# Copyright 2015, 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 copy import itertools import logging from typing import ( TYPE_CHECKING, Any, Awaitable, Callable, Dict, Iterable, List, Mapping, Optional, Sequence, Tuple, TypeVar, Union, ) import attr from prometheus_client import Counter from twisted.internet import defer from twisted.internet.defer import Deferred from synapse.api.constants import EventTypes, Membership from synapse.api.errors import ( CodeMessageException, Codes, FederationDeniedError, HttpResponseException, SynapseError, UnsupportedRoomVersionError, ) from synapse.api.room_versions import ( KNOWN_ROOM_VERSIONS, EventFormatVersions, RoomVersion, RoomVersions, ) from synapse.events import EventBase, builder from synapse.federation.federation_base import FederationBase, event_from_pdu_json from synapse.logging.context import make_deferred_yieldable, preserve_fn from synapse.logging.utils import log_function from synapse.types import JsonDict, get_domain_from_id from synapse.util import unwrapFirstError from synapse.util.caches.expiringcache import ExpiringCache from synapse.util.retryutils import NotRetryingDestination if TYPE_CHECKING: from synapse.server import HomeServer logger = logging.getLogger(__name__) sent_queries_counter = Counter("synapse_federation_client_sent_queries", "", ["type"]) PDU_RETRY_TIME_MS = 1 * 60 * 1000 T = TypeVar("T") class InvalidResponseError(RuntimeError): """Helper for _try_destination_list: indicates that the server returned a response we couldn't parse """ pass class FederationClient(FederationBase): def __init__(self, hs: "HomeServer"): super().__init__(hs) self.pdu_destination_tried = {} # type: Dict[str, Dict[str, int]] self._clock.looping_call(self._clear_tried_cache, 60 * 1000) self.state = hs.get_state_handler() self.transport_layer = hs.get_federation_transport_client() self.hostname = hs.hostname self.signing_key = hs.signing_key self._get_pdu_cache = ExpiringCache( cache_name="get_pdu_cache", clock=self._clock, max_len=1000, expiry_ms=120 * 1000, reset_expiry_on_get=False, ) # type: ExpiringCache[str, EventBase] def _clear_tried_cache(self): """Clear pdu_destination_tried cache""" now = self._clock.time_msec() old_dict = self.pdu_destination_tried self.pdu_destination_tried = {} for event_id, destination_dict in old_dict.items(): destination_dict = { dest: time for dest, time in destination_dict.items() if time + PDU_RETRY_TIME_MS > now } if destination_dict: self.pdu_destination_tried[event_id] = destination_dict @log_function async def make_query( self, destination: str, query_type: str, args: dict, retry_on_dns_fail: bool = False, ignore_backoff: bool = False, ) -> JsonDict: """Sends a federation Query to a remote homeserver of the given type and arguments. Args: destination: Domain name of the remote homeserver query_type: Category of the query type; should match the handler name used in register_query_handler(). args: Mapping of strings to strings containing the details of the query request. ignore_backoff: true to ignore the historical backoff data and try the request anyway. Returns: The JSON object from the response """ sent_queries_counter.labels(query_type).inc() return await self.transport_layer.make_query( destination, query_type, args, retry_on_dns_fail=retry_on_dns_fail, ignore_backoff=ignore_backoff, ) @log_function async def query_client_keys( self, destination: str, content: JsonDict, timeout: int ) -> JsonDict: """Query device keys for a device hosted on a remote server. Args: destination: Domain name of the remote homeserver content: The query content. Returns: The JSON object from the response """ sent_queries_counter.labels("client_device_keys").inc() return await self.transport_layer.query_client_keys( destination, content, timeout ) @log_function async def query_user_devices( self, destination: str, user_id: str, timeout: int = 30000 ) -> JsonDict: """Query the device keys for a list of user ids hosted on a remote server. """ sent_queries_counter.labels("user_devices").inc() return await self.transport_layer.query_user_devices( destination, user_id, timeout ) @log_function async def claim_client_keys( self, destination: str, content: JsonDict, timeout: int ) -> JsonDict: """Claims one-time keys for a device hosted on a remote server. Args: destination: Domain name of the remote homeserver content: The query content. Returns: The JSON object from the response """ sent_queries_counter.labels("client_one_time_keys").inc() return await self.transport_layer.claim_client_keys( destination, content, timeout ) async def backfill( self, dest: str, room_id: str, limit: int, extremities: Iterable[str] ) -> Optional[List[EventBase]]: """Requests some more historic PDUs for the given room from the given destination server. Args: dest: The remote homeserver to ask. room_id: The room_id to backfill. limit: The maximum number of events to return. extremities: our current backwards extremities, to backfill from """ logger.debug("backfill extrem=%s", extremities) # If there are no extremities then we've (probably) reached the start. if not extremities: return None transaction_data = await self.transport_layer.backfill( dest, room_id, extremities, limit ) logger.debug("backfill transaction_data=%r", transaction_data) room_version = await self.store.get_room_version(room_id) pdus = [ event_from_pdu_json(p, room_version, outlier=False) for p in transaction_data["pdus"] ] # Check signatures and hash of pdus, removing any from the list that fail checks pdus[:] = await self._check_sigs_and_hash_and_fetch( dest, pdus, outlier=True, room_version=room_version ) return pdus async def get_pdu( self, destinations: Iterable[str], event_id: str, room_version: RoomVersion, outlier: bool = False, timeout: Optional[int] = None, ) -> Optional[EventBase]: """Requests the PDU with given origin and ID from the remote home servers. Will attempt to get the PDU from each destination in the list until one succeeds. Args: destinations: Which homeservers to query event_id: event to fetch room_version: version of the room outlier: Indicates whether the PDU is an `outlier`, i.e. if it's from an arbitrary point in the context as opposed to part of the current block of PDUs. Defaults to `False` timeout: How long to try (in ms) each destination for before moving to the next destination. None indicates no timeout. Returns: The requested PDU, or None if we were unable to find it. """ # TODO: Rate limit the number of times we try and get the same event. ev = self._get_pdu_cache.get(event_id) if ev: return ev pdu_attempts = self.pdu_destination_tried.setdefault(event_id, {}) signed_pdu = None for destination in destinations: now = self._clock.time_msec() last_attempt = pdu_attempts.get(destination, 0) if last_attempt + PDU_RETRY_TIME_MS > now: continue try: transaction_data = await self.transport_layer.get_event( destination, event_id, timeout=timeout ) logger.debug( "retrieved event id %s from %s: %r", event_id, destination, transaction_data, ) pdu_list = [ event_from_pdu_json(p, room_version, outlier=outlier) for p in transaction_data["pdus"] ] # type: List[EventBase] if pdu_list and pdu_list[0]: pdu = pdu_list[0] # Check signatures are correct. signed_pdu = await self._check_sigs_and_hash(room_version, pdu) break pdu_attempts[destination] = now except SynapseError as e: logger.info( "Failed to get PDU %s from %s because %s", event_id, destination, e ) continue except NotRetryingDestination as e: logger.info(str(e)) continue except FederationDeniedError as e: logger.info(str(e)) continue except Exception as e: pdu_attempts[destination] = now logger.info( "Failed to get PDU %s from %s because %s", event_id, destination, e ) continue if signed_pdu: self._get_pdu_cache[event_id] = signed_pdu return signed_pdu async def get_room_state_ids( self, destination: str, room_id: str, event_id: str ) -> Tuple[List[str], List[str]]: """Calls the /state_ids endpoint to fetch the state at a particular point in the room, and the auth events for the given event Returns: a tuple of (state event_ids, auth event_ids) """ result = await self.transport_layer.get_room_state_ids( destination, room_id, event_id=event_id ) state_event_ids = result["pdu_ids"] auth_event_ids = result.get("auth_chain_ids", []) if not isinstance(state_event_ids, list) or not isinstance( auth_event_ids, list ): raise Exception("invalid response from /state_ids") return state_event_ids, auth_event_ids async def _check_sigs_and_hash_and_fetch( self, origin: str, pdus: List[EventBase], room_version: RoomVersion, outlier: bool = False, include_none: bool = False, ) -> List[EventBase]: """Takes a list of PDUs and checks the signatures and hashes of each one. If a PDU fails its signature check then we check if we have it in the database and if not then request if from the originating server of that PDU. If a PDU fails its content hash check then it is