import binascii
import os
import pickle
import time
from webob.cookies import JSONSerializer, SignedSerializer
from zope.deprecation import deprecated
from zope.interface import implementer
from pyramid.csrf import check_csrf_origin, check_csrf_token
from pyramid.interfaces import ISession
from pyramid.util import bytes_, text_
def manage_accessed(wrapped):
"""Decorator which causes a cookie to be renewed when an accessor
method is called."""
def accessed(session, *arg, **kw):
session.accessed = now = int(time.time())
if session._reissue_time is not None:
if now - session.renewed > session._reissue_time:
session.changed()
return wrapped(session, *arg, **kw)
accessed.__doc__ = wrapped.__doc__
return accessed
def manage_changed(wrapped):
"""Decorator which causes a cookie to be set when a setter method
is called."""
def changed(session, *arg, **kw):
session.accessed = int(time.time())
session.changed()
return wrapped(session, *arg, **kw)
changed.__doc__ = wrapped.__doc__
return changed
[docs]
class PickleSerializer:
"""
.. deprecated:: 2.0
.. warning::
In :app:`Pyramid` 2.0 the default ``serializer`` option changed to
use :class:`pyramid.session.JSONSerializer`, and ``PickleSerializer``
has been been removed from active Pyramid code.
Pyramid will require JSON-serializable objects in :app:`Pyramid` 2.0.
Please see :ref:`upgrading_session_20`.
A serializer that uses the pickle protocol to dump Python data to bytes.
This was the default serializer used by Pyramid, but has been deprecated.
``protocol`` may be specified to control the version of pickle used.
Defaults to :attr:`pickle.HIGHEST_PROTOCOL`.
"""
def __init__(self, protocol=pickle.HIGHEST_PROTOCOL):
self.protocol = protocol
def loads(self, bstruct):
"""Accept bytes and return a Python object."""
try:
return pickle.loads(bstruct)
except Exception:
# this block should catch at least:
# ValueError, AttributeError, ImportError; but more to be safe
raise ValueError
def dumps(self, appstruct):
"""Accept a Python object and return bytes."""
return pickle.dumps(appstruct, self.protocol)
deprecated(
'PickleSerializer',
'pyramid.session.PickleSerializer is deprecated as of Pyramid 2.0 for '
'security concerns. Use pyramid.session.JSONSerializer or reference the '
'narrative documentation for information on building a migration tool.',
)
JSONSerializer = JSONSerializer # api
[docs]
def BaseCookieSessionFactory(
serializer,
cookie_name='session',
max_age=None,
path='/',
domain=None,
secure=False,
httponly=False,
samesite='Lax',
timeout=1200,
reissue_time=0,
set_on_exception=True,
):
"""
Configure a :term:`session factory` which will provide cookie-based
sessions. The return value of this function is a :term:`session factory`,
which may be provided as the ``session_factory`` argument of a
:class:`pyramid.config.Configurator` constructor, or used as the
``session_factory`` argument of the
:meth:`pyramid.config.Configurator.set_session_factory` method.
The session factory returned by this function will create sessions
which are limited to storing fewer than 4000 bytes of data (as the
payload must fit into a single cookie).
.. warning:
This class provides no protection from tampering and is only intended
to be used by framework authors to create their own cookie-based
session factories.
Parameters:
``serializer``
An object with two methods: ``loads`` and ``dumps``. The ``loads``
method should accept bytes and return a Python object. The ``dumps``
method should accept a Python object and return bytes. A ``ValueError``
should be raised for malformed inputs.
``cookie_name``
The name of the cookie used for sessioning. Default: ``'session'``.
``max_age``
The maximum age of the cookie used for sessioning (in seconds).
Default: ``None`` (browser scope).
``path``
The path used for the session cookie. Default: ``'/'``.
``domain``
The domain used for the session cookie. Default: ``None`` (no domain).
``secure``
The 'secure' flag of the session cookie. Default: ``False``.
``httponly``
Hide the cookie from Javascript by setting the 'HttpOnly' flag of the
session cookie. Default: ``False``.
``samesite``
The 'samesite' option of the session cookie. Set the value to ``None``
to turn off the samesite option. Default: ``'Lax'``.
``timeout``
A number of seconds of inactivity before a session times out. If
``None`` then the cookie never expires. This lifetime only applies
to the *value* within the cookie. Meaning that if the cookie expires
due to a lower ``max_age``, then this setting has no effect.
Default: ``1200``.
``reissue_time``
The number of seconds that must pass before the cookie is automatically
reissued as the result of a request which accesses the session. The
duration is measured as the number of seconds since the last session
cookie was issued and 'now'. If this value is ``0``, a new cookie
will be reissued on every request accessing the session. If ``None``
then the cookie's lifetime will never be extended.
