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<?php
/**
* SafeHtmlChecker
*
* checks HTML against a subset of elements to ensure safety and XHTML validation.
*
* b2evolution - {@link http://b2evolution.net/}
* Released under GNU GPL License - {@link http://b2evolution.net/about/license.html}
* @copyright (c)2003-2005 by Francois PLANQUE - {@link http://fplanque.net/}
*
* @package evocore
* @author Simon Willison, 23rd Feb 2003, modified by fplanque, sakichan
*/
if( !defined('DB_USER') ) die( 'Please, do not access this page directly.' );
/**
* SafeHtmlChecker
*
* checks HTML against a subset of elements to ensure safety and XHTML validation.
*
* @package evocore
*/
class SafeHtmlChecker
{
var $tags; // Array showing allowed attributes for tags
var $tagattrs; // Array showing URI attributes
var $uri_attrs;
var $allowed_uri_scheme;
// Internal variables
var $parser;
var $stack = array();
var $last_checked_pos;
var $error;
/**
* Constructor
*
* {@internal This gets tested in _libs.misc.simpletest.php}}
*
* @param array
* @param array
* @param array
* @param array
* @param string Input encoding to use ('ISO-8859-1', 'UTF-8', 'US-ASCII' or '' for auto-detect)
*/
function SafeHtmlChecker( & $allowed_tags, & $allowed_attributes, & $uri_attrs, & $allowed_uri_scheme, $encoding = '' )
{
$this->tags = & $allowed_tags;
$this->tagattrs = & $allowed_attributes;
$this->uri_attrs = & $uri_attrs;
$this->allowed_uri_scheme = & $allowed_uri_scheme;
$encoding = strtoupper($encoding); // we might get 'iso-8859-1' for example
$this->encoding = $encoding;
if( ! in_array( $encoding, array( 'ISO-8859-1', 'UTF-8', 'US-ASCII' ) ) )
{ // passed encoding not supported by xml_parser_create()
$this->xml_parser_encoding = ''; // auto-detect (in PHP4, in PHP5 anyway)
}
else
{
$this->xml_parser_encoding = $this->encoding;
}
$this->parser = xml_parser_create( $this->xml_parser_encoding );
$this->last_checked_pos = 0;
$this->error = false;
// Creates the parser
xml_set_object( $this->parser, $this);
// set functions to call when a start or end tag is encountered
xml_set_element_handler($this->parser, 'tag_open', 'tag_close');
// set function to call for the actual data
xml_set_character_data_handler($this->parser, 'cdata');
xml_set_default_handler($this->parser, 'default_handler');
xml_set_external_entity_ref_handler($this->parser, 'external_entity');
xml_set_unparsed_entity_decl_handler($this->parser, 'unparsed_entity');
xml_parser_set_option($this->parser, XML_OPTION_CASE_FOLDING, false);
}
function default_handler( $parser, $data)
{
// echo 'default handler: '.$data.'<br />';
}
function external_entity( $parser, $open_entity_names, $base, $system_id, $public_id)
{
// echo 'external_entity<br />';
}
function unparsed_entity( $parser, $entity_name, $base, $system_id, $public_id, $notation_name)
{
// echo 'unparsed_entity<br />';
}
/**
* check(-)
*/
function check($xhtml)
{
// Convert encoding:
if( empty($this->xml_parser_encoding) || $this->encoding != $this->xml_parser_encoding )
{ // we need to convert encoding:
if( function_exists( 'mb_convert_encoding' ) )
{ // we can convert encoding to UTF-8
$this->encoding = 'UTF-8';
// Convert XHTML:
$xhtml = mb_convert_encoding( $xhtml, 'UTF-8' );
}
}
// Open comments or '<![CDATA[' are dangerous
$xhtml = str_replace('<!', '', $xhtml);
// Convert isolated & chars
$xhtml = preg_replace( '#(\s)&(\s)#', '\\1&\\2', $xhtml );
$xhtml_head = '<?xml version="1.0"';
