487 lines
14 KiB
Python
487 lines
14 KiB
Python
|
# -*- coding: utf-8 -*-
|
||
|
"""
|
||
|
flask_principal
|
||
|
~~~~~~~~~~~~~~~
|
||
|
|
||
|
Identity management for Flask.
|
||
|
|
||
|
:copyright: (c) 2012 by Ali Afshar.
|
||
|
:license: MIT, see LICENSE for more details.
|
||
|
|
||
|
"""
|
||
|
|
||
|
from __future__ import with_statement
|
||
|
|
||
|
__version__ = '0.3.5'
|
||
|
|
||
|
import sys
|
||
|
|
||
|
from functools import partial, wraps
|
||
|
from collections import deque
|
||
|
|
||
|
from collections import namedtuple
|
||
|
|
||
|
from flask import g, session, current_app, abort, request
|
||
|
from flask.signals import Namespace
|
||
|
|
||
|
PY3 = sys.version_info[0] == 3
|
||
|
|
||
|
signals = Namespace()
|
||
|
|
||
|
|
||
|
identity_changed = signals.signal('identity-changed', doc="""
|
||
|
Signal sent when the identity for a request has been changed.
|
||
|
|
||
|
Actual name: ``identity-changed``
|
||
|
|
||
|
Authentication providers should send this signal when authentication has been
|
||
|
successfully performed. Flask-Principal connects to this signal and
|
||
|
causes the identity to be saved in the session.
|
||
|
|
||
|
For example::
|
||
|
|
||
|
from flaskext.principal import Identity, identity_changed
|
||
|
|
||
|
def login_view(req):
|
||
|
username = req.form.get('username')
|
||
|
# check the credentials
|
||
|
identity_changed.send(app, identity=Identity(username))
|
||
|
""")
|
||
|
|
||
|
|
||
|
identity_loaded = signals.signal('identity-loaded', doc="""
|
||
|
Signal sent when the identity has been initialised for a request.
|
||
|
|
||
|
Actual name: ``identity-loaded``
|
||
|
|
||
|
Identity information providers should connect to this signal to perform two
|
||
|
major activities:
|
||
|
|
||
|
1. Populate the identity object with the necessary authorization provisions.
|
||
|
2. Load any additional user information.
|
||
|
|
||
|
For example::
|
||
|
|
||
|
from flaskext.principal import identity_loaded, RoleNeed, UserNeed
|
||
|
|
||
|
@identity_loaded.connect
|
||
|
def on_identity_loaded(sender, identity):
|
||
|
# Get the user information from the db
|
||
|
user = db.get(identity.name)
|
||
|
# Update the roles that a user can provide
|
||
|
for role in user.roles:
|
||
|
identity.provides.add(RoleNeed(role.name))
|
||
|
# Save the user somewhere so we only look it up once
|
||
|
identity.user = user
|
||
|
""")
|
||
|
|
||
|
|
||
|
Need = namedtuple('Need', ['method', 'value'])
|
||
|
"""A required need
|
||
|
|
||
|
This is just a named tuple, and practically any tuple will do.
|
||
|
|
||
|
The ``method`` attribute can be used to look up element 0, and the ``value``
|
||
|
attribute can be used to look up element 1.
|
||
|
"""
|
||
|
|
||
|
|
||
|
UserNeed = partial(Need, 'id')
|
||
|
UserNeed.__doc__ = """A need with the method preset to `"id"`."""
|
||
|
|
||
|
|
||
|
RoleNeed = partial(Need, 'role')
|
||
|
RoleNeed.__doc__ = """A need with the method preset to `"role"`."""
|
||
|
|
||
|
|
||
|
TypeNeed = partial(Need, 'type')
|
||
|
TypeNeed.__doc__ = """A need with the method preset to `"type"`."""
|
||
|
|
||
|
|
||
|
ActionNeed = partial(Need, 'action')
|
||
|
ActionNeed.__doc__ = """A need with the method preset to `"action"`."""
|
||
|
|
||
|
|
||
|
ItemNeed = namedtuple('ItemNeed', ['method', 'value', 'type'])
|
||
|
"""A required item need
|
||
|
|
||
|
An item need is just a named tuple, and practically any tuple will do. In
|
||
|
addition to other Needs, there is a type, for example this could be specified
|
||
|
as::
|
||
|
|
||
|
ItemNeed('update', 27, 'posts')
|
||
|
('update', 27, 'posts') # or like this
|
||
|
|
||
|
And that might describe the permission to update a particular blog post. In
|
||
|
reality, the developer is free to choose whatever convention the permissions
|
||
|
are.
