0
0
mirror of https://github.com/ezyang/htmlpurifier.git synced 2024-09-20 03:05:18 +00:00
htmlpurifier/PureHTMLDefinition.php

608 lines
21 KiB
PHP
Raw Normal View History

<?php
class PureHTMLDefinition
{
var $generator;
var $info = array();
var $info_closes_p = array(
// these are all block elements: blocks aren't allowed in P
'address' => true,
'blockquote' => true,
'dd' => true,
'dir' => true,
'div' => true,
'dl' => true,
'dt' => true,
'h1' => true,
'h2' => true,
'h3' => true,
'h4' => true,
'h5' => true,
'h6' => true,
'hr' => true,
'ol' => true,
'p' => true,
'pre' => true,
'table' => true,
'ul' => true
);
function PureHTMLDefinition() {
$this->generator = new HTML_Generator();
}
function loadData() {
// emulates the structure of the DTD
// entities: prefixed with e_ and _ replaces .
// we don't use an array because that complicates interpolation
// strings are used instead of arrays because if you use arrays,
// you have to do some hideous manipulation with array_merge()
// these are condensed, remember, with bad stuff taken out
// transforms: font, menu, dir, center
// DON'T MONKEY AROUND THIS unless you know what you are doing
// and also know the assumptions the code makes about what this
// contains for optimization purposes (see fixNesting)
$e_special_extra = 'img';
$e_special_basic = 'br | span | bdo';
$e_special = "$e_special_basic | $e_special_extra";
$e_fontstyle_extra = 'big | small';
$e_fontstyle_basic = 'tt | i | b | u | s | strike';
$e_fontstyle = "$e_fontstyle_basic | $e_fontstyle_extra";
$e_phrase_extra = 'sub | sup';
$e_phrase_basic = 'em | strong | dfn | code | q | samp | kbd | var'.
' | cite | abbr | acronym';
$e_phrase = "$e_phrase_basic | $e_phrase_extra";
$e_inline_forms = ''; // humor the dtd
$e_misc_inline = 'ins | del';
$e_misc = "$e_misc_inline";
$e_inline = "a | $e_special | $e_fontstyle | $e_phrase".
" | $e_inline_forms";
// note the casing
$e_Inline = new HTMLDTD_ChildDef_Optional("#PCDATA | $e_inline".
" | $e_misc_inline");
$e_heading = 'h1|h2|h3|h4|h5|h6';
$e_lists = 'ul | ol | dl';
$e_blocktext = 'pre | hr | blockquote | address';
$e_block = "p | $e_heading | div | $e_lists | $e_blocktext | table";
$e_Flow = new HTMLDTD_ChildDef_Optional("#PCDATA | $e_block".
" | $e_inline | $e_misc");
$e_a_content = new HTMLDTD_ChildDef_Optional("#PCDATA | $e_special".
" | $e_fontstyle | $e_phrase | $e_inline_forms | $e_misc_inline");
$e_pre_content = new HTMLDTD_ChildDef_Optional("#PCDATA | a".
" | $e_special_basic | $e_fontstyle_basic | $e_phrase_basic".
" | $e_inline_forms | $e_misc_inline");
$e_form_content = new HTMLDTD_ChildDef_Optional(''); //unused
$e_form_button_content = new HTMLDTD_ChildDef_Optional(''); // unused
$this->info['ins'] =
$this->info['del'] =
$this->info['blockquote'] =
$this->info['dd'] =
$this->info['li'] =
$this->info['div'] = new HTMLDTD_Element($e_Flow);
$this->info['em'] =
$this->info['strong'] =
$this->info['dfn'] =
$this->info['code'] =
$this->info['samp'] =
$this->info['kbd'] =
$this->info['var'] =
$this->info['code'] =
$this->info['samp'] =
$this->info['kbd'] =
$this->info['var'] =
$this->info['cite'] =
$this->info['abbr'] =
$this->info['acronym'] =
$this->info['q'] =
$this->info['sub'] =
$this->info['tt'] =
$this->info['sup'] =
$this->info['i'] =
$this->info['b'] =
$this->info['big'] =
$this->info['small'] =
$this->info['u'] =
$this->info['s'] =
$this->info['strike'] =
$this->info['bdo'] =
$this->info['span'] =
$this->info['dt'] =
$this->info['p'] =
$this->info['h1'] =
$this->info['h2'] =
$this->info['h3'] =
$this->info['h4'] =
$this->info['h5'] =
$this->info['h6'] = new HTMLDTD_Element($e_Inline);
$this->info['ol'] =
$this->info['ul'] =
new HTMLDTD_Element(
new HTMLDTD_ChildDef_Required('li')
);
$this->info['dl'] =
new HTMLDTD_Element(
new HTMLDTD_ChildDef_Required('dt|dd')
);
$this->info['address'] =
new HTMLDTD_Element(
new HTMLDTD_ChildDef_Optional("#PCDATA | p | $e_inline".
