Re: [squid-users] Compute digest as content is written to cache

From: Jack Bates <>
Date: Sat, 11 Aug 2012 03:21:34 -0700

On 11/08/12 12:30 AM, Amos Jeffries wrote:
> On 11/08/2012 7:22 p.m., Jack Bates wrote:
>> I am interested in intercepting content as it is written to the cache,
>> and computing a digest from the content. Do you know if this can be
>> done in some kind of add on, or would it require a change to the core?
> What type of digest and to what purpose?

I was thinking of using OpenSSL
SHA256_Init()/SHA256_Update()/SHA256_Final(). The purpose I have in mind
is to detect identical content at different URLs

Given a response with a "Location: ..." header and a "Digest:
SHA-256=..." header (such as from MirrorBrain), if the URL in the
"Location: ..." header is not already cached but the "Digest:
SHA-256=..." header matches the content at some other URL that is
already cached, then I want to update the "Location: ..." header with
the cached URL. I think this should redirect clients to mirrors that are
already cached
Received on Sat Aug 11 2012 - 10:22:08 MDT

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