Re: [PATCH] entry_data

[Patrick McHardy <kaber@trash.net>]

Sven Anders wrote:
> Massimiliano Hofer schrieb:
> 
>>Hi,
>>here is my proposed patch for an API change that supports entry specific data.
>>
>>As explained in my previous posts the purpose of this patch is to give matches 
>>the opportunity to store entry specific data. Several matches already achieve 
>>this reserving some space in the data fields, but these come from userspace 
>>and I don't think it is the Right Way(TM) to do it.
> 
> 
> Does this mean we can reuse these fields for other puroposes without breaking
> compatibility with iptables?

Yes, userspace ignores these fields. I still haven't really made up my
mind about this patch yet. I don't like the void ** approach very much,
but I didn't got around to thinking about something better yet. Please
stay patient with me :)

> I'm particularly interested in adding a negation to the "limit" match and I
> think the match is using one of these special data fields...
> 
>  > /* Ugly, ugly fucker. */
>  >  struct xt_rateinfo *master;
> 
> If this gives us the possibility to add the negation, who do we distinguish
> between the old and new limit version. In other words: Who do we reach a maximum
> compatibility?

IIRC userspace zeroes this field, so you could just do the usual
"0 -> no inversion, 1 -> inversion" thing and it would behave
correctly for both old and new userspace. But you need check
yourself if this is indeed true, I'm not really sure.