Re: Comparing strings... need advice. :)

On Mon, 2006-08-28 at 16:50 +0200, Ivo F.A.C. Fokkema wrote: > On Mon, 28 Aug 2006 09:47:02 +0100, Stut wrote: > > > Micky Hulse wrote: > >> I am looking for the most secure/efficient way to compare these two > >> strings: > >> > >> /folder1/folder2/folder3/folder4/ > >> /folder1/folder2/folder3/folder4/file.php > >> > >> Basically I am trying to setup as many security features as possible for > >> a simplistic (home-grown/hand-coded) CMS... > >> > >> This appears to work: > >> > >> $haystack = '/folder1/folder2/folder3/folder4/someFileName.php'; > >> $needle = '/folder1/folder2/folder3/folder4/'; > >> if(substr_count($haystack, $needle) === 1) echo "yea"; > >> > >> Before making changes to "someFileName.php" I want to make sure it is > >> within the allowed path ($needle). > > > > First of all make sure you are sending both strings through realpath > > (http://php.net/realpath) to remove any symbolic links and relative > > references. Then you can compare the two strings. The way you're doing > > it will work but it's probably not very efficient. This is what I use... > > > > $valid = (strcmp($needle, substr($haystack, 0, strlen($needle))) == 0); > > > > Personally, this seems simpler to me: > > $valid = (dirname($haystack) == $needle); > > But the way the above folders are presented, it should become > > $valid = (dirname($haystack) == rtrim($needle, '/')); > > less simple already... Possibly, this is not the best solution for some > reason I don't know. If so, I would like to know :) The above technique doesn't allow for sub-directories. It only allows for files within the needle directory. Cheers, Rob. -- .------------------------------------------------------------. | InterJinn Application Framework - http://www.interjinn.com | :------------------------------------------------------------: | An application and templating framework for PHP. Boasting | | a powerful, scalable system for accessing system services | | such as forms, properties, sessions, and caches. InterJinn | | also provides an extremely flexible architecture for | | creating re-usable components quickly and easily. | `------------------------------------------------------------'