1 files changed, 29 insertions, 0 deletions
diff --git a/plugin/file/rrutil/util.go b/plugin/file/rrutil/util.go
new file mode 100644
index 000000000..63e447196
--- /dev/null
+++ b/plugin/file/rrutil/util.go
@@ -0,0 +1,29 @@
+// Package rrutil provides function to find certain RRs in slices.
+package rrutil
+
+import "github.com/miekg/dns"
+
+// SubTypeSignature returns the RRSIG for the subtype.
+func SubTypeSignature(rrs []dns.RR, subtype uint16) []dns.RR {
+	sigs := []dns.RR{}
+	// there may be multiple keys that have signed this subtype
+	for _, sig := range rrs {
+		if s, ok := sig.(*dns.RRSIG); ok {
+			if s.TypeCovered == subtype {
+				sigs = append(sigs, s)
+			}
+		}
+	}
+	return sigs
+}
+
+// CNAMEForType returns the RR that have the qtype from targets.
+func CNAMEForType(rrs []dns.RR, qtype uint16) []dns.RR {
+	ret := []dns.RR{}
+	for _, target := range rrs {
+		if target.Header().Rrtype == qtype {
+			ret = append(ret, target)
+		}
+	}
+	return ret
+}