mirror of https://github.com/zulip/zulip.git
146 lines
5.1 KiB
Python
146 lines
5.1 KiB
Python
import markdown
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import logging
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import traceback
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import urlparse
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import re
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from zephyr.lib.avatar import gravatar_hash
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from zephyr.lib.bugdown import codehilite, fenced_code
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class Gravatar(markdown.inlinepatterns.Pattern):
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def handleMatch(self, match):
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img = markdown.util.etree.Element('img')
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img.set('class', 'message_body_gravatar img-rounded')
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img.set('src', 'https://secure.gravatar.com/avatar/%s?d=identicon&s=30'
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% (gravatar_hash(match.group('email')),))
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return img
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class AutoLink(markdown.inlinepatterns.Pattern):
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def handleMatch(self, match):
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url = match.group('url')
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a = markdown.util.etree.Element('a')
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a.set('href', url)
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a.text = url
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return a
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class UListProcessor(markdown.blockprocessors.OListProcessor):
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""" Process unordered list blocks.
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Based on markdown.blockprocessors.UListProcessor, but does not accept
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'+' as a bullet character."""
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TAG = 'ul'
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RE = re.compile(r'^[ ]{0,3}[*-][ ]+(.*)')
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# Based on markdown.inlinepatterns.LinkPattern
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class LinkPattern(markdown.inlinepatterns.Pattern):
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""" Return a link element from the given match. """
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def handleMatch(self, m):
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el = markdown.util.etree.Element("a")
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el.text = m.group(2)
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href = m.group(9)
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if href:
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if href[0] == "<":
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href = href[1:-1]
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el.set("href", self.sanitize_url(self.unescape(href.strip())))
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else:
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el.set("href", "")
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return el
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def sanitize_url(self, url):
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"""
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Sanitize a url against xss attacks.
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See the docstring on markdown.inlinepatterns.LinkPattern.sanitize_url.
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"""
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try:
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parts = urlparse.urlparse(url.replace(' ', '%20'))
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scheme, netloc, path, params, query, fragment = parts
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except ValueError:
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# Bad url - so bad it couldn't be parsed.
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return ''
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# Humbug modification: If scheme is not specified, assume http://
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# It's unlikely that users want relative links within humbughq.com.
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# We re-enter sanitize_url because netloc etc. need to be re-parsed.
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if not scheme:
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return self.sanitize_url('http://' + url)
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locless_schemes = ['', 'mailto', 'news']
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if netloc == '' and scheme not in locless_schemes:
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# This fails regardless of anything else.
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# Return immediately to save additional proccessing
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return ''
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for part in parts[2:]:
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if ":" in part:
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# Not a safe url
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return ''
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# Url passes all tests. Return url as-is.
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return urlparse.urlunparse(parts)
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class Bugdown(markdown.Extension):
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def extendMarkdown(self, md, md_globals):
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for k in ('image_link', 'image_reference', 'automail', 'autolink', 'link'):
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del md.inlinePatterns[k]
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for k in ('hashheader', 'setextheader', 'olist', 'ulist'):
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del md.parser.blockprocessors[k]
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md.parser.blockprocessors.add('ulist', UListProcessor(md.parser), '>hr')
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md.inlinePatterns.add('gravatar', Gravatar(r'!gravatar\((?P<email>[^)]*)\)'), '_begin')
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md.inlinePatterns.add('link', LinkPattern(markdown.inlinepatterns.LINK_RE, md), '>reference')
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# A link starts at a word boundary, and ends at space or end-of-input.
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# But any trailing punctuation (other than /) is not included.
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# We accomplish this with a non-greedy match followed by a greedy
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# lookahead assertion.
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#
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# markdown.inlinepatterns.Pattern compiles this with re.UNICODE, which
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# is important because we're using \w.
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link_regex = r'\b(?P<url>https?://[^\s]+?)(?=[^\w/]*(\s|\Z))'
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md.inlinePatterns.add('autolink', AutoLink(link_regex), '>link')
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_md_engine = markdown.Markdown(
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safe_mode = 'escape',
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output_format = 'html',
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extensions = ['nl2br',
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codehilite.makeExtension(configs=[
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('force_linenos', False),
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('guess_lang', False)]),
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fenced_code.makeExtension(),
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Bugdown()])
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# We want to log Markdown parser failures, but shouldn't log the actual input
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# message for privacy reasons. The compromise is to replace all alphanumeric
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# characters with 'x'.
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#
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# We also use repr() to improve reproducibility, and to escape terminal control
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# codes, which can do surprisingly nasty things.
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_privacy_re = re.compile(r'\w', flags=re.UNICODE)
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def _sanitize_for_log(md):
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return repr(_privacy_re.sub('x', md))
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def _linkify(match):
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url = match.group('url')
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return ' [%s](%s) ' % (url, url)
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def convert(md):
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"""Convert Markdown to HTML, with Humbug-specific settings and hacks."""
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# Reset the parser; otherwise it will get slower over time.
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_md_engine.reset()
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try:
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html = _md_engine.convert(md)
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except:
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# FIXME: Do something more reasonable here!
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html = '<p>[Humbug note: Sorry, we could not understand the formatting of your message]</p>'
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logging.getLogger('').error('Exception in Markdown parser: %sInput (sanitized) was: %s'
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% (traceback.format_exc(), _sanitize_for_log(md)))
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return html
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