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