source: mauRepo/dj_security/trunk/dj_security/views/dj_security_login.py @ 8740

'''
Created on 29 Oct 2012

@author: mnagni
'''
from django.contrib.auth import authenticate, REDIRECT_FIELD_NAME, \
    SESSION_KEY, BACKEND_SESSION_KEY
from django.shortcuts import render_to_response
from django.core.context_processors import csrf
from django.conf import settings
from django_authopenid.views import not_authenticated, ask_openid,\
    signin_failure, _build_context
from django_authopenid.forms import OpenidSigninForm
from django.db.models import Q
from django.contrib.auth.backends import ModelBackend
from django.shortcuts import render_to_response as render

from userdb_model.models import User

import md5
import logging
import base64
from django_authopenid.utils import get_url_host
from django.core.urlresolvers import reverse
import urllib
from django.http import HttpResponseRedirect
from django.contrib.auth.forms import AuthenticationForm
from django import forms
from django.contrib.auth.signals import user_logged_in
from django.db.utils import DatabaseError
from dj_security.exception import DSJOpenIDNotFoundError

# Get an instance of a logger
LOGGER = logging.getLogger(__name__)

OPENID = 'openid'

def error_handle(request, context):
    form = CEDAAuthenticationForm()
    context['form'] = form
    context.update(csrf(request))
    return render_to_response('login.html', context)

class CedaUserAuthenticationBackend(ModelBackend):
    """
    Extends Django's ``ModelBackend`` to allow login via username, or verification token.

    Args are either ``username`` and ``password``
    and ``token``. In either case, ``is_active`` can also be given.

    For login, is_active is not given, so that the login form can
    raise a specific error for inactive users.
    For password reset, True is given for is_active.
    For signup verficiation, False is given for is_active.
    """

    def __init__(self, *args, **kwargs):
        super(CedaUserAuthenticationBackend, self).__init__(*args, **kwargs)

    def authenticate(self, **kwargs):
        if kwargs:
            username = kwargs.pop("username", None)
            if username:
                username = Q(accountid=username)
                password = kwargs.pop("password", None)
                try:
                    user = User.objects.get(username, **kwargs)
                except User.DoesNotExist:
                    pass
                else:
                    if user.md5passwd == md5.new(password).hexdigest():
                        return user
      
'''
def login(request):       
    context = {}
    if request.method == 'POST': # If the form has been submitted...
        form = CEDAAuthenticationForm(request.POST) # A form bound to the POST data
        context['form'] = form
        if form.is_valid(): # All validation rules pass
            username = request.POST.get('username')
            password = request.POST.get('password')
            LOGGER.debug("logging: %s" % (username))            
            user = authenticate(username=username, password=password)             
            if user is not None:
                LOGGER.debug("authenticated: %s" % (username))
                if user.is_active:
                    LOGGER.debug("user %s is Active" % (username))           
                    context['user'] = SecurityEncoder().encode(user)
                    request.auth_user = context.get('user')
                    return _encode_authenticated_response(request, context)         
                else:
                    # Return a 'disabled account' error message
                    context['error'] = u'account disabled'
                    LOGGER.debug("Account Disabled for user %s" % (username))                    
                    return error_handle(request, context)
            else:
                # Return an 'invalid login' error message.
                context['error'] = u'invalid login'                
                LOGGER.debug("Invalid login for user %s" % (username))                
                return error_handle(request, context)
        else:
            context['error'] = u'form is invalid'
            return error_handle(request, context)
    else:
        if getattr(settings, "FAKE_AUTHENTICATION", False):
            context['user'] = '{"username": "mnagni", '
            '"first_name": "Maurizio", "last_name": "Nagni", '
            '"is_active": true, "email": "maurizio.nagni@stfc.ac.uk", '
            '"is_superuser": false, "is_staff": true, '
            '"last_login": "2012-10-18 11:05:28.700139+00:00", '
            '"date_joined": "2012-03-22 14:20:56+00:00", "id": 29, '
            '"permissions": "auth.add_user,proginfo.add_dataproduct, '
            'proginfo.change_programme, cedainfoapp.delete_vmrequest"}'
            return _encode_authenticated_response(request, context)  
        