" | $e_misc_inline")
);
$this->info['img'] =
$this->info['br'] =
$this->info['hr'] = new HTMLDTD_Element(new HTMLDTD_ChildDef_Empty());
$this->info['pre'] = new HTMLDTD_Element($e_pre_content);
$this->info['a'] = new HTMLDTD_Element($e_a_content);
}
function purifyTokens($tokens) {
if (empty($this->info)) $this->loadData();
$tokens = $this->removeForeignElements($tokens);
$tokens = $this->makeWellFormed($tokens);
$tokens = $this->fixNesting($tokens);
$tokens = $this->validateAttributes($tokens);
return $tokens;
}
function removeForeignElements($tokens) {
if (empty($this->info)) $this->loadData();
$result = array();
foreach($tokens as $token) {
if (is_subclass_of($token, 'MF_Tag')) {
if (!isset($this->info[$token->name])) {
// invalid tag, generate HTML and insert in
$token = new MF_Text(
$this->generator->generateFromToken($token)
);
}
} elseif ($token->type == 'comment') {
// strip comments
continue;
} elseif ($token->type == 'text') {
} else {
continue;
}
$result[] = $token;
}
return $result;
}
function makeWellFormed($tokens) {
if (empty($this->info)) $this->loadData();
$result = array();
$current_nesting = array();
foreach ($tokens as $token) {
if (!is_subclass_of($token, 'MF_Tag')) {
$result[] = $token;
continue;
}
$info = $this->info[$token->name]; // assumption but valid
// test if it claims to be a start tag but is empty
if ($info->child_def->type == 'empty' &&
$token->type == 'start' ) {
$result[] = new MF_EmptyTag($token->name, $token->attributes);
continue;
}
// test if it claims to be empty but really is a start tag
if ($info->child_def->type != 'empty' &&
$token->type == 'empty' ) {
$result[] = new MF_StartTag($token->name, $token->attributes);
$result[] = new MF_EndTag($token->name);
continue;
}
// automatically insert empty tags
if ($token->type == 'empty') {
$result[] = $token;
continue;
}
// we give start tags precedence, so automatically accept unless...
