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From Nick Kew <n...@webthing.com>
Subject Re: [PATCH] mod_deflate + mod_proxy bug
Date Thu, 10 Jun 2004 08:28:46 GMT
On Wed, 9 Jun 2004, Allan Edwards wrote:

> Running ProxyPass with mod_deflate results in
> an extraneous 20 bytes being tacked onto 304
> responses from the backend.
>
> The problem is that mod_deflate doesn't handle
> the zero byte body, adds the gzip header and
> tries to compress 0 bytes.
>
> This patch detects the fact that there was no
> data to compress and removes the gzip header
> from the bucket brigade.
>
> Any comments before I commit to head?

This is part of a slightly broader problem with proxying and mod_deflate:
it'll also waste time gzipping already-compressed data from the backend
in those cases where the compression is not explicitly indicated in the
Content-Encoding header.  Obvious examples are all the main image formats.

I'm currently running a hack that works around this, and planning a
better review when time permits (i.e. when I've caught up with things
after http://www.theatreroyal.com/showpage.php?dd=1&theid=2578
which now has three nights left to run).

More interesting is the entire subject of filtering in a dynamic
context such as a proxy.  The directives available to control filtering
are simply not up to it.  Watch this space:-)

-- 
Nick Kew

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