/usr/share/pyshared/cherrypy/filters/sessionfilter.py is in python-cherrypy 2.3.0-3.
This file is owned by root:root, with mode 0o644.
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We use cherrypy.request to store some convenient variables as
well as data about the session for the current request. Instead of
polluting cherrypy.request we use a dummy object called
cherrypy.request._session (sess) to store these variables.
Variables used to store config options:
- sess.session_timeout: timeout delay for the session
- sess.session_locking: mechanism used to lock the session ('implicit' or 'explicit')
Variables used to store temporary variables:
- sess.session_storage (instance of the class implementing the backend)
Variables used to store the session for the current request:
- sess.session_data: dictionary containing the actual session data
- sess.session_id: current session ID
- sess.expiration_time: date/time when the current session will expire
Global variables (RAM backend only):
- cherrypy._session_lock_dict: dictionary containing the locks for all session_id
- cherrypy._session_data_holder: dictionary containing the data for all sessions
"""
import datetime
import os
try:
import cPickle as pickle
except ImportError:
import pickle
import random
import sha
import time
import thread
import threading
import types
import cherrypy
import basefilter
from cherrypy.lib import httptools
class EmptyClass:
""" An empty class """
pass
class SessionDeadlockError(Exception):
""" The session could not acquire a lock after a certain time """
pass
class SessionNotEnabledError(Exception):
""" User forgot to set session_filter.on to True """
pass
class SessionStoragePathNotConfiguredError(Exception):
"""
User set storage_type to file but forgot to set the storage_path
"""
pass
class SessionFilter(basefilter.BaseFilter):
def on_start_resource(self):
cherrypy.request._session = EmptyClass()
def before_request_body(self):
conf = cherrypy.config.get
sess = cherrypy.request._session
if not conf('session_filter.on', False):
sess.session_storage = None
return
sess.locked = False # Not locked by default
sess.to_be_loaded = True
# Read config options
sess.session_timeout = conf('session_filter.timeout', 60)
sess.session_locking = conf('session_filter.locking', 'explicit')
sess.on_create_session = conf('session_filter.on_create_session',
lambda data: None)
sess.on_renew_session = conf('session_filter.on_renew_session',
lambda data: None)
sess.on_delete_session = conf('session_filter.on_delete_session',
lambda data: None)
sess.generate_session_id = conf('session_filter.generate_session_id',
generate_session_id)
clean_up_delay = conf('session_filter.clean_up_delay', 5)
clean_up_delay = datetime.timedelta(seconds = clean_up_delay * 60)
cookie_name = conf('session_filter.cookie_name', 'session_id')
cookie_domain = conf('session_filter.cookie_domain', None)
cookie_secure = conf('session_filter.cookie_secure', False)
cookie_path = conf('session_filter.cookie_path', None)
if cookie_path is None:
cookie_path_header = conf('session_filter.cookie_path_from_header', None)
if cookie_path_header is not None:
cookie_path = cherrypy.request.headerMap.get(cookie_path_header, None)
if cookie_path is None:
cookie_path = '/'
sess.deadlock_timeout = conf('session_filter.deadlock_timeout', 30)
storage = conf('session_filter.storage_type', 'Ram')
storage = storage[0].upper() + storage[1:]
# People can set their own custom class
# through session_filter.storage_class
sess.session_storage = conf('session_filter.storage_class', None)
if sess.session_storage is None:
sess.session_storage = globals()[storage + 'Storage']()
else:
sess.session_storage = sess.session_storage()
now = datetime.datetime.now()
# Check if we need to clean up old sessions
if cherrypy._session_last_clean_up_time + clean_up_delay < now:
cherrypy._session_last_clean_up_time = now
# Run clean_up function in other thread to avoid blocking
# this request
thread.start_new_thread(sess.session_storage.clean_up, (sess,))
# Check if request came with a session ID
if cookie_name in cherrypy.request.simple_cookie:
# It did: we mark the data as needing to be loaded
sess.session_id = cherrypy.request.simple_cookie[cookie_name].value
# If using implicit locking, acquire lock
if sess.session_locking == 'implicit':
sess.session_data = {'_id': sess.session_id}
sess.session_storage.acquire_lock()
sess.to_be_loaded = True
else:
# No session_id yet
id = None
while id is None:
id = sess.generate_session_id()
# Assert that the generated id is not already stored.
if sess.session_storage.load(id) is not None:
id = None
sess.session_id = id
sess.session_data = {'_id': sess.session_id}
sess.on_create_session(sess.session_data)