// it's one of those special cases
if ($token->type == 'start') {
// if there's a parent, check for special case
if (!empty($current_nesting)) {
$current_parent = array_pop($current_nesting);
// check if we're closing a P tag
if ($current_parent->name == 'p' &&
isset($this->info_closes_p[$token->name])
) {
$result[] = new MF_EndTag('p');
$result[] = $token;
$current_nesting[] = $token;
continue;
}
// check if we're closing a LI tag
if ($current_parent->name == 'li' &&
$token->name == 'li'
) {
$result[] = new MF_EndTag('li');
$result[] = $token;
$current_nesting[] = $token;
continue;
}
// this is more TIDY stuff
// we should also get some TABLE related code
// mismatched h#
$current_nesting[] = $current_parent; // undo the pop
}
$result[] = $token;
$current_nesting[] = $token;
continue;
}
// sanity check
if ($token->type != 'end') continue;
// okay, we're dealing with a closing tag
// make sure that we have something open
if (empty($current_nesting)) {
$result[] = new MF_Text(
$this->generator->generateFromToken($token)
);
continue;
}
// first, check for the simplest case: everything closes neatly
// current_nesting is modified
$current_parent = array_pop($current_nesting);
if ($current_parent->name == $token->name) {
$result[] = $token;
continue;
}
// undo the array_pop
$current_nesting[] = $current_parent;
// okay, so we're trying to close the wrong tag
// scroll back the entire nest, trying to find our tag
// feature could be to specify how far you'd like to go
$size = count($current_nesting);
// -2 because -1 is the last element, but we already checked that
$skipped_tags = false;
for ($i = $size - 2; $i >= 0; $i--) {
if ($current_nesting[$i]->name == $token->name) {
// current nesting is modified
$skipped_tags = array_splice($current_nesting, $i);
break;
}
}
// we still didn't find the tag, so translate to text
if ($skipped_tags === false) {
$result[] = new MF_Text(
$this->generator->generateFromToken($token)
);
continue;
}
// okay, we found it, close all the skipped tags
// note that skipped tags contains the element we need closed
$size = count($skipped_tags);
for ($i = $size - 1; $i >= 0; $i--) {
$result[] = new MF_EndTag($skipped_tags[$i]->name);
}
// done!
}
// we're at the end now, fix all still unclosed tags
if (!empty($current_nesting)) {
$size = count($current_nesting);
for ($i = $size - 1; $i >= 0; $i--) {
$result[] = new MF_EndTag($current_nesting[$i]->name);
}
}
return $result;
}
function fixNesting($tokens) {
if (empty($this->info)) $this->loadData();
// insert implicit "parent" node, will be removed at end
array_unshift($tokens, new MF_StartTag('div'));
$tokens[] = new MF_EndTag('div');
for ($i = 0, $size = count($tokens) ; $i < $size; ) {
$child_tokens = array();
// scroll to the end of this node, and report number
for ($j = $i, $depth = 0; ; $j++) {
if ($tokens[$j]->type == 'start') {
$depth++;
// skip token assignment on first iteration
if ($depth == 1) continue;
} elseif ($tokens[$j]->type == 'end') {
$depth--;
// skip token assignment on last iteration
if ($depth == 0) break;
}
$child_tokens[] = $tokens[$j];
}
// $i is index of start token
// $j is index of end token
// have DTD child def validate children
$element_def = $this->info[$tokens[$i]->name];
$result = $element_def->child_def->validateChildren($child_tokens);
// process result
if ($result === true) {
// leave the nodes as is
} elseif($result === false) {
// WARNING WARNING WARNING!!!
// While for the original DTD, there will never be
// cascading removal, more complex ones may have such
// a problem.
// If you modify the info array such that an element
// that requires children may contain a child that requires
// children, you need to also scroll back and re-check that
// elements parent node
$length = $j - $i + 1;
// remove entire node
array_splice($tokens, $i, $length);
// change size
$size -= $length;
// ensure that we scroll to the next node
$i--;
} else {
$length = $j - $i - 1;
// replace node with $result
array_splice($tokens, $i + 1, $length, $result);
// change size
$size -= $length;
$size += count($result);
}
// scroll to next node
$i++;
while ($i < $size and $tokens[$i]->type != 'start') $i++;
}
// remove implicit divs
array_shift($tokens);
array_pop($tokens);
return $tokens;
}
