slixmpp/sleekxmpp/xmlstream/matcher/xmlmask.py

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2010-03-26 21:32:16 +00:00
"""
SleekXMPP: The Sleek XMPP Library
Copyright (C) 2010 Nathanael C. Fritz
This file is part of SleekXMPP.
See the file LICENSE for copying permission.
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"""
import logging
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from xml.parsers.expat import ExpatError
from sleekxmpp.xmlstream.stanzabase import ET
from sleekxmpp.xmlstream.matcher.base import MatcherBase
# Flag indicating if the builtin XPath matcher should be used, which
# uses namespaces, or a custom matcher that ignores namespaces.
# Changing this will affect ALL XMLMask matchers.
IGNORE_NS = False
log = logging.getLogger(__name__)
class MatchXMLMask(MatcherBase):
"""
The XMLMask matcher selects stanzas whose XML matches a given
XML pattern, or mask. For example, message stanzas with body elements
could be matched using the mask:
<message xmlns="jabber:client"><body /></message>
Use of XMLMask is discouraged, and XPath or StanzaPath should be used
instead.
The use of namespaces in the mask comparison is controlled by
IGNORE_NS. Setting IGNORE_NS to True will disable namespace based matching
for ALL XMLMask matchers.
Methods:
match -- Overrides MatcherBase.match.
setDefaultNS -- Set the default namespace for the mask.
"""
def __init__(self, criteria):
"""
Create a new XMLMask matcher.
Arguments:
criteria -- Either an XML object or XML string to use as a mask.
"""
MatcherBase.__init__(self, criteria)
if isinstance(criteria, str):
self._criteria = ET.fromstring(self._criteria)
self.default_ns = 'jabber:client'
def setDefaultNS(self, ns):
"""
Set the default namespace to use during comparisons.
Arguments:
ns -- The new namespace to use as the default.
"""
self.default_ns = ns
def match(self, xml):
"""
Compare a stanza object or XML object against the stored XML mask.
Overrides MatcherBase.match.
Arguments:
xml -- The stanza object or XML object to compare against.
"""
if hasattr(xml, 'xml'):
xml = xml.xml
return self._mask_cmp(xml, self._criteria, True)
def _mask_cmp(self, source, mask, use_ns=False, default_ns='__no_ns__'):
"""
Compare an XML object against an XML mask.
Arguments:
source -- The XML object to compare against the mask.
mask -- The XML object serving as the mask.
use_ns -- Indicates if namespaces should be respected during
the comparison.
default_ns -- The default namespace to apply to elements that
do not have a specified namespace.
Defaults to "__no_ns__".
"""
use_ns = not IGNORE_NS
if source is None:
# If the element was not found. May happend during recursive calls.
return False
# Convert the mask to an XML object if it is a string.
if not hasattr(mask, 'attrib'):
try:
mask = ET.fromstring(mask)
except ExpatError:
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log.warning("Expat error: %s\nIn parsing: %s", '', mask)
if not use_ns:
# Compare the element without using namespaces.
source_tag = source.tag.split('}', 1)[-1]
mask_tag = mask.tag.split('}', 1)[-1]
if source_tag != mask_tag:
return False
else:
# Compare the element using namespaces
mask_ns_tag = "{%s}%s" % (self.default_ns, mask.tag)
if source.tag not in [mask.tag, mask_ns_tag]:
return False
# If the mask includes text, compare it.
if mask.text and source.text and \
source.text.strip() != mask.text.strip():
return False
# Compare attributes. The stanza must include the attributes
# defined by the mask, but may include others.
for name, value in mask.attrib.items():
if source.attrib.get(name, "__None__") != value:
return False
# Recursively check subelements.
matched_elements = {}
for subelement in mask:
if use_ns:
matched = False
for other in source.findall(subelement.tag):
matched_elements[other] = False
if self._mask_cmp(other, subelement, use_ns):
if not matched_elements.get(other, False):
matched_elements[other] = True
matched = True
if not matched:
return False
else:
if not self._mask_cmp(self._get_child(source, subelement.tag),
subelement, use_ns):
return False
# Everything matches.
return True
def _get_child(self, xml, tag):
"""
Return a child element given its tag, ignoring namespace values.
Returns None if the child was not found.
Arguments:
xml -- The XML object to search for the given child tag.
tag -- The name of the subelement to find.
"""
tag = tag.split('}')[-1]
try:
children = [c.tag.split('}')[-1] for c in xml.getchildren()]
index = children.index(tag)
except ValueError:
return None
return xml.getchildren()[index]