Hello. I am running apache 2.2.15. I would like to use mod_cache, and I need a good way for SysAdmins to manually clear the cache for specific URLs when needed, but not allow users to do so from their browser.
It seems that when a browser sends headers Cache-Control: no-cache or Pragma: no-cache, mod_cache will go to the origin for the request and update the cache. That is a great way for SysAdmins to update the cache manually, but I want to protect the back-end application from malicious users (or just well-meaning users) doing a "shift-reload", which makes browsers send request headers like "max-age", "pragma", and/or "cache-control" and forcing mod_cache to bypass/update the cache. I tried using mod_headers and mod_setenvif to control the request headers. I ran into problems there. I could not get the directives: RequestHeader unset Pragma RequestHeader unset Cache-Control ...to work unless I specified "early" at the end of the directive. It seems that "early" is required in order for it to be processed before mod_cache gets the call. The problem, then, is that RequestHeader unset can have EITHER "early" or "env" in the option part of the directive. "env" was the portion I planned to use to limit stripping those request headers based on where they originate, like this: SetEnvIf Remote_Addr my\.ip\.address\.or\.LAN LOCALCALL RequestHeader unset Cache-Control env=!LOCALCALL RequestHeader unset Pragma env=!LOCALCALL I was hoping that would let me ONLY clear the cached object (manually and on-demand) from the local system or network, and prevent users (remote) from doing so via their browser request headers. I think the combination of "SetEnvIf" and "RequestHeader unset" may be a dead end for what I want to do (based on the exclusivity of "env" and "early"). If not, please advise. If that is a dead end, are there other ways to accomplish what I want to do? If I set "CacheIgnoreCacheControl On", is there a sane way to update a cached object based on it's URL (without scanning the cache directory structure, grepping header files for the URL and deleting the cache files, which I consider insane)? Is there a way to know the directory path to the cache files based on a given URL? Can I replicate that hashing algorithm to create the directory path and then "rm" the files? Or is that caching filename and path impossible to determine? Thanks, Anthony -- Anthony Dodson
