mirror of
https://github.com/pgadmin-org/pgadmin4.git
synced 2024-11-27 11:10:19 -06:00
013ad7446f
As sessions in pgAdmin4 are filesystem based session, they need locking for avoiding the access from multiple threads, specially running as an WSGI application. Fixes #3547
375 lines
11 KiB
Python
375 lines
11 KiB
Python
##########################################################################
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#
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# pgAdmin 4 - PostgreSQL Tools
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#
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# Copyright (C) 2013 - 2018, The pgAdmin Development Team
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# This software is released under the PostgreSQL Licence
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#
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##########################################################################
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"""
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Implements the server-side session management.
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Credit/Reference: http://flask.pocoo.org/snippets/109/
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Modified to support both Python 2.6+ & Python 3.x
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"""
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import base64
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import datetime
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import hmac
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import hashlib
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import os
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import random
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import string
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import time
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from uuid import uuid4
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from threading import Lock
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from flask import current_app, request, flash, redirect
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from flask_login import login_url
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from pgadmin.utils.ajax import make_json_response
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try:
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from cPickle import dump, load
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except ImportError:
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from pickle import dump, load
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try:
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from collections import OrderedDict
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except ImportError:
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from ordereddict import OrderedDict
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from flask.sessions import SessionInterface, SessionMixin
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from werkzeug.datastructures import CallbackDict
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def _calc_hmac(body, secret):
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return base64.b64encode(
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hmac.new(
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secret.encode(), body.encode(), hashlib.sha1
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).digest()
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).decode()
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sess_lock = Lock()
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class ManagedSession(CallbackDict, SessionMixin):
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def __init__(self, initial=None, sid=None, new=False, randval=None,
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hmac_digest=None):
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def on_update(self):
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self.modified = True
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CallbackDict.__init__(self, initial, on_update)
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self.sid = sid
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self.new = new
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self.modified = False
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self.randval = randval
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self.last_write = None
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self.force_write = False
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self.hmac_digest = hmac_digest
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def sign(self, secret):
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if not self.hmac_digest:
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if hasattr(string, 'lowercase'):
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population = string.lowercase
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# If script is running under python3
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elif hasattr(string, 'ascii_lowercase'):
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population = string.ascii_lowercase
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population += string.digits
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self.randval = ''.join(random.sample(population, 20))
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self.hmac_digest = _calc_hmac(
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'%s:%s' % (self.sid, self.randval), secret)
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class SessionManager(object):
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def new_session(self):
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'Create a new session'
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raise NotImplementedError
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def exists(self, sid):
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'Does the given session-id exist?'
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raise NotImplementedError
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def remove(self, sid):
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'Remove the session'
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raise NotImplementedError
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def get(self, sid, digest):
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'Retrieve a managed session by session-id, checking the HMAC digest'
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raise NotImplementedError
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def put(self, session):
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'Store a managed session'
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raise NotImplementedError
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class CachingSessionManager(SessionManager):
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def __init__(self, parent, num_to_store, skip_paths=[]):
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self.parent = parent
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self.num_to_store = num_to_store
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self._cache = OrderedDict()
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self.skip_paths = skip_paths
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def _normalize(self):
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if len(self._cache) > self.num_to_store:
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# Flush 20% of the cache
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with sess_lock:
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while len(self._cache) > (self.num_to_store * 0.8):
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self._cache.popitem(False)
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def new_session(self):
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session = self.parent.new_session()
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# Do not store the session if skip paths
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for sp in self.skip_paths:
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if request.path.startswith(sp):
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return session
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with sess_lock:
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self._cache[session.sid] = session
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self._normalize()
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return session
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def remove(self, sid):
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with sess_lock:
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self.parent.remove(sid)
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if sid in self._cache:
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del self._cache[sid]
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def exists(self, sid):
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with sess_lock:
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if sid in self._cache:
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return True
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return self.parent.exists(sid)
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def get(self, sid, digest):
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session = None
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with sess_lock:
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if sid in self._cache:
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session = self._cache[sid]
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if session.hmac_digest != digest:
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session = None
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# reset order in Dict
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del self._cache[sid]
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if not session:
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session = self.parent.get(sid, digest)
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# Do not store the session if skip paths
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for sp in self.skip_paths:
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if request.path.startswith(sp):
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return session
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self._cache[sid] = session
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self._normalize()
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return session
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def put(self, session):
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with sess_lock:
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self.parent.put(session)
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# Do not store the session if skip paths
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for sp in self.skip_paths:
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if request.path.startswith(sp):
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return
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if session.sid in self._cache:
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try:
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del self._cache[session.sid]
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except Exception:
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pass
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self._cache[session.sid] = session
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self._normalize()
