386 lines
13 KiB
Python
386 lines
13 KiB
Python
# Copyright 2012 OpenStack Foundation
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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Dict <--> XML de/serializer.
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The identity API prefers attributes over elements, so we serialize that way
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by convention, with a few hardcoded exceptions.
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"""
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import re
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import six
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try:
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from lxml import etree
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except ImportError:
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etree = None
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from keystone import exception
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from keystone.i18n import _
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from keystone.openstack.common import log as logging
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LOG = logging.getLogger(__name__)
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DOCTYPE = '<?xml version="1.0" encoding="UTF-8"?>'
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XMLNS = 'http://docs.openstack.org/identity/api/v2.0'
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XMLNS_LIST = [
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{
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'value': 'http://docs.openstack.org/identity/api/v2.0'
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},
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{
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'prefix': 'OS-KSADM',
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'value': 'http://docs.openstack.org/identity/api/ext/OS-KSADM/v1.0',
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},
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]
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E_LXML_NOT_INSTALLED = _('lxml is not installed.')
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def from_xml(xml):
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"""Deserialize XML to a dictionary."""
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if xml is None:
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return None
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deserializer = XmlDeserializer()
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return deserializer(xml)
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def to_xml(d, xmlns=None):
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"""Serialize a dictionary to XML."""
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if d is None:
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return None
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serialize = XmlSerializer()
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return serialize(d, xmlns)
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class XmlDeserializer(object):
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def __init__(self):
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if etree is None:
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LOG.warning(E_LXML_NOT_INSTALLED)
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raise exception.UnexpectedError(E_LXML_NOT_INSTALLED)
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self.parser = etree.XMLParser(resolve_entities=False,
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remove_comments=True,
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remove_pis=True)
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# NOTE(dolph): lxml.etree.Entity() is just a callable that currently
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# returns an lxml.etree._Entity instance, which doesn't appear to be
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# part of the public API, so we discover the type dynamically to be
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# safe
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self.entity_type = type(etree.Entity('x'))
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def __call__(self, xml_str):
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"""Returns a dictionary populated by decoding the given xml string."""
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dom = etree.fromstring(xml_str.strip(), self.parser)
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return self.walk_element(dom, True)
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def _deserialize_links(self, links):
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return dict((x.attrib['rel'], x.attrib['href']) for x in links)
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@staticmethod
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def _qualified_name(tag, namespace):
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"""Returns a qualified tag name.
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The tag name may contain the namespace prefix or not, which can
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be determined by specifying the parameter namespace.
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"""
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m = re.search('[^}]+$', tag)
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tag_name = m.string[m.start():]
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if not namespace:
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return tag_name
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bracket = re.search('[^{]+$', tag)
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ns = m.string[bracket.start():m.start() - 1]
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# If the namespace is
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# http://docs.openstack.org/identity/api/ext/OS-KSADM/v1.0 for the
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# root element, a prefix needs to add in front of the tag name.
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prefix = None
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for xmlns in XMLNS_LIST:
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if xmlns['value'] == ns:
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prefix = xmlns.get('prefix')
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break
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if prefix is not None:
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return '%(PREFIX)s:%(tag_name)s' % {
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'PREFIX': prefix, 'tag_name': tag_name}
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else:
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return tag_name
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def walk_element(self, element, namespace=False):
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"""Populates a dictionary by walking an etree element."""
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values = {}
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for k, v in six.iteritems(element.attrib):
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# boolean-looking attributes become booleans in JSON
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if k in ['enabled', 'truncated']:
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if v in ['true']:
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v = True
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elif v in ['false']:
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v = False
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values[self._qualified_name(k, namespace)] = v
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text = None
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if element.text is not None:
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text = element.text.strip()
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# current spec does not have attributes on an element with text
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values = values or text or {}
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decoded_tag = XmlDeserializer._qualified_name(element.tag, namespace)
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list_item_tag = None
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if (decoded_tag[-1] == 's' and not values and
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decoded_tag != 'access'):
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# FIXME(gyee): special-case lists for now unti we
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# figure out how to properly handle them.
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# If any key ends with an 's', we are assuming it is a list.
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# List element have no attributes.
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values = list(values)
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if decoded_tag == 'policies':
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list_item_tag = 'policy'
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else:
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list_item_tag = decoded_tag[:-1]
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if decoded_tag == 'links':
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return {'links': self._deserialize_links(element)}
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links = None
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truncated = False
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for child in [self.walk_element(x) for x in element
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if not isinstance(x, self.entity_type)]:
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if list_item_tag:
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# FIXME(gyee): special-case lists for now until we
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# figure out how to properly handle them.
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# If any key ends with an 's', we are assuming it is a list.
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if list_item_tag in child:
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values.append(child[list_item_tag])
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else:
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if 'links' in child:
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links = child['links']
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else:
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truncated = child['truncated']
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else:
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values = dict(values.items() + child.items())
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# set empty and none-list element to None to align with JSON
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if not values:
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values = ""
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d = {XmlDeserializer._qualified_name(element.tag, namespace): values}
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if links:
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d['links'] = links
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d['links'].setdefault('next')
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d['links'].setdefault('previous')
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if truncated:
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d['truncated'] = truncated['truncated']
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return d
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class XmlSerializer(object):
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def __init__(self):
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if etree is None:
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LOG.warning(E_LXML_NOT_INSTALLED)
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raise exception.UnexpectedError(E_LXML_NOT_INSTALLED)
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def __call__(self, d, xmlns=None):
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"""Returns an xml etree populated by the given dictionary.
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Optionally, namespace the etree by specifying an ``xmlns``.
