dolmen.app.authentication 1.0a1

Dolmen CMS authentication package

dolmen.app.authentication is the package responsible for the users and groups management in a Dolmen application. Built on the on the top of dolmen.authentication and zope.pluggableauth, it provides a set of plugins and base classes that can help building a complex users & groups system.

Initial Grok imports

>>> import grok
>>> from grokcore.component.testing import grok_component

Credentials plugins

>>> from zope.pluggableauth.interfaces import ICredentialsPlugin

Credentials plugins are responsible for the extraction of credentials, in order to identify a user. dolmen.app.authentication provides a single plugin, out of the box - Cookies Credentials.

Cookies Credentials

The cookie credentials plugin extracts the credentials from cookies. This plugin is based on Philipp von Weitershausen’s work (wc.cookiecredentials). It has been reimplemented to avoid the use of the zope.app packages and allow more flexibility in the long run.

This plugin provides the following capabilities:

• challenge the user to enter username and password through a login form;

• save those credentials to a cookie from which it can read them back at any later time.

To check if the credentials can correctly be exacted, we can forge the cookie ourselves in a test request:

>>> import base64
>>> from zope.publisher.browser import TestRequest

>>> cookie = base64.encodestring('mgr:mgrpw')
>>> request = TestRequest()
>>> request._cookies = {'dolmen.authcookie': cookie}

Calling the plugin credentials extractor will give us exactly what we need to proceed to the authentication:

>>> from zope.interface.verify import verifyObject
>>> from dolmen.app.authentication.plugins import CookiesCredentials

>>> plugin = CookiesCredentials()
>>> verifyObject(ICredentialsPlugin, plugin)
True

>>> print plugin.extractCredentials(request)
{'login': 'mgr', 'password': 'mgrpw'}

Authenticator Plugins

>>> from zope.pluggableauth.interfaces import IAuthenticatorPlugin

Authenticator plugins uses extracted credentials in order to retrieve and identify principals. dolmen.app.authentication provides two plugins - Global Registry Authentication & Principal Folder Authentication

Global Registry Authentication

In order to register principals, the zope.principalregistry package provides a global registry that is not persistent and re-constructed at each startup. The Global Registry Authenticator is meant to look up the principal inside that global registry.

We verify the integrity of our implementation against the requirements:

>>> from dolmen.app.authentication import plugins
>>> IAuthenticatorPlugin.implementedBy(plugins.GlobalRegistryAuth)
True

>>> plugin = plugins.GlobalRegistryAuth()
>>> verifyObject(IAuthenticatorPlugin, plugin)
True

In order to test this plugin, we registered a user, called “mgr” in the global registry. We’ll test the look up using “mgr” credentials:

>>> user = plugin.authenticateCredentials(
...            {'login': "mgr", "password": "mgrpw"})
>>> print user
PrincipalInfo(u'zope.mgr')

Wrong credentials will make the authentication return None:

>>> user = plugin.authenticateCredentials(
...            {'login': "mgr", "password": "wrongpass"})
>>> user is None
True

>>> user = plugin.authenticateCredentials(
...            {'login': "anon", "password": "wrongpass"})
>>> user is None
True

It is possible to get the principal info alone, as required by the IAuthenticatorPlugin interface:

>>> print plugin.principalInfo('zope.mgr')
PrincipalInfo(u'zope.mgr')

>>> print plugin.principalInfo('zorglub')
Traceback (most recent call last):
...
PrincipalLookupError: zorglub

Note that the principal info is retrieved using its id and not its login. The id is unique and prefixed by the registry’s own prefix, to make it easily identifiable and retrievable.

Principal Folder Authentication

dolmen.app.authentication introduces another authenticator plugin meant to store and retrieve persistent principals. This plugin is a container that can store IPrincipal objects and retrieve them following the IAuthenticatorPlugin’s prescriptions.

We verify the integrity of our implementation against the requirements:

>>> from dolmen.app.authentication import plugins
>>> IAuthenticatorPlugin.implementedBy(plugins.PrincipalFolderPlugin)
True

>>> plugin = plugins.PrincipalFolderPlugin()
>>> verifyObject(IAuthenticatorPlugin, plugin)
True

In order to test this plugin, we have to create an IPrincipal object and store it inside the plugin. Then, we can test the look up.

In order to make the authentication pluggable, the principal authenticator plugin relies on 3 interfaces:

• IAccountStatus : if an adaptation exist to this interface from the IPrincipal object, it is used to figure out if the principal can login or not. It allows disabling a user account and computing that disability.

• IPasswordChecker: this adapter is used to check the credentials. If it doesnt exist (or if the IPrincipal object doesn’t provide this interface), the authentication is aborted and None is returned.

• IPrincipalInfo: unlike the previous plugin, the Principal Folder authenticator doesn’t directly return a PrincipalInfo object, but uses an adapter to retrieve the appropriate principal info object. This is required in order to plug specific behavior into our authentication system.

