Skip to content
This repository

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Octocat-spinner-32-eaf2f5

Cannot retrieve contributors at this time

file 331 lines (296 sloc) 13.087 kb
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
<?php
/* 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.
*/

/* Please send me your comments about this code if you have some, thanks, Fred. */

/* 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.
*
* BUGS: It MUST be safe !
* - Check regexp
* - urlencode URLs instead of htmlspecials
* - Check is a 3 bytes utf8 first char can eat '">'
* - Update PCRE: CVE-2007-1659 - CVE-2007-1660 - CVE-2007-1661 - CVE-2007-1662
* CVE-2007-4766 - CVE-2007-4767 - CVE-2007-4768
* http://lists.debian.org/debian-security-announce/debian-security-announce-2007/msg00177.html
* - ...
*
* MISSING:
* - relative links, can be implemented by prefixing an absolute path, ask me
* if you need it...
* - ...
*
* Dont be a fool:
* - Dont alter data on a GET: '<img src="http://yourhost/mail?action=delete&uid=3267" />'
* - ...
*
* 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
*/

class 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',
    // attributes of form elements
    'type', 'rows', 'cols', 'disabled', 'readonly', 'checked', 'multiple', 'value'
  );

  /* Block elements which could be empty but cannot be returned in short form (<tag />) */
  static $block_elements = array('div', 'p', 'pre', 'blockquote', 'a', 'font', 'center',
    'table', 'ul', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'ol', 'dl', 'strong', 'i', 'b', 'u', 'span');

  /* 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();

  /* Block elements which could be empty but cannot be returned in short form (<tag />) */
  private $_block_elements = array();

  /* Allowed HTML attributes */
  private $_html_attribs = array();


  /* 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);
    $this->_block_elements = array_flip((array)$p['block_elements']) + array_flip(self::$block_elements);
    unset($p['html_elements'], $p['html_attribs'], $p['ignore_elements'], $p['block_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' && !preg_match('!^javascript!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 */
  private function dumpHtml($node)
  {
    if(!$node->hasChildNodes())
      return '';

    $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), $this);
        }
        else if (isset($this->_html_elements[$tagName])) {
          $content = $this->dumpHtml($node);
          $dump .= '<' . $tagName . $this->wash_attribs($node) .
            ($content != '' || isset($this->_block_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); // 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);
        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;

    // 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'] = '';

    // Remove invalid HTML comments (#1487759)
    // Don't remove valid conditional comments
    $html = preg_replace('/<!--[^->[\n]*>/', '', $html);

    @$node->loadHTML($html);
    return $this->dumpHtml($node);
  }

  /**
* Getter for config parameters
*/
  public function get_config($prop)
  {
      return $this->config[$prop];
  }

}
Something went wrong with that request. Please try again.