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"""
SessionSecurityMiddleware is the heart of the security that this application
attemps to provide.
To install this middleware, add to your ``settings.MIDDLEWARE_CLASSES``::
'session_security.middleware.SessionSecurityMiddleware'
Make sure that it is placed **after** authentication middlewares.
"""
from datetime import datetime, timedelta
from django.contrib.auth import logout
from django.core.urlresolvers import reverse
from .utils import get_last_activity, set_last_activity
from .settings import EXPIRE_AFTER, PASSIVE_URLS
class SessionSecurityMiddleware(object):
"""
In charge of maintaining the real 'last activity' time, and log out the
user if appropriate.
"""
def is_passive_request(self, request):
return request.path in PASSIVE_URLS
def get_expire_seconds(self, request):
"""Return time (in seconds) before the user should be logged out."""
return EXPIRE_AFTER
def process_request(self, request):
""" Update last activity time or logout. """
if not request.user.is_authenticated():
return
now = datetime.now()
if '_session_security' not in request.session:
set_last_activity(request.session, now)
return
delta = now - get_last_activity(request.session)
expire_seconds = self.get_expire_seconds(request)
if delta >= timedelta(seconds=expire_seconds):
logout(request)
elif (request.path == reverse('session_security_ping') and
'idleFor' in request.GET):
self.update_last_activity(request, now)
elif not self.is_passive_request(request):
set_last_activity(request.session, now)
def update_last_activity(self, request, now):
"""
If ``request.GET['idleFor']`` is set, check if it refers to a more
recent activity than ``request.session['_session_security']`` and
update it in this case.
"""
last_activity = get_last_activity(request.session)
server_idle_for = (now - last_activity).seconds
# Gracefully ignore non-integer values
try:
client_idle_for = int(request.GET['idleFor'])
except ValueError:
return
# Disallow negative values, causes problems with delta calculation
if client_idle_for < 0:
client_idle_for = 0
if client_idle_for < server_idle_for:
# Client has more recent activity than we have in the session
last_activity = now - timedelta(seconds=client_idle_for)
# Update the session
set_last_activity(request.session, last_activity)
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