Add google-endpoints to third_party/.

third_party/google-endpoints/oauth2client/flask_util.py

Index: third_party/google-endpoints/oauth2client/flask_util.py
diff --git a/third_party/google-endpoints/oauth2client/flask_util.py b/third_party/google-endpoints/oauth2client/flask_util.py
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+# Copyright 2015 Google Inc.  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.
+
+"""Utilities for the Flask web framework
+
+Provides a Flask extension that makes using OAuth2 web server flow easier.
+The extension includes views that handle the entire auth flow and a
+``@required`` decorator to automatically ensure that user credentials are
+available.
+
+
+Configuration
+=============
+
+To configure, you'll need a set of OAuth2 web application credentials from the
+`Google Developer's Console <https://console.developers.google.com/project/_/\
+apiui/credential>`__.
+
+.. code-block:: python
+
+    from oauth2client.flask_util import UserOAuth2
+
+    app = Flask(__name__)
+
+    app.config['SECRET_KEY'] = 'your-secret-key'
+
+    app.config['GOOGLE_OAUTH2_CLIENT_SECRETS_JSON'] = 'client_secrets.json'
+
+    # or, specify the client id and secret separately
+    app.config['GOOGLE_OAUTH2_CLIENT_ID'] = 'your-client-id'
+    app.config['GOOGLE_OAUTH2_CLIENT_SECRET'] = 'your-client-secret'
+
+    oauth2 = UserOAuth2(app)
+
+
+Usage
+=====
+
+Once configured, you can use the :meth:`UserOAuth2.required` decorator to
+ensure that credentials are available within a view.
+
+.. code-block:: python
+   :emphasize-lines: 3,7,10
+
+    # Note that app.route should be the outermost decorator.
+    @app.route('/needs_credentials')
+    @oauth2.required
+    def example():
+        # http is authorized with the user's credentials and can be used
+        # to make http calls.
+        http = oauth2.http()
+
+        # Or, you can access the credentials directly
+        credentials = oauth2.credentials
+
+If you want credentials to be optional for a view, you can leave the decorator
+off and use :meth:`UserOAuth2.has_credentials` to check.
+
+.. code-block:: python
+   :emphasize-lines: 3
+
+    @app.route('/optional')
+    def optional():
+        if oauth2.has_credentials():
+            return 'Credentials found!'
+        else:
+            return 'No credentials!'
+
+
+When credentials are available, you can use :attr:`UserOAuth2.email` and
+:attr:`UserOAuth2.user_id` to access information from the `ID Token
+<https://developers.google.com/identity/protocols/OpenIDConnect?hl=en>`__, if
+available.
+
+.. code-block:: python
+   :emphasize-lines: 4
+
+    @app.route('/info')
+    @oauth2.required
+    def info():
+        return "Hello, {} ({})".format(oauth2.email, oauth2.user_id)
+
+
+URLs & Trigging Authorization
+=============================
+
+The extension will add two new routes to your application:
+
+    * ``"oauth2.authorize"`` -> ``/oauth2authorize``
+    * ``"oauth2.callback"`` -> ``/oauth2callback``
+
+When configuring your OAuth2 credentials on the Google Developer's Console, be
+sure to add ``http[s]://[your-app-url]/oauth2callback`` as an authorized
+callback url.
+
+Typically you don't not need to use these routes directly, just be sure to
+decorate any views that require credentials with ``@oauth2.required``. If
+needed, you can trigger authorization at any time by redirecting the user
+to the URL returned by :meth:`UserOAuth2.authorize_url`.
+
+.. code-block:: python
+   :emphasize-lines: 3
+
+    @app.route('/login')
+    def login():
+        return oauth2.authorize_url("/")
+
+
+Incremental Auth
+================
+
+This extension also supports `Incremental Auth <https://developers.google.com\
+/identity/protocols/OAuth2WebServer?hl=en#incrementalAuth>`__. To enable it,
+configure the extension with ``include_granted_scopes``.
