RTA_NEXT
for (; RTA_OK(rt_attr, rtl); rt_attr = RTA_NEXT(rt_attr, rtl)) {
for (; RTA_OK(rt_attr, rtl); rt_attr = RTA_NEXT(rt_attr, rtl)) {
for (; RTA_OK(attr, len); attr = RTA_NEXT(attr, len)) {
rta = RTA_NEXT(rta, len);
attrs = RTA_NEXT(attrs, len);
attrs = RTA_NEXT(attrs, len);
attrs = RTA_NEXT(attrs, len);
attrs = RTA_NEXT(attrs, msg_len);
grp = RTA_NEXT(grp, grp_len);
grps = RTA_NEXT(grps, grps_len);
attrs = RTA_NEXT(attrs, len);
attrs = RTA_NEXT(attrs, len);