add Apex function, to access a zonesapex

zone.go

@@ -3,6 +3,7 @@ package dns
 // A structure for handling zone data
 
 import (
+	"fmt"
 	"github.com/miekg/radix"
 	"math/rand"
 	"runtime"
@@ -356,6 +357,23 @@ func (z *Zone) RemoveRRset(s string, t uint16) error {
 	return nil
 }
 
+// Apex returns the zone's apex records (SOA, NS and possibly other). If the
+// apex can not be found (thereby making it an illegal DNS zone) it returns nil.
+// Updating the zone's SOA serial, provided the apex exists:
+//
+//	z.Apex.RR[TypeSOA][0].(*RR_SOA).Serial++
+//
+// Note the a) this increment is not protected by locks and b) if you use DNSSEC
+// you MUST resign the SOA record.
+func (z *Zone) Apex() *ZoneData {
+	apex, e := z.Find(z.Origin)
+	if !e {
+		fmt.Printf("%#v\n", apex)
+		return nil
+	}
+	return apex
+}
+
 // Find looks up the ownername s in the zone and returns the
 // data and true when an exact match is found. If an exact find isn't
 // possible the first parent node with a non-nil Value is returned and

zone_test.go

@@ -1,6 +1,7 @@
 package dns
 
 import (
+	"os"
 	"testing"
 )
 
@@ -20,6 +21,32 @@ func TestRadixName(t *testing.T) {
 	}
 }
 
+func TestApex(t *testing.T) {
+	f, err := os.Open("t/miek.nl.signed_test")
+	if err != nil {
+		t.Logf("Failed to open zone file")
+		t.Fail()
+	}
+	defer f.Close()
+	z := NewZone("miek.nl.")
+	to := ParseZone(f, "miek.nl.", "t/miek.nl.signed_test")
+	for rr := range to {
+		if rr.Error == nil {
+			z.Insert(rr.RR)
+		} else {
+			t.Logf("Error %s\n", rr.Error.Error())
+		}
+	}
+	apex := z.Apex()
+	if apex == nil {
+		t.Fatalf("Apex not found")
+	}
+	t.Logf("Apex found %s", apex.RR[TypeSOA][0].String())
+	apex.RR[TypeSOA][0].(*RR_SOA).Serial++
+	apex = z.Apex()
+	t.Logf("Apex found %s", z.Apex().RR[TypeSOA][0].String())
+}
+
 func TestInsert(t *testing.T) {
 	z := NewZone("miek.nl.")
 	mx, _ := NewRR("foo.miek.nl. MX 10 mx.miek.nl.")