([]msg.Service, error) {
+	var services []msg.Service
+	var err error
+	// if the zone name itself is queried we fake the query to search for a special entry
+	// this is equivalent to the NS search code
+	if state.Name() == zone {
+		old := state.QName()
+		state.Clear()
+		state.Req.Question[0].Name = dnsutil.Join([]string{"apex.dns", zone})
+
+		services, err = b.Services(state, false, opt)
+		if err != nil {
+			// it might be possible, that "apex.dns.zone" does not exists
+			// we set back the query and try it once again to restore the backward compatibility behavior
+			state.Req.Question[0].Name = old
+			services, err = b.Services(state, false, opt)
+			// if it still errors, we return the error
+			if err != nil {
+				return services, err
+			}
+		}
+
+		state.Req.Question[0].Name = old
+	} else {
+		services, err = b.Services(state, false, opt)
+		if err != nil {
+			return services, err
+		}
+	}
+
+	return services, err
+}
+
 const hostmaster = "hostmaster"

plugin/etcd/README.md

@@ -128,6 +128,48 @@ Querying with dig:
 reverse.skydns.local.
 ~~~
 
+### Zone name as A record
+
+The zone name itself can be used A record. This behavior can be achieved by writing special entries to the ETCD path of your zone. If your zone is named `skydns.local` for example, you can create an `A` record for this zone as follows:
+
+~~~
+% curl -XPUT http://127.0.0.1:2379/v2/keys/skydns/local/skydns/dns/apex -d value='{"host":"1.1.1.1","ttl":"60"}'
+~~~
+
+If you query the zone name itself, you will receive the created `A` record:
+
+~~~ sh
+% dig +short skydns.local @localhost
+1.1.1.1
+~~~
+
+If you would like to use DNS RR for the zone name, you can set the following:
+~~~
+% curl -XPUT http://127.0.0.1:2379/v2/keys/skydns/local/skydns/dns/apex/x1 -d value='{"host":"1.1.1.1","ttl":"60"}'
+% curl -XPUT http://127.0.0.1:2379/v2/keys/skydns/local/skydns/dns/apex/x2 -d value='{"host":"1.1.1.2","ttl":"60"}'
+~~~
+
+If you query the zone name now, you will get the following response:
+
+~~~ sh
+dig +short skydns.local @localhost
+1.1.1.1
+1.1.1.2
+~~~
+
+If you would like to use `AAAA` records for the zone name too, you can set the following:
+~~~
+% curl -XPUT http://127.0.0.1:2379/v2/keys/skydns/local/skydns/dns/apex/x3 -d value='{"host":"2003::8:1","ttl":"60"}'
+% curl -XPUT http://127.0.0.1:2379/v2/keys/skydns/local/skydns/dns/apex/x4 -d value='{"host":"2003::8:2","ttl":"60"}'
+~~~
+
+If you query the zone name now for `AAAA` now, you will get the following response:
+~~~ sh
+dig +short skydns.local AAAA @localhost
+2003::8:1
+2003::8:2
+~~~
+
 ## Bugs
 
 Only the etcdv2 protocol is supported.

plugin/etcd/lookup_test.go

@@ -43,6 +43,25 @@ var services = []*msg.Service{
 	// Nameservers.
 	{Host: "10.0.0.2", Key: "a.ns.dns.skydns.test."},
 	{Host: "10.0.0.3", Key: "b.ns.dns.skydns.test."},
+	// Zone name as A record (basic, return all)
+	{Host: "10.0.0.2", Key: "x.skydns_zonea.test."},
+	{Host: "10.0.0.3", Key: "y.skydns_zonea.test."},
+	// Zone name as A (single entry).
+	{Host: "10.0.0.2", Key: "x.skydns_zoneb.test."},
+	{Host: "10.0.0.3", Key: "y.skydns_zoneb.test."},
+	{Host: "10.0.0.4", Key: "apex.dns.skydns_zoneb.test."},
+	// A zone record (rr multiple entries).
