123 lines
5.1 KiB
Python
123 lines
5.1 KiB
Python
#
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# Copyright 2013 IBM Corp.
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# Copyright 2012 New Dream Network, LLC (DreamHost)
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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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from lxml import etree
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import webob
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from ceilometer.api import hooks
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from ceilometer import i18n
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from ceilometer.i18n import _
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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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@staticmethod
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def best_match_language(accept_language):
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"""Determines best available locale from the Accept-Language header.
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:returns: the best language match or None if the 'Accept-Language'
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header was not available in the request.
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"""
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if not accept_language:
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return None
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all_languages = i18n.get_available_languages()
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return accept_language.best_match(all_languages)
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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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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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# Find the first TranslationHook in the array of hooks and use the
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# translatable_error object from it
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error = None
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for hook in self.app.hooks:
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if isinstance(hook, hooks.TranslationHook):
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error = hook.local_error.translatable_error
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break
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user_locale = self.best_match_language(req.accept_language)
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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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fault = etree.fromstring('\n'.join(app_iter))
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# Add the translated error to the xml data
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if error is not None:
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for fault_string in fault.findall('faultstring'):
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fault_string.text = i18n.translate(error,
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user_locale)
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body = ['<error_message>' + etree.tostring(fault)
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+ '</error_message>']
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except etree.XMLSyntaxError 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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try:
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fault = json.loads('\n'.join(app_iter))
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if error is not None and 'faultstring' in fault:
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fault['faultstring'] = i18n.translate(error,
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user_locale)
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body = [json.dumps({'error_message': fault})]
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except ValueError as err:
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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', str(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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