=====================
 anz.casclient README
=====================

:author:    jiangdongjin
:contact:   eastxing@gmail.com
:date:      2010/09/25
:abstract: This is a Zope PAS plugin that authenticates users against a
           CAS (Central Authentication Service) server.

.. contents::
.. sectnum::

Introduction
============
anz.casclient is a PAS plugin that authenticates users against a CAS
(Central Authentication Service) server.

Overview
========
anz.casclient implement a new PAS plugin 'Anz CAS Client'. It enabling you
to integrate your Zope sites into your CAS SSO solutions.

Credits
========
Thanks to those guys who developed the following products, without your
works anz.casclient will never happen.

- CAS_
- `JA-SIG CAS Client for Java 3.1`_
- CAS4PAS_

.. _CAS: http://www.jasig.org/cas
.. _`JA-SIG CAS Client for Java 3.1`: https://wiki.jasig.org/display/CASC/CAS+Client+for+Java+3.1
.. _CAS4PAS: http://plone.org/products/cas4pas

Comparison with CAS4PAS
=======================
CAS4PAS is the first(if not the only)CAS client used in Zope world, but it
has only implemented partial CAS
`protocol <http://www.jasig.org/cas/protocol>`_, so comes anz.casclient.

anz.casclient have some advantages:

- anz.casclient provides full CAS 1.0/2.0 protocol implementation.
- anz.casclient implemented Single-Sign-Out.
- anz.casclient provides a framework that similar as the official java
  client implementation, this will make it easy to follow the evolution of
  CAS client.

Requirements
============
- Plone 3 or Plone 4
- ZODB3>=3.8.3 (test under 3.8.3 only)
- zope.proxy>=3.4.1 (test under 3.4.1 only)
- zope.bforest

Installation
============
To install anz.casclient into the global Python environment (or a
workingenv), using a traditional Zope 2 instance, you can do this:

* When you're reading this you have probably already run
  ``easy_install anz.casclient``. Find out how to install setuptools
  (and EasyInstall) here:
  http://peak.telecommunity.com/DevCenter/EasyInstall

* Create a file called ``anz.casclient-configure.zcml`` in the
  ``/path/to/instance/etc/package-includes`` directory.  The file
  should only contain this::

    <include package="anz.casclient" />

Alternatively, if you are using zc.buildout and the
plone.recipe.zope2instance recipe to manage your project, you can do this:

* Add ``anz.casclient`` to the list of eggs to install, e.g.:

::

    [buildout]
    ...
    eggs =
        ...
        anz.casclient

* Tell the plone.recipe.zope2instance recipe to install a ZCML slug:

::

    [instance]
    recipe = plone.recipe.zope2instance
    ...
    zcml =
        anz.casclient

* Re-run buildout, e.g. with:

::

    $ ./bin/buildout

You can skip the ZCML slug if you are going to explicitly include the
package from another package's configure.zcml file.

How to use anz.casclient
========================

Create 'Anz CAS Client' plugin
------------------------------
Go into ZMI, {your plone site}\acl_users, add an 'Anz CAS Client' instance,
choose any Id you like, we input 'anz_casclient' for example.

Configure 'Anz CAS Client' plugin
---------------------------------
Go into {your plone site}\acl_users\anz_casclient, in 'Active' tab active
all four interface.

Click 'Authentication' to configure 'Authentication Plugins', move
'anz_casclient' to the top.

Click 'Challenge' to configure 'Challenge Plugins', move 'anz_casclient'
to the top.

Click 'Extraction' to configure 'Extraction Plugins', move 'anz_casclient'
to the top.

Go into 'Properties' tab to configure CAS related properties.

==============================  ===========  ==============================
Property                        Required     Note
serviceUrl                      False        An identify of current service.
                                             CAS will redirects to here
                                             after login. Set this explicitly
                                             but not determine it automatically
                                             from request makes us get more
                                             security assurance. See
                                             `here <https://wiki.jasig.org/display/CASC/CASFilter>`_.
casServerUrlPrefix              True         The start of the CAS server URL.
useSession                      False        Whether to store the Assertion
                                             in session or not. If sessions
                                             are not used, proxy granting
                                             ticket will be required for
                                             each request. Default set to True.
renew                           False        If set to True, CAS will ask
                                             user for credentials again to
                                             authenticate, this may be used
                                             for high-security applications.
                                             Default set to False.
gateway                         False        If set to True, CAS will not
                                             ask the user for credentials.
                                             If the user has a pre-existing
                                             single sign-on session with CAS,
                                             or if a single sign-on session
                                             can be established through
                                             non-interactive means(i.e.
                                             trust authentication), CAS MAY
                                             redirect the client to the URL
                                             specified by the "service"
                                             parameter, appending a valid
                                             service ticket.(CAS also MAY
                                             interpose an advisory page
                                             informing the client that a CAS
                                             authentication has taken place.)
                                             If the client does not have a
                                             single sign-on session with CAS,
                                             and a non-interactive
                                             authentication cannot be
                                             established, CAS MUST redirect
                                             the client to the URL specified
                                             by the "service" parameter with
                                             no "ticket" parameter appended
                                             to the URL. If the "service"
                                             parameter is not specified and
                                             "gateway" is set, the behavior
                                             of CAS is undefined. It is
                                             RECOMMENDED that in this case,
                                             CAS request credentials as if
                                             neither parameter was specified.
                                             This parameter is not compatible
                                             with the "renew" parameter.
                                             Behavior is undefined if both
                                             are set to True. See details
                                             `here_ <http://www.jasig.org/cas/client-integration/gateway>`_.
ticketValidationSpecification   True         Use which CAS protocol to
                                             validate ticket.
                                             one of ['CAS 1.0','CAS 2.0']
proxyCallbackUrlPrefix          False        The start of the proxy callback
                                             url. You should set it point to
                                             current plugin with protocol
                                             'https'. The result url will be
                                             '{proxyCallbackUrlPrefix}/proxyCallback'.
                                             If set, it means this service
                                             will be used as a proxier to
                                             access back-end service on
                                             behalf of a particular user.
acceptAnyProxy                  False        Whether any proxy is OK.
Allowed Proxy Chains            False        Allowed proxy chains. Each
                                             acceptable proxy chain should
                                             include a space-separated list
                                             of URLs. These URLs are
                                             proxier's proxyCallbackUrl.
==============================  ===========  ==============================

