1067 lines
26 KiB
PHP
1067 lines
26 KiB
PHP
<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
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/**
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* CodeIgniter
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*
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* An open source application development framework for PHP 4.3.2 or newer
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*
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* @package CodeIgniter
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* @author ExpressionEngine Dev Team
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* @copyright Copyright (c) 2008 - 2010, EllisLab, Inc.
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* @license http://codeigniter.com/user_guide/license.html
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* @link http://codeigniter.com
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* @since Version 1.0
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* @filesource
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*/
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// ------------------------------------------------------------------------
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/**
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* Input Class
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*
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* Pre-processes global input data for security
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*
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* @package CodeIgniter
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* @subpackage Libraries
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* @category Input
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* @author ExpressionEngine Dev Team
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* @link http://codeigniter.com/user_guide/libraries/input.html
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*/
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class CI_Input {
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var $use_xss_clean = FALSE;
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var $xss_hash = '';
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var $ip_address = FALSE;
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var $user_agent = FALSE;
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var $allow_get_array = FALSE;
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/* never allowed, string replacement */
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var $never_allowed_str = array(
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'document.cookie' => '[removed]',
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'document.write' => '[removed]',
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'.parentNode' => '[removed]',
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'.innerHTML' => '[removed]',
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'window.location' => '[removed]',
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'-moz-binding' => '[removed]',
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'<!--' => '<!--',
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'-->' => '-->',
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'<![CDATA[' => '<![CDATA['
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);
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/* never allowed, regex replacement */
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var $never_allowed_regex = array(
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"javascript\s*:" => '[removed]',
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"expression\s*(\(|&\#40;)" => '[removed]', // CSS and IE
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"vbscript\s*:" => '[removed]', // IE, surprise!
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"Redirect\s+302" => '[removed]'
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);
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/**
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* Constructor
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*
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* Sets whether to globally enable the XSS processing
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* and whether to allow the $_GET array
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*
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* @access public
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*/
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function CI_Input()
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{
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log_message('debug', "Input Class Initialized");
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$CFG =& load_class('Config');
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$this->use_xss_clean = ($CFG->item('global_xss_filtering') === TRUE) ? TRUE : FALSE;
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$this->allow_get_array = ($CFG->item('enable_query_strings') === TRUE) ? TRUE : FALSE;
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$this->_sanitize_globals();
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}
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// --------------------------------------------------------------------
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/**
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* Sanitize Globals
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*
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* This function does the following:
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*
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* Unsets $_GET data (if query strings are not enabled)
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*
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* Unsets all globals if register_globals is enabled
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*
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* Standardizes newline characters to \n
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*
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* @access private
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* @return void
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*/
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function _sanitize_globals()
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{
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// Would kind of be "wrong" to unset any of these GLOBALS
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$protected = array('_SERVER', '_GET', '_POST', '_FILES', '_REQUEST', '_SESSION', '_ENV', 'GLOBALS', 'HTTP_RAW_POST_DATA',
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'system_folder', 'application_folder', 'BM', 'EXT', 'CFG', 'URI', 'RTR', 'OUT', 'IN');
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// Unset globals for security.
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// This is effectively the same as register_globals = off
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foreach (array($_GET, $_POST, $_COOKIE, $_SERVER, $_FILES, $_ENV, (isset($_SESSION) && is_array($_SESSION)) ? $_SESSION : array()) as $global)
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{
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if ( ! is_array($global))
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{
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if ( ! in_array($global, $protected))
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{
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unset($GLOBALS[$global]);
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}
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}
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else
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{
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foreach ($global as $key => $val)
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{
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if ( ! in_array($key, $protected))
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{
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unset($GLOBALS[$key]);
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}
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if (is_array($val))
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{
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foreach($val as $k => $v)
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{
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if ( ! in_array($k, $protected))
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{
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unset($GLOBALS[$k]);
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}
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}
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}
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}
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}
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}
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// Is $_GET data allowed? If not we'll set the $_GET to an empty array
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if ($this->allow_get_array == FALSE)
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{
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$_GET = array();
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}
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else
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{
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$_GET = $this->_clean_input_data($_GET);
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}
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// Clean $_POST Data
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$_POST = $this->_clean_input_data($_POST);
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// Clean $_COOKIE Data
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// Also get rid of specially treated cookies that might be set by a server
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// or silly application, that are of no use to a CI application anyway
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// but that when present will trip our 'Disallowed Key Characters' alarm
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// http://www.ietf.org/rfc/rfc2109.txt
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// note that the key names below are single quoted strings, and are not PHP variables
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unset($_COOKIE['$Version']);
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unset($_COOKIE['$Path']);
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unset($_COOKIE['$Domain']);
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$_COOKIE = $this->_clean_input_data($_COOKIE);
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log_message('debug', "Global POST and COOKIE data sanitized");
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}
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// --------------------------------------------------------------------
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/**
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* Clean Input Data
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*
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* This is a helper function. It escapes data and
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* standardizes newline characters to \n
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*
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* @access private
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* @param string
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* @return string
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*/
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function _clean_input_data($str)
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{
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if (is_array($str))
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{
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$new_array = array();
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foreach ($str as $key => $val)
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{
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$new_array[$this->_clean_input_keys($key)] = $this->_clean_input_data($val);
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}
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return $new_array;
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}
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// We strip slashes if magic quotes is on to keep things consistent
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if (get_magic_quotes_gpc())
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{
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$str = stripslashes($str);
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}
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// Should we filter the input data?
