source file: /Library/Python/2.3/site-packages/CherryPy-3.0.1-py2.3.egg/cherrypy/lib/sessions.py
file stats: 288 lines, 90 executed: 31.2% covered
   1. """Session implementation for CherryPy.
   2. 
   3. We use cherrypy.request to store some convenient variables as
   4. well as data about the session for the current request. Instead of
   5. polluting cherrypy.request we use a Session object bound to
   6. cherrypy.session to store these variables.
   7. """
   8. 
   9. import datetime
  10. import os
  11. try:
  12.     import cPickle as pickle
  13. except ImportError:
  14.     import pickle
  15. import random
  16. import sha
  17. import time
  18. import threading
  19. import types
  20. from warnings import warn
  21. 
  22. import cherrypy
  23. from cherrypy.lib import http
  24. 
  25. 
  26. class PerpetualTimer(threading._Timer):
  27. 
  28.     def run(self):
  29.         while True:
  30.             self.finished.wait(self.interval)
  31.             if self.finished.isSet():
  32.                 return
  33.             self.function(*self.args, **self.kwargs)
  34. 
  35. 
  36. missing = object()
  37. 
  38. class Session(object):
  39.     """A CherryPy dict-like Session object (one per request)."""
  40. 
  41.     __metaclass__ = cherrypy._AttributeDocstrings
  42. 
  43.     id = None
  44.     id__doc = "The current session ID."
  45. 
  46.     timeout = 60
  47.     timeout__doc = "Number of minutes after which to delete session data."
  48. 
  49.     locked = False
  50.     locked__doc = """
  51.     If True, this session instance has exclusive read/write access
  52.     to session data."""
  53. 
  54.     loaded = False
  55.     loaded__doc = """
  56.     If True, data has been retrieved from storage. This should happen
  57.     automatically on the first attempt to access session data."""
  58. 
  59.     clean_thread = None
  60.     clean_thread__doc = "Class-level PerpetualTimer which calls self.clean_up."
  61. 
  62.     clean_freq = 5
  63.     clean_freq__doc = "The poll rate for expired session cleanup in minutes."
  64. 
  65.     def __init__(self, id=None, **kwargs):
  66.         self._data = {}
  67. 
  68.         for k, v in kwargs.iteritems():
  69.             setattr(self, k, v)
  70. 
  71.         self.id = id
  72.         while self.id is None:
  73.             self.id = self.generate_id()
  74.             # Assert that the generated id is not already stored.
  75.             if self._load() is not None:
  76.                 self.id = None
  77. 
  78.     def clean_interrupt(cls):
  79.         """Stop the expired-session cleaning timer."""
  80.         if cls.clean_thread:
  81.             cls.clean_thread.cancel()
  82.             cls.clean_thread.join()
  83.             cls.clean_thread = None
  84.     clean_interrupt = classmethod(clean_interrupt)
  85. 
  86.     def clean_up(self):
  87.         """Clean up expired sessions."""
  88.         pass
  89. 
  90.     try:
  91.         os.urandom(20)
  92.     except (AttributeError, NotImplementedError):
  93.         # os.urandom not available until Python 2.4. Fall back to random.random.
  94.         def generate_id(self):
  95.             """Return a new session id."""
  96.             return sha.new('%s' % random.random()).hexdigest()
  97.     else:
  98.         def generate_id(self):
  99.             """Return a new session id."""
 100.             return os.urandom(20).encode('hex')
 101. 
 102.     def save(self):
 103.         """Save session data."""
 104.         try:
 105.             # If session data has never been loaded then it's never been
 106.             #   accessed: no need to delete it
 107.             if self.loaded:
 108.                 t = datetime.timedelta(seconds = self.timeout * 60)
 109.                 expiration_time = datetime.datetime.now() + t
 110.                 self._save(expiration_time)
 111. 
 112.         finally:
 113.             if self.locked:
 114.                 # Always release the lock if the user didn't release it
 115.                 self.release_lock()
 116. 
 117.     def load(self):
 118.         """Copy stored session data into this session instance."""
 119.         data = self._load()
 120.         # data is either None or a tuple (session_data, expiration_time)
 121.         if data is None or data[1] < datetime.datetime.now():
 122.             # Expired session: flush session data (but keep the same id)
 123.             self._data = {}
 124.         else:
 125.             self._data = data[0]
 126.         self.loaded = True
 127. 
 128.         # Stick the clean_thread in the class, not the instance.
 129.         # The instances are created and destroyed per-request.
