diff options
Diffstat (limited to 'synapse/federation/federation_server.py')
| -rw-r--r-- | synapse/federation/federation_server.py | 567 |
1 files changed, 394 insertions, 173 deletions
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py index 51e3fdea06..e501251b6e 100644 --- a/synapse/federation/federation_server.py +++ b/synapse/federation/federation_server.py @@ -1,5 +1,6 @@ # -*- coding: utf-8 -*- # Copyright 2015, 2016 OpenMarket Ltd +# Copyright 2018 New Vector Ltd # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. @@ -12,92 +13,72 @@ # 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 +import re +import six +from six import iteritems -from twisted.internet import defer - -from .federation_base import FederationBase -from .units import Transaction, Edu - -from synapse.util.async import Linearizer -from synapse.util.logutils import log_function -from synapse.util.caches.response_cache import ResponseCache -from synapse.events import FrozenEvent -from synapse.types import get_domain_from_id -import synapse.metrics +from canonicaljson import json +from prometheus_client import Counter -from synapse.api.errors import AuthError, FederationError, SynapseError +from twisted.internet import defer +from twisted.internet.abstract import isIPAddress +from twisted.python import failure +from synapse.api.constants import EventTypes +from synapse.api.errors import AuthError, FederationError, NotFoundError, SynapseError from synapse.crypto.event_signing import compute_event_signature +from synapse.federation.federation_base import FederationBase, event_from_pdu_json +from synapse.federation.persistence import TransactionActions +from synapse.federation.units import Edu, Transaction +from synapse.http.endpoint import parse_server_name +from synapse.types import get_domain_from_id +from synapse.util import async +from synapse.util.caches.response_cache import ResponseCache +from synapse.util.logutils import log_function -import simplejson as json -import logging - +# when processing incoming transactions, we try to handle multiple rooms in +# parallel, up to this limit. +TRANSACTION_CONCURRENCY_LIMIT = 10 logger = logging.getLogger(__name__) -# synapse.federation.federation_server is a silly name -metrics = synapse.metrics.get_metrics_for("synapse.federation.server") - -received_pdus_counter = metrics.register_counter("received_pdus") +received_pdus_counter = Counter("synapse_federation_server_received_pdus", "") -received_edus_counter = metrics.register_counter("received_edus") +received_edus_counter = Counter("synapse_federation_server_received_edus", "") -received_queries_counter = metrics.register_counter("received_queries", labels=["type"]) +received_queries_counter = Counter( + "synapse_federation_server_received_queries", "", ["type"] +) class FederationServer(FederationBase): + def __init__(self, hs): super(FederationServer, self).__init__(hs) self.auth = hs.get_auth() + self.handler = hs.get_handlers().federation_handler - self._server_linearizer = Linearizer("fed_server") + self._server_linearizer = async.Linearizer("fed_server") + self._transaction_linearizer = async.Linearizer("fed_txn_handler") - # We cache responses to state queries, as they take a while and often - # come in waves. - self._state_resp_cache = ResponseCache(hs, timeout_ms=30000) + self.transaction_actions = TransactionActions(self.store) - def set_handler(self, handler): - """Sets the handler that the replication layer will use to communicate - receipt of new PDUs from other home servers. The required methods are - documented on :py:class:`.ReplicationHandler`. - """ - self.handler = handler + self.registry = hs.get_federation_registry() - def register_edu_handler(self, edu_type, handler): - if edu_type in self.edu_handlers: - raise KeyError("Already have an EDU handler for %s" % (edu_type,)) - - self.edu_handlers[edu_type] = handler - - def register_query_handler(self, query_type, handler): - """Sets the handler callable that will be used to handle an incoming - federation Query of the given type. - - Args: - query_type (str): Category name of the query, which should match - the string used by