1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
|
<?php
/**
+-----------------------------------------------------------------------+
| This file is part of the Roundcube Webmail client |
| Copyright (C) 2008-2012, The Roundcube Dev Team |
| |
| Licensed under the GNU General Public License version 3 or |
| any later version with exceptions for skins & plugins. |
| See the README file for a full license statement. |
| |
| PURPOSE: |
| Utility class providing HTML sanityzer (based on Washtml class) |
+-----------------------------------------------------------------------+
| Author: Thomas Bruederli <roundcube@gmail.com> |
| Author: Aleksander Machniak <alec@alec.pl> |
| Author: Frederic Motte <fmotte@ubixis.com> |
+-----------------------------------------------------------------------+
*/
/**
* Washtml, a HTML sanityzer.
*
* Copyright (c) 2007 Frederic Motte <fmotte@ubixis.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* OVERVIEW:
*
* Wahstml take an untrusted HTML and return a safe html string.
*
* SYNOPSIS:
*
* $washer = new washtml($config);
* $washer->wash($html);
* It return a sanityzed string of the $html parameter without html and head tags.
* $html is a string containing the html code to wash.
* $config is an array containing options:
* $config['allow_remote'] is a boolean to allow link to remote images.
* $config['blocked_src'] string with image-src to be used for blocked remote images
* $config['show_washed'] is a boolean to include washed out attributes as x-washed
* $config['cid_map'] is an array where cid urls index urls to replace them.
* $config['charset'] is a string containing the charset of the HTML document if it is not defined in it.
* $washer->extlinks is a reference to a boolean that is set to true if remote images were removed. (FE: show remote images link)
*
* INTERNALS:
*
* Only tags and attributes in the static lists $html_elements and $html_attributes
* are kept, inline styles are also filtered: all style identifiers matching
* /[a-z\-]/i are allowed. Values matching colors, sizes, /[a-z\-]/i and safe
* urls if allowed and cid urls if mapped are kept.
*
* Roundcube Changes:
* - added $block_elements
* - changed $ignore_elements behaviour
* - added RFC2397 support
* - base URL support
* - invalid HTML comments removal before parsing
* - "fixing" unitless CSS values for XHTML output
* - base url resolving
*/
/**
* Utility class providing HTML sanityzer
*
* @package Framework
* @subpackage Utils
*/
class rcube_washtml
{
/* Allowed HTML elements (default) */
static $html_elements = array('a', 'abbr', 'acronym', 'address', 'area', 'b',
'basefont', 'bdo', 'big', 'blockquote', 'br', 'caption', 'center',
'cite', 'code', 'col', 'colgroup', 'dd', 'del', 'dfn', 'dir', 'div', 'dl',
'dt', 'em', 'fieldset', 'font', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'hr', 'i',
'ins', 'label', 'legend', 'li', 'map', 'menu', 'nobr', 'ol', 'p', 'pre', 'q',
's', 'samp', 'small', 'span', 'strike', 'strong', 'sub', 'sup', 'table',
'tbody', 'td', 'tfoot', 'th', 'thead', 'tr', 'tt', 'u', 'ul', 'var', 'wbr', 'img',
// form elements
'button', 'input', 'textarea', 'select', 'option', 'optgroup'
);
/* Ignore these HTML tags and their content */
static $ignore_elements = array('script', 'applet', 'embed', 'object', 'style');
/* Allowed HTML attributes */
static $html_attribs = array('name', 'class', 'title', 'alt', 'width', 'height',
'align', 'nowrap', 'col', 'row', 'id', 'rowspan', 'colspan', 'cellspacing',
'cellpadding', 'valign', 'bgcolor', 'color', 'border', 'bordercolorlight',
'bordercolordark', 'face', 'marginwidth', 'marginheight', 'axis', 'border',
'abbr', 'char', 'charoff', 'clear', 'compact', 'coords', 'vspace', 'hspace',
'cellborder', 'size', 'lang', 'dir', 'usemap', 'shape', 'media',
// attributes of form elements
'type', 'rows', 'cols', 'disabled', 'readonly', 'checked', 'multiple', 'value'
);
/* Elements which could be empty and be returned in short form (<tag />) */
static $void_elements = array('area', 'base', 'br', 'col', 'command', 'embed', 'hr',
'img', 'input', 'keygen', 'link', 'meta', 'param', 'source', 'track', 'wbr'
);
/* State for linked objects in HTML */
public $extlinks = false;
/* Current settings */
private $config = array();
/* Registered callback functions for tags */
