c7936656c0
Fixes bug 1206256 In Python 2.6 xml.etree.ElementTree.fromstring raises xml.parsers.expat.ExpatError instead of xml.etree.ElementTree.ParseError when faced with invalid xml. This change catches an import error and uses ExpatError instead of ParseError. Change-Id: I8ab41328c8eeacc28f4e01d730c73ff251df4a25
95 lines
3.8 KiB
Python
95 lines
3.8 KiB
Python
# -*- encoding: utf-8 -*-
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#
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# Copyright © 2012 New Dream Network, LLC (DreamHost)
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#
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# Author: Doug Hellmann <doug.hellmann@dreamhost.com>
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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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"""Middleware to replace the plain text message body of an error
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response with one formatted so the client can parse it.
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Based on pecan.middleware.errordocument
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"""
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import json
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import webob
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from xml import etree as et
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try:
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from xml.etree.ElementTree import ParseError
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except ImportError:
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from xml.parsers.expat import ExpatError as ParseError
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from ceilometer.openstack.common import log
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LOG = log.getLogger(__name__)
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class ParsableErrorMiddleware(object):
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"""Replace error body with something the client can parse.
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"""
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def __init__(self, app):
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self.app = app
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def __call__(self, environ, start_response):
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# Request for this state, modified by replace_start_response()
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# and used when an error is being reported.
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state = {}
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def replacement_start_response(status, headers, exc_info=None):
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"""Overrides the default response to make errors parsable.
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"""
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try:
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status_code = int(status.split(' ')[0])
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state['status_code'] = status_code
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except (ValueError, TypeError): # pragma: nocover
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raise Exception((
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'ErrorDocumentMiddleware received an invalid '
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'status %s' % status
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))
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else:
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if (state['status_code'] / 100) not in (2, 3):
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# Remove some headers so we can replace them later
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# when we have the full error message and can
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# compute the length.
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headers = [(h, v)
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for (h, v) in headers
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if h not in ('Content-Length', 'Content-Type')
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]
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# Save the headers in case we need to modify them.
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state['headers'] = headers
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return start_response(status, headers, exc_info)
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app_iter = self.app(environ, replacement_start_response)
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if (state['status_code'] / 100) not in (2, 3):
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req = webob.Request(environ)
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if (req.accept.best_match(['application/json', 'application/xml'])
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== 'application/xml'):
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try:
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# simple check xml is valid
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body = [et.ElementTree.tostring(
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et.ElementTree.fromstring('<error_message>'
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+ '\n'.join(app_iter)
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+ '</error_message>'))]
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except ParseError as err:
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LOG.error('Error parsing HTTP response: %s' % err)
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body = ['<error_message>%s' % state['status_code']
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+ '</error_message>']
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state['headers'].append(('Content-Type', 'application/xml'))
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else:
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body = [json.dumps({'error_message': '\n'.join(app_iter)})]
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state['headers'].append(('Content-Type', 'application/json'))
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state['headers'].append(('Content-Length', len(body[0])))
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else:
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body = app_iter
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return body
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