+
+.. code-block:: python
+
+    oauth2 = UserOAuth2(app, include_granted_scopes=True)
+
+Then specify any additional scopes needed on the decorator, for example:
+
+.. code-block:: python
+   :emphasize-lines: 2,7
+
+    @app.route('/drive')
+    @oauth2.required(scopes=["https://www.googleapis.com/auth/drive"])
+    def requires_drive():
+        ...
+
+    @app.route('/calendar')
+    @oauth2.required(scopes=["https://www.googleapis.com/auth/calendar"])
+    def requires_calendar():
+        ...
+
+The decorator will ensure that the the user has authorized all specified scopes
+before allowing them to access the view, and will also ensure that credentials
+do not lose any previously authorized scopes.
+
+
+Storage
+=======
+
+By default, the extension uses a Flask session-based storage solution. This
+means that credentials are only available for the duration of a session. It
+also means that with Flask's default configuration, the credentials will be
+visible in the session cookie. It's highly recommended to use database-backed
+session and to use https whenever handling user credentials.
+
+If you need the credentials to be available longer than a user session or
+available outside of a request context, you will need to implement your own
+:class:`oauth2client.Storage`.
+"""
+
+import hashlib
+import json
+import os
+import pickle
+from functools import wraps
+
+import six.moves.http_client as httplib
+import httplib2
+
+try:
+    from flask import Blueprint
+    from flask import _app_ctx_stack
+    from flask import current_app
+    from flask import redirect
+    from flask import request
+    from flask import session
+    from flask import url_for
+except ImportError:  # pragma: NO COVER
+    raise ImportError('The flask utilities require flask 0.9 or newer.')
+
+from oauth2client.client import FlowExchangeError
+from oauth2client.client import OAuth2Credentials
+from oauth2client.client import OAuth2WebServerFlow
+from oauth2client.client import Storage
+from oauth2client import clientsecrets
+
+
+__author__ = 'jonwayne@google.com (Jon Wayne Parrott)'
+
+_DEFAULT_SCOPES = ('email',)
+_CREDENTIALS_KEY = 'google_oauth2_credentials'
+_FLOW_KEY = 'google_oauth2_flow_{0}'
+_CSRF_KEY = 'google_oauth2_csrf_token'
+
+
+def _get_flow_for_token(csrf_token):
+    """Retrieves the flow instance associated with a given CSRF token from
+    the Flask session."""
+    flow_pickle = session.get(
+        _FLOW_KEY.format(csrf_token), None)
+
+    if flow_pickle is None:
+        return None
+    else:
+        return pickle.loads(flow_pickle)
+
+
+class UserOAuth2(object):
+    """Flask extension for making OAuth 2.0 easier.
+
+    Configuration values:
+
+        * ``GOOGLE_OAUTH2_CLIENT_SECRETS_JSON`` path to a client secrets json
+          file, obtained from the credentials screen in the Google Developers
+          console.
+        * ``GOOGLE_OAUTH2_CLIENT_ID`` the oauth2 credentials' client ID. This
+          is only needed if ``GOOGLE_OAUTH2_CLIENT_SECRETS_JSON`` is not specified.
+        * ``GOOGLE_OAUTH2_CLIENT_SECRET`` the oauth2 credentials' client
+          secret. This is only needed if ``GOOGLE_OAUTH2_CLIENT_SECRETS_JSON`` is not
+          specified.
+
+    If app is specified, all arguments will be passed along to init_app.
+
+    If no app is specified, then you should call init_app in your application
+    factory to finish initialization.
+    """
+
+    def __init__(self, app=None, *args, **kwargs):
+        self.app = app
+        if app is not None:
+            self.init_app(app, *args, **kwargs)
+
+    def init_app(self, app, scopes=None, client_secrets_file=None,
+                 client_id=None, client_secret=None, authorize_callback=None,
+                 storage=None, **kwargs):
+        """Initialize this extension for the given app.
