PHP - Shorter Magic Quotes Solution

Question

I'm writing a app that needs to be portable. I know I should disable magic quotes on the PHP configuration but in this case I don't know if I can do that, so I'm using the following code:

if (get_magic_quotes_gpc() === 1)
{
    $process = array(&$_GET, &$_POST, &$_COOKIE, &$_REQUEST);

    while (list($key, $val) = each($process))
    {
        foreach ($val as $k => $v)
        {
            unset($process[$key][$k]);

            if (is_array($v))
            {
                $process[$key][stripslashes($k)] = $v;
                $process[] = &$process[$key][stripslashes($k)];
            }

            else
            {
                $process[$key][stripslashes($k)] = stripslashes($v);
            }
        }
    }

    unset($process);
}

To simplify the process of disabling magic quotes I had the following idea:

if (get_magic_quotes_gpc() === 1)
{
    foreach (array('GET', 'POST', 'COOKIE', 'REQUEST') as $array)
    {
        ${'_'.$array} = unserialize(stripslashes(serialize(${'_'.$array})));
    }
}

But I tried and I got an error I'm unable to understand, for instance with ?name=O'Reilly:

serialize($_GET); // a:1:{s:4:"name";s:9:"O\'Reilly";}
stripslashes(serialize($_GET)); // a:1:{s:4:"name";s:9:"O'Reilly";}

But unserialize(stripslashes(serialize($_GET))) gives me this weird error:

Notice: unserialize(): Error at offset 30 of 32 bytes

---

EDIT: Due to the length attribute in serialize() I changed the code to use JSON functions:

if (get_magic_quotes_gpc() === 1)
{
    foreach (array('GET', 'POST', 'COOKIE', 'REQUEST') as $array)
    {
        ${'_' . $array} = json_decode(stripslashes(json_encode(${'_' . $array})), true);
    }
}

However now the $_GET array is coming up empty, can anyone explain me why?

Answer 1

I don't think the second version will work. Serialized strings are stored along with their length, if you are removing characters, you would need to update that length value. I would rather implement it this way to improve readability:

function strip_slashes_recursive(&$value) {
    if (!is_array($value)) {
        $value = strip_slashes($value);
    } else {
        foreach (array_keys($value) as $key) {
            $arrayValue = strip_slashes_recursive($value[$key]);
            unset($value[$key]);
            $value[strip_slashes($key)] = $arrayValue;
        }
    }
}

foreach (array(&$_GET, &$_POST, &$_COOKIE, &$_REQUEST) as &$array) {
    strip_slashes_recursive($array);
}
// don't forget to unset references or it can lead to very nasty bugs
unset($array);

Answer 2

I usually solve that problem this way:

function smagic($params){
    if(get_magic_quotes_gpc()){
        if(!is_array($params))
            return stripslashes($params);
        else
            return array_combine( array_map('stripslashes',array_keys($params)), array_map('smagic',array_values($params)) );
    }
}

And then, for $_GET:

$_GET = smagic($_GET);

Answer 3

Solved it, I had to use the JSON_HEX_APOS flag in json_encode():

if (get_magic_quotes_gpc() === 1)
{
    $_GET = json_decode(stripslashes(json_encode($_GET, JSON_HEX_APOS)), true);
}

---

Before (mqgpc.php?name[got'cha]=O'Reilly):

Array
(
    [name] => Array
        (
            [got\'cha] => O\'Reilly
        )
)

After (mqgpc.php?name[got'cha]=O'Reilly):

Array
(
    [name] => Array
        (
            [got'cha] => O'Reilly
        )
)