Example configures:

- Set 'serviceUrl' to 'http://{my plone site domain}:{port}/plone'
- Set 'casServerUrlPrefix' to 'https://{my cas server domain}:{port}/cas'
- Set 'useSession' to True
- Set 'renew' to False
- Set 'gateway' to False
- Set 'ticketValidationSpecification' to 'CAS 2.0'
- Set 'proxyCallbackUrlPrefix' to 'https://{my plone site domain}:{port}/plone/acl_users/anz_casclient'
- Set 'acceptAnyProxy' to False
- Set 'Allowed Proxy Chains' to None

Configure 'CAS login' entrance
------------------------------
If you use 'Log in' link at the upper-right of the Plone page to login, you
should hide the stock Plone 'Log in' action first. Then add a new one named
'CAS log in' there, set URL(Expression) to
**'string:${globals_view/navigationRootUrl}/caslogin'**

Then add a Script(Python) named '**caslogin**' into 'portal_skins/custom',
its contents looks like:

::

 ## Script (Python) "caslogin"
 ##bind container=container
 ##bind context=context
 ##bind namespace=
 ##bind script=script
 ##bind subpath=traverse_subpath
 ##parameters=
 ##title=CAS Login
 ##
 request = container.REQUEST

 portal = context.portal_url.getPortalObject()
 plugin = portal.acl_users.anz_casclient

 if plugin.casServerUrlPrefix:
     url = plugin.getLoginURL() + '?service=' + plugin.getService()
     if plugin.renew:
         url += '&renew=true'
     if plugin.gateway:
         url += '&gateway=true'

     request.RESPONSE.redirect(  url, lock=1 )

If you use 'login portlet' to login, you should remove the stock Plone
'login portlet' first so as not to confuse users. Then you should write a
new 'CAS login portlet' to authenticate users against CAS or customize
collective.castle_ to work with anz.casclient.

.. _collective.castle: http://plone.org/products/collective.castle/

Configure 'CAS logout' entrance
-------------------------------
If you use 'Log out' link at the upper-right of the Plone page to logout,
you should hide the stock Plone 'Log out' action first. Then add a new one
named 'CAS log out' there, set URL(Expression) to
**'string:${globals_view/navigationRootUrl}/caslogout'**

Then add a Script(Python) named '**caslogout**' into 'portal_skins/custom',
its contents looks like:

::

 ## Script (Python) "caslogout"
 ##bind container=container
 ##bind context=context
 ##bind namespace=
 ##bind script=script
 ##bind subpath=traverse_subpath
 ##parameters=
 ##title=CAS Logout
 ##
 from Products.CMFCore.utils import getToolByName

 request = container.REQUEST
 portal = context.portal_url.getPortalObject()
 cas_client_plugin = portal.acl_users.anz_casclient

 mt = getToolByName( context, 'portal_membership' )
 mt.logoutUser( REQUEST=request )

 request.RESPONSE.redirect( cas_client_plugin.casServerUrlPrefix + '/logout' )

How to use proxy authentication
===============================
Proxy authentication is added by CAS 2.0, for the reason why do we need
it, you can see the details `here. <http://www.jasig.org/cas/proxy-authentication>`_


1. Create two plone sites in one Zope instance, called them **plone** and
   **backend**.
2. Create and configure 'Anz CAS Client' plugin on them(make sure both sites
   can authenticate users against your CAS server).
3. anz.casclient carried a simple example to show how to use it, but it need
   you to do a little customization. Open
   **anz.casclient\anz\casclient\proxyauthexample\view.py** with your
   favorite editor, find **__init__** method and modify it to suit your
   situation:

::

 def __init__( self, context, request ):
     super(ProxyAuthExampleView, self).__init__( context, request )

     # eg. http://xx.xx.xx.xx:8080/backend
     self.BACK_END_SERVICE_URL = 'http://{domain of your zope instance}:{port}/backend'

     # eg. /plone/acl_users/anz_casclient
     self.PATH_TO_PROXIER_PLUGIN = '/plone/acl_users/anz_casclient'

     # eg. /backend/acl_users/anz_casclient
     self.PATH_TO_BACK_END_PLUGIN = '/backend/acl_users/anz_casclient'

4. After that restart your Zope, open a browser and login into site
   **plone** ( suppose user name is **tom** ).
5. Modify location in your browser to
   **http://{domain of your zope instance}:{port}/plone/@@proxyAuthExample/getUserInfoFromTargetService**
   and click Enter, if all things goes well, you'll see:

::

 Hello, tom!


SAML service ticket validation
==============================
From version 1.1, the server is able to connect to a CAS server 3.x and above
and validate the service ticket (ST) against the CAS server using SAML, in order
to retrieve the extra fields for the authenticated user that the CAS server may
be providing. To use his feature, it's required to configure the plugin to use
the SAML validation by configuring the **SAMLValidate** property to ``True``.

In order to do something with the retrieved properties an event
``ISAMLPropertiesExist`` is emmited for a subscriber to be hooked into it.


ToDo
====
* Add automation tests ( I really don't know how to automation test this
  kind of package :) )