 130.         cls = self.__class__
 131.         if not cls.clean_thread:
 132.             cherrypy.engine.on_stop_engine_list.append(cls.clean_interrupt)
 133.             # clean_up is in instancemethod and not a classmethod,
 134.             # so tool config can be accessed inside the method.
 135.             t = PerpetualTimer(self.clean_freq, self.clean_up)
 136.             t.setName("CP Session Cleanup")
 137.             cls.clean_thread = t
 138.             t.start()
 139. 
 140.     def delete(self):
 141.         """Delete stored session data."""
 142.         self._delete()
 143. 
 144.     def __getitem__(self, key):
 145.         if not self.loaded: self.load()
 146.         return self._data[key]
 147. 
 148.     def __setitem__(self, key, value):
 149.         if not self.loaded: self.load()
 150.         self._data[key] = value
 151. 
 152.     def __delitem__(self, key):
 153.         if not self.loaded: self.load()
 154.         del self._data[key]
 155. 
 156.     def pop(self, key, default=missing):
 157.         if not self.loaded: self.load()
 158.         if default is missing:
 159.             return self._data.pop(key)
 160.         else:
 161.             return self._data.pop(key, default)
 162. 
 163.     def __contains__(self, key):
 164.         if not self.loaded: self.load()
 165.         return key in self._data
 166. 
 167.     def has_key(self, key):
 168.         if not self.loaded: self.load()
 169.         return self._data.has_key(key)
 170. 
 171.     def get(self, key, default=None):
 172.         if not self.loaded: self.load()
 173.         return self._data.get(key, default)
 174. 
 175.     def update(self, d):
 176.         if not self.loaded: self.load()
 177.         self._data.update(d)
 178. 
 179.     def setdefault(self, key, default=None):
 180.         if not self.loaded: self.load()
 181.         return self._data.setdefault(key, default)
 182. 
 183.     def clear(self):
 184.         if not self.loaded: self.load()
 185.         self._data.clear()
 186. 
 187.     def keys(self):
 188.         if not self.loaded: self.load()
 189.         return self._data.keys()
 190. 
 191.     def items(self):
 192.         if not self.loaded: self.load()
 193.         return self._data.items()
 194. 
 195.     def values(self):
 196.         if not self.loaded: self.load()
 197.         return self._data.values()
 198. 
 199. 
 200. class RamSession(Session):
 201. 
 202.     # Class-level objects. Don't rebind these!
 203.     cache = {}
 204.     locks = {}
 205. 
 206.     def clean_up(self):
 207.         """Clean up expired sessions."""
 208.         now = datetime.datetime.now()
 209.         for id, (data, expiration_time) in self.cache.items():
 210.             if expiration_time < now:
 211.                 try:
 212.                     del self.cache[id]
 213.                 except KeyError:
 214.                     pass
 215.                 try:
 216.                     del self.locks[id]
 217.                 except KeyError:
 218.                     pass
 219. 
 220.     def _load(self):
 221.         return self.cache.get(self.id)
 222. 
 223.     def _save(self, expiration_time):
 224.         self.cache[self.id] = (self._data, expiration_time)
 225. 
 226.     def _delete(self):
 227.         del self.cache[self.id]
 228. 
 229.     def acquire_lock(self):
 230.         self.locked = True
 231.         self.locks.setdefault(self.id, threading.RLock()).acquire()
 232. 
 233.     def release_lock(self):
 234.         self.locks[self.id].release()
 235.         self.locked = False
 236. 
 237. 
 238. class FileSession(Session):
 239.     """ Implementation of the File backend for sessions
 240. 
 241.     storage_path: the folder where session data will be saved. Each session
 242.         will be saved as pickle.dump(data, expiration_time) in its own file;
 243.         the filename will be self.SESSION_PREFIX + self.id.
 244.     """
 245. 
 246.     SESSION_PREFIX = 'session-'
 247.     LOCK_SUFFIX = '.lock'
 248. 
 249.     def setup(self):
 250.         # Warn if any lock files exist at startup.
 251.         lockfiles = [fname for fname in os.listdir(self.storage_path)
 252.                      if (fname.startswith(self.SESSION_PREFIX)
 253.                          and fname.endswith(self.LOCK_SUFFIX))]
 254.         if lockfiles:
 255.             plural = ('', 's')[len(lockfiles) > 1]
 256.             warn("%s session lockfile%s found at startup. If you are "
 257.                  "only running one process, then you may need to "
 258.                  "manually delete the lockfiles found at %r."
 259.                  % (len(lockfiles), plural,
 260.                     os.path.abspath(self.storage_path)))
 261. 
