Mercurial > genshi > genshi-test
annotate genshi/filters/html.py @ 820:1837f39efd6f experimental-inline
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| author | cmlenz |
|---|---|
| date | Wed, 11 Mar 2009 17:51:06 +0000 |
| parents | 0742f421caba |
| children | 09cc3627654c |
| rev | line source |
|---|---|
| 500 | 1 # -*- coding: utf-8 -*- |
| 2 # | |
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3 # Copyright (C) 2006-2008 Edgewall Software |
| 500 | 4 # All rights reserved. |
| 5 # | |
| 6 # This software is licensed as described in the file COPYING, which | |
| 7 # you should have received as part of this distribution. The terms | |
| 8 # are also available at http://genshi.edgewall.org/wiki/License. | |
| 9 # | |
| 10 # This software consists of voluntary contributions made by many | |
| 11 # individuals. For the exact contribution history, see the revision | |
| 12 # history and logs, available at http://genshi.edgewall.org/log/. | |
| 13 | |
| 14 """Implementation of a number of stream filters.""" | |
| 15 | |
| 16 import re | |
| 17 | |
| 18 from genshi.core import Attrs, QName, stripentities | |
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19 from genshi.core import END, START, TEXT, COMMENT |
| 500 | 20 |
| 21 __all__ = ['HTMLFormFiller', 'HTMLSanitizer'] | |
| 22 __docformat__ = 'restructuredtext en' | |
| 23 | |
| 24 | |
| 25 class HTMLFormFiller(object): | |
| 26 """A stream filter that can populate HTML forms from a dictionary of values. | |
| 27 | |
| 28 >>> from genshi.input import HTML | |
| 29 >>> html = HTML('''<form> | |
| 30 ... <p><input type="text" name="foo" /></p> | |
| 31 ... </form>''') | |
| 32 >>> filler = HTMLFormFiller(data={'foo': 'bar'}) | |
| 33 >>> print html | filler | |
| 34 <form> | |
| 35 <p><input type="text" name="foo" value="bar"/></p> | |
| 36 </form> | |
| 37 """ | |
| 38 # TODO: only select the first radio button, and the first select option | |
| 39 # (if not in a multiple-select) | |
| 40 # TODO: only apply to elements in the XHTML namespace (or no namespace)? | |
| 41 | |
| 42 def __init__(self, name=None, id=None, data=None): | |
| 43 """Create the filter. | |
| 44 | |
| 45 :param name: The name of the form that should be populated. If this | |
| 46 parameter is given, only forms where the ``name`` attribute | |
| 47 value matches the parameter are processed. | |
| 48 :param id: The ID of the form that should be populated. If this | |
| 49 parameter is given, only forms where the ``id`` attribute | |
| 50 value matches the parameter are processed. | |
| 51 :param data: The dictionary of form values, where the keys are the names | |
| 52 of the form fields, and the values are the values to fill | |
| 53 in. | |
| 54 """ | |
| 55 self.name = name | |
| 56 self.id = id | |
| 57 if data is None: | |
| 58 data = {} | |
| 59 self.data = data | |
| 60 | |
| 61 def __call__(self, stream): | |
| 62 """Apply the filter to the given stream. | |
| 63 | |
| 64 :param stream: the markup event stream to filter | |
| 65 """ | |
| 66 in_form = in_select = in_option = in_textarea = False | |
| 67 select_value = option_value = textarea_value = None | |
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68 option_start = None |
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69 option_text = [] |
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70 no_option_value = False |
| 500 | 71 |
| 72 for kind, data, pos in stream: | |
| 73 | |
| 74 if kind is START: | |
| 75 tag, attrs = data | |
| 76 tagname = tag.localname | |
| 77 | |
| 78 if tagname == 'form' and ( | |
| 79 self.name and attrs.get('name') == self.name or | |
| 80 self.id and attrs.get('id') == self.id or | |
| 81 not (self.id or self.name)): | |
| 82 in_form = True | |
| 83 | |
| 84 elif in_form: | |
| 85 if tagname == 'input': | |
| 86 type = attrs.get('type') | |
| 87 if type in ('checkbox', 'radio'): | |
| 88 name = attrs.get('name') | |
| 89 if name and name in self.data: | |
| 90 value = self.data[name] | |
| 91 declval = attrs.get('value') | |
| 92 checked = False | |
| 93 if isinstance(value, (list, tuple)): | |
| 94 if declval: | |
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95 checked = declval in [unicode(v) for v |
| 500 | 96 in value] |
| 97 else: | |
| 98 checked = bool(filter(None, value)) | |
| 99 else: | |
| 100 if declval: | |
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101 checked = declval == unicode(value) |
| 500 | 102 elif type == 'checkbox': |
| 103 checked = bool(value) | |
| 104 if checked: | |
| 105 attrs |= [(QName('checked'), 'checked')] | |
| 106 elif 'checked' in attrs: | |
| 107 attrs -= 'checked' | |
| 108 elif type in (None, 'hidden', 'text'): | |
| 109 name = attrs.get('name') | |
| 110 if name and name in self.data: | |
| 111 value = self.data[name] | |
| 112 if isinstance(value, (list, tuple)): | |
| 113 value = value[0] | |
| 114 if value is not None: | |
| 115 attrs |= [(QName('value'), unicode(value))] | |
| 116 elif tagname == 'select': | |
| 117 name = attrs.get('name') | |
| 118 if name in self.data: | |
| 119 select_value = self.data[name] | |
| 120 in_select = True | |
| 121 elif tagname == 'textarea': | |
| 122 name = attrs.get('name') | |
| 123 if name in self.data: | |
