CapÃtulo 31. Comillas MÃ¡gicas

Tabla de contenidos
QuÃ© Son Las Comillas MÃ¡gicas
PorquÃ© Usar Comillas MÃ¡gicas
PorquÃ© No Usar Comillas MÃ¡gicas
DesactivaciÃ³n de Comillas MÃ¡gicas

Las comillas mÃ¡gicas (o "Magic Quotes") se refieren a un proceso que automÃ¡ticamente escapa datos de entrada en los scripts de PHP. Es recomendable escribir cÃ³digo con las comillas mÃ¡gicas deshabilitadas, y en su lugar escapar los datos en tiempo de ejecuciÃ³n, a medida que se necesite.

QuÃ© Son Las Comillas MÃ¡gicas

Cuando se habilitan, todos los caracteres ' (comilla sencilla), " (comilla doble), \ (barra invertida) y NULL se escapan con una barra invertida de forma automÃ¡tica. Esto es idÃ©ntico a lo que hace addslashes().

Existen tres directivas de comillas mÃ¡gicas:

magic_quotes_gpc
Afecta los datos de peticiones HTTP (GET, POST y COOKIE). No puede definirse en tiempo de ejecuciÃ³n, y su valor predeterminado es on en PHP.
Vea tambiÃ©n get_magic_quotes_gpc().
magic_quotes_runtime
Si se habilita, la mayorÃa de funciones que devuelven datos de una fuente externa, incluyendo bases de datos y archivos de texto, escaparÃ¡n las comillas con una barra invertida. Puede definirse en tiempo de ejecuciÃ³n, y su valor predeterminado en PHP es off.
Vea tambiÃ©n set_magic_quotes_runtime() y get_magic_quotes_runtime().
magic_quotes_sybase
Si se habilita, una comilla sencilla se escapa con una comilla sencilla en lugar de una barra invertida. Asimismo, sobreescribe completamente magic_quotes_gpc. Habilitar ambas directivas quiere decir que sÃ³lo las comillas sencillas se escapan como ''. Las comillas dobles, las barras invertidas y los NULL permanecerÃ¡n intactos y sin escapar.
Vea tambiÃ©n ini_get() para conocer su valor.

add a note User Contributed Notes
Comillas MÃ¡gicas

judas dot iscariote at gmail dot com
07-Mar-2006 11:33


Just for the record. this feature has been removed as of PHP6.

now PHP works always like if magic_quotes_gpc Off.



get_magic_quotes_gpc, get_magic_quotes_runtime are kept but always return false, set_magic_quotes_runtime raises an E_CORE_ERROR.



this is great news, magic_quotes were a big annoyance.

27-Feb-2006 03:11


Using the .htaccess file may not always be possible for instance if you are running php on a windows IIS server.



Also the code by jfrim at idirect dot com doesn't actually fix the problem as it is stripping slashes, what you need to do is addslashes to things coming in.



the code by jfrim at idirect dot com is the right idea though although rather than saying stripslashes, you simply need to say addslashes and it should work.

edward at example dot com
07-Feb-2006 04:55


All the code listed on this page is not necessary if you use the php_flag directive in a .htaccess file. This allows you to disable magic quotes completely, without the need to adjust your php.ini file or (re)process the user's input.



Just take a look at http://www.php.net/manual/en/http://indices.com.es/security.magicquotes.html#55935



Gist of his note: in the .htaccess file, add a line



php_flag magic_quotes_gpc off



That's it. Thank you very much, richard dot spindler :) !

jfrim at idirect dot com
27-Jan-2006 10:31


Unfortunately magic_quotes_gpc can not be changed at run-time, but here's a code block which will effectively get rid of it when executed.  Use this for PHP scripts which must be portable or run on servers where magic_quotes_gpc could be configured either way.



Note that the PHP help is a little misleading...  Magic_quotes_gpc affects more than just the Get, Post, and Cookie data!



<?php

//Prevent Magic Quotes from affecting scripts, regardless of server settings



//Make sure when reading file data,

//PHP doesn't "magically" mangle backslashes!

set_magic_quotes_runtime(FALSE);



if (get_magic_quotes_gpc()) {

    /*

    All these global variables are slash-encoded by default,

    because    magic_quotes_gpc is set by default!

    (And magic_quotes_gpc affects more than just $_GET, $_POST, and $_COOKIE)

    */

    $_SERVER = stripslashes_array($_SERVER);

    $_GET = stripslashes_array($_GET);

    $_POST = stripslashes_array($_POST);

    $_COOKIE = stripslashes_array($_COOKIE);

    $_FILES = stripslashes_array($_FILES);

    $_ENV = stripslashes_array($_ENV);

    $_REQUEST = stripslashes_array($_REQUEST);

    $HTTP_SERVER_VARS = stripslashes_array($HTTP_SERVER_VARS);

    $HTTP_GET_VARS = stripslashes_array($HTTP_GET_VARS);

    $HTTP_POST_VARS = stripslashes_array($HTTP_POST_VARS);

    $HTTP_COOKIE_VARS = stripslashes_array($HTTP_COOKIE_VARS);

    $HTTP_POST_FILES = stripslashes_array($HTTP_POST_FILES);

    $HTTP_ENV_VARS = stripslashes_array($HTTP_ENV_VARS);

    if (isset($_SESSION)) {    #These are unconfirmed (?)

        $_SESSION = stripslashes_array($_SESSION, '');

        $HTTP_SESSION_VARS = stripslashes_array($HTTP_SESSION_VARS, '');

    }

    /*

    The $GLOBALS array is also slash-encoded, but when all the above are

    changed, $GLOBALS is updated to reflect those changes.  (Therefore

    $GLOBALS should never be modified directly).  $GLOBALS also contains

    infinite recursion, so it's dangerous...

    */

}



function stripslashes_array($data) {

    if (is_array($data)){

        foreach ($data as $key => $value){

            $data[$key] = stripslashes_array($value);

        }

        return $data;

    }else{

        return stripslashes($data);

    }

}

?>

06-Dec-2005 06:09


You should try to avoid magic_quotes in all its flavors, use add_slashes() and strip_slashes() instead with user input and you will save time and avoid common problems that come along.



You should know also that if your server has php suexec enabled you won't be able use php_flag in .htaccess file to change php values like magic_quotes or register_globals. In this case you might wanna try creating a php.ini file on the same directory as your script and add something like this:



magic_quotes_runtime=off

magic_quotes_gpc=off

magic_quotes_sybase=off

register_globals=on ; only as an example



----

Mel

http://www.webhostingjournal.net/

richard dot spindler at gmail dot com
18-Aug-2005 01:59


to turn of magic quotes put the following line into the .htaccess file:



php_flag magic_quotes_gpc off

16-Jul-2005 07:44


Bright minds will have noticed, that one uses stripslashes() once on the input and saves that content for further processing. Then use addslashes() once before sending the content to the database or flat file.



Hint: if the application is using a MySql database, don't use addslashes() but mysql_real_escape_string().

nitrous at fuckoff dot com
26-Jan-2005 11:01


This "feature" is the cause of so many escaping problems.  It's very important to understand the implications of what magic quotes really do.



Nearly every call, except those being written directly to the database, using user submitted data will require a call to strip_slashes.  It gets very ugly very fast.



What should be done is proper escaping of shell parameters and database parameters. PHP provides several escaping functions intended for this purpose. Slashes alone don't cut it anyway.

add a note