Re: [SQU] Writing a script to view and download the contents of proxy cache?

Hi,

On Fri, 16 Feb 2001, Cameron Just wrote:

> Hi,
>
> I was wondering if it is possible to view and download the contents of
> a squid server via a web browser? I have checked the FAQs and could
> find any reference to it.
>
> I have since decided to write a script in php which will analyse the
> contents of theproxy cache and make it available via a webbrowser.
>
> I am using squid-2.3.STABLE1-5
> I first look at the contents of store.log and retrieve what I believe
> to be the contents of the cache at the moment. I then have a linkto
> another page which will dump the contents of the relavent file in the
> cache to the browser. The script will tell the browser what sort of
> file it is by sending the appropriate headers.
>
> Here is a line from store.log
> 982373047.567 SWAPOUT 0000001A 200 982327734 956284084 -1 image/gif 1020
> 2/10202 GET http://ads.msn.com/ads/HOTBOS/00338AH0014_LG.gif
>
> I have two problems at present.

> 1. Once I have the name of the file in the cache ie 0000001A How do I
> know where it is in the cache directory structure stored on the disk?
> The directory structure is quite deep and I can't quite see any strict
> pattern for locating the file

The name of the file actually includes the path to get there. That file
"0000001A" is actually "00/00/1A". Now, which cache is it in? Dunno cos
that file exists in every cache_dir.

>
> 2. Even downloading what I believe to be a GIF from the cache
> directory and renaming it to a .gif file. I cannot view it in anyimage
> viewer. Why? Is the file in some weird format?

Squid puts a header on all files in the cache. You need to remove it
before you get the "original" contents.

>
> So my main questions are
>
> Am I using the correct logfile?

Since you don't know which cache is in use at the time, I'd say not.

> How canI find out the exact location and filetype of a file stored in the cache?

You cannot, easily. Since squid is designed to find out quickly if a URL
is cached it uses two hashes. The first hashes the URL. This becomes the
key to a (hash) lookup in swap.state. The data returned is the filename
containing that URL.

The only surefire way to look at the cache is to scan it, reading the
headers in each file to determine what you are looking at.

Colin

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