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zope.pluggableauth 2.3.0

Pluggable Authentication Utility

zope.pluggableauth

Based on zope.authentication, this package provides a flexible and pluggable authentication utility, and provides a number of common plugins.

Pluggable-Authentication Utility

The Pluggable-Authentication Utility (PAU) provides a framework for authenticating principals and associating information with them. It uses plugins and subscribers to get its work done.

For a pluggable-authentication utility to be used, it should be registered as a utility providing the zope.authentication.interfaces.IAuthentication interface.

Authentication

The primary job of PAU is to authenticate principals. It uses two types of plug-ins in its work:

  • Credentials Plugins
  • Authenticator Plugins

Credentials plugins are responsible for extracting user credentials from a request. A credentials plugin may in some cases issue a ‘challenge’ to obtain credentials. For example, a ‘session’ credentials plugin reads credentials from a session (the “extraction”). If it cannot find credentials, it will redirect the user to a login form in order to provide them (the “challenge”).

Authenticator plugins are responsible for authenticating the credentials extracted by a credentials plugin. They are also typically able to create principal objects for credentials they successfully authenticate.

Given a request object, the PAU returns a principal object, if it can. The PAU does this by first iterating through its credentials plugins to obtain a set of credentials. If it gets credentials, it iterates through its authenticator plugins to authenticate them.

If an authenticator succeeds in authenticating a set of credentials, the PAU uses the authenticator to create a principal corresponding to the credentials. The authenticator notifies subscribers if an authenticated principal is created. Subscribers are responsible for adding data, especially groups, to the principal. Typically, if a subscriber adds data, it should also add corresponding interface declarations.

Simple Credentials Plugin

To illustrate, we’ll create a simple credentials plugin:

>>> from zope import interface
>>> from zope.pluggableauth.authentication import interfaces
>>> @interface.implementer(interfaces.ICredentialsPlugin)
... class MyCredentialsPlugin(object):
...
...     def extractCredentials(self, request):
...         return request.get('credentials')
...
...     def challenge(self, request):
...         pass # challenge is a no-op for this plugin
...
...     def logout(self, request):
...         pass # logout is a no-op for this plugin

As a plugin, MyCredentialsPlugin needs to be registered as a named utility:

>>> myCredentialsPlugin = MyCredentialsPlugin()
>>> provideUtility(myCredentialsPlugin, name='My Credentials Plugin')

Simple Authenticator Plugin

Next we’ll create a simple authenticator plugin. For our plugin, we’ll need an implementation of IPrincipalInfo:

>>> @interface.implementer(interfaces.IPrincipalInfo)
... class PrincipalInfo(object):
...
...     def __init__(self, id, title, description):
...         self.id = id
...         self.title = title
...         self.description = description
...
...     def __repr__(self):
...         return 'PrincipalInfo(%r)' % self.id

Our authenticator uses this type when it creates a principal info:

>>> @interface.implementer(interfaces.IAuthenticatorPlugin)
... class MyAuthenticatorPlugin(object):
...
...     def authenticateCredentials(self, credentials):
...         if credentials == 'secretcode':
...             return PrincipalInfo('bob', 'Bob', '')
...
...     def principalInfo(self, id):
...         pass # plugin not currently supporting search

As with the credentials plugin, the authenticator plugin must be registered as a named utility:

>>> myAuthenticatorPlugin = MyAuthenticatorPlugin()
>>> provideUtility(myAuthenticatorPlugin, name='My Authenticator Plugin')

Configuring a PAU

Finally, we’ll create the PAU itself:

>>> from zope.pluggableauth import authentication
>>> pau = authentication.PluggableAuthentication('xyz_')

and configure it with the two plugins:

>>> pau.credentialsPlugins = ('My Credentials Plugin', )
>>> pau.authenticatorPlugins = ('My Authenticator Plugin', )

Using the PAU to Authenticate

>>> from zope.pluggableauth.factories import AuthenticatedPrincipalFactory
>>> provideAdapter(AuthenticatedPrincipalFactory)

We can now use the PAU to authenticate a sample request:

>>> from zope.publisher.browser import TestRequest
>>> print(pau.authenticate(TestRequest()))
None

In this case, we cannot authenticate an empty request. In the same way, we will not be able to authenticate a request with the wrong credentials:

>>> print(pau.authenticate(TestRequest(credentials='let me in!')))
None

However, if we provide the proper credentials:

>>> request = TestRequest(credentials='secretcode')
>>> principal = pau.authenticate(request)
>>> principal
Principal('xyz_bob')

we get an authenticated principal.