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class FileBackedSessionManager(SessionManager):
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def __init__(self, path, secret, disk_write_delay, skip_paths=[]):
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self.path = path
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self.secret = secret
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self.disk_write_delay = disk_write_delay
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if not os.path.exists(self.path):
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os.makedirs(self.path)
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self.skip_paths = skip_paths
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def exists(self, sid):
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fname = os.path.join(self.path, sid)
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return os.path.exists(fname)
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def remove(self, sid):
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fname = os.path.join(self.path, sid)
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if os.path.exists(fname):
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os.unlink(fname)
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def new_session(self):
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sid = str(uuid4())
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fname = os.path.join(self.path, sid)
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while os.path.exists(fname):
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sid = str(uuid4())
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fname = os.path.join(self.path, sid)
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# Do not store the session if skip paths
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for sp in self.skip_paths:
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if request.path.startswith(sp):
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return ManagedSession(sid=sid)
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# touch the file
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with open(fname, 'wb'):
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pass
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return ManagedSession(sid=sid)
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def get(self, sid, digest):
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'Retrieve a managed session by session-id, checking the HMAC digest'
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fname = os.path.join(self.path, sid)
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data = None
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hmac_digest = None
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randval = None
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if os.path.exists(fname):
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try:
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with open(fname, 'rb') as f:
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randval, hmac_digest, data = load(f)
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except Exception:
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pass
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if not data:
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return self.new_session()
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# This assumes the file is correct, if you really want to
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# make sure the session is good from the server side, you
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# can re-calculate the hmac
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if hmac_digest != digest:
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return self.new_session()
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return ManagedSession(
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data, sid=sid, randval=randval, hmac_digest=hmac_digest
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)
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def put(self, session):
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"""Store a managed session"""
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current_time = time.time()
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if not session.hmac_digest:
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session.sign(self.secret)
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elif not session.force_write:
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if session.last_write is not None and \
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(current_time - float(session.last_write)) < \
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self.disk_write_delay:
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return
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session.last_write = current_time
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session.force_write = False
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# Do not store the session if skip paths
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for sp in self.skip_paths:
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if request.path.startswith(sp):
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return
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fname = os.path.join(self.path, session.sid)
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with open(fname, 'wb') as f:
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dump(
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(session.randval, session.hmac_digest, dict(session)),
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f
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)
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class ManagedSessionInterface(SessionInterface):
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def __init__(self, manager, cookie_timedelta):
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self.manager = manager
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self.cookie_timedelta = cookie_timedelta
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def get_expiration_time(self, app, session):
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if session.permanent:
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return app.permanent_session_lifetime
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return datetime.datetime.now() + self.cookie_timedelta
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def open_session(self, app, request):
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cookie_val = request.cookies.get(app.session_cookie_name)
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if not cookie_val or '!' not in cookie_val:
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return self.manager.new_session()
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sid, digest = cookie_val.split('!', 1)
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if self.manager.exists(sid):
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return self.manager.get(sid, digest)
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return self.manager.new_session()
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def save_session(self, app, session, response):
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domain = self.get_cookie_domain(app)
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if not session:
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self.manager.remove(session.sid)
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if session.modified:
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response.delete_cookie(app.session_cookie_name, domain=domain)
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return
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if not session.modified:
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# No need to save an unaltered session
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# TODO: put logic here to test if the cookie is older than N days,
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# if so, update the expiration date
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return
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self.manager.put(session)
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session.modified = False
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cookie_exp = self.get_expiration_time(app, session)
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response.set_cookie(
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app.session_cookie_name,
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'%s!%s' % (session.sid, session.hmac_digest),
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expires=cookie_exp, httponly=True, domain=domain
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)
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def create_session_interface(app, skip_paths=[]):
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return ManagedSessionInterface(
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CachingSessionManager(
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FileBackedSessionManager(
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app.config['SESSION_DB_PATH'],
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app.config['SECRET_KEY'],
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app.config.get('PGADMIN_SESSION_DISK_WRITE_DELAY', 10),
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skip_paths
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),
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1000,
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skip_paths
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),
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datetime.timedelta(days=1))
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def pga_unauthorised():
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lm = current_app.login_manager
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login_message = None
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if lm.login_message:
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if lm.localize_callback is not None:
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login_message = lm.localize_callback(lm.login_message)
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else:
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login_message = lm.login_message
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if not lm.login_view or request.is_xhr:
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# Only 401 is not enough to distinguish pgAdmin login is required.
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# There are other cases when we return 401. For eg. wrong password
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# supplied while connecting to server.
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# So send additional 'info' message.
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return make_json_response(
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status=401,
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success=0,
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errormsg=login_message,
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info='PGADMIN_LOGIN_REQUIRED'
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)
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if login_message:
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flash(login_message, category=lm.login_message_category)
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return redirect(login_url(lm.login_view, request.url))
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