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authordrebs <drebs@leap.se>2016-04-26 09:23:48 -0300
committerdrebs <drebs@leap.se>2016-04-26 21:50:49 -0300
commitcf4453cb9325e7c6b3aec336fba1829c488a4442 (patch)
tree1bea41be5be567a84e550bb47e5047c78284c024 /server
parent129467d00e57f6cce34a8a4dc8b8b0e4a9b5e6e9 (diff)
[refactor] remove shared db locking from server
Diffstat (limited to 'server')
-rw-r--r--server/src/leap/soledad/server/__init__.py13
-rw-r--r--server/src/leap/soledad/server/auth.py5
-rw-r--r--server/src/leap/soledad/server/lock_resource.py231
3 files changed, 2 insertions, 247 deletions
diff --git a/server/src/leap/soledad/server/__init__.py b/server/src/leap/soledad/server/__init__.py
index 22894dac..43554eb4 100644
--- a/server/src/leap/soledad/server/__init__.py
+++ b/server/src/leap/soledad/server/__init__.py
@@ -49,9 +49,7 @@ synchronization is handled by the `leap.soledad.server.auth` module.
Shared database
---------------
-Each user may store password-encrypted recovery data in the shared database,
-as well as obtain a lock on the shared database in order to prevent creation
-of multiple secrets in parallel.
+Each user may store password-encrypted recovery data in the shared database.
Recovery documents are stored in the database without any information that
may identify the user. In order to achieve this, the doc_id of recovery
@@ -77,13 +75,8 @@ This has some implications:
* Because of the above, it is recommended that recovery documents expire
(not implemented yet) to prevent excess storage.
-Lock documents, on the other hand, may be more thoroughly protected by the
-server. Their doc_id's are calculated from the SHARED_DB_LOCK_DOC_ID_PREFIX
-and the user's uid.
-
The authorization for creating, updating, deleting and retrieving recovery
-and lock documents on the shared database is handled by
-`leap.soledad.server.auth` module.
+documents on the shared database is handled by `leap.soledad.server.auth` module.
"""
import configparser
@@ -96,7 +89,6 @@ from ._version import get_versions
from leap.soledad.server.auth import SoledadTokenAuthMiddleware
from leap.soledad.server.gzip_middleware import GzipMiddleware
-from leap.soledad.server.lock_resource import LockResource
from leap.soledad.server.sync import (
SyncResource,
MAX_REQUEST_SIZE,
@@ -155,7 +147,6 @@ http_app.url_to_resource.register(http_app.DocsResource)
http_app.url_to_resource.register(http_app.DocResource)
# register Soledad's new or modified resources
-http_app.url_to_resource.register(LockResource)
http_app.url_to_resource.register(SyncResource)
diff --git a/server/src/leap/soledad/server/auth.py b/server/src/leap/soledad/server/auth.py
index ccbd6fbd..0ce1f497 100644
--- a/server/src/leap/soledad/server/auth.py
+++ b/server/src/leap/soledad/server/auth.py
@@ -101,7 +101,6 @@ class URLToAuthorization(object):
/shared-db/docs | -
/shared-db/doc/{any_id} | GET, PUT, DELETE
/shared-db/sync-from/{source} | -
- /shared-db/lock/{uuid} | PUT, DELETE
/user-db | GET, PUT, DELETE
/user-db/docs | -
/user-db/doc/{id} | -
@@ -118,10 +117,6 @@ class URLToAuthorization(object):
'/%s/doc/{id:.*}' % SHARED_DB_NAME,
[self.HTTP_METHOD_GET, self.HTTP_METHOD_PUT,
self.HTTP_METHOD_DELETE])
- # auth info for shared-db lock resource
- self._register(
- '/%s/lock/%s' % (SHARED_DB_NAME, self._uuid),
- [self.HTTP_METHOD_PUT, self.HTTP_METHOD_DELETE])
# auth info for user-db database resource
self._register(
'/%s' % self._user_db_name,
diff --git a/server/src/leap/soledad/server/lock_resource.py b/server/src/leap/soledad/server/lock_resource.py
deleted file mode 100644
index 0a602e26..00000000
--- a/server/src/leap/soledad/server/lock_resource.py
+++ /dev/null
@@ -1,231 +0,0 @@
-# -*- coding: utf-8 -*-
-# lock_resource.py
-# Copyright (C) 2013 LEAP
-#
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program. If not, see <http://www.gnu.org/licenses/>.
-
-
-"""
-LockResource: a lock based on a document in the shared database.
-"""
-
-
-import hashlib
-import time
-import os
-import tempfile
-import errno
-
-
-from u1db.remote import http_app
-from twisted.python.lockfile import FilesystemLock
-
-
-from leap.soledad.common import (
- SHARED_DB_NAME,
- SHARED_DB_LOCK_DOC_ID_PREFIX,
-)
-from leap.soledad.common.errors import (
- InvalidTokenError,
- NotLockedError,
- AlreadyLockedError,
- LockTimedOutError,
- CouldNotObtainLockError,
-)
-
-
-class LockResource(object):
- """
- Handle requests for locking documents.
-
- This class uses Twisted's Filesystem lock to manage a lock in the shared
- database.
- """
-
- url_pattern = '/%s/lock/{uuid}' % SHARED_DB_NAME
- """
- """
-
- TIMEOUT = 300 # XXX is 5 minutes reasonable?
- """
- The timeout after which the lock expires.