Multiple Authenticator Plugins

The PAU works with multiple authenticator plugins. It uses each plugin, in the order specified in the PAU’s authenticatorPlugins attribute, to authenticate a set of credentials.

To illustrate, we’ll create another authenticator:

>>> class MyAuthenticatorPlugin2(MyAuthenticatorPlugin):
...
...     def authenticateCredentials(self, credentials):
...         if credentials == 'secretcode':
...             return PrincipalInfo('black', 'Black Spy', '')
...         elif credentials == 'hiddenkey':
...             return PrincipalInfo('white', 'White Spy', '')
>>> provideUtility(MyAuthenticatorPlugin2(), name='My Authenticator Plugin 2')

If we put it before the original authenticator:

>>> pau.authenticatorPlugins = (
...     'My Authenticator Plugin 2',
...     'My Authenticator Plugin')

Then it will be given the first opportunity to authenticate a request:

>>> pau.authenticate(TestRequest(credentials='secretcode'))
Principal('xyz_black')

If neither plugins can authenticate, pau returns None:

>>> print(pau.authenticate(TestRequest(credentials='let me in!!')))
None

When we change the order of the authenticator plugins:

>>> pau.authenticatorPlugins = (
...     'My Authenticator Plugin',
...     'My Authenticator Plugin 2')

we see that our original plugin is now acting first:

>>> pau.authenticate(TestRequest(credentials='secretcode'))
Principal('xyz_bob')

The second plugin, however, gets a chance to authenticate if first does not:

>>> pau.authenticate(TestRequest(credentials='hiddenkey'))
Principal('xyz_white')

Multiple Credentials Plugins

As with with authenticators, we can specify multiple credentials plugins. To illustrate, we’ll create a credentials plugin that extracts credentials from a request form:

>>> @interface.implementer(interfaces.ICredentialsPlugin)
... class FormCredentialsPlugin:
...
...     def extractCredentials(self, request):
...         return request.form.get('my_credentials')
...
...     def challenge(self, request):
...         pass
...
...     def logout(request):
...         pass
>>> provideUtility(FormCredentialsPlugin(),
...                name='Form Credentials Plugin')

and insert the new credentials plugin before the existing plugin:

>>> pau.credentialsPlugins = (
...     'Form Credentials Plugin',
...     'My Credentials Plugin')

The PAU will use each plugin in order to try and obtain credentials from a request:

>>> pau.authenticate(TestRequest(credentials='secretcode',
...                              form={'my_credentials': 'hiddenkey'}))
Principal('xyz_white')

In this case, the first credentials plugin succeeded in getting credentials from the form and the second authenticator was able to authenticate the credentials. Specifically, the PAU went through these steps:

  • Get credentials using ‘Form Credentials Plugin’
  • Got ‘hiddenkey’ credentials using ‘Form Credentials Plugin’, try to authenticate using ‘My Authenticator Plugin’
  • Failed to authenticate ‘hiddenkey’ with ‘My Authenticator Plugin’, try ‘My Authenticator Plugin 2’
  • Succeeded in authenticating with ‘My Authenticator Plugin 2’

Let’s try a different scenario:

>>> pau.authenticate(TestRequest(credentials='secretcode'))
Principal('xyz_bob')

In this case, the PAU went through these steps:

- Get credentials using 'Form Credentials Plugin'
  • Failed to get credentials using ‘Form Credentials Plugin’, try ‘My Credentials Plugin’
  • Got ‘scecretcode’ credentials using ‘My Credentials Plugin’, try to authenticate using ‘My Authenticator Plugin’
  • Succeeded in authenticating with ‘My Authenticator Plugin’

Let’s try a slightly more complex scenario:

>>> pau.authenticate(TestRequest(credentials='hiddenkey',
...                              form={'my_credentials': 'bogusvalue'}))
Principal('xyz_white')

This highlights PAU’s ability to use multiple plugins for authentication:

  • Get credentials using ‘Form Credentials Plugin’
  • Got ‘bogusvalue’ credentials using ‘Form Credentials Plugin’, try to authenticate using ‘My Authenticator Plugin’
  • Failed to authenticate ‘boguskey’ with ‘My Authenticator Plugin’, try ‘My Authenticator Plugin 2’
  • Failed to authenticate ‘boguskey’ with ‘My Authenticator Plugin 2’ – there are no more authenticators to try, so lets try the next credentials plugin for some new credentials
  • Get credentials using ‘My Credentials Plugin’
  • Got ‘hiddenkey’ credentials using ‘My Credentials Plugin’, try to authenticate using ‘My Authenticator Plugin’
  • Failed to authenticate ‘hiddenkey’ using ‘My Authenticator Plugin’, try ‘My Authenticator Plugin 2’
  • Succeeded in authenticating with ‘My Authenticator Plugin 2’ (shouts and cheers!)