+	{Host: "10.0.0.2", Key: "x.skydns_zonec.test."},
+	{Host: "10.0.0.3", Key: "y.skydns_zonec.test."},
+	{Host: "10.0.0.4", Key: "a1.apex.dns.skydns_zonec.test."},
+	{Host: "10.0.0.5", Key: "a2.apex.dns.skydns_zonec.test."},
+	// AAAA zone record (rr multiple entries mixed with A).
+	{Host: "10.0.0.2", Key: "x.skydns_zoned.test."},
+	{Host: "10.0.0.3", Key: "y.skydns_zoned.test."},
+	{Host: "10.0.0.4", Key: "a1.apex.dns.skydns_zoned.test."},
+	{Host: "10.0.0.5", Key: "a2.apex.dns.skydns_zoned.test."},
+	{Host: "2003::8:1", Key: "a3.apex.dns.skydns_zoned.test."},
+	{Host: "2003::8:2", Key: "a4.apex.dns.skydns_zoned.test."},
 	// Reverse.
 	{Host: "reverse.example.com", Key: "1.0.0.10.in-addr.arpa."}, // 10.0.0.1
 }
@@ -214,6 +233,43 @@ var dnsTestCases = []test.Case{
 		Qname: "skydns_extra.test.", Qtype: dns.TypeSOA,
 		Answer: []dns.RR{test.SOA("skydns_extra.test. 300 IN SOA ns.dns.skydns_extra.test. hostmaster.skydns_extra.test. 1460498836 14400 3600 604800 60")},
 	},
+	// A Record Test for backward compatibility for zone records
+	{
+		Qname: "skydns_zonea.test.", Qtype: dns.TypeA,
+		Answer: []dns.RR{
+			test.A("skydns_zonea.test. 300 A 10.0.0.2"),
+			test.A("skydns_zonea.test. 300 A 10.0.0.3"),
+		},
+	},
+	// A Record Test for single A zone record
+	{
+		Qname: "skydns_zoneb.test.", Qtype: dns.TypeA,
+		Answer: []dns.RR{test.A("skydns_zoneb.test. 300 A 10.0.0.4")},
+	},
+	// A Record Test for multiple A zone records
+	{
+		Qname: "skydns_zonec.test.", Qtype: dns.TypeA,
+		Answer: []dns.RR{
+			test.A("skydns_zonec.test. 300 A 10.0.0.4"),
+			test.A("skydns_zonec.test. 300 A 10.0.0.5"),
+		},
+	},
+	// A Record Test for multiple mixed A and AAAA records
+	{
+		Qname: "skydns_zoned.test.", Qtype: dns.TypeA,
+		Answer: []dns.RR{
+			test.A("skydns_zoned.test. 300 A 10.0.0.4"),
+			test.A("skydns_zoned.test. 300 A 10.0.0.5"),
+		},
+	},
+	// AAAA Record Test for multiple mixed A and AAAA records
+	{
+		Qname: "skydns_zoned.test.", Qtype: dns.TypeAAAA,
+		Answer: []dns.RR{
+			test.AAAA("skydns_zoned.test. 300 AAAA 2003::8:1"),
+			test.AAAA("skydns_zoned.test. 300 AAAA 2003::8:2"),
+		},
+	},
 	// Reverse lookup
 	{
 		Qname: "1.0.0.10.in-addr.arpa.", Qtype: dns.TypePTR,
@@ -233,7 +289,7 @@ func newEtcdPlugin() *Etcd {
 		Upstream:   upstream.Upstream{Forward: &p},
 		PathPrefix: "skydns",
 		Ctx:        context.Background(),
-		Zones:      []string{"skydns.test.", "skydns_extra.test.", "in-addr.arpa."},
+		Zones:      []string{"skydns.test.", "skydns_extra.test.", "skydns_zonea.test.", "skydns_zoneb.test.", "skydns_zonec.test.", "skydns_zoned.test.", "in-addr.arpa."},
 		Client:     client,
 	}
 }