[squid-users] Issue with header_access and validation

From: Paul-Kenji Cahier <pkc_at_F1-Photo.com>
Date: Fri, 2 May 2008 05:54:48 +0200

Hello,

In our current situation, we are trying to have "Cache-control: max-age=0" headers from clients to be ignored
in the cache decision process, while keeping all of the 'Cache-control: no-cache' and 'Pragma: no-cache'
still valid as making revalidation mandatory.

Without trying to do anything, when squid receives the max-age=0 directive, it decides to TCP_REFRESH_HIT since
the client asks it.

Our current approach was the following:
acl static_content req_header Cache-control max.age=0
header_access Cache-Control deny static_content

While the acl is properly matched, it seems the header_access does not ever get applied when deciding of what to do,
with the result that it's effectively being ignored.

Is there any way to make it be applied earlier/another way to ignore only 'Cache-control: max.age=0' headers?
(we would also preferably rather be able to define that with an acl so we can only apply that directive to
really probably static content)

The whole goal is to avoid firefox's F5/refresh button from forcing thousands of TCP_REFRESH_HIT/304 all the time,
which not only strains the servers but takes longer. Of course we also want users that want to force a refresh
(through ctrl+shift+R, which actually adds the no-cache directives) to be able to do so.(Caching is good,
but forcing delays before things are checked again is not)

Any suggestions will be really appreciated... We have tried to rewrite urls through privoxy, but it came messy
and fairly heavy on load, so a squid only solution would really be best.

-- 
Best regards,
 Paul-Kenji Cahier
mailto:pkc_at_F1-Photo.com
Received on Fri May 02 2008 - 03:54:55 MDT

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