Let’s first implement a basic IPrincipalObject. Once stored, we’ll be able to start the look ups and the adapters implementations:

>>> from dolmen.app.authentication.tests import User

See the implementation below:

from dolmen.authentication import IPrincipal
from zope.interface import implements

class User(object):
    implements(IPrincipal)

    def __init__(self, id, title=u"", desc=u""):
        self.id = id
        self.title = title or id
        self.description = desc
        self.groups = []

We can verify our implementation against the interface:

>>> from dolmen.authentication import IPrincipal
>>> stilgar = User(u"stilgar")
>>> verifyObject(IPrincipal, stilgar)
True

The implementation is consistent. We can now persist the principal in the plugin container:

>>> plugin['stilgar'] = stilgar
>>> print [user for user in plugin.keys()]
[u'stilgar']

We can now try to look up the principal, using the authentication API:

>>> found = plugin.authenticateCredentials(
...            {'login': 'stilgar', 'password': 'boo'})
>>> found is None
True

The principal is not found : we do not have an adapter to IPasswordChecker available, therefore the authentication process has been aborted.

Providing the adapter will allow us to successfully retrieve the principal:

>>> from dolmen.authentication import IPasswordChecker

>>> class GrantingAccessOnBoo(grok.Adapter):
...     grok.context(IPrincipal)
...     grok.provides(IPasswordChecker)
...
...     def checkPassword(self, pwd):
...         if pwd == 'boo':
...             return True

>>> grok_component('booing', GrantingAccessOnBoo)
True

>>> found = plugin.authenticateCredentials(
...            {'login': 'stilgar', 'password': 'boo'})
>>> found is not None
True

Of course, providing a wrong password will return None:

>>> found = plugin.authenticateCredentials(
...            {'login': 'stilgar', 'password': 'not boo'})
>>> found is None
True

As seen previously, it is possible to switch on and off the ability to log in, for a given user, thanks to the IAccountStatus interface:

>>> from dolmen.authentication import IAccountStatus

>>> class AllowLogin(grok.Adapter):
...     grok.context(IPrincipal)
...     grok.provides(IAccountStatus)
...
...     @property
...     def status(self):
...         return "No status information available"
...
...     def check(self):
...         if self.context.id != "stilgar":
...             return True
...         return False

>>> grok_component('allow', AllowLogin)
True

In this example, we explictly disallow the user with the identifier “stilgar” to be retrieved by the login:

>>> found = plugin.authenticateCredentials(
...            {'login': 'stilgar', 'password': 'boo'})
>>> found is None
True

Setting up a site

In order to test the advanced features of the package, we’ll set up a familiar environment. Doing so, we can test the behavior of our package in the context of a real Dolmen site:

>>> from dolmen.app.site import Dolmen
>>> root = getRootFolder()

>>> site = Dolmen()
>>> grok.notify(grok.ObjectCreatedEvent(site))
>>> root['site'] =  site

>>> from zope.authentication.interfaces import IAuthentication
>>> from zope.pluggableauth import PluggableAuthentication
>>> from dolmen.app.authentication import initialize_pau

>>> PAU = PluggableAuthentication()
>>> len(PAU.authenticatorPlugins)
0
>>> len(PAU.credentialsPlugins)
0

>>> initialize_pau(PAU)
>>> print PAU.authenticatorPlugins
('globalregistry',)
>>> print PAU.credentialsPlugins
('cookies', 'No Challenge if Authenticated')

>>> site['auth'] = PAU
>>> lsm = site.getSiteManager()
>>> lsm.registerUtility(PAU, IAuthentication)

Logging in

UnAuthorized

Imagine you go to a page that anonymous users don’t have access to:

>>> from zope.app.wsgi.testlayer import Browser
>>> browser = Browser()

>>> browser.open("http://localhost/site/@@edit")
>>> unauthorized = browser.contents
>>> 'id="login" name="login"' in unauthorized
True
>>> 'id="password" name="password"' in unauthorized
True

The login page

To get the right credentials, we can simply log in, using the login form provided by dolmen.app.authentication:

>>> browser.open('http://localhost/site/@@login')
>>> loginpage = browser.contents
>>> 'id="login" name="login"' in loginpage
True
>>> 'id="password" name="password"' in loginpage
True

>>> browser.getControl('Username').value = 'mgr'
>>> browser.getControl('Password').value = 'mgrpw'
>>> browser.getControl('Log in').click()

>>> browser.url
'http://localhost/site'

>>> browser.open("http://localhost/site/@@edit")
>>> "<h1>Edit: My Dolmen Site</h1>\n" in browser.contents
True

Managing the authentication plugins

dolmen.app.authentication provides a way to enable and disable the different authentication plugins.

In order to keep the elements tidied up, in the site, dolmen.app.authentication assumes that the authenticator plugins are persisted inside the PAU container.

