models.py

from urlparse import urljoin
from urllib import urlencode, urlopen
from django.db import models
from django.conf import settings
from django.contrib.auth.models import User
from django.core.exceptions import ObjectDoesNotExist
from cas.exceptions import CasTicketException, CasConfigException
# Ed Crewe - add in signals to delete old tickets
from django.db.models.signals import post_save
from datetime import datetime

class Tgt(models.Model):
    username = models.CharField(max_length = 255, unique = True)
    tgt = models.CharField(max_length = 255)

    def get_proxy_ticket_for(self, service):
        """Verifies CAS 2.0+ XML-based authentication ticket.

        Returns username on success and None on failure.
        """
        if not settings.CAS_PROXY_CALLBACK:
            raise CasConfigException("No proxy callback set in settings")

        try:
            from xml.etree import ElementTree
        except ImportError:
            from elementtree import ElementTree

        params = {'pgt': self.tgt, 'targetService': service}

        url = (urljoin(settings.CAS_SERVER_URL, 'proxy') + '?' +
               urlencode(params))

        page = urlopen(url)

        try:
            response = page.read()
            tree = ElementTree.fromstring(response)
            if tree[0].tag.endswith('proxySuccess'):
                return tree[0][0].text
            else:
                raise CasTicketException("Failed to get proxy ticket")
        finally:
            page.close()

class PgtIOU(models.Model):
    """ Proxy granting ticket and IOU """
    pgtIou = models.CharField(max_length = 255, unique = True)
    tgt = models.CharField(max_length = 255)
    created = models.DateTimeField(auto_now = True)

def get_tgt_for(user):
    if not settings.CAS_PROXY_CALLBACK:
        raise CasConfigException("No proxy callback set in settings")

    try:
        return Tgt.objects.get(username = user.username)
    except ObjectDoesNotExist:
        raise CasTicketException("no ticket found for user " + user.username)

def delete_old_tickets(**kwargs):
    """ Delete tickets if they are over 2 days old 
        kwargs = ['raw', 'signal', 'instance', 'sender', 'created']
    """
    sender = kwargs.get('sender', None)
    now = datetime.now()
    expire = datetime(now.year, now.month, now.day - 2)
    sender.objects.filter(created__lt=expire).delete()

post_save.connect(delete_old_tickets, sender=PgtIOU)
#post_save.connect(delete_old_tickets, sender=Tgt)