# Copyright 2015-2022 The Matrix.org Foundation C.I.C. # Copyright 2020 Sorunome # # 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, Awaitable, Callable, Collection, Container, Dict, Iterable, List, Mapping, Optional, Sequence, Tuple, TypeVar, Union, ) import attr from prometheus_client import Counter from synapse.api.constants import EventContentFields, EventTypes, Membership from synapse.api.errors import ( CodeMessageException, Codes, FederationDeniedError, HttpResponseException, RequestSendFailed, SynapseError, UnsupportedRoomVersionError, ) from synapse.api.room_versions import ( KNOWN_ROOM_VERSIONS, EventFormatVersions, RoomVersion, RoomVersions, ) from synapse.events import EventBase, builder, make_event_from_dict from synapse.federation.federation_base import ( FederationBase, InvalidEventSignatureError, event_from_pdu_json, ) from synapse.federation.transport.client import SendJoinResponse from synapse.http.types import QueryParams from synapse.logging.opentracing import SynapseTags, log_kv, set_tag, tag_args, trace from synapse.types import JsonDict, UserID, get_domain_from_id from synapse.util.async_helpers import concurrently_execute 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") @attr.s(frozen=True, slots=True, auto_attribs=True) class PulledPduInfo: """ A result object that stores the PDU and info about it like which homeserver we pulled it from (`pull_origin`) """ pdu: EventBase # Which homeserver we pulled the PDU from pull_origin: str class InvalidResponseError(RuntimeError): """Helper for _try_destination_list: indicates that the server returned a response we couldn't parse """ @attr.s(slots=True, frozen=True, auto_attribs=True) class SendJoinResult: # The event to persist. event: EventBase # A string giving the server the event was sent to. origin: str state: List[EventBase] auth_chain: List[EventBase] # True if 'state' elides non-critical membership events partial_state: bool # if 'partial_state' is set, a list of the servers in the room (otherwise empty) servers_in_room: List[str] class FederationClient(FederationBase): def __init__(self, hs: "HomeServer"): super().__init__(hs) self.pdu_destination_tried: 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 # Cache mapping `event_id` to a tuple of the event itself and the `pull_origin` # (which server we pulled the event from) self._get_pdu_cache: ExpiringCache[str, Tuple[EventBase, str]] = ExpiringCache( cache_name="get_pdu_cache", clock=self._clock, max_len=1000, expiry_ms=120 * 1000, reset_expiry_on_get=False, ) # A cache for fetching the room hierarchy over federation. # # Some stale data over federation is OK, but must be refreshed # periodically since the local server is in the room. # # It is a map of (room ID, suggested-only) -> the response of # get_room_hierarchy. self._get_room_hierarchy_cache: ExpiringCache[ Tuple[str, bool], Tuple[JsonDict, Sequence[JsonDict], Sequence[JsonDict], Sequence[str]], ] = ExpiringCache( cache_name="get_room_hierarchy_cache", clock=self._clock, max_len=1000, expiry_ms=5 * 60 * 1000, reset_expiry_on_get=False, ) def _clear_tried_cache(self) -> None: """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 async def make_query( self, destination: str, query_type: str, args: QueryParams, 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, ) 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 ) 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 ) async def claim_client_keys( self, destination: str, content: JsonDict, timeout: Optional[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 ) @trace @tag_args async def backfill( self, dest: str, room_id: str, limit: int, extremities: Collection[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 Must be a Collection that is falsy when empty. (Iterable is not enough here!) """ 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) if not isinstance(transaction_data, dict): # TODO we probably want an exception type specific to federation # client validation. raise TypeError("Backfill transaction_data is not a dict.") transaction_data_pdus = transaction_data.get("pdus") if not isinstance(transaction_data_pdus, list): # TODO we probably want an exception type specific to federation # client validation. raise TypeError("transaction_data.pdus is not a list.") room_version = await self.store.get_room_version(room_id) pdus = [event_from_pdu_json(p, room_version) 