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Strip or preg_replace .zip, .exe, .rar, .rpm, .xz, etc. etc.

Discussion in 'PHP' started by qwikad.com, Jun 10, 2016.

0
  1. #1
    I'd like to have a strip function (or preg_replace) that strips all extensions that can be unzipped / installed. Searching the web didn't give me anything that would allow me to do that. Of course I can come up with something on my own, but I was wondering if a thing like that already exists.


     
    qwikad.com, Jun 10, 2016 IP
  2. Anveto

    Anveto Well-Known Member

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    #2
    There are so many extensions that can be extracted or installed that it seems kind of pointless to have a blacklist. You could simply strip any extension with 3 or 4 characters.

    preg_replace('/\\.[^.\\s]{3,4}$/','', $filename);
    PHP:
    Otherwise you might make an array of extensions you want to match and use rtrim.

    $filename = rtrim($filename, ".exe");
    PHP:
    But as I said, you are better off making a list of allowed extensions rather than trying to block every malicious extension. Whitelist is better than blacklist in this case.
     
    Anveto, Jun 10, 2016 IP
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  3. sarahk

    sarahk iTamer Staff

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    #3
    Can you give us a context of how it's going to be used?
    • to reject file uploads?
    • to list folder contents?
    I've done a thing in the past like this

    function checkFileExtension($name){
$blocked = array('zip','exe','rar','rpm'); // extend as necessary

$test = strrev($name);
$bits = explode('.',$test);
$ext = strrev($bits[0]);

return in_array($ext, $blocked);
}
    Code (markup):
    but you could also just do

    function checkFileExtension($name){
$blocked = array('zip','exe','rar','rpm'); // extend as necessary

$bits = explode('.',$name);
$ext = $bits[count($bits)-1];

return in_array($ext, $blocked);
}
    Code (markup):
    There will be a more elegant way but this is readable and easy to extend in the future.
     
    sarahk, Jun 10, 2016 IP
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  4. qwikad.com

    qwikad.com Illustrious Member Affiliate Manager

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    #4
    I ended up using something similar to what @sarahk has suggested. Realistically speaking there are only so many extensions out there, so I just included the commonly used ones into the array.
     
    qwikad.com, Jun 12, 2016 IP