|
||
|
"""
|
||
|
|
||
|
|
||
|
class PermissionDenied(RuntimeError):
|
||
|
"""Permission denied to the resource"""
|
||
|
|
||
|
|
||
|
class Identity(object):
|
||
|
"""Represent the user's identity.
|
||
|
|
||
|
:param id: The user id
|
||
|
:param auth_type: The authentication type used to confirm the user's
|
||
|
identity.
|
||
|
|
||
|
The identity is used to represent the user's identity in the system. This
|
||
|
object is created on login, or on the start of the request as loaded from
|
||
|
the user's session.
|
||
|
|
||
|
Once loaded it is sent using the `identity-loaded` signal, and should be
|
||
|
populated with additional required information.
|
||
|
|
||
|
Needs that are provided by this identity should be added to the `provides`
|
||
|
set after loading.
|
||
|
"""
|
||
|
def __init__(self, id, auth_type=None):
|
||
|
self.id = id
|
||
|
self.auth_type = auth_type
|
||
|
self.provides = set()
|
||
|
|
||
|
def can(self, permission):
|
||
|
"""Whether the identity has access to the permission.
|
||
|
|
||
|
:param permission: The permission to test provision for.
|
||
|
"""
|
||
|
return permission.allows(self)
|
||
|
|
||
|
def __repr__(self):
|
||
|
return '<{0} id="{1}" auth_type="{2}" provides={3}>'.format(
|
||
|
self.__class__.__name__, self.id, self.auth_type, self.provides
|
||
|
)
|
||
|
|
||
|
|
||
|
class AnonymousIdentity(Identity):
|
||
|
"""An anonymous identity"""
|
||
|
|
||
|
def __init__(self):
|
||
|
Identity.__init__(self, None)
|
||
|
|
||
|
|
||
|
class IdentityContext(object):
|
||
|
"""The context of an identity for a permission.
|
||
|
|
||
|
.. note:: The principal is usually created by the flaskext.Permission.require method
|
||
|
call for normal use-cases.
|
||
|
|
||
|
The principal behaves as either a context manager or a decorator. The
|
||
|
permission is checked for provision in the identity, and if available the
|
||
|
flow is continued (context manager) or the function is executed (decorator).
|
||
|
"""
|
||
|
|
||
|
def __init__(self, permission, http_exception=None):
|
||
|
self.permission = permission
|
||
|
self.http_exception = http_exception
|
||
|
"""The permission of this principal
|
||
|
"""
|
||
|
|
||
|
@property
|
||
|
def identity(self):
|
||
|
"""The identity of this principal
|
||
|
"""
|
||
|
return g.identity
|
||
|
|
||
|
def can(self):
|
||
|
"""Whether the identity has access to the permission
|
||
|
"""
|
||
|
return self.identity.can(self.permission)
|
||
|
|
||
|
def __call__(self, f):
|
||
|
@wraps(f)
|
||
|
def _decorated(*args, **kw):
|
||
|
with self:
|
||
|
rv = f(*args, **kw)
|
||
|
return rv
|
||
|
return _decorated
|
||
|
|
||
|
def __enter__(self):
|
||
|
# check the permission here
|
||
|
if not self.can():
|
||
|
if self.http_exception:
|
||
|
abort(self.http_exception, self.permission)
|
||
|
raise PermissionDenied(self.permission)
|
||
|
|
||
|
def __exit__(self, *args):
|
||
|
return False
|
||
|
|
||
|
|
||
|
class Permission(object):
|
||
|
"""Represents needs, any of which must be present to access a resource
|
||
|
|
||
|
:param needs: The needs for this permission
|
||
|
"""
|
||
|
def __init__(self, *needs):
|
||
|
"""A set of needs, any of which must be present in an identity to have
|
||
|
access.
|
||
|
"""
|
||
|
|
||
|
self.needs = set(needs)
|
||
|
self.excludes = set()
|
||
|
|
||
|
def _bool(self):
|
||
|
return bool(self.can())
|
||
|
|
||
|
def __nonzero__(self):
|
||
|
"""Equivalent to ``self.can()``.
|
||
|
"""
|
||
|
return self._bool()
|
||
|
|
||
|
def __bool__(self):
|
||
|
"""Equivalent to ``self.can()``.
