Merge pull request #26 from brutella/service-enum

Respond to _services._dns-sd._udp.<domain> dns query

zone.go

@@ -33,6 +33,7 @@ type MDNSService struct {
 
 	serviceAddr  string // Fully qualified service address
 	instanceAddr string // Fully qualified instance address
+	enumAddr     string // _services._dns-sd._udp.<domain>
 }
 
 // validateFQDN returns an error if the passed string is not a fully qualified
@@ -123,6 +124,7 @@ func NewMDNSService(instance, service, domain, hostName string, port int, ips []
 		TXT:          txt,
 		serviceAddr:  fmt.Sprintf("%s.%s.", trimDot(service), trimDot(domain)),
 		instanceAddr: fmt.Sprintf("%s.%s.%s.", instance, trimDot(service), trimDot(domain)),
+		enumAddr:     fmt.Sprintf("_services._dns-sd._udp.%s.", trimDot(domain)),
 	}, nil
 }
 
@@ -134,6 +136,8 @@ func trimDot(s string) string {
 // Records returns DNS records in response to a DNS question.
 func (m *MDNSService) Records(q dns.Question) []dns.RR {
 	switch q.Name {
+	case m.enumAddr:
+		return m.serviceEnum(q)
 	case m.serviceAddr:
 		return m.serviceRecords(q)
 	case m.instanceAddr:
@@ -148,6 +152,26 @@ func (m *MDNSService) Records(q dns.Question) []dns.RR {
 	}
 }
 
+func (m *MDNSService) serviceEnum(q dns.Question) []dns.RR {
+	switch q.Qtype {
+	case dns.TypeANY:
+		fallthrough
+	case dns.TypePTR:
+		rr := &dns.PTR{
+			Hdr: dns.RR_Header{
+				Name:   q.Name,
+				Rrtype: dns.TypePTR,
+				Class:  dns.ClassINET,
+				Ttl:    defaultTTL,
+			},
+			Ptr: m.serviceAddr,
+		}
+		return []dns.RR{rr}
+	default:
+		return nil
+	}
+}
+
 // serviceRecords is called when the query matches the service name
 func (m *MDNSService) serviceRecords(q dns.Question) []dns.RR {
 	switch q.Qtype {

zone_test.go

@@ -256,3 +256,20 @@ func TestMDNSService_HostNameQuery(t *testing.T) {
 		}
 	}
 }
+
+func TestMDNSService_serviceEnum_PTR(t *testing.T) {
+	s := makeService(t)
+	q := dns.Question{
+		Name:  "_services._dns-sd._udp.local.",
+		Qtype: dns.TypePTR,
+	}
+	recs := s.Records(q)
+	if len(recs) != 1 {
+		t.Fatalf("bad: %v", recs)
+	}
+	if ptr, ok := recs[0].(*dns.PTR); !ok {
+		t.Errorf("recs[0] should be PTR record, got: %v, all records: %v", recs[0], recs)
+	} else if got, want := ptr.Ptr, "_http._tcp.local."; got != want {
+		t.Fatalf("bad PTR record %v: got %v, want %v", ptr, got, want)
+	}
+}