Re: ACL convention for content filtering?

From: Henrik Nordstrom <hno@dont-contact.us>
Date: Tue, 30 Jan 2001 02:10:38 +0100

I think you need to define a new "acl" concept for this to work. The
current "acl" concept is only designed for true/false evaulations, not
active rewrites.

The ACL scheme can be used for screening what to apply the filters to,
but not the actual data munging.

normal "access" rule:

acl myregexfilter filter_word_regex naughtyword
filter bleep replace bleep
filter_access bleep allow myregexfilter

"acl" based filter rules, like deny_info:

acl myregexfilter filter_word_regex naughtyword
filter bleep replace bleep
filter_content deny myregexfilter
filter_match myregexfilter bleep

I'd probably prefer the last approach (filter_content). It can be set up
to require less computing power (especially if there is many filters),
but is unfortunately a bit harder to configure..

Anyway, the main issue here (config syntax) is that ACL processing
should use lists of acl's to allow short-circuits for common content
which should not be filtered.

/Henrik

Joe Cooper wrote:
>
> Hey folks,
>
> Moez and I (mostly Moez! ;-) have been discussing implementation of
> content filtering via ACL, specifically, HTML tag based filtering. I
> think Moez is actually beginning the final steps to get this into an
> ACL. And here's what we're thinking about doing for modifying tags in HTML:
>
> acl myurlfilter filter_href www.foo.com
>
> With the other part of the feature being:
>
> filter myurlfilter rewrite www.bar.com
>
> Obviously the goal is to continue to evolve it to be more generic, and
> include all of the various tag types (for example, the ability to strip
> javascript, gif anim bits, etc.). But for the time being, the
> functionality I need is the ability to modify a URL inline.
>
> I welcome further comments, because I'm a little vague on how best to
> present this kind of functionality in a generic way that still makes
> sense to a human. The above really only works for a very few types of
> modification...but it does work for the very generic "filter_regex"
> type, which is nice. I.e.:
>
> acl myregexfilter filter_regex naughtyword
>
> filter myregexfilter rewrite bleep
>
> To bleep out naughtywords...
>
> or
>
> filter myregexfilter deny
>
> To simply erase them...
>
> or
>
> filter myregexfilter highlight
>
> To highlight them, ala the Deja or Google search (when viewing the
> cached version which highlights the query terms).
>
> etc.... Just some thoughts.
>
> Robert, in particular, I imagine you must have done some thinking on
> this very subject. How do you want to see your filters come into being
> an ACL?
>
> Thanks.
> --
> Joe Cooper <joe@swelltech.com>
> Affordable Web Caching Proxy Appliances
> http://www.swelltech.com
Received on Mon Jan 29 2001 - 18:18:18 MST

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