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if ($this->use_xss_clean === TRUE)
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{
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$str = $this->xss_clean($str);
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}
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// Standardize newlines
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if (strpos($str, "\r") !== FALSE)
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{
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$str = str_replace(array("\r\n", "\r"), "\n", $str);
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}
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return $str;
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}
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// --------------------------------------------------------------------
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/**
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* Clean Keys
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*
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* This is a helper function. To prevent malicious users
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* from trying to exploit keys we make sure that keys are
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* only named with alpha-numeric text and a few other items.
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*
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* @access private
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* @param string
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* @return string
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*/
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function _clean_input_keys($str)
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{
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if ( ! preg_match("/^[a-z0-9:_\/-]+$/i", $str))
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{
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exit('Disallowed Key Characters.');
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}
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return $str;
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}
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// --------------------------------------------------------------------
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/**
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* Fetch from array
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*
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* This is a helper function to retrieve values from global arrays
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*
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* @access private
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* @param array
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* @param string
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* @param bool
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* @return string
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*/
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function _fetch_from_array(&$array, $index = '', $xss_clean = FALSE)
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{
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if ( ! isset($array[$index]))
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{
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return FALSE;
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}
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if ($xss_clean === TRUE)
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{
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return $this->xss_clean($array[$index]);
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}
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return $array[$index];
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}
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// --------------------------------------------------------------------
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/**
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* Fetch an item from the GET array
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*
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* @access public
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* @param string
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* @param bool
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* @return string
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*/
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function get($index = '', $xss_clean = FALSE)
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{
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return $this->_fetch_from_array($_GET, $index, $xss_clean);
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}
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// --------------------------------------------------------------------
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/**
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* Fetch an item from the POST array
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*
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* @access public
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* @param string
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* @param bool
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* @return string
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*/
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function post($index = '', $xss_clean = FALSE)
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{
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return $this->_fetch_from_array($_POST, $index, $xss_clean);
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}
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// --------------------------------------------------------------------
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/**
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* Fetch an item from either the GET array or the POST
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*
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* @access public
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* @param string The index key
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* @param bool XSS cleaning
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* @return string
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*/
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function get_post($index = '', $xss_clean = FALSE)
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{
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if ( ! isset($_POST[$index]) )
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{
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return $this->get($index, $xss_clean);
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}
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else
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{
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return $this->post($index, $xss_clean);
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}
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}
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// --------------------------------------------------------------------
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/**
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* Fetch an item from the COOKIE array
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*
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* @access public
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* @param string
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* @param bool
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* @return string
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*/
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function cookie($index = '', $xss_clean = FALSE)
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{
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return $this->_fetch_from_array($_COOKIE, $index, $xss_clean);
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}
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// --------------------------------------------------------------------
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/**
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* Fetch an item from the SERVER array
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*
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* @access public
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* @param string
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* @param bool
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* @return string
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*/
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function server($index = '', $xss_clean = FALSE)
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{
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return $this->_fetch_from_array($_SERVER, $index, $xss_clean);
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}
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// --------------------------------------------------------------------
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/**
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* Fetch the IP Address
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*
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* @access public
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* @return string
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*/
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function ip_address()
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{
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if ($this->ip_address !== FALSE)
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{
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return $this->ip_address;
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}
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if (config_item('proxy_ips') != '' && $this->server('HTTP_X_FORWARDED_FOR') && $this->server('REMOTE_ADDR'))
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{
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$proxies = preg_split('/[\s,]/', config_item('proxy_ips'), -1, PREG_SPLIT_NO_EMPTY);
