mysql_query
To answer the previous comment.
You are not supposed to send the sql sentence to the function, but only for user provided parameters of the sql sentence to be sure that user can't inject sql code.
Say, you ask that menu-attribute of your example from user, it would become:
$attr=$_POST['attr'];
$sql="Select * from table where attribute = '" . mysql_real_escape_string($attr) . "'"';
mysql_real_escape_string
(PHP 4 >= 4.3.0, PHP 5)
mysql_real_escape_string — Protège les caractères spéciaux d'une commande SQL
Description
string mysql_real_escape_string
( string $unescaped_string
[, resource $link_identifier
] )
mysql_real_escape_string() protège les caractères spéciaux de la chaîne unescaped_string, en prenant en compte le jeu de caractères courant de la connexion link_identifier. Le résultat peut être utilisé sans problème avec la fonction mysql_query(). Si des données binaires doivent être insérées, cette fonction doit être utilisée.
mysql_real_escape_string() appelle la fonction mysql_escape_string() de la bibliothèque MySQL qui ajoute un anti-slash aux caractères suivants : NULL, \x00, \n, \r, \, ', " et \x1a.
Cette fonction doit toujours (avec quelques exceptions) être utilisée pour protéger vos données avant d'envoyer la requête à MySQL.
Liste de paramètres
- unescaped_string
-
La chaîne à échapper.
- link_identifier
-
La connexion MySQL. S'il n'est pas spécifié, la dernière connexion ouverte avec la fonction mysql_connect() sera utilisée. Si une telle connexion n'est pas trouvée, la fonction tentera d'ouvrir une connexion, comme si la fonction mysql_connect() avait été appelée sans argument. Si aucune connexion n'est trouvée ou établie, une alerte E_WARNING est générée.
Valeurs de retour
Retourne la chaîne échappée, ou FALSE si une erreur survient.
Exemples
Exemple #1 Exemple simple avec mysql_real_escape_string()
<?php
// Connexion
$link = mysql_connect('mysql_host', 'mysql_user', 'mysql_password')
OR die(mysql_error());
// Requête
$query = sprintf("SELECT * FROM users WHERE user='%s' AND password='%s'",
mysql_real_escape_string($user),
mysql_real_escape_string($password));
?>
Exemple #2 Un exemple d'attaque par injection SQL
<?php
// Nous ne vérifions pas $_POST['password'], il peut contenir ce que l'utilisateur veut ! Par exemple :
$_POST['username'] = 'aidan';
$_POST['password'] = "' OR ''='";
// Demande à la base de vérifier si un utilisateur correspond
$query = "SELECT * FROM users WHERE user='{$_POST['username']}' AND password='{$_POST['password']}'";
mysql_query($query);
// Cela signifie que la requête envoyée à MySQL sera :
echo $query;
?>
La requête envoyée à MySQL :
SELECT * FROM users WHERE user='aidan' AND password='' OR ''=''
Cela permet à n'importe qui de s'identifier sans mot de passe valide.
Notes
Note:
Une connexion MySQL est nécessaire avant d'utiliser la fonction mysql_real_escape_string(), sinon, une erreur de niveau E_WARNING sera générée, et FALSE sera retourné. Si link_identifier n'est pas défini, la dernière connexion MySQL est utilisée.
Note:
Si magic_quotes_gpc est activée, appliquez d'abord la fonction stripslashes() à vos données. Utiliser cette fonction sur des données qui ont déjà été protégées, les protégera une deuxième fois.
Note:
Si cette fonction n'est pas utilisée pour protéger vos données, la requête sera vulnérable aux attaques par injection SQL.
Note: mysql_real_escape_string() n'échappe ni %, ni _. Ce sont des jokers en MySQL si combinés avec LIKE, GRANT, ou REVOKE.
Voir aussi
- mysql_client_encoding() - Retourne le nom du jeu de caractères utilisé par le client MySQL
- addslashes() - Ajoute des antislashs dans une chaîne
- stripslashes() - Supprime les antislashs d'une chaîne
- La directive magic_quotes_gpc
- La directive magic_quotes_runtime
add a note
User Contributed Notes
mysql_real_escape_string
hnpilot
12-Feb-2012 04:16
sainthyoga2003 at gmail dot com
16-Jan-2012 12:15
exactly, how to use this function for making good sql sentences?
using this function and i get the following:
Select * from table where attribute = \'menu\'
and obviously, this is a syntax error
ovoznyak at gmail dot com
07-Jan-2012 04:25
Function safe_string_escape($str) above is not properly working when $str is numeric (not string).
