Re: content filtering : programming advice needed

From: Jonathan Larmour <>
Date: Mon, 16 Jun 1997 14:24:29 +0100

At 12:37 14/06/97 +0100, Magossa'nyi A'rpa'd wrote:
>I want squid to enable flexible content filtering. I thought of some
>possibility to call external filter program on retrieving a page, before
>writing it to the cache or giving away to clients. I know you've talked on
>it some times, and the consensus was that it is too computational intensive.
[snip various suggestions for modifying code]

This is not really something Squid could easily do flexibly, well (due to
the event model - unless it was passed to a different process, which is
what I'm about to suggest below anyway), and as you say, computationally

If you want to do filtering, run a separate content-filtering proxy such as
the FWTK's http-gw 2.0, on the same machine, and make it a parent of squid
(and turn single_parent_bypass on). This way you can cache the filtered pages.

The thing you lose is the advantage of being in a cache hierarchy - but you
can still be the "top" of a hierarchy yourself. If this is a big issue, you
could swap it around, and hack the http-gw to use squid as a "parent", and
make users use the http-gw first. But then you will be filtering each
object every time it is requested, rather than it just being returned from
the cache.

One of these is likely to be the way forward for you.

Jonathan L.

Origin UK,323 Cambridge Science Park,Cambridge,England. Tel: +44(1223)423355
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Received on Mon Jun 16 1997 - 06:41:03 MDT

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