Re: [squid-users] Issue with header_access and validation

Use refresh_pattern entries to override the max-age.

On Fri, May 02, 2008, Paul-Kenji Cahier wrote:
> 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@F1-Photo.com

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