Re: [PATCH xtables-nft v2] extensions: xt_socket: add txlate support for socket match

[Phil Sutter <phil@nwl.cc>]

On Wed, Mar 06, 2024 at 11:11:25AM +0100, Florian Westphal wrote:
> v2: document the match semantics of -m socket.
> 
> Ignore --nowildcard if used with other options when translating
> and add "wildcard 0" if the option is missing.
> 
> "-m socket" will ignore sockets bound to 0.0.0.0/:: by default,
> unless --nowildcard is given.
> 
> So, xlate must always append "wildcard 0", can elide "wildcard"
> if other options are present along with --nowildcard.
> 
> To emulate "-m socket --nowildcard", check for "wildcard <= 1" to
> get a "socket exists" type matching.
> 
> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
>  extensions/libxt_socket.c      | 39 ++++++++++++++++++++++++++++++++++
>  extensions/libxt_socket.txlate | 17 +++++++++++++++
>  2 files changed, 56 insertions(+)
>  create mode 100644 extensions/libxt_socket.txlate
> 
> diff --git a/extensions/libxt_socket.c b/extensions/libxt_socket.c
> index a99135cdfa0a..016ea3435339 100644
> --- a/extensions/libxt_socket.c
> +++ b/extensions/libxt_socket.c
> @@ -159,6 +159,42 @@ socket_mt_print_v3(const void *ip, const struct xt_entry_match *match,
>  	socket_mt_save_v3(ip, match);
>  }
>  
> +static int socket_mt_xlate(struct xt_xlate *xl, const struct xt_xlate_mt_params *params)
> +{
> +	const struct xt_socket_mtinfo3 *info = (const void *)params->match->data;
> +	const char *space = "";

The whole "leading space or not" handling is not necessary, I made
xt_xlate_add() insert leading space automatically if the first
character is alpha-numeric or a brace.

Thanks, Phil