 262.     def _get_file_path(self):
 263.         return os.path.join(self.storage_path, self.SESSION_PREFIX + self.id)
 264. 
 265.     def _load(self, path=None):
 266.         if path is None:
 267.             path = self._get_file_path()
 268.         try:
 269.             f = open(path, "rb")
 270.             try:
 271.                 return pickle.load(f)
 272.             finally:
 273.                 f.close()
 274.         except (IOError, EOFError):
 275.             return None
 276. 
 277.     def _save(self, expiration_time):
 278.         f = open(self._get_file_path(), "wb")
 279.         try:
 280.             pickle.dump((self._data, expiration_time), f)
 281.         finally:
 282.             f.close()
 283. 
 284.     def _delete(self):
 285.         try:
 286.             os.unlink(self._get_file_path())
 287.         except OSError:
 288.             pass
 289. 
 290.     def acquire_lock(self, path=None):
 291.         if path is None:
 292.             path = self._get_file_path()
 293.         path += self.LOCK_SUFFIX
 294.         while True:
 295.             try:
 296.                 lockfd = os.open(path, os.O_CREAT|os.O_WRONLY|os.O_EXCL)
 297.             except OSError:
 298.                 time.sleep(0.1)
 299.             else:
 300.                 os.close(lockfd)
 301.                 break
 302.         self.locked = True
 303. 
 304.     def release_lock(self, path=None):
 305.         if path is None:
 306.             path = self._get_file_path()
 307.         os.unlink(path + self.LOCK_SUFFIX)
 308.         self.locked = False
 309. 
 310.     def clean_up(self):
 311.         """Clean up expired sessions."""
 312.         now = datetime.datetime.now()
 313.         # Iterate over all session files in self.storage_path
 314.         for fname in os.listdir(self.storage_path):
 315.             if (fname.startswith(self.SESSION_PREFIX)
 316.                 and not fname.endswith(self.LOCK_SUFFIX)):
 317.                 # We have a session file: lock and load it and check
 318.                 #   if it's expired. If it fails, nevermind.
 319.                 path = os.path.join(self.storage_path, fname)
 320.                 self.acquire_lock(path)
 321.                 try:
 322.                     contents = self._load(path)
 323.                     # _load returns None on IOError
 324.                     if contents is not None:
 325.                         data, expiration_time = contents
 326.                         if expiration_time < now:
 327.                             # Session expired: deleting it
 328.                             os.unlink(path)
 329.                 finally:
 330.                     self.release_lock(path)
 331. 
 332. 
 333. class PostgresqlSession(Session):
 334.     """ Implementation of the PostgreSQL backend for sessions. It assumes
 335.         a table like this:
 336. 
 337.             create table session (
 338.                 id varchar(40),
 339.                 data text,
 340.                 expiration_time timestamp
 341.             )
 342. 
 343.     You must provide your own get_db function.
 344.     """
 345. 
 346.     def __init__(self):
 347.         self.db = self.get_db()
 348.         self.cursor = self.db.cursor()
 349. 
 350.     def __del__(self):
 351.         if self.cursor:
 352.             self.cursor.close()
 353.         self.db.commit()
 354. 
 355.     def _load(self):
 356.         # Select session data from table
 357.         self.cursor.execute('select data, expiration_time from session '
 358.                             'where id=%s', (self.id,))
 359.         rows = self.cursor.fetchall()
 360.         if not rows:
 361.             return None
 362. 
 363.         pickled_data, expiration_time = rows[0]
 364.         data = pickle.loads(pickled_data)
 365.         return data, expiration_time
 366. 
 367.     def _save(self, expiration_time):
 368.         pickled_data = pickle.dumps(self._data)
 369.         self.cursor.execute('update session set data = %s, '
 370.                             'expiration_time = %s where id = %s',
 371.                             (pickled_data, expiration_time, self.id))
 372. 
 373.     def _delete(self):
 374.         self.cursor.execute('delete from session where id=%s', (self.id,))
 375. 
 376.     def acquire_lock(self):
 377.         # We use the "for update" clause to lock the row
 378.         self.locked = True
 379.         self.cursor.execute('select id from session where id=%s for update',
 380.                             (self.id,))
 381. 
 382.     def release_lock(self):
 383.         # We just close the cursor and that will remove the lock
 384.         #   introduced by the "for update" clause
 385.         self.cursor.close()
 386.         self.locked = False
 387. 
 388.     def clean_up(self):
 389.         """Clean up expired sessions."""
 390.         self.cursor.execute('delete from session where expiration_time < %s',
 391.                             (datetime.datetime.now(),))
 392. 
 393. 
