is_hexadecimal recognizes non hex-strings as hexadecimal

[DkSoul]

Hello,

I'm having problems with the output values returned by some scripts because cacti is interpreting them as hexadecimal values.

Example:

is_hex.php

Code: Select all

<?php
function is_hexadecimal($hexstr) {
        $hexstr = trim($hexstr);
        $i      = 0;
        $length = strlen($hexstr);
        while ($i < $length) {
                $part = substr($hexstr,$i,2);
                $i += 2;

                if (!preg_match('/[a-fA-F0-9]/', $part)) {
                        return false;
                } elseif ($i < $length) {
                        if (substr($hexstr,$i,1) != ":") {
                                return false;
                        }elseif ($i + 1 == $length) {
                                return false;
                        }
                        $i++;
                }else{
                        $i++;
                }
        }

        return true;
}
if ( is_hexadecimal($_SERVER["argv"][1]) ) {
  echo "Is hexadecimal!\n";
} else {
  echo "Not hexadecimal!\n";
}
?>

Code: Select all

$ php is_hex.php "jc:1"
Is hexadecimal!

Code: Select all

$ php is_hex.php "zf:5y:2"
Is hexadecimal!

I would like to know what are/should be the rules for an hex-string so that I can either rewrite this function or change the scripts.

Thank you!

PS: The function is_hexadecimal is inside cacti/site/lib/functions.php
PS2: Fixed this by replacing the regex with ^[a-fA-F0-9]{2}$. I would still like to know if this is really a bug or if by changing this I'm messing with something else..

[gandalf]

Good find. Current code is obviously broken. Personally, I do prefer a different solution. But I will have to test that performance-wise.
R.

[DkSoul]

Good find. Current code is obviously broken. Personally, I do prefer a different solution. But I will have to test that performance-wise.
R.

So far I've not seen any side effects from changing the regex, so I'm going to leave it like that.
Thank you for your feedback gandalf!