111 lines
3.7 KiB
Python
111 lines
3.7 KiB
Python
import logging
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from django.contrib.sessions.backends.base import CreateError, SessionBase, UpdateError
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from django.core.exceptions import SuspiciousOperation
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from django.db import DatabaseError, IntegrityError, router, transaction
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from django.utils import timezone
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from django.utils.functional import cached_property
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class SessionStore(SessionBase):
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"""
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Implement database session store.
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"""
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def __init__(self, session_key=None):
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super().__init__(session_key)
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@classmethod
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def get_model_class(cls):
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# Avoids a circular import and allows importing SessionStore when
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# django.contrib.sessions is not in INSTALLED_APPS.
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from django.contrib.sessions.models import Session
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return Session
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@cached_property
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def model(self):
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return self.get_model_class()
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def _get_session_from_db(self):
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try:
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return self.model.objects.get(
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session_key=self.session_key, expire_date__gt=timezone.now()
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)
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except (self.model.DoesNotExist, SuspiciousOperation) as e:
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if isinstance(e, SuspiciousOperation):
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logger = logging.getLogger("django.security.%s" % e.__class__.__name__)
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logger.warning(str(e))
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self._session_key = None
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def load(self):
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s = self._get_session_from_db()
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return self.decode(s.session_data) if s else {}
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def exists(self, session_key):
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return self.model.objects.filter(session_key=session_key).exists()
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def create(self):
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while True:
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self._session_key = self._get_new_session_key()
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try:
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# Save immediately to ensure we have a unique entry in the
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# database.
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self.save(must_create=True)
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except CreateError:
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# Key wasn't unique. Try again.
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continue
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self.modified = True
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return
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def create_model_instance(self, data):
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"""
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Return a new instance of the session model object, which represents the
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current session state. Intended to be used for saving the session data
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to the database.
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"""
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return self.model(
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session_key=self._get_or_create_session_key(),
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session_data=self.encode(data),
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expire_date=self.get_expiry_date(),
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)
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def save(self, must_create=False):
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"""
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Save the current session data to the database. If 'must_create' is
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True, raise a database error if the saving operation doesn't create a
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new entry (as opposed to possibly updating an existing entry).
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"""
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if self.session_key is None:
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return self.create()
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data = self._get_session(no_load=must_create)
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obj = self.create_model_instance(data)
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using = router.db_for_write(self.model, instance=obj)
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try:
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with transaction.atomic(using=using):
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obj.save(
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force_insert=must_create, force_update=not must_create, using=using
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)
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except IntegrityError:
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if must_create:
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raise CreateError
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raise
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except DatabaseError:
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if not must_create:
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raise UpdateError
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raise
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def delete(self, session_key=None):
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if session_key is None:
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if self.session_key is None:
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return
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session_key = self.session_key
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try:
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self.model.objects.get(session_key=session_key).delete()
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except self.model.DoesNotExist:
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pass
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@classmethod
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def clear_expired(cls):
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cls.get_model_class().objects.filter(expire_date__lt=timezone.now()).delete()
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