| 124 textarea_value = self.data.get(name) | |
| 125 if isinstance(textarea_value, (list, tuple)): | |
| 126 textarea_value = textarea_value[0] | |
| 127 in_textarea = True | |
| 128 elif in_select and tagname == 'option': | |
| 129 option_start = kind, data, pos | |
| 130 option_value = attrs.get('value') | |
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131 if option_value is None: |
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132 no_option_value = True |
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133 option_value = '' |
| 500 | 134 in_option = True |
| 135 continue | |
| 136 yield kind, (tag, attrs), pos | |
| 137 | |
| 138 elif in_form and kind is TEXT: | |
| 139 if in_select and in_option: | |
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140 if no_option_value: |
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141 option_value += data |
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142 option_text.append((kind, data, pos)) |
| 500 | 143 continue |
| 144 elif in_textarea: | |
| 145 continue | |
| 146 yield kind, data, pos | |
| 147 | |
| 148 elif in_form and kind is END: | |
| 149 tagname = data.localname | |
| 150 if tagname == 'form': | |
| 151 in_form = False | |
| 152 elif tagname == 'select': | |
| 153 in_select = False | |
| 154 select_value = None | |
| 155 elif in_select and tagname == 'option': | |
| 156 if isinstance(select_value, (tuple, list)): | |
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157 selected = option_value in [unicode(v) for v |
| 500 | 158 in select_value] |
| 159 else: | |
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160 selected = option_value == unicode(select_value) |
| 500 | 161 okind, (tag, attrs), opos = option_start |
| 162 if selected: | |
| 163 attrs |= [(QName('selected'), 'selected')] | |
| 164 elif 'selected' in attrs: | |
| 165 attrs -= 'selected' | |
| 166 yield okind, (tag, attrs), opos | |
| 167 if option_text: | |
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168 for event in option_text: |
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169 yield event |
| 500 | 170 in_option = False |
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171 no_option_value = False |
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172 option_start = option_value = None |
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173 option_text = [] |
| 500 | 174 elif tagname == 'textarea': |
| 175 if textarea_value: | |
| 176 yield TEXT, unicode(textarea_value), pos | |
| 177 in_textarea = False | |
| 178 yield kind, data, pos | |
| 179 | |
| 180 else: | |
| 181 yield kind, data, pos | |
| 182 | |
| 183 | |
| 184 class HTMLSanitizer(object): | |
| 185 """A filter that removes potentially dangerous HTML tags and attributes | |
| 186 from the stream. | |
| 187 | |
| 188 >>> from genshi import HTML | |
| 189 >>> html = HTML('<div><script>alert(document.cookie)</script></div>') | |
| 190 >>> print html | HTMLSanitizer() | |
| 191 <div/> | |
| 192 | |
| 193 The default set of safe tags and attributes can be modified when the filter | |
| 194 is instantiated. For example, to allow inline ``style`` attributes, the | |
| 195 following instantation would work: | |
| 196 | |
| 197 >>> html = HTML('<div style="background: #000"></div>') | |
| 198 >>> sanitizer = HTMLSanitizer(safe_attrs=HTMLSanitizer.SAFE_ATTRS | set(['style'])) | |
| 199 >>> print html | sanitizer | |
| 200 <div style="background: #000"/> | |
| 201 | |
| 202 Note that even in this case, the filter *does* attempt to remove dangerous | |
| 203 constructs from style attributes: | |
| 204 | |
| 205 >>> html = HTML('<div style="background: url(javascript:void); color: #000"></div>') | |
| 206 >>> print html | sanitizer | |
| 207 <div style="color: #000"/> | |
| 208 | |
| 209 This handles HTML entities, unicode escapes in CSS and Javascript text, as | |
| 210 well as a lot of other things. However, the style tag is still excluded by | |
| 211 default because it is very hard for such sanitizing to be completely safe, | |
| 212 especially considering how much error recovery current web browsers perform. | |
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213 |
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214 :warn: Note that this special processing of CSS is currently only applied to |
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215 style attributes, **not** style elements. |
| 500 | 216 """ |
| 217 | |
| 218 SAFE_TAGS = frozenset(['a', 'abbr', 'acronym', 'address', 'area', 'b', | |
| 219 'big', 'blockquote', 'br', 'button', 'caption', 'center', 'cite', | |
| 220 'code', 'col', 'colgroup', 'dd', 'del', 'dfn', 'dir', 'div', 'dl', 'dt', | |
| 221 'em', 'fieldset', 'font', 'form', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', | |
| 222 'hr', 'i', 'img', 'input', 'ins', 'kbd', 'label', 'legend', 'li', 'map', | |
| 223 'menu', 'ol', 'optgroup', 'option', 'p', 'pre', 'q', 's', 'samp', | |
| 224 'select', 'small', 'span', 'strike', 'strong', 'sub', 'sup', 'table', | |
| 225 'tbody', 'td', 'textarea', 'tfoot', 'th', 'thead', 'tr', 'tt', 'u', | |
| 226 'ul', 'var']) | |
| 227 | |
| 228 SAFE_ATTRS = frozenset(['abbr', 'accept', 'accept-charset', 'accesskey', | |
