- if (domain_name && !avahi_is_valid_domain_name(domain_name))
- return avahi_server_set_errno(s, AVAHI_ERR_INVALID_DOMAIN_NAME);
+ AVAHI_CHECK_VALIDITY(s, !domain_name || avahi_is_valid_domain_name(domain_name), AVAHI_ERR_INVALID_DOMAIN_NAME);
+
+ if (!domain_name) {
+ dn = avahi_strdup("local");
+ domain_name = dn;
+ }
+
+ if (avahi_domain_equal(s->domain_name, domain_name)) {
+ avahi_free(dn);
+ return avahi_server_set_errno(s, AVAHI_ERR_NO_CHANGE);
+ }