private $handlers = array();
/* Allowed HTML elements */
private $_html_elements = array();
/* Ignore these HTML tags but process their content */
private $_ignore_elements = array();
/* Elements which could be empty and be returned in short form (<tag />) */
private $_void_elements = array();
/* Allowed HTML attributes */
private $_html_attribs = array();
/* Max nesting level */
private $max_nesting_level;
/**
* Class constructor
*/
public function __construct($p = array())
{
$this->_html_elements = array_flip((array)$p['html_elements']) + array_flip(self::$html_elements) ;
$this->_html_attribs = array_flip((array)$p['html_attribs']) + array_flip(self::$html_attribs);
$this->_ignore_elements = array_flip((array)$p['ignore_elements']) + array_flip(self::$ignore_elements);
$this->_void_elements = array_flip((array)$p['void_elements']) + array_flip(self::$void_elements);
unset($p['html_elements'], $p['html_attribs'], $p['ignore_elements'], $p['void_elements']);
$this->config = $p + array('show_washed' => true, 'allow_remote' => false, 'cid_map' => array());
}
/**
* Register a callback function for a certain tag
*/
public function add_callback($tagName, $callback)
{
$this->handlers[$tagName] = $callback;
}
/**
* Check CSS style
*/
private function wash_style($style)
{
$s = '';
foreach (explode(';', $style) as $declaration) {
if (preg_match('/^\s*([a-z\-]+)\s*:\s*(.*)\s*$/i', $declaration, $match)) {
$cssid = $match[1];
$str = $match[2];
$value = '';
while (sizeof($str) > 0 &&
preg_match('/^(url\(\s*[\'"]?([^\'"\)]*)[\'"]?\s*\)'./*1,2*/
'|rgb\(\s*[0-9]+\s*,\s*[0-9]+\s*,\s*[0-9]+\s*\)'.
'|-?[0-9.]+\s*(em|ex|px|cm|mm|in|pt|pc|deg|rad|grad|ms|s|hz|khz|%)?'.
'|#[0-9a-f]{3,6}'.
'|[a-z0-9"\', -]+'.
')\s*/i', $str, $match)
) {
if ($match[2]) {
if (($src = $this->config['cid_map'][$match[2]])
|| ($src = $this->config['cid_map'][$this->config['base_url'].$match[2]])
) {
$value .= ' url('.htmlspecialchars($src, ENT_QUOTES) . ')';
}
else if (preg_match('!^(https?:)?//[a-z0-9/._+-]+$!i', $match[2], $url)) {
if ($this->config['allow_remote']) {
$value .= ' url('.htmlspecialchars($url[0], ENT_QUOTES).')';
}
else {
$this->extlinks = true;
}
}
else if (preg_match('/^data:.+/i', $match[2])) { // RFC2397
$value .= ' url('.htmlspecialchars($match[2], ENT_QUOTES).')';
}
}
else {
// whitelist ?
$value .= ' ' . $match[0];
// #1488535: Fix size units, so width:800 would be changed to width:800px
if (preg_match('/(left|right|top|bottom|width|height)/i', $cssid)
&& preg_match('/^[0-9]+$/', $match[0])
) {
$value .= 'px';
}
}
$str = substr($str, strlen($match[0]));
}
if (isset($value[0])) {
$s .= ($s?' ':'') . $cssid . ':' . $value . ';';
}
}
}
return $s;
}
/**
* Take a node and return allowed attributes and check values
*/
private function wash_attribs($node)
{
$t = '';
$washed = '';
foreach ($node->attributes as $key => $plop) {
$key = strtolower($key);
$value = $node->getAttribute($key);
if (isset($this->_html_attribs[$key]) ||
($key == 'href' && ($value = trim($value))
&& !preg_match('!^(javascript|vbscript|data:text)!i', $value)
&& preg_match('!^([a-z][a-z0-9.+-]+:|//|#).+!i', $value))
) {
$t .= ' ' . $key . '="' . htmlspecialchars($value, ENT_QUOTES) . '"';
}
else if ($key == 'style' && ($style = $this->wash_style($value))) {
$quot = strpos($style, '"') !== false ? "'" : '"';
$t .= ' style=' . $quot . $style . $quot;
}
else if ($key == 'background' || ($key == 'src' && strtolower($node->tagName) == 'img')) { //check tagName anyway
if (($src = $this->config['cid_map'][$value])
|| ($src = $this->config['cid_map'][$this->config['base_url'].$value])
) {
$t .= ' ' . $key . '="' . htmlspecialchars($src, ENT_QUOTES) . '"';
}
else if (preg_match('/^(http|https|ftp):.+/i', $value)) {
if ($this->config['allow_remote']) {
$t .= ' ' . $key . '="' . htmlspecialchars($value, ENT_QUOTES) . '"';
}
else {
$this->extlinks = true;
if ($this->config['blocked_src']) {
$t .= ' ' . $key . '="' . htmlspecialchars($this->config['blocked_src'], ENT_QUOTES) . '"';
}
}
}
else if (preg_match('/^data:.+/i', $value)) { // RFC2397
$t .= ' ' . $key . '="' . htmlspecialchars($value, ENT_QUOTES) . '"';
}
}
else {
$washed .= ($washed ? ' ' : '') . $key;
}
}
return $t . ($washed && $this->config['show_washed'] ? ' x-washed="'.$washed.'"' : '');
}
/**
* The main loop that recurse on a node tree.