A good rule of thumb: if you want auto-expired cookies based on
inactivity: set the ``timeout`` value to 1200 (20 mins) and set the
``reissue_time`` value to perhaps a tenth of the ``timeout`` value
(120 or 2 mins). It's nonsensical to set the ``timeout`` value lower
than the ``reissue_time`` value, as the ticket will never be reissued.
However, such a configuration is not explicitly prevented.
Default: ``0``.
``set_on_exception``
If ``True``, set a session cookie even if an exception occurs
while rendering a view. Default: ``True``.
.. versionadded: 1.5a3
.. versionchanged: 1.10
Added the ``samesite`` option and made the default ``'Lax'``.
"""
@implementer(ISession)
class CookieSession(dict):
"""Dictionary-like session object"""
# configuration parameters
_cookie_name = cookie_name
_cookie_max_age = max_age if max_age is None else int(max_age)
_cookie_path = path
_cookie_domain = domain
_cookie_secure = secure
_cookie_httponly = httponly
_cookie_samesite = samesite
_cookie_on_exception = set_on_exception
_timeout = timeout if timeout is None else int(timeout)
_reissue_time = (
reissue_time if reissue_time is None else int(reissue_time)
)
# dirty flag
_dirty = False
def __init__(self, request):
self.request = request
now = time.time()
created = renewed = now
new = True
value = None
state = {}
cookieval = request.cookies.get(self._cookie_name)
if cookieval is not None:
try:
value = serializer.loads(bytes_(cookieval))
except ValueError:
# the cookie failed to deserialize, dropped
value = None
if value is not None:
try:
# since the value is not necessarily signed, we have
# to unpack it a little carefully
rval, cval, sval = value
renewed = float(rval)
created = float(cval)
state = sval
new = False
except (TypeError, ValueError):
# value failed to unpack properly or renewed was not
# a numeric type so we'll fail deserialization here
state = {}
if self._timeout is not None:
if now - renewed > self._timeout:
# expire the session because it was not renewed
# before the timeout threshold
state = {}
self.created = created
self.accessed = renewed
self.renewed = renewed
self.new = new
dict.__init__(self, state)
# ISession methods
def changed(self):
if not self._dirty:
self._dirty = True
def set_cookie_callback(request, response):
self._set_cookie(response)
self.request = None # explicitly break cycle for gc
self.request.add_response_callback(set_cookie_callback)
def invalidate(self):
self.clear() # XXX probably needs to unset cookie
# non-modifying dictionary methods
get = manage_accessed(dict.get)
__getitem__ = manage_accessed(dict.__getitem__)
items = manage_accessed(dict.items)
values = manage_accessed(dict.values)
keys = manage_accessed(dict.keys)
__contains__ = manage_accessed(dict.__contains__)
__len__ = manage_accessed(dict.__len__)
__iter__ = manage_accessed(dict.__iter__)
# modifying dictionary methods
clear = manage_changed(dict.clear)
update = manage_changed(dict.update)
setdefault = manage_changed(dict.setdefault)
pop = manage_changed(dict.pop)
popitem = manage_changed(dict.popitem)
__setitem__ = manage_changed(dict.__setitem__)
__delitem__ = manage_changed(dict.__delitem__)
# flash API methods
@manage_changed
def flash(self, msg, queue='', allow_duplicate=True):
storage = self.setdefault('_f_' + queue, [])
if allow_duplicate or (msg not in storage):
storage.append(msg)
@manage_changed
def pop_flash(self, queue=''):
storage = self.pop('_f_' + queue, [])
return storage
@manage_accessed
def peek_flash(self, queue=''):
storage = self.get('_f_' + queue, [])
return storage
# CSRF API methods
@manage_changed
def new_csrf_token(self):
token = text_(binascii.hexlify(os.urandom(20)))
self['_csrft_'] = token
return token
@manage_accessed
def get_csrf_token(self):
token = self.get('_csrft_', None)
if token is None:
token = self.new_csrf_token()
return token
# non-API methods
def _set_cookie(self, response):
if not self._cookie_on_exception:
exception = getattr(self.request, 'exception', None)
if (
exception is not None
): # dont set a cookie during exceptions
return False
cookieval = text_(
serializer.dumps((self.accessed, self.created, dict(self)))
)
if len(cookieval) > 4064:
raise ValueError(
'Cookie value is too long to store (%s bytes)'
% len(cookieval)
)
response.set_cookie(
self._cookie_name,
value=cookieval,
max_age=self._cookie_max_age,
path=self._cookie_path,
domain=self._cookie_domain,
secure=self._cookie_secure,
httponly=self._cookie_httponly,
samesite=self._cookie_samesite,
)
return True
return CookieSession
[docs]
def SignedCookieSessionFactory(
secret,
cookie_name='session',
max_age=None,
path='/',
domain=None,
secure=False,
httponly=False,
samesite='Lax',
set_on_exception=True,
timeout=1200,
reissue_time=0,
hashalg='sha512',
salt='pyramid.session.',
serializer=None,
):
"""
Configure a :term:`session factory` which will provide signed
cookie-based sessions. The return value of this
function is a :term:`session factory`, which may be provided as
the ``session_factory`` argument of a
:class:`pyramid.config.Configurator` constructor, or used
as the ``session_factory`` argument of the
:meth:`pyramid.config.Configurator.set_session_factory`
method.
