Class.inputfilter.php:
<?php
/** @class: InputFilter (PHP4 & PHP5, with comments)
* @project: PHP Input Filter
* @date: 10-05-2005
* @version: 1.2.2_php4/php5
* @author: Daniel Morris
* @contributors: Gianpaolo Racca, Ghislain Picard, Marco Wandschneider, Chris Tobin and Andrew Eddie.
* @copyright: Daniel Morris
* @email: dan <at> rootcube <dot> com
* @license: GNU General Public License (GPL)
*/
class InputFilter {
var $tagsArray; // default = empty array
var $attrArray; // default = empty array
var $tagsMethod; // default = 0
var $attrMethod; // default = 0
var $xssAuto; // default = 1
var $tagBlacklist = array('applet', 'body', 'bgsound', 'base', 'basefont', 'embed', 'frame', 'frameset', 'head', 'html', 'id', 'iframe', 'ilayer', 'layer', 'link', 'meta', 'name', 'object', 'script', 'style', 'title', 'xml');
var $attrBlacklist = array('action', 'background', 'codebase', 'dynsrc', 'lowsrc'); // also will strip ALL event handlers
/**
* Constructor for inputFilter class. Only first parameter is required.
* @access constructor
* @param Array $tagsArray - list of user-defined tags
* @param Array $attrArray - list of user-defined attributes
* @param int $tagsMethod - 0= allow just user-defined, 1= allow all but user-defined
* @param int $attrMethod - 0= allow just user-defined, 1= allow all but user-defined
* @param int $xssAuto - 0= only auto clean essentials, 1= allow clean blacklisted tags/attr
*/
function inputFilter($tagsArray = array(), $attrArray = array(), $tagsMethod = 0, $attrMethod = 0, $xssAuto = 1) {
// make sure user defined arrays are in lowercase
for ($i = 0; $i < count($tagsArray); $i++) $tagsArray[$i] = strtolower($tagsArray[$i]);
for ($i = 0; $i < count($attrArray); $i++) $attrArray[$i] = strtolower($attrArray[$i]);
// assign to member vars
$this->tagsArray = (array) $tagsArray;
$this->attrArray = (array) $attrArray;
$this->tagsMethod = $tagsMethod;
$this->attrMethod = $attrMethod;
$this->xssAuto = $xssAuto;
}
/**
* Method to be called by another php script. Processes for XSS and specified bad code.
* @access public
* @param Mixed $source - input string/array-of-string to be 'cleaned'
* @return String $source - 'cleaned' version of input parameter
*/
function process($source) {
// clean all elements in this array
if (is_array($source)) {
foreach($source as $key => $value)
// filter element for XSS and other 'bad' code etc.
if (is_string($value)) $source[$key] = $this->remove($this->decode($value));
return $source;
// clean this string
} else if (is_string($source)) {
// filter source for XSS and other 'bad' code etc.
return $this->remove($this->decode($source));
// return parameter as given
} else return $source;
}
/**
* Internal method to iteratively remove all unwanted tags and attributes
* @access protected
* @param String $source - input string to be 'cleaned'
* @return String $source - 'cleaned' version of input parameter
*/
function remove($source) {
$loopCounter=0;
// provides nested-tag protection
while($source != $this->filterTags($source)) {
$source = $this->filterTags($source);
$loopCounter++;
}
return $source;
}
/**
* Internal method to strip a string of certain tags
* @access protected
* @param String $source - input string to be 'cleaned'
* @return String $source - 'cleaned' version of input parameter
*/
function filterTags($source) {
// filter pass setup
$preTag = NULL;
$postTag = $source;
// find initial tag's position
$tagOpen_start = strpos($source, '<');
// interate through string until no tags left
while($tagOpen_start !== FALSE) {
// process tag interatively
$preTag .= substr($postTag, 0, $tagOpen_start);
$postTag = substr($postTag, $tagOpen_start);
$fromTagOpen = substr($postTag, 1);
// end of tag
$tagOpen_end = strpos($fromTagOpen, '>');