Multiple Authenticator Plugins

As with the other operations we’ve seen, the PAU uses multiple plugins to find a principal. If the first authenticator plugin can’t find the requested principal, the next plugin is used, and so on.

>>> @interface.implementer(interfaces.IAuthenticatorPlugin)
... class AnotherAuthenticatorPlugin:
...
...     def __init__(self):
...         self.infos = {}
...         self.ids = {}
...
...     def principalInfo(self, id):
...         return self.infos.get(id)
...
...     def authenticateCredentials(self, credentials):
...         id = self.ids.get(credentials)
...         if id is not None:
...             return self.infos[id]
...
...     def add(self, id, title, description, credentials):
...         self.infos[id] = PrincipalInfo(id, title, description)
...         self.ids[credentials] = id

To illustrate, we’ll create and register two authenticators:

>>> authenticator1 = AnotherAuthenticatorPlugin()
>>> provideUtility(authenticator1, name='Authentication Plugin 1')
>>> authenticator2 = AnotherAuthenticatorPlugin()
>>> provideUtility(authenticator2, name='Authentication Plugin 2')

and add a principal to them:

>>> authenticator1.add('bob', 'Bob', 'A nice guy', 'b0b')
>>> authenticator1.add('white', 'White Spy', 'Sneaky', 'deathtoblack')
>>> authenticator2.add('black', 'Black Spy', 'Also sneaky', 'deathtowhite')

When we configure the PAU to use both searchable authenticators (note the order):

>>> pau.authenticatorPlugins = (
...     'Authentication Plugin 2',
...     'Authentication Plugin 1')

we register the factories for our principals:

>>> from zope.pluggableauth.factories import FoundPrincipalFactory
>>> provideAdapter(FoundPrincipalFactory)

we see how the PAU uses both plugins:

>>> pau.getPrincipal('xyz_white')
Principal('xyz_white')
>>> pau.getPrincipal('xyz_black')
Principal('xyz_black')

If more than one plugin know about the same principal ID, the first plugin is used and the remaining are not delegated to. To illustrate, we’ll add another principal with the same ID as an existing principal:

>>> authenticator2.add('white', 'White Rider', '', 'r1der')
>>> pau.getPrincipal('xyz_white').title
'White Rider'

If we change the order of the plugins:

>>> pau.authenticatorPlugins = (
...     'Authentication Plugin 1',
...     'Authentication Plugin 2')

we get a different principal for ID ‘white’:

>>> pau.getPrincipal('xyz_white').title
'White Spy'

Issuing a Challenge

Part of PAU’s IAuthentication contract is to challenge the user for credentials when its ‘unauthorized’ method is called. The need for this functionality is driven by the following use case:

  • A user attempts to perform an operation he is not authorized to perform.
  • A handler responds to the unauthorized error by calling IAuthentication ‘unauthorized’.
  • The authentication component (in our case, a PAU) issues a challenge to the user to collect new credentials (typically in the form of logging in as a new user).

The PAU handles the credentials challenge by delegating to its credentials plugins.

Currently, the PAU is configured with the credentials plugins that don’t perform any action when asked to challenge (see above the ‘challenge’ methods).

To illustrate challenges, we’ll subclass an existing credentials plugin and do something in its ‘challenge’:

>>> class LoginFormCredentialsPlugin(FormCredentialsPlugin):
...
...     def __init__(self, loginForm):
...         self.loginForm = loginForm
...
...     def challenge(self, request):
...         request.response.redirect(self.loginForm)
...         return True

This plugin handles a challenge by redirecting the response to a login form. It returns True to signal to the PAU that it handled the challenge.

