nl_set_nexthop_gw
error = nl_set_nexthop_gw(nh, attrs->nha_gw, attrs->nha_oif, npt);
int nl_set_nexthop_gw(struct nhop_object *nh, struct sockaddr *gw,
error = nl_set_nexthop_gw(nh, mpnh->gw, mpnh->ifp, npt);
*perror = nl_set_nexthop_gw(nh, attrs->rta_gw, attrs->rta_oif, npt);