redacted. The given list of PDUs are not modified, instead the function returns a new list. Args: origin pdu room_version outlier: Whether the events are outliers or not include_none: Whether to include None in the returned list for events that have failed their checks Returns: A list of PDUs that have valid signatures and hashes. """ deferreds = self._check_sigs_and_hashes(room_version, pdus) async def handle_check_result(pdu: EventBase, deferred: Deferred): try: res = await make_deferred_yieldable(deferred) except SynapseError: res = None if not res: # Check local db. res = await self.store.get_event( pdu.event_id, allow_rejected=True, allow_none=True ) pdu_origin = get_domain_from_id(pdu.sender) if not res and pdu_origin != origin: try: res = await self.get_pdu( destinations=[pdu_origin], event_id=pdu.event_id, room_version=room_version, outlier=outlier, timeout=10000, ) except SynapseError: pass if not res: logger.warning( "Failed to find copy of %s with valid signature", pdu.event_id ) return res handle = preserve_fn(handle_check_result) deferreds2 = [handle(pdu, deferred) for pdu, deferred in zip(pdus, deferreds)] valid_pdus = await make_deferred_yieldable( defer.gatherResults(deferreds2, consumeErrors=True) ).addErrback(unwrapFirstError) if include_none: return valid_pdus else: return [p for p in valid_pdus if p] async def get_event_auth( self, destination: str, room_id: str, event_id: str ) -> List[EventBase]: res = await self.transport_layer.get_event_auth(destination, room_id, event_id) room_version = await self.store.get_room_version(room_id) auth_chain = [ event_from_pdu_json(p, room_version, outlier=True) for p in res["auth_chain"] ] signed_auth = await self._check_sigs_and_hash_and_fetch( destination, auth_chain, outlier=True, room_version=room_version ) signed_auth.sort(key=lambda e: e.depth) return signed_auth async def _try_destination_list( self, description: str, destinations: Iterable[str], callback: Callable[[str], Awaitable[T]], failover_on_unknown_endpoint: bool = False, ) -> T: """Try an operation on a series of servers, until it succeeds Args: description: description of the operation we're doing, for logging destinations: list of server_names to try callback: Function to run for each server. Passed a single argument: the server_name to try. If the callback raises a CodeMessageException with a 300/400 code, attempts to perform the operation stop immediately and the exception is reraised. Otherwise, if the callback raises an Exception the error is logged and the next server tried. Normally the stacktrace is logged but this is suppressed if the exception is an InvalidResponseError. failover_on_unknown_endpoint: if True, we will try other servers if it looks like a server doesn't support the endpoint. This is typically useful if the endpoint in question is new or experimental. Returns: The result of callback, if it succeeds Raises: SynapseError if the chosen remote server returns a 300/400 code, or no servers were reachable. """ for destination in destinations: if destination == self.server_name: continue try: res = await callback(destination) return res except InvalidResponseError as e: logger.warning("Failed to %s via %s: %s", description, destination, e) except UnsupportedRoomVersionError: raise except HttpResponseException as e: synapse_error = e.to_synapse_error() failover = False if 500 <= e.code < 600: failover = True elif failover_on_unknown_endpoint: # there is no good way to detect an "unknown" endpoint. Dendrite # returns a 404 (with no body); synapse returns a 400 # with M_UNRECOGNISED. if e.code == 404 or ( e.code == 400 and synapse_error.errcode == Codes.UNRECOGNIZED ): failover = True if not failover: raise synapse_error from e logger.warning( "Failed to %s via %s: %i %s", description, destination, e.code, e.args[0], ) except Exception: logger.warning( "Failed to %s via %s", description, destination, exc_info=True ) raise SynapseError(502, "Failed to %s via any server" % (description,)) async def make_membership_event( self, destinations: Iterable[str], room_id: str, user_id: str, membership: str, content: dict, params: Optional[Mapping[str, Union[str, Iterable[str]]]], ) -> Tuple[str, EventBase, RoomVersion]: """ Creates an m.room.member event, with context, without participating in the room. Does so by asking one of the already participating servers to create an event with proper context. Returns a fully signed and hashed event. Note that