168 lines
5.4 KiB
Python
168 lines
5.4 KiB
Python
#!/usr/bin/env python
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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#
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# Copyright (c) 2010 OpenStack, LLC.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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# implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""
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Auth Middleware that accepts URL query extension.
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This module can be installed as a filter in front of your service to
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detect extension in the resource URI (e.g., foo/resource.xml) to
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specify HTTP response body type. If an extension is specified, it
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overwrites the Accept header in the request, if present.
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"""
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import webob.acceptparse
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# Maps supported URL prefixes to API_VERSION
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PATH_PREFIXES = {
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'/v2.0': '2.0',
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'/v1.1': '1.1',
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'/v1.0': '1.0'}
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# Maps supported URL extensions to RESPONSE_ENCODING
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PATH_SUFFIXES = {
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'.json': 'json',
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'.xml': 'xml'}
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# Maps supported Accept headers to RESPONSE_ENCODING and API_VERSION
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ACCEPT_HEADERS = {
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'application/vnd.openstack.identity-v2.0+json': ('json', '2.0'),
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'application/vnd.openstack.identity-v2.0+xml': ('xml', '2.0'),
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'application/vnd.openstack.identity-v1.1+json': ('json', '1.1'),
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'application/vnd.openstack.identity-v1.1+xml': ('xml', '1.1'),
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'application/vnd.openstack.identity-v1.0+json': ('json', '1.0'),
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'application/vnd.openstack.identity-v1.0+xml': ('xml', '1.0'),
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'application/json': ('json', None),
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'application/xml': ('xml', None)}
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DEFAULT_RESPONSE_ENCODING = 'json'
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DEFAULT_API_VERSION = '2.0'
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class NormalizingFilter(object):
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"""Middleware filter to handle URL and Accept header normalization"""
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def __init__(self, app, conf):
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# app is the next app in WSGI chain - eventually the OpenStack service
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self.app = app
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self.conf = conf
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def __call__(self, env, start_response):
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# Inspect the request for mime type and API version
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env = normalize_accept_header(env)
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env = normalize_path_prefix(env)
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env = normalize_path_suffix(env)
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env['PATH_INFO'] = normalize_starting_slash(env.get('PATH_INFO'))
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env['PATH_INFO'] = normalize_trailing_slash(env['PATH_INFO'])
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# Fall back on defaults, if necessary
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env['KEYSTONE_API_VERSION'] = env.get(
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'KEYSTONE_API_VERSION') or DEFAULT_API_VERSION
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env['KEYSTONE_RESPONSE_ENCODING'] = env.get(
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'KEYSTONE_RESPONSE_ENCODING') or DEFAULT_RESPONSE_ENCODING
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env['HTTP_ACCEPT'] = 'application/' + (env.get(
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'KEYSTONE_RESPONSE_ENCODING') or DEFAULT_RESPONSE_ENCODING)
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return self.app(env, start_response)
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def normalize_accept_header(env):
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"""Matches the preferred Accept encoding to supported encodings.
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Sets KEYSTONE_RESPONSE_ENCODING and KEYSTONE_API_VERSION, if appropriate.
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"""
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if env.get('HTTP_ACCEPT'):
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accept = webob.acceptparse.Accept('Accept', env.get('HTTP_ACCEPT'))
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best_accept = accept.best_match(ACCEPT_HEADERS.keys())
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if best_accept:
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response_encoding, api_version = ACCEPT_HEADERS[best_accept]
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if response_encoding:
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env['KEYSTONE_RESPONSE_ENCODING'] = response_encoding
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if api_version:
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env['KEYSTONE_API_VERSION'] = api_version
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return env
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def normalize_path_prefix(env):
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"""Handles recognized PATH_INFO prefixes.
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Looks for a version prefix on the PATH_INFO, sets KEYSTONE_API_VERSION
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accordingly, and removes the prefix to normalize the request."""
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for prefix in PATH_PREFIXES.keys():
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if env['PATH_INFO'].startswith(prefix):
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env['KEYSTONE_API_VERSION'] = PATH_PREFIXES[prefix]
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env['PATH_INFO'] = env['PATH_INFO'][len(prefix):]
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break
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return env
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def normalize_path_suffix(env):
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"""Hnadles recognized PATH_INFO suffixes.
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Looks for a recognized suffix on the PATH_INFO, sets the
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KEYSTONE_RESPONSE_ENCODING accordingly, and removes the suffix to normalize
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the request."""
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for suffix in PATH_SUFFIXES.keys():
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if env['PATH_INFO'].endswith(suffix):
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env['KEYSTONE_RESPONSE_ENCODING'] = PATH_SUFFIXES[suffix]
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env['PATH_INFO'] = env['PATH_INFO'][:-len(suffix)]
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break
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return env
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def normalize_starting_slash(path_info):
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"""Removes a trailing slash from the given path, if any."""
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# Ensure the path at least contains a slash
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if not path_info:
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return '/'
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# Ensure the path starts with a slash
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elif path_info[0] != '/':
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return '/' + path_info
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# No need to change anything
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else:
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return path_info
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def normalize_trailing_slash(path_info):
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"""Removes a trailing slash from the given path, if any."""
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# Remove trailing slash, unless it's the only char
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if len(path_info) > 1 and path_info[-1] == '/':
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return path_info[:-1]
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# No need to change anything
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else:
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return path_info
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def filter_factory(global_conf, **local_conf):
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"""Returns a WSGI filter app for use with paste.deploy."""
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conf = global_conf.copy()
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conf.update(local_conf)
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def ext_filter(app):
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return NormalizingFilter(app, conf)
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return ext_filter
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