if ($tagOpen_end === false) break;
// next start of tag (for nested tag assessment)
$tagOpen_nested = strpos($fromTagOpen, '<');
if (($tagOpen_nested !== false) && ($tagOpen_nested < $tagOpen_end)) {
$preTag .= substr($postTag, 0, ($tagOpen_nested+1));
$postTag = substr($postTag, ($tagOpen_nested+1));
$tagOpen_start = strpos($postTag, '<');
continue;
}
$tagOpen_nested = (strpos($fromTagOpen, '<') + $tagOpen_start + 1);
$currentTag = substr($fromTagOpen, 0, $tagOpen_end);
$tagLength = strlen($currentTag);
if (!$tagOpen_end) {
$preTag .= $postTag;
$tagOpen_start = strpos($postTag, '<');
}
// iterate through tag finding attribute pairs - setup
$tagLeft = $currentTag;
$attrSet = array();
$currentSpace = strpos($tagLeft, ' ');
// is end tag
if (substr($currentTag, 0, 1) == "/") {
$isCloseTag = TRUE;
list($tagName) = explode(' ', $currentTag);
$tagName = substr($tagName, 1);
// is start tag
} else {
$isCloseTag = FALSE;
list($tagName) = explode(' ', $currentTag);
}
// excludes all "non-regular" tagnames OR no tagname OR remove if xssauto is on and tag is blacklisted
if ((!preg_match("/^[a-z][a-z0-9]*$/i", $tagName)) || (!$tagName) || ((in_array(strtolower($tagName), $this->tagBlacklist)) && ($this->xssAuto))) {
$postTag = substr($postTag, ($tagLength + 2));
$tagOpen_start = strpos($postTag, '<');
// don't append this tag
continue;
}
// this while is needed to support attribute values with spaces in!
while ($currentSpace !== FALSE) {
$fromSpace = substr($tagLeft, ($currentSpace+1));
$nextSpace = strpos($fromSpace, ' ');
$openQuotes = strpos($fromSpace, '"');
$closeQuotes = strpos(substr($fromSpace, ($openQuotes+1)), '"') + $openQuotes + 1;
// another equals exists
if (strpos($fromSpace, '=') !== FALSE) {
// opening and closing quotes exists
if (($openQuotes !== FALSE) && (strpos(substr($fromSpace, ($openQuotes+1)), '"') !== FALSE))
$attr = substr($fromSpace, 0, ($closeQuotes+1));
// one or neither exist
else $attr = substr($fromSpace, 0, $nextSpace);
// no more equals exist
} else $attr = substr($fromSpace, 0, $nextSpace);
// last attr pair
if (!$attr) $attr = $fromSpace;
// add to attribute pairs array
$attrSet[] = $attr;
// next inc
$tagLeft = substr($fromSpace, strlen($attr));
$currentSpace = strpos($tagLeft, ' ');
}
// appears in array specified by user
$tagFound = in_array(strtolower($tagName), $this->tagsArray);
// remove this tag on condition
if ((!$tagFound && $this->tagsMethod) || ($tagFound && !$this->tagsMethod)) {
// reconstruct tag with allowed attributes
if (!$isCloseTag) {
$attrSet = $this->filterAttr($attrSet);
$preTag .= '<' . $tagName;
for ($i = 0; $i < count($attrSet); $i++)
$preTag .= ' ' . $attrSet[$i];
// reformat single tags to XHTML
if (strpos($fromTagOpen, "</" . $tagName)) $preTag .= '>';
else $preTag .= ' />';
// just the tagname
} else $preTag .= '</' . $tagName . '>';
}
// find next tag's start
$postTag = substr($postTag, ($tagLength + 2));
$tagOpen_start = strpos($postTag, '<');
}
// append any code after end of tags
$preTag .= $postTag;
return $preTag;
}
/**
* Internal method to strip a tag of certain attributes
* @access protected
* @param Array $attrSet
* @return Array $newSet
*/
function filterAttr($attrSet) {
$newSet = array();
// process attributes
for ($i = 0; $i <count($attrSet); $i++) {
// skip blank spaces in tag
if (!$attrSet[$i]) continue;
// split into attr name and value
$attrSubSet = explode('=', trim($attrSet[$i]));
list($attrSubSet[0]) = explode(' ', $attrSubSet[0]);
// removes all "non-regular" attr names AND also attr blacklisted
if ((!eregi("^[a-z]*$", $attrSubSet[0])) || (($this->xssAuto) && ((in_array(strtolower($attrSubSet[0]), $this->attrBlacklist)) || (substr($attrSubSet[0], 0, 2) == 'on'))))
continue;
// xss attr value filtering
if ($attrSubSet[1]) {
