Re: [libnftnl PATCH 3/7] set: Introduce NFTNL_SET_DESC_CONCAT_DATA

[Pablo Neira Ayuso <pablo@netfilter.org>]

Hi Phil,

On Wed, Nov 24, 2021 at 06:22:38PM +0100, Phil Sutter wrote:
> Analogous to NFTNL_SET_DESC_CONCAT, introduce a data structure
> describing individual data lengths of elements' concatenated data
> fields.
> 
> Signed-off-by: Phil Sutter <phil@nwl.cc>
> ---
>  include/libnftnl/set.h | 1 +
>  include/set.h          | 2 ++
>  src/set.c              | 8 ++++++++
>  3 files changed, 11 insertions(+)
> 
> diff --git a/include/libnftnl/set.h b/include/libnftnl/set.h
> index 1ffb6c415260d..958bbc9065f67 100644
> --- a/include/libnftnl/set.h
> +++ b/include/libnftnl/set.h
> @@ -33,6 +33,7 @@ enum nftnl_set_attr {
>  	NFTNL_SET_EXPR,
>  	NFTNL_SET_EXPRESSIONS,
>  	NFTNL_SET_DESC_BYTEORDER,
> +	NFTNL_SET_DESC_CONCAT_DATA,

This information is already encoded in NFTNL_SET_DATA_TYPE, the
datatypes that are defined in libnftables have an explicit byteorder
and length.

For concatenation, this information is stored in 6 bits (see
TYPE_BITS). By parsing the NFTNL_SET_DATA_TYPE field you can extract
both types (and byteorders) of the set definition.

For the typeof case, where a generic datatype such as integer is used,
this information is stored in the SET_USERDATA area.

This update for libnftnl is adding a third way to describe the
datatypes in the set, right?

>  	__NFTNL_SET_MAX
>  };
>  #define NFTNL_SET_MAX (__NFTNL_SET_MAX - 1)