Implement NS queries to Etcd middleware

Copy and port the NS record stuff from SkyDNS. Slightly cleaner
implementation.

middleware/etcd/handler.go

@@ -57,9 +57,11 @@ func (e Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (i
 	case "SOA":
 		records = []dns.RR{e.SOA(zone, state)}
 	case "NS":
-		//TODO(miek): skydns had a thing that you specify this, should look for
-		//records otherwise synthesise them.
-		//records = e.NS(zone, state)
+		if state.Name() == zone {
+			records, extra, err = e.NS(zone, state)
+			break
+		}
+		fallthrough
 	default:
 		// Do a fake A lookup, so we can distinguish betwen NODATA and NXDOMAIN
 		_, err = e.A(zone, state, nil)

middleware/etcd/lookup.go

@@ -1,6 +1,7 @@
 package etcd
 
 import (
+	"fmt"
 	"math"
 	"net"
 	"time"
@@ -312,6 +313,35 @@ func (e Etcd) TXT(zone string, state middleware.State) (records []dns.RR, err er
 	return records, nil
 }
 
+func (e Etcd) NS(zone string, state middleware.State) (records, extra []dns.RR, err error) {
+	// NS record for this zone live in a special place, ns.dns.<zone>. Fake our lookup.
+	// only a tad bit fishy...
+	old := state.QName()
+	state.Req.Question[0].Name = "ns.dns." + zone
+	services, err := e.records(state, false)
+	if err != nil {
+		return nil, nil, err
+	}
+	state.Req.Question[0].Name = old
+
+	for _, serv := range services {
+		ip := net.ParseIP(serv.Host)
+		switch {
+		case ip == nil:
+			return nil, nil, fmt.Errorf("NS record must be an IP address: %s", serv.Host)
+		case ip.To4() != nil:
+			serv.Host = e.Domain(serv.Key)
+			records = append(records, serv.NewNS(state.QName()))
+			extra = append(extra, serv.NewA(serv.Host, ip.To4()))
+		case ip.To4() == nil:
+			serv.Host = e.Domain(serv.Key)
+			records = append(records, serv.NewNS(state.QName()))
+			extra = append(extra, serv.NewAAAA(serv.Host, ip.To16()))
+		}
+	}
+	return records, extra, nil
+}
+
 // SOA Record returns a SOA record.
 func (e Etcd) SOA(zone string, state middleware.State) *dns.SOA {
 	header := dns.RR_Header{Name: zone, Rrtype: dns.TypeSOA, Ttl: 300, Class: dns.ClassINET}
@@ -326,6 +356,8 @@ func (e Etcd) SOA(zone string, state middleware.State) *dns.SOA {
 	}
 }
 
+// NS returns the NS records from etcd.
+
 // TODO(miek): DNSKEY and friends... intercepted by the DNSSEC middleware?
 
 func isDuplicateCNAME(r *dns.CNAME, records []dns.RR) bool {

middleware/etcd/lookup_test.go

@@ -30,6 +30,9 @@ var services = []*msg.Service{
 	// Cname loop
 	{Host: "a.cname.skydns.test", Key: "b.cname.skydns.test."},
 	{Host: "b.cname.skydns.test", Key: "a.cname.skydns.test."},
+	// Nameservers.
+	{Host: "10.0.0.2", Key: "a.ns.dns.skydns.test."},
+	{Host: "10.0.0.3", Key: "b.ns.dns.skydns.test."},
 }
 
 var dnsTestCases = []test.Case{
@@ -170,10 +173,31 @@ var dnsTestCases = []test.Case{
 		Qname: "skydns.test.", Qtype: dns.TypeSOA,
 		Answer: []dns.RR{test.SOA("skydns.test.	300	IN	SOA	ns.dns.skydns.test. hostmaster.skydns.test. 1460498836 14400 3600 604800 60")},
 	},
-	// TODO(miek)
-	// {
-	// Qname: "skydns.test.", Qtype: dns.TypeNS,
-	// },
+	// NS Record Test
+	{
+		Qname: "skydns.test.", Qtype: dns.TypeNS,
+		Answer: []dns.RR{
+			test.NS("skydns.test. 300 NS a.ns.dns.skydns.test."),
+			test.NS("skydns.test. 300 NS b.ns.dns.skydns.test."),
+		},
+		Extra: []dns.RR{
+			test.A("a.ns.dns.skydns.test. 300 A 10.0.0.2"),
+			test.A("b.ns.dns.skydns.test. 300 A 10.0.0.3"),
+		},
+	},
+	// NS Record Test
+	{
+		Qname: "a.skydns.test.", Qtype: dns.TypeNS, Rcode: dns.RcodeNameError,
+		Ns: []dns.RR{test.SOA("skydns.test.	300	IN	SOA	ns.dns.skydns.test. hostmaster.skydns.test. 1460498836 14400 3600 604800 60")},
+	},
+	// A Record For NS Record Test
+	{
+		Qname: "ns.dns.skydns.test.", Qtype: dns.TypeA,
+		Answer: []dns.RR{
+			test.A("ns.dns.skydns.test. 300 A 10.0.0.2"),
+			test.A("ns.dns.skydns.test. 300 A 10.0.0.3"),
+		},
+	},
 	{
 		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")},

middleware/etcd/msg/service.go

@@ -71,6 +71,12 @@ func (s *Service) NewTXT(name string) *dns.TXT {
 	return &dns.TXT{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: s.Ttl}, Txt: split255(s.Text)}
 }
 
+// NewNS returns a new NS record based on the Service.
+func (s *Service) NewNS(name string) *dns.NS {
+	host := targetStrip(dns.Fqdn(s.Host), s.TargetStrip)
+	return &dns.NS{Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeNS, Class: dns.ClassINET, Ttl: s.Ttl}, Ns: host}
+}
+
 // Group checks the services in sx, it looks for a Group attribute on the shortest
 // keys. If there are multiple shortest keys *and* the group attribute disagrees (and
 // is not empty), we don't consider it a group.

middleware/etcd/setup_test.go

@@ -16,6 +16,7 @@ import (
 	"github.com/miekg/coredns/middleware/etcd/singleflight"
 	"github.com/miekg/coredns/middleware/proxy"
 	"github.com/miekg/coredns/middleware/test"
+	"github.com/miekg/dns"
 
 	etcdc "github.com/coreos/etcd/client"
 	"golang.org/x/net/context"
@@ -69,7 +70,7 @@ func TestLookup(t *testing.T) {
 		rec := middleware.NewResponseRecorder(&test.ResponseWriter{})
 		_, err := etc.ServeDNS(ctx, rec, m)
 		if err != nil {
-			t.Errorf("expected no error, got %v\n", err)
+			t.Errorf("expected no error, got: %v for %s %s\n", err, m.Question[0].Name, dns.Type(m.Question[0].Qtype))
 			return
 		}
 		resp := rec.Msg()