| 229 'action', 'align', 'alt', 'axis', 'bgcolor', 'border', 'cellpadding', | |
| 230 'cellspacing', 'char', 'charoff', 'charset', 'checked', 'cite', 'class', | |
| 231 'clear', 'cols', 'colspan', 'color', 'compact', 'coords', 'datetime', | |
| 232 'dir', 'disabled', 'enctype', 'for', 'frame', 'headers', 'height', | |
| 233 'href', 'hreflang', 'hspace', 'id', 'ismap', 'label', 'lang', | |
| 234 'longdesc', 'maxlength', 'media', 'method', 'multiple', 'name', | |
| 235 'nohref', 'noshade', 'nowrap', 'prompt', 'readonly', 'rel', 'rev', | |
| 236 'rows', 'rowspan', 'rules', 'scope', 'selected', 'shape', 'size', | |
| 237 'span', 'src', 'start', 'summary', 'tabindex', 'target', 'title', | |
| 238 'type', 'usemap', 'valign', 'value', 'vspace', 'width']) | |
| 239 | |
| 240 SAFE_SCHEMES = frozenset(['file', 'ftp', 'http', 'https', 'mailto', None]) | |
| 241 | |
| 242 URI_ATTRS = frozenset(['action', 'background', 'dynsrc', 'href', 'lowsrc', | |
| 243 'src']) | |
| 244 | |
| 245 def __init__(self, safe_tags=SAFE_TAGS, safe_attrs=SAFE_ATTRS, | |
| 246 safe_schemes=SAFE_SCHEMES, uri_attrs=URI_ATTRS): | |
| 247 """Create the sanitizer. | |
| 248 | |
| 249 The exact set of allowed elements and attributes can be configured. | |
| 250 | |
| 251 :param safe_tags: a set of tag names that are considered safe | |
| 252 :param safe_attrs: a set of attribute names that are considered safe | |
| 253 :param safe_schemes: a set of URI schemes that are considered safe | |
| 254 :param uri_attrs: a set of names of attributes that contain URIs | |
| 255 """ | |
| 256 self.safe_tags = safe_tags | |
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257 "The set of tag names that are considered safe." |
| 500 | 258 self.safe_attrs = safe_attrs |
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259 "The set of attribute names that are considered safe." |
| 500 | 260 self.uri_attrs = uri_attrs |
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261 "The set of names of attributes that may contain URIs." |
| 500 | 262 self.safe_schemes = safe_schemes |
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263 "The set of URI schemes that are considered safe." |
| 500 | 264 |
| 265 def __call__(self, stream): | |
| 266 """Apply the filter to the given stream. | |
| 267 | |
| 268 :param stream: the markup event stream to filter | |
| 269 """ | |
| 270 waiting_for = None | |
| 271 | |
| 272 for kind, data, pos in stream: | |
| 273 if kind is START: | |
| 274 if waiting_for: | |
| 275 continue | |
| 276 tag, attrs = data | |
| 277 if tag not in self.safe_tags: | |
| 278 waiting_for = tag | |
| 279 continue | |
| 280 | |
| 281 new_attrs = [] | |
| 282 for attr, value in attrs: | |
| 283 value = stripentities(value) | |
| 284 if attr not in self.safe_attrs: | |
| 285 continue | |
| 286 elif attr in self.uri_attrs: | |
| 287 # Don't allow URI schemes such as "javascript:" | |
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288 if not self.is_safe_uri(value): |
| 500 | 289 continue |
| 290 elif attr == 'style': | |
| 291 # Remove dangerous CSS declarations from inline styles | |
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292 decls = self.sanitize_css(value) |
| 500 | 293 if not decls: |
| 294 continue | |
| 295 value = '; '.join(decls) | |
| 296 new_attrs.append((attr, value)) | |
| 297 | |
| 298 yield kind, (tag, Attrs(new_attrs)), pos | |
| 299 | |
| 300 elif kind is END: | |
| 301 tag = data | |
| 302 if waiting_for: | |
| 303 if waiting_for == tag: | |
| 304 waiting_for = None | |
| 305 else: | |
| 306 yield kind, data, pos | |
| 307 | |
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308 elif kind is not COMMENT: |
| 500 | 309 if not waiting_for: |
| 310 yield kind, data, pos | |
| 311 | |
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312 def is_safe_uri(self, uri): |
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313 """Determine whether the given URI is to be considered safe for |
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314 inclusion in the output. |
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315 |
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316 The default implementation checks whether the scheme of the URI is in |
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317 the set of allowed URIs (`safe_schemes`). |
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318 |
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319 >>> sanitizer = HTMLSanitizer() |
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320 >>> sanitizer.is_safe_uri('http://example.org/') |
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321 True |
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322 >>> sanitizer.is_safe_uri('javascript:alert(document.cookie)') |
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323 False |
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324 |
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325 :param uri: the URI to check |
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326 :return: `True` if the URI can be considered safe, `False` otherwise |
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327 :rtype: `bool` |
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328 :since: version 0.4.3 |