The session factory returned by this function will create sessions
which are limited to storing fewer than 4000 bytes of data (as the
payload must fit into a single cookie).
Parameters:
``secret``
A string which is used to sign the cookie. The secret should be at
least as long as the block size of the selected hash algorithm. For
``sha512`` this would mean a 512 bit (64 character) secret. It should
be unique within the set of secret values provided to Pyramid for
its various subsystems (see :ref:`admonishment_against_secret_sharing`).
``hashalg``
The HMAC digest algorithm to use for signing. The algorithm must be
supported by the :mod:`hashlib` library. Default: ``'sha512'``.
``salt``
A namespace to avoid collisions between different uses of a shared
secret. Reusing a secret for different parts of an application is
strongly discouraged (see :ref:`admonishment_against_secret_sharing`).
Default: ``'pyramid.session.'``.
``cookie_name``
The name of the cookie used for sessioning. Default: ``'session'``.
``max_age``
The maximum age of the cookie used for sessioning (in seconds).
Default: ``None`` (browser scope).
``path``
The path used for the session cookie. Default: ``'/'``.
``domain``
The domain used for the session cookie. Default: ``None`` (no domain).
``secure``
The 'secure' flag of the session cookie. Default: ``False``.
``httponly``
Hide the cookie from Javascript by setting the 'HttpOnly' flag of the
session cookie. Default: ``False``.
``samesite``
The 'samesite' option of the session cookie. Set the value to ``None``
to turn off the samesite option. Default: ``'Lax'``.
``timeout``
A number of seconds of inactivity before a session times out. If
``None`` then the cookie never expires. This lifetime only applies
to the *value* within the cookie. Meaning that if the cookie expires
due to a lower ``max_age``, then this setting has no effect.
Default: ``1200``.
``reissue_time``
The number of seconds that must pass before the cookie is automatically
reissued as the result of accessing the session. The
duration is measured as the number of seconds since the last session
cookie was issued and 'now'. If this value is ``0``, a new cookie
will be reissued on every request accessing the session. If ``None``
then the cookie's lifetime will never be extended.
A good rule of thumb: if you want auto-expired cookies based on
inactivity: set the ``timeout`` value to 1200 (20 mins) and set the
``reissue_time`` value to perhaps a tenth of the ``timeout`` value
(120 or 2 mins). It's nonsensical to set the ``timeout`` value lower
than the ``reissue_time`` value, as the ticket will never be reissued.
However, such a configuration is not explicitly prevented.
Default: ``0``.
``set_on_exception``
If ``True``, set a session cookie even if an exception occurs
while rendering a view. Default: ``True``.
``serializer``
An object with two methods: ``loads`` and ``dumps``. The ``loads``
method should accept bytes and return a Python object. The ``dumps``
method should accept a Python object and return bytes. A ``ValueError``
should be raised for malformed inputs. If a serializer is not passed,
the :class:`pyramid.session.JSONSerializer` serializer will be used.
.. warning::
In :app:`Pyramid` 2.0 the default ``serializer`` option changed to
use :class:`pyramid.session.JSONSerializer`. See
:ref:`upgrading_session_20` for more information about why this
change was made.
.. versionadded: 1.5a3
.. versionchanged: 1.10
Added the ``samesite`` option and made the default ``Lax``.
.. versionchanged: 2.0
Changed the default ``serializer`` to be an instance of
:class:`pyramid.session.JSONSerializer`.
"""
if serializer is None:
serializer = JSONSerializer()
signed_serializer = SignedSerializer(
secret, salt, hashalg, serializer=serializer
)
return BaseCookieSessionFactory(
signed_serializer,
cookie_name=cookie_name,
max_age=max_age,
path=path,
domain=domain,
secure=secure,
httponly=httponly,
samesite=samesite,
timeout=timeout,
reissue_time=reissue_time,
set_on_exception=set_on_exception,
)
check_csrf_origin = check_csrf_origin # api
deprecated(
'check_csrf_origin',
'pyramid.session.check_csrf_origin is deprecated as of Pyramid '
'1.9. Use pyramid.csrf.check_csrf_origin instead.',
)
check_csrf_token = check_csrf_token # api
deprecated(
'check_csrf_token',
'pyramid.session.check_csrf_token is deprecated as of Pyramid '
'1.9. Use pyramid.csrf.check_csrf_token instead.',
)
