| author |
Steve Losh <steve@stevelosh.com> |
| date |
Tue, 13 Oct 2009 18:34:55 -0400 |
| parents |
(none) |
| children |
(none) |
"""
Session Management
(from web.py)
"""
import os, time, datetime, random, base64
try:
import cPickle as pickle
except ImportError:
import pickle
try:
import hashlib
sha1 = hashlib.sha1
except ImportError:
import sha
sha1 = sha.new
import utils
import webapi as web
__all__ = [
'Session', 'SessionExpired',
'Store', 'DiskStore', 'DBStore',
]
web.config.session_parameters = utils.storage({
'cookie_name': 'webpy_session_id',
'cookie_domain': None,
'timeout': 86400, #24 * 60 * 60, # 24 hours in seconds
'ignore_expiry': True,
'ignore_change_ip': True,
'secret_key': 'fLjUfxqXtfNoIldA0A0J',
'expired_message': 'Session expired',
})
class SessionExpired(web.HTTPError):
def __init__(self, message):
web.HTTPError.__init__(self, '200 OK', {}, data=message)
class Session(utils.ThreadedDict):
"""Session management for web.py
"""
def __init__(self, app, store, initializer=None):
self.__dict__['store'] = store
self.__dict__['_initializer'] = initializer
self.__dict__['_last_cleanup_time'] = 0
self.__dict__['_config'] = utils.storage(web.config.session_parameters)
if app:
app.add_processor(self._processor)
def _processor(self, handler):
"""Application processor to setup session for every request"""
self._cleanup()
self._load()
try:
return handler()
finally:
self._save()
def _load(self):
"""Load the session from the store, by the id from cookie"""
cookie_name = self._config.cookie_name
cookie_domain = self._config.cookie_domain
self.session_id = web.cookies().get(cookie_name)
# protection against session_id tampering
if self.session_id and not self._valid_session_id(self.session_id):
self.session_id = None
self._check_expiry()
if self.session_id:
d = self.store[self.session_id]
self.update(d)
self._validate_ip()
if not self.session_id:
self.session_id = self._generate_session_id()
if self._initializer:
if isinstance(self._initializer, dict):
self.update(self._initializer)
elif hasattr(self._initializer, '__call__'):
self._initializer()
self.ip = web.ctx.ip
def _check_expiry(self):
# check for expiry
if self.session_id and self.session_id not in self.store:
if self._config.ignore_expiry:
self.session_id = None
else:
return self.expired()
def _validate_ip(self):
# check for change of IP
if self.session_id and self.get('ip', None) != web.ctx.ip:
if not self._config.ignore_change_ip:
return self.expired()
def _save(self):
cookie_name = self._config.cookie_name
cookie_domain = self._config.cookie_domain
if not self.get('_killed'):
web.setcookie(cookie_name, self.session_id, domain=cookie_domain)
self.store[self.session_id] = dict(self)
else:
web.setcookie(cookie_name, self.session_id, expires=-1, domain=cookie_domain)
def _generate_session_id(self):
"""Generate a random id for session"""
while True:
rand = os.urandom(16)
now = time.time()
secret_key = self._config.secret_key
session_id = sha1("%s%s%s%s" %(rand, now, utils.safestr(web.ctx.ip), secret_key))
session_id = session_id.hexdigest()
if session_id not in self.store:
break
return session_id
def _valid_session_id(self, session_id):
rx = utils.re_compile('^[0-9a-fA-F]+$')
return rx.match(session_id)
def _cleanup(self):
"""Cleanup the stored sessions"""
current_time = time.time()
timeout = self._config.timeout
if current_time - self._last_cleanup_time > timeout:
self.store.cleanup(timeout)
self.__dict__['_last_cleanup_time'] = current_time
def expired(self):
"""Called when an expired session is atime"""
self._killed = True
self._save()
raise SessionExpired(self._config.expired_message)
def kill(self):
"""Kill the session, make it no longer available"""
del self.store[self.session_id]
self._killed = True
class Store:
"""Base class for session stores"""
def __contains__(self, key):
raise NotImplementedError
def __getitem__(self, key):
raise NotImplementedError
def __setitem__(self, key, value):
raise NotImplementedError
def cleanup(self, timeout):
"""removes all the expired sessions"""
raise NotImplementedError
def encode(self, session_dict):
"""encodes session dict as a string"""
pickled = pickle.dumps(session_dict)
return base64.encodestring(pickled)
def decode(self, session_data):
"""decodes the data to get back the session dict """
pickled = base64.decodestring(session_data)
return pickle.loads(pickled)
class DiskStore(Store):
"""
Store for saving a session on disk.