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$proxies = is_array($proxies) ? $proxies : array($proxies);
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$this->ip_address = in_array($_SERVER['REMOTE_ADDR'], $proxies) ? $_SERVER['HTTP_X_FORWARDED_FOR'] : $_SERVER['REMOTE_ADDR'];
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}
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elseif ($this->server('REMOTE_ADDR') AND $this->server('HTTP_CLIENT_IP'))
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{
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$this->ip_address = $_SERVER['HTTP_CLIENT_IP'];
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}
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elseif ($this->server('REMOTE_ADDR'))
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{
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$this->ip_address = $_SERVER['REMOTE_ADDR'];
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}
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elseif ($this->server('HTTP_CLIENT_IP'))
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{
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$this->ip_address = $_SERVER['HTTP_CLIENT_IP'];
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}
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elseif ($this->server('HTTP_X_FORWARDED_FOR'))
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{
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$this->ip_address = $_SERVER['HTTP_X_FORWARDED_FOR'];
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}
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if ($this->ip_address === FALSE)
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{
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$this->ip_address = '0.0.0.0';
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return $this->ip_address;
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}
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if (strstr($this->ip_address, ','))
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{
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$x = explode(',', $this->ip_address);
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$this->ip_address = trim(end($x));
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}
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if ( ! $this->valid_ip($this->ip_address))
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{
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$this->ip_address = '0.0.0.0';
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}
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return $this->ip_address;
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}
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// --------------------------------------------------------------------
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/**
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* Validate IP Address
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*
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* Updated version suggested by Geert De Deckere
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*
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* @access public
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* @param string
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* @return string
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*/
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function valid_ip($ip)
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{
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$ip_segments = explode('.', $ip);
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// Always 4 segments needed
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if (count($ip_segments) != 4)
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{
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return FALSE;
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}
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// IP can not start with 0
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if ($ip_segments[0][0] == '0')
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{
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return FALSE;
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}
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// Check each segment
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foreach ($ip_segments as $segment)
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{
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// IP segments must be digits and can not be
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// longer than 3 digits or greater then 255
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if ($segment == '' OR preg_match("/[^0-9]/", $segment) OR $segment > 255 OR strlen($segment) > 3)
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{
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return FALSE;
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}
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}
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return TRUE;
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}
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// --------------------------------------------------------------------
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/**
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* User Agent
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*
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* @access public
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* @return string
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*/
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function user_agent()
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{
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if ($this->user_agent !== FALSE)
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{
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return $this->user_agent;
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}
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$this->user_agent = ( ! isset($_SERVER['HTTP_USER_AGENT'])) ? FALSE : $_SERVER['HTTP_USER_AGENT'];
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return $this->user_agent;
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}
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// --------------------------------------------------------------------
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/**
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* Filename Security
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*
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* @access public
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* @param string
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* @return string
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*/
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function filename_security($str)
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{
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$bad = array(
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"../",
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"./",
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"<!--",
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"-->",
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"<",
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">",
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"'",
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'"',
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'&',
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'$',
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'#',
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'{',
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'}',
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'[',
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']',
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'=',
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';',
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'?',
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"%20",
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"%22",
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"%3c", // <
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"%253c", // <
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"%3e", // >
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"%0e", // >
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"%28", // (
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"%29", // )
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"%2528", // (
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"%26", // &
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"%24", // $
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"%3f", // ?
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"%3b", // ;
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"%3d" // =
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);
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return stripslashes(str_replace($bad, '', $str));
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}
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// --------------------------------------------------------------------
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/**
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* XSS Clean
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*
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* Sanitizes data so that Cross Site Scripting Hacks can be
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* prevented. This function does a fair amount of work but
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* it is extremely thorough, designed to prevent even the
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* most obscure XSS attempts. Nothing is ever 100% foolproof,
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* of course, but I haven't been able to get anything passed
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* the filter.
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*
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* Note: This function should only be used to deal with data
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* upon submission. It's not something that should
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* be used for general runtime processing.