Let’s have a concrete exemple with a PrincipalFolder plugin:

>>> members = plugins.PrincipalFolderPlugin()
>>> grok.notify(grok.ObjectCreatedEvent(members))
>>> PAU['members'] = members

At this point, the PrincipalFolder is created and persisted. As we notice, the folder is created inside the PAU utility container.

At this point, we can access the management view:

>>> browser.open("http://localhost/site/auth/@@authenticators")
>>> print browser.contents
<!DOCTYPE html PUBLIC...
<div class="fields">
  <div class="field">
    <label class="field-label"
           for="form-field-activeFolders">Active authentication sources</label>
    ...
    <input type="checkbox" id="form-field-activeFolders-members" name="form.field.activeFolders" value="members" class="field-tuple" />
    <label for="form-field-activeFolders-members">members (members)</label>
    <br />
    ...

The “members” principal folder is not yet activated.

Let’s create a User object inside it:

>>> chani = User(u"chani", title=u"Sihaya")
>>> PAU['members']['chani'] = chani

Now, with a new browser, let’s try to login:

>>> new_browser = Browser()
>>> new_browser.open('http://localhost/site/@@login')
>>> new_browser.getControl('Username').value = 'chani'
>>> new_browser.getControl('Password').value = 'boo'
>>> new_browser.getControl('Log in').click()

>>> "Login failed" in new_browser.contents
True

Using the management view mechanisms, we can activate our principal folder:

>>> from dolmen.app.authentication.browser import management
>>> adapter = management.IActiveFolders(PAU)
>>> adapter.activeFolders
()
>>> adapter.activeFolders = (u'members',)

The principal folder is now activated. Let’s retry to log in:

>>> new_browser = Browser()
>>> new_browser.handleErrors = False

>>> new_browser.open('http://localhost/site/@@login')
>>> new_browser.getControl('Username').value = 'chani'
>>> new_browser.getControl('Password').value = 'boo'
>>> new_browser.getControl('Log in').click()

>>> "Login failed" in new_browser.contents
False

>>> print new_browser.url
http://localhost/site

Managing the users

Users can be granted roles. This can be done through a view, with the user as the context:

>>> browser.open("http://localhost/site/auth/members/chani/@@grant_roles")
>>> print browser.contents
<!DOCTYPE html PUBLIC...
...<h1>Edit: Sihaya</h1>...
<div class="fields">
  <div class="field">
    <label class="field-label" for="form-field-roles">roles</label>
...
    <input type="checkbox" id="form-field-roles-dolmen-Contributor" name="form.field.roles" value="dolmen.Contributor" class="field-list" />
      <label for="form-field-roles-dolmen-Contributor">dolmen.Contributor</label>
      <br />
     <input type="checkbox" id="form-field-roles-dolmen-Member" name="form.field.roles" value="dolmen.Member" class="field-list" />
      <label for="form-field-roles-dolmen-Member">dolmen.Member</label>
      <br />
     <input type="checkbox" id="form-field-roles-dolmen-Owner" name="form.field.roles" value="dolmen.Owner" class="field-list" />
      <label for="form-field-roles-dolmen-Owner">dolmen.Owner</label>
      <br />
     <input type="checkbox" id="form-field-roles-dolmen-Reviewer" name="form.field.roles" value="dolmen.Reviewer" class="field-list" />
      <label for="form-field-roles-dolmen-Reviewer">dolmen.Reviewer</label>
      <br />
...

This view is possible thanks to an adapter, useable on any IPrincipals:

>>> from zope.component.hooks import setSite
>>> setSite(site) # we got to the context of our site

>>> from dolmen.app.authentication.browser import roles
>>> role_controller = roles.IPrincipalRoles(chani)
>>> role_controller.roles
[]

>>> role_controller.roles = ['dolmen.Member']
>>> role_controller.roles
['dolmen.Member']

The role management applies the changes on the site object itself. Let’s verify if the role has been correctly applied:

>>> from zope.securitypolicy.interfaces import IPrincipalRoleManager
>>> prm = IPrincipalRoleManager(site)
>>> print prm.getRolesForPrincipal(chani.id)
[('dolmen.Member', PermissionSetting: Allow)]

Logging out

We can also manually destroy the cookie by invoking the logout page:

>>> 'dolmen.authcookie' in browser.cookies.keys()
True

>>> browser.open("http://localhost/site/@@logoutaction")
>>> 'dolmen.authcookie' in browser.cookies.keys()
False

>>> browser.url
'http://localhost/site/logout.html'

Changes

1.0a1 (2010-06-04)

• Removed unused and illogical rights: “CanLogin” & “CanLogout”.

• dolmen.app.authentication now uses dolmen.menu to create menus and register entries.

• We now use the zeam.form Form library instead of z3c.form

0.1.1 (2010-05-31)

• Updated translations.

0.1 (2010-05-30)

• Initial release.