middleware/kubernetes: fix aaaa response (#780)

* fix aaaa response

* unit tests

middleware/kubernetes/handler.go

@@ -57,7 +57,7 @@ func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.M
 				path = strings.Join(dns.SplitDomainName(path)[1:], ".")
 				newstate := state.NewWithQuestion(strings.Join([]string{name, path}, "."), state.QType())
 				records, extra, _, err = k.routeRequest(zone, newstate)
-				if !k.IsNameError(err) {
+				if !k.IsNameError(err) && len(records) > 0 {
 					records = append(records, nil)
 					copy(records[1:], records)
 					records[0] = newCNAME(origQName, records[0].Header().Name, records[0].Header().Ttl)
@@ -79,7 +79,7 @@ func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.M
 			// Search . in this middleware
 			newstate := state.NewWithQuestion(strings.Join([]string{name, "."}, ""), state.QType())
 			records, extra, _, err = k.routeRequest(zone, newstate)
-			if !k.IsNameError(err) {
+			if !k.IsNameError(err) && len(records) > 0 {
 				records = append(records, nil)
 				copy(records[1:], records)
 				records[0] = newCNAME(origQName, records[0].Header().Name, records[0].Header().Ttl)

middleware/kubernetes/handler_test.go

@@ -81,6 +81,22 @@ var dnsTestCases = map[string](*test.Case){
 			test.CNAME("svc0.testns.fed.svc.cluster.local.	0	IN	CNAME	svc0.testns.fed.svc.fd-az.fd-r.federal.test."),
 		},
 	},
+	"AAAA Service (existing service)": {
+		Qname: "svc1.testns.svc.cluster.local.", Qtype: dns.TypeAAAA,
+		Rcode:  dns.RcodeSuccess,
+		Answer: []dns.RR{},
+		Ns: []dns.RR{
+			test.SOA("cluster.local.	300	IN	SOA	ns.dns.cluster.local. hostmaster.cluster.local. 1499347823 7200 1800 86400 60"),
+		},
+	},
+	"AAAA Service (non-existing service)": {
+		Qname: "svc0.testns.svc.cluster.local.", Qtype: dns.TypeAAAA,
+		Rcode:  dns.RcodeNameError,
+		Answer: []dns.RR{},
+		Ns: []dns.RR{
+			test.SOA("cluster.local.	300	IN	SOA	ns.dns.cluster.local. hostmaster.cluster.local. 1499347823 7200 1800 86400 60"),
+		},
+	},
 }
 
 var autopathCases = map[string](*test.Case){

middleware/kubernetes/kubernetes.go

@@ -115,10 +115,7 @@ func (k *Kubernetes) Services(state request.Request, exact bool, opt middleware.
 		return nil, nil, e
 	}
 	switch state.Type() {
-	case "AAAA":
+	case "A", "AAAA", "CNAME":
-		// AAAA not implemented
-		return nil, nil, errNoItems
-	case "A", "CNAME":
 		if state.Type() == "A" && isDefaultNS(state.Name(), r) {
 			// If this is an A request for "ns.dns", respond with a "fake" record for coredns.
 			// SOA records always use this hardcoded name
@@ -126,6 +123,10 @@ func (k *Kubernetes) Services(state request.Request, exact bool, opt middleware.
 			return svcs, nil, nil
 		}
 		s, e := k.Entries(r)
+		if state.QType() == dns.TypeAAAA {
+			// AAAA not implemented
+			return nil, nil, e
+		}
 		return s, nil, e // Haven't implemented debug queries yet.
 	case "SRV":
 		s, e := k.Entries(r)
@@ -325,8 +326,8 @@ func (k *Kubernetes) parseRequest(lowerCasedName string, qtype uint16) (r record
 		}
 		offset = 2
 	}
-	if qtype == dns.TypeA && len(segs) == 4 {
+	if (qtype == dns.TypeA || qtype == dns.TypeAAAA) && len(segs) == 4 {
-		// This is an endpoint A record request. Get first element as endpoint.
+		// This is an endpoint A/AAAA record request. Get first element as endpoint.
 		r.endpoint = segs[0]
 		offset = 1
 	}