* It output only allowed tags with allowed attributes and allowed inline styles
*
* @param DOMNode $node HTML element
* @param int $level Recurrence level (safe initial value found empirically)
*/
private function dumpHtml($node, $level = 20)
{
if (!$node->hasChildNodes()) {
return '';
}
$level++;
if ($this->max_nesting_level > 0 && $level == $this->max_nesting_level - 1) {
// log error message once
if (!$this->max_nesting_level_error) {
$this->max_nesting_level_error = true;
rcube::raise_error(array('code' => 500, 'type' => 'php',
'line' => __LINE__, 'file' => __FILE__,
'message' => "Maximum nesting level exceeded (xdebug.max_nesting_level={$this->max_nesting_level})"),
true, false);
}
return '<!-- ignored -->';
}
$node = $node->firstChild;
$dump = '';
do {
switch($node->nodeType) {
case XML_ELEMENT_NODE: //Check element
$tagName = strtolower($node->tagName);
if ($callback = $this->handlers[$tagName]) {
$dump .= call_user_func($callback, $tagName,
$this->wash_attribs($node), $this->dumpHtml($node, $level), $this);
}
else if (isset($this->_html_elements[$tagName])) {
$content = $this->dumpHtml($node, $level);
$dump .= '<' . $tagName . $this->wash_attribs($node) .
($content === '' && isset($this->_void_elements[$tagName]) ? ' />' : ">$content</$tagName>");
}
else if (isset($this->_ignore_elements[$tagName])) {
$dump .= '<!-- ' . htmlspecialchars($tagName, ENT_QUOTES) . ' not allowed -->';
}
else {
$dump .= '<!-- ' . htmlspecialchars($tagName, ENT_QUOTES) . ' ignored -->';
$dump .= $this->dumpHtml($node, $level); // ignore tags not its content
}
break;
case XML_CDATA_SECTION_NODE:
$dump .= $node->nodeValue;
break;
case XML_TEXT_NODE:
$dump .= htmlspecialchars($node->nodeValue);
break;
case XML_HTML_DOCUMENT_NODE:
$dump .= $this->dumpHtml($node, $level);
break;
case XML_DOCUMENT_TYPE_NODE:
break;
default:
$dump .= '<!-- node type ' . $node->nodeType . ' -->';
}
} while($node = $node->nextSibling);
return $dump;
}
/**
* Main function, give it untrusted HTML, tell it if you allow loading
* remote images and give it a map to convert "cid:" urls.
*/
public function wash($html)
{
// Charset seems to be ignored (probably if defined in the HTML document)
$node = new DOMDocument('1.0', $this->config['charset']);
$this->extlinks = false;
$html = $this->cleanup($html);
// Find base URL for images
if (preg_match('/<base\s+href=[\'"]*([^\'"]+)/is', $html, $matches)) {
$this->config['base_url'] = $matches[1];
}
else {
$this->config['base_url'] = '';
}
// Detect max nesting level (for dumpHTML) (#1489110)
$this->max_nesting_level = (int) @ini_get('xdebug.max_nesting_level');
// Use optimizations if supported
if (version_compare(PHP_VERSION, '5.4.0', '>=')) {
@$node->loadHTML($html, LIBXML_PARSEHUGE | LIBXML_COMPACT);
}
else {
@$node->loadHTML($html);
}
return $this->dumpHtml($node);
}
/**
* Getter for config parameters
*/
public function get_config($prop)
{
return $this->config[$prop];
}
/**
* Clean HTML input
*/
private function cleanup($html)
{
// special replacements (not properly handled by washtml class)
$html_search = array(
'/(<\/nobr>)(\s+)(<nobr>)/i', // space(s) between <NOBR>
'/<title[^>]*>[^<]*<\/title>/i', // PHP bug #32547 workaround: remove title tag
'/^(\0\0\xFE\xFF|\xFF\xFE\0\0|\xFE\xFF|\xFF\xFE|\xEF\xBB\xBF)/', // byte-order mark (only outlook?)
