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1# Copyright 2014 Google Inc. All rights reserved.
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7#      http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14
15"""Utilities for reading OAuth 2.0 client secret files.
16
17A client_secrets.json file contains all the information needed to interact with
18an OAuth 2.0 protected service.
19"""
20
21import json
22
23import six
24
25__author__ = 'jcgregorio@google.com (Joe Gregorio)'
26
27# Properties that make a client_secrets.json file valid.
28TYPE_WEB = 'web'
29TYPE_INSTALLED = 'installed'
30
31VALID_CLIENT = {
32    TYPE_WEB: {
33        'required': [
34            'client_id',
35            'client_secret',
36            'redirect_uris',
37            'auth_uri',
38            'token_uri',
39        ],
40        'string': [
41            'client_id',
42            'client_secret',
43        ],
44    },
45    TYPE_INSTALLED: {
46        'required': [
47            'client_id',
48            'client_secret',
49            'redirect_uris',
50            'auth_uri',
51            'token_uri',
52        ],
53        'string': [
54            'client_id',
55            'client_secret',
56        ],
57    },
58}
59
60
61class Error(Exception):
62    """Base error for this module."""
63
64
65class InvalidClientSecretsError(Error):
66    """Format of ClientSecrets file is invalid."""
67
68
69def _validate_clientsecrets(clientsecrets_dict):
70    """Validate parsed client secrets from a file.
71
72    Args:
73        clientsecrets_dict: dict, a dictionary holding the client secrets.
74
75    Returns:
76        tuple, a string of the client type and the information parsed
77        from the file.
78    """
79    _INVALID_FILE_FORMAT_MSG = (
80        'Invalid file format. See '
81        'https://developers.google.com/api-client-library/'
82        'python/guide/aaa_client_secrets')
83
84    if clientsecrets_dict is None:
85        raise InvalidClientSecretsError(_INVALID_FILE_FORMAT_MSG)
86    try:
87        (client_type, client_info), = clientsecrets_dict.items()
88    except (ValueError, AttributeError):
89        raise InvalidClientSecretsError(
90            _INVALID_FILE_FORMAT_MSG + ' '
91            'Expected a JSON object with a single property for a "web" or '
92            '"installed" application')
93
94    if client_type not in VALID_CLIENT:
95        raise InvalidClientSecretsError(
96            'Unknown client type: {0}.'.format(client_type))
97
98    for prop_name in VALID_CLIENT[client_type]['required']:
99        if prop_name not in client_info:
100            raise InvalidClientSecretsError(
101                'Missing property "{0}" in a client type of "{1}".'.format(
102                    prop_name, client_type))
103    for prop_name in VALID_CLIENT[client_type]['string']:
104        if client_info[prop_name].startswith('[['):
105            raise InvalidClientSecretsError(
106                'Property "{0}" is not configured.'.format(prop_name))
107    return client_type, client_info
108
109
110def load(fp):
111    obj = json.load(fp)
112    return _validate_clientsecrets(obj)
113
114
115def loads(s):
116    obj = json.loads(s)
117    return _validate_clientsecrets(obj)
118
119
120def _loadfile(filename):
121    try:
122        with open(filename, 'r') as fp:
123            obj = json.load(fp)
124    except IOError as exc:
125        raise InvalidClientSecretsError('Error opening file', exc.filename,
126                                        exc.strerror, exc.errno)
127    return _validate_clientsecrets(obj)
128
129
130def loadfile(filename, cache=None):
131    """Loading of client_secrets JSON file, optionally backed by a cache.
132
133    Typical cache storage would be App Engine memcache service,
134    but you can pass in any other cache client that implements
135    these methods:
136
137    * ``get(key, namespace=ns)``
138    * ``set(key, value, namespace=ns)``
139
140    Usage::
141
142        # without caching
143        client_type, client_info = loadfile('secrets.json')
144        # using App Engine memcache service
145        from google.appengine.api import memcache
146        client_type, client_info = loadfile('secrets.json', cache=memcache)
147
148    Args:
149        filename: string, Path to a client_secrets.json file on a filesystem.
150        cache: An optional cache service client that implements get() and set()
151        methods. If not specified, the file is always being loaded from
152                 a filesystem.
153
154    Raises:
155        InvalidClientSecretsError: In case of a validation error or some
156                                   I/O failure. Can happen only on cache miss.
157
158    Returns:
159        (client_type, client_info) tuple, as _loadfile() normally would.
160        JSON contents is validated only during first load. Cache hits are not
161        validated.
162    """
163    _SECRET_NAMESPACE = 'oauth2client:secrets#ns'
164
165    if not cache:
166        return _loadfile(filename)
167
168    obj = cache.get(filename, namespace=_SECRET_NAMESPACE)
169    if obj is None:
170        client_type, client_info = _loadfile(filename)
171        obj = {client_type: client_info}
172        cache.set(filename, obj, namespace=_SECRET_NAMESPACE)
173
174    return next(six.iteritems(obj))
175