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_for_pulled_events_and_fetch( dest, pdus, room_version=room_version ) return pdus async def get_pdu_from_destination_raw( self, destination: str, event_id: str, room_version: RoomVersion, timeout: Optional[int] = None, ) -> Optional[EventBase]: """Requests the PDU with given origin and ID from the remote home server. Does not have any caching or rate limiting! Args: destination: Which homeserver to query event_id: event to fetch room_version: version of the room timeout: How long to try (in ms) each destination for before moving to the next destination. None indicates no timeout. Returns: A copy of the requested PDU that is safe to modify, or None if we were unable to find it. Raises: SynapseError, NotRetryingDestination, FederationDeniedError """ transaction_data = await self.transport_layer.get_event( destination, event_id, timeout=timeout ) logger.debug( "get_pdu_from_destination_raw: retrieved event id %s from %s: %r", event_id, destination, transaction_data, ) pdu_list: List[EventBase] = [ event_from_pdu_json(p, room_version) for p in transaction_data["pdus"] ] if pdu_list and pdu_list[0]: pdu = pdu_list[0] # Check signatures are correct. try: async def _record_failure_callback( event: EventBase, cause: str ) -> None: await self.store.record_event_failed_pull_attempt( event.room_id, event.event_id, cause ) signed_pdu = await self._check_sigs_and_hash( room_version, pdu, _record_failure_callback ) except InvalidEventSignatureError as e: errmsg = f"event id {pdu.event_id}: {e}" logger.warning("%s", errmsg) raise SynapseError(403, errmsg, Codes.FORBIDDEN) return signed_pdu return None @trace @tag_args async def get_pdu( self, destinations: Collection[str], event_id: str, room_version: RoomVersion, timeout: Optional[int] = None, ) -> Optional[PulledPduInfo]: """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 timeout: How long to try (in ms) each destination for before moving to the next destination. None indicates no timeout. Returns: The requested PDU wrapped in `PulledPduInfo`, or None if we were unable to find it. """ logger.debug( "get_pdu(event_id=%s): from destinations=%s", event_id, destinations ) # TODO: Rate limit the number of times we try and get the same event. # We might need the same event multiple times in quick succession (before # it gets persisted to the database), so we cache the results of the lookup. # Note that this is separate to the regular get_event cache which caches # events once they have been persisted. get_pdu_cache_entry = self._get_pdu_cache.get(event_id) event = None pull_origin = None if get_pdu_cache_entry: event, pull_origin = get_pdu_cache_entry # If we don't see the event in the cache, go try to fetch it from the # provided remote federated destinations else: pdu_attempts = self.pdu_destination_tried.setdefault(event_id, {}) # TODO: We can probably refactor this to use `_try_destination_list` for destination in destinations: now = self._clock.time_msec() last_attempt = pdu_attempts.get(destination, 0) if last_attempt + PDU_RETRY_TIME_MS > now: logger.debug( "get_pdu(event_id=%s): skipping destination=%s because we tried it recently last_attempt=%s and we only check every %s (now=%s)", event_id, destination, last_attempt, PDU_RETRY_TIME_MS, now, ) continue try: event = await self.get_pdu_from_destination_raw( destination=destination, event_id=event_id, room_version=room_version, timeout=timeout, ) pull_origin = destination pdu_attempts[destination] = now if event: # Prime the cache self._get_pdu_cache[event.event_id] = (event, pull_origin) # Now that we have an event, we can break out of this # loop and stop asking other destinations. break except NotRetryingDestination as e: logger.info("get_pdu(event_id=%s): %s", event_id, e) continue except FederationDeniedError: logger.info( "get_pdu(event_id=%s): Not attempting to fetch PDU from %s because the homeserver is not on our federation whitelist", event_id, destination, ) continue except SynapseError as e: logger.info( "get_pdu(event_id=%s): Failed to get PDU from %s because %s", event_id, destination, e, ) continue except Exception as e: pdu_attempts[destination] = now logger.info( "get_pdu(event_id=%s): Failed to get PDU from %s because %s", event_id, destination, e, ) continue if not event or not pull_origin: return None # `event` now refers to an object stored in `get_pdu_cache`. Our # callers may need to modify the returned object (eg to set # `event.internal_metadata.outlier = true`), so we return a copy # rather than the original object. event_copy = make_event_from_dict( event.get_pdu_json(), event.room_version, ) return PulledPduInfo(event_copy, pull_origin) @trace @tag_args 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) Raises: InvalidResponseError: if fields in the response have the wrong type. """ 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", []) set_tag( SynapseTags.RESULT_PREFIX + "state_event_ids", str(state_event_ids), ) set_tag( SynapseTags.RESULT_PREFIX + "state_event_ids.length", str(len(state_event_ids)), ) set_tag( SynapseTags.RESULT_PREFIX + "auth_event_ids", str(auth_event_ids), ) set_tag( SynapseTags.RESULT_PREFIX + "auth_event_ids.length", str(len(auth_event_ids)), ) if not isinstance(state_event_ids, list) or not isinstance( auth_event_ids, list ): raise InvalidResponseError("invalid response from /state_ids") return state_event_ids, auth_event_ids @trace @tag_args async def get_room_state( self, destination: str, room_id: str, event_id: str, room_version: RoomVersion, ) -> Tuple[List[EventBase], List[EventBase]]: """Calls the /state endpoint to fetch the state at a particular point in the room. Any invalid events (those with incorrect or unverifiable signatures or hashes) are filtered out from the response, and any duplicate events are removed. (Size limits and other event-format checks are *not* performed.) Note that the result is not ordered, so callers must be careful to process the events in an order that handles dependencies. Returns: a tuple of (state events, auth events) """ result = await self.transport_layer.get_room_state( room_version, destination, room_id, event_id, ) state_events = result.state auth_events = result.auth_events # we may as well filter out any duplicates from the response, to save # processing them multiple times. (In particular, events may be present in # `auth_events` as well as `state`, which is redundant). # # We don't rely on the sort order of the events, so we can just stick them # in a dict. state_event_map = {event.event_id: event for event in state_events} auth_event_map = { event.event_id: event for event in auth_events if event.event_id not in state_event_map } logger.info( "Processing from /state: %d state events, %d auth events", len(state_event_map), len(auth_event_map), ) valid_auth_events = await self._check_sigs_and_hash_for_pulled_events_and_fetch( destination, auth_event_map.values(), room_version ) valid_state_events = ( await self._check_sigs_and_hash_for_pulled_events_and_fetch( destination, state_event_map.values(), room_version ) ) return valid_state_events, valid_auth_events @trace async def _check_sigs_and_hash_for_pulled_events_and_fetch( self, origin: str, pdus: Collection[EventBase], room_version: RoomVersion, ) -> List[EventBase]: """ Checks the signatures and hashes of a list of pulled events we got from federation and records any signature failures as failed pull attempts. If a PDU fails its signature check then we check if we have it in the database, and if not then request it from the sender's server (if that is different from `origin`). If that still fails, the event is omitted from the returned list. If a PDU fails its content hash check then it is redacted. Also runs each event through the spam checker; if it fails, redacts the event and flags it as soft-failed. The given list of PDUs are not modified; instead the function returns a new list. Args: origin: The server that sent us these events pdus: The events to be checked room_version: the version of the room these events are in Returns: A list of PDUs that have valid signatures and hashes. """ set_tag( SynapseTags.RESULT_PREFIX + "pdus.length", str(len(pdus)), ) # We limit how many PDUs we check at once, as if we try to do hundreds # of thousands of PDUs at once we see large memory spikes. valid_pdus: List[EventBase] = [] async def _record_failure_callback(event: EventBase, cause: str) -> None: await self.store.record_event_failed_pull_attempt( event.room_id, event.event_id, cause ) async def _execute(pdu: EventBase) -> None: valid_pdu = await self._check_sigs_and_hash_and_fetch_one( pdu=pdu, origin=origin, room_version=room_version, record_failure_callback=_record_failure_callback, ) if valid_pdu: valid_pdus.append(valid_pdu) await concurrently_execute(_execute, pdus, 10000) return valid_pdus @trace @tag_args async def _check_sigs_and_hash_and_fetch_one( self, pdu: EventBase, origin: str, room_version: RoomVersion, record_failure_callback: Optional[ Callable[[EventBase, str], Awaitable[None]] ] = None, ) -> Optional[EventBase]: """Takes a PDU and checks its signatures and hashes. If the PDU fails its signature check then we check if we have it in the database; if not, we then request it from sender's server (if that is not the same as `origin`). If that still fails, we return None. If the PDU fails its content hash check, it is redacted. Also runs the event through the spam checker; if it fails, redacts the event and flags it as soft-failed. Args: origin pdu room_version record_failure_callback: A callback to run whenever the given event fails signature or hash checks. This includes exceptions that would be normally be thrown/raised but also things like checking for event tampering where we just return the redacted event. Returns: The PDU (possibly redacted) if it has valid signatures and hashes. None if no valid copy could be found. """ try: return await self._check_sigs_and_hash( room_version, pdu, record_failure_callback ) except InvalidEventSignatureError as e: logger.warning( "Signature on retrieved event %s was invalid (%s). " "Checking local store/origin server", pdu.event_id, e, ) log_kv( { "message": "Signature on retrieved event was invalid. " "Checking local store/origin server", "event_id": pdu.event_id, "InvalidEventSignatureError": e, } ) # Check local db. res = await self.store.get_event( pdu.event_id, allow_rejected=True, allow_none=True ) # If the PDU fails its signature check and we don't have it in our # database, we then request it from sender's server (if that is not the # same as `origin`). pdu_origin = get_domain_from_id(pdu.sender) if not res and pdu_origin != origin: try: pulled_pdu_info = await self.get_pdu( destinations=[pdu_origin], event_id=pdu.event_id, room_version=room_version, timeout=10000, ) if pulled_pdu_info is not None: res = pulled_pdu_info.pdu except SynapseError: pass if not res: logger.warning( "Failed to find copy of %s with valid signature", pdu.event_id ) return res 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) for p in res["auth_chain"]] signed_auth = await self._check_sigs_and_hash_for_pulled_events_and_fetch( destination, auth_chain, room_version=room_version ) return signed_auth def _is_unknown_endpoint( self, e: HttpResponseException, synapse_error: Optional[SynapseError] = None ) -> bool: """ Returns true if the response was due to an endpoint being unimplemented. Args: e: The error response received from the remote server. synapse_error: The above error converted to a SynapseError. This is automatically generated if not provided. """ if synapse_error is None: synapse_error = e.to_synapse_error() # There is no good way to detect an "unknown" endpoint. # # Dendrite returns a 404 (with a body of "404 page not found"); # Conduit returns a 404 (with no body); and Synapse returns a 400 # with M_UNRECOGNIZED. # # This needs to be rather specific as some endpoints truly do return 404 # errors. return ( e.code == 404 and (not e.response or e.response == b"404 page not found") ) or (e.code == 400 and synapse_error.errcode == Codes.UNRECOGNIZED) async def _try_destination_list( self, description: str, destinations: Iterable[str], callback: Callable[[str], Awaitable[T]], failover_errcodes: Optional[Container[str]] = None, 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 or an UnsupportedRoomVersionError, 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_errcodes: Error codes (specific to this endpoint) which should cause a failover when received as part of an HTTP 400 error. 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. """ if failover_errcodes is None: failover_errcodes = () if not destinations: # Give a bit of a clearer message if no servers were specified at all. raise SynapseError( 502, f"Failed to {description} via any server: No servers specified." ) for destination in destinations: # We don't want to ask our own server for information we don't have if destination == self.server_name: continue try: return await callback(destination) except ( RequestSendFailed, InvalidResponseError, ) as e: logger.warning("Failed to %s via %s: %s", description, destination, e) # Skip to the next homeserver in the list to try. continue except NotRetryingDestination as e: logger.info("%s: %s", description, e) continue except FederationDeniedError: logger.info( "%s: Not attempting to %s from %s because the homeserver is not on