For example, when call them as safe_string_escape((int) 12), it returns empty string. At the same time mysql_real_escape_string() returns 12.
So, it is safe to add $str = (string) $str; in the begin of function.
Anonymous
04-Oct-2011 05:34
If you try to escape a string which contains signs such as ’ or " and it doesnt work, check your website/file charset! Maybe it is NOT utf-8 ;)
upadrian at gmail dot com
05-Aug-2011 12:28
<?php
/**
* @author upadrian@gmail.com
* Simplified version for array escape using mysql_real_escape_string
* for db store. Key names are not escaped beacuse i don't plain to
* include in a sql.
*
*/
function mres($q) {
if(is_array($q))
foreach($q as $k => $v)
$q[$k] = mres($v); //recursive
elseif(is_string($q))
$q = mysql_real_escape_string($q);
return $q;
}
?>
dan at marginallyclever dot com
08-Mar-2011 02:43
// Simplify, and don't forget to check the key names.
function from_array($x=null) {
if(!isset($x)) return null;
else if(is_string($x)) return mysql_real_escape_string($x);
else if(is_array($x)) {
foreach($x as $k=>$v) {
$k2=mysql_real_escape_string($k);
if($k!=$k2) unset($x[$k]);
$x[$k2]=from_array($v);
}
return $x;
}
}
// call it with $x=from_array($_POST['key_name']);
// or even $_POST=from_array($_POST);
stefan dot van dot beusekom at gmail dot com
31-Jan-2011 06:36
Following is a recursive function that makes all the strings it finds safe for data entry. If the underlying value is an array, it will loop through that array as well, to inifity. So any array depth is allowed. This might come in handy when dealing with sessions, posts, gets or whatnot arrays, where you immediately want to make use of the data without having to filter the data first.
<?php
/*
* Created by: Stefan van Beusekom
* Created on: 31-01-2011
* Description: A method that ensures safe data entry, and accepts either strings or arrays. If the array is multidimensional,
* it will recursively loop through the array and make all points of data safe for entry.
* parameters: string or array;
* return: string or array;
*/
public function filterParameters($array) {
// Check if the parameter is an array
if(is_array($array)) {
// Loop through the initial dimension
foreach($array as $key => $value) {
// Check if any nodes are arrays themselves
if(is_array($array[$key]))
// If they are, let the function call itself over that particular node
$array[$key] = $this->filterParameters($array[$key]);
// Check if the nodes are strings
if(is_string($array[$key]))
// If they are, perform the real escape function over the selected node
$array[$key] = mysql_real_escape_string($array[$key]);
}
}
// Check if the parameter is a string
if(is_string($array))
// If it is, perform a mysql_real_escape_string on the parameter
$array = mysql_real_escape_string($array);
// Return the filtered result
return $array;
}
?>
feedr
05-Dec-2010 09:38
Just a little function which mimics the original mysql_real_escape_string but which doesn't need an active mysql connection. Could be implemented as a static function in a database class. Hope it helps someone.
<?php
function mysql_escape_mimic($inp) {
if(is_array($inp))
return array_map(__METHOD__, $inp);
if(!empty($inp) && is_string($inp)) {
return str_replace(array('\\', "\0", "\n", "\r", "'", '"', "\x1a"), array('\\\\', '\\0', '\\n', '\\r', "\\'", '\\"', '\\Z'), $inp);
}
return $inp;
}
?>
Anonymous
10-Nov-2010 10:44
calling this function twice, or on a string for which quotes have already been escaped, causes the quotes to be escaped twice.An example is where we have to check for magic_quotes_gpc before calling mysql_escape_string to sanitize the inputs.
The following function can be used to escape singe and double quotes in a string with out the risk of escaping quotes twice.This function escapes a quote, only if it hasn't already been escaped.