We will now create and register a couple of these plugins:

>>> provideUtility(LoginFormCredentialsPlugin('simplelogin.html'),
...                name='Simple Login Form Plugin')
>>> provideUtility(LoginFormCredentialsPlugin('advancedlogin.html'),
...                name='Advanced Login Form Plugin')

and configure the PAU to use them:

>>> pau.credentialsPlugins = (
...     'Simple Login Form Plugin',
...     'Advanced Login Form Plugin')

Now when we call ‘unauthorized’ on the PAU:

>>> request = TestRequest()
>>> pau.unauthorized(id=None, request=request)

we see that the user is redirected to the simple login form:

>>> request.response.getStatus()
302
>>> request.response.getHeader('location')
'simplelogin.html'

We can change the challenge policy by reordering the plugins:

>>> pau.credentialsPlugins = (
...     'Advanced Login Form Plugin',
...     'Simple Login Form Plugin')

Now when we call ‘unauthorized’:

>>> request = TestRequest()
>>> pau.unauthorized(id=None, request=request)

the advanced plugin is used because it’s first:

>>> request.response.getStatus()
302
>>> request.response.getHeader('location')
'advancedlogin.html'

Challenge Protocols

Sometimes, we want multiple challengers to work together. For example, the HTTP specification allows multiple challenges to be issued in a response. A challenge plugin can provide a challengeProtocol attribute that effectively groups related plugins together for challenging. If a plugin returns True from its challenge and provides a non-None challengeProtocol, subsequent plugins in the credentialsPlugins list that have the same challenge protocol will also be used to challenge.

Without a challengeProtocol, only the first plugin to succeed in a challenge will be used.

Let’s look at an example. We’ll define a new plugin that specifies an ‘X-Challenge’ protocol:

>>> class XChallengeCredentialsPlugin(FormCredentialsPlugin):
...
...     challengeProtocol = 'X-Challenge'
...
...     def __init__(self, challengeValue):
...         self.challengeValue = challengeValue
...
...     def challenge(self, request):
...         value = self.challengeValue
...         existing = request.response.getHeader('X-Challenge', '')
...         if existing:
...             value += ' ' + existing
...         request.response.setHeader('X-Challenge', value)
...         return True

and register a couple instances as utilities:

>>> provideUtility(XChallengeCredentialsPlugin('basic'),
...                name='Basic X-Challenge Plugin')
>>> provideUtility(XChallengeCredentialsPlugin('advanced'),
...                name='Advanced X-Challenge Plugin')

When we use both plugins with the PAU:

>>> pau.credentialsPlugins = (
...     'Basic X-Challenge Plugin',
...     'Advanced X-Challenge Plugin')

and call ‘unauthorized’:

>>> request = TestRequest()
>>> pau.unauthorized(None, request)

we see that both plugins participate in the challenge, rather than just the first plugin:

>>> request.response.getHeader('X-Challenge')
'advanced basic'

Pluggable-Authentication Prefixes

Principal ids are required to be unique system wide. Plugins will often provide options for providing id prefixes, so that different sets of plugins provide unique ids within a PAU. If there are multiple pluggable-authentication utilities in a system, it’s a good idea to give each PAU a unique prefix, so that principal ids from different PAUs don’t conflict. We can provide a prefix when a PAU is created:

>>> pau = authentication.PluggableAuthentication('mypau_')
>>> pau.credentialsPlugins = ('My Credentials Plugin', )
>>> pau.authenticatorPlugins = ('My Authenticator Plugin', )

When we create a request and try to authenticate:

>>> pau.authenticate(TestRequest(credentials='secretcode'))
Principal('mypau_bob')

Note that now, our principal’s id has the pluggable-authentication utility prefix.

We can still lookup a principal, as long as we supply the prefix:

>> pau.getPrincipal('mypas_42')
Principal('mypas_42', "{'domain': 42}")

>> pau.getPrincipal('mypas_41')
OddPrincipal('mypas_41', "{'int': 41}")

Principal Folder

Principal folders contain principal-information objects that contain principal information. We create an internal principal using the InternalPrincipal class:

>>> from zope.pluggableauth.plugins.principalfolder import InternalPrincipal
>>> p1 = InternalPrincipal('login1', '123', "Principal 1",
...     passwordManagerName="SHA1")
>>> p2 = InternalPrincipal('login2', '456', "The Other One")

and add them to a principal folder:

>>> from zope.pluggableauth.plugins.principalfolder import PrincipalFolder
>>> principals = PrincipalFolder(u'principal.')
>>> principals['p1'] = p1
>>> principals['p2'] = p2

Authentication

Principal folders provide the IAuthenticatorPlugin interface. When we provide suitable credentials:

>>> from pprint import pprint
>>> principals.authenticateCredentials({'login': 'login1', 'password': '123'})
PrincipalInfo(u'principal.p1')

We get back a principal id and supplementary information, including the principal title and description. Note that the principal id is a concatenation of the principal-folder prefix and the name of the principal-information object within the folder.