our federation whitelist", description, description, destination, ) continue except UnsupportedRoomVersionError: raise except HttpResponseException as e: synapse_error = e.to_synapse_error() failover = False # Failover should occur: # # * On internal server errors. # * If the destination responds that it cannot complete the request. # * If the destination doesn't implemented the endpoint for some reason. if 500 <= e.code < 600: failover = True elif e.code == 400 and synapse_error.errcode in failover_errcodes: failover = True elif failover_on_unknown_endpoint and self._is_unknown_endpoint( e, synapse_error ): 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, f"Failed to {description} via any server") 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, or no servers successfully handle the request. """ valid_memberships = {Membership.JOIN, Membership.LEAVE, Membership.KNOCK} 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() if not room_version.msc2403_knocking and membership == Membership.KNOCK: raise SynapseError( 400, "This room version does not support knocking", errcode=Codes.FORBIDDEN, ) 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 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 # MSC3083 defines additional error codes for room joins. Unfortunately # we do not yet know the room version, assume these will only be returned # by valid room versions. failover_errcodes = ( (Codes.UNABLE_AUTHORISE_JOIN, Codes.UNABLE_TO_GRANT_JOIN) if membership == Membership.JOIN else None ) return await self._try_destination_list( "make_" + membership, destinations, send_request, failover_errcodes=failover_errcodes, ) async def send_join( self, destinations: Iterable[str], pdu: EventBase, room_version: RoomVersion ) -> SendJoinResult: """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: The result of the send join request. Raises: SynapseError: if the chosen remote server returns a 300/400 code, or no servers successfully handle the request. """ async def send_request(destination: str) -> SendJoinResult: response = await self._do_send_join(room_version, destination, pdu) # If an event was returned (and expected to be returned): # # * Ensure it has the same event ID (note that the event ID is a hash # of the event fields for versions which support MSC3083). # * Ensure the signatures are good. # # Otherwise, fallback to the provided event. if room_version.msc3083_join_rules and response.event: event = response.event valid_pdu = await self._check_sigs_and_hash_and_fetch_one( pdu=event, origin=destination, room_version=room_version, ) if valid_pdu is None or event.event_id != pdu.event_id: raise InvalidResponseError("Returned an invalid join event") else: event = pdu state = response.state auth_chain = response.auth_events 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 InvalidResponseError("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,) ) logger.info( "Processing from send_join %d events", len(state) + len(auth_chain) ) # We now go and check the signatures and hashes for the event. Note # that we limit how many events we process at a time to keep the # memory overhead from exploding. valid_pdus_map: Dict[str, EventBase] = {} async def _execute(pdu: EventBase) -> None: valid_pdu = await self._check_sigs_and_hash_and_fetch_one( pdu=pdu, origin=destination, room_version=room_version, ) if valid_pdu: valid_pdus_map[valid_pdu.event_id] = valid_pdu await concurrently_execute( _execute, itertools.chain(state, auth_chain), 10000 ) # 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 auth chain doesn't include a different create event 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 and auth_chain_create_events != [ create_event.event_id ]: raise InvalidResponseError( "Unexpected create event(s) in auth chain: %s" % (auth_chain_create_events,) ) if response.partial_state and not response.servers_in_room: raise InvalidResponseError( "partial_state was set, but no servers were listed in the room" ) return SendJoinResult( event=event, state=signed_state, auth_chain=signed_auth, origin=destination, partial_state=response.partial_state, servers_in_room=response.servers_in_room or [], ) # MSC3083 defines additional error codes for room joins. failover_errcodes = None if room_version.msc3083_join_rules: failover_errcodes = ( Codes.UNABLE_AUTHORISE_JOIN, Codes.UNABLE_TO_GRANT_JOIN, ) # If the join is being authorised via allow rules, we need to send # the /send_join