+
+        Arguments:
+            app: A Flask application.
+            scopes: Optional list of scopes to authorize.
+            client_secrets_file: Path to a file containing client secrets. You
+                can also specify the GOOGLE_OAUTH2_CLIENT_SECRETS_JSON config value.
+            client_id: If not specifying a client secrets file, specify the
+                OAuth2 client id. You can also specify the
+                GOOGLE_OAUTH2_CLIENT_ID config value. You must also provide a
+                client secret.
+            client_secret: The OAuth2 client secret. You can also specify the
+                GOOGLE_OAUTH2_CLIENT_SECRET config value.
+            authorize_callback: A function that is executed after successful
+                user authorization.
+            storage: A oauth2client.client.Storage subclass for storing the
+                credentials. By default, this is a Flask session based storage.
+            kwargs: Any additional args are passed along to the Flow
+                constructor.
+        """
+        self.app = app
+        self.authorize_callback = authorize_callback
+        self.flow_kwargs = kwargs
+
+        if storage is None:
+            storage = FlaskSessionStorage()
+        self.storage = storage
+
+        if scopes is None:
+            scopes = app.config.get('GOOGLE_OAUTH2_SCOPES', _DEFAULT_SCOPES)
+        self.scopes = scopes
+
+        self._load_config(client_secrets_file, client_id, client_secret)
+
+        app.register_blueprint(self._create_blueprint())
+
+    def _load_config(self, client_secrets_file, client_id, client_secret):
+        """Loads oauth2 configuration in order of priority.
+
+        Priority:
+            1. Config passed to the constructor or init_app.
+            2. Config passed via the GOOGLE_OAUTH2_CLIENT_SECRETS_FILE app
+               config.
+            3. Config passed via the GOOGLE_OAUTH2_CLIENT_ID and
+               GOOGLE_OAUTH2_CLIENT_SECRET app config.
+
+        Raises:
+            ValueError if no config could be found.
+        """
+        if client_id and client_secret:
+            self.client_id, self.client_secret = client_id, client_secret
+            return
+
+        if client_secrets_file:
+            self._load_client_secrets(client_secrets_file)
+            return
+
+        if 'GOOGLE_OAUTH2_CLIENT_SECRETS_FILE' in self.app.config:
+            self._load_client_secrets(
+                self.app.config['GOOGLE_OAUTH2_CLIENT_SECRETS_FILE'])
+            return
+
+        try:
+            self.client_id, self.client_secret = (
+                self.app.config['GOOGLE_OAUTH2_CLIENT_ID'],
+                self.app.config['GOOGLE_OAUTH2_CLIENT_SECRET'])
+        except KeyError:
+            raise ValueError(
+                'OAuth2 configuration could not be found. Either specify the '
+                'client_secrets_file or client_id and client_secret or set the'
+                'app configuration variables '
+                'GOOGLE_OAUTH2_CLIENT_SECRETS_FILE or '
+                'GOOGLE_OAUTH2_CLIENT_ID and GOOGLE_OAUTH2_CLIENT_SECRET.')
+
+    def _load_client_secrets(self, filename):
+        """Loads client secrets from the given filename."""
+        client_type, client_info = clientsecrets.loadfile(filename)
+        if client_type != clientsecrets.TYPE_WEB:
+            raise ValueError(
+                'The flow specified in {0} is not supported.'.format(
+                    client_type))
+
+        self.client_id = client_info['client_id']
+        self.client_secret = client_info['client_secret']
+
+    def _make_flow(self, return_url=None, **kwargs):
+        """Creates a Web Server Flow"""
+        # Generate a CSRF token to prevent malicious requests.