|
||
|
"""
|
||
|
return self._bool()
|
||
|
|
||
|
def __and__(self, other):
|
||
|
"""Does the same thing as ``self.union(other)``
|
||
|
"""
|
||
|
return self.union(other)
|
||
|
|
||
|
def __or__(self, other):
|
||
|
"""Does the same thing as ``self.difference(other)``
|
||
|
"""
|
||
|
return self.difference(other)
|
||
|
|
||
|
def __contains__(self, other):
|
||
|
"""Does the same thing as ``other.issubset(self)``.
|
||
|
"""
|
||
|
return other.issubset(self)
|
||
|
|
||
|
def __repr__(self):
|
||
|
return '<{0} needs={1} excludes={2}>'.format(
|
||
|
self.__class__.__name__, self.needs, self.excludes
|
||
|
)
|
||
|
|
||
|
def require(self, http_exception=None):
|
||
|
"""Create a principal for this permission.
|
||
|
|
||
|
The principal may be used as a context manager, or a decroator.
|
||
|
|
||
|
If ``http_exception`` is passed then ``abort()`` will be called
|
||
|
with the HTTP exception code. Otherwise a ``PermissionDenied``
|
||
|
exception will be raised if the identity does not meet the
|
||
|
requirements.
|
||
|
|
||
|
:param http_exception: the HTTP exception code (403, 401 etc)
|
||
|
"""
|
||
|
return IdentityContext(self, http_exception)
|
||
|
|
||
|
def test(self, http_exception=None):
|
||
|
"""
|
||
|
Checks if permission available and raises relevant exception
|
||
|
if not. This is useful if you just want to check permission
|
||
|
without wrapping everything in a require() block.
|
||
|
|
||
|
This is equivalent to::
|
||
|
|
||
|
with permission.require():
|
||
|
pass
|
||
|
"""
|
||
|
|
||
|
with self.require(http_exception):
|
||
|
pass
|
||
|
|
||
|
def reverse(self):
|
||
|
"""
|
||
|
Returns reverse of current state (needs->excludes, excludes->needs)
|
||
|
"""
|
||
|
|
||
|
p = Permission()
|
||
|
p.needs.update(self.excludes)
|
||
|
p.excludes.update(self.needs)
|
||
|
return p
|
||
|
|
||
|
def union(self, other):
|
||
|
"""Create a new permission with the requirements of the union of this
|
||
|
and other.
|
||
|
|
||
|
:param other: The other permission
|
||
|
"""
|
||
|
p = Permission(*self.needs.union(other.needs))
|
||
|
p.excludes.update(self.excludes.union(other.excludes))
|
||
|
return p
|
||
|
|
||
|
def difference(self, other):
|
||
|
"""Create a new permission consisting of requirements in this
|
||
|
permission and not in the other.
|
||
|
"""
|
||
|
|
||
|
p = Permission(*self.needs.difference(other.needs))
|
||
|
p.excludes.update(self.excludes.difference(other.excludes))
|
||
|
return p
|
||
|
|
||
|
def issubset(self, other):
|
||
|
"""Whether this permission needs are a subset of another
|
||
|
|
||
|
:param other: The other permission
|
||
|
"""
|
||
|
return (
|
||
|
self.needs.issubset(other.needs) and
|
||
|
self.excludes.issubset(other.excludes)
|
||
|
)
|
||
|
|
||
|
def allows(self, identity):
|
||
|
"""Whether the identity can access this permission.
|
||
|
|
||
|
:param identity: The identity
|
||
|
"""
|
||
|
if self.needs and not self.needs.intersection(identity.provides):
|
||
|
return False
|
||
|
|
||
|
if self.excludes and self.excludes.intersection(identity.provides):
|
||
|
return False
|
||
|
|
||
|
return True
|
||
|
|
||
|
def can(self):
|
||
|
"""Whether the required context for this permission has access
|
||
|
|
||
|
This creates an identity context and tests whether it can access this
|
||
|
permission
|
||
|
"""
|
||
|
return self.require().can()
|
||
|
|
||
|
|
||
|
class Denial(Permission):
|
||
|
"""
|
||
|
Shortcut class for passing excluded needs.
