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

On Mon, 28 Aug 2006 19:39:49 -0400, Robert Cummings wrote: > 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. Ah, thanks. Misunderstood the question, then. Thought just checking if it's a file in that directory was what's needed.