 394. # Hook functions (for CherryPy tools)
 395. 
 396. def save():
 397.     """Save any changed session data."""
 398.     # Guard against running twice
 399.     if hasattr(cherrypy.request, "_sessionsaved"):
 400.         return
 401.     cherrypy.request._sessionsaved = True
 402. 
 403.     if cherrypy.response.stream:
 404.         # If the body is being streamed, we have to save the data
 405.         #   *after* the response has been written out
 406.         cherrypy.request.hooks.attach('on_end_request', cherrypy.session.save)
 407.     else:
 408.         # If the body is not being streamed, we save the data now
 409.         # (so we can release the lock).
 410.         if isinstance(cherrypy.response.body, types.GeneratorType):
 411.             cherrypy.response.collapse_body()
 412.         cherrypy.session.save()
 413. save.failsafe = True
 414. 
 415. def close():
 416.     """Close the session object for this request."""
 417.     sess = cherrypy.session
 418.     if sess.locked:
 419.         # If the session is still locked we release the lock
 420.         sess.release_lock()
 421. close.failsafe = True
 422. close.priority = 90
 423. 
 424. 
 425. def init(storage_type='ram', path=None, path_header=None, name='session_id',
 426.          timeout=60, domain=None, secure=False, clean_freq=5, **kwargs):
 427.     """Initialize session object (using cookies).
 428. 
 429.     storage_type: one of 'ram', 'file', 'postgresql'. This will be used
 430.         to look up the corresponding class in cherrypy.lib.sessions
 431.         globals. For example, 'file' will use the FileSession class.
 432.     path: the 'path' value to stick in the response cookie metadata.
 433.     path_header: if 'path' is None (the default), then the response
 434.         cookie 'path' will be pulled from request.headers[path_header].
 435.     name: the name of the cookie.
 436.     timeout: the expiration timeout for the cookie.
 437.     domain: the cookie domain.
 438.     secure: if False (the default) the cookie 'secure' value will not
 439.         be set. If True, the cookie 'secure' value will be set (to 1).
 440.     clean_freq (minutes): the poll rate for expired session cleanup.
 441. 
 442.     Any additional kwargs will be bound to the new Session instance,
 443.     and may be specific to the storage type. See the subclass of Session
 444.     you're using for more information.
 445.     """
 446. 
 447.     request = cherrypy.request
 448. 
 449.     # Guard against running twice
 450.     if hasattr(request, "_session_init_flag"):
 451.         return
 452.     request._session_init_flag = True
 453. 
 454.     # Check if request came with a session ID
 455.     id = None
 456.     if name in request.cookie:
 457.         id = request.cookie[name].value
 458. 
 459.     # Create and attach a new Session instance to cherrypy._serving.
 460.     # It will possess a reference to (and lock, and lazily load)
 461.     # the requested session data.
 462.     storage_class = storage_type.title() + 'Session'
 463.     kwargs['timeout'] = timeout
 464.     kwargs['clean_freq'] = clean_freq
 465.     cherrypy._serving.session = sess = globals()[storage_class](id, **kwargs)
 466. 
 467.     if not hasattr(cherrypy, "session"):
 468.         cherrypy.session = cherrypy._ThreadLocalProxy('session')
 469.         if hasattr(sess, "setup"):
 470.             sess.setup()
 471. 
 472.     # Set response cookie
 473.     cookie = cherrypy.response.cookie
 474.     cookie[name] = sess.id
 475.     cookie[name]['path'] = path or request.headers.get(path_header) or '/'
 476. 
 477.     # We'd like to use the "max-age" param as indicated in
 478.     # http://www.faqs.org/rfcs/rfc2109.html but IE doesn't
 479.     # save it to disk and the session is lost if people close
 480.     # the browser. So we have to use the old "expires" ... sigh ...
 481. ##    cookie[name]['max-age'] = timeout * 60
 482.     if timeout:
 483.         cookie[name]['expires'] = http.HTTPDate(time.time() + (timeout * 60))
 484.     if domain is not None:
 485.         cookie[name]['domain'] = domain
 486.     if secure:
 487.         cookie[name]['secure'] = 1
 488. 
 489. def expire():
 490.     """Expire the current session cookie."""
 491.     name = cherrypy.request.config.get('tools.sessions.name', 'session_id')
 492.     one_year = 60 * 60 * 24 * 365
 493.     exp = time.gmtime(time.time() - one_year)
 494.     t = time.strftime("%a, %d-%b-%Y %H:%M:%S GMT", exp)
 495.     cherrypy.response.cookie[name]['expires'] = t
 496.