<?php
function safe_string_escape($str)
{
$len=strlen($str);
$escapeCount=0;
$targetString='';
for($offset=0;$offset<$len;$offset++) {
switch($c=$str{$offset}) {
case "'":
// Escapes this quote only if its not preceded by an unescaped backslash
if($escapeCount % 2 == 0) $targetString.="\\";
$escapeCount=0;
$targetString.=$c;
break;
case '"':
// Escapes this quote only if its not preceded by an unescaped backslash
if($escapeCount % 2 == 0) $targetString.="\\";
$escapeCount=0;
$targetString.=$c;
break;
case '\\':
$escapeCount++;
$targetString.=$c;
break;
default:
$escapeCount=0;
$targetString.=$c;
}
}
return $targetString;
}
echo safe_string_escape("asda'sda\'dsad\"sadasd'");
?>
above code echoes
asda\'sda\'dsad\"sadasd\'
You can see that the second single quote wasnt escaped again..
m-t at live dot fr
17-Oct-2010 11:30
You should use mysql_real_escape_string only before inserting the data into your table, otherwise you could just use this function :
function reverse_escape($str)
{
$search=array("\\\\","\\0","\\n","\\r","\Z","\'",'\"');
$replace=array("\\","\0","\n","\r","\x1a","'",'"');
return str_replace($search,$replace,$str);
}
anonymous at host dot com
16-Sep-2010 04:28
You can also use the escape function in a manner as shown in the snapshot out of my own browsertools class:
<?php
//
// MySQL Database connection
//
public function mysqlConnect($host, $user, $password, $database) {
$this->mysql = mysql_connect($host, $user, $password);
if (!$this->mysql) die(mysql_error());
mysql_select_db($database, $this->mysql);
}
//
// MySQL Query
// usage:
// $query such as "SELECT * FROM users WHERE nick = '%s' AND pass = '%s'"
// where %s are the placeholders for the parameters
// call:
// $__->mysqlQuery( $query, arg0, arg1, arg2, ... )
// description:
// The parameters given to the function are escaped through mysql_real_escape_string(),
// merged with the query and then given to the mysql_query function.
// returns:
// Array of lines returned by the MySQL Database
//
public function mysqlQuery($query) {
$numParams = func_num_args();
$params = func_get_args();
if ($numParams > 1) {
for ($i = 1; $i < $numParams; $i++){
$params[$i] = mysql_real_escape_string($params[$i]);
}
$query = call_user_func_array('sprintf', $params);
}
$this->result = mysql_query($query, $this->mysql);
if (!$this->result) die(mysql_error());
$ret = array();
while ($row = mysql_fetch_assoc($this->result)) {
$ret[] = $row;
}
mysql_free_result($this->result);
return $ret;
}
?>
paralescuoctavian at gmail dot com
12-Sep-2010 07:28
Also don't forget to escape $_COOKIE array before quering the database. In firefox you can edit cookies and insert and inject harmful sql queries.
<?php
foreach ($_COOKIE as $key => $value) {
if(get_magic_quotes_gpc()) $_COOKIE[$key]=stripslashes($value);
$_COOKIE[$key] = mysql_real_escape_string($value);
}
?>
adelbenzarti at yahoo dot fr
19-Jun-2010 05:05
The function mysql_real_escape_string helps the developer to insert data without having troubles in the process or having risks of SQL Injection.
You can develop a similar function :
<?php
function escape($str)
{
$search=array("\\","\0","\n","\r","\x1a","'",'"');
$replace=array("\\\\","\\0","\\n","\\r","\Z","\'",'\"');
return str_replace($search,$replace,$str);
}
?>
manixrock -~- gmail ~-~ com
16-May-2010 06:07
I've come up with an easy way to more easily escape things in an sql query. The simpler things are, the lower the chance that you'll forget to escape something. I use a helper class:
<?php
class MysqlStringEscaper
{
function __get($value)
{
return mysql_real_escape_string($value);
}
}
$str = new MysqlStringEscaper;
?>
then whenever I run a query I can simply do:
<?php
mysql_query("SELECT * FROM users WHERE name LIKE '{$str->$name}' LIMIT 10");
?>
This way it's easy to see what the variable is escaped as (other instances like $int or $list could be implemented), it's inline and it only changes the variable when it's inserted into the query.
hikmet1023 at hotmail dot com
25-Mar-2010 02:29
about DATA LENGTH and mysql_real_escape_string
i have just experienced that this function does not harm the data length at all. It seems to use the escaped string during insertion but still insert the UNESCAPED string:
I have tried INSERTing 50 char long string ( containing characters to be escaped) into 50 char long datafield. I could SELECT the data without any loss and i didnt need to UNESCAPE it! So the data comes ready cooked, just serve it to where you need to...