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*
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* This function was based in part on some code and ideas I
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* got from Bitflux: http://blog.bitflux.ch/wiki/XSS_Prevention
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*
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* To help develop this script I used this great list of
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* vulnerabilities along with a few other hacks I've
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* harvested from examining vulnerabilities in other programs:
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* http://ha.ckers.org/xss.html
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*
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* @access public
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* @param string
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* @return string
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*/
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function xss_clean($str, $is_image = FALSE)
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{
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/*
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* Is the string an array?
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*
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*/
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if (is_array($str))
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{
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while (list($key) = each($str))
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{
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$str[$key] = $this->xss_clean($str[$key]);
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}
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return $str;
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}
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/*
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* Remove Invisible Characters
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*/
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$str = $this->_remove_invisible_characters($str);
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/*
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* Protect GET variables in URLs
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*/
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// 901119URL5918AMP18930PROTECT8198
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$str = preg_replace('|\&([a-z\_0-9]+)\=([a-z\_0-9]+)|i', $this->xss_hash()."\\1=\\2", $str);
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/*
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* Validate standard character entities
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*
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* Add a semicolon if missing. We do this to enable
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* the conversion of entities to ASCII later.
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*
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*/
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$str = preg_replace('#(&\#?[0-9a-z]{2,})([\x00-\x20])*;?#i', "\\1;\\2", $str);
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/*
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* Validate UTF16 two byte encoding (x00)
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*
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* Just as above, adds a semicolon if missing.
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*
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*/
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$str = preg_replace('#(&\#x?)([0-9A-F]+);?#i',"\\1\\2;",$str);
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/*
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* Un-Protect GET variables in URLs
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*/
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$str = str_replace($this->xss_hash(), '&', $str);
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/*
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* URL Decode
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*
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|
* Just in case stuff like this is submitted:
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*
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* <a href="http://%77%77%77%2E%67%6F%6F%67%6C%65%2E%63%6F%6D">Google</a>
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*
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|
* Note: Use rawurldecode() so it does not remove plus signs
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*
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|
*/
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$str = rawurldecode($str);
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/*
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|
* Convert character entities to ASCII
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|
*
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|
* This permits our tests below to work reliably.
|
|
* We only convert entities that are within tags since
|
|
* these are the ones that will pose security problems.
|
|
*
|
|
*/
|
|
|
|
$str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);
|
|
|
|
$str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", array($this, '_html_entity_decode_callback'), $str);
|
|
|
|
/*
|
|
* Remove Invisible Characters Again!
|
|
*/
|
|
$str = $this->_remove_invisible_characters($str);
|
|
|
|
/*
|
|
* Convert all tabs to spaces
|
|
*
|
|
* This prevents strings like this: ja vascript
|
|
* NOTE: we deal with spaces between characters later.
|
|
* NOTE: preg_replace was found to be amazingly slow here on large blocks of data,
|
|
* so we use str_replace.
|
|
*
|
|
*/
|
|
|
|
if (strpos($str, "\t") !== FALSE)
|
|
{
|
|
$str = str_replace("\t", ' ', $str);
|
|
}
|
|
|
|
/*
|
|
* Capture converted string for later comparison
|
|
*/
|
|
$converted_string = $str;
|
|
|
|
/*
|
|
* Not Allowed Under Any Conditions
|
|
*/
|
|
|
|
foreach ($this->never_allowed_str as $key => $val)
|
|
{
|
|
$str = str_replace($key, $val, $str);
|
|
}
|
|
|
|
foreach ($this->never_allowed_regex as $key => $val)
|
|
{
|
|
$str = preg_replace("#".$key."#i", $val, $str);
|
|
}
|
|
|
|
/*
|
|
* Makes PHP tags safe
|
|
*
|
|
* Note: XML tags are inadvertently replaced too:
|
|
*
|
|
* <?xml
|
|
*
|
|
* But it doesn't seem to pose a problem.
|
|
*
|
|
*/
|
|
if ($is_image === TRUE)
|
|
{
|
|
// Images have a tendency to have the PHP short opening and closing tags every so often
|
|
// so we skip those and only do the long opening tags.
|
|
$str = preg_replace('/<\?(php)/i', "<?\\1", $str);
|
|
}
|
|
else
|
|
{
|
|
$str = str_replace(array('<?', '?'.'>'), array('<?', '?>'), $str);
|
|
}
|
|
|
|
/*
|
|
* Compact any exploded words
|
|
*
|
|
* This corrects words like: j a v a s c r i p t
|
|
* These words are compacted back to their correct state.
