allowed_protocols = array('http', 'ftp', 'mailto'); $this->allowed_html = array(); } /** * Basic task of kses - parses $string and strips it as required. * * This method strips all the disallowed (X)HTML tags, attributes * and protocols from the input $string. * * @access public * @param string $string String to be stripped of 'evil scripts' * @return string The stripped string * @since PHP4 OOP 0.2.1 */ function Parse($string = "") { if (get_magic_quotes_gpc()) { $string = stripslashes($string); } $string = $this->_no_null($string); $string = $this->_js_entities($string); $string = $this->_normalize_entities($string); $string = $this->filterKsesTextHook($string); return $this->_split($string); } /** * Allows for single/batch addition of protocols * * This method accepts one argument that can be either a string * or an array of strings. Invalid data will be ignored. * * The argument will be processed, and each string will be added * via AddProtocol(). * * @access public * @param mixed , A string or array of protocols that will be added to the internal list of allowed protocols. * @return bool Status of adding valid protocols. * @see AddProtocol() * @since PHP4 OOP 0.2.1 */ function AddProtocols() { $c_args = func_num_args(); if($c_args != 1) { trigger_error("kses4::AddProtocols() did not receive an argument.", E_USER_WARNING); return false; } $protocol_data = func_get_arg(0); if(is_array($protocol_data) && count($protocol_data) > 0) { foreach($protocol_data as $protocol) { $this->AddProtocol($protocol); } return true; } elseif(is_string($protocol_data)) { $this->AddProtocol($protocol_data); return true; } else { trigger_error("kses4::AddProtocols() did not receive a string or an array.", E_USER_WARNING); return false; } } /** * Allows for single/batch addition of protocols * * @deprecated Use AddProtocols() * @see AddProtocols() * @return bool * @since PHP4 OOP 0.0.1 */ function Protocols() { $c_args = func_num_args(); if($c_args != 1) { trigger_error("kses4::Protocols() did not receive an argument.", E_USER_WARNING); return false; } return $this->AddProtocols(func_get_arg(0)); } /** * Adds a single protocol to $this->allowed_protocols. * * This method accepts a string argument and adds it to * the list of allowed protocols to keep when performing * Parse(). * * @access public * @param string $protocol The name of the protocol to be added. * @return bool Status of adding valid protocol. * @since PHP4 OOP 0.0.1 */ function AddProtocol($protocol = "") { if(!is_string($protocol)) { trigger_error("kses4::AddProtocol() requires a string.", E_USER_WARNING); return false; } $protocol = strtolower(trim($protocol)); if($protocol == "") { trigger_error("kses4::AddProtocol() tried to add an empty/NULL protocol.", E_USER_WARNING); return false; } // Remove any inadvertent ':' at the end of the protocol. if(substr($protocol, strlen($protocol) - 1, 1) == ":") { $protocol = substr($protocol, 0, strlen($protocol) - 1); } if(!in_array($protocol, $this->allowed_protocols)) { array_push($this->allowed_protocols, $protocol); sort($this->allowed_protocols); } return true; } /** * Allows for single/batch replacement of protocols * * This method accepts one argument that can be either a string * or an array of strings. Invalid data will be ignored. * * Existing protocols will be removed, then the argument will be * processed, and each string will be added via AddProtocol(). * * @access public * @param mixed , A string or array of protocols that will be the new internal list of allowed protocols. * @return bool Status of replacing valid protocols. * @since PHP4 OOP 0.2.2 * @see AddProtocol() */ function SetProtocols() { $c_args = func_num_args(); if($c_args != 1) { trigger_error("kses4::SetProtocols() did not receive an argument.", E_USER_WARNING); return false; } $protocol_data = func_get_arg(0); if(is_array($protocol_data) && count($protocol_data) > 0) { $this->allowed_protocols = array(); foreach($protocol_data as $protocol) { $this->AddProtocol($protocol); } return true; } elseif(is_string($protocol_data)) { $this->allowed_protocols = array(); $this->AddProtocol($protocol_data); return true; } else { trigger_error("kses4::SetProtocols() did not receive a string or an array.", E_USER_WARNING); return false; } } /** * Raw dump of allowed protocols * * This returns an indexed array of allowed protocols for a particular KSES * instantiation. * * @access public * @return array The list of allowed protocols. * @since PHP4 OOP 0.2.2 */ function DumpProtocols() { return $this->allowed_protocols; } /** * Raw dump of