function validateAttributes($tokens) {
if (empty($this->info)) $this->loadData();
}
}
class HTMLDTD_Element
{
var $child_def;
var $attr_def = array();
function HTMLDTD_Element($child_def, $attr_def = array()) {
$this->child_def = $child_def;
$this->attr_def = $attr_def;
}
}
// HTMLDTD_ChildDef and inheritance have three types of output:
// true = leave nodes as is
// false = delete parent node and all children
// array(...) = replace children nodes with these
// this is the hardest one to implement. We'll use fancy regexp tricks
// right now, we only expect it to return TRUE or FALSE (it won't attempt
// to fix the tree)
// we may end up writing custom code for each HTML case
// in order to make it self correcting
class HTMLDTD_ChildDef
{
var $type = 'custom';
var $dtd_regex;
var $_pcre_regex;
function HTMLDTD_ChildDef($dtd_regex) {
$this->dtd_regex = $dtd_regex;
$this->_compileRegex();
}
function _compileRegex() {
$raw = str_replace(' ', '', $this->dtd_regex);
if ($raw{0} != '(') {
$raw = "($raw)";
}
$reg = str_replace(',', ',?', $raw);
$reg = preg_replace('/([#a-zA-Z0-9_.-]+)/', '(,?\\0)', $reg);
$this->_pcre_regex = $reg;
}
function validateChildren($tokens_of_children) {
$list_of_children = '';
$nesting = 0; // depth into the nest
foreach ($tokens_of_children as $token) {
if (!empty($token->is_whitespace)) continue;
$is_child = ($nesting == 0); // direct
if ($token->type == 'start') {
$nesting++;
} elseif ($token->type == 'end') {
$nesting--;
}
if ($is_child) {
$list_of_children .= $token->name . ',';
}
}
$list_of_children = rtrim($list_of_children, ',');
$okay =
preg_match(
'/^'.$this->_pcre_regex.'$/',
$list_of_children
);
return (bool) $okay;
}
}
class HTMLDTD_ChildDef_Simple extends HTMLDTD_ChildDef
{
var $elements = array();
function HTMLDTD_ChildDef_Simple($elements) {
if (is_string($elements)) {
$elements = str_replace(' ', '', $elements);
$elements = explode('|', $elements);
}
$elements = array_flip($elements);
foreach ($elements as $i => $x) $elements[$i] = true;
$this->elements = $elements;
$this->gen = new HTML_Generator();
}
function validateChildren() {
trigger_error('Cannot call abstract function!', E_USER_ERROR);
}
}
class HTMLDTD_ChildDef_Required extends HTMLDTD_ChildDef_Simple
{
var $type = 'required';
function validateChildren($tokens_of_children) {
// if there are no tokens, delete parent node
if (empty($tokens_of_children)) return false;
// the new set of children
$result = array();
// current depth into the nest
$nesting = 0;
// whether or not we're deleting a node
$is_deleting = false;
// whether or not parsed character data is allowed
// this controls whether or not we silently drop a tag
// or generate escaped HTML from it
$pcdata_allowed = isset($this->elements['#PCDATA']);
// a little sanity check to make sure it's not ALL whitespace
$all_whitespace = true;
foreach ($tokens_of_children as $token) {
if (!empty($token->is_whitespace)) {
$result[] = $token;
continue;
}
$all_whitespace = false; // phew, we're not talking about whitespace
$is_child = ($nesting == 0);
if ($token->type == 'start') {
$nesting++;
} elseif ($token->type == 'end') {
$nesting--;
}
if ($is_child) {
$is_deleting = false;
if (!isset($this->elements[$token->name])) {
$is_deleting = true;
if ($pcdata_allowed) {
$result[] = new MF_Text(
$this->gen->generateFromToken($token)
);
}
continue;
}
}
if (!$is_deleting) {
$result[] = $token;
} elseif ($pcdata_allowed) {
$result[] = new MF_Text($this->gen->generateFromToken($token));
} else {
// drop silently
}
}
if (empty($result)) return false;
if ($all_whitespace) return false;
if ($tokens_of_children == $result) return true;
return $result;
}
}
// only altered behavior is that it returns an empty array
// instead of a false (to delete the node)
class HTMLDTD_ChildDef_Optional extends HTMLDTD_ChildDef_Required
{
var $type = 'optional';
function validateChildren($tokens_of_children) {
$result = parent::validateChildren($tokens_of_children);
if ($result === false) return array();
return $result;
}
}
// placeholder
class HTMLDTD_ChildDef_Empty extends HTMLDTD_ChildDef
{
var $type = 'empty';
function HTMLDTD_ChildDef_Empty() {}
function validateChildren() {
return false;
}
}
class HTMLDTD_AttrDef
{
var $def;
function HTMLDTD_AttrDef($def) {
$this->def = $def;
}
}
?>