if( ! empty($this->encoding) )
{
$xhtml_head .= ' encoding="'.$this->encoding.'"';
}
$xhtml_head .= '?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">';
$xhtml = $xhtml_head.'<body>'.$xhtml.'</body>';
if( !xml_parse($this->parser, $xhtml) )
{
$xml_error_code = xml_get_error_code( $this->parser );
$xml_error_string = xml_error_string( $xml_error_code );
switch( $xml_error_code )
{
case XML_ERROR_TAG_MISMATCH:
$xml_error_string .= ': <code>'.$this->stack[count($this->stack)-1].'</code>';
break;
}
$pos = xml_get_current_byte_index($this->parser);
$xml_error_string .= ' near <code>'.htmlspecialchars( substr( $xhtml, $this->last_checked_pos, $pos-$this->last_checked_pos+20 ) ).'</code>';
$this->html_error( T_('Parser error: ').$xml_error_string );
}
}
/**
* tag_open(-)
*
* Called when the parser finds an opening tag
*/
function tag_open($parser, $tag, $attrs)
{
// echo "processing tag: $tag <br />\n";
$this->last_checked_pos = xml_get_current_byte_index($this->parser);
if ($tag == 'body')
{
if( count($this->stack) > 0 )
$this->html_error( T_('Tag <code>body</code> can only be used once!') );
$this->stack[] = $tag;
return;
}
$previous = $this->stack[count($this->stack)-1];
// If previous tag is illegal, no point in running tests
if (!in_array($previous, array_keys($this->tags))) {
$this->stack[] = $tag;
return;
}
// Is tag a legal tag?
if (!in_array($tag, array_keys($this->tags))) {
$this->html_error( T_('Illegal tag'). ": <code>$tag</code>" );
$this->stack[] = $tag;
return;
}
// Is tag allowed in the current context?
if (!in_array($tag, explode(' ', $this->tags[$previous]))) {
if ($previous == 'body') {
$this->html_error( sprintf( T_('Tag %s must occur inside another tag'), '<code>'.$tag.'</code>' ) );
} else {
$this->html_error( sprintf( T_('Tag %s is not allowed within tag %s'), '<code>'.$tag.'</code>', '<code>'.$previous.'</code>') );
}
}
// Are tag attributes valid?
foreach( $attrs as $attr => $value )
{
if (!isset($this->tagattrs[$tag]) || !in_array($attr, explode(' ', $this->tagattrs[$tag])))
{
$this->html_error( sprintf( T_('Tag %s may not have attribute %s'), '<code>'.$tag.'</code>', '<code>'.$attr.'</code>' ) );
}
if (in_array($attr, $this->uri_attrs))
{ // Must this attribute be checked for URIs
$matches = array();
$value = trim($value);
if( $error = validate_url( $value, $this->allowed_uri_scheme ) )
{
$this->html_error( T_('Found invalid URL: ').$error );
}
}
}
// Set previous, used for checking nesting context rules
$this->stack[] = $tag;
}
/**
* cdata(-)
*/
function cdata($parser, $cdata)
{
$this->last_checked_pos = xml_get_current_byte_index($this->parser);
// Simply check that the 'previous' tag allows CDATA
$previous = $this->stack[count($this->stack)-1];
// If previous tag is illegal, no point in running test
if (!in_array($previous, array_keys($this->tags))) {
return;
}
if (trim($cdata) != '') {
if (!in_array('#PCDATA', explode(' ', $this->tags[$previous]))) {
$this->html_error( sprintf( T_('Tag %s may not contain raw character data'), '<code>'.$previous.'</code>' ) );
}
}
}
/**
* tag_close(-)
*/
function tag_close($parser, $tag)
{
$this->last_checked_pos = xml_get_current_byte_index($this->parser);
// Move back one up the stack
array_pop($this->stack);
}
function html_error( $string )
{
$this->error = true;
errors_add( $string );
}
/**
* isOK(-)
*/
function isOK()
{
return ! $this->error;
}
}
?>
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