|
||
|
"""
|
||
|
|
||
|
def __init__(self, *excludes):
|
||
|
self.excludes = set(excludes)
|
||
|
self.needs = set()
|
||
|
|
||
|
|
||
|
def session_identity_loader():
|
||
|
if 'identity.id' in session and 'identity.auth_type' in session:
|
||
|
identity = Identity(session['identity.id'],
|
||
|
session['identity.auth_type'])
|
||
|
return identity
|
||
|
|
||
|
|
||
|
def session_identity_saver(identity):
|
||
|
session['identity.id'] = identity.id
|
||
|
session['identity.auth_type'] = identity.auth_type
|
||
|
session.modified = True
|
||
|
|
||
|
|
||
|
class Principal(object):
|
||
|
"""Principal extension
|
||
|
|
||
|
:param app: The flask application to extend
|
||
|
:param use_sessions: Whether to use sessions to extract and store
|
||
|
identification.
|
||
|
:param skip_static: Whether to ignore static endpoints.
|
||
|
"""
|
||
|
def __init__(self, app=None, use_sessions=True, skip_static=False):
|
||
|
self.identity_loaders = deque()
|
||
|
self.identity_savers = deque()
|
||
|
# XXX This will probably vanish for a better API
|
||
|
self.use_sessions = use_sessions
|
||
|
self.skip_static = skip_static
|
||
|
|
||
|
if app is not None:
|
||
|
self.init_app(app)
|
||
|
|
||
|
def _init_app(self, app):
|
||
|
from warnings import warn
|
||
|
warn(DeprecationWarning(
|
||
|
'_init_app is deprecated, use the new init_app '
|
||
|
'method instead.'), stacklevel=1
|
||
|
)
|
||
|
self.init_app(app)
|
||
|
|
||
|
def init_app(self, app):
|
||
|
if hasattr(app, 'static_url_path'):
|
||
|
self._static_path = app.static_url_path
|
||
|
else:
|
||
|
self._static_path = app.static_path
|
||
|
|
||
|
app.before_request(self._on_before_request)
|
||
|
identity_changed.connect(self._on_identity_changed, app)
|
||
|
|
||
|
if self.use_sessions:
|
||
|
self.identity_loader(session_identity_loader)
|
||
|
self.identity_saver(session_identity_saver)
|
||
|
|
||
|
def set_identity(self, identity):
|
||
|
"""Set the current identity.
|
||
|
|
||
|
:param identity: The identity to set
|
||
|
"""
|
||
|
|
||
|
self._set_thread_identity(identity)
|
||
|
for saver in self.identity_savers:
|
||
|
saver(identity)
|
||
|
|
||
|
def identity_loader(self, f):
|
||
|
"""Decorator to define a function as an identity loader.
|
||
|
|
||
|
An identity loader function is called before request to find any
|
||
|
provided identities. The first found identity is used to load from.
|
||
|
|
||
|
For example::
|
||
|
|
||
|
app = Flask(__name__)
|
||
|
|
||
|
principals = Principal(app)
|
||
|
|
||
|
@principals.identity_loader
|
||
|
def load_identity_from_weird_usecase():
|
||
|
return Identity('ali')
|
||
|
"""
|
||
|
self.identity_loaders.appendleft(f)
|
||
|
return f
|
||
|
|
||
|
def identity_saver(self, f):
|
||
|
"""Decorator to define a function as an identity saver.
|
||
|
|
||
|
An identity loader saver is called when the identity is set to persist
|
||
|
it for the next request.
|
||
|
|
||
|
For example::
|
||
|
|
||
|
app = Flask(__name__)
|
||
|
|
||
|
principals = Principal(app)
|
||
|
|
||
|
@principals.identity_saver
|
||
|
def save_identity_to_weird_usecase(identity):
|
||
|
my_special_cookie['identity'] = identity
|
||
|
"""
|
||
|
self.identity_savers.appendleft(f)
|
||
|
return f
|
||
|
|
||
|
def _set_thread_identity(self, identity):
|
||
|
g.identity = identity
|
||
|
identity_loaded.send(current_app._get_current_object(),
|
||
|
identity=identity)
|
||
|
|
||
|
def _on_identity_changed(self, app, identity):
|
||
|
if self._is_static_route():
|
||
|
return
|
||
|
|
||
|
self.set_identity(identity)
|
||
|
|
||
|
def _on_before_request(self):
|
||
|
if self._is_static_route():
|
||
|
return
|
||
|
|
||
|
g.identity = AnonymousIdentity()
|
||
|
for loader in self.identity_loaders:
|
||
|
identity = loader()
|
||
|
if identity is not None:
|
||
|
self.set_identity(identity)
|
||
|
return
|
||
|
|
||
|
def _is_static_route(self):
|
||
|
return (
|
||
|
self.skip_static and
|
||
|
(self._static_path and request.path.startswith(self._static_path))
|
||
|
)
|