this does not append any events to any graphs. Args: destinations: Candidate homeservers which are probably participating in the room. room_id: The room in which the event will happen. user_id: The user whose membership is being evented. membership: The "membership" property of the event. Must be one of "join" or "leave". content: Any additional data to put into the content field of the event. params: Query parameters to include in the request. Returns: `(origin, event, room_version)` where origin is the remote homeserver which generated the event, and room_version is the version of the room. Raises: UnsupportedRoomVersionError: if remote responds with a room version we don't understand. SynapseError: if the chosen remote server returns a 300/400 code. RuntimeError: if no servers were reachable. """ valid_memberships = {Membership.JOIN, Membership.LEAVE} if membership not in valid_memberships: raise RuntimeError( "make_membership_event called with membership='%s', must be one of %s" % (membership, ",".join(valid_memberships)) ) async def send_request(destination: str) -> Tuple[str, EventBase, RoomVersion]: ret = await self.transport_layer.make_membership_event( destination, room_id, user_id, membership, params ) # Note: If not supplied, the room version may be either v1 or v2, # however either way the event format version will be v1. room_version_id = ret.get("room_version", RoomVersions.V1.identifier) room_version = KNOWN_ROOM_VERSIONS.get(room_version_id) if not room_version: raise UnsupportedRoomVersionError() pdu_dict = ret.get("event", None) if not isinstance(pdu_dict, dict): raise InvalidResponseError("Bad 'event' field in response") logger.debug("Got response to make_%s: %s", membership, pdu_dict) pdu_dict["content"].update(content) # The protoevent received over the JSON wire may not have all # the required fields. Lets just gloss over that because # there's some we never care about if "prev_state" not in pdu_dict: pdu_dict["prev_state"] = [] ev = builder.create_local_event_from_event_dict( self._clock, self.hostname, self.signing_key, room_version=room_version, event_dict=pdu_dict, ) return destination, ev, room_version return await self._try_destination_list( "make_" + membership, destinations, send_request ) async def send_join( self, destinations: Iterable[str], pdu: EventBase, room_version: RoomVersion ) -> Dict[str, Any]: """Sends a join event to one of a list of homeservers. Doing so will cause the remote server to add the event to the graph, and send the event out to the rest of the federation. Args: destinations: Candidate homeservers which are probably participating in the room. pdu: event to be sent room_version: the version of the room (according to the server that did the make_join) Returns: a dict with members ``origin`` (a string giving the server the event was sent to, ``state`` (?) and ``auth_chain``. Raises: SynapseError: if the chosen remote server returns a 300/400 code. RuntimeError: if no servers were reachable. """ async def send_request(destination) -> Dict[str, Any]: content = await self._do_send_join(destination, pdu) logger.debug("Got content: %s", content) state = [ event_from_pdu_json(p, room_version, outlier=True) for p in content.get("state", []) ] auth_chain = [ event_from_pdu_json(p, room_version, outlier=True) for p in content.get("auth_chain", []) ] pdus = {p.event_id: p for p in itertools.chain(state, auth_chain)} create_event = None for e in state: if (e.type, e.state_key) == (EventTypes.Create, ""): create_event = e break if create_event is None: # If the state doesn't have a create event then the room is # invalid, and it would fail auth checks anyway. raise SynapseError(400, "No create event in state") # the room version should be sane. create_room_version = create_event.content.get( "room_version", RoomVersions.V1.identifier ) if create_room_version != room_version.identifier: # either the server that fulfilled the make_join, or the server that is # handling the send_join, is lying. raise InvalidResponseError( "Unexpected room version %s in create event" % (create_room_version,) ) valid_pdus = await self._check_sigs_and_hash_and_fetch( destination, list(pdus.values()), outlier=True, room_version=room_version, ) valid_pdus_map = {p.event_id: p for p in valid_pdus} # NB: We *need* to copy to ensure that we don't have multiple # references being passed on, as that causes... issues. signed_state = [ copy.copy(valid_pdus_map[p.event_id]) for