None is returned if the credentials are invalid:

>>> principals.authenticateCredentials({'login': 'login1',
...                                     'password': '1234'})
>>> principals.authenticateCredentials(42)

Changing credentials

Credentials can be changed by modifying principal-information objects:

>>> p1.login = 'bob'
>>> p1.password = 'eek'
>>> principals.authenticateCredentials({'login': 'bob', 'password': 'eek'})
PrincipalInfo(u'principal.p1')
>>> principals.authenticateCredentials({'login': 'login1',
...                                     'password': 'eek'})
>>> principals.authenticateCredentials({'login': 'bob',
...                                     'password': '123'})

It is an error to try to pick a login name that is already taken:

>>> p1.login = 'login2'
Traceback (most recent call last):
...
ValueError: Principal Login already taken!

If such an attempt is made, the data are unchanged:

>>> principals.authenticateCredentials({'login': 'bob', 'password': 'eek'})
PrincipalInfo(u'principal.p1')

Removing principals

Of course, if a principal is removed, we can no-longer authenticate it:

>>> del principals['p1']
>>> principals.authenticateCredentials({'login': 'bob',
...                                     'password': 'eek'})

Group Folders

Group folders provide support for groups information stored in the ZODB. They are persistent, and must be contained within the PAUs that use them.

Like other principals, groups are created when they are needed.

Group folders contain group-information objects that contain group information. We create group information using the GroupInformation class:

>>> import zope.pluggableauth.plugins.groupfolder
>>> g1 = zope.pluggableauth.plugins.groupfolder.GroupInformation("Group 1")
>>> groups = zope.pluggableauth.plugins.groupfolder.GroupFolder('group.')
>>> groups['g1'] = g1

Note that when group-info is added, a GroupAdded event is generated:

>>> from zope.pluggableauth import interfaces
>>> from zope.component.eventtesting import getEvents
>>> getEvents(interfaces.IGroupAdded)
[<GroupAdded 'group.g1'>]

Groups are defined with respect to an authentication service. Groups must be accessible via an authentication service and can contain principals accessible via an authentication service.

To illustrate the group interaction with the authentication service, we’ll create a sample authentication service:

>>> from zope import interface
>>> from zope.authentication.interfaces import IAuthentication
>>> from zope.authentication.interfaces import PrincipalLookupError
>>> from zope.security.interfaces import IGroupAwarePrincipal
>>> from zope.pluggableauth.plugins.groupfolder import setGroupsForPrincipal
>>> @interface.implementer(IGroupAwarePrincipal)
... class Principal:
...     def __init__(self, id, title='', description=''):
...         self.id, self.title, self.description = id, title, description
...         self.groups = []
>>> class PrincipalCreatedEvent:
...     def __init__(self, authentication, principal):
...         self.authentication = authentication
...         self.principal = principal
>>> from zope.pluggableauth.plugins import principalfolder
>>> @interface.implementer(IAuthentication)
... class Principals:
...     def __init__(self, groups, prefix='auth.'):
...         self.prefix = prefix
...         self.principals = {
...            'p1': principalfolder.PrincipalInfo('p1', '', '', ''),
...            'p2': principalfolder.PrincipalInfo('p2', '', '', ''),
...            'p3': principalfolder.PrincipalInfo('p3', '', '', ''),
...            'p4': principalfolder.PrincipalInfo('p4', '', '', ''),
...            }
...         self.groups = groups
...         groups.__parent__ = self
...
...     def getAuthenticatorPlugins(self):
...         return [('principals', self.principals), ('groups', self.groups)]
...
...     def getPrincipal(self, id):
...         if not id.startswith(self.prefix):
...             raise PrincipalLookupError(id)
...         id = id[len(self.prefix):]
...         info = self.principals.get(id)
...         if info is None:
...             info = self.groups.principalInfo(id)
...             if info is None:
...                raise PrincipalLookupError(id)
...         principal = Principal(self.prefix+info.id,
...                               info.title, info.description)
...         setGroupsForPrincipal(PrincipalCreatedEvent(self, principal))
...         return principal

This class doesn’t really implement the full IAuthentication interface, but it implements the getPrincipal method used by groups. It works very much like the pluggable authentication utility. It creates principals on demand. It calls setGroupsForPrincipal, which is normally called as an event subscriber, when principals are created. In order for setGroupsForPrincipal to find out group folder, we have to register it as a utility:

>>> from zope.pluggableauth.interfaces import IAuthenticatorPlugin
>>> from zope.component import provideUtility
>>> provideUtility(groups, IAuthenticatorPlugin)

We will create and register a new principals utility:

>>> principals = Principals(groups)
>>> provideUtility(principals, IAuthentication)

Now we can set the principals on the group:

>>> g1.principals = ['auth.p1', 'auth.p2']
>>> g1.principals
('auth.p1', 'auth.p2')

Adding principals fires an event.