# Set response cookie
cookie = cherrypy.response.simple_cookie
cookie[cookie_name] = sess.session_id
cookie[cookie_name]['path'] = cookie_path
# We'd like to use the "max-age" param as
# http://www.faqs.org/rfcs/rfc2109.html indicates but IE doesn't
# save it to disk and the session is lost if people close
# the browser
# So we have to use the old "expires" ... sigh ...
#cookie[cookie_name]['max-age'] = sess.session_timeout * 60
if sess.session_timeout:
gmt_expiration_time = time.gmtime(time.time() +
(sess.session_timeout * 60))
cookie[cookie_name]['expires'] = httptools.HTTPDate(gmt_expiration_time)
if cookie_domain is not None:
cookie[cookie_name]['domain'] = cookie_domain
if cookie_secure is True:
cookie[cookie_name]['secure'] = 1
def before_finalize(self):
def saveData(body, sess):
# If the body is a generator, we have to save the data
# *after* the generator has been consumed
if isinstance(body, types.GeneratorType):
for line in body:
yield line
# Save session data
if sess.to_be_loaded is False:
t = datetime.timedelta(seconds = sess.session_timeout * 60)
expiration_time = datetime.datetime.now() + t
sess.session_storage.save(sess.session_id,
sess.session_data, expiration_time)
else:
# If session data has never been loaded then it's never been
# accesses: not need to delete it
pass
if sess.locked:
# Always release the lock if the user didn't release it
sess.session_storage.release_lock()
# If the body is not a generator, we save the data
# before the body is returned
if not isinstance(body, types.GeneratorType):
for line in body:
yield line
sess = cherrypy.request._session
if not getattr(sess, 'session_storage', None):
# Sessions are not enabled: do nothing
return
# Make a wrapper around the body in order to save the session
# either before or after the body is returned
cherrypy.response.body = saveData(cherrypy.response.body, sess)
def on_end_request(self):
sess = cherrypy.request._session
if not getattr(sess, 'session_storage', None):
# Sessions are not enabled: do nothing
return
if getattr(sess, 'locked', None):
# If the session is still locked we release the lock
sess.session_storage.release_lock()
if getattr(sess, 'session_storage', None):
del sess.session_storage
class RamStorage:
""" Implementation of the RAM backend for sessions """
def load(self, id):
return cherrypy._session_data_holder.get(id)
def save(self, id, data, expiration_time):
cherrypy._session_data_holder[id] = (data, expiration_time)
def delete(self, id=None):
if id is None:
id = cherrypy.session.id
del cherrypy._session_data_holder[id]
def acquire_lock(self):
sess = cherrypy.request._session
id = cherrypy.session.id
lock = cherrypy._session_lock_dict.get(id)
if lock is None:
lock = threading.Lock()
cherrypy._session_lock_dict[id] = lock
startTime = time.time()
while True:
if lock.acquire(False):
break
if time.time() - startTime > sess.deadlock_timeout:
raise SessionDeadlockError()
time.sleep(0.5)
sess.locked = True
def release_lock(self):
sess = cherrypy.request._session
id = cherrypy.session['_id']
cherrypy._session_lock_dict[id].release()
sess.locked = False
def clean_up(self, sess):
to_be_deleted = []
now = datetime.datetime.now()
for id, (data, expiration_time) in cherrypy._session_data_holder.iteritems():
if expiration_time < now:
to_be_deleted.append(id)
for id in to_be_deleted:
try:
deleted_session = cherrypy._session_data_holder[id]
del cherrypy._session_data_holder[id]
sess.on_delete_session(deleted_session)
except KeyError:
# The session probably got deleted by a concurrent thread
# Safe to ignore this case
pass
class FileStorage:
""" Implementation of the File backend for sessions """
SESSION_PREFIX = 'session-'
LOCK_SUFFIX = '.lock'
def load(self, id):
file_path = self._get_file_path(id)
try:
f = open(file_path, "rb")
data = pickle.load(f)
f.close()
return data
except (IOError, EOFError):
return None
def save(self, id, data, expiration_time):
file_path = self._get_file_path(id)
f = open(file_path, "wb")
pickle.dump((data, expiration_time), f)
f.close()
def delete(self, id=None):
if id is None:
id = cherrypy.session.id
file_path = self._get_file_path(id)
try:
os.unlink(file_path)
except:
pass
def acquire_lock(self):
sess = cherrypy.request._session
if not sess.locked:
file_path = self._get_file_path(cherrypy.session.id)
self._lock_file(file_path + self.LOCK_SUFFIX)
sess.locked = True
def release_lock(self):
sess = cherrypy.request._session
file_path = self._get_file_path(cherrypy.session.id)
self._unlock_file(file_path + self.LOCK_SUFFIX)
sess.locked = False
def clean_up(self, sess):
storage_path = cherrypy.config.get('session_filter.storage_path')
if storage_path is None:
return
now = datetime.datetime.now()
# Iterate over all files in the dir/ and exclude non session files
# and lock files
for fname in os.listdir(storage_path):
if (fname.startswith(self.SESSION_PREFIX)
and not fname.endswith(self.LOCK_SUFFIX)):
# We have a session file: try to load it and check
# if it's expired. If it fails, nevermind.
file_path = os.path.join(storage_path, fname)
try:
f = open(file_path, "rb")
data, expiration_time = pickle.load(f)
f.close()
if expiration_time < now:
# Session expired: deleting it
id = fname[len(self.SESSION_PREFIX):]
sess.on_delete_session(data)
os.unlink(file_path)
except:
# We can't access the file ... nevermind
pass
def _get_file_path(self, id):
storage_path = cherrypy.config.get('session_filter.storage_path')
if storage_path is None:
raise SessionStoragePathNotConfiguredError()
fileName = self.SESSION_PREFIX + id
file_path = os.path.join(storage_path, fileName)
if not os.path.normpath(file_path).startswith(storage_path):
raise cherrypy.HTTPError(400, "Invalid session id in cookie.")