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"""
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links = None
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truncated = False
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# FIXME(dolph): skipping links for now
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for key in d.keys():
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if '_links' in key:
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d.pop(key)
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# NOTE(gyee, henry-nash): special-case links and truncation
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# attribute in collections
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if 'links' == key:
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if links:
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# we have multiple links
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raise Exception('Multiple links found')
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links = d.pop(key)
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if 'truncated' == key:
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if truncated:
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# we have multiple attributes
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raise Exception(_('Multiple truncation attributes found'))
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truncated = d.pop(key)
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assert len(d.keys()) == 1, ('Cannot encode more than one root '
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'element: %s' % d.keys())
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# name the root dom element
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name = d.keys()[0]
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m = re.search('[^:]+$', name)
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root_name = m.string[m.start():]
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prefix = m.string[0:m.start() - 1]
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for ns in XMLNS_LIST:
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if prefix == ns.get('prefix'):
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xmlns = ns['value']
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break
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# only the root dom element gets an xlmns
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root = etree.Element(root_name, xmlns=(xmlns or XMLNS))
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self.populate_element(root, d[name])
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# NOTE(gyee, henry-nash): special-case links and truncation attribute
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if links:
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self._populate_links(root, links)
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if truncated:
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self._populate_truncated(root, truncated)
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# TODO(dolph): you can get a doctype from lxml, using ElementTrees
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return '%s\n%s' % (DOCTYPE, etree.tostring(root, pretty_print=True))
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def _populate_links(self, element, links_json):
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links = etree.Element('links')
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for k, v in six.iteritems(links_json):
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if v:
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link = etree.Element('link')
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link.set('rel', six.text_type(k))
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link.set('href', six.text_type(v))
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links.append(link)
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element.append(links)
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def _populate_truncated(self, element, truncated_value):
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truncated = etree.Element('truncated')
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self._populate_bool(truncated, 'truncated', truncated_value)
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element.append(truncated)
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def _populate_list(self, element, k, v):
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"""Populates an element with a key & list value."""
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# spec has a lot of inconsistency here!
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container = element
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if k == 'media-types':
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# xsd compliance: <media-types> contains <media-type>s
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# find an existing <media-types> element or make one
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container = element.find('media-types')
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if container is None:
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container = etree.Element(k)
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element.append(container)
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name = k[:-1]
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elif k == 'serviceCatalog' or k == 'catalog':
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# xsd compliance: <serviceCatalog> contains <service>s
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container = etree.Element(k)
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element.append(container)
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name = 'service'
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elif k == 'roles' and element.tag == 'user':
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name = 'role'
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elif k == 'endpoints' and element.tag == 'service':
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name = 'endpoint'
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elif k == 'values' and element.tag[-1] == 's':
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# OS convention is to contain lists in a 'values' element,
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# so the list itself can have attributes, which is
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# unnecessary in XML
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name = element.tag[:-1]
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elif k[-1] == 's':
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container = etree.Element(k)
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element.append(container)
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if k == 'policies':
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# need to special-case policies since policie is not a word
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name = 'policy'
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else:
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name = k[:-1]
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else:
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name = k
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for item in v:
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child = etree.Element(name)
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self.populate_element(child, item)
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container.append(child)
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def _populate_dict(self, element, k, v):
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"""Populates an element with a key & dictionary value."""
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if k == 'links':
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# links is a special dict
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self._populate_links(element, v)
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else:
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child = etree.Element(k)
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self.populate_element(child, v)
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element.append(child)
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def _populate_bool(self, element, k, v):
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"""Populates an element with a key & boolean value."""
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# booleans are 'true' and 'false'
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element.set(k, six.text_type(v).lower())
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def _populate_str(self, element, k, v):
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"""Populates an element with a key & string value."""
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if k in ['description']:
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# always becomes an element
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child = etree.Element(k)
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child.text = six.text_type(v)
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element.append(child)
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else:
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# add attributes to the current element
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element.set(k, six.text_type(v))
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def _populate_number(self, element, k, v):
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"""Populates an element with a key & numeric value."""
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# numbers can be handled as strings
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self._populate_str(element, k, v)
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def populate_element(self, element, value):
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"""Populates an etree with the given value."""
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if isinstance(value, list):
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self._populate_sequence(element, value)
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elif isinstance(value, dict):
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self._populate_tree(element, value)
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# NOTE(blk-u): For compatibility with Folsom, when serializing the
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# v2.0 version element also add the links to the base element.
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if value.get('id') == 'v2.0':
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for item in value['links']:
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child = etree.Element('link')
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self.populate_element(child, item)
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element.append(child)
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elif isinstance(value, six.string_types):
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element.text = six.text_type(value)
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def _populate_sequence(self, element, l):
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"""Populates an etree with a sequence of elements, given a list."""
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# xsd compliance: child elements are singular: <users> has <user>s
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name = element.tag
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if element.tag[-1] == 's':
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name = element.tag[:-1]
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if name == 'policie':
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name = 'policy'
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for item in l:
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child = etree.Element(name)
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self.populate_element(child, item)
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element.append(child)
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def _populate_tree(self, element, d):
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"""Populates an etree with attributes & elements, given a dict."""
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for k, v in six.iteritems(d):
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if isinstance(v, dict):
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self._populate_dict(element, k, v)
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elif isinstance(v, list):
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self._populate_list(element, k, v)
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elif isinstance(v, bool):
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self._populate_bool(element, k, v)
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elif isinstance(v, six.string_types):
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self._populate_str(element, k, v)
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elif type(v) in [int, float, long, complex]:
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self._populate_number(element, k, v)
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