allowed (X)HTML elements * * This returns an indexed array of allowed (X)HTML elements and attributes * for a particular KSES instantiation. * * @access public * @return array The list of allowed elements. * @since PHP4 OOP 0.2.2 */ function DumpElements() { return $this->allowed_html; } /** * Adds valid (X)HTML with corresponding attributes that will be kept when stripping 'evil scripts'. * * This method accepts one argument that can be either a string * or an array of strings. Invalid data will be ignored. * * @access public * @param string $tag (X)HTML tag that will be allowed after stripping text. * @param array $attribs Associative array of allowed attributes - key => attribute name - value => attribute parameter * @return bool Status of Adding (X)HTML and attributes. * @since PHP4 OOP 0.0.1 */ function AddHTML($tag = "", $attribs = array()) { if(!is_string($tag)) { trigger_error("kses4::AddHTML() requires the tag to be a string", E_USER_WARNING); return false; } $tag = strtolower(trim($tag)); if($tag == "") { trigger_error("kses4::AddHTML() tried to add an empty/NULL tag", E_USER_WARNING); return false; } if(!is_array($attribs)) { trigger_error("kses4::AddHTML() requires an array (even an empty one) of attributes for '$tag'", E_USER_WARNING); return false; } $new_attribs = array(); if(is_array($attribs) && count($attribs) > 0) { foreach($attribs as $idx1 => $val1) { $new_idx1 = strtolower($idx1); $new_val1 = $attribs[$idx1]; if(is_array($new_val1) && count($new_val1) > 0) { $tmp_val = array(); foreach($new_val1 as $idx2 => $val2) { $new_idx2 = strtolower($idx2); $tmp_val[$new_idx2] = $val2; } $new_val1 = $tmp_val; } $new_attribs[$new_idx1] = $new_val1; } } $this->allowed_html[$tag] = $new_attribs; return true; } /** * Removes a single protocol from $this->allowed_protocols. * * This method accepts a string argument and removes it from * the list of allowed protocols to keep when performing * Parse(). * * @access public * @param string $protocol The name of the protocol to be removed. * @return bool Status of removing valid protocol. * @since PHP4 OOP 0.2.1 */ function RemoveProtocol($protocol = "") { if(!is_string($protocol)) { trigger_error("kses4::RemoveProtocol() requires a string.", E_USER_WARNING); return false; } // Remove any inadvertent ':' at the end of the protocol. if(substr($protocol, strlen($protocol) - 1, 1) == ":") { $protocol = substr($protocol, 0, strlen($protocol) - 1); } $protocol = strtolower(trim($protocol)); if($protocol == "") { trigger_error("kses4::RemoveProtocol() tried to remove an empty/NULL protocol.", E_USER_WARNING); return false; } // Ensures that the protocol exists before removing it. if(in_array($protocol, $this->allowed_protocols)) { $this->allowed_protocols = array_diff($this->allowed_protocols, array($protocol)); sort($this->allowed_protocols); } return true; } /** * Allows for single/batch removal of protocols * * This method accepts one argument that can be either a string * or an array of strings. Invalid data will be ignored. * * The argument will be processed, and each string will be removed * via RemoveProtocol(). * * @access public * @param mixed , A string or array of protocols that will be removed from the internal list of allowed protocols. * @return bool Status of removing valid protocols. * @see RemoveProtocol() * @since PHP5 OOP 0.2.1 */ function RemoveProtocols() { $c_args = func_num_args(); if($c_args != 1) { return false; } $protocol_data = func_get_arg(0); if(is_array($protocol_data) && count($protocol_data) > 0) { foreach($protocol_data as $protocol) { $this->RemoveProtocol($protocol); } } elseif(is_string($protocol_data)) { $this->RemoveProtocol($protocol_data); return true; } else { trigger_error("kses4::RemoveProtocols() did not receive a string or an array.", E_USER_WARNING); return false; } } /** * This method removes any NULL or characters in $string. * * @access private * @param string $string * @return string String without any NULL/chr(173) * @since PHP4 OOP 0.0.1 */ function _no_null($string) { $string = preg_replace('/\0+/', '', $string); $string = preg_replace('/(\\\\0)+/', '', $string); return $string; } /** * This function removes the HTML JavaScript entities found in early versions of * Netscape 4. * * @access private * @param string $string * @return string String without any NULL/chr(173) * @since PHP4 OOP 0.0.1 */ function _js_entities($string) { return preg_replace('%&\s*\{[^}]*(\}\s*;?