"""Session implementation for CherryPy. 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 Session object bound to cherrypy.session to store these variables. """ import datetime import os try: import cPickle as pickle except ImportError: import pickle import random try: # Python 2.5+ from hashlib import sha1 as sha except ImportError: from sha import new as sha import time import threading import types from warnings import warn import cherrypy from cherrypy.lib import httputil missing = object() class Session(object): """A CherryPy dict-like Session object (one per request).""" __metaclass__ = cherrypy._AttributeDocstrings _id = None id_observers = None id_observers__doc = "A list of callbacks to which to pass new id's." id__doc = "The current session ID." def _get_id(self): return self._id def _set_id(self, value): self._id = value for o in self.id_observers: o(value) id = property(_get_id, _set_id, doc=id__doc) timeout = 60 timeout__doc = "Number of minutes after which to delete session data." locked = False locked__doc = """ If True, this session instance has exclusive read/write access to session data.""" loaded = False loaded__doc = """ If True, data has been retrieved from storage. This should happen automatically on the first attempt to access session data.""" clean_thread = None clean_thread__doc = "Class-level Monitor which calls self.clean_up." clean_freq = 5 clean_freq__doc = "The poll rate for expired session cleanup in minutes." originalid = None originalid__doc = "The session id passed by the client. May be missing or unsafe." missing = False missing__doc = "True if the session requested by the client did not exist." regenerated = False regenerated__doc = """ True if the application called session.regenerate(). This is not set by internal calls to regenerate the session id.""" debug = False def __init__(self, id=None, **kwargs): self.id_observers = [] self._data = {} for k, v in kwargs.items(): setattr(self, k, v) self.originalid = id self.missing = False if id is None: if self.debug: cherrypy.log('No id given; making a new one', 'TOOLS.SESSIONS') self._regenerate() else: self.id = id if not self._exists(): if self.debug: cherrypy.log('Expired or malicious session %r; ' 'making a new one' % id, 'TOOLS.SESSIONS') # Expired or malicious session. Make a new one. # See http://www.cherrypy.org/ticket/709. self.id = None self.missing = True self._regenerate() def regenerate(self): """Replace the current session (with a new id).""" self.regenerated = True self._regenerate() def _regenerate(self): if self.id is not None: self.delete() old_session_was_locked = self.locked if old_session_was_locked: self.release_lock() self.id = None while self.id is None: self.id = self.generate_id() # Assert that the generated id is not already stored. if self._exists(): self.id = None if old_session_was_locked: self.acquire_lock() def clean_up(self): """Clean up expired sessions.""" pass try: os.urandom(20) except (AttributeError, NotImplementedError): # os.urandom not available until Python 2.4. Fall back to random.random. def generate_id(self): """Return a new session id.""" return sha('%s' % random.random()).hexdigest() else: def generate_id(self): """Return a new session id.""" return os.urandom(20).encode('hex') def save(self): """Save session data.""" try: # If session data has never been loaded then it's never been # accessed: no need to save it if self.loaded: t = datetime.timedelta(seconds=self.timeout * 60) expiration_time = datetime.datetime.now() + t if self.debug: cherrypy.log('Saving with expiry %s' % expiration_time, 'TOOLS.SESSIONS') self._save(expiration_time) finally: if self.locked: # Always release the lock if the user didn't release it self.release_lock() def load(self): """Copy stored session data into this session instance.""" data = self._load() # data is either None or a tuple (session_data, expiration_time) if data is None or data[1] < datetime.datetime.now(): if self.debug: cherrypy.log('Expired session, flushing data', 'TOOLS.SESSIONS') self._data = {} else: self._data = data[0] self.loaded = True # Stick the clean_thread in the class, not the instance. # The instances are created and destroyed per-request. cls = self.__class__ if self.clean_freq and not cls.clean_thread: # clean_up is in instancemethod and not a classmethod, # so that tool config can be accessed inside the method. t = cherrypy.process.plugins.Monitor( cherrypy.engine, self.clean_up, self.clean_freq * 60, name='Session cleanup') t.subscribe() cls.clean_thread = t t.start() def delete(self): """Delete stored session data.""" self._delete() def __getitem__(self, key): if not self.loaded: self.load() return self._data[key] def __setitem__(self, key, value): if not self.loaded: self.load() self._data[key] = value def __delitem__(self, key): if not self.loaded: self.load() del self._data[key] def pop(self, key, default=missing): """Remove the specified key and return the corresponding value. If key is not found, default is returned if given, otherwise KeyError is raised. """ if not self.loaded: self.load() if default is missing: return self._data.pop(key) else: return self._data.pop(key, default) def __contains__(self, key): if not self.loaded: self.load() return key in self._data def has_key(self, key): """D.has_key(k) -> True if D has a key k, else False.""" if not self.loaded: self.load() return key in self._data def get(self, key, default=None): """D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None.""" if not self.loaded: self.load() return self._data.get(key, default) def update(self, d): """D.update(E) -> None. Update D from E: for k in E: D[k] = E[k].""" if not self.loaded: self.load() self._data.update(d) def setdefault(self, key, default=None): """D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D.""" if not self.loaded: self.load() return self._data.setdefault(key, default) def clear(self): """D.clear() -> None. Remove all items from D.""" if not self.loaded: self.load() self._data.clear() def keys(self): """D.keys() -> list of D's keys.""" if not self.loaded: self.load() return self._data.keys() def items(self): """D.items() -> list of D's (key, value) pairs, as 2-tuples.""" if not self.loaded: self.load() return self._data.items() def values(self): """D.values() -> list of D's values.""" if not self.loaded: self.load() return self._data.values() class RamSession(Session): # Class-level objects. Don't rebind these! cache = {} locks = {} def clean_up(self): """Clean up expired sessions.""" now = datetime.datetime.now() for id, (data, expiration_time) in self.cache.items(): if expiration_time <= now: try: del self.cache[id] except KeyError: pass try: del self.locks[id] except KeyError: pass def _exists(self): return self.id in self.cache def _load(self): return self.cache.get(self.id) def _save(self, expiration_time): self.cache[self.id] = (self._data, expiration_time) def _delete(self): self.cache.pop(self.id, None) def acquire_lock(self): """Acquire an exclusive lock on the currently-loaded session data.""" self.locked = True self.locks.setdefault(self.id, threading.RLock()).acquire() def release_lock(self): """Release the lock on the currently-loaded session data.""" self.locks[self.id].release() self.locked = False def __len__(self): """Return the number of active sessions.""" return len(self.cache) class FileSession(Session): """Implementation of the File backend for sessions storage_path: the folder where session data will be saved. Each session will be saved as pickle.dump(data, expiration_time) in its own file; the filename will be self.SESSION_PREFIX + self.id. """ SESSION_PREFIX = 'session-' LOCK_SUFFIX = '.lock' pickle_protocol = pickle.HIGHEST_PROTOCOL def __init__(self, id=None, **kwargs): # The 'storage_path' arg is required for file-based sessions. kwargs['storage_path'] = os.path.abspath(kwargs['storage_path']) Session.__init__(self, id=id, **kwargs) def setup(cls, **kwargs): """Set up the storage system for file-based sessions. This should only be called once per process; this will be done automatically when using sessions.init (as the built-in Tool does). """ # The 'storage_path' arg is required for file-based sessions. kwargs['storage_path'] = os.path.abspath(kwargs['storage_path']) for k, v in kwargs.items(): setattr(cls, k, v) # Warn if any lock files exist at startup. lockfiles = [fname for fname in os.listdir(cls.storage_path) if (fname.startswith(cls.SESSION_PREFIX) and fname.endswith(cls.LOCK_SUFFIX))] if lockfiles: plural = ('', 's')[len(lockfiles) > 1] warn("%s session lockfile%s found at startup. If you are " "only running one process, then you may need to " "manually delete the lockfiles found at %r." % (len(lockfiles), plural, cls.storage_path)) setup = classmethod(setup) def _get_file_path(self): f = os.path.join(self.storage_path, self.SESSION_PREFIX + self.id) if not os.path.abspath(f).startswith(self.storage_path): raise cherrypy.HTTPError(400, "Invalid session id in cookie.") return f def _exists(self): path = self._get_file_path() return os.path.exists(path) def _load(self, path=None): if path is None: path = self._get_file_path() try: f = open(path, "rb") try: return pickle.load(f) finally: f.close() except (IOError, EOFError): return None def _save(self, expiration_time): f = open(self._get_file_path(), "wb") try: pickle.dump((self._data, expiration_time), f, self.pickle_protocol) finally: f.close() def _delete(self): try: os.unlink(self._get_file_path()) except OSError: pass def acquire_lock(self, path=None): """Acquire an exclusive lock on the currently-loaded session data.""" if path is None: path = self._get_file_path() path += self.LOCK_SUFFIX while True: try: lockfd = os.open(path, os.O_CREAT | os.O_WRONLY | os.O_EXCL) except OSError: time.sleep(0.1) else: os.close(lockfd) break self.locked = True def release_lock(self, path=None): """Release the lock on the currently-loaded session data.""" if path is None: path = self._get_file_path() os.unlink(path + self.LOCK_SUFFIX) self.locked = False def clean_up(self): """Clean up expired sessions.""" now = datetime.datetime.now() # Iterate over all session files in self.storage_path for fname in os.listdir(self.storage_path): if (fname.startswith(self.SESSION_PREFIX) and not fname.endswith(self.LOCK_SUFFIX)): # We have a session file: lock and load it and check # if it's expired. If it fails, nevermind. path = os.path.join(self.storage_path, fname) self.acquire_lock(path) try: contents = self._load(path) # _load returns None on IOError if contents is not None: data, expiration_time = contents if expiration_time < now: # Session expired: deleting it os.unlink(path) finally: self.release_lock(path) def __len__(self): """Return the number of active sessions.""" return len([fname for fname in os.listdir(self.storage_path) if (fname.startswith(self.SESSION_PREFIX) and not fname.endswith(self.LOCK_SUFFIX))]) class PostgresqlSession(Session): """ Implementation of the PostgreSQL backend for sessions. It assumes a table like this: create table session ( id varchar(40), data text, expiration_time timestamp ) You must provide your own get_db function. """ pickle_protocol = pickle.HIGHEST_PROTOCOL def __init__(self, id=None, **kwargs): Session.__init__(self, id, **kwargs) self.cursor = self.db.cursor() def setup(cls, **kwargs): """Set up the storage system for Postgres-based sessions. This should only be called once per process; this will be done automatically when using sessions.init (as the built-in Tool does). """ for k, v in kwargs.items(): setattr(cls, k, v) self.db = self.get_db() setup = classmethod(setup) def __del__(self): if self.cursor: self.cursor.close() self.db.commit() def _exists(self): # Select session data from table self.cursor.execute('select data, expiration_time from session ' 'where id=%s', (self.id,)) rows = self.cursor.fetchall() return bool(rows) def _load(self): # Select session data from table self.cursor.execute('select data, expiration_time from session ' 'where id=%s', (self.id,)) rows = self.cursor.fetchall() if not rows: return None pickled_data, expiration_time = rows[0] data = pickle.loads(pickled_data) return data, expiration_time def _save(self, expiration_time): pickled_data = pickle.dumps(self._data, self.pickle_protocol) self.cursor.execute('update session set data = %s, ' 'expiration_time = %s where id = %s', (pickled_data, expiration_time, self.id)) def _delete(self): self.cursor.execute('delete from session where id=%s', (self.id,)) def acquire_lock(self): """Acquire an exclusive lock on the currently-loaded session data.""" # We use the "for update" clause to lock the row self.locked = True self.cursor.execute('select id from session where id=%s for update', (self.id,)) def release_lock(self): """Release the lock on the currently-loaded session data.""" # We just close the cursor and that will remove the lock # introduced by the "for update" clause self.cursor.close() self.locked = False def clean_up(self): """Clean up expired sessions.""" self.cursor.execute('delete from session where expiration_time < %s', (datetime.datetime.now(),)) class MemcachedSession(Session): # The most popular memcached client for Python isn't thread-safe. # Wrap all .get and .set operations in a single lock. mc_lock = threading.RLock() # This is a seperate set of locks per session id. locks = {} servers = ['127.0.0.1:11211'] def setup(cls, **kwargs): """Set up the storage system for memcached-based sessions. This should only be called once per process; this will be done automatically when using sessions.init (as the built-in Tool does). """ for k, v in kwargs.items(): setattr(cls, k, v) import memcache cls.cache = memcache.Client(cls.servers) setup = classmethod(setup) def _exists(self): self.mc_lock.acquire() try: return bool(self.cache.get(self.id)) finally: self.mc_lock.release() def _load(self): self.mc_lock.acquire() try: return self.cache.get(self.id) finally: self.mc_lock.release() def _save(self, expiration_time): # Send the expiration time as "Unix time" (seconds since 1/1/1970) td = int(time.mktime(expiration_time.timetuple())) self.mc_lock.acquire() try: if not self.cache.set(self.id, (self._data, expiration_time), td): raise AssertionError("Session data for id %r not set." % self.id) finally: self.mc_lock.release() def _delete(self): self.cache.delete(self.id) def acquire_lock(self): """Acquire an exclusive lock on the currently-loaded session data.""" self.locked = True self.locks.setdefault(self.id, threading.RLock()).acquire() def release_lock(self): """Release the lock on the currently-loaded session data.""" self.locks[self.id].release() self.locked = False def __len__(self): """Return the number of active sessions.""" raise NotImplementedError # Hook functions (for CherryPy tools) def save(): """Save any changed session data.""" if not hasattr(cherrypy.serving, "session"): return request = cherrypy.serving.request response = cherrypy.serving.response # Guard against running twice if hasattr(request, "_sessionsaved"): return request._sessionsaved = True if response.stream: # If the body is being streamed, we have to save the data # *after* the