>>> import tempfile
>>> root = tempfile.mkdtemp()
>>> s = DiskStore(root)
>>> s['a'] = 'foo'
>>> s['a']
'foo'
>>> time.sleep(0.01)
>>> s.cleanup(0.01)
>>> s['a']
Traceback (most recent call last):
...
KeyError: 'a'
"""
def __init__(self, root):
# if the storage root doesn't exists, create it.
if not os.path.exists(root):
os.mkdir(root)
self.root = root
def _get_path(self, key):
if os.path.sep in key:
raise ValueError, "Bad key: %s" % repr(key)
return os.path.join(self.root, key)
def __contains__(self, key):
path = self._get_path(key)
return os.path.exists(path)
def __getitem__(self, key):
path = self._get_path(key)
if os.path.exists(path):
pickled = open(path).read()
return self.decode(pickled)
else:
raise KeyError, key
def __setitem__(self, key, value):
path = self._get_path(key)
pickled = self.encode(value)
try:
f = open(path, 'w')
try:
f.write(pickled)
finally:
f.close()
except IOError:
pass
def __delitem__(self, key):
path = self._get_path(key)
if os.path.exists(path):
os.remove(path)
def cleanup(self, timeout):
now = time.time()
for f in os.listdir(self.root):
path = self._get_path(f)
atime = os.stat(path).st_atime
if now - atime > timeout :
os.remove(path)
class DBStore(Store):
"""Store for saving a session in database
Needs a table with the following columns:
session_id CHAR(128) UNIQUE NOT NULL,
atime DATETIME NOT NULL default current_timestamp,
data TEXT
"""
def __init__(self, db, table_name):
self.db = db
self.table = table_name
def __contains__(self, key):
data = self.db.select(self.table, where="session_id=$key", vars=locals())
return bool(list(data))
def __getitem__(self, key):
now = datetime.datetime.now()
try:
s = self.db.select(self.table, where="session_id=$key", vars=locals())[0]
self.db.update(self.table, where="session_id=$key", atime=now, vars=locals())
except IndexError:
raise KeyError
else:
return self.decode(s.data)
def __setitem__(self, key, value):
pickled = self.encode(value)
now = datetime.datetime.now()
if key in self:
self.db.update(self.table, where="session_id=$key", data=pickled, vars=locals())
else:
self.db.insert(self.table, False, session_id=key, data=pickled )
def __delitem__(self, key):
self.db.delete(self.table, where="session_id=$key", vars=locals())
def cleanup(self, timeout):
timeout = datetime.timedelta(timeout/(24.0*60*60)) #timedelta takes numdays as arg
last_allowed_time = datetime.datetime.now() - timeout
self.db.delete(self.table, where="$last_allowed_time > atime", vars=locals())
class ShelfStore:
"""Store for saving session using `shelve` module.
import shelve
store = ShelfStore(shelve.open('session.shelf'))
XXX: is shelve thread-safe?
"""
def __init__(self, shelf):
self.shelf = shelf
def __contains__(self, key):
return key in self.shelf
def __getitem__(self, key):
atime, v = self.shelf[key]
self[key] = v # update atime
return v
def __setitem__(self, key, value):
self.shelf[key] = time.time(), value
def __delitem__(self, key):
try:
del self.shelf[key]
except KeyError:
pass
def cleanup(self, timeout):
now = time.time()
for k in self.shelf.keys():
atime, v = self.shelf[k]
if now - atime > timeout :
del self[k]
if __name__ == '__main__' :
import doctest
doctest.testmod()