diff --git a/synapse/handlers/e2e_room_keys.py b/synapse/handlers/e2e_room_keys.py
index bd58be6558..dda31fdd24 100644
--- a/synapse/handlers/e2e_room_keys.py
+++ b/synapse/handlers/e2e_room_keys.py
@@ -24,8 +24,21 @@ logger = logging.getLogger(__name__)
class E2eRoomKeysHandler(object):
+ """
+ Implements an optional realtime backup mechanism for encrypted E2E megolm room keys.
+ This gives a way for users to store and recover their megolm keys if they lose all
+ their clients. It should also extend easily to future room key mechanisms.
+ The actual payload of the encrypted keys is completely opaque to the handler.
+ """
+
def __init__(self, hs):
self.store = hs.get_datastore()
+
+ # Used to lock whenever a client is uploading key data. This prevents collisions
+ # between clients trying to upload the details of a new session, given all
+ # clients belonging to a user will receive and try to upload a new session at
+ # roughly the same time. Also used to lock out uploads when the key is being
+ # changed.
self._upload_linearizer = Linearizer("upload_room_keys_lock")
@defer.inlineCallbacks
@@ -40,33 +53,34 @@ class E2eRoomKeysHandler(object):
@defer.inlineCallbacks
def delete_room_keys(self, user_id, version, room_id, session_id):
- yield self.store.delete_e2e_room_keys(user_id, version, room_id, session_id)
+ # lock for consistency with uploading
+ with (yield self._upload_linearizer.queue(user_id)):
+ yield self.store.delete_e2e_room_keys(user_id, version, room_id, session_id)
@defer.inlineCallbacks
def upload_room_keys(self, user_id, version, room_keys):
# TODO: Validate the JSON to make sure it has the right keys.
- # Check that the version we're trying to upload is the current version
-
- try:
- version_info = yield self.get_version_info(user_id, version)
- except StoreError as e:
- if e.code == 404:
- raise SynapseError(404, "Version '%s' not found" % (version,))
- else:
- raise e
-
- if version_info['version'] != version:
- raise RoomKeysVersionError(current_version=version_info.version)
-
# XXX: perhaps we should use a finer grained lock here?
with (yield self._upload_linearizer.queue(user_id)):
-
- # go through the room_keys
- for room_id in room_keys['rooms']:
- for session_id in room_keys['rooms'][room_id]['sessions']:
- room_key = room_keys['rooms'][room_id]['sessions'][session_id]
+ # Check that the version we're trying to upload is the current version
+ try:
+ version_info = yield self.get_version_info(user_id, version)
+ except StoreError as e:
+ if e.code == 404:
+ raise SynapseError(404, "Version '%s' not found" % (version,))
+ else:
+ raise e
+
+ if version_info['version'] != version:
+ raise RoomKeysVersionError(current_version=version_info.version)
+
+ # go through the room_keys.
+ # XXX: this should/could be done concurrently, given we're in a lock.
+ for room_id, room in room_keys['rooms'].iteritems():
+ for session_id, session in room['sessions'].iteritems():
+ room_key = session[session_id]
yield self._upload_room_key(
user_id, version, room_id, session_id, room_key
@@ -86,10 +100,29 @@ class E2eRoomKeysHandler(object):
else:
raise e
- # check whether we merge or not. spelling it out with if/elifs rather
- # than lots of booleans for legibility.
- upsert = True
+ if _should_replace_room_key(current_room_key, room_key):
+ yield self.store.set_e2e_room_key(
+ user_id, version, room_id, session_id, room_key
+ )
+
+ def _should_replace_room_key(current_room_key, room_key):
+ """
+ Determine whether to replace the current_room_key in our backup for this
+ session (if any) with a new room_key that has been uploaded.
+
+ Args:
+ current_room_key (dict): Optional, the current room_key dict if any
+ room_key (dict): The new room_key dict which may or may not be fit to
+ replace the current_room_key
+
+ Returns:
+ True if current_room_key should be replaced by room_key in the backup
+ """
+
if current_room_key:
+ # spelt out with if/elifs rather than nested boolean expressions
+ # purely for legibility.
+
if room_key['is_verified'] and not current_room_key['is_verified']:
pass
elif (
@@ -97,16 +130,11 @@ class E2eRoomKeysHandler(object):
current_room_key['first_message_index']
):
pass
- elif room_key['forwarded_count'] < room_key['forwarded_count']:
+ elif room_key['forwarded_count'] < current_room_key['forwarded_count']:
pass
else:
- upsert = False
-
- # if so, we set the new room_key
- if upsert:
- yield self.store.set_e2e_room_key(
- user_id, version, room_id, session_id, room_key
- )
+ return False
+ return True
@defer.inlineCallbacks
def create_version(self, user_id, version_info):
|
