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authordrebs <drebs@leap.se>2013-12-25 20:59:08 -0200
committerdrebs <drebs@leap.se>2014-01-20 16:42:26 -0200
commit75e9eb251100a2c0e5a93deedbc9fce67f7f1fe6 (patch)
tree0fc7c1916d72f334061b3864e703b09fddb76376 /server/src
parent83b0a1ca27d723022ea6ff58e52fde6fcbdb5aa4 (diff)
Move lock resource to its own file.
Diffstat (limited to 'server/src')
-rw-r--r--server/src/leap/soledad/server/__init__.py211
-rw-r--r--server/src/leap/soledad/server/lock_resource.py232
2 files changed, 235 insertions, 208 deletions
diff --git a/server/src/leap/soledad/server/__init__.py b/server/src/leap/soledad/server/__init__.py
index 26c33222..b2d55fcd 100644
--- a/server/src/leap/soledad/server/__init__.py
+++ b/server/src/leap/soledad/server/__init__.py
@@ -87,10 +87,6 @@ and lock documents on the shared database is handled by
"""
import configparser
-import time
-import hashlib
-import os
-import tempfile
from u1db.remote import http_app
@@ -99,10 +95,6 @@ from u1db.remote import http_app
from OpenSSL import tsafe
old_tsafe = tsafe
-from twisted.web.wsgi import WSGIResource
-from twisted.internet import reactor
-from twisted.internet.error import TimeoutError
-from twisted.python.lockfile import FilesystemLock
from twisted import version
if version.base() == "12.0.0":
# Put OpenSSL's tsafe back into place. This can probably be removed if we
@@ -112,19 +104,10 @@ if version.base() == "12.0.0":
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.common import (
- SHARED_DB_NAME,
- SHARED_DB_LOCK_DOC_ID_PREFIX,
-)
+from leap.soledad.common import SHARED_DB_NAME
from leap.soledad.common.couch import CouchServerState
-from leap.soledad.common.errors import (
- InvalidTokenError,
- NotLockedError,
- AlreadyLockedError,
- LockTimedOutError,
- CouldNotObtainLockError,
-)
#-----------------------------------------------------------------------------
@@ -159,195 +142,7 @@ class SoledadApp(http_app.HTTPApp):
return http_app.HTTPApp.__call__(self, environ, start_response)
-#
-# LockResource: a lock based on a document in the shared database.
-#
-
-@http_app.url_to_resource.register
-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}' % SoledadApp.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(SoledadApp.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:
- wire_descr = AlreadyLockedError.wire_description
- 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)
- self._responder.send_response_json(200) # success: should use 204
- # but u1db does not
- # support it.
-
- 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 Exception:
- return False
+http_app.url_to_resource.register(LockResource)
#-----------------------------------------------------------------------------
diff --git a/server/src/leap/soledad/server/lock_resource.py b/server/src/leap/soledad/server/lock_resource.py
new file mode 100644
index 00000000..a7870f77
--- /dev/null
+++ b/server/src/leap/soledad/server/lock_resource.py
@@ -0,0 +1,232 @@
+# -*- 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)
+ self._responder.send_response_json(200) # success: should use 204
+ # but u1db does not
+ # support it.
+
+ 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