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 $string String to be stripped of 'evil scripts' * @return string The stripped string * @since PHP4 OOP 0.0.1 */ public function Parse($string = "") { if (get_magic_quotes_gpc()) { $string = stripslashes($string); } $string = $this->removeNulls($string); // Remove JavaScript entities from early Netscape 4 versions $string = preg_replace('%&\s*\{[^}]*(\}\s*;?|$)%', '', $string); $string = $this->normalizeEntities($string); $string = $this->filterKsesTextHook($string); $string = preg_replace('%(<' . '[^>]*' . '(>|$)' . '|>)%e', "\$this->stripTags('\\1')", $string); return $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 PHP5 OOP 1.0.0 */ public function AddProtocols() { $c_args = func_num_args(); if($c_args != 1) { trigger_error("kses5::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("kses5::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 */ public function Protocols() { $c_args = func_num_args(); if($c_args != 1) { trigger_error("kses5::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 $protocol The name of the protocol to be added. * @return bool Status of adding valid protocol. * @since PHP4 OOP 0.0.1 */ public function AddProtocol($protocol = "") { if(!is_string($protocol)) { trigger_error("kses5::AddProtocol() requires a string.", E_USER_WARNING); return false; } // Remove any inadvertent ':' at the end of the protocol. if(substr($protocol, strlen($protocol) - 1, 1) == ":") { $protocol = substr($protocol, 0, strlen($protocol) - 1); } $protocol = strtolower(trim($protocol)); if($protocol == "") { trigger_error("kses5::AddProtocol() tried to add an empty/NULL protocol.", E_USER_WARNING); return false; } // prevent duplicate protocols from being added. if(!in_array($protocol, $this->allowed_protocols)) { array_push($this->allowed_protocols, $protocol); sort($this->allowed_protocols); } 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 $protocol The name of the protocol to be removed. * @return bool Status of removing valid protocol. * @since PHP5 OOP 1.0.0 */ public function RemoveProtocol($protocol = "") { if(!is_string($protocol)) { trigger_error("kses5::RemoveProtocol() requires a string.", E_USER_WARNING); return false; } // Remove any inadvertent ':' at the end of the protocol. if(substr($protocol, strlen($protocol) - 1, 1) == ":") { $protocol = substr($protocol, 0, strlen($protocol) - 1); } $protocol = strtolower(trim($protocol)); if($protocol == "") { trigger_error("kses5::RemoveProtocol() tried to remove an empty/NULL protocol.", E_USER_WARNING); return false; } // Ensures that the protocol exists before removing it. if(in_array($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 1.0.0 */ public 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("kses5::RemoveProtocols() did not receive a string or an array.", E_USER_WARNING); return false; } } /** * 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 PHP5 OOP 1.0.1 * @see AddProtocol() */ public function SetProtocols() { $c_args = func_num_args(); if($c_args != 1) { trigger_error("kses5::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("kses5::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 PHP5 OOP 1.0.2 */ public 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 PHP5 OOP 1.0.2 */ public 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 $attribs Associative array of allowed attributes - key => attribute name - value => attribute parameter * @return bool Status of Adding (X)HTML and attributes. * @since PHP4 OOP 0.0.1 */ public function AddHTML($tag = "", $attribs = array()) { if(!is_string($tag)) { trigger_error("kses5::AddHTML() requires the tag to be a string", E_USER_WARNING); return false; } $tag = strtolower(trim($tag)); if($tag == "") { trigger_error("kses5::AddHTML() tried to add an empty/NULL tag", E_USER_WARNING); return false; } if(!is_array($attribs)) { trigger_error("kses5::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($new_val1) && count($attribs) > 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; } /** * This method removes any NULL characters in $string. * * @access private * @param string $string * @return string String without any NULL/chr(173) * @since PHP4 OOP 0.0.1 */ private function removeNulls($string) { $string = preg_replace('/\0+/', '', $string); $string = preg_replace('/(\\\\0)+/', '', $string); return $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 $string * @return string String with normalized entities * @since PHP4 OOP 0.0.1 */ private function normalizeEntities($string) { # Disarm all entities by converting & to & $string = str_replace('&', '&', $string); # TODO: Change back (Keep?) the allowed entities in our entity white list # Keeps entities that start with [A-Za-z] $string = preg_replace( '/&([A-Za-z][A-Za-z0-9]{0,19});/', '&\\1;', $string ); # Change numeric entities to valid 16 bit values $string = preg_replace( '/&#0*([0-9]{1,5});/e', '\$this->normalizeEntities16bit("\\1")', $string ); # Change &XHHHHHHH (Hex digits) to 16 bit hex values $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 $i * @return string Normalized numeric entity * @see normalizeEntities() * @since PHP4 OOP 0.0.1 */ private function normalizeEntities16bit($i) { return (($i > 65535) ? "&#$i;" : "&#$i;"); } /** * 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 $string String to perfrom additional modifications on. * @return string User modified string. * @see Parse() * @since PHP5 OOP 1.0.0 */ private function filterKsesTextHook($string) { return $string; } /** * Allows for additional user defined modifications to text. * * @deprecated use filterKsesTextHook() * @param string $string * @return string * @see filterKsesTextHook() * @since PHP4 OOP 0.0.1 */ private function _hook($string) { return $this->filterKsesTextHook($string); } /** * This method goes through an array, and changes the keys to all lower case. * * @access private * @param array $in_array Associative array * @return array Modified array * @since PHP4 OOP 0.0.1 */ private function makeArrayKeysLowerCase($in_array) { $out_array = array(); if(is_array($in_array) && count($in_array) > 0) { foreach ($in_array as $in_key => $in_val) { $out_key = strtolower($in_key); $out_array[$out_key] = array(); if(is_array($in_val) && count($in_val) > 0) { foreach ($in_val as $in_key2 => $in_val2) { $out_key2 = strtolower($in_key2); $out_array[$out_key][$out_key2] = $in_val2; } } } } return $out_array; } /** * 