p in state if p.event_id in valid_pdus_map ] signed_auth = [ valid_pdus_map[p.event_id] for p in auth_chain if p.event_id in valid_pdus_map ] # NB: We *need* to copy to ensure that we don't have multiple # references being passed on, as that causes... issues. for s in signed_state: s.internal_metadata = copy.deepcopy(s.internal_metadata) # double-check that the same create event has ended up in the auth chain auth_chain_create_events = [ e.event_id for e in signed_auth if (e.type, e.state_key) == (EventTypes.Create, "") ] if auth_chain_create_events != [create_event.event_id]: raise InvalidResponseError( "Unexpected create event(s) in auth chain: %s" % (auth_chain_create_events,) ) return { "state": signed_state, "auth_chain": signed_auth, "origin": destination, } return await self._try_destination_list("send_join", destinations, send_request) async def _do_send_join(self, destination: str, pdu: EventBase) -> JsonDict: time_now = self._clock.time_msec() try: return await self.transport_layer.send_join_v2( destination=destination, room_id=pdu.room_id, event_id=pdu.event_id, content=pdu.get_pdu_json(time_now), ) except HttpResponseException as e: if e.code in [400, 404]: err = e.to_synapse_error() # If we receive an error response that isn't a generic error, or an # unrecognised endpoint error, we assume that the remote understands # the v2 invite API and this is a legitimate error. if err.errcode not in [Codes.UNKNOWN, Codes.UNRECOGNIZED]: raise err else: raise e.to_synapse_error() logger.debug("Couldn't send_join with the v2 API, falling back to the v1 API") resp = await self.transport_layer.send_join_v1( destination=destination, room_id=pdu.room_id, event_id=pdu.event_id, content=pdu.get_pdu_json(time_now), ) # We expect the v1 API to respond with [200, content], so we only return the # content. return resp[1] async def send_invite( self, destination: str, room_id: str, event_id: str, pdu: EventBase, ) -> EventBase: room_version = await self.store.get_room_version(room_id) content = await self._do_send_invite(destination, pdu, room_version) pdu_dict = content["event"] logger.debug("Got response to send_invite: %s", pdu_dict) pdu = event_from_pdu_json(pdu_dict, room_version) # Check signatures are correct. pdu = await self._check_sigs_and_hash(room_version, pdu) # FIXME: We should handle signature failures more gracefully. return pdu async def _do_send_invite( self, destination: str, pdu: EventBase, room_version: RoomVersion ) -> JsonDict: """Actually sends the invite, first trying v2 API and falling back to v1 API if necessary. Returns: The event as a dict as returned by the remote server """ time_now = self._clock.time_msec() try: return await self.transport_layer.send_invite_v2( destination=destination, room_id=pdu.room_id, event_id=pdu.event_id, content={ "event": pdu.get_pdu_json(time_now), "room_version": room_version.identifier, "invite_room_state": pdu.unsigned.get("invite_room_state", []), }, ) except HttpResponseException as e: if e.code in [400, 404]: err = e.to_synapse_error() # If we receive an error response that isn't a generic error, we # assume that the remote understands the v2 invite API and this # is a legitimate error. if err.errcode != Codes.UNKNOWN: raise err # Otherwise, we assume that the remote server doesn't understand # the v2 invite API. That's ok provided the room uses old-style event # IDs. if room_version.event_format != EventFormatVersions.V1: raise SynapseError( 400, "User's homeserver does not support this room version", Codes.UNSUPPORTED_ROOM_VERSION, ) elif e.code in (403, 429): raise e.to_synapse_error() else: raise # Didn't work, try v1 API. # Note the v1 API returns a tuple of `(200, content)` _, content = await self.transport_layer.send_invite_v1( destination=destination, room_id=pdu.room_id, event_id=pdu.event_id, content=pdu.get_pdu_json(time_now), ) return content async def send_leave(self, destinations: Iterable[str], pdu: EventBase) -> None: """Sends a leave event to one of a list of homeservers. Doing so will cause the remote server to add the event to the graph, and send the event out to the rest of the federation. This is mostly useful to reject received invites. Args: destinations: Candidate homeservers which are probably participating in the room. pdu: event to be sent Raises: SynapseError if the chosen remote server returns a 300/400 code. RuntimeError if no servers were reachable. """ async def send_request(destination: str) -> None: content = await self._do_send_leave(destination, pdu) logger.debug("Got content: %s", content) return await self._try_destination_list( "send_leave", destinations, send_request ) async def _do_send_leave(self, destination: str, pdu: EventBase) -> JsonDict: time_now = self._clock.time_msec() try: return await self.transport_layer.send_leave_v2( destination=destination, room_id=pdu.room_id, event_id=pdu.event_id, content=pdu.get_pdu_json(time_now), ) except HttpResponseException as e: if e.code in [400, 404]: err = e.to_synapse_error() # If we receive an error response that isn't a generic error, or an # unrecognised endpoint error, we assume that the remote understands # the v2 invite API and this is a legitimate error. if err.errcode not in [Codes.UNKNOWN, Codes.UNRECOGNIZED]: raise err else: raise e.to_synapse_error() logger.debug("Couldn't send_leave with the v2 API, falling back to the v1 API") resp = await self.transport_layer.send_leave_v1( destination=destination, room_id=pdu.room_id, event_id=pdu.event_id, content=pdu.get_pdu_json(time_now), ) # We expect the v1 API to respond with [200, content], so we only return the # content. return resp[1] async def get_public_rooms( self, remote_server: str, limit: Optional[int] = None, since_token: Optional[str] = None, search_filter: Optional[Dict] = None, include_all_networks: bool = False, third_party_instance_id: Optional[str] = None, ) -> JsonDict: """Get the list of public rooms from a remote homeserver Args: remote_server: The name of the remote server limit: Maximum amount of rooms to return since_token: Used for result pagination search_filter: A filter dictionary to send the remote homeserver and filter the result set include_all_networks: Whether to include results from all third party instances third_party_instance_id: Whether to only include results from a specific third party instance Returns: The response from the remote server. Raises: HttpResponseException: There was an exception returned from the remote server SynapseException: M_FORBIDDEN when the remote server has disallowed publicRoom requests over federation """ return await self.transport_layer.get_public_rooms( remote_server, limit, since_token, search_filter, include_all_networks=include_all_networks, third_party_instance_id=third_party_instance_id, ) async def get_missing_events( self, destination: str, room_id: str, earliest_events_ids: Iterable[str], latest_events: Iterable[EventBase], limit: int, min_depth: int, timeout: int, ) -> List[EventBase]: """Tries to fetch events we are missing. This is called when we receive an event without having received all of its ancestors. Args: destination room_id earliest_events_ids: List of event ids. Effectively the events we expected to receive, but haven't. `get_missing_events` should only return events that didn't happen before these. latest_events: List of events we have received that we don't have all previous events for. limit: Maximum number of events to return. min_depth: Minimum depth of events to return. timeout: Max time to wait in ms """ try: content = await self.transport_layer.get_missing_events( destination=destination, room_id=room_id, earliest_events=earliest_events_ids, latest_events=[e.event_id for e in latest_events], limit=limit, min_depth=min_depth, timeout=timeout, ) room_version = await self.store.get_room_version(room_id) events = [ event_from_pdu_json(e, room_version) for e in content.get("events", []) ] signed_events = await self._check_sigs_and_hash_and_fetch( destination, events, outlier=False, room_version=room_version ) except HttpResponseException as e: if not e.code == 400: raise # We are probably hitting an old server that doesn't support # get_missing_events signed_events = [] return signed_events async def forward_third_party_invite( self, destinations: Iterable[str], room_id: str, event_dict: JsonDict ) -> None: for destination in destinations: if destination == self.server_name: continue try: await self.transport_layer.exchange_third_party_invite( destination=destination, room_id=room_id, event_dict=event_dict ) return except CodeMessageException: raise except Exception as e: logger.exception( "Failed to send_third_party_invite via %s: %s", destination, str(e) ) raise RuntimeError("Failed to send to any server.") async def get_room_complexity( self, destination: str, room_id: str ) -> Optional[JsonDict]: """ Fetch the complexity of a remote room from