AND BEFORE GOING MAD typing, saving, changing for long hours:
as documented above, do not forget to stripslashes(yourstring) if you have to.
And as documented at mysql manuals: do not use SET NAMES, use mysql_set_charset
gustavo639 at gmail dot com
25-Feb-2010 08:17
I use:
<?php
public static function escaparParametros(){
$numParametros = func_num_args();
$parametros = func_get_args();
for ($i = 0; $i < $numParametros; $i++){
$parametros[$i] = mysql_real_escape_string($parametros[$i]);
}
return $parametros;
}
?>
root at aeze dot ru
24-Feb-2010 10:42
Here my simple but very effective function for safe mysql queries.
<?php
/**
* USAGE: mysql_safe( string $query [, array $params ] )
* $query - SQL query WITHOUT any user-entered parameters. Replace parameters with "?"
* e.g. $query = "SELECT date from history WHERE login = ?"
* $params - array of parameters
*
* Example:
* mysql_safe( "SELECT secret FROM db WHERE login = ?", array($login) ); # one parameter
* mysql_safe( "SELECT secret FROM db WHERE login = ? AND password = ?", array($login, $password) ); # multiple parameters
* That will result safe query to MySQL with escaped $login and $password.
**/
function mysql_safe($query,$params=false) {
if ($params) {
foreach ($params as &$v) { $v = mysql_real_escape_string($v); } # Escaping parameters
# str_replace - replacing ? -> %s. %s is ugly in raw sql query
# vsprintf - replacing all %s to parameters
$sql_query = vsprintf( str_replace("?","'%s'",$query), $params );
$sql_query = mysql_query($sql_query); # Perfoming escaped query
} else {
$sql_query = mysql_query($query); # If no params...
}
return ($sql_query);
}
?>
presto dot dk at gmail dot com
28-Jan-2010 08:05
If you want to make sure that the ID you're using to do a query is a number, use sprint() of (int) or intval(), but don't use mysql_real_escape_string.
There is no difference between ISO-8859-1's number 10 and UTF-8's number 10.
strata_ranger at hotmail dot com
08-Dec-2009 12:17
There's an interesting quirk in the example #2 about SQL injection: AND takes priority over OR, so the injected query actually executes as WHERE (user='aidan' AND password='') OR ''='', so instead of returning a database record corresponding to an arbitrary username (in this case 'aidan'), it would actually return ALL database records. In no particular order. So an attacker might be able to log in as any account, but not necessarily with any control over which account it is.
Of course a potential attacker could simply modify their parameters to target specific users of interest:
<?php
// E.g. attacker's values
$_POST['username'] = '';
$_POST['password'] = "' OR user = 'administrator' AND '' = '";
// Malformed query
$query = "SELECT * FROM users WHERE user='$_POST[username]' AND password='$_POST[password]'";
echo $query;
// The query sent to MySQL would read:
// SELECT * FROM users WHERE user='' AND password='' OR user='administrator' AND ''='';
// which would allow anyone to gain access to the account named 'administrator'
?>
alan_a_williams [at] hotmail [dot] com
19-Aug-2009 06:17
Just a little something I like to use....