return file_path
def _lock_file(self, path):
sess = cherrypy.request._session
startTime = time.time()
while True:
try:
lockfd = os.open(path, os.O_CREAT|os.O_WRONLY|os.O_EXCL)
except OSError:
if time.time() - startTime > sess.deadlock_timeout:
raise SessionDeadlockError()
time.sleep(0.5)
else:
os.close(lockfd)
break
def _unlock_file(self, path):
os.unlink(path)
class PostgreSQLStorage:
""" Implementation of the PostgreSQL backend for sessions. It assumes
a table like this:
create table session (
id varchar(40),
data text,
expiration_time timestamp
)
"""
def __init__(self):
self.db = cherrypy.config.get('session_filter.get_db')()
self.cursor = self.db.cursor()
def __del__(self):
if self.cursor:
self.cursor.close()
self.db.commit()
def load(self, id):
# Select session data from table
self.cursor.execute(
'select data, expiration_time from session where id=%s',
(id,))
rows = self.cursor.fetchall()
if not rows:
return None
pickled_data, expiration_time = rows[0]
# Unpickle data
data = pickle.loads(pickled_data)
return (data, expiration_time)
def delete(self, id=None):
if id is None:
id = cherrypy.session.id
self.cursor.execute('delete from session where id=%s', (id,))
def save(self, id, data, expiration_time):
# Try to delete session if it was already there
self.cursor.execute(
'delete from session where id=%s',
(id,))
# Pickle data
pickled_data = pickle.dumps(data)
# Insert new session data
self.cursor.execute(
'insert into session (id, data, expiration_time) values (%s, %s, %s)',
(id, pickled_data, expiration_time))
def acquire_lock(self):
# We use the "for update" clause to lock the row
self.cursor.execute(
'select id from session where id=%s for update',
(cherrypy.session.id,))
def release_lock(self):
# We just close the cursor and that will remove the lock
# introduced by the "for update" clause
self.cursor.close()
self.cursor = None
def clean_up(self, sess):
now = datetime.datetime.now()
self.cursor.execute(
'select data from session where expiration_time < %s',
(now,))
rows = self.cursor.fetchall()
for row in rows:
sess.on_delete_session(row[0])
self.cursor.execute(
'delete from session where expiration_time < %s',
(now,))
try:
os.urandom(20)
except (AttributeError, NotImplementedError):
# os.urandom not available until Python 2.4. Fall back to random.random.
def generate_session_id():
"""Return a new session id."""
return sha.new('%s' % random.random()).hexdigest()
else:
def generate_session_id():
"""Return a new session id."""
return os.urandom(20).encode('hex')
generateSessionID = generate_session_id
# Users access sessions through cherrypy.session, but we want this
# to be thread-specific so we use a special wrapper that forwards
# calls to cherrypy.session to a thread-specific dictionary called
# cherrypy.request._session.session_data
class SessionWrapper:
def __getattr__(self, name):
sess = cherrypy.request._session
if sess.session_storage is None:
raise SessionNotEnabledError()
# Create thread-specific dictionary if needed
session_data = getattr(sess, 'session_data', None)
if session_data is None:
sess.session_data = {}
if name == 'acquire_lock':
return sess.session_storage.acquire_lock
elif name == 'release_lock':
return sess.session_storage.release_lock
elif name == 'id':
return sess.session_id
elif name == 'delete':
return sess.session_storage.delete
if sess.to_be_loaded:
data = sess.session_storage.load(sess.session_id)
# data is either None or a tuple (session_data, expiration_time)
if data is None or data[1] < datetime.datetime.now():
# Expired session:
# flush session data (but keep the same session_id)
sess.session_data = {'_id': sess.session_id}
if not (data is None):
sess.on_renew_session(sess.session_data)
else:
sess.session_data = data[0]
sess.to_be_loaded = False
return getattr(sess.session_data, name)
def expire():
"""Expire the current session cookie."""
name = cherrypy.config.get('session_filter.cookie_name', 'session_id')
one_year = 60 * 60 * 24 * 365
exp = time.gmtime(time.time() - one_year)
t = time.strftime("%a, %d-%b-%Y %H:%M:%S GMT", exp)
cherrypy.response.simple_cookie[name]['expires'] = t
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