'/<html\s[^>]+>/i', // washtml/DOMDocument cannot handle xml namespaces
);
$html_replace = array(
'\\1'.' '.'\\3',
'',
'',
'<html>',
);
$html = preg_replace($html_search, $html_replace, trim($html));
//-> Replace all of those weird MS Word quotes and other high characters
$badwordchars = array(
"\xe2\x80\x98", // left single quote
"\xe2\x80\x99", // right single quote
"\xe2\x80\x9c", // left double quote
"\xe2\x80\x9d", // right double quote
"\xe2\x80\x94", // em dash
"\xe2\x80\xa6" // elipses
);
$fixedwordchars = array(
"'",
"'",
'"',
'"',
'—',
'...'
);
$html = str_replace($badwordchars, $fixedwordchars, $html);
// PCRE errors handling (#1486856), should we use something like for every preg_* use?
if ($html === null && ($preg_error = preg_last_error()) != PREG_NO_ERROR) {
$errstr = "Could not clean up HTML message! PCRE Error: $preg_error.";
if ($preg_error == PREG_BACKTRACK_LIMIT_ERROR) {
$errstr .= " Consider raising pcre.backtrack_limit!";
}
if ($preg_error == PREG_RECURSION_LIMIT_ERROR) {
$errstr .= " Consider raising pcre.recursion_limit!";
}
rcube::raise_error(array('code' => 620, 'type' => 'php',
'line' => __LINE__, 'file' => __FILE__,
'message' => $errstr), true, false);
return '';
}
// fix (unknown/malformed) HTML tags before "wash"
$html = preg_replace_callback('/(<(?!\!)[\/]*)([^\s>]+)([^>]*)/', array($this, 'html_tag_callback'), $html);
// Remove invalid HTML comments (#1487759)
// Don't remove valid conditional comments
// Don't remove MSOutlook (<!-->) conditional comments (#1489004)
$html = preg_replace('/<!--[^->\[\n]+>/', '', $html);
// fix broken nested lists
self::fix_broken_lists($html);
// turn relative into absolute urls
$html = self::resolve_base($html);
return $html;
}
/**
* Callback function for HTML tags fixing
*/
public static function html_tag_callback($matches)
{
$tagname = $matches[2];
$tagname = preg_replace(array(
'/:.*$/', // Microsoft's Smart Tags <st1:xxxx>
'/[^a-z0-9_\[\]\!-]/i', // forbidden characters
), '', $tagname);
// fix invalid closing tags - remove any attributes (#1489446)
if ($matches[1] == '</') {
$matches[3] = '';
}
return $matches[1] . $tagname . $matches[3];
}
/**
* Convert all relative URLs according to a <base> in HTML
*/
public static function resolve_base($body)
{
// check for <base href=...>
if (preg_match('!(<base.*href=["\']?)([hftps]{3,5}://[a-z0-9/.%-]+)!i', $body, $regs)) {
$replacer = new rcube_base_replacer($regs[2]);
$body = $replacer->replace($body);
}
return $body;
}
/**
* Fix broken nested lists, they are not handled properly by DOMDocument (#1488768)
*/
public static function fix_broken_lists(&$html)
{
// do two rounds, one for <ol>, one for <ul>
foreach (array('ol', 'ul') as $tag) {
$pos = 0;
while (($pos = stripos($html, '<' . $tag, $pos)) !== false) {
$pos++;
// make sure this is an ol/ul tag
if (!in_array($html[$pos+2], array(' ', '>'))) {
continue;
}
$p = $pos;
$in_li = false;
$li_pos = 0;
while (($p = strpos($html, '<', $p)) !== false) {
$tt = strtolower(substr($html, $p, 4));
// li open tag
if ($tt == '<li>' || $tt == '<li ') {
$in_li = true;
$p += 4;
}
// li close tag
else if ($tt == '</li' && in_array($html[$p+4], array(' ', '>'))) {
$li_pos = $p;
$p += 4;
$in_li = false;
}
// ul/ol closing tag
else if ($tt == '</' . $tag && in_array($html[$p+4], array(' ', '>'))) {
break;
}
// nested ol/ul element out of li
else if (!$in_li && $li_pos && ($tt == '<ol>' || $tt == '<ol ' || $tt == '<ul>' || $tt == '<ul ')) {
// find closing tag of this ul/ol element
$element = substr($tt, 1, 2);
$cpos = $p;
do {
$tpos = stripos($html, '<' . $element, $cpos+1);
$cpos = stripos($html, '</' . $element, $cpos+1);
}
while ($tpos !== false && $cpos !== false && $cpos > $tpos);
// not found, this is invalid HTML, skip it
if ($cpos === false) {
break;
}
// get element content
$end = strpos($html, '>', $cpos);
$len = $end - $p + 1;
$element = substr($html, $p, $len);
// move element to the end of the last li
$html = substr_replace($html, '', $p, $len);
$html = substr_replace($html, $element, $li_pos, 0);
$p = $end;
}
else {
$p++;
}
}
}
}
}
}
|