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329 """ |
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330 if ':' not in uri: |
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331 return True # This is a relative URI |
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332 chars = [char for char in uri.split(':', 1)[0] if char.isalnum()] |
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333 return ''.join(chars).lower() in self.safe_schemes |
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334 |
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335 def sanitize_css(self, text): |
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336 """Remove potentially dangerous property declarations from CSS code. |
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337 |
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338 In particular, properties using the CSS ``url()`` function with a scheme |
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339 that is not considered safe are removed: |
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340 |
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341 >>> sanitizer = HTMLSanitizer() |
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342 >>> sanitizer.sanitize_css(u''' |
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343 ... background: url(javascript:alert("foo")); |
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344 ... color: #000; |
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345 ... ''') |
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346 [u'color: #000'] |
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347 |
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348 Also, the proprietary Internet Explorer function ``expression()`` is |
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349 always stripped: |
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350 |
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351 >>> sanitizer.sanitize_css(u''' |
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352 ... background: #fff; |
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353 ... color: #000; |
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354 ... width: e/**/xpression(alert("foo")); |
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355 ... ''') |
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356 [u'background: #fff', u'color: #000'] |
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357 |
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358 :param text: the CSS text; this is expected to be `unicode` and to not |
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359 contain any character or numeric references |
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360 :return: a list of declarations that are considered safe |
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361 :rtype: `list` |
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362 :since: version 0.4.3 |
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363 """ |
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364 decls = [] |
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365 text = self._strip_css_comments(self._replace_unicode_escapes(text)) |
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366 for decl in filter(None, text.split(';')): |
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367 decl = decl.strip() |
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368 if not decl: |
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369 continue |
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370 is_evil = False |
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371 if 'expression' in decl: |
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372 is_evil = True |
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373 for match in re.finditer(r'url\s*\(([^)]+)', decl): |
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374 if not self.is_safe_uri(match.group(1)): |
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375 is_evil = True |
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376 break |
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377 if not is_evil: |
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378 decls.append(decl.strip()) |
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379 return decls |
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380 |
| 500 | 381 _NORMALIZE_NEWLINES = re.compile(r'\r\n').sub |
| 382 _UNICODE_ESCAPE = re.compile(r'\\([0-9a-fA-F]{1,6})\s?').sub | |
| 383 | |
| 384 def _replace_unicode_escapes(self, text): | |
| 385 def _repl(match): | |
| 386 return unichr(int(match.group(1), 16)) | |
| 387 return self._UNICODE_ESCAPE(_repl, self._NORMALIZE_NEWLINES('\n', text)) | |
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388 |
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389 _CSS_COMMENTS = re.compile(r'/\*.*?\*/').sub |
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390 |
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391 def _strip_css_comments(self, text): |
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392 return self._CSS_COMMENTS('', text) |