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 $string * @return string Modified string minus disallowed/mangled (X)HTML and attributes * @since PHP4 OOP 0.0.1 */ private function stripTags($string) { $string = preg_replace('%\\\\"%', '"', $string); if (substr($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($elem)])) { # Found an HTML element not in the white list return ''; } if ($slash != '') { return "<$slash$elem>"; } # No attributes are allowed for closing elements return $this->stripAttributes("$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 combAttributes() to split them further, and then it * builds up new HTML code from the data that combAttributes() 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 $attr Text containing attributes to check for validity. * @return string Resulting valid (X)HTML or '' * @see combAttributes() * @since PHP4 OOP 0.0.1 */ private function stripAttributes($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 = $this->combAttributes($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($arreach['name'])]; if (!is_array($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->checkAttributeValue($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 $attr Text containing tag attributes for parsing * @return array Associative array containing data on attribute and value * @since PHP4 OOP 0.0.1 */ private function combAttributes($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 = $this->removeBadProtocols($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 = $this->removeBadProtocols($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 = $this->removeBadProtocols($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 { $attr = preg_replace('/^("[^"]*("|$)|\'[^\']*(\'|$)|\S)*\s*/', '', $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 $string String to check for protocols * @return string String with removed protocols * @since PHP4 OOP 0.0.1 */ private function removeBadProtocols($string) { $string = $this->RemoveNulls($string); $string = preg_replace('/\xad+/', '', $string); # deals with Opera "feature" $string2 = $string . 'a'; while ($string != $string2) { $string2 = $string; $string = preg_replace( '/^((&[^;]*;|[\sA-Za-z0-9])*)'. '(:|:|&#[Xx]3[Aa];)\s*/e', '\$this->filterProtocols("\\1")', $string ); } return $string; } /** * Helper method used by removeBadProtocols() * * 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 $string String to check for protocols * @return string String with removed protocols * @see removeBadProtocols() * @since PHP4 OOP 0.0.1 */ private function filterProtocols($string) { $string = $this->decodeEntities($string); $string = preg_replace('/\s/', '', $string); $string = $this->removeNulls($string); $string = preg_replace('/\xad+/', '', $string2); # deals with Opera "feature" $string = strtolower($string); if(is_array($this->allowed_protocols) && count($this->allowed_protocols) > 0) { foreach ($this->allowed_protocols as $one_protocol) { if (strtolower($one_protocol) == $string) { return "$string:"; } } } return ''; } /** * Controller method for performing checks on attribute values. * * This method calls the appropriate method as specified by $checkname with * the parameters $value, $vless, and $checkvalue, and returns the result * of the call. * * This method's functionality can be expanded by creating new methods * that would match checkAttributeValue[$checkname]. * * Current checks implemented are: "maxlen", "minlen", "maxval", "minval" and "valueless" * * @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 $checkvalue The value that is to be checked against * @return bool Indicates whether the check passed or not * @since PHP5 OOP 1.0.0 */ private function checkAttributeValue($value, $vless, $checkname, $checkvalue) { $ok = true; $check_attribute_method_name = 'checkAttributeValue' . ucfirst(strtolower($checkname)); if(method_exists($this, $check_attribute_method_name)) { $ok = $this->$check_attribute_method_name($value, $checkvalue, $vless); } return $ok; } /** * Helper method invoked by checkAttributeValue(). * * 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. * * @access private * @param string $value The value of the attribute to be checked. * @param int $checkvalue The maximum value allowed * @return bool Indicates whether the check passed or not * @see checkAttributeValue() * @since PHP5 OOP 1.0.0 */ private function checkAttributeValueMaxlen($value, $checkvalue) { if (strlen($value) > intval($checkvalue)) { return false; } return true; } /** * Helper method invoked by checkAttributeValue(). * * The minlen check makes sure that the attribute value has a length not * smaller than the given value. * * @access private * @param string $value The value of the attribute to be checked. * @param int $checkvalue The minimum value allowed * @return bool Indicates whether the check passed or not * @see checkAttributeValue() * @since PHP5 OOP 1.0.0 */ private function checkAttributeValueMinlen($value, $checkvalue) { if (strlen($value) < intval($checkvalue)) { return false; } return true; } /** * Helper method invoked by checkAttributeValue(). * * 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. * * @access private * @param int $value The value of the attribute to be checked. * @param int $checkvalue The maximum numeric value allowed * @return bool Indicates whether the check passed or not * @see checkAttributeValue() * @since PHP5 OOP 1.0.0 */ private function checkAttributeValueMaxval($value, $checkvalue) { if (!preg_match('/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value)) { return false; } if (intval($value) > intval($checkvalue)) { return false; } return true; } /** * Helper method invoked by checkAttributeValue(). * * The minval check checks that the attribute value is a positive integer, * and that it is not smaller than the given value. * * @access private * @param int $value The value of the attribute to be checked. * @param int $checkvalue The minimum numeric value allowed * @return bool Indicates whether the check passed or not * @see checkAttributeValue() * @since PHP5 OOP 1.0.0 */ private function checkAttributeValueMinval($value, $checkvalue) { if (!preg_match('/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value)) { return false; } if (intval($value) < ($checkvalue)) { return false; } return true; } /** * Helper method invoked by checkAttributeValue(). * * The valueless check checks if the attribute has a value * (like ) or not (