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- /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
- /* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is mozilla.org HTML Sanitizer code.
- *
- * The Initial Developer of the Original Code is
- * Ben Bucksch <mozilla@bucksch.org>.
- * Portions created by the Initial Developer are Copyright (C) 2002
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- * Netscape
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either of the GNU General Public License Version 2 or later (the "GPL"),
- * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
-
- /* Cleans up HTML source from unwanted tags/attributes
-
- This class implements a content sink, which takes a parsed HTML document
- and removes all tags and attributes that are not explicitly allowed.
-
- This may improve the viewing experience of the user and/or the
- security/privacy.
-
- What is allowed is defined by a string (format described before the
- implementation of |mozHTMLSanitizer::ParsePrefs()|). The sytnax of the
- definition is not very rich - you can only (dis)allow certain tags and
- attributes, but not where they may appear. (This makes the implementation
- much more simple.) E.g. it is impossible to disallow ordinary text as a
- direct child of the <head> node or to disallow multiple <head> nodes.
-
- We also remove some known bad attribute values like javascript: URLs.
- Draconian attitude.
-
- Currently, the output of this class is unparsed (!) HTML source, which
- means that each document has to go through the parser twice. Of course,
- that is a performance killer. There are some reasons for for me doing it
- that way:
- * There is, to my knowledge, no interface to hook up such modifiers
- in the document display data flow. We have a nice interface for doing
- the modifications (the DOM), but no place to get the DOM and to invoke
- this code. As I don't want to hack this directly into the html sink,
- I'd have to create a generic interface first, which is too much work for
- me at the moment.
- * It is quite easy to hook up modifiers for the (unparsed) data stream,
- both in netwerk (for the browser) and esp. in libmime (for Mailnews).
- * It seems like the safest method - it is easier to debug (you have the
- HTML source output to check) and is less prone to security-relevant bugs
- and regressions, because in the case of a bug, it will probably fall back
- to not outputting, which is safer than erring on the side of letting
- something slip through (most of the alternative approaches listed below
- are probably vulnerable to the latter).
- * It should be possible to later change this class to output a parsed HTML
- document.
- So, in other words, I had the choice between better design and better
- performance. I choose design. Bad performance has an effect on the users
- of this class only, while bad design has an effect on all users and
- programmers.
-
- That being said, I have some ideas, how do make it much more efficient, but
- they involve hacking core code.
- * At some point when we have DOM, but didn't do anything with it yet
- (in particular, didn't load any external objects or ran any javascript),
- walk the DOM and delete everything the user doesn't explicitly like.
- * There's this nice GetPref() in the HTMLContentSink. It isn't used exactly
- as I would like to, but that should be doable. Bascially, before
- processing any tag (e.g. in OpenContainer or AddLeaf), ask that
- function, if the tag is allowed. If not, just return.
- In any case, there's the problem, how the users of the renderer
- (e.g. Mailnews) can tell it to use the sanitizer and which tags are
- allowed (the browser may want to allow more tags than Mailnews).
- That probably means that I have to hack into the docshell (incl. its
- interface) or similar, which I would really like to avoid.
- Any ideas appreciated.
- */
- #ifndef _mozISanitizingSerializer_h__
- #define _mozISanitizingSerializer_h__
-
- #include "nsISupports.h"
- #include "nsAString.h"
-
- #define MOZ_SANITIZINGHTMLSERIALIZER_CONTRACTID "@mozilla.org/layout/htmlsanitizer;1"
-
- /* starting interface: nsIContentSerializer */
- #define MOZ_ISANITIZINGHTMLSERIALIZER_IID_STR "feca3c34-205e-4ae5-bd1c-03c686ff012b"
-
- #define MOZ_ISANITIZINGHTMLSERIALIZER_IID \
- {0xfeca3c34, 0x205e, 0x4ae5, \
- { 0xbd, 0x1c, 0x03, 0xc6, 0x86, 0xff, 0x01, 0x2b }}
-
- class mozISanitizingHTMLSerializer : public nsISupports {
- public:
-
- NS_DEFINE_STATIC_IID_ACCESSOR(MOZ_ISANITIZINGHTMLSERIALIZER_IID)
-
- NS_IMETHOD Initialize(nsAString* aOutString,
- PRUint32 aFlags,
- const nsAString& allowedTags) = 0;
- // This function violates string ownership rules, see impl.
- };
-
- #endif
-