Image Leeching / Random querystring fix?

Check out example on using CACHE::uri if you are using 9.2 or later release. This rule sets the effective URI without modifying it on the wire.

 

 

You could definitely check to see if the URI requested contains the string ".jpg" and then check the "Referer" (sic) header and check to see if it comes from your sites. I don't have time to write it for you, but it should be pretty straightforward to do this sort of rule.

There is a related example in the codeshare for restricting access to specific file types using the referer header.

 

 

Click here

 

 

Aaron

Hi All,

 

 

Thank you for the responses. I'm going to try an example of the CacheBusterBuster in hopes that you can help fill in the blanks.

 

 

We have requests that come in for static content such as these:

 

http://site.com/image/image.jpg?12313

 

http://site.com/image/image.jpg?random=12313

 

http://site.com/swf/mysef.swf?r=6644

 

 

I'd like to be able to just return the object that is already in cache - here is a starting point:

 

 

iRule = CacheBusterBuster

 

 

when CACHE_REQUEST {

 

if { [string tolower [HTTP::uri]] contains "?" } {

 

CACHE::Uri [string first {?} [HTTP::uri] 0]

 

}

 

}

 

 

Please let me know if this will work or if there is a better way to do this?

 

Thanks!

'[string first {?} $myUri 0]' will return an index of the first occurrence of the ? character. You could use that index in string range to get all characters up to that index:

 

 

[string range [HTTP::uri] 0 [expr [string first {?} [HTTP::uri] 0] - 1]

 

 

Or you could just use HTTP::path to get the path and object (/image/image.jpg for example) without the query string.

 

 

Aaron

Thanks Aaron - so would this work:

 

 

iRule = CacheBusterBuster

 

 

when CACHE_REQUEST {

 

CACHE::Uri [HTTP::host][HTTP::path]

 

}

 

 

Does setting CACHE::Uri tell the CACHE to send back this file instead of [HTTP::Uri]?

 

I haven't used the CACHE:: functions before as I haven't had a license for it, and I couldn't find any example rules that used CACHE::uri so I'm not very clear on the commands. But based on Bl0ndie's post (Click here), I don't think any change is made to the actual request. The change is just to what the caching module logically parses the request as.

 

 

 

This forces the [caching module] to store the documents under the different URI without actually changing the URI on the wire. This logic should be employed in HTTP_REQUEST event.

 

 

 

 

So per this and the wiki page, you should change the event from CACHE_REQUEST to HTTP_REQUEST.

 

 

 

http://devcentral.f5.com/wiki/default.aspx/iRules/CACHE__uri.html

 

 

CACHE::uri

 

 

* Overrides the URI value used by the cache to store the cached content, according to the specified string.

 

 

 

 

Maybe someone that has used the caching commands could elaborate?

 

 

Thanks,

 

Aaron

I've tried to update it as follows, but I'm still seeing the cache build up on requests:

 

 

when HTTP_REQUEST {

 

set CACHE::Uri [HTTP::host][HTTP::path]

 

}

When I do that, I get the following error:

 

 

01070151:3: Rule [CacheBusterBuster] error:

 

line 2: [undefined procedure: CACHE::uri] [CACHE::uri [HTTP::host][HTTP::path]]

Are you on 9.2 or higher? It looks like the CACHE::uri command was added in 9.2.0.

I tried testing the following rule, but got an error because I don't have a unit licensed for the caching module.

when HTTP_REQUEST {
   if {[HTTP::uri] contains "?"}{
      CACHE::uri [HTTP::host][HTTP::path]
   }
}

The command is recognized, but not licensed. If I change it to CACHE:Uri, I get an unrecognized command error.

Aaron