|
|
*
|
|
*/
|
|
$words = array('javascript', 'expression', 'vbscript', 'script', 'applet', 'alert', 'document', 'write', 'cookie', 'window');
|
|
foreach ($words as $word)
|
|
{
|
|
$temp = '';
|
|
|
|
for ($i = 0, $wordlen = strlen($word); $i < $wordlen; $i++)
|
|
{
|
|
$temp .= substr($word, $i, 1)."\s*";
|
|
}
|
|
|
|
// We only want to do this when it is followed by a non-word character
|
|
// That way valid stuff like "dealer to" does not become "dealerto"
|
|
$str = preg_replace_callback('#('.substr($temp, 0, -3).')(\W)#is', array($this, '_compact_exploded_words'), $str);
|
|
}
|
|
|
|
/*
|
|
* Remove disallowed Javascript in links or img tags
|
|
* We used to do some version comparisons and use of stripos for PHP5, but it is dog slow compared
|
|
* to these simplified non-capturing preg_match(), especially if the pattern exists in the string
|
|
*/
|
|
do
|
|
{
|
|
$original = $str;
|
|
|
|
if (preg_match("/<a/i", $str))
|
|
{
|
|
$str = preg_replace_callback("#<a\s+([^>]*?)(>|$)#si", array($this, '_js_link_removal'), $str);
|
|
}
|
|
|
|
if (preg_match("/<img/i", $str))
|
|
{
|
|
$str = preg_replace_callback("#<img\s+([^>]*?)(\s?/?>|$)#si", array($this, '_js_img_removal'), $str);
|
|
}
|
|
|
|
if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str))
|
|
{
|
|
$str = preg_replace("#<(/*)(script|xss)(.*?)\>#si", '[removed]', $str);
|
|
}
|
|
}
|
|
while($original != $str);
|
|
|
|
unset($original);
|
|
|
|
/*
|
|
* Remove JavaScript Event Handlers
|
|
*
|
|
* Note: This code is a little blunt. It removes
|
|
* the event handler and anything up to the closing >,
|
|
* but it's unlikely to be a problem.
|
|
*
|
|
*/
|
|
$event_handlers = array('[^a-z_\-]on\w*','xmlns');
|
|
|
|
if ($is_image === TRUE)
|
|
{
|
|
/*
|
|
* Adobe Photoshop puts XML metadata into JFIF images, including namespacing,
|
|
* so we have to allow this for images. -Paul
|
|
*/
|
|
unset($event_handlers[array_search('xmlns', $event_handlers)]);
|
|
}
|
|
|
|
$str = preg_replace("#<([^><]+?)(".implode('|', $event_handlers).")(\s*=\s*[^><]*)([><]*)#i", "<\\1\\4", $str);
|
|
|
|
/*
|
|
* Sanitize naughty HTML elements
|
|
*
|
|
* If a tag containing any of the words in the list
|
|
* below is found, the tag gets converted to entities.
|
|
*
|
|
* So this: <blink>
|
|
* Becomes: <blink>
|
|
*
|
|
*/
|
|
$naughty = 'alert|applet|audio|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|isindex|layer|link|meta|object|plaintext|style|script|textarea|title|video|xml|xss';
|
|
$str = preg_replace_callback('#<(/*\s*)('.$naughty.')([^><]*)([><]*)#is', array($this, '_sanitize_naughty_html'), $str);
|
|
|
|
/*
|
|
* Sanitize naughty scripting elements
|
|
*
|
|
* Similar to above, only instead of looking for
|
|
* tags it looks for PHP and JavaScript commands
|
|
* that are disallowed. Rather than removing the
|
|
* code, it simply converts the parenthesis to entities
|
|
* rendering the code un-executable.
|
|
*
|
|
* For example: eval('some code')
|
|
* Becomes: eval('some code')
|
|
*
|
|
*/
|
|
$str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2(\\3)", $str);
|
|
|
|
/*
|
|
* Final clean up
|
|
*
|
|
* This adds a bit of extra precaution in case
|
|
* something got through the above filters
|
|
*
|
|
*/
|
|
foreach ($this->never_allowed_str as $key => $val)
|
|
{
|
|
$str = str_replace($key, $val, $str);
|
|
}
|
|
|
|
foreach ($this->never_allowed_regex as $key => $val)
|
|
{
|
|
$str = preg_replace("#".$key."#i", $val, $str);
|
|
}
|
|
|
|
/*
|
|
* Images are Handled in a Special Way
|
|
* - Essentially, we want to know that after all of the character conversion is done whether
|
|
* any unwanted, likely XSS, code was found. If not, we return TRUE, as the image is clean.
