CNAME handling in Django middleware example

middleware.py

import threading
from django.conf import settings
from django.http import HttpResponseRedirect

# We used our own model to associate users with sites, but could use django.contrib.sites here.
from .models import Network

# List of allowed URLs if user isn't in the network
ALLOWED = [
    u'/accounts/register/',
    u'/accounts/network_connect/',
]

# There are only a few cases where it's harder or less optimized to pass
# request, so a threading local is used.
_network = threading.local()

def set_network(network):
    _network.network = network

class NetworkMiddleware(object):

    def process_request(self, request):
        network = self.get_network_from_request(request)

        # Make sure network exists
        if not network:
            return HttpResponseRedirect(settings.SITE_ROOT_URL)

        # Make sure user is in this network
        if not request.user.is_anonymous():
            if not network in request.user.network_set.all():
                if request.path in ALLOWED:
                    pass # Allow the request to go through
                else:
                    return HttpResponseRedirect(settings.SITE_ROOT_URL)

        request.network = network

    def get_network_from_request(self, request):
        base_domain = settings.SESSION_COOKIE_DOMAIN

        # Get network from subdomain (http://<network>.domain.com)
        host = request.META.get('HTTP_HOST', '')
        if not host.endswith(base_domain):
            return HttpResponseRedirect(settings.SITE_ROOT_URL)

        vhost = host[:-len(base_domain)].replace('.', '-')

        try:
            network = Network.objects.get(slug=vhost)
        except Network.DoesNotExist:
            network = None

        set_network(network)
        return network