int sd_rtnl_message_append_in6_addr(sd_rtnl_message *m, unsigned short type, const struct in6_addr *data);
int sd_rtnl_message_append_ether_addr(sd_rtnl_message *m, unsigned short type, const struct ether_addr *data);
-int sd_rtnl_message_open_container(sd_rtnl_message *m, unsigned short type);
+int sd_rtnl_message_open_container(sd_rtnl_message *m, unsigned short type, size_t extra);
int sd_rtnl_message_close_container(sd_rtnl_message *m);
int sd_rtnl_message_read(sd_rtnl_message *m, unsigned short *type, void **data);