python-feedgen/feedgen/ext/syndication.py
Lars Kiesow 0eb12f9133
Prevent XML Denial of Service Attacks
This patch prevents entity expansion for provided XML content to guard
against XML denial of service attacks like XML bomb or Billion laughs
attack.
2020-01-28 17:29:11 +01:00

60 lines
1.7 KiB
Python

# -*- coding: utf-8 -*-
#
# Copyright 2015 Kenichi Sato <ksato9700@gmail.com>
#
'''
Extends FeedGenerator to support Syndication module
See below for details
http://web.resource.org/rss/1.0/modules/syndication/
'''
from feedgen.ext.base import BaseExtension
from feedgen.util import xml_elem
SYNDICATION_NS = 'http://purl.org/rss/1.0/modules/syndication/'
PERIOD_TYPE = ('hourly', 'daily', 'weekly', 'monthly', 'yearly')
def _set_value(channel, name, value):
if value:
newelem = xml_elem('{%s}' % SYNDICATION_NS + name, channel)
newelem.text = value
class SyndicationExtension(BaseExtension):
def __init__(self):
self._update_period = None
self._update_freq = None
self._update_base = None
def extend_ns(self):
return {'sy': SYNDICATION_NS}
def extend_rss(self, rss_feed):
channel = rss_feed[0]
_set_value(channel, 'UpdatePeriod', self._update_period)
_set_value(channel, 'UpdateFrequency', str(self._update_freq))
_set_value(channel, 'UpdateBase', self._update_base)
def update_period(self, value):
if value not in PERIOD_TYPE:
raise ValueError('Invalid update period value')
self._update_period = value
return self._update_period
def update_frequency(self, value):
if type(value) is not int or value <= 0:
raise ValueError('Invalid update frequency value')
self._update_freq = value
return self._update_freq
def update_base(self, value):
# the value should be in W3CDTF format
self._update_base = value
return self._update_base
class SyndicationEntryExtension(BaseExtension):
pass