back to the same server that was originally used # with /make_join. if EventContentFields.AUTHORISING_USER in pdu.content: destinations = [ get_domain_from_id(pdu.content[EventContentFields.AUTHORISING_USER]) ] return await self._try_destination_list( "send_join", destinations, send_request, failover_errcodes=failover_errcodes ) async def _do_send_join( self, room_version: RoomVersion, destination: str, pdu: EventBase ) -> SendJoinResponse: time_now = self._clock.time_msec() try: return await self.transport_layer.send_join_v2( room_version=room_version, destination=destination, room_id=pdu.room_id, event_id=pdu.event_id, content=pdu.get_pdu_json(time_now), ) except HttpResponseException as e: # If an error is received that is due to an unrecognised endpoint, # fallback to the v1 endpoint. Otherwise, consider it a legitimate error # and raise. if not self._is_unknown_endpoint(e): raise logger.debug("Couldn't send_join with the v2 API, falling back to the v1 API") return await self.transport_layer.send_join_v1( room_version=room_version, destination=destination, room_id=pdu.room_id, event_id=pdu.event_id, content=pdu.get_pdu_json(time_now), ) 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. try: pdu = await self._check_sigs_and_hash(room_version, pdu) except InvalidEventSignatureError as e: errmsg = f"event id {pdu.event_id}: {e}" logger.warning("%s", errmsg) raise SynapseError(403, errmsg, Codes.FORBIDDEN) # 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 Raises: SynapseError: if the remote server returns an error or if the server only supports the v1 endpoint and a room version other than "1" or "2" is requested. """ 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 an error is received that is due to an unrecognised endpoint, # fallback to the v1 endpoint if the room uses old-style event IDs. # Otherwise, consider it a legitimate error and raise. err = e.to_synapse_error() if self._is_unknown_endpoint(e, err): if room_version.event_format != EventFormatVersions.ROOM_V1_V2: raise SynapseError( 400, "User's homeserver does not support this room version", Codes.UNSUPPORTED_ROOM_VERSION, ) else: raise err # 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, or no servers successfully handle the request. """ 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 an error is received that is due to an unrecognised endpoint, # fallback to the v1 endpoint. Otherwise, consider it a legitimate error # and raise. if not self._is_unknown_endpoint(e): raise 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 send_knock(self, destinations: List[str], pdu: EventBase) -> JsonDict: """Attempts to send a knock event to a given list of servers. Iterates through the list until one attempt succeeds. 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: A list of candidate homeservers which are likely to be participating in the room. pdu: The event to be sent. Returns: The remote homeserver return some state from the room. The response dictionary is in the form: {"knock_state_events": [, ...]} The list of state events may be empty. Raises: SynapseError: If the chosen remote server returns a 3xx/4xx code. RuntimeError: If no servers were reachable. """ async def send_request(destination: str) -> JsonDict: return await self._do_send_knock(destination, pdu) return await self._try_destination_list( "send_knock", destinations, send_request ) async def _do_send_knock(self, destination: str, pdu: EventBase) -> JsonDict: """Send a knock event to a remote homeserver. Args: destination: The homeserver to send to. pdu: The event to send. Returns: The remote homeserver can optionally return some state from the room. The response dictionary is in the form: {"knock_state_events": [, ...]} The list of state events may be empty. """ time_now = self._clock.time_msec() return await self.transport_layer.send_knock_v1( destination=destination, room_id=pdu.room_id, event_id=pdu.event_id, content=pdu.get_pdu_json(time_now), ) 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 / RequestSendFailed: 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_for_pulled_events_and_fetch( destination, events, 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_room_hierarchy( self, destinations: Iterable[str], room_id: str, suggested_only: bool, ) -> Tuple[JsonDict, Sequence[JsonDict], Sequence[JsonDict], Sequence[str]]: """ Call other servers to get a hierarchy of the given room. Performs simple data validates and parsing of the response. 