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Filename :
sanitizer.py
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from __future__ import absolute_import, division, unicode_literals import re from xml.sax.saxutils import escape, unescape from .tokenizer import HTMLTokenizer from .constants import tokenTypes class HTMLSanitizerMixin(object): """ sanitization of XHTML+MathML+SVG and of inline style attributes.""" acceptable_elements = ['a', 'abbr', 'acronym', 'address', 'area', 'article', 'aside', 'audio', 'b', 'big', 'blockquote', 'br', 'button', 'canvas', 'caption', 'center', 'cite', 'code', 'col', 'colgroup', 'command', 'datagrid', 'datalist', 'dd', 'del', 'details', 'dfn', 'dialog', 'dir', 'div', 'dl', 'dt', 'em', 'event-source', 'fieldset', 'figcaption', 'figure', 'footer', 'font', 'form', 'header', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'hr', 'i', 'img', 'input', 'ins', 'keygen', 'kbd', 'label', 'legend', 'li', 'm', 'map', 'menu', 'meter', 'multicol', 'nav', 'nextid', 'ol', 'output', 'optgroup', 'option', 'p', 'pre', 'progress', 'q', 's', 'samp', 'section', 'select', 'small', 'sound', 'source', 'spacer', 'span', 'strike', 'strong', 'sub', 'sup', 'table', 'tbody', 'td', 'textarea', 'time', 'tfoot', 'th', 'thead', 'tr', 'tt', 'u', 'ul', 'var', 'video'] mathml_elements = ['maction', 'math', 'merror', 'mfrac', 'mi', 'mmultiscripts', 'mn', 'mo', 'mover', 'mpadded', 'mphantom', 'mprescripts', 'mroot', 'mrow', 'mspace', 'msqrt', 'mstyle', 'msub', 'msubsup', 'msup', 'mtable', 'mtd', 'mtext', 'mtr', 'munder', 'munderover', 'none'] svg_elements = ['a', 'animate', 'animateColor', 'animateMotion', 'animateTransform', 'clipPath', 'circle', 'defs', 'desc', 'ellipse', 'font-face', 'font-face-name', 'font-face-src', 'g', 'glyph', 'hkern', 'linearGradient', 'line', 'marker', 'metadata', 'missing-glyph', 'mpath', 'path', 'polygon', 'polyline', 'radialGradient', 'rect', 'set', 'stop', 'svg', 'switch', 'text', 'title', 'tspan', 'use'] acceptable_attributes = ['abbr', 'accept', 'accept-charset', 'accesskey', 'action', 'align', 'alt', 'autocomplete', 'autofocus', 'axis', 'background', 'balance', 'bgcolor', 'bgproperties', 'border', 'bordercolor', 'bordercolordark', 'bordercolorlight', 'bottompadding', 'cellpadding', 'cellspacing', 'ch', 'challenge', 'char', 'charoff', 'choff', 'charset', 'checked', 'cite', 'class', 'clear', 'color', 'cols', 'colspan', 'compact', 'contenteditable', 'controls', 'coords', 'data', 'datafld', 'datapagesize', 'datasrc', 'datetime', 'default', 'delay', 'dir', 'disabled', 'draggable', 'dynsrc', 'enctype', 'end', 'face', 'for', 'form', 'frame', 'galleryimg', 'gutter', 'headers', 'height', 'hidefocus', 'hidden', 'high', 'href', 'hreflang', 'hspace', 'icon', 'id', 'inputmode', 'ismap', 'keytype', 'label', 'leftspacing', 'lang', 'list', 'longdesc', 'loop', 'loopcount', 'loopend', 'loopstart', 'low', 'lowsrc', 'max', 'maxlength', 'media', 'method', 'min', 'multiple', 'name', 'nohref', 'noshade', 'nowrap', 'open', 'optimum', 'pattern', 'ping', 'point-size', 'poster', 'pqg', 'preload', 'prompt', 'radiogroup', 'readonly', 'rel', 'repeat-max', 'repeat-min', 'replace', 'required', 'rev', 'rightspacing', 'rows', 'rowspan', 'rules', 'scope', 'selected', 'shape', 'size', 'span', 'src', 'start', 'step', 'style', 'summary', 'suppress', 'tabindex', 'target', 'template', 'title', 'toppadding', 'type', 'unselectable', 'usemap', 'urn', 'valign', 'value', 'variable', 'volume', 'vspace', 'vrml', 'width', 'wrap', 'xml:lang'] mathml_attributes = ['actiontype', 'align', 'columnalign', 'columnalign', 'columnalign', 'columnlines', 'columnspacing', 'columnspan', 'depth', 'display', 'displaystyle', 'equalcolumns', 'equalrows', 'fence', 'fontstyle', 'fontweight', 'frame', 'height', 'linethickness', 'lspace', 'mathbackground', 'mathcolor', 'mathvariant', 'mathvariant', 'maxsize', 'minsize', 'other', 'rowalign', 'rowalign', 'rowalign', 'rowlines', 'rowspacing', 'rowspan', 'rspace', 'scriptlevel', 'selection', 'separator', 'stretchy', 'width', 'width', 'xlink:href', 'xlink:show', 'xlink:type', 'xmlns', 