typedef int (*sd_rtnl_message_handler_t)(sd_rtnl *rtnl, sd_rtnl_message *m, void *userdata);
/* bus */
-int sd_rtnl_open(sd_rtnl **nl, uint32_t groups);
+int sd_rtnl_open(sd_rtnl **nl, unsigned n_groups, ...);
sd_rtnl *sd_rtnl_ref(sd_rtnl *nl);
sd_rtnl *sd_rtnl_unref(sd_rtnl *nl);