|$)%', '', $string); } /** * Normalizes HTML entities * * This function normalizes HTML entities. It will convert "AT&T" to the correct * "AT&T", ":" to ":", "&#XYZZY;" to "&#XYZZY;" and so on. * * @access private * @param string $string * @return string String with normalized entities * @since PHP4 OOP 0.0.1 */ function _normalize_entities($string) { # Disarm all entities by converting & to & $string = str_replace('&', '&', $string); # Change back the allowed entities in our entity white list $string = preg_replace('/&([A-Za-z][A-Za-z0-9]{0,19});/', '&\\1;', $string); $string = preg_replace('/&#0*([0-9]{1,5});/e', '\$this->_normalize_entities2("\\1")', $string); $string = preg_replace('/&#([Xx])0*(([0-9A-Fa-f]{2}){1,2});/', '&#\\1\\2;', $string); return $string; } /** * Helper method used by normalizeEntites() * * This method helps normalizeEntities() to only accept 16 bit values * and nothing more for &#number; entities. * * This method helps normalize_entities() during a preg_replace() * where a &#(0)*XXXXX; occurs. The '(0)*XXXXXX' value is converted to * a number and the result is returned as a numeric entity if the number * is less than 65536. Otherwise, the value is returned 'as is'. * * @access private * @param string $i * @return string Normalized numeric entity * @see _normalize_entities() * @since PHP4 OOP 0.0.1 */ function _normalize_entities2($i) { return (($i > 65535) ? "&#$i;" : "&#$i;"); } /** * Allows for additional user defined modifications to text. * * @deprecated use filterKsesTextHook() * @param string $string * @see filterKsesTextHook() * @return string * @since PHP4 OOP 0.0.1 */ function _hook($string) { return $this->filterKsesTextHook($string); } /** * Allows for additional user defined modifications to text. * * This method allows for additional modifications to be performed on * a string that's being run through Parse(). Currently, it returns the * input string 'as is'. * * This method is provided for users to extend the kses class for their own * requirements. * * @access public * @param string $string String to perfrom additional modifications on. * @return string User modified string. * @see Parse() * @since PHP5 OOP 1.0.0 */ function filterKsesTextHook($string) { return $string; } /** * This method goes through an array, and changes the keys to all lower case. * * @access private * @param array $in_array Associative array * @return array Modified array * @since PHP4 OOP 0.0.1 */ function _array_lc($inarray) { $outarray = array(); if(is_array($inarray) && count($inarray) > 0) { foreach ($inarray as $inkey => $inval) { $outkey = strtolower($inkey); $outarray[$outkey] = array(); if(is_array($inval) && count($inval) > 0) { foreach ($inval as $inkey2 => $inval2) { $outkey2 = strtolower($inkey2); $outarray[$outkey][$outkey2] = $inval2; } } } } return $outarray; } /** * This method searched for HTML tags, no matter how malformed. It also * matches stray ">" characters. * * @access private * @param string $string * @return string HTML tags * @since PHP4 OOP 0.0.1 */ function _split($string) { return preg_replace( '%(<'. # EITHER: < '[^>]*'. # things that aren't > '(>|$)'. # > or end of string '|>)%e', # OR: just a > "\$this->_split2('\\1')", $string); } /** * This method strips out disallowed and/or mangled (X)HTML tags along with assigned attributes. * * This method does a lot of work. It rejects some very malformed things * like <:::>. It returns an empty string if the element isn't allowed (look * ma, no strip_tags()!). Otherwise it splits the tag into an element and an * allowed attribute list. * * @access private * @param string $string * @return string Modified string minus disallowed/mangled (X)HTML and attributes * @since PHP4 OOP 0.0.1 */ function _split2($string) { $string = $this->_stripslashes($string); if (substr($string, 0, 1) != '<') { # It matched a ">" character return '>'; } if (!preg_match('%^<\s*(/\s*)?([a-zA-Z0-9]+)([^>]*)>?$%', $string, $matches)) { # It's seriously malformed return ''; } $slash = trim($matches[1]); $elem = $matches[2]; $attrlist = $matches[3]; if ( !isset($this->allowed_html[strtolower($elem)]) || !is_array($this->allowed_html[strtolower($elem)]) ) { # They are using a not allowed HTML element return ''; } if ($slash != '') { return "<$slash$elem>"; } # No attributes are allowed for closing elements return $this->_attr("$slash$elem", $attrlist); } /** * This method strips out disallowed attributes for (X)HTML tags. * * This method removes all attributes if none are allowed for this element. * If some are allowed it calls $this->_hair() to split them further, and then it * builds up new HTML code from the data that $this->_hair() returns. It also * removes "<" and ">" characters, if there are any left. One more thing it * does is to check if the tag has a closing XHTML slash, and if it does, * it puts one in the returned code as well. * * @access private * @param string $element (X)HTML tag to check * @param string $attr Text containing attributes to check for validity. * @return string Resulting valid (X)HTML or '' * @see _hair() * @since PHP4 OOP 0.0.1 */ function _attr($element, $attr) { # Is there a closing XHTML slash at the end of the attributes? $xhtml_slash = ''; if (preg_match('%\s/\s*$%', $attr)) { $xhtml_slash = ' /'; } # Are any attributes allowed at all for this element? if ( !isset($this->allowed_html[strtolower($element)]) || count($this->allowed_html[strtolower($element)]) == 0 ) { return "<$element$xhtml_slash>"; } # Split it $attrarr = $this->_hair($attr); # Go through $attrarr, and save the allowed attributes for this element # in $attr2 $attr2 = ''; if(is_array($attrarr) && count($attrarr) > 0) { foreach ($attrarr as $arreach) { if(!isset($this->allowed_html[strtolower($element)][strtolower($arreach['name'])])) { continue; } $current = $this->allowed_html[strtolower($element)][strtolower($arreach['name'])]; if ($current == '') { # the attribute is not allowed continue; } if (!is_array($current)) { # there are no checks $attr2 .= ' '.$arreach['whole']; } else { # there are some checks $ok = true; if(is_array($current) && count($current) > 0) { foreach ($current as $currkey => $currval) { if (!$this->_check_attr_val($arreach['value'], $arreach['vless'], $currkey, $currval)) { $ok = false; break; } } if ($ok) { # it passed them $attr2 .= ' '.$arreach['whole']; } } } } } # Remove any "<" or ">" characters $attr2 = preg_replace('/[<>]/', '', $attr2); return "<$element$attr2$xhtml_slash>"; } /** * This method combs through an attribute list string and returns an associative array of attributes and values. * * This method does a lot of work. It parses an attribute list into an array * with attribute data, and tries to do the right thing even if it gets weird * input. It will add quotes around attribute values that don't have any quotes * or apostrophes around them, to make it easier to produce HTML code that will * conform to W3C's HTML specification. It will also remove bad URL protocols * from attribute values. * * @access private * @param string $attr Text containing tag attributes for parsing * @return array Associative array containing data on attribute and value * @since PHP4 OOP 0.0.1 */ function _hair($attr) { $attrarr = array(); $mode = 0; $attrname = ''; # Loop through the whole attribute list while (strlen($attr) != 0) { # Was the last operation successful? $working = 0; switch ($mode) { case 0: # attribute name, href for instance if (preg_match('/^([-a-zA-Z]+)/', $attr, $match)) { $attrname = $match[1]; $working = $mode = 1; $attr = preg_replace('/^[-a-zA-Z]+/', '', $attr); } break; case 1: # equals sign or valueless ("selected") if (preg_match('/^\s*=\s*/', $attr)) # equals sign { $working = 1; $mode = 2; $attr = preg_replace('/^\s*=\s*/', '', $attr); break; } if (preg_match('/^\s+/', $attr)) # valueless { $working = 1; $mode = 0; $attrarr[] = array( 'name' => $attrname, 'value' => '', 'whole' => $attrname, 'vless' => 'y' ); $attr = preg_replace('/^\s+/', '', $attr); } break; case 2: # attribute value, a URL after href= for instance if (preg_match('/^"([^"]*)"(\s+|$)/', $attr, $match)) # "value" { $thisval = $this->_bad_protocol($match[1]); $attrarr[] = array( 'name' => $attrname, 'value' => $thisval, 'whole' => "$attrname=\"$thisval\"", 'vless' => 'n' ); $working = 1; $mode = 0; $attr = preg_replace('/^"[^"]*"(\s+|$)/', '', $attr); break; } if (preg_match("/^'([^']*)'(\s+|$)/", $attr, $match)) # 'value' { $thisval = $this->_bad_protocol($match[1]); $attrarr[] = array( 'name' => $attrname, 'value' => $thisval, 'whole' => "$attrname='$thisval'", 'vless' => 'n' ); $working = 1; $mode = 0; $attr = preg_replace("/^'[^']*'(\s+|$)/", '', $attr); break; } if (preg_match("%^([^\s\"']+)(\s+|$)%", $attr, $match)) # value { $thisval = $this->_bad_protocol($match[1]); $attrarr[] = array( 'name' => $attrname, 'value' => $thisval, 'whole' => "$attrname=\"$thisval\"", 'vless' => 'n' ); # We add quotes to conform to W3C's HTML spec. $working = 1; $mode = 0; $attr = preg_replace("%^[^\s\"']+(\s+|$)%", '', $attr); } break; } if ($working == 0) # not well formed, remove and try again { $attr = $this->_html_error($attr); $mode = 0; } } # special case, for when the attribute list ends with a valueless # attribute like "selected" if ($mode == 1) { $attrarr[] = array( 'name' => $attrname, 'value' => '', 'whole' => $attrname, 'vless' => 'y' ); } return $attrarr; } /** * This method removes disallowed protocols. * * This method removes all non-allowed protocols from the beginning of * $string. It ignores whitespace and the case of the letters, and it does * understand HTML entities. It does its work in a while loop, so it won't be * fooled by a string like "javascript:javascript:alert(57)". * * @access private * @param string $string String to check for protocols * @return string String with removed protocols * @since PHP4 OOP 0.0.1 */ function _bad_protocol($string) { $string = $this->_no_null($string); $string = preg_replace('/\xad+/', '', $string); # deals with Opera "feature" $string2 = $string.'a'; while ($string != $string2) { $string2 = $string; $string = $this->_bad_protocol_once($string); } # while return $string; } /** * Helper method used by _bad_protocol() * * This function searches for URL protocols at the beginning of $string, while * handling whitespace and HTML entities. * Function updated to fix security vulnerability (see http://projects.dokeos.com/index.php?do=details&task_id=2312) * * @access private * @param string $string String to check for protocols * @return string String with removed protocols * @see _bad_protocol() * @since PHP4 OOP 0.0.1 */ function _bad_protocol_once($string) { $string2 = preg_split('/:|:|:/i', $string, 2); if(isset($string2[1]) && !preg_match('%/\?%',$string2[0])) { $string = $this->_bad_protocol_once2($string2[0]).trim($string2[1]); } return $string; } /** * Helper method used by _bad_protocol_once() regex * * This function processes URL protocols, checks to see if they're in the white- * list or not, and returns different data depending on the answer. * * @access private * @param string $string String to check for protocols * @return string String with removed protocols * @see _bad_protocol() * @see _bad_protocol_once() * @since PHP4 OOP 0.0.1 */ function _bad_protocol_once2($string) { $string = $this->_decode_entities($string); $string = preg_replace('/\s/', '', $string); $string = $this->_no_null($string); $string = preg_replace('/\xad+/', '', $string); # deals with Opera "feature" $string = strtolower($string); $allowed = false; if(is_array($this->allowed_protocols) && count($this->allowed_protocols) > 0) { foreach ($this->allowed_protocols as $one_protocol) { if (strtolower($one_protocol) == $string) { $allowed = true; break; } } } if ($allowed) { return "$string:"; } else { return ''; } } /** * This function performs different checks for attribute values. * * The currently implemented checks are "maxlen", "minlen", "maxval", * "minval" and "valueless" with even more checks to come soon. * * @access private * @param string $value The value of the attribute to be checked. * @param string $vless Indicates whether the the value is supposed to be valueless * @param string $checkname The check to be performed * @param string $checkvalue The value that is to be checked against * @return bool Indicates whether the check passed or not * @since PHP4 OOP 0.0.1 */ function _check_attr_val($value, $vless, $checkname, $checkvalue) { $ok = true; switch (strtolower($checkname)) { /** * The maxlen check makes sure that the attribute value has a length not * greater than the given value. This can be used to avoid Buffer Overflows * in WWW clients and various Internet servers. */ case 'maxlen': if (strlen($value) > $checkvalue) { $ok = false; } break; /** * The minlen check makes sure that the attribute value has a length not * smaller than the given value. */ case 'minlen': if (strlen($value) < $checkvalue) { $ok = false; } break; /** * The maxval check does two things: it checks that the attribute value is * an integer from 0 and up, without an excessive amount of zeroes or * whitespace (to avoid Buffer Overflows). It also checks that the attribute * value is not greater than the given value. * This check can be used to avoid Denial of Service attacks. */ case 'maxval': if (!preg_match('/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value)) { $ok = false; } if ($value > $checkvalue) { $ok = false; } break; /** * The minval check checks that the attribute value is a positive integer, * and that it is not smaller than the given value. */ case 'minval': if (!preg_match('/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value)) { $ok = false; } if ($value < $checkvalue) { $ok = false; } break; /** * The valueless check checks if the attribute has a value * (like ) or not (