$_GET = array_map('trim', $_GET);
$_POST = array_map('trim', $_POST);
$_COOKIE = array_map('trim', $_COOKIE);
$_REQUEST = array_map('trim', $_REQUEST);
if(get_magic_quotes_gpc()):
$_GET = array_map('stripslashes', $_GET);
$_POST = array_map('stripslashes', $_POST);
$_COOKIE = array_map('stripslashes', $_COOKIE);
$_REQUEST = array_map('stripslashes', $_REQUEST);
endif;
$_GET = array_map('mysql_real_escape_string', $_GET);
$_POST = array_map('mysql_real_escape_string', $_POST);
$_COOKIE = array_map('mysql_real_escape_string', $_COOKIE);
$_REQUEST = array_map('mysql_real_escape_string', $_REQUEST);
Seems to do the trick ALOT of the time, but I'm going to be honest, it can be a [EDITED] sometimes >_>
Anonymous
02-Aug-2009 05:45
I use the following code in my database connection include file (which is of course called at the start of every page that needs to do some SQL)...
Therefore, all POST and GET vars are automatically escaped before being used anywhere in SQL statements.
<?php
//This stops SQL Injection in POST vars
foreach ($_POST as $key => $value) {
$_POST[$key] = mysql_real_escape_string($value);
}
//This stops SQL Injection in GET vars
foreach ($_GET as $key => $value) {
$_GET[$key] = mysql_real_escape_string($value);
}
?>
plgs at ozemail dot com dot au
27-Jul-2009 03:05
Don't forget that if you're using Mysqli (ie, the "improved" Mysql extension) then you need to use the corresponding mysqli function mysqli_real_escape_string(). The parameter order is also different.
Anonymous
13-Jul-2009 10:30
It is because you swapped $key and $item:
Just change this:
<?php
function mysql_safe ( $item, $key, $type )
?>
To:
<?php
function mysql_safe ( $key, $item, $type )
?>
And it will work as expected.
isaacs dot brian dot c at gmail dot com
12-Jul-2009 01:06
I had wanted to see the merits of dynamically and "automatically" applying mysql_real_escape_string() to $_GET and $_POST as arrays rather than manually each time I would type up a query. I used array_walk_recursive() to call my function "mysql_safe" to apply mysql_real_escape_string() to each key of the $_GET and $_POST arrays.
My function is part of a class, and it is called each time I connect to the database to perform a query:
<?php
class MyClass {
function mysql_safe ( $key, $item, $type )
{
switch( $type )
{
case 'get':
if( count( $_GET ) > 0 )
{
$_GET[$item] = mysql_real_escape_string( $key );
}
break;
case 'post':
if( count( $_POST ) > 0 )
{
$_POST[$item] = mysql_real_escape_string( $key );
}
break;
}
}
function safe_get ( )
{
#Flag to only run function once
if( $this->get_flag == true ) { return true; }
array_walk_recursive( $_GET, array( $this, 'mysql_safe' ), 'get' );
array_walk_recursive( $_POST, array( $this, 'mysql_safe' ), 'post' );
$this->get_flag = true;
}
}
?>
However, after using this function, I find that it does indeed work, it also creates new $_GET and $_POST values in which $item and $key are swapped. So I end up with $_GET[$item] = $key, as well as $_GET[$key] = $item. I have not yet determined if this is due to the actual coding itself, or my particular method of implementation.
[EDIT BY danbrown AT php DOT net: Contains a bugfix by "Anonymous" on 13-JUL-09 to reorder the user function parameters.]
info at saturnprods dot com
13-Jun-2009 02:37
I always use this function so I don't have to retype over and over the mysql_real_escape_string function.
<?php
function safe($value){
return mysql_real_escape_string($value);
}
?>
Then, when I am using my code, I simply use:
<?php
$name = safe($_POST["name"]);
$password = safe($_POST["password"]);
?>
kendsnyder at gmail dot com
25-Mar-2009 02:07
<?php
// Here is a simple named binding function for queries that makes SQL more readable:
// $sql = "SELECT * FROM users WHERE user = :user AND password = :password";
// mysql_bind($sql, array('user' => $user, 'password' => $password));
// mysql_query($sql);
function mysql_bind(&$sql, $vals) {
foreach ($vals as $name => $val) {
$sql = str_replace(":$name", "'" . mysql_real_escape_string($val) . "'", $sql);
}
}
?>
Bastiaan Welmers
24-Mar-2008 12:46
This function won't help you when inserting binary data, to me it will get mallformed into the database. Probably UTF-8 combinations will be translated by this function or somewhere else when inserting data when running mysql in UTF-8 mode.