// strips unicode, hex, etc
$attrSubSet[1] = str_replace('&#', '', $attrSubSet[1]);
// strip normal newline within attr value
$attrSubSet[1] = preg_replace('/\s+/', '', $attrSubSet[1]);
// strip double quotes
$attrSubSet[1] = str_replace('"', '', $attrSubSet[1]);
// [requested feature] convert single quotes from either side to doubles (Single quotes shouldn't be used to pad attr value)
if ((substr($attrSubSet[1], 0, 1) == "'") && (substr($attrSubSet[1], (strlen($attrSubSet[1]) - 1), 1) == "'"))
$attrSubSet[1] = substr($attrSubSet[1], 1, (strlen($attrSubSet[1]) - 2));
// strip slashes
$attrSubSet[1] = stripslashes($attrSubSet[1]);
}
// auto strip attr's with "javascript:
if ( ((strpos(strtolower($attrSubSet[1]), 'expression') !== false) && (strtolower($attrSubSet[0]) == 'style')) ||
(strpos(strtolower($attrSubSet[1]), 'javascript:') !== false) ||
(strpos(strtolower($attrSubSet[1]), 'behaviour:') !== false) ||
(strpos(strtolower($attrSubSet[1]), 'vbscript:') !== false) ||
(strpos(strtolower($attrSubSet[1]), 'mocha:') !== false) ||
(strpos(strtolower($attrSubSet[1]), 'livescript:') !== false)
) continue;
// if matches user defined array
$attrFound = in_array(strtolower($attrSubSet[0]), $this->attrArray);
// keep this attr on condition
if ((!$attrFound && $this->attrMethod) || ($attrFound && !$this->attrMethod)) {
// attr has value
if ($attrSubSet[1]) $newSet[] = $attrSubSet[0] . '="' . $attrSubSet[1] . '"';
// attr has decimal zero as value
else if ($attrSubSet[1] == "0") $newSet[] = $attrSubSet[0] . '="0"';
// reformat single attributes to XHTML
else $newSet[] = $attrSubSet[0] . '="' . $attrSubSet[0] . '"';
}
}
return $newSet;
}
/**
* Try to convert to plaintext
* @access protected
* @param String $source
* @return String $source
*/
function decode($source) {
// url decode
$source = html_entity_decode($source, ENT_QUOTES, "ISO-8859-1");
// convert decimal
$source = preg_replace('/&#(\d+);/me', "chr(\\1)", $source); // decimal notation
// convert hex
$source = preg_replace('/&#x([a-f0-9]+);/mei', "chr(0x\\1)", $source); // hex notation
return $source;
}
/**
* Method to be called by another php script. Processes for SQL injection
* @access public
* @param Mixed $source - input string/array-of-string to be 'cleaned'
* @param Buffer $connection - An open MySQL connection
* @return String $source - 'cleaned' version of input parameter
*/
function safeSQL($source, &$connection) {
// clean all elements in this array
if (is_array($source)) {
foreach($source as $key => $value)
// filter element for SQL injection
if (is_string($value)) $source[$key] = $this->quoteSmart($this->decode($value), $connection);
return $source;
// clean this string
} else if (is_string($source)) {
// filter source for SQL injection
if (is_string($source)) return $this->quoteSmart($this->decode($source), $connection);
// return parameter as given
} else return $source;
}
/**
* @author Chris Tobin
* @author Daniel Morris
* @access protected
* @param String $source
* @param Resource $connection - An open MySQL connection
* @return String $source
*/
function quoteSmart($source, &$connection) {
// strip slashes
if (get_magic_quotes_gpc()) $source = stripslashes($source);
// quote both numeric and text
$source = $this->escapeString($source, $connection);
return $source;
}
/**
* @author Chris Tobin
* @author Daniel Morris
* @access protected
* @param String $source
* @param Resource $connection - An open MySQL connection
* @return String $source
*/
function escapeString($string, &$connection) {
// depreciated function
if (version_compare(phpversion(), "4.3.0", "<")) mysql_escape_string($string);
// current function
else mysql_real_escape_string($string);
return $string;
}
}
?>
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