'xmlns:xlink'] svg_attributes = ['accent-height', 'accumulate', 'additive', 'alphabetic', 'arabic-form', 'ascent', 'attributeName', 'attributeType', 'baseProfile', 'bbox', 'begin', 'by', 'calcMode', 'cap-height', 'class', 'clip-path', 'color', 'color-rendering', 'content', 'cx', 'cy', 'd', 'dx', 'dy', 'descent', 'display', 'dur', 'end', 'fill', 'fill-opacity', 'fill-rule', 'font-family', 'font-size', 'font-stretch', 'font-style', 'font-variant', 'font-weight', 'from', 'fx', 'fy', 'g1', 'g2', 'glyph-name', 'gradientUnits', 'hanging', 'height', 'horiz-adv-x', 'horiz-origin-x', 'id', 'ideographic', 'k', 'keyPoints', 'keySplines', 'keyTimes', 'lang', 'marker-end', 'marker-mid', 'marker-start', 'markerHeight', 'markerUnits', 'markerWidth', 'mathematical', 'max', 'min', 'name', 'offset', 'opacity', 'orient', 'origin', 'overline-position', 'overline-thickness', 'panose-1', 'path', 'pathLength', 'points', 'preserveAspectRatio', 'r', 'refX', 'refY', 'repeatCount', 'repeatDur', 'requiredExtensions', 'requiredFeatures', 'restart', 'rotate', 'rx', 'ry', 'slope', 'stemh', 'stemv', 'stop-color', 'stop-opacity', 'strikethrough-position', 'strikethrough-thickness', 'stroke', 'stroke-dasharray', 'stroke-dashoffset', 'stroke-linecap', 'stroke-linejoin', 'stroke-miterlimit', 'stroke-opacity', 'stroke-width', 'systemLanguage', 'target', 'text-anchor', 'to', 'transform', 'type', 'u1', 'u2', 'underline-position', 'underline-thickness', 'unicode', 'unicode-range', 'units-per-em', 'values', 'version', 'viewBox', 'visibility', 'width', 'widths', 'x', 'x-height', 'x1', 'x2', 'xlink:actuate', 'xlink:arcrole', 'xlink:href', 'xlink:role', 'xlink:show', 'xlink:title', 'xlink:type', 'xml:base', 'xml:lang', 'xml:space', 'xmlns', 'xmlns:xlink', 'y', 'y1', 'y2', 'zoomAndPan'] attr_val_is_uri = ['href', 'src', 'cite', 'action', 'longdesc', 'poster', 'xlink:href', 'xml:base'] svg_attr_val_allows_ref = ['clip-path', 'color-profile', 'cursor', 'fill', 'filter', 'marker', 'marker-start', 'marker-mid', 'marker-end', 'mask', 'stroke'] svg_allow_local_href = ['altGlyph', 'animate', 'animateColor', 'animateMotion', 'animateTransform', 'cursor', 'feImage', 'filter', 'linearGradient', 'pattern', 'radialGradient', 'textpath', 'tref', 'set', 'use'] acceptable_css_properties = ['azimuth', 'background-color', 'border-bottom-color', 'border-collapse', 'border-color', 'border-left-color', 'border-right-color', 'border-top-color', 'clear', 'color', 'cursor', 'direction', 'display', 'elevation', 'float', 'font', 'font-family', 'font-size', 'font-style', 'font-variant', 'font-weight', 'height', 'letter-spacing', 'line-height', 'overflow', 'pause', 'pause-after', 'pause-before', 'pitch', 'pitch-range', 'richness', 'speak', 'speak-header', 'speak-numeral', 'speak-punctuation', 'speech-rate', 'stress', 'text-align', 'text-decoration', 'text-indent', 'unicode-bidi', 'vertical-align', 'voice-family', 'volume', 'white-space', 'width'] acceptable_css_keywords = ['auto', 'aqua', 'black', 'block', 'blue', 'bold', 'both', 'bottom', 'brown', 'center', 'collapse', 'dashed', 'dotted', 'fuchsia', 'gray', 'green', '!important', 'italic', 'left', 'lime', 'maroon', 'medium', 'none', 'navy', 'normal', 'nowrap', 'olive', 'pointer', 'purple', 'red', 'right', 'solid', 'silver', 'teal', 'top', 'transparent', 'underline', 'white', 'yellow'] acceptable_svg_properties = ['fill', 'fill-opacity', 'fill-rule', 'stroke', 'stroke-width', 'stroke-linecap', 'stroke-linejoin', 'stroke-opacity'] acceptable_protocols = ['ed2k', 'ftp', 'http', 'https', 'irc', 'mailto', 'news', 'gopher', 'nntp', 'telnet', 'webcal', 'xmpp', 'callto', 'feed', 'urn', 'aim', 'rsync', 'tag', 'ssh', 'sftp', 'rtsp', 'afs'] # subclasses may define their own versions of these constants allowed_elements = acceptable_elements + mathml_elements + svg_elements allowed_attributes = acceptable_attributes + mathml_attributes + svg_attributes allowed_css_properties = acceptable_css_properties allowed_css_keywords = acceptable_css_keywords allowed_svg_properties = acceptable_svg_properties allowed_protocols = acceptable_protocols # Sanitize the +html+, escaping all elements not in ALLOWED_ELEMENTS, and # stripping out all # attributes not in ALLOWED_ATTRIBUTES. Style # attributes are parsed, and a restricted set, # specified by # ALLOWED_CSS_PROPERTIES and ALLOWED_CSS_KEYWORDS, are allowed through. # attributes in ATTR_VAL_IS_URI are scanned, and only URI schemes specified # in ALLOWED_PROTOCOLS are allowed. # # sanitize_html('<script> do_nasty_stuff() </script>') # => <script> do_nasty_stuff() </script> # sanitize_html('<a href="javascript: sucker();">Click here for $100</a>') # => <a>Click here for $100</a> def sanitize_token(self, token): # accommodate filters which use token_type differently token_type = token["type"] if token_type in list(tokenTypes.keys()): token_type = tokenTypes[token_type] if token_type in (tokenTypes["StartTag"], tokenTypes["EndTag"], tokenTypes["EmptyTag"]): if token["name"] in self.allowed_elements: return self.allowed_token(token, token_type) else: return self.disallowed_token(token, token_type) elif token_type == tokenTypes["Comment"]: pass else: return token def allowed_token(self, token, token_type): if "data" in token: attrs = dict([(name, val) for name, val in token["data"][::-1] if name in self.allowed_attributes]) for attr in self.attr_val_is_uri: if attr not in attrs: continue val_unescaped = re.sub("[`\000-\040\177-\240\s]+", '', unescape(attrs[attr])).lower() # remove replacement characters from unescaped characters val_unescaped = val_unescaped.replace("\ufffd", "") if (re.match("^[a-z0-9][-+.a-z0-9]*:", val_unescaped) and (val_unescaped.split(':')[0] not in self.allowed_protocols)): del attrs[attr] for attr in self.svg_attr_val_allows_ref: if attr in attrs: attrs[attr] = re.sub(r'url\s*\(\s*[^#\s][^)]+?\)', ' ', unescape(attrs[attr])) if (token["name"] in self.svg_allow_local_href and 'xlink:href' in attrs and re.search('^\s*[^#\s].*', attrs['xlink:href'])): del attrs['xlink:href'] if 'style' in attrs: attrs['style'] = self.sanitize_css(attrs['style']) token["data"] = [[name, val] for name, val in list(attrs.items())] return token def disallowed_token(self, token, token_type): if token_type == tokenTypes["EndTag"]: token["data"] = "</%s>" % token["name"] elif token["data"]: attrs = ''.join([' %s="%s"' % (k, escape(v)) for k, v in token["data"]]) token["data"] = "<%s%s>" % (token["name"], attrs) else: token["data"] = "<%s>" % token["name"] if token.get("selfClosing"): token["data"] = token["data"][:-1] + "/>" if token["type"] in list(tokenTypes.keys()): token["type"] = "Characters" else: token["type"] = tokenTypes["Characters"] del token["name"] return token def sanitize_css(self, style): # disallow urls style = re.compile('url\s*\(\s*[^\s)]+?\s*\)\s*').sub(' ', style) # gauntlet if not re.match("""^([:,;#%.\sa-zA-Z0-9!]|\w-\w|'[\s\w]+'|"[\s\w]+"|\([\d,\s]+\))*$""", style): return '' if not re.match("^\s*([-\w]+\s*:[^:;]*(;\s*|$))*$", style): return '' clean = [] for prop, value in re.findall("([-\w]+)\s*:\s*([^:;]*)", style): if not value: continue if prop.lower() in self.allowed_css_properties: clean.append(prop + ': ' + value + ';') elif prop.split('-')[0].lower() in ['background', 'border', 'margin', 'padding']: for keyword in value.split(): if not keyword in self.acceptable_css_keywords and \ not re.match("^(#[0-9a-f]+|rgb\(\d+%?,\d*%?,?\d*%?\)?|\d{0,2}\.?\d{0,2}(cm|em|ex|in|mm|pc|pt|px|%|,|\))?)$", keyword): break else: clean.append(prop + ': ' + value + ';') elif prop.lower() in self.allowed_svg_properties: clean.append(prop + ': ' + value + ';') return ' '.join(clean) class HTMLSanitizer(HTMLTokenizer, HTMLSanitizerMixin): def __init__(self, stream, encoding=None, parseMeta=True, useChardet=True, lowercaseElementName=False, lowercaseAttrName=False, parser=None): # Change case matching defaults as we only output lowercase html anyway # This solution doesn't seem ideal... HTMLTokenizer.__init__(self, stream, encoding, parseMeta, useChardet, lowercaseElementName, lowercaseAttrName, parser=parser) def __iter__(self): for token in HTMLTokenizer.__iter__(self): token = self.sanitize_token(token) if token: yield token