+        csrf_token = hashlib.sha256(os.urandom(1024)).hexdigest()
+
+        session[_CSRF_KEY] = csrf_token
+
+        state = json.dumps({
+            'csrf_token': csrf_token,
+            'return_url': return_url
+        })
+
+        kw = self.flow_kwargs.copy()
+        kw.update(kwargs)
+
+        extra_scopes = kw.pop('scopes', [])
+        scopes = set(self.scopes).union(set(extra_scopes))
+
+        flow = OAuth2WebServerFlow(
+            client_id=self.client_id,
+            client_secret=self.client_secret,
+            scope=scopes,
+            state=state,
+            redirect_uri=url_for('oauth2.callback', _external=True),
+            **kw)
+
+        flow_key = _FLOW_KEY.format(csrf_token)
+        session[flow_key] = pickle.dumps(flow)
+
+        return flow
+
+    def _create_blueprint(self):
+        bp = Blueprint('oauth2', __name__)
+        bp.add_url_rule('/oauth2authorize', 'authorize', self.authorize_view)
+        bp.add_url_rule('/oauth2callback', 'callback', self.callback_view)
+
+        return bp
+
+    def authorize_view(self):
+        """Flask view that starts the authorization flow.
+
+        Starts flow by redirecting the user to the OAuth2 provider.
+        """
+        args = request.args.to_dict()
+
+        # Scopes will be passed as mutliple args, and to_dict() will only
+        # return one. So, we use getlist() to get all of the scopes.
+        args['scopes'] = request.args.getlist('scopes')
+
+        return_url = args.pop('return_url', None)
+        if return_url is None:
+            return_url = request.referrer or '/'
+
+        flow = self._make_flow(return_url=return_url, **args)
+        auth_url = flow.step1_get_authorize_url()
+
+        return redirect(auth_url)
+
+    def callback_view(self):
+        """Flask view that handles the user's return from OAuth2 provider.
+
+        On return, exchanges the authorization code for credentials and stores
+        the credentials.
+        """
+        if 'error' in request.args:
+            reason = request.args.get(
+                'error_description', request.args.get('error', ''))
+            return ('Authorization failed: {0}'.format(reason),
+                    httplib.BAD_REQUEST)
+
+        try:
+            encoded_state = request.args['state']
+            server_csrf = session[_CSRF_KEY]
+            code = request.args['code']
+        except KeyError:
+            return 'Invalid request', httplib.BAD_REQUEST
+
+        try:
+            state = json.loads(encoded_state)
+            client_csrf = state['csrf_token']
+            return_url = state['return_url']
+        except (ValueError, KeyError):
+            return 'Invalid request state', httplib.BAD_REQUEST
+
+        if client_csrf != server_csrf:
+            return 'Invalid request state', httplib.BAD_REQUEST
+
+        flow = _get_flow_for_token(server_csrf)
+
+        if flow is None:
+            return 'Invalid request state', httplib.BAD_REQUEST
+
+        # Exchange the auth code for credentials.
+        try:
+            credentials = flow.step2_exchange(code)
+        except FlowExchangeError as exchange_error:
+            current_app.logger.exception(exchange_error)
+            content = 'An error occurred: {0}'.format(exchange_error)
+            return content, httplib.BAD_REQUEST
+
+        # Save the credentials to the storage.
+        self.storage.put(credentials)
+
+        if self.authorize_callback:
+            self.authorize_callback(credentials)
+
+        return redirect(return_url)
+
+    @property
+    def credentials(self):
+        """The credentials for the current user or None if unavailable."""
+        ctx = _app_ctx_stack.top
+
+        if not hasattr(ctx, _CREDENTIALS_KEY):
+            ctx.google_oauth2_credentials = self.storage.get()
+
+        return ctx.google_oauth2_credentials
+
+    def has_credentials(self):
+        """Returns True if there are valid credentials for the current user."""
+        return self.credentials and not self.credentials.invalid
+
+    @property
+    def email(self):
+        """Returns the user's email address or None if there are no credentials.
+
+        The email address is provided by the current credentials' id_token.