        # An unbound form
        form = CEDAAuthenticationForm() 
        context['form'] = form
        context.update(csrf(request))
        return render_to_response('login.html', context)
'''
   
def get_user_byopenid(user_id):
    """
        Returns a tbusers row specified by `user_id`
    - String **user_id**
        a user
    """
    try:
        return User.objects.get(openid=user_id)
    except DatabaseError as ex:
        logging.error("Openid: %s - Not Found" % user_id)
        raise DSJOpenIDNotFoundError(ex)   
                    
def logged_in(request):
    '''
        Retrieves the user after the openid provider authenticated him/her
    '''
    if SESSION_KEY not in request.session:
        if OPENID in request.session:
            login(request, get_user_byopenid(request.session[OPENID]))
            
    return _encode_authenticated_response(request, context = {})    
    
def _encode_authenticated_response(request, context):
    redirect_parameter = getattr(settings, 'REDIRECT_URL', 'r')
    context['redirect_url'] = \
        base64.b64decode(request.session.get(redirect_parameter, ''))
    LOGGER.debug("Redirecting to %s" % (context['redirect_url']))   
    return render_to_response('logged_in.html', context)

class CEDAAuthenticationForm(AuthenticationForm):

    def __init__(self, request=None, *args, **kwargs):
        super(CEDAAuthenticationForm, self).__init__(request, *args, **kwargs)

    def clean(self):
        username = self.cleaned_data.get('username')
        password = self.cleaned_data.get('password')

        if username and password:
            self.user_cache = authenticate(username=username,
                                           password=password)
            if self.user_cache is None:
                raise forms.ValidationError(
                    self.error_messages['invalid_login'])
            #elif not self.user_cache.is_active:
            #    raise forms.ValidationError(self.error_messages['inactive'])
        self.check_for_test_cookie()
        return self.cleaned_data

    
@not_authenticated
def signin(request, template_name='authopenid/signin.html', 
        redirect_field_name=REDIRECT_FIELD_NAME, openid_form=OpenidSigninForm,
        auth_form=CedaUserAuthenticationBackend, on_failure=None, extra_context=None):
    """Signin page. It manage the legacy authentification (user/password)  
    and authentification with openid.

    :attr request: request object
    :attr template_name: string, name of template to use
    :attr redirect_field_name: string, field name used for redirect. by 
    default 'next'
    :attr openid_form: form use for openid signin, by default 
    `OpenidSigninForm`
    :attr auth_form: form object used for legacy authentification. 
    By default AuthentificationForm form auser auth contrib.
    :attr extra_context: A dictionary of variables to add to the 
    template context. Any callable object in this dictionary will 
    be called to produce the end result which appears in the context.
    """
    if on_failure is None:
        on_failure = signin_failure
        
    redirect_to = request.REQUEST.get(redirect_field_name, '')
    form1 = openid_form()
    form2 = auth_form()
    if request.POST:
        if not redirect_to or '//' in redirect_to or ' ' in redirect_to:
            redirect_to = settings.LOGIN_REDIRECT_URL     
        if 'openid_url' in request.POST.keys():
            form1 = openid_form(data=request.POST)
            if form1.is_valid():
                redirect_url = "%s%s?%s" % (
                        get_url_host(request),
                        reverse('user_complete_signin'), 
                        urllib.urlencode({ redirect_field_name: redirect_to })
                )
                return ask_openid(request, 
                        form1.cleaned_data['openid_url'], 
                        redirect_url, 
                        on_failure=on_failure)
        else:
            # perform normal django authentification
            form2 = auth_form(data=request.POST)
            if form2.is_valid():
                login(request, form2.get_user())
                if request.session.test_cookie_worked():
                    request.session.delete_test_cookie()
                return HttpResponseRedirect(redirect_to)
    return render(template_name, {
        'form1': form1,
        'form2': form2,
        redirect_field_name: redirect_to,
        'msg':  request.GET.get('msg','')
    }, context_instance=_build_context(request, extra_context=extra_context))  


    
def login(request, user):
    """
    Persist a user id and a backend in the request. This way a user doesn't
    have to reauthenticate on every request. Note that data set during
    the anonymous session is retained when the user logs in.
    Overrides the django.contrib.auth.login method
    """
    if user is None:
        user = request.user
    # TODO: It would be nice to support different login methods, like signed cookies.
    if SESSION_KEY in request.session:
        if request.session[SESSION_KEY] != user.accountid:
            # To avoid reusing another user's session, create a new, empty
            # session if the existing session corresponds to a different
            # authenticated user.
            r_copy = None
            if request.session.has_key('r'):
                r_copy = request.session['r']
            request.session.flush()
            request.user = user
            request.session['r'] = r_copy
    else:
        request.session.cycle_key()
    request.session[SESSION_KEY] = user.userkey
    request.session[BACKEND_SESSION_KEY] = user.backend
    if hasattr(request, 'user'):
        request.user = user
    user_logged_in.send(sender=user.__class__, request=request, user=user)