make_query. - handler (callable): Invoked to handle incoming queries of this type - - handler is invoked as: - result = handler(args) - - where 'args' is a dict mapping strings to strings of the query - arguments. It should return a Deferred that will eventually yield an - object to encode as JSON. - """ - if query_type in self.query_handlers: - raise KeyError( - "Already have a Query handler for %s" % (query_type,) - ) - - self.query_handlers[query_type] = handler + # We cache responses to state queries, as they take a while and often + # come in waves. + self._state_resp_cache = ResponseCache(hs, "state_resp", timeout_ms=30000) @defer.inlineCallbacks @log_function def on_backfill_request(self, origin, room_id, versions, limit): with (yield self._server_linearizer.queue((origin, room_id))): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + pdus = yield self.handler.on_backfill_request( origin, room_id, versions, limit ) @@ -109,25 +90,41 @@ class FederationServer(FederationBase): @defer.inlineCallbacks @log_function def on_incoming_transaction(self, transaction_data): + # keep this as early as possible to make the calculated origin ts as + # accurate as possible. + request_time = self._clock.time_msec() + transaction = Transaction(**transaction_data) - received_pdus_counter.inc_by(len(transaction.pdus)) + if not transaction.transaction_id: + raise Exception("Transaction missing transaction_id") + if not transaction.origin: + raise Exception("Transaction missing origin") - for p in transaction.pdus: - if "unsigned" in p: - unsigned = p["unsigned"] - if "age" in unsigned: - p["age"] = unsigned["age"] - if "age" in p: - p["age_ts"] = int(self._clock.time_msec()) - int(p["age"]) - del p["age"] + logger.debug("[%s] Got transaction", transaction.transaction_id) - pdu_list = [ - self.event_from_pdu_json(p) for p in transaction.pdus - ] + # use a linearizer to ensure that we don't process the same transaction + # multiple times in parallel. + with (yield self._transaction_linearizer.queue( + (transaction.origin, transaction.transaction_id), + )): + result = yield self._handle_incoming_transaction( + transaction, request_time, + ) - logger.debug("[%s] Got transaction", transaction.transaction_id) + defer.returnValue(result) + + @defer.inlineCallbacks + def _handle_incoming_transaction(self, transaction, request_time): + """ Process an incoming transaction and return the HTTP response + + Args: + transaction (Transaction): incoming transaction + request_time (int): timestamp that the HTTP request arrived at + Returns: + Deferred[(int, object)]: http response code and body + """ response = yield self.transaction_actions.have_responded(transaction) if response: @@ -140,42 +137,67 @@ class FederationServer(FederationBase): logger.debug("[%s] Transaction is new", transaction.transaction_id) - results = [] - - for pdu in pdu_list: - # check that it's actually being sent from a valid destination to - # workaround bug #1753 in 0.18.5 and 0.18.6 - if transaction.origin != get_domain_from_id(pdu.event_id): - # We continue to accept join events from any server; this is - # necessary for the federation join dance to work correctly. - # (When we join over federation, the "helper" server is - # responsible for sending out the join event, rather than the - # origin. See bug #1893). - if not ( - pdu.type == 'm.room.member' and - pdu.content and - pdu.content.get("membership", None) == 'join' - ): - logger.info( - "Discarding PDU %s from invalid origin %s", - pdu.event_id, transaction.origin + received_pdus_counter.inc(len(transaction.pdus)) + + origin_host, _ = parse_server_name(transaction.origin) + + pdus_by_room = {} + + for p in transaction.pdus: + if "unsigned" in p: + unsigned = p["unsigned"] + if "age" in unsigned: + p["age"] = unsigned["age"] + if "age" in p: + p["age_ts"] = request_time - int(p["age"]) + del p["age"] + + event = event_from_pdu_json(p) + room_id = event.room_id + pdus_by_room.setdefault(room_id, []).append(event) + + pdu_results = {} + + # we can process different rooms in parallel (which is useful if they + # require callouts to other servers to fetch missing events), but + # impose a limit to avoid going too crazy with ram/cpu. + + @defer.inlineCallbacks + def process_pdus_for_room(room_id): + logger.debug("Processing PDUs for %s", room_id) + try: + yield self.check_server_matches_acl(origin_host, room_id) + except AuthError as e: + logger.warn( + "Ignoring PDUs for room %s from banned server", room_id, + ) + for pdu in pdus_by_room[room_id]: + event_id = pdu.event_id + pdu_results[event_id] = e.error_dict() + return + + for pdu in pdus_by_room[room_id]: + event_id = pdu.event_id + try: + yield self._handle_received_pdu( + transaction.origin, pdu ) - continue - else: - logger.info( - "Accepting join PDU %s from %s", - pdu.event_id, transaction.origin + pdu_results[event_id] = {} + except FederationError as e: + logger.warn("Error handling PDU %s: %s", event_id, e) + pdu_results[event_id] = {"error": str(e)} + except Exception as e: + f = failure.Failure() + pdu_results[event_id] = {"error": str(e)} + logger.error( + "Failed to handle PDU %s: %s", + event_id, f.getTraceback().rstrip(), ) - try: - yield self._handle_received_pdu(transaction.origin, pdu) - results.append({}) - except FederationError as e: - self.send_failure(e, transaction.origin) - results.append({"error": str(e)}) - except Exception as e: - results.append({"error": str(e)}) - logger.exception("Failed to handle PDU") + yield async.concurrently_execute( + process_pdus_for_room, pdus_by_room.keys(), + TRANSACTION_CONCURRENCY_LIMIT, + ) if hasattr(transaction, "edus"): for edu in (Edu(**x) for x in transaction.edus): @@ -185,17 +207,16 @@ class FederationServer(FederationBase): edu.content ) - for failure in getattr(transaction, "pdu_failures", []): - logger.info("Got failure %r", failure) - - logger.debug("Returning: %s", str(results)) + pdu_failures = getattr(transaction, "pdu_failures", []) + for fail in pdu_failures: + logger.info("Got failure %r", fail) response = { - "pdus": dict(zip( - (p.event_id for p in pdu_list), results - )), + "pdus": pdu_results, } + logger.debug("Returning: %s", str(response)) + yield self.transaction_actions.set_response( transaction, 200, response @@ -205,16 +226,7 @@ class FederationServer(FederationBase): @defer.inlineCallbacks def received_edu(self, origin, edu_type, content): received_edus_counter.inc() - - if edu_type in self.edu_handlers: - try: - yield self.edu_handlers[edu_type](origin, content) - except SynapseError as e: - logger.info("Failed to handle edu %r: %r", edu_type, e) - except Exception as e: - logger.exception("Failed to handle edu %r", edu_type) - else: - logger.warn("Received EDU of type %s with no handler", edu_type) + yield self.registry.on_edu(edu_type, origin, content) @defer.inlineCallbacks @log_function @@ -222,19 +234,24 @@ class FederationServer(FederationBase): if not event_id: raise NotImplementedError("Specify an event") + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + in_room = yield self.auth.check_host_in_room(room_id, origin) if not in_room: raise AuthError(403, "Host not in room.") - result = self._state_resp_cache.get((room_id, event_id)) - if not result: - with (yield self._server_linearizer.queue((origin, room_id))): - resp = yield self._state_resp_cache.set( - (room_id, event_id), - self._on_context_state_request_compute(room_id, event_id) - ) - else: - resp = yield result + # we grab the linearizer to protect ourselves from servers which hammer + # us. In theory we might already have the response to this query + # in the cache so we could return it without waiting for the linearizer + # - but that's non-trivial to get right, and anyway somewhat defeats + # the point of the linearizer. + with (yield self._server_linearizer.queue((origin, room_id))): + resp = yield self._state_resp_cache.wrap( + (room_id, event_id), + self._on_context_state_request_compute, + room_id, event_id, + ) defer.returnValue((200, resp)) @@ -243,6 +260,9 @@ class FederationServer(FederationBase): if not event_id: raise NotImplementedError("Specify an event") + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + in_room = yield self.auth.check_host_in_room(room_id, origin) if not in_room: raise AuthError(403, "Host not in room.") @@ -286,7 +306,7 @@ class FederationServer(FederationBase): @defer.inlineCallbacks @log_function def on_pdu_request(self, origin, event_id): - pdu = yield self._get_persisted_pdu(origin, event_id) + pdu = yield self.handler.get_persisted_pdu(origin, event_id) if pdu: defer.returnValue( @@ -302,25 +322,23 @@ class FederationServer(FederationBase): @defer.inlineCallbacks def on_query_request(self, query_type, args): - received_queries_counter.inc(query_type) - - if query_type in self.query_handlers: - response = yield self.query_handlers[query_type](args) - defer.returnValue((200, response)) - else: - defer.returnValue( - (404, "No handler for Query type '%s'" % (query_type,)) - ) + received_queries_counter.labels(query_type).inc() + resp = yield self.registry.on_query(query_type, args) + defer.returnValue((200, resp)) @defer.inlineCallbacks - def on_make_join_request(self, room_id, user_id): + def on_make_join_request(self, origin, room_id, user_id): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) pdu = yield self.handler.on_make_join_request(room_id, user_id) time_now = self._clock.time_msec() defer.returnValue({"event": pdu.get_pdu_json(time_now)}) @defer.inlineCallbacks def on_invite_request(self, origin, content): - pdu = self.event_from_pdu_json(content) + pdu = event_from_pdu_json(content) + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, pdu.room_id) ret_pdu = yield self.handler.on_invite_request(origin, pdu) time_now = self._clock.time_msec() defer.returnValue((200, {"event": ret_pdu.get_pdu_json(time_now)})) @@ -328,7 +346,11 @@ class FederationServer(FederationBase): @defer.inlineCallbacks def on_send_join_request(self, origin, content): logger.debug("on_send_join_request: content: %s", content) - pdu = self.event_from_pdu_json(content) + pdu = event_from_pdu_json(content) + + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, pdu.room_id) + logger.debug("on_send_join_request: pdu sigs: %s", pdu.signatures) res_pdus = yield self.handler.on_send_join_request(origin, pdu) time_now = self._clock.time_msec() @@ -340,7 +362,9 @@ class FederationServer(FederationBase): })) @defer.inlineCallbacks - def on_make_leave_request(self, room_id, user_id): + def on_make_leave_request(self, origin, room_id, user_id): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) pdu = yield self.handler.on_make_leave_request(room_id, user_id) time_now = self._clock.time_msec() defer.returnValue({"event": pdu.get_pdu_json(time_now)}) @@ -348,7 +372,11 @@ class FederationServer(FederationBase): @defer.inlineCallbacks def on_send_leave_request(self, origin, content): logger.debug("on_send_leave_request: content: %s", content) - pdu = self.event_from_pdu_json(content) + pdu = event_from_pdu_json(content) + + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, pdu.room_id) + logger.debug("on_send_leave_request: pdu sigs: %s", pdu.signatures) yield self.handler.on_send_leave_request(origin, pdu) defer.returnValue((200, {})) @@ -356,6 +384,9 @@ class FederationServer(FederationBase): @defer.inlineCallbacks def on_event_auth(self, origin, room_id, event_id): with (yield self._server_linearizer.queue((origin, room_id))): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + time_now = self._clock.time_msec() auth_pdus = yield self.handler.on_event_auth(event_id) res = { @@ -384,8 +415,11 @@ class FederationServer(FederationBase): Deferred: Results in `dict` with the same format as `content` """ with (yield self._server_linearizer.queue((origin, room_id))): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + auth_chain = [ - self.event_from_pdu_json(e) + event_from_pdu_json(e) for e in content["auth_chain"] ] @@ -444,9 +478,9 @@ class FederationServer(FederationBase): "Claimed one-time-keys: %s", ",".join(( "%s for %s:%s" % (key_id, user_id, device_id) - for user_id, user_keys in json_result.iteritems() - for device_id, device_keys in user_keys.iteritems() - for key_id, _ in device_keys.iteritems() + for user_id, user_keys in iteritems(json_result) + for device_id, device_keys in iteritems(user_keys) + for key_id, _ in iteritems(device_keys) )), ) @@ -457,6 +491,9 @@ class