|
|
* However, if the string post-conversion does not matched the string post-removal of XSS,
|
|
* then it fails, as there was unwanted XSS code found and removed/changed during processing.
|
|
*/
|
|
|
|
if ($is_image === TRUE)
|
|
{
|
|
if ($str == $converted_string)
|
|
{
|
|
return TRUE;
|
|
}
|
|
else
|
|
{
|
|
return FALSE;
|
|
}
|
|
}
|
|
|
|
log_message('debug', "XSS Filtering completed");
|
|
return $str;
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* Random Hash for protecting URLs
|
|
*
|
|
* @access public
|
|
* @return string
|
|
*/
|
|
function xss_hash()
|
|
{
|
|
if ($this->xss_hash == '')
|
|
{
|
|
if (phpversion() >= 4.2)
|
|
mt_srand();
|
|
else
|
|
mt_srand(hexdec(substr(md5(microtime()), -8)) & 0x7fffffff);
|
|
|
|
$this->xss_hash = md5(time() + mt_rand(0, 1999999999));
|
|
}
|
|
|
|
return $this->xss_hash;
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* Remove Invisible Characters
|
|
*
|
|
* This prevents sandwiching null characters
|
|
* between ascii characters, like Java\0script.
|
|
*
|
|
* @access public
|
|
* @param string
|
|
* @return string
|
|
*/
|
|
function _remove_invisible_characters($str)
|
|
{
|
|
static $non_displayables;
|
|
|
|
if ( ! isset($non_displayables))
|
|
{
|
|
// every control character except newline (dec 10), carriage return (dec 13), and horizontal tab (dec 09),
|
|
$non_displayables = array(
|
|
'/%0[0-8bcef]/', // url encoded 00-08, 11, 12, 14, 15
|
|
'/%1[0-9a-f]/', // url encoded 16-31
|
|
'/[\x00-\x08]/', // 00-08
|
|
'/\x0b/', '/\x0c/', // 11, 12
|
|
'/[\x0e-\x1f]/' // 14-31
|
|
);
|
|
}
|
|
|
|
do
|
|
{
|
|
$cleaned = $str;
|
|
$str = preg_replace($non_displayables, '', $str);
|
|
}
|
|
while ($cleaned != $str);
|
|
|
|
return $str;
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* Compact Exploded Words
|
|
*
|
|
* Callback function for xss_clean() to remove whitespace from
|
|
* things like j a v a s c r i p t
|
|
*
|
|
* @access public
|
|
* @param type
|
|
* @return type
|
|
*/
|
|
function _compact_exploded_words($matches)
|
|
{
|
|
return preg_replace('/\s+/s', '', $matches[1]).$matches[2];
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* Sanitize Naughty HTML
|
|
*
|
|
* Callback function for xss_clean() to remove naughty HTML elements
|
|
*
|
|
* @access private
|
|
* @param array
|
|
* @return string
|
|
*/
|
|
function _sanitize_naughty_html($matches)
|
|
{
|
|
// encode opening brace
|
|
$str = '<'.$matches[1].$matches[2].$matches[3];
|
|
|
|
// encode captured opening or closing brace to prevent recursive vectors
|
|
$str .= str_replace(array('>', '<'), array('>', '<'), $matches[4]);
|
|
|
|
return $str;
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* JS Link Removal
|
|
*
|
|
* Callback function for xss_clean() to sanitize links
|
|
* This limits the PCRE backtracks, making it more performance friendly
|
|
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
|
|
* PHP 5.2+ on link-heavy strings
|
|
*
|
|
* @access private
|
|
* @param array
|
|
* @return string
|
|
*/
|
|
function _js_link_removal($match)
|
|
{
|
|
$attributes = $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]));
|
|
return str_replace($match[1], preg_replace("#href=.*?(alert\(|alert&\#40;|javascript\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);
|
|
}
|
|
|
|
/**
|
|
* JS Image Removal
|
|
*
|
|
* Callback function for xss_clean() to sanitize image tags
|
|
* This limits the PCRE backtracks, making it more performance friendly
|
|
* and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
|
|
* PHP 5.2+ on image tag heavy strings
|
|
*
|
|
* @access private
|
|
* @param array
|
|
* @return string
|
|
*/
|
|
function _js_img_removal($match)
|
|
{
|
|
