CARP_NL_ADVSKEW
snl_add_msg_attr_s32(&nw, CARP_NL_ADVSKEW, carpr->carpr_advskew);
{ .type = CARP_NL_ADVSKEW, .off = _OUT(carpr_advskew), .cb = snl_attr_get_int32 },
{ .type = CARP_NL_ADVSKEW, .off = _OUT(advskew), .cb = nlattr_get_uint32 },
nlattr_add_s32(nw, CARP_NL_ADVSKEW, sc->sc_advskew);