Add nsec3 search functions

zone.go

@@ -172,3 +172,32 @@ func (z Zone) LookupName(qname string, qclass, qtype uint16) (*ZRRset, os.Error)
 func intval(c, t uint16) int {
 	return int(c)*_CLASS + int(t)
 }
+
+// Needed for NSEC/NSEC3 in DNSSEC
+// SortInsert insert the string s in the already sorted
+// vector p. If s is already present it is not inserted again.
+func SortInsert(p *vector.StringVector, s string) {
+	sa := sort.StringArray(*p)
+	i := sa.Search(s)
+	if i < p.Len() && p.At(i) == s {
+		// element already there
+		return
+	}
+	p.Insert(i, s)
+}
+
+
+// Search searches the sorted vector p using binary search. If
+// the element s can not be found, the previous element is returned.
+func SortSearch(p *vector.StringVector, s string) string {
+	sa := sort.StringArray(*p)
+	i := sa.Search(s)
+	// with zones there must always be one before
+	if p.At(i) == s {
+		return s
+	}
+	if i > 0 {
+		i--
+	}
+	return p.At(i)
+}