Move washtml class into Roundcube Framework (rcube_washtml), add some improvements

1 files changed, 451 insertions, 0 deletions

diff --git a/program/lib/Roundcube/rcube_washtml.php b/program/lib/Roundcube/rcube_washtml.php
new file mode 100644
index 000000000..715c46047
--- /dev/null
+++ b/program/lib/Roundcube/rcube_washtml.php
@@ -0,0 +1,451 @@
+<?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'
+    );
+
+    /* 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 $_html_attribs = array();
+
+
+    /**
+     * Class constructor
+     */
+    public function __construct($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);
+        $this->_block_elements  = array_flip((array)$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|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
+     */
+    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;
+
+        $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 {
+            $this->config['base_url'] = '';
+        }
+
+        @$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'.' &nbsp; '.'\\3',
+            '',
+            '',
+            '<html>',
+        );
+        $html = preg_replace($html_search, $html_replace, trim($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
+        $html = preg_replace('/<!--[^->[\n]*>/', '', $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);
+
+        return $matches[1] . $tagname;
+    }
+
+    /**
+     * Convert all relative URLs according to a <base> in HTML
+     */
+    public static function resolve_base($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;
+    }
+}
+