Mercurial > genshi > genshi-test
view markup/filters.py @ 187:29a19af7d17a stable-0.2.x 0.2.0
Prepare [milestone:0.2] release.
author | cmlenz |
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date | Tue, 22 Aug 2006 15:28:35 +0000 |
parents | 41db0260ebb1 |
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# -*- coding: utf-8 -*- # # Copyright (C) 2006 Edgewall Software # All rights reserved. # # This software is licensed as described in the file COPYING, which # you should have received as part of this distribution. The terms # are also available at http://markup.edgewall.org/wiki/License. # # This software consists of voluntary contributions made by many # individuals. For the exact contribution history, see the revision # history and logs, available at http://markup.edgewall.org/log/. """Implementation of a number of stream filters.""" try: frozenset except NameError: from sets import ImmutableSet as frozenset import re from markup.core import Attrs, Namespace, stripentities from markup.core import END, END_NS, START, START_NS __all__ = ['HTMLSanitizer', 'IncludeFilter'] class HTMLSanitizer(object): """A filter that removes potentially dangerous HTML tags and attributes from the stream. """ _SAFE_TAGS = frozenset(['a', 'abbr', 'acronym', 'address', 'area', 'b', 'big', 'blockquote', 'br', 'button', 'caption', 'center', 'cite', 'code', 'col', 'colgroup', 'dd', 'del', 'dfn', 'dir', 'div', 'dl', 'dt', 'em', 'fieldset', 'font', 'form', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'hr', 'i', 'img', 'input', 'ins', 'kbd', 'label', 'legend', 'li', 'map', 'menu', 'ol', 'optgroup', 'option', 'p', 'pre', 'q', 's', 'samp', 'select', 'small', 'span', 'strike', 'strong', 'sub', 'sup', 'table', 'tbody', 'td', 'textarea', 'tfoot', 'th', 'thead', 'tr', 'tt', 'u', 'ul', 'var']) _SAFE_ATTRS = frozenset(['abbr', 'accept', 'accept-charset', 'accesskey', 'action', 'align', 'alt', 'axis', 'bgcolor', 'border', 'cellpadding', 'cellspacing', 'char', 'charoff', 'charset', 'checked', 'cite', 'class', 'clear', 'cols', 'colspan', 'color', 'compact', 'coords', 'datetime', 'dir', 'disabled', 'enctype', 'for', 'frame', 'headers', 'height', 'href', 'hreflang', 'hspace', 'id', 'ismap', 'label', 'lang', 'longdesc', 'maxlength', 'media', 'method', 'multiple', 'name', 'nohref', 'noshade', 'nowrap', 'prompt', 'readonly', 'rel', 'rev', 'rows', 'rowspan', 'rules', 'scope', 'selected', 'shape', 'size', 'span', 'src', 'start', 'style', 'summary', 'tabindex', 'target', 'title', 'type', 'usemap', 'valign', 'value', 'vspace', 'width']) _URI_ATTRS = frozenset(['action', 'background', 'dynsrc', 'href', 'lowsrc', 'src']) _SAFE_SCHEMES = frozenset(['file', 'ftp', 'http', 'https', 'mailto', None]) def __call__(self, stream, ctxt=None): waiting_for = None for kind, data, pos in stream: if kind is START: if waiting_for: continue tag, attrib = data if tag not in self._SAFE_TAGS: waiting_for = tag continue new_attrib = Attrs() for attr, value in attrib: value = stripentities(value) if attr not in self._SAFE_ATTRS: continue elif attr in self._URI_ATTRS: # Don't allow URI schemes such as "javascript:" if self._get_scheme(value) not in self._SAFE_SCHEMES: continue elif attr == 'style': # Remove dangerous CSS declarations from inline styles decls = [] for decl in filter(None, value.split(';')): is_evil = False if 'expression' in decl: is_evil = True for m in re.finditer(r'url\s*\(([^)]+)', decl): if self._get_scheme(m.group(1)) not in self._SAFE_SCHEMES: is_evil = True break if not is_evil: decls.append(decl.strip()) if not decls: continue value = '; '.join(decls) new_attrib.append((attr, value)) yield kind, (tag, new_attrib), pos elif kind is END: tag = data if waiting_for: if waiting_for == tag: waiting_for = None else: yield kind, data, pos else: if not waiting_for: yield kind, data, pos def _get_scheme(self, text): if ':' not in text: return None chars = [char for char in text.split(':', 1)[0] if char.isalnum()] return ''.join(chars).lower() class IncludeFilter(object): """Template filter providing (very) basic XInclude support (see http://www.w3.org/TR/xinclude/) in templates. """ NAMESPACE = Namespace('http://www.w3.org/2001/XInclude') def __init__(self, loader): """Initialize the filter. @param loader: the `TemplateLoader` to use for resolving references to external template files """ self.loader = loader def __call__(self, stream, ctxt=None): """Filter the stream, processing any XInclude directives it may contain. @param stream: the markup event stream to filter @param ctxt: the template context """ from markup.template import TemplateError, TemplateNotFound ns_prefixes = [] in_fallback = False include_href, fallback_stream = None, None namespace = self.NAMESPACE for kind, data, pos in stream: if kind is START and not in_fallback and data[0] in namespace: tag, attrib = data if tag.localname == 'include': include_href = attrib.get('href') elif tag.localname == 'fallback': in_fallback = True fallback_stream = [] elif kind is END and data in namespace: if data.localname == 'include': try: if not include_href: raise TemplateError('Include misses required ' 'attribute "href"') template = self.loader.load(include_href, relative_to=pos[0]) for event in template.generate(ctxt): yield event except TemplateNotFound: if fallback_stream is None: raise for event in fallback_stream: yield event include_href = None fallback_stream = None elif data.localname == 'fallback': in_fallback = False elif in_fallback: fallback_stream.append((kind, data, pos)) elif kind is START_NS and data[1] == namespace: ns_prefixes.append(data[0]) elif kind is END_NS and data in ns_prefixes: ns_prefixes.pop() else: yield kind, data, pos