response has been written out request.hooks.attach('on_end_request', cherrypy.session.save) else: # If the body is not being streamed, we save the data now # (so we can release the lock). if isinstance(response.body, types.GeneratorType): response.collapse_body() cherrypy.session.save() save.failsafe = True def close(): """Close the session object for this request.""" sess = getattr(cherrypy.serving, "session", None) if getattr(sess, "locked", False): # If the session is still locked we release the lock sess.release_lock() close.failsafe = True close.priority = 90 def init(storage_type='ram', path=None, path_header=None, name='session_id', timeout=60, domain=None, secure=False, clean_freq=5, persistent=True, debug=False, **kwargs): """Initialize session object (using cookies). storage_type: one of 'ram', 'file', 'postgresql'. This will be used to look up the corresponding class in cherrypy.lib.sessions globals. For example, 'file' will use the FileSession class. path: the 'path' value to stick in the response cookie metadata. path_header: if 'path' is None (the default), then the response cookie 'path' will be pulled from request.headers[path_header]. name: the name of the cookie. timeout: the expiration timeout (in minutes) for the stored session data. If 'persistent' is True (the default), this is also the timeout for the cookie. domain: the cookie domain. secure: if False (the default) the cookie 'secure' value will not be set. If True, the cookie 'secure' value will be set (to 1). clean_freq (minutes): the poll rate for expired session cleanup. persistent: if True (the default), the 'timeout' argument will be used to expire the cookie. If False, the cookie will not have an expiry, and the cookie will be a "session cookie" which expires when the browser is closed. Any additional kwargs will be bound to the new Session instance, and may be specific to the storage type. See the subclass of Session you're using for more information. """ request = cherrypy.serving.request # Guard against running twice if hasattr(request, "_session_init_flag"): return request._session_init_flag = True # Check if request came with a session ID id = None if name in request.cookie: id = request.cookie[name].value if debug: cherrypy.log('ID obtained from request.cookie: %r' % id, 'TOOLS.SESSIONS') # Find the storage class and call setup (first time only). storage_class = storage_type.title() + 'Session' storage_class = globals()[storage_class] if not hasattr(cherrypy, "session"): if hasattr(storage_class, "setup"): storage_class.setup(**kwargs) # Create and attach a new Session instance to cherrypy.serving. # It will possess a reference to (and lock, and lazily load) # the requested session data. kwargs['timeout'] = timeout kwargs['clean_freq'] = clean_freq cherrypy.serving.session = sess = storage_class(id, **kwargs) sess.debug = debug def update_cookie(id): """Update the cookie every time the session id changes.""" cherrypy.serving.response.cookie[name] = id sess.id_observers.append(update_cookie) # Create cherrypy.session which will proxy to cherrypy.serving.session if not hasattr(cherrypy, "session"): cherrypy.session = cherrypy._ThreadLocalProxy('session') if persistent: cookie_timeout = timeout else: # See http://support.microsoft.com/kb/223799/EN-US/ # and http://support.mozilla.com/en-US/kb/Cookies cookie_timeout = None set_response_cookie(path=path, path_header=path_header, name=name, timeout=cookie_timeout, domain=domain, secure=secure) def set_response_cookie(path=None, path_header=None, name='session_id', timeout=60, domain=None, secure=False): """Set a response cookie for the client. path: the 'path' value to stick in the response cookie metadata. path_header: if 'path' is None (the default), then the response cookie 'path' will be pulled from request.headers[path_header]. name: the name of the cookie. timeout: the expiration timeout for the cookie. If 0 or other boolean False, no 'expires' param will be set, and the cookie will be a "session cookie" which expires when the browser is closed. domain: the cookie domain. secure: if False (the default) the cookie 'secure' value will not be set. If True, the cookie 'secure' value will be set (to 1). """ # Set response cookie cookie = cherrypy.serving.response.cookie cookie[name] = cherrypy.serving.session.id cookie[name]['path'] = (path or cherrypy.serving.request.headers.get(path_header) or '/') # We'd like to use the "max-age" param as indicated in # http://www.faqs.org/rfcs/rfc2109.html 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[name]['max-age'] = timeout * 60 if timeout: e = time.time() + (timeout * 60) cookie[name]['expires'] = httputil.HTTPDate(e) if domain is not None: cookie[name]['domain'] = domain if secure: cookie[name]['secure'] = 1 def expire(): """Expire the current session cookie.""" name = cherrypy.serving.request.config.get('tools.sessions.name', 'session_id') one_year = 60 * 60 * 24 * 365 e = time.time() - one_year cherrypy.serving.response.cookie[name]['expires'] = httputil.HTTPDate(e)