>>> getEvents(interfaces.IPrincipalsAddedToGroup)[-1]
<PrincipalsAddedToGroup ['auth.p1', 'auth.p2'] u'auth.group.g1'>

We can now look up groups for the principals:

>>> groups.getGroupsForPrincipal('auth.p1')
(u'group.g1',)

Note that the group id is a concatenation of the group-folder prefix and the name of the group-information object within the folder.

If we delete a group:

>>> del groups['g1']

then the groups folder loses the group information for that group’s principals:

>>> groups.getGroupsForPrincipal('auth.p1')
()

but the principal information on the group is unchanged:

>>> g1.principals
('auth.p1', 'auth.p2')

It also fires an event showing that the principals are removed from the group (g1 is group information, not a zope.security.interfaces.IGroup).

>>> getEvents(interfaces.IPrincipalsRemovedFromGroup)[-1]
<PrincipalsRemovedFromGroup ['auth.p1', 'auth.p2'] u'auth.group.g1'>

Adding the group sets the folder principal information. Let’s use a different group name:

>>> groups['G1'] = g1
>>> groups.getGroupsForPrincipal('auth.p1')
(u'group.G1',)

Here we see that the new name is reflected in the group information.

An event is fired, as usual.

>>> getEvents(interfaces.IPrincipalsAddedToGroup)[-1]
<PrincipalsAddedToGroup ['auth.p1', 'auth.p2'] u'auth.group.G1'>

In terms of member events (principals added and removed from groups), we have now seen that events are fired when a group information object is added and when it is removed from a group folder; and we have seen that events are fired when a principal is added to an already-registered group. Events are also fired when a principal is removed from an already-registered group. Let’s quickly see some more examples.

>>> g1.principals = ('auth.p1', 'auth.p3', 'auth.p4')
>>> getEvents(interfaces.IPrincipalsAddedToGroup)[-1]
<PrincipalsAddedToGroup ['auth.p3', 'auth.p4'] u'auth.group.G1'>
>>> getEvents(interfaces.IPrincipalsRemovedFromGroup)[-1]
<PrincipalsRemovedFromGroup ['auth.p2'] u'auth.group.G1'>
>>> g1.principals = ('auth.p1', 'auth.p2')
>>> getEvents(interfaces.IPrincipalsAddedToGroup)[-1]
<PrincipalsAddedToGroup ['auth.p2'] u'auth.group.G1'>
>>> getEvents(interfaces.IPrincipalsRemovedFromGroup)[-1]
<PrincipalsRemovedFromGroup ['auth.p3', 'auth.p4'] u'auth.group.G1'>

Groups can contain groups:

>>> g2 = zope.pluggableauth.plugins.groupfolder.GroupInformation("Group Two")
>>> groups['G2'] = g2
>>> g2.principals = ['auth.group.G1']
>>> groups.getGroupsForPrincipal('auth.group.G1')
(u'group.G2',)
>>> old = getEvents(interfaces.IPrincipalsAddedToGroup)[-1]
>>> old
<PrincipalsAddedToGroup ['auth.group.G1'] u'auth.group.G2'>

Groups cannot contain cycles:

>>> g1.principals = ('auth.p1', 'auth.p2', 'auth.group.G2')
... # doctest: +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
zope.pluggableauth.plugins.groupfolder.GroupCycle: (u'auth.group.G2', [u'auth.group.G2', u'auth.group.G1'])

Trying to do so does not fire an event.

>>> getEvents(interfaces.IPrincipalsAddedToGroup)[-1] is old
True

They need not be hierarchical:

>>> ga = zope.pluggableauth.plugins.groupfolder.GroupInformation("Group A")
>>> groups['GA'] = ga
>>> gb = zope.pluggableauth.plugins.groupfolder.GroupInformation("Group B")
>>> groups['GB'] = gb
>>> gb.principals = ['auth.group.GA']
>>> gc = zope.pluggableauth.plugins.groupfolder.GroupInformation("Group C")
>>> groups['GC'] = gc
>>> gc.principals = ['auth.group.GA']
>>> gd = zope.pluggableauth.plugins.groupfolder.GroupInformation("Group D")
>>> groups['GD'] = gd
>>> gd.principals = ['auth.group.GA', 'auth.group.GB']
>>> ga.principals = ['auth.p1']

Group folders provide a very simple search interface. They perform simple string searches on group titles and descriptions.

