Re: [rfc] using xor in mark targets

[Patrick McHardy <kaber@trash.net>]

Jan Engelhardt wrote:
> On Dec 4 2007 09:11, Patrick McHardy wrote:
>>> But it concerns CONNMARK. See this patch, which introduces --set-xmark.
>>>
>>> Assumes a xt_CONNMARK.ko v2 that does:
>>> --set:
>>> 	ctmark = (ctmark & info->ctmark_mask) ^ info->ctmark_value;
>>> --save:
>>> 	ctmark = (nfmark & info->nfmark_mask) ^ (ctmark & info->ctmark_mask);
>>> --restore:
>>>  nfmark = (nfmark & info->nfmark_mask) ^ (ctmark & info->ctmark_mask);
>>>
>>> As you can see, it would introduce a new option "--set-xmark", and
>>> that name does not sound as appalling as --set-mark, so I was looking
>>> for a better one ;-)
>> It would be easier for me if you'd explain what every option does,
>> especially why you need this set-xmark option.
>>
> --set-xmark would use the (yet to be written) xt_CONNMARK v2 semantic,
> while --set-mark would do the compatible v0/v1 one.
> 
> What xt_CONNMARK does at the moment (.revision=0/1):
> 	ctmark = (ctmark & info->mask) | info->mark;
> 
> Essential operation of xt_CONNMARK (.revision=2):
>>> 	ctmark = (ctmark & info->ctmark_mask) ^ info->ctmark_value;
> 
> For CONNMARK, this allows to and/or/xor bits in one go rather than just
> selectively and/or, as it is now.


I still don't see why you can't keep --set-mark and add new options
--and-mark, --xor-mark, ...