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154 lines
4.8 KiB
154 lines
4.8 KiB
# defusedxml
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#
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# Copyright (c) 2013 by Christian Heimes <christian@python.org>
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# Licensed to PSF under a Contributor Agreement.
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# See https://www.python.org/psf/license for licensing details.
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"""DEPRECATED Example code for lxml.etree protection
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The code has NO protection against decompression bombs.
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"""
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from __future__ import print_function, absolute_import
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import threading
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import warnings
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from lxml import etree as _etree
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from .common import DTDForbidden, EntitiesForbidden, NotSupportedError
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LXML3 = _etree.LXML_VERSION[0] >= 3
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__origin__ = "lxml.etree"
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tostring = _etree.tostring
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warnings.warn(
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"defusedxml.lxml is no longer supported and will be removed in a future release.",
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category=DeprecationWarning,
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stacklevel=2,
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)
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class RestrictedElement(_etree.ElementBase):
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"""A restricted Element class that filters out instances of some classes"""
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__slots__ = ()
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# blacklist = (etree._Entity, etree._ProcessingInstruction, etree._Comment)
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blacklist = _etree._Entity
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def _filter(self, iterator):
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blacklist = self.blacklist
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for child in iterator:
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if isinstance(child, blacklist):
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continue
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yield child
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def __iter__(self):
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iterator = super(RestrictedElement, self).__iter__()
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return self._filter(iterator)
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def iterchildren(self, tag=None, reversed=False):
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iterator = super(RestrictedElement, self).iterchildren(tag=tag, reversed=reversed)
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return self._filter(iterator)
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def iter(self, tag=None, *tags):
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iterator = super(RestrictedElement, self).iter(tag=tag, *tags)
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return self._filter(iterator)
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def iterdescendants(self, tag=None, *tags):
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iterator = super(RestrictedElement, self).iterdescendants(tag=tag, *tags)
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return self._filter(iterator)
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def itersiblings(self, tag=None, preceding=False):
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iterator = super(RestrictedElement, self).itersiblings(tag=tag, preceding=preceding)
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return self._filter(iterator)
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def getchildren(self):
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iterator = super(RestrictedElement, self).__iter__()
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return list(self._filter(iterator))
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def getiterator(self, tag=None):
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iterator = super(RestrictedElement, self).getiterator(tag)
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return self._filter(iterator)
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class GlobalParserTLS(threading.local):
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"""Thread local context for custom parser instances"""
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parser_config = {
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"resolve_entities": False,
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# 'remove_comments': True,
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# 'remove_pis': True,
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}
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element_class = RestrictedElement
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def createDefaultParser(self):
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parser = _etree.XMLParser(**self.parser_config)
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element_class = self.element_class
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if self.element_class is not None:
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lookup = _etree.ElementDefaultClassLookup(element=element_class)
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parser.set_element_class_lookup(lookup)
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return parser
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def setDefaultParser(self, parser):
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self._default_parser = parser
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def getDefaultParser(self):
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parser = getattr(self, "_default_parser", None)
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if parser is None:
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parser = self.createDefaultParser()
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self.setDefaultParser(parser)
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return parser
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_parser_tls = GlobalParserTLS()
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getDefaultParser = _parser_tls.getDefaultParser
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def check_docinfo(elementtree, forbid_dtd=False, forbid_entities=True):
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"""Check docinfo of an element tree for DTD and entity declarations
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The check for entity declarations needs lxml 3 or newer. lxml 2.x does
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not support dtd.iterentities().
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"""
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docinfo = elementtree.docinfo
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if docinfo.doctype:
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if forbid_dtd:
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raise DTDForbidden(docinfo.doctype, docinfo.system_url, docinfo.public_id)
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if forbid_entities and not LXML3:
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# lxml < 3 has no iterentities()
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raise NotSupportedError("Unable to check for entity declarations " "in lxml 2.x")
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if forbid_entities:
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for dtd in docinfo.internalDTD, docinfo.externalDTD:
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if dtd is None:
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continue
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for entity in dtd.iterentities():
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raise EntitiesForbidden(entity.name, entity.content, None, None, None, None)
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def parse(source, parser=None, base_url=None, forbid_dtd=False, forbid_entities=True):
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if parser is None:
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parser = getDefaultParser()
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elementtree = _etree.parse(source, parser, base_url=base_url)
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check_docinfo(elementtree, forbid_dtd, forbid_entities)
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return elementtree
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def fromstring(text, parser=None, base_url=None, forbid_dtd=False, forbid_entities=True):
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if parser is None:
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parser = getDefaultParser()
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rootelement = _etree.fromstring(text, parser, base_url=base_url)
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elementtree = rootelement.getroottree()
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check_docinfo(elementtree, forbid_dtd, forbid_entities)
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return rootelement
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XML = fromstring
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def iterparse(*args, **kwargs):
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raise NotSupportedError("defused lxml.etree.iterparse not available")
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