Little Impact

I recently had a problem with my website zimmer69.de. Some not so nice fellow told his opera browser to reload a 300k page every 5 seconds, moved it to some tab and forgot about it for weeks. He caused 2 Gb of traffic per day. Time to implement some cache control.
Continue reading 'Auto reload and poor man's http caching in PHP' »

I recently found a shell injection bug in some Ruby-gem I use.

Shell injections have scared me for a long time and I usually prefer to whitelist certain characters/patterns rather than to blacklist. This means that the system fails to the save side. Unfortunally it usually does fail – my whitelisting is to rigorous and data that would not cause any problems gets rejected. So I decided to take the opportunity to investigate how to prevent shell injection in my favorite scripting language (Python), the language I found the problem in and finally the language that I can not avoid (PHP).

Continue reading 'Avoiding Shell Injection in Ruby, Python and PHP.' »

I tweaked the robots-meta plugin by Joost de Valk for WordPress to support the noarchive tag. This prevents google and archive.org from providing cached versions of your blog.

I've put up a mercurial repo with my version at http://www.littleimpact.de/hg/robots-meta-hg/.