LCOV - app.info - objdir/dist/include/mozISanitizingSerializer.h

LCOV - code coverage report
| Current view: | directory - objdir/dist/include - mozISanitizingSerializer.h (source / functions) |  | Found | Hit | Coverage |
| Test: | app.info | Lines: | 1 | 0 | 0.0 %
| Date: | 2012-07-07 | Functions: | 1 | 0 | 0.0 %

           1                 : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
           2                 : /* ***** BEGIN LICENSE BLOCK *****
           3                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
           4                 :  *
           5                 :  * The contents of this file are subject to the Mozilla Public License Version
           6                 :  * 1.1 (the "License"); you may not use this file except in compliance with
           7                 :  * the License. You may obtain a copy of the License at
           8                 :  * http://www.mozilla.org/MPL/
           9                 :  *
          10                 :  * Software distributed under the License is distributed on an "AS IS" basis,
          11                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
          12                 :  * for the specific language governing rights and limitations under the
          13                 :  * License.
          14                 :  *
          15                 :  * The Original Code is mozilla.org HTML Sanitizer code.
          16                 :  *
          17                 :  * The Initial Developer of the Original Code is
          18                 :  * Ben Bucksch <mozilla@bucksch.org>.
          19                 :  * Portions created by the Initial Developer are Copyright (C) 2002
          20                 :  * the Initial Developer. All Rights Reserved.
          21                 :  *
          22                 :  * Contributor(s):
          23                 :  *   Netscape
          24                 :  *
          25                 :  * Alternatively, the contents of this file may be used under the terms of
          26                 :  * either of the GNU General Public License Version 2 or later (the "GPL"),
          27                 :  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
          28                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
          29                 :  * of those above. If you wish to allow use of your version of this file only
          30                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
          31                 :  * use your version of this file under the terms of the MPL, indicate your
          32                 :  * decision by deleting the provisions above and replace them with the notice
          33                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
          34                 :  * the provisions above, a recipient may use your version of this file under
          35                 :  * the terms of any one of the MPL, the GPL or the LGPL.
          36                 :  *
          37                 :  * ***** END LICENSE BLOCK ***** */
          38                 :
          39                 : /* Cleans up HTML source from unwanted tags/attributes
          40                 :
          41                 :    This class implements a content sink, which takes a parsed HTML document
          42                 :    and removes all tags and attributes that are not explicitly allowed.
          43                 :
          44                 :    This may improve the viewing experience of the user and/or the
          45                 :    security/privacy.
          46                 :
          47                 :    What is allowed is defined by a string (format described before the
          48                 :    implementation of |mozHTMLSanitizer::ParsePrefs()|). The sytnax of the
          49                 :    definition is not very rich - you can only (dis)allow certain tags and
          50                 :    attributes, but not where they may appear. (This makes the implementation
          51                 :    much more simple.) E.g. it is impossible to disallow ordinary text as a
          52                 :    direct child of the <head> node or to disallow multiple <head> nodes.
          53                 :
          54                 :    We also remove some known bad attribute values like javascript: URLs.
          55                 :    Draconian attitude.
          56                 :
          57                 :    Currently, the output of this class is unparsed (!) HTML source, which
          58                 :    means that each document has to go through the parser twice. Of course,
          59                 :    that is a performance killer. There are some reasons for for me doing it
          60                 :    that way:
          61                 :    * There is, to my knowledge, no interface to hook up such modifiers
          62                 :      in the document display data flow. We have a nice interface for doing
          63                 :      the modifications (the DOM), but no place to get the DOM and to invoke
          64                 :      this code. As I don't want to hack this directly into the html sink,
          65                 :      I'd have to create a generic interface first, which is too much work for
          66                 :      me at the moment.
          67                 :    * It is quite easy to hook up modifiers for the (unparsed) data stream,
          68                 :      both in netwerk (for the browser) and esp. in libmime (for Mailnews).
          69                 :    * It seems like the safest method - it is easier to debug (you have the
          70                 :      HTML source output to check) and is less prone to security-relevant bugs
          71                 :      and regressions, because in the case of a bug, it will probably fall back
          72                 :      to not outputting, which is safer than erring on the side of letting
          73                 :      something slip through (most of the alternative approaches listed below
          74                 :      are probably vulnerable to the latter).
          75                 :    * It should be possible to later change this class to output a parsed HTML
          76                 :      document.
          77                 :    So, in other words, I had the choice between better design and better
          78                 :    performance. I choose design. Bad performance has an effect on the users
          79                 :    of this class only, while bad design has an effect on all users and
          80                 :    programmers.
          81                 :
          82                 :    That being said, I have some ideas, how do make it much more efficient, but
          83                 :    they involve hacking core code.
          84                 :    * At some point when we have DOM, but didn't do anything with it yet
          85                 :      (in particular, didn't load any external objects or ran any javascript),
          86                 :      walk the DOM and delete everything the user doesn't explicitly like.
          87                 :    * There's this nice GetPref() in the HTMLContentSink. It isn't used exactly
          88                 :      as I would like to, but that should be doable. Bascially, before
          89                 :      processing any tag (e.g. in OpenContainer or AddLeaf), ask that
          90                 :      function, if the tag is allowed. If not, just return.
          91                 :    In any case, there's the problem, how the users of the renderer
          92                 :    (e.g. Mailnews) can tell it to use the sanitizer and which tags are
          93                 :    allowed (the browser may want to allow more tags than Mailnews).
          94                 :    That probably means that I have to hack into the docshell (incl. its
          95                 :    interface) or similar, which I would really like to avoid.
          96                 :    Any ideas appreciated.
          97                 : */
          98                 : #ifndef _mozISanitizingSerializer_h__
          99                 : #define _mozISanitizingSerializer_h__
         100                 :
         101                 : #include "nsISupports.h"
         102                 :
         103                 : class nsAString;
         104                 :
         105                 : #define MOZ_SANITIZINGHTMLSERIALIZER_CONTRACTID "@mozilla.org/layout/htmlsanitizer;1"
         106                 :
         107                 : /* starting interface:    nsIContentSerializer */
         108                 : #define MOZ_ISANITIZINGHTMLSERIALIZER_IID_STR "feca3c34-205e-4ae5-bd1c-03c686ff012b"
         109                 :
         110                 : #define MOZ_ISANITIZINGHTMLSERIALIZER_IID \
         111                 :   {0xfeca3c34, 0x205e, 0x4ae5, \
         112                 :     { 0xbd, 0x1c, 0x03, 0xc6, 0x86, 0xff, 0x01, 0x2b }}
         113                 :
         114               0 : class mozISanitizingHTMLSerializer : public nsISupports {
         115                 :  public:
         116                 :
         117                 :   NS_DECLARE_STATIC_IID_ACCESSOR(MOZ_ISANITIZINGHTMLSERIALIZER_IID)
         118                 :
         119                 :   NS_IMETHOD Initialize(nsAString* aOutString,
         120                 :                         PRUint32 aFlags,
         121                 :                         const nsAString& allowedTags) = 0;
         122                 :   // This function violates string ownership rules, see impl.
         123                 : };
         124                 :
         125                 : NS_DEFINE_STATIC_IID_ACCESSOR(mozISanitizingHTMLSerializer,
         126                 :                               MOZ_ISANITIZINGHTMLSERIALIZER_IID)
         127                 :
         128                 : #endif

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