A better way to insert binary data is to transfer it to hexadecimal notation like this example:
<?php
$string = $_REQUEST['string'];
$binary = file_get_contents($_FILE['file']['tmp_name']);
$string = mysql_real_escape_string($string);
$binary_hex = bin2hex($binary);
$query = "INSERT INTO `table` (`key`, `string`, `binary`, `other`) VALUES (NULL, '$string', 0x$binary_hex, '$other')";
?>
Anonymous
02-Mar-2008 11:57
My escape function:
Automatically adds quotes (unless $quotes is false), but only for strings. Null values are converted to mysql keyword "null", booleans are converted to 1 or 0, and numbers are left alone. Also can escape a single variable or recursively escape an array of unlimited depth.
<?php
function db_escape($values, $quotes = true) {
if (is_array($values)) {
foreach ($values as $key => $value) {
$values[$key] = db_escape($value, $quotes);
}
}
else if ($values === null) {
$values = 'NULL';
}
else if (is_bool($values)) {
$values = $values ? 1 : 0;
}
else if (!is_numeric($values)) {
$values = mysql_real_escape_string($values);
if ($quotes) {
$values = '"' . $values . '"';
}
}
return $values;
}
?>
matthijs at yourmediafactory dot com
27-Dec-2007 02:49
In response to Michael D - DigitalGemstones.com:
Check the example again: sprintf(%d) already does the int conversion for you, so it's both perfectly save as well as more elegant than manually casting.
user at NOSPAM dot example dot com
27-Aug-2007 07:16
if you're doing a mysql wildcard query with
LIKE, GRANT, or REVOKE
you may use addcslashes to escape the string:
<?php
$param = mysql_real_escape_string($param);
$param = addcslashes($param, '%_');
?>
brian dot folts at gmail dot com
06-Sep-2006 11:25
mysql_real_escape_string is a bit annoying when you need to do it over an array.
<?php
function mysql_real_escape_array($t){
return array_map("mysql_real_escape_string",$t);
}
?>
this one just mysql_real_escape's the whole array.
ex) <?php $_POST=mysql_real_escape_array($_POST); ?>
and then you dont have to worry about forgetting to do this.
kael dot shipman at DONTSPAMIT! dot gmail dot com
18-Jul-2006 03:19
It seems to me that you could avoid many hassels by loading valid database values into an array at the beginning of the script, then instead of using user input to query the database directly, use it to query the array you've created. For example:
<?php
//you still have to query safely, so always use cleanup functions like eric256's
$categories = sql_query("select catName from categories where pageID = ?",$_GET['pageID']);
while ($cts = @mysql_fetch_row($categories)) {
//making $cts both the name and the value of the array variable makes it easier to check for in the future.
//obviously, this naming system wouldn't work for a multidimensional array
$cat_ar[$cts[0]] = $cts[0];
}
...
//user selects sorting criteria
//this would be from a query string like '?cats[]=cha&cats[]=fah&cats[]=lah&cats[]=badValue...', etc.
$cats = $_GET['cats'];
//verify that values exist in database before building sorting query
foreach($cats as $c) {
if ($cat_ar[$c]) { //instead of in_array(); maybe I'm just lazy... (see above note)
$cats1[] = "'".mysql_real_escape_string($c)."'";
}
}
$cats = $cats1;
//$cats now contains the filtered and escaped values of the query string
$cat_query = '&& (category_name = \''.implode(' || category_name = \'',$cats).'\')';
//build a sql query insert
//$cat_query is now "&& (category_name = 'cha' || category_name = 'fah' || category_name = 'lah')" - badValue has been removed
//since all values have already been verified and escaped, you can simply use them in a query
//however, since $pageID hasn't been cleaned for this query, you still have to use your cleaning function
$items = sql_query("SELECT * FROM items i, categories c WHERE i.catID = c.catID && pageID = ? $cat_query", $pageID);
nicolas
30-May-2006 03:38
Note that mysql_real_escape_string doesn't prepend backslashes to \x00, \n, \r, and and \x1a as mentionned in the documentation, but actually replaces the character with a MySQL acceptable representation for queries (e.g. \n is replaced with the '\n' litteral). (\, ', and " are escaped as documented) This doesn't change how you should use this function, but I think it's good to know.