mysql_real_escape_string() for entire $_REQUEST array, or need to loop through it?

Question

Is there an easier way of safely extracting submitted variables other than the following?

if(isset($_REQUEST['kkld'])) $kkld=mysql_real_escape_string($_REQUEST['kkld']);
if(isset($_REQUEST['info'])) $info=mysql_real_escape_string($_REQUEST['info']);
if(isset($_REQUEST['freq'])) $freq=mysql_real_escape_string($_REQUEST['freq']);

(And: would you use isset() in this context?)

Answer 1

To escape all variables in one go:

$escapedGet = array_map('mysql_real_escape_string', $_GET);

To extract all variables into the current namespace (i.e. $foo = $_GET['foo']):

extract($escapedGet);

Please do not do this last step though. There's no need to, just leave the values in an array. Extracting variables can lead to name clashes and overwriting of existing variables, which is not only a hassle and a source of bugs but also a security risk. Also, as @BoltClock says, stick to $_GET or $_POST. Also2, as @zerkms points out, there's no point in mysql_real_escaping variables that are not supposed to be used in a database query, it may even lead to further problems.

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Note that really none of this is a particularly good idea at all, you're just reincarnating magic_quotes and global_vars, which were horrible PHP practices from ages past. Use prepared statements with bound parameters via mysqli or PDO and use values through $_GET or filter_input. See http://www.phptherightway.com.

Answer 2

You can also use a recursive function like this to accomplish that

function sanitate($array) {
   foreach($array as $key=>$value) {
      if(is_array($value)) { sanitate($value); }
      else { $array[$key] = mysql_real_escape_string($value); }
   }
   return $array;
}
sanitate($_POST);

Answer 3

As far as I'm concerned Starx' and Ryan's answer from Nov 19 '10 is the best solution here as I just needed this, too.

When you have multiple input fields with one name (e.g. names[]), meaning they will be saved into an array within the $_POST-array, you have to use a recursive function, as mysql_real_escape_string does not work for arrays.

So this is the only solution to escape such a $_POST variable.

function sanitate($array) {
    foreach($array as $key=>$value) {
        if(is_array($value)) { sanitate($value); }
            else { $array[$key] = mysql_real_escape_string($value); }
   }
   return $array;
}
sanitate($_POST);

Answer 4

To sanitize or validate any INPUT_GET, INPUT_POST, INPUT_COOKIE, INPUT_SERVER, or INPUT_ENV, you can use

• filter_input_array — Gets external variables and optionally filters them

Filtering can be done with a callback, so you could supply mysql_real_escape_string.

This method does not allow filtering for $_REQUEST, because you should not work with $_REQUEST when the data is available in any of the other superglobals. It's potentially insecure.

The method also requires you to name the input keys, so it's not a generic batch filtering. If you want generic batch filtering, use array_map or array_walk or array_filter as shown elsewhere on this page.

Also, why are you using the old mysql extension instead of the mysqli (i for improved) extension. The mysqli extension will give you support for transactions, multiqueries and prepared statements (which eliminates the need for escaping) All features that can make your DB code much more reliable and secure.

Answer 5

If you use mysqli extension and you like to escape all GET variables:

$escaped_get = array_map(array($mysqli, 'real_escape_string'), $_GET);

Answer 6

As an alternative, I can advise you to use PHP7 input filters, which provides a shortcut to sql escaping. I'd not recommend it per se, but it spares creating localized variables:

 $_REQUEST->sql['kkld']

Which can be used inline in SQL query strings, and give an extra warning should you forget it:

 mysql_query("SELECT x FROM y WHERE z = '{$_REQUEST->sql['kkld']}'");

It's syntactically questionable, but allows you escaping only those variables that really need it. Or to emulate what you asked for, use $_REQUEST->sql->always();