etesync-server/myauth/ldap.py

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import logging
from django.utils import timezone
from django.conf import settings
from django.core.exceptions import PermissionDenied
from rest_framework.permissions import BasePermission
import ldap
def ldap_setting(name, default):
'''Wrapper around django.conf.settings'''
return getattr(settings, f'LDAP_{name}', default)
class LDAPConnection:
__instance__ = None
__user_cache = {} # Username -> Valid until
@staticmethod
def get_instance():
'''To get a Singleton'''
if not LDAPConnection.__instance__:
return LDAPConnection()
else:
return LDAPConnection.__instance__
def __init__(self):
# Cache some settings
self.__LDAP_FILTER = ldap_setting('FILTER', '')
self.__LDAP_SEARCH_BASE = ldap_setting('SEARCH_BASE', '')
self.__ldap_connection = ldap.initialize(ldap_setting('SERVER', ''))
try:
self.__ldap_connection.simple_bind_s(ldap_setting('BIND_DN', ''),
ldap_setting('BIND_PW', ''))
except ldap.LDAPError as err:
logging.error(f'LDAP Error occuring during bind: {err.desc}')
def __is_cache_valid(self, username):
'''Returns True if the cache entry is still valid. Returns False otherwise.'''
if username in self.__user_cache:
if timezone.now() <= self.__user_cache[username]:
# Cache entry is still valid
return True
return False
def __remove_cache(self, username):
del self.__user_cache[username]
def has_user(self, username):
'''
Since we don't care about the password and so authentication
another way, all we care about is whether the user exists.
'''
if self.__is_cache_valid(username):
return True
if username in self.__user_cache:
self.__remove_cache(username)
filterstr = self.__LDAP_FILTER.replace('%s', username)
try:
result = self.__ldap_connection.search_s(self.__LDAP_SEARCH_BASE,
ldap.SCOPE_SUBTREE,
filterstr=filterstr)
except ldap.NO_RESULTS_RETURNED:
# We handle the specific error first and the the generic error, as
# we may expect ldap.NO_RESULTS_RETURNED, but not any other error
return False
except ldap.LDAPError as err:
logging.error(f'Error occured while performing an LDAP query: {err.desc}')
return False
if len(result) == 1:
self.__user_cache[username] = timezone.now() + timezone.timedelta(hours=1)
return True
return False
class LDAPUserExists(BasePermission):
'''
A permission check which first checks with the LDAP directory if the user
exists.
'''
def has_permission(self, request, view):
return LDAPConnection.get_instance().has_user(request.user.username):
def create_user(*args, **kwargs):
'''
A create_user function which first checks if the user already exists in the
configured LDAP directory.
'''
if not LDAPConnection.get_instance().has_user(kwargs['username']):
raise PermissionDenied('User not in the LDAP directory.')
return User.objects.create_user(*args, **kwargs)