PF_TO_SECONDS
snl_add_msg_attr_u32(&nw, PF_TO_SECONDS, seconds);
{ .type = PF_TO_SECONDS, .off = _OUT(seconds), .cb = snl_attr_get_uint32 },
{ .type = PF_TO_SECONDS, .off = _OUT(seconds), .cb = nlattr_get_uint32 },
nlattr_add_u32(nw, PF_TO_SECONDS, attrs.seconds);