another server. Args: destination: The remote server room_id: The room ID to ask about. Returns: Dict contains the complexity metric versions, while None means we could not fetch the complexity. """ try: return await self.transport_layer.get_room_complexity( destination=destination, room_id=room_id ) except CodeMessageException as e: # We didn't manage to get it -- probably a 404. We are okay if other # servers don't give it to us. logger.debug( "Failed to fetch room complexity via %s for %s, got a %d", destination, room_id, e.code, ) except Exception: logger.exception( "Failed to fetch room complexity via %s for %s", destination, room_id ) # If we don't manage to find it, return None. It's not an error if a # server doesn't give it to us. return None async def get_space_summary( self, destinations: Iterable[str], room_id: str, suggested_only: bool, max_rooms_per_space: Optional[int], exclude_rooms: List[str], ) -> "FederationSpaceSummaryResult": """ Call other servers to get a summary of the given space Args: destinations: The remote servers. We will try them in turn, omitting any that have been blacklisted. room_id: ID of the space to be queried suggested_only: If true, ask the remote server to only return children with the "suggested" flag set max_rooms_per_space: A limit on the number of children to return for each space exclude_rooms: A list of room IDs to tell the remote server to skip Returns: a parsed FederationSpaceSummaryResult Raises: SynapseError if we were unable to get a valid summary from any of the remote servers """ async def send_request(destination: str) -> FederationSpaceSummaryResult: res = await self.transport_layer.get_space_summary( destination=destination, room_id=room_id, suggested_only=suggested_only, max_rooms_per_space=max_rooms_per_space, exclude_rooms=exclude_rooms, ) try: return FederationSpaceSummaryResult.from_json_dict(res) except ValueError as e: raise InvalidResponseError(str(e)) return await self._try_destination_list( "fetch space summary", destinations, send_request, failover_on_unknown_endpoint=True, ) @attr.s(frozen=True, slots=True) class FederationSpaceSummaryEventResult: """Represents a single event in the result of a successful get_space_summary call. It's essentially just a serialised event object, but we do a bit of parsing and validation in `from_json_dict` and store some of the validated properties in object attributes. """ event_type = attr.ib(type=str) state_key = attr.ib(type=str) via = attr.ib(type=Sequence[str]) # the raw data, including the above keys data = attr.ib(type=JsonDict) @classmethod def from_json_dict(cls, d: JsonDict) -> "FederationSpaceSummaryEventResult": """Parse an event within the result of a /spaces/ request Args: d: json object to be parsed Raises: ValueError if d is not a valid event """ event_type = d.get("type") if not isinstance(event_type, str): raise ValueError("Invalid event: 'event_type' must be a str") state_key = d.get("state_key") if not isinstance(state_key, str): raise ValueError("Invalid event: 'state_key' must be a str") content = d.get("content") if not isinstance(content, dict): raise ValueError("Invalid event: 'content' must be a dict") via = content.get("via") if not isinstance(via, Sequence): raise ValueError("Invalid event: 'via' must be a list") if any(not isinstance(v, str) for v in via): raise ValueError("Invalid event: 'via' must be a list of strings") return cls(event_type, state_key, via, d) @attr.s(frozen=True, slots=True) class FederationSpaceSummaryResult: """Represents the data returned by a successful get_space_summary call.""" rooms = attr.ib(type=Sequence[JsonDict]) events = attr.ib(type=Sequence[FederationSpaceSummaryEventResult]) @classmethod def from_json_dict(cls, d: JsonDict) -> "FederationSpaceSummaryResult": """Parse the result of a /spaces/ request Args: d: json object to be parsed Raises: ValueError if d is not a valid /spaces/ response """ rooms = d.get("rooms") if not isinstance(rooms, Sequence): raise ValueError("'rooms' must be a list") if any(not isinstance(r, dict) for r in rooms): raise ValueError("Invalid room in 'rooms' list") events = d.get("events") if not isinstance(events, Sequence): raise ValueError("'events' must be a list") if any(not isinstance(e, dict) for e in events): raise ValueError("Invalid event in 'events' list") parsed_events = [ FederationSpaceSummaryEventResult.from_json_dict(e) for e in events ] return cls(rooms, parsed_events)