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How to enable/disable magic_quotes_gpc in PHP August 29, 2011

Posted by tournasdimitrios1 in PHP.
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The magic quotes option was introduced to help protect servers from SQL injection attacks . It effectively executes addslashes() on all information received over GET, POST or COOKIE . Unfortunately this protection isn’t perfect : there are a series of other characters that databases interpret as special not covered by this function . In addition , data not sent direct to databases must un-escaped before it can be displayed on screen . Because it’s inconsistent and ineffective , it’s not recommended that magic_quotes_gpc be enabled . Its recommended that your php scripts have programming/input filtering done so that your databases and site is protected .

You can disable magic_quotes_gpc in the .htaccess file by adding :
# Disable magic_quotes_gpc
php_flag magic_quotes_gpc off
If your PHP script needs magic_quotes_gpc enabled , you can enable it in the .htaccess file by adding :
# Enable magic_quotes_gpc
php_flag magic_quotes_gpc on
If you get a 500 internal server error once you have put the above settings in your .htaccess file , remove them from the .htaccess file and add the following to your php file :
To disable :  ini_set (‘magic_quotes_gpc’, 0);
To enable :   ini_set (‘magic_quotes_gpc’, 1);

  • If the server has magic_quotes enabled and you want to display the values , use this command to remove the extra slashes :
    stripslashes($_POST['some-value']) ;
  • If the server has magic_quotes disabled , you can display the values directly on the screen ( they haven’t modified by the server ) . But before sending these values to the database , they must  sanitized with commands like :
    $value = mysql_real_escape_string($_POST['some-value']) ;
    =====OR========
    $value = filter_var($_POST['question'] , FILTER_SANITIZE_MAGIC_QUOTES ) ;

The filter extension (FILTER_SANITIZE_xxxxx) is enabled by default as of PHP 5.2.0 . Before this time an experimental PECL extension was used , however , the PECL version is no longer recommended or updated . Just run a phpinfo() file , a configuration block “filter” with “Input Validation and Filtering ” will confirm that the server supports this functionality .

A good practice for displaying $_POST or $_GET content  is to apply the following code :


function unescape($text)
{
  if(get_magic_quotes_gpc())
  {
    $text = stripslashes($text);
  }
  return($text);
}
# usage
echo "You entered: " . unescape($_POST['input'])."\n";
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Comments»

1. Submission to search engines - January 4, 2013

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tournasdimitrios1 - January 4, 2013

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