libknot: add knot_dname_in()

src/libknot/dname.c

@@ -453,6 +453,13 @@ bool knot_dname_is_sub(const knot_dname_t *sub, const knot_dname_t *domain)
 
 /*----------------------------------------------------------------------------*/
 
+bool knot_dname_in(const knot_dname_t *domain, const knot_dname_t *sub)
+{
+	return knot_dname_is_equal(domain, sub) || knot_dname_is_sub(sub, domain);
+}
+
+/*----------------------------------------------------------------------------*/
+
 bool knot_dname_is_wildcard(const knot_dname_t *name)
 {
 	assert(name != NULL);

src/libknot/dname.h

@@ -191,6 +191,17 @@ int knot_dname_realsize(const knot_dname_t *name, const uint8_t *pkt);
  */
 bool knot_dname_is_sub(const knot_dname_t *sub, const knot_dname_t *domain);
 
+/*!
+ * \brief Check if the domain name is a subdomain of or equal to other.
+ *
+ * \param domain Domain name to be the possible parent domain.
+ * \param sub Domain name to be the possible subdomain.
+ *
+ * \retval true \a sub us a subdomain or equal to \a domain.
+ * \retval false otherwise.
+ */
+bool knot_dname_in(const knot_dname_t *domain, const knot_dname_t *sub);
+
 /*!
  * \brief Checks if the domain name is a wildcard.
  *