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 Returns: A tuple of: The room as a JSON dictionary, without a "children_state" key. A list of `m.space.child` state events. A list of children rooms, as JSON dictionaries. A list of inaccessible children room IDs. Raises: SynapseError if we were unable to get a valid summary from any of the remote servers """ cached_result = self._get_room_hierarchy_cache.get((room_id, suggested_only)) if cached_result: return cached_result async def send_request( destination: str, ) -> Tuple[JsonDict, Sequence[JsonDict], Sequence[JsonDict], Sequence[str]]: try: res = await self.transport_layer.get_room_hierarchy( destination=destination, room_id=room_id, suggested_only=suggested_only, ) except HttpResponseException as e: # If an error is received that is due to an unrecognised endpoint, # fallback to the unstable endpoint. Otherwise, consider it a # legitimate error and raise. if not self._is_unknown_endpoint(e): raise logger.debug( "Couldn't fetch room hierarchy with the v1 API, falling back to the unstable API" ) res = await self.transport_layer.get_room_hierarchy_unstable( destination=destination, room_id=room_id, suggested_only=suggested_only, ) room = res.get("room") if not isinstance(room, dict): raise InvalidResponseError("'room' must be a dict") if room.get("room_id") != room_id: raise InvalidResponseError("wrong room returned in hierarchy response") # Validate children_state of the room. children_state = room.pop("children_state", []) if not isinstance(children_state, list): raise InvalidResponseError("'room.children_state' must be a list") if any(not isinstance(e, dict) for e in children_state): raise InvalidResponseError("Invalid event in 'children_state' list") try: for child_state in children_state: _validate_hierarchy_event(child_state) except ValueError as e: raise InvalidResponseError(str(e)) # Validate the children rooms. children = res.get("children", []) if not isinstance(children, list): raise InvalidResponseError("'children' must be a list") if any(not isinstance(r, dict) for r in children): raise InvalidResponseError("Invalid room in 'children' list") # Validate the inaccessible children. inaccessible_children = res.get("inaccessible_children", []) if not isinstance(inaccessible_children, list): raise InvalidResponseError("'inaccessible_children' must be a list") if any(not isinstance(r, str) for r in inaccessible_children): raise InvalidResponseError( "Invalid room ID in 'inaccessible_children' list" ) return room, children_state, children, inaccessible_children result = await self._try_destination_list( "fetch room hierarchy", destinations, send_request, failover_on_unknown_endpoint=True, ) # Cache the result to avoid fetching data over federation every time. self._get_room_hierarchy_cache[(room_id, suggested_only)] = result return result async def timestamp_to_event( self, *, destinations: List[str], room_id: str, timestamp: int, direction: str ) -> Optional["TimestampToEventResponse"]: """ Calls each remote federating server from `destinations` asking for their closest event to the given timestamp in the given direction until we get a response. Also validates the response to always return the expected keys or raises an error. Args: destinations: The domains of homeservers to try fetching from room_id: Room to fetch the event from timestamp: The point in time (inclusive) we should navigate from in the given direction to find the closest event. direction: ["f"|"b"] to indicate whether we should navigate forward or backward from the given timestamp to find the closest event. Returns: A parsed TimestampToEventResponse including the closest event_id and origin_server_ts or None if no destination has a response. """ async def _timestamp_to_event_from_destination( destination: str, ) -> TimestampToEventResponse: return await self._timestamp_to_event_from_destination( destination, room_id, timestamp, direction ) try: # Loop through each homeserver candidate until we get a succesful response timestamp_to_event_response = await self._try_destination_list( "timestamp_to_event", destinations, # TODO: The requested timestamp may lie in a part of the # event graph that the remote server *also* didn't have, # in which case they will have returned another event # which may be nowhere near the requested timestamp. In # the future, we may need to reconcile that gap and ask # other homeservers, and/or