- """
-
- # used for lock doc storage
- TIMESTAMP_KEY = '_timestamp'
- LOCK_TOKEN_KEY = '_token'
-
- FILESYSTEM_LOCK_TRIES = 5
- FILESYSTEM_LOCK_SLEEP_SECONDS = 1
-
- def __init__(self, uuid, state, responder):
- """
- Initialize the lock resource. Parameters to this constructor are
- automatically passed by u1db.
-
- :param uuid: The user unique id.
- :type uuid: str
- :param state: The backend database state.
- :type state: u1db.remote.ServerState
- :param responder: The infrastructure to send responses to client.
- :type responder: u1db.remote.HTTPResponder
- """
- self._shared_db = state.open_database(SHARED_DB_NAME)
- self._lock_doc_id = '%s%s' % (SHARED_DB_LOCK_DOC_ID_PREFIX, uuid)
- self._lock = FilesystemLock(
- os.path.join(
- tempfile.gettempdir(),
- hashlib.sha512(self._lock_doc_id).hexdigest()))
- self._state = state
- self._responder = responder
-
- @http_app.http_method(content=str)
- def put(self, content=None):
- """
- Handle a PUT request to the lock document.
-
- A lock is a document in the shared db with doc_id equal to
- 'lock-<uuid>' and the timestamp of its creation as content. This
- method obtains a threaded-lock and creates a lock document if it does
- not exist or if it has expired.
-
- It returns '201 Created' and a pair containing a token to unlock and
- the lock timeout, or '403 AlreadyLockedError' and the remaining amount
- of seconds the lock will still be valid.
-
- :param content: The content of the PUT request. It is only here
- because PUT requests with empty content are considered
- invalid requests by u1db.
- :type content: str
- """
- # obtain filesystem lock
- if not self._try_obtain_filesystem_lock():
- self._responder.send_response_json(
- LockTimedOutError.status, # error: request timeout
- error=LockTimedOutError.wire_description)
- return
-
- created_lock = False
- now = time.time()
- token = hashlib.sha256(os.urandom(10)).hexdigest() # for releasing
- lock_doc = self._shared_db.get_doc(self._lock_doc_id)
- remaining = self._remaining(lock_doc, now)
-
- # if there's no lock, create one
- if lock_doc is None:
- lock_doc = self._shared_db.create_doc(
- {
- self.TIMESTAMP_KEY: now,
- self.LOCK_TOKEN_KEY: token,
- },
- doc_id=self._lock_doc_id)
- created_lock = True
- else:
- if remaining == 0:
- # lock expired, create new one
- lock_doc.content = {
- self.TIMESTAMP_KEY: now,
- self.LOCK_TOKEN_KEY: token,
- }
- self._shared_db.put_doc(lock_doc)
- created_lock = True
-
- self._try_release_filesystem_lock()
-
- # send response to client
- if created_lock is True:
- self._responder.send_response_json(
- 201, timeout=self.TIMEOUT, token=token) # success: created
- else:
- self._responder.send_response_json(
- AlreadyLockedError.status, # error: forbidden
- error=AlreadyLockedError.wire_description, remaining=remaining)
-
- @http_app.http_method(token=str)
- def delete(self, token=None):
- """
- Delete the lock if the C{token} is valid.
-
- Delete the lock document in case C{token} is equal to the token stored
- in the lock document.
-
- :param token: The token returned when locking.
- :type token: str
-
- :raise NotLockedError: Raised in case the lock is not locked.
- :raise InvalidTokenError: Raised in case the token is invalid for
- unlocking.
- """
- lock_doc = self._shared_db.get_doc(self._lock_doc_id)
- if lock_doc is None or self._remaining(lock_doc, time.time()) == 0:
- self._responder.send_response_json(
- NotLockedError.status, # error: not found
- error=NotLockedError.wire_description)
- elif token != lock_doc.content[self.LOCK_TOKEN_KEY]:
- self._responder.send_response_json(
- InvalidTokenError.status, # error: unauthorized
- error=InvalidTokenError.wire_description)
- else:
- self._shared_db.delete_doc(lock_doc)
- # respond success: should use 204 but u1db does not support it.
- self._responder.send_response_json(200)
-
- def _remaining(self, lock_doc, now):
- """
- Return the number of seconds the lock contained in C{lock_doc} is
- still valid, when compared to C{now}.
-
- :param lock_doc: The document containing the lock.
- :type lock_doc: u1db.Document
- :param now: The time to which to compare the lock timestamp.
- :type now: float
-
- :return: The amount of seconds the lock is still valid.
- :rtype: float
- """
- if lock_doc is not None:
- lock_timestamp = lock_doc.content[self.TIMESTAMP_KEY]
- remaining = lock_timestamp + self.TIMEOUT - now
- return remaining if remaining > 0 else 0.0
- return 0.0
-
- def _try_obtain_filesystem_lock(self):
- """
- Try to obtain the file system lock.
-
- @return: Whether the lock was succesfully obtained.
- @rtype: bool
- """
- tries = self.FILESYSTEM_LOCK_TRIES
- while tries > 0:
- try:
- return self._lock.lock()
- except OSError as e:
- tries -= 1
- if tries == 0:
- raise CouldNotObtainLockError(e.message)
- time.sleep(self.FILESYSTEM_LOCK_SLEEP_SECONDS)
- return False
-
- def _try_release_filesystem_lock(self):
- """
- Release the filesystem lock.
- """
- try:
- self._lock.unlock()
- return True
- except OSError as e:
- if e.errno == errno.ENOENT:
- return True
- return False