>>> list(groups.search({'search': 'grou'})) # doctest: +NORMALIZE_WHITESPACE
[u'group.G1', u'group.G2',
 u'group.GA', u'group.GB', u'group.GC', u'group.GD']
>>> list(groups.search({'search': 'two'}))
[u'group.G2']

They also support batching:

>>> list(groups.search({'search': 'grou'}, 2, 3))
[u'group.GA', u'group.GB', u'group.GC']

If you don’t supply a search key, no results will be returned:

>>> list(groups.search({}))
[]

Identifying groups

The function, setGroupsForPrincipal, is a subscriber to principal-creation events. It adds any group-folder-defined groups to users in those groups:

>>> principal = principals.getPrincipal('auth.p1')
>>> principal.groups
[u'auth.group.G1', u'auth.group.GA']

Of course, this applies to groups too:

>>> principal = principals.getPrincipal('auth.group.G1')
>>> principal.id
'auth.group.G1'
>>> principal.groups
[u'auth.group.G2']

In addition to setting principal groups, the setGroupsForPrincipal function also declares the IGroup interface on groups:

>>> [iface.__name__ for iface in interface.providedBy(principal)]
['IGroup', 'IGroupAwarePrincipal']
>>> [iface.__name__
...  for iface in interface.providedBy(principals.getPrincipal('auth.p1'))]
['IGroupAwarePrincipal']

Special groups

Two special groups, Authenticated, and Everyone may apply to users created by the pluggable-authentication utility. There is a subscriber, specialGroups, that will set these groups on any non-group principals if IAuthenticatedGroup, or IEveryoneGroup utilities are provided.

Lets define a group-aware principal:

>>> import zope.security.interfaces
>>> @interface.implementer(zope.security.interfaces.IGroupAwarePrincipal)
... class GroupAwarePrincipal(Principal):
...     def __init__(self, id):
...         Principal.__init__(self, id)
...         self.groups = []

If we notify the subscriber with this principal, nothing will happen because the groups haven’t been defined:

>>> prin = GroupAwarePrincipal('x')
>>> event = interfaces.FoundPrincipalCreated(42, prin, {})
>>> zope.pluggableauth.plugins.groupfolder.specialGroups(event)
>>> prin.groups
[]

Now, if we define the Everybody group:

>>> import zope.authentication.interfaces
>>> @interface.implementer(zope.authentication.interfaces.IEveryoneGroup)
... class EverybodyGroup(Principal):
...     pass
>>> everybody = EverybodyGroup('all')
>>> provideUtility(everybody, zope.authentication.interfaces.IEveryoneGroup)

Then the group will be added to the principal:

>>> zope.pluggableauth.plugins.groupfolder.specialGroups(event)
>>> prin.groups
['all']

Similarly for the authenticated group:

>>> @interface.implementer(
...         zope.authentication.interfaces.IAuthenticatedGroup)
... class AuthenticatedGroup(Principal):
...     pass
>>> authenticated = AuthenticatedGroup('auth')
>>> provideUtility(authenticated, zope.authentication.interfaces.IAuthenticatedGroup)

Then the group will be added to the principal:

>>> prin.groups = []
>>> zope.pluggableauth.plugins.groupfolder.specialGroups(event)
>>> prin.groups.sort()
>>> prin.groups
['all', 'auth']

These groups are only added to non-group principals:

>>> prin.groups = []
>>> interface.directlyProvides(prin, zope.security.interfaces.IGroup)
>>> zope.pluggableauth.plugins.groupfolder.specialGroups(event)
>>> prin.groups
[]

And they are only added to group aware principals:

>>> @interface.implementer(zope.security.interfaces.IPrincipal)
... class SolitaryPrincipal:
...     id = title = description = ''
>>> event = interfaces.FoundPrincipalCreated(42, SolitaryPrincipal(), {})
>>> zope.pluggableauth.plugins.groupfolder.specialGroups(event)
>>> prin.groups
[]

Member-aware groups

The groupfolder includes a subscriber that gives group principals the zope.security.interfaces.IGroupAware interface and an implementation thereof. This allows groups to be able to get and set their members.

