PF_RUT_UID_LOW
snl_add_msg_attr_u32(nw, PF_RUT_UID_LOW, uid->uid[0]);
{ .type = PF_RUT_UID_LOW, .off = _OUT(uid[0]), .cb = snl_attr_get_uint32 },
{ .type = PF_RUT_UID_LOW, .off = _OUT(uid[0]), .cb = nlattr_get_uint32 },
nlattr_add_u32(nw, PF_RUT_UID_LOW, u->uid[0]);