checker: split monolithic rule into per-concern rules

checker/abstract.go

@@ -12,16 +12,10 @@ const (
 	serviceTypeNSOnlyOrigin = "abstract.NSOnlyOrigin"
 )
 
-// originPayload is a minimal local copy of services/abstract.Origin keeping
-// only the field this checker reads. The JSON tag matches the upstream wire
-// format ("ns").
-type originPayload struct {
-	NameServers []*dns.NS `json:"ns"`
-}
-
-// nsOnlyOriginPayload is a minimal local copy of
+// nsPayload is a minimal local copy of services/abstract.Origin and
 // services/abstract.NSOnlyOrigin keeping only the field this checker reads.
-type nsOnlyOriginPayload struct {
+// The JSON tag matches the upstream wire format ("ns").
+type nsPayload struct {
 	NameServers []*dns.NS `json:"ns"`
 }
 
@@ -29,14 +23,8 @@ type nsOnlyOriginPayload struct {
 // NSOnlyOrigin service payload.
 func nsFromService(svc *serviceMessage) []*dns.NS {
 	switch svc.Type {
-	case serviceTypeOrigin:
-		var o originPayload
-		if err := json.Unmarshal(svc.Service, &o); err != nil {
-			return nil
-		}
-		return o.NameServers
-	case serviceTypeNSOnlyOrigin:
-		var o nsOnlyOriginPayload
+	case serviceTypeOrigin, serviceTypeNSOnlyOrigin:
+		var o nsPayload
 		if err := json.Unmarshal(svc.Service, &o); err != nil {
 			return nil
 		}