$attributes = $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]));
|
|
return str_replace($match[1], preg_replace("#src=.*?(alert\(|alert&\#40;|javascript\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si", "", $attributes), $match[0]);
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* Attribute Conversion
|
|
*
|
|
* Used as a callback for XSS Clean
|
|
*
|
|
* @access public
|
|
* @param array
|
|
* @return string
|
|
*/
|
|
function _convert_attribute($match)
|
|
{
|
|
return str_replace(array('>', '<', '\\'), array('>', '<', '\\\\'), $match[0]);
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* HTML Entity Decode Callback
|
|
*
|
|
* Used as a callback for XSS Clean
|
|
*
|
|
* @access public
|
|
* @param array
|
|
* @return string
|
|
*/
|
|
function _html_entity_decode_callback($match)
|
|
{
|
|
$CFG =& load_class('Config');
|
|
$charset = $CFG->item('charset');
|
|
|
|
return $this->_html_entity_decode($match[0], strtoupper($charset));
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* HTML Entities Decode
|
|
*
|
|
* This function is a replacement for html_entity_decode()
|
|
*
|
|
* In some versions of PHP the native function does not work
|
|
* when UTF-8 is the specified character set, so this gives us
|
|
* a work-around. More info here:
|
|
* http://bugs.php.net/bug.php?id=25670
|
|
*
|
|
* @access private
|
|
* @param string
|
|
* @param string
|
|
* @return string
|
|
*/
|
|
/* -------------------------------------------------
|
|
/* Replacement for html_entity_decode()
|
|
/* -------------------------------------------------*/
|
|
|
|
/*
|
|
NOTE: html_entity_decode() has a bug in some PHP versions when UTF-8 is the
|
|
character set, and the PHP developers said they were not back porting the
|
|
fix to versions other than PHP 5.x.
|
|
*/
|
|
function _html_entity_decode($str, $charset='UTF-8')
|
|
{
|
|
if (stristr($str, '&') === FALSE) return $str;
|
|
|
|
// The reason we are not using html_entity_decode() by itself is because
|
|
// while it is not technically correct to leave out the semicolon
|
|
// at the end of an entity most browsers will still interpret the entity
|
|
// correctly. html_entity_decode() does not convert entities without
|
|
// semicolons, so we are left with our own little solution here. Bummer.
|
|
|
|
if (function_exists('html_entity_decode') && (strtolower($charset) != 'utf-8' OR version_compare(phpversion(), '5.0.0', '>=')))
|
|
{
|
|
$str = html_entity_decode($str, ENT_COMPAT, $charset);
|
|
$str = preg_replace('~&#x(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str);
|
|
return preg_replace('~&#([0-9]{2,4})~e', 'chr(\\1)', $str);
|
|
}
|
|
|
|
// Numeric Entities
|
|
$str = preg_replace('~&#x(0*[0-9a-f]{2,5});{0,1}~ei', 'chr(hexdec("\\1"))', $str);
|
|
$str = preg_replace('~&#([0-9]{2,4});{0,1}~e', 'chr(\\1)', $str);
|
|
|
|
// Literal Entities - Slightly slow so we do another check
|
|
if (stristr($str, '&') === FALSE)
|
|
{
|
|
$str = strtr($str, array_flip(get_html_translation_table(HTML_ENTITIES)));
|
|
}
|
|
|
|
return $str;
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
/**
|
|
* Filter Attributes
|
|
*
|
|
* Filters tag attributes for consistency and safety
|
|
*
|
|
* @access public
|
|
* @param string
|
|
* @return string
|
|
*/
|
|
function _filter_attributes($str)
|
|
{
|
|
$out = '';
|
|
|
|
if (preg_match_all('#\s*[a-z\-]+\s*=\s*(\042|\047)([^\\1]*?)\\1#is', $str, $matches))
|
|
{
|
|
foreach ($matches[0] as $match)
|
|
{
|
|
$out .= preg_replace("#/\*.*?\*/#s", '', $match);
|
|
}
|
|
}
|
|
|
|
return $out;
|
|
}
|
|
|
|
// --------------------------------------------------------------------
|
|
|
|
}
|
|
// END Input class
|
|
|
|
/* End of file Input.php */
|
|
/* Location: ./system/libraries/Input.php */ |