348 lines
12 KiB
Python
348 lines
12 KiB
Python
# -*- coding: utf-8 -*-
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r"""
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werkzeug.contrib.sessions
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~~~~~~~~~~~~~~~~~~~~~~~~~
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This module contains some helper classes that help one to add session
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support to a python WSGI application. For full client-side session
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storage see :mod:`~werkzeug.contrib.securecookie` which implements a
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secure, client-side session storage.
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Application Integration
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=======================
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::
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from werkzeug.contrib.sessions import SessionMiddleware, \
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FilesystemSessionStore
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app = SessionMiddleware(app, FilesystemSessionStore())
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The current session will then appear in the WSGI environment as
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`werkzeug.session`. However it's recommended to not use the middleware
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but the stores directly in the application. However for very simple
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scripts a middleware for sessions could be sufficient.
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This module does not implement methods or ways to check if a session is
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expired. That should be done by a cronjob and storage specific. For
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example to prune unused filesystem sessions one could check the modified
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time of the files. It sessions are stored in the database the new()
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method should add an expiration timestamp for the session.
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For better flexibility it's recommended to not use the middleware but the
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store and session object directly in the application dispatching::
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session_store = FilesystemSessionStore()
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def application(environ, start_response):
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request = Request(environ)
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sid = request.cookies.get('cookie_name')
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if sid is None:
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request.session = session_store.new()
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else:
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request.session = session_store.get(sid)
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response = get_the_response_object(request)
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if request.session.should_save:
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session_store.save(request.session)
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response.set_cookie('cookie_name', request.session.sid)
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return response(environ, start_response)
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:copyright: (c) 2013 by the Werkzeug Team, see AUTHORS for more details.
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:license: BSD, see LICENSE for more details.
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"""
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import re
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import os
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import sys
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import tempfile
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from os import path
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from time import time
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from random import random
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from hashlib import sha1
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from pickle import dump, load, HIGHEST_PROTOCOL
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from werkzeug.datastructures import CallbackDict
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from werkzeug.utils import dump_cookie, parse_cookie
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from werkzeug.wsgi import ClosingIterator
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from werkzeug.posixemulation import rename
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from werkzeug._compat import PY2, text_type
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_sha1_re = re.compile(r'^[a-f0-9]{40}$')
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def _urandom():
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if hasattr(os, 'urandom'):
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return os.urandom(30)
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return random()
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def generate_key(salt=None):
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if salt is None:
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salt = repr(salt).encode('ascii')
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return sha1(b''.join([
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salt,
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str(time()).encode('ascii'),
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_urandom()
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])).hexdigest()
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class ModificationTrackingDict(CallbackDict):
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__slots__ = ('modified',)
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def __init__(self, *args, **kwargs):
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def on_update(self):
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self.modified = True
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self.modified = False
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CallbackDict.__init__(self, on_update=on_update)
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dict.update(self, *args, **kwargs)
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def copy(self):
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"""Create a flat copy of the dict."""
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missing = object()
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result = object.__new__(self.__class__)
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for name in self.__slots__:
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val = getattr(self, name, missing)
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if val is not missing:
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setattr(result, name, val)
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return result
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def __copy__(self):
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return self.copy()
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class Session(ModificationTrackingDict):
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"""Subclass of a dict that keeps track of direct object changes. Changes
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in mutable structures are not tracked, for those you have to set
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`modified` to `True` by hand.
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"""
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__slots__ = ModificationTrackingDict.__slots__ + ('sid', 'new')
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def __init__(self, data, sid, new=False):
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ModificationTrackingDict.__init__(self, data)
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self.sid = sid
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self.new = new
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def __repr__(self):
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return '<%s %s%s>' % (
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self.__class__.__name__,
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dict.__repr__(self),
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self.should_save and '*' or ''
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)
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@property
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def should_save(self):
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"""True if the session should be saved.
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.. versionchanged:: 0.6
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By default the session is now only saved if the session is
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modified, not if it is new like it was before.
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"""
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return self.modified
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class SessionStore(object):
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"""Baseclass for all session stores. The Werkzeug contrib module does not
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implement any useful stores besides the filesystem store, application
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developers are encouraged to create their own stores.
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:param session_class: The session class to use. Defaults to
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:class:`Session`.
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"""
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def __init__(self, session_class=None):
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if session_class is None:
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session_class = Session
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self.session_class = session_class
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def is_valid_key(self, key):
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"""Check if a key has the correct format."""
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return _sha1_re.match(key) is not None
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def generate_key(self, salt=None):
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"""Simple function that generates a new session key."""
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return generate_key(salt)
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def new(self):
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"""Generate a new session."""
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return self.session_class({}, self.generate_key(), True)
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def save(self, session):
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"""Save a session."""
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def save_if_modified(self, session):
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"""Save if a session class wants an update."""
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if session.should_save:
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self.save(session)
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def delete(self, session):
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"""Delete a session."""
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def get(self, sid):
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"""Get a session for this sid or a new session object. This method
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has to check if the session key is valid and create a new session if
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that wasn't the case.
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"""
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return self.session_class({}, sid, True)
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#: used for temporary files by the filesystem session store
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_fs_transaction_suffix = '.__wz_sess'
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class FilesystemSessionStore(SessionStore):
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"""Simple example session store that saves sessions on the filesystem.