+        This should not be used as unique identifier as the user can change
+        their email. If you need a unique identifier, use user_id.
+        """
+        if not self.credentials:
+            return None
+        try:
+            return self.credentials.id_token['email']
+        except KeyError:
+            current_app.logger.error(
+                'Invalid id_token {0}'.format(self.credentials.id_token))
+
+    @property
+    def user_id(self):
+        """Returns the a unique identifier for the user
+
+        Returns None if there are no credentials.
+
+        The id is provided by the current credentials' id_token.
+        """
+        if not self.credentials:
+            return None
+        try:
+            return self.credentials.id_token['sub']
+        except KeyError:
+            current_app.logger.error(
+                'Invalid id_token {0}'.format(self.credentials.id_token))
+
+    def authorize_url(self, return_url, **kwargs):
+        """Creates a URL that can be used to start the authorization flow.
+
+        When the user is directed to the URL, the authorization flow will
+        begin. Once complete, the user will be redirected to the specified
+        return URL.
+
+        Any kwargs are passed into the flow constructor.
+        """
+        return url_for('oauth2.authorize', return_url=return_url, **kwargs)
+
+    def required(self, decorated_function=None, scopes=None,
+                 **decorator_kwargs):
+        """Decorator to require OAuth2 credentials for a view.
+
+        If credentials are not available for the current user, then they will
+        be redirected to the authorization flow. Once complete, the user will
+        be redirected back to the original page.
+        """
+
+        def curry_wrapper(wrapped_function):
+            @wraps(wrapped_function)
+            def required_wrapper(*args, **kwargs):
+                return_url = decorator_kwargs.pop('return_url', request.url)
+
+                requested_scopes = set(self.scopes)
+                if scopes is not None:
+                    requested_scopes |= set(scopes)
+                if self.has_credentials():
+                    requested_scopes |= self.credentials.scopes
+
+                requested_scopes = list(requested_scopes)
+
+                # Does the user have credentials and does the credentials have
+                # all of the needed scopes?
+                if (self.has_credentials() and
+                        self.credentials.has_scopes(requested_scopes)):
+                    return wrapped_function(*args, **kwargs)
+                # Otherwise, redirect to authorization
+                else:
+                    auth_url = self.authorize_url(
+                        return_url,
+                        scopes=requested_scopes,
+                        **decorator_kwargs)
+
+                    return redirect(auth_url)
+
+            return required_wrapper
+
+        if decorated_function:
+            return curry_wrapper(decorated_function)
+        else:
+            return curry_wrapper
+
+    def http(self, *args, **kwargs):
+        """Returns an authorized http instance.
+
+        Can only be called if there are valid credentials for the user, such
+        as inside of a view that is decorated with @required.
+
+        Args:
+            *args: Positional arguments passed to httplib2.Http constructor.
+            **kwargs: Positional arguments passed to httplib2.Http constructor.
+
+        Raises:
+            ValueError if no credentials are available.
+        """
+        if not self.credentials:
+            raise ValueError('No credentials available.')
+        return self.credentials.authorize(httplib2.Http(*args, **kwargs))
+
+
+class FlaskSessionStorage(Storage):
+    """Storage implementation that uses Flask sessions.
+
+    Note that flask's default sessions are signed but not encrypted. Users
+    can see their own credentials and non-https connections can intercept user
+    credentials. We strongly recommend using a server-side session
+    implementation.
+    """
+
+    def locked_get(self):
+        serialized = session.get(_CREDENTIALS_KEY)
+
+        if serialized is None:
+            return None
+
+        credentials = OAuth2Credentials.from_json(serialized)
+        credentials.set_store(self)
+
+        return credentials
+
+    def locked_put(self, credentials):
+        session[_CREDENTIALS_KEY] = credentials.to_json()
+
+    def locked_delete(self):
+        if _CREDENTIALS_KEY in session:
+            del session[_CREDENTIALS_KEY]