FederationServer(FederationBase): def on_get_missing_events(self, origin, room_id, earliest_events, latest_events, limit, min_depth): with (yield self._server_linearizer.queue((origin, room_id))): + origin_host, _ = parse_server_name(origin) + yield self.check_server_matches_acl(origin_host, room_id) + logger.info( "on_get_missing_events: earliest_events: %r, latest_events: %r," " limit: %d, min_depth: %d", @@ -485,17 +522,6 @@ class FederationServer(FederationBase): ts_now_ms = self._clock.time_msec() return self.store.get_user_id_for_open_id_token(token, ts_now_ms) - @log_function - def _get_persisted_pdu(self, origin, event_id, do_auth=True): - """ Get a PDU from the database with given origin and id. - - Returns: - Deferred: Results in a `Pdu`. - """ - return self.handler.get_persisted_pdu( - origin, event_id, do_auth=do_auth - ) - def _transaction_from_pdus(self, pdu_list): """Returns a new Transaction containing the given PDUs suitable for transmission. @@ -513,13 +539,57 @@ class FederationServer(FederationBase): def _handle_received_pdu(self, origin, pdu): """ Process a PDU received in a federation /send/ transaction. + If the event is invalid, then this method throws a FederationError. + (The error will then be logged and sent back to the sender (which + probably won't do anything with it), and other events in the + transaction will be processed as normal). + + It is likely that we'll then receive other events which refer to + this rejected_event in their prev_events, etc. When that happens, + we'll attempt to fetch the rejected event again, which will presumably + fail, so those second-generation events will also get rejected. + + Eventually, we get to the point where there are more than 10 events + between any new events and the original rejected event. Since we + only try to backfill 10 events deep on received pdu, we then accept the + new event, possibly introducing a discontinuity in the DAG, with new + forward extremities, so normal service is approximately returned, + until we try to backfill across the discontinuity. + Args: origin (str): server which sent the pdu pdu (FrozenEvent): received pdu Returns (Deferred): completes with None - Raises: FederationError if the signatures / hash do not match - """ + + Raises: FederationError if the signatures / hash do not match, or + if the event was unacceptable for any other reason (eg, too large, + too many prev_events, couldn't find the prev_events) + """ + # check that it's actually being sent from a valid destination to + # workaround bug #1753 in 0.18.5 and 0.18.6 + if origin != get_domain_from_id(pdu.event_id): + # We continue to accept join events from any server; this is + # necessary for the federation join dance to work correctly. + # (When we join over federation, the "helper" server is + # responsible for sending out the join event, rather than the + # origin. See bug #1893). + if not ( + pdu.type == 'm.room.member' and + pdu.content and + pdu.content.get("membership", None) == 'join' + ): + logger.info( + "Discarding PDU %s from invalid origin %s", + pdu.event_id, origin + ) + return + else: + logger.info( + "Accepting join PDU %s from %s", + pdu.event_id, origin + ) + # Check signature. try: pdu = yield self._check_sigs_and_hash(pdu) @@ -531,20 +601,13 @@ class FederationServer(FederationBase): affected=pdu.event_id, ) - yield self.handler.on_receive_pdu(origin, pdu, get_missing=True) + yield self.handler.on_receive_pdu( + origin, pdu, get_missing=True, sent_to_us_directly=True, + ) def __str__(self): return "<ReplicationLayer(%s)>" % self.server_name - def event_from_pdu_json(self, pdu_json, outlier=False): - event = FrozenEvent( - pdu_json - ) - - event.internal_metadata.outlier = outlier - - return event - @defer.inlineCallbacks def exchange_third_party_invite( self, @@ -567,3 +630,161 @@ class FederationServer(FederationBase): origin, room_id, event_dict ) defer.returnValue(ret) + + @defer.inlineCallbacks + def check_server_matches_acl(self, server_name, room_id): + """Check if the given server is allowed by the server ACLs in the room + + Args: + server_name (str): name of server, *without any port part* + room_id (str): ