# Copyright 2016 OpenMarket Ltd # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. import logging from http import HTTPStatus from typing import TYPE_CHECKING, Any, Dict, Optional from synapse.api.constants import EduTypes, EventContentFields, ToDeviceEventTypes from synapse.api.errors import Codes, SynapseError from synapse.api.ratelimiting import Ratelimiter from synapse.logging.context import run_in_background from synapse.logging.opentracing import ( SynapseTags, get_active_span_text_map, log_kv, set_tag, ) from synapse.replication.http.devices import ( ReplicationMultiUserDevicesResyncRestServlet, ) from synapse.types import JsonDict, Requester, StreamKeyType, UserID, get_domain_from_id from synapse.util import json_encoder from synapse.util.stringutils import random_string if TYPE_CHECKING: from synapse.server import HomeServer logger = logging.getLogger(__name__) class DeviceMessageHandler: def __init__(self, hs: "HomeServer"): """ Args: hs: server """ self.store = hs.get_datastores().main self.notifier = hs.get_notifier() self.is_mine = hs.is_mine if hs.config.experimental.msc3814_enabled: self.event_sources = hs.get_event_sources() self.device_handler = hs.get_device_handler() # We only need to poke the federation sender explicitly if its on the # same instance. Other federation sender instances will get notified by # `synapse.app.generic_worker.FederationSenderHandler` when it sees it # in the to-device replication stream. self.federation_sender = None if hs.should_send_federation(): self.federation_sender = hs.get_federation_sender() # If we can handle the to device EDUs we do so, otherwise we route them # to the appropriate worker. if hs.get_instance_name() in hs.config.worker.writers.to_device: hs.get_federation_registry().register_edu_handler( EduTypes.DIRECT_TO_DEVICE, self.on_direct_to_device_edu ) else: hs.get_federation_registry().register_instances_for_edu( EduTypes.DIRECT_TO_DEVICE, hs.config.worker.writers.to_device, ) # The handler to call when we think a user's device list might be out of # sync. We do all device list resyncing on the master instance, so if # we're on a worker we hit the device resync replication API. if hs.config.worker.worker_app is None: self._multi_user_device_resync = ( hs.get_device_handler().device_list_updater.multi_user_device_resync ) else: self._multi_user_device_resync = ( ReplicationMultiUserDevicesResyncRestServlet.make_client(hs) ) # a rate limiter for room key requests. The keys are # (sending_user_id, sending_device_id). self._ratelimiter = Ratelimiter( store=self.store, clock=hs.get_clock(), cfg=hs.config.ratelimiting.rc_key_requests, ) async def on_direct_to_device_edu(self, origin: str, content: JsonDict) -> None: """ Handle receiving to-device messages from remote homeservers. Args: origin: The remote homeserver. content: The JSON dictionary containing the to-device messages. """ local_messages = {} sender_user_id = content["sender"] if origin != get_domain_from_id(sender_user_id): logger.warning( "Dropping device message from %r with spoofed sender %r", origin, sender_user_id, ) message_type = content["type"] message_id = content["message_id"] for user_id, by_device in content["messages"].items(): # we use UserID.from_string to catch invalid user ids if not self.is_mine(UserID.from_string(user_id)): logger.warning("To-device message to non-local user %s", user_id) raise SynapseError(400, "Not a user here") if not by_device: continue # Ratelimit key requests by the sending user. if message_type == ToDeviceEventTypes.RoomKeyRequest: allowed, _ = await self._ratelimiter.can_do_action( None, (sender_user_id, None) ) if not allowed: logger.info( "Dropping room_key_request from %s to %s due to rate limit", sender_user_id, user_id, ) continue messages_by_device = { device_id: { "content": message_content, "type": message_type, "sender": sender_user_id, } for device_id, message_content in by_device.items() } local_messages[user_id] = messages_by_device await self._check_for_unknown_devices( message_type, sender_user_id, by_device ) # Add messages to the database. # Retrieve the stream id of the last-processed to-device message. last_stream_id = await self.store.add_messages_from_remote_to_device_inbox( origin, message_id, local_messages ) # Notify listeners that there are new to-device messages to process, # handing them the latest stream id. self.notifier.on_new_event( StreamKeyType.TO_DEVICE, last_stream_id, users=local_messages.keys() ) async def _check_for_unknown_devices( self, message_type: str, sender_user_id: str, by_device: Dict[str, Dict[str, Any]], ) -> None: """Checks inbound device messages for unknown remote devices, and if found marks the remote cache for the user as stale. """ if message_type != "m.room_key_request": return # Get the sending device IDs requesting_device_ids = set() for message_content in by_device.values(): device_id = message_content.get("requesting_device_id") requesting_device_ids.add(device_id) # Check if we are tracking the devices of the remote user. room_ids = await self.store.get_rooms_for_user(sender_user_id) if not room_ids: logger.info( "Received device message from remote device we don't" " share a room with: %s %s", sender_user_id, requesting_device_ids, ) return # If we are tracking check that we know about the sending # devices. cached_devices = await self.store.get_cached_devices_for_user(sender_user_id) unknown_devices = requesting_device_ids - set(cached_devices) if unknown_devices: logger.info( "Received device