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"""Subclass of HTMLParser.HTMLParser for MessageView widget"""
import inspect
import re
from HTMLParser import HTMLParser
from urllib import quote_plus
from urlparse import urlparse
class SafeHTMLParser(HTMLParser):
"""HTML parser with sanitisation"""
# from html5lib.sanitiser
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', 'header', 'h1',
'h2', 'h3', 'h4', 'h5', 'h6', 'hr', 'i', 'img', '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'
replaces_pre = (
("&", "&amp;"), ("\"", "&quot;"), ("<", "&lt;"), (">", "&gt;"))
replaces_post = (
("\n", "<br/>"), ("\t", "&nbsp;&nbsp;&nbsp;&nbsp;"),
(" ", "&nbsp; "), (" ", "&nbsp; "), ("<br/> ", "<br/>&nbsp;"))
src_schemes = ["data"]
# uriregex1 = re.compile(
# r'(?i)\b((?:(https?|ftp|bitcoin):(?:/{1,3}|[a-z0-9%])'
# r'|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}/)'
# r'(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))'
# r'+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:\'".,<>?]))')
uriregex1 = re.compile(
uriregex2 = re.compile(r'<a href="([^"]+)&amp;')
emailregex = re.compile(
def replace_pre(text):
"""Perform substring replacement before regex replacements"""
for a in SafeHTMLParser.replaces_pre:
text = text.replace(*a)
return text
def replace_post(text):
"""Perform substring replacement after regex replacements"""
for a in SafeHTMLParser.replaces_post:
text = text.replace(*a)
if len(text) > 1 and text[0] == " ":
text = "&nbsp;" + text[1:]
return text
def __init__(self, *args, **kwargs):
HTMLParser.__init__(self, *args, **kwargs)
def reset_safe(self):
"""Reset runtime variables specific to this class"""
self.elements = set()
self.raw = u""
self.sanitised = u""
self.has_html = False
self.allow_picture = False
self.allow_external_src = False
def add_if_acceptable(self, tag, attrs=None):
"""Add tag if it passes sanitisation"""
if tag not in self.acceptable_elements:
self.sanitised += "<"
if inspect.stack()[1][3] == "handle_endtag":
self.sanitised += "/"
self.sanitised += tag
if attrs is not None:
for attr, val in attrs:
if tag == "img" and attr == "src" and not self.allow_picture:
val = ""
elif attr == "src" and not self.allow_external_src:
url = urlparse(val)
if url.scheme not in self.src_schemes:
val = ""
self.sanitised += " " + quote_plus(attr)
if not (val is None):
self.sanitised += "=\"" + val + "\""
if inspect.stack()[1][3] == "handle_startendtag":
self.sanitised += "/"
self.sanitised += ">"
def handle_starttag(self, tag, attrs):
if tag in self.acceptable_elements:
self.has_html = True
self.add_if_acceptable(tag, attrs)
def handle_endtag(self, tag):
def handle_startendtag(self, tag, attrs):
if tag in self.acceptable_elements:
self.has_html = True
self.add_if_acceptable(tag, attrs)
def handle_data(self, data):
self.sanitised += data
def handle_charref(self, name):
self.sanitised += "&#" + name + ";"
def handle_entityref(self, name):
self.sanitised += "&" + name + ";"
def feed(self, data):
data = unicode(data, 'utf-8')
except UnicodeDecodeError:
data = unicode(data, 'utf-8', errors='replace')
HTMLParser.feed(self, data)
tmp = SafeHTMLParser.replace_pre(data)
tmp = self.uriregex1.sub(r'<a href="\1">\1</a>', tmp)
tmp = self.uriregex2.sub(r'<a href="\1&', tmp)
tmp = self.emailregex.sub(r'<a href="mailto:\1">\1</a>', tmp)
tmp = SafeHTMLParser.replace_post(tmp)
self.raw += tmp
def is_html(self, text=None, allow_picture=False):
"""Detect if string contains HTML tags"""
if text:
self.allow_picture = allow_picture
return self.has_html