/usr/share/pyshared/glance/api/middleware/version_negotiation.py is in python-glance 2012.1.3+stable~20120821-120fcf-0ubuntu1.5.
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# Copyright 2011 OpenStack LLC.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
A filter middleware that inspects the requested URI for a version string
and/or Accept headers and attempts to negotiate an API controller to
return
"""
import logging
import re
from glance.api import versions
from glance.common import wsgi
logger = logging.getLogger('glance.api.middleware.version_negotiation')
class VersionNegotiationFilter(wsgi.Middleware):
def __init__(self, app, conf, **local_conf):
self.versions_app = versions.Controller(conf)
self.version_uri_regex = re.compile(r"^v(\d+)\.?(\d+)?")
self.conf = conf
super(VersionNegotiationFilter, self).__init__(app)
def process_request(self, req):
"""
If there is a version identifier in the URI, simply
return the correct API controller, otherwise, if we
find an Accept: header, process it
"""
# See if a version identifier is in the URI passed to
# us already. If so, simply return the right version
# API controller
msg = _("Processing request: %(method)s %(path)s Accept: "
"%(accept)s") % ({'method': req.method,
'path': req.path, 'accept': req.accept})
logger.debug(msg)
# If the request is for /versions, just return the versions container
if req.path_info_peek() == "versions":
return self.versions_app
match = self._match_version_string(req.path_info_peek(), req)
if match:
if (req.environ['api.major_version'] == 1 and
req.environ['api.minor_version'] == 0):
logger.debug(_("Matched versioned URI. Version: %d.%d"),
req.environ['api.major_version'],
req.environ['api.minor_version'])
# Strip the version from the path
req.path_info_pop()
return None
else:
logger.debug(_("Unknown version in versioned URI: %d.%d. "
"Returning version choices."),
req.environ['api.major_version'],
req.environ['api.minor_version'])
return self.versions_app
accept = str(req.accept)
if accept.startswith('application/vnd.openstack.images-'):
token_loc = len('application/vnd.openstack.images-')
accept_version = accept[token_loc:]
match = self._match_version_string(accept_version, req)
if match:
if (req.environ['api.major_version'] == 1 and
req.environ['api.minor_version'] == 0):
logger.debug(_("Matched versioned media type. "
"Version: %d.%d"),
req.environ['api.major_version'],
req.environ['api.minor_version'])
return None
else:
logger.debug(_("Unknown version in accept header: %d.%d..."
"returning version choices."),
req.environ['api.major_version'],
req.environ['api.minor_version'])
return self.versions_app
else:
if req.accept not in ('*/*', ''):
logger.debug(_("Unknown accept header: %s..."
"returning version choices."), req.accept)
return self.versions_app
return None
def _match_version_string(self, subject, req):
"""
Given a subject string, tries to match a major and/or
minor version number. If found, sets the api.major_version
and api.minor_version environ variables.
Returns True if there was a match, false otherwise.
:param subject: The string to check
:param req: Webob.Request object
"""
match = self.version_uri_regex.match(subject)
if match:
major_version, minor_version = match.groups(0)
major_version = int(major_version)
minor_version = int(minor_version)
req.environ['api.major_version'] = major_version
req.environ['api.minor_version'] = minor_version
return match is not None
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