message from remote device not in our cache: %s %s", sender_user_id, unknown_devices, ) await self.store.mark_remote_users_device_caches_as_stale((sender_user_id,)) # Immediately attempt a resync in the background run_in_background(self._multi_user_device_resync, user_ids=[sender_user_id]) async def send_device_message( self, requester: Requester, message_type: str, messages: Dict[str, Dict[str, JsonDict]], ) -> None: """ Handle a request from a user to send to-device message(s). Args: requester: The user that is sending the to-device messages. message_type: The type of to-device messages that are being sent. messages: A dictionary containing recipients mapped to messages intended for them. """ sender_user_id = requester.user.to_string() set_tag(SynapseTags.TO_DEVICE_TYPE, message_type) set_tag(SynapseTags.TO_DEVICE_SENDER, sender_user_id) local_messages = {} remote_messages: Dict[str, Dict[str, Dict[str, JsonDict]]] = {} for user_id, by_device in messages.items(): # add an opentracing log entry for each message for device_id, message_content in by_device.items(): log_kv( { "event": "send_to_device_message", "user_id": user_id, "device_id": device_id, EventContentFields.TO_DEVICE_MSGID: message_content.get( EventContentFields.TO_DEVICE_MSGID ), } ) # Ratelimit local cross-user key requests by the sending device. if ( message_type == ToDeviceEventTypes.RoomKeyRequest and user_id != sender_user_id ): allowed, _ = await self._ratelimiter.can_do_action( requester, (sender_user_id, requester.device_id) ) if not allowed: log_kv({"message": f"dropping key requests to {user_id}"}) logger.info( "Dropping room_key_request from %s to %s due to rate limit", sender_user_id, user_id, ) continue # we use UserID.from_string to catch invalid user ids if self.is_mine(UserID.from_string(user_id)): messages_by_device = { device_id: { "content": message_content, "type": message_type, "sender": sender_user_id, } for device_id, message_content in by_device.items() } if messages_by_device: local_messages[user_id] = messages_by_device else: destination = get_domain_from_id(user_id) remote_messages.setdefault(destination, {})[user_id] = by_device context = get_active_span_text_map() remote_edu_contents = {} for destination, messages in remote_messages.items(): # The EDU contains a "message_id" property which is used for # idempotence. Make up a random one. message_id = random_string(16) log_kv({"destination": destination, "message_id": message_id}) remote_edu_contents[destination] = { "messages": messages, "sender": sender_user_id, "type": message_type, "message_id": message_id, "org.matrix.opentracing_context": json_encoder.encode(context), } # Add messages to the database. # Retrieve the stream id of the last-processed to-device message. last_stream_id = await self.store.add_messages_to_device_inbox( local_messages, remote_edu_contents ) # Notify listeners that there are new to-device messages to process, # handing them the latest stream id. self.notifier.on_new_event( StreamKeyType.TO_DEVICE, last_stream_id, users=local_messages.keys() ) if self.federation_sender: for destination in remote_messages.keys(): # Enqueue a new federation transaction to send the new # device messages to each remote destination. self.federation_sender.send_device_messages(destination) async def get_events_for_dehydrated_device( self, requester: Requester, device_id: str, since_token: Optional[str], limit: int, ) -> JsonDict: """Fetches up to `limit` events sent to `device_id` starting from `since_token` and returns the new since token. If there are no more messages, returns an empty array. Args: requester: the user requesting the messages device_id: ID of the dehydrated device since_token: stream id to start from when fetching messages limit: the number of messages to fetch Returns: A dict containing the to-device messages, as well as a token that the client can provide in the next call to fetch the next batch of messages """ user_id = requester.user.to_string() # only allow fetching messages for the dehydrated device id currently associated # with the user dehydrated_device = await self.device_handler.get_dehydrated_device(user_id) if dehydrated_device is None: raise SynapseError( HTTPStatus.FORBIDDEN, "No dehydrated device exists", Codes.FORBIDDEN, ) dehydrated_device_id, _ = dehydrated_device if device_id != dehydrated_device_id: raise SynapseError( HTTPStatus.FORBIDDEN, "You may only fetch messages for your dehydrated device", Codes.FORBIDDEN, ) since_stream_id = 0 if since_token: if not since_token.startswith("d"): raise SynapseError( HTTPStatus.BAD_REQUEST, "from parameter %r has an invalid format" % (since_token,), errcode=Codes.INVALID_PARAM, ) try: since_stream_id = int(since_token[1:]) except Exception: raise SynapseError( HTTPStatus.BAD_REQUEST, "from parameter %r has an invalid format" % (since_token,), errcode=Codes.INVALID_PARAM, ) to_token = self.event_sources.get_current_token().to_device_key messages, stream_id = await self.store.get_messages_for_device( user_id, device_id, since_stream_id, to_token, limit ) for message in messages: # Remove the message id before sending to client message_id = message.pop("message_id", None) if message_id: set_tag(SynapseTags.TO_DEVICE_EDU_ID, message_id) logger.debug( "Returning %d to-device messages between %d and %d (current token: %d) for " "dehydrated device %s, user_id %s", len(messages), since_stream_id, stream_id, to_token, device_id, user_id, ) return { "events": messages, "next_batch": f"d{stream_id}", }