Add check for \0 bytes in QNAME labels

src/knot/zone/contents.c

@@ -319,7 +319,6 @@ int zone_contents_find_dname(const zone_contents_t *zone,
 		return found;
 	}
 
-	*match = node;
 	if (previous != NULL) { // Null previous means zone not adjusted yet.
 		assert(prev);
 		*previous = prev;
@@ -327,10 +326,12 @@ int zone_contents_find_dname(const zone_contents_t *zone,
 
 	if (found == 1 && !null_byte_mismatch(node, name, name_nullbyte)) {
 		assert(node);
+		*match = node;
 		*closest = node;
 		return ZONE_NAME_FOUND;
 	} else {
 		assert(prev);
+		*match = NULL;
 		node = prev;
 		size_t matched_labels = knot_dname_matched_labels(node->owner, name);
 		while (matched_labels < knot_dname_labels(node->owner, NULL)) {