Given an info object and a group…

>>> @interface.implementer(
...         zope.pluggableauth.plugins.groupfolder.IGroupInformation)
... class DemoGroupInformation(object):
...     def __init__(self, title, description, principals):
...         self.title = title
...         self.description = description
...         self.principals = principals
...
>>> i = DemoGroupInformation(
...     'Managers', 'Taskmasters', ('joe', 'jane'))
...
>>> info = zope.pluggableauth.plugins.groupfolder.GroupInfo(
...     'groups.managers', i)
>>> @interface.implementer(IGroupAwarePrincipal)
... class DummyGroup(object):
...     def __init__(self, id, title=u'', description=u''):
...         self.id = id
...         self.title = title
...         self.description = description
...         self.groups = []
...
>>> principal = DummyGroup('foo')
>>> zope.security.interfaces.IMemberAwareGroup.providedBy(principal)
False

…when you call the subscriber, it adds the two pseudo-methods to the principal and makes the principal provide the IMemberAwareGroup interface.

>>> zope.pluggableauth.plugins.groupfolder.setMemberSubscriber(
...     interfaces.FoundPrincipalCreated(
...         'dummy auth (ignored)', principal, info))
>>> principal.getMembers()
('joe', 'jane')
>>> principal.setMembers(('joe', 'jane', 'jaimie'))
>>> principal.getMembers()
('joe', 'jane', 'jaimie')
>>> zope.security.interfaces.IMemberAwareGroup.providedBy(principal)
True

The two methods work with the value on the IGroupInformation object.

>>> i.principals == principal.getMembers()
True

Limitation

The current group-folder design has an important limitation!

There is no point in assigning principals to a group from a group folder unless the principal is from the same pluggable authentication utility.

  • If a principal is from a higher authentication utility, the user will not get the group definition. Why? Because the principals group assignments are set when the principal is authenticated. At that point, the current site is the site containing the principal definition. Groups defined in lower sites will not be consulted,
  • It is impossible to assign users from lower authentication utilities because they can’t be seen when managing the group, from the site containing the group.

A better design might be to store user-role assignments independent of the group definitions and to look for assignments during (url) traversal. This could get quite complex though.

While it is possible to have multiple authentication utilities long a URL path, it is generally better to stick to a simpler model in which there is only one authentication utility along a URL path (in addition to the global utility, which is used for bootstrapping purposes).

Changes

2.3.0 (2017-11-12)

  • Drop support for Python 3.3.

2.2.0 (2017-05-02)

  • Add support for Python 3.6.
  • Fix a NameError in the idpicker under Python 3.6. See issue 7.

2.1.0 (2016-07-04)

  • Add support for Python 3.5.
  • Drop support for Python 2.6.

2.0.0 (2014-12-24)

  • Add support for Python 3.4.
  • Refactor zope.pluggableauth.plugins.session.redirectWithComeFrom into a reusable function.
  • Fix: allow password containing colon(s) in HTTP basic authentication credentials extraction plug-in, to conform with RFC2617

2.0.0a1 (2013-02-21)

  • Add tox.ini and MANIFEST.in.
  • Add support for Python 3.3.
  • Replace deprecated zope.component.adapts usage with equivalent zope.component.adapter decorator.
  • Replace deprecated zope.interface.implements usage with equivalent zope.interface.implementer decorator.
  • Drop support for Python 2.4 and 2.5.

1.3 (2011-02-08)

1.2 (2010-12-16)

  • Add a hook to SessionCredentialsPlugin (_makeCredentials) that can be overriden in subclasses to store the credentials in the session differently.

    For example, you could use keas.kmi and encrypt the passwords of the currently logged-in users so they don’t appear in plain text in the ZODB.

1.1 (2010-10-18)

  • Move concrete IAuthenticatorPlugin implementations from zope.app.authentication to zope.pluggableauth.plugins.

    As a result, projects that want to use the IAuthenticator plugins (previously found in zope.app.authentication) do not automatically also pull in the zope.app.* dependencies that are needed to register the ZMI views.

1.0.3 (2010-07-09)

  • Fix dependency declaration.

1.0.2 (2010-07-90)

1.0.1 (2010-02-11)

  • Declare adapter in a new ZCML file : principalfactories.zcml. Avoids duplication errors in zope.app.authentication.

1.0 (2010-02-05)

  • Splitting off from zope.app.authentication
 
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