extend `/timestamp_to_event` # to return events on *both* sides of the timestamp to # help reconcile the gap faster. _timestamp_to_event_from_destination, ) return timestamp_to_event_response except SynapseError: return None async def _timestamp_to_event_from_destination( self, destination: str, room_id: str, timestamp: int, direction: str ) -> "TimestampToEventResponse": """ Calls a remote federating server at `destination` asking for their closest event to the given timestamp in the given direction. Also validates the response to always return the expected keys or raises an error. Args: destination: Domain name of the remote homeserver room_id: Room to fetch the event from timestamp: The point in time (inclusive) we should navigate from in the given direction to find the closest event. direction: ["f"|"b"] to indicate whether we should navigate forward or backward from the given timestamp to find the closest event. Returns: A parsed TimestampToEventResponse including the closest event_id and origin_server_ts Raises: Various exceptions when the request fails InvalidResponseError when the response does not have the correct keys or wrong types """ remote_response = await self.transport_layer.timestamp_to_event( destination, room_id, timestamp, direction ) if not isinstance(remote_response, dict): raise InvalidResponseError( "Response must be a JSON dictionary but received %r" % remote_response ) try: return TimestampToEventResponse.from_json_dict(remote_response) except ValueError as e: raise InvalidResponseError(str(e)) async def get_account_status( self, destination: str, user_ids: List[str] ) -> Tuple[JsonDict, List[str]]: """Retrieves account statuses for a given list of users on a given remote homeserver. If the request fails for any reason, all user IDs for this destination are marked as failed. Args: destination: the destination to contact user_ids: the user ID(s) for which to request account status(es) Returns: The account statuses, as well as the list of user IDs for which it was not possible to retrieve a status. """ try: res = await self.transport_layer.get_account_status(destination, user_ids) except Exception: # If the query failed for any reason, mark all the users as failed. return {}, user_ids statuses = res.get("account_statuses", {}) failures = res.get("failures", []) if not isinstance(statuses, dict) or not isinstance(failures, list): # Make sure we're not feeding back malformed data back to the caller. logger.warning( "Destination %s responded with malformed data to account_status query", destination, ) return {}, user_ids for user_id in user_ids: # Any account whose status is missing is a user we failed to receive the # status of. if user_id not in statuses and user_id not in failures: failures.append(user_id) # Filter out any user ID that doesn't belong to the remote server that sent its # status (or failure). def filter_user_id(user_id: str) -> bool: try: return UserID.from_string(user_id).domain == destination except SynapseError: # If the user ID doesn't parse, ignore it. return False filtered_statuses = dict( # item is a (key, value) tuple, so item[0] is the user ID. filter(lambda item: filter_user_id(item[0]), statuses.items()) ) filtered_failures = list(filter(filter_user_id, failures)) return filtered_statuses, filtered_failures @attr.s(frozen=True, slots=True, auto_attribs=True) class TimestampToEventResponse: """Typed response dictionary for the federation /timestamp_to_event endpoint""" event_id: str origin_server_ts: int # the raw data, including the above keys data: JsonDict @classmethod def from_json_dict(cls, d: JsonDict) -> "TimestampToEventResponse": """Parsed response from the federation /timestamp_to_event endpoint Args: d: JSON object response to be parsed Raises: ValueError if d does not the correct keys or they are the wrong types """ event_id = d.get("event_id") if not isinstance(event_id, str): raise ValueError( "Invalid response: 'event_id' must be a str but received %r" % event_id ) origin_server_ts = d.get("origin_server_ts") if not isinstance(origin_server_ts, int): raise ValueError( "Invalid response: 'origin_server_ts' must be a int but received %r" % origin_server_ts ) return cls(event_id, origin_server_ts, d) def _validate_hierarchy_event(d: JsonDict) -> None: """Validate an event within the result of a /hierarchy 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, list): 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")