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This store works best on POSIX systems and Windows Vista / Windows
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Server 2008 and newer.
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.. versionchanged:: 0.6
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`renew_missing` was added. Previously this was considered `True`,
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now the default changed to `False` and it can be explicitly
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deactivated.
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:param path: the path to the folder used for storing the sessions.
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If not provided the default temporary directory is used.
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:param filename_template: a string template used to give the session
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a filename. ``%s`` is replaced with the
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session id.
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:param session_class: The session class to use. Defaults to
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:class:`Session`.
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:param renew_missing: set to `True` if you want the store to
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give the user a new sid if the session was
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not yet saved.
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"""
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def __init__(self, path=None, filename_template='werkzeug_%s.sess',
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session_class=None, renew_missing=False, mode=0o644):
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SessionStore.__init__(self, session_class)
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if path is None:
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path = tempfile.gettempdir()
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self.path = path
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if isinstance(filename_template, text_type) and PY2:
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filename_template = filename_template.encode(
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sys.getfilesystemencoding() or 'utf-8')
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assert not filename_template.endswith(_fs_transaction_suffix), \
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'filename templates may not end with %s' % _fs_transaction_suffix
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self.filename_template = filename_template
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self.renew_missing = renew_missing
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self.mode = mode
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def get_session_filename(self, sid):
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# out of the box, this should be a strict ASCII subset but
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# you might reconfigure the session object to have a more
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# arbitrary string.
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if isinstance(sid, text_type) and PY2:
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sid = sid.encode(sys.getfilesystemencoding() or 'utf-8')
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return path.join(self.path, self.filename_template % sid)
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def save(self, session):
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fn = self.get_session_filename(session.sid)
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fd, tmp = tempfile.mkstemp(suffix=_fs_transaction_suffix,
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dir=self.path)
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f = os.fdopen(fd, 'wb')
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try:
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dump(dict(session), f, HIGHEST_PROTOCOL)
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finally:
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f.close()
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try:
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rename(tmp, fn)
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os.chmod(fn, self.mode)
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except (IOError, OSError):
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pass
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def delete(self, session):
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fn = self.get_session_filename(session.sid)
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try:
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os.unlink(fn)
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except OSError:
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pass
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def get(self, sid):
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if not self.is_valid_key(sid):
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return self.new()
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try:
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f = open(self.get_session_filename(sid), 'rb')
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except IOError:
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if self.renew_missing:
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return self.new()
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data = {}
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else:
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try:
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try:
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data = load(f)
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except Exception:
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data = {}
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finally:
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f.close()
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return self.session_class(data, sid, False)
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def list(self):
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"""Lists all sessions in the store.
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.. versionadded:: 0.6
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"""
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before, after = self.filename_template.split('%s', 1)
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filename_re = re.compile(r'%s(.{5,})%s$' % (re.escape(before),
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re.escape(after)))
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result = []
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for filename in os.listdir(self.path):
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#: this is a session that is still being saved.
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if filename.endswith(_fs_transaction_suffix):
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continue
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match = filename_re.match(filename)
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if match is not None:
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result.append(match.group(1))
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return result
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class SessionMiddleware(object):
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"""A simple middleware that puts the session object of a store provided
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into the WSGI environ. It automatically sets cookies and restores
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sessions.
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However a middleware is not the preferred solution because it won't be as
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fast as sessions managed by the application itself and will put a key into
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the WSGI environment only relevant for the application which is against
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the concept of WSGI.
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The cookie parameters are the same as for the :func:`~dump_cookie`
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function just prefixed with ``cookie_``. Additionally `max_age` is
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called `cookie_age` and not `cookie_max_age` because of backwards
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compatibility.
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"""
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def __init__(self, app, store, cookie_name='session_id',
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cookie_age=None, cookie_expires=None, cookie_path='/',
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cookie_domain=None, cookie_secure=None,
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cookie_httponly=False, environ_key='werkzeug.session'):
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self.app = app
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self.store = store
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self.cookie_name = cookie_name
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self.cookie_age = cookie_age
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self.cookie_expires = cookie_expires
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self.cookie_path = cookie_path
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self.cookie_domain = cookie_domain
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self.cookie_secure = cookie_secure
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self.cookie_httponly = cookie_httponly
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self.environ_key = environ_key
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def __call__(self, environ, start_response):
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cookie = parse_cookie(environ.get('HTTP_COOKIE', ''))
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sid = cookie.get(self.cookie_name, None)
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if sid is None:
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session = self.store.new()
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else:
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session = self.store.get(sid)
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environ[self.environ_key] = session
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def injecting_start_response(status, headers, exc_info=None):
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if session.should_save:
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self.store.save(session)
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headers.append(('Set-Cookie', dump_cookie(self.cookie_name,
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session.sid, self.cookie_age,
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self.cookie_expires, self.cookie_path,
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self.cookie_domain, self.cookie_secure,
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self.cookie_httponly)))
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return start_response(status, headers, exc_info)
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return ClosingIterator(self.app(environ, injecting_start_response),
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lambda: self.store.save_if_modified(session))
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