diff options
Diffstat (limited to 'synapse/handlers/e2e_room_keys.py')
| -rw-r--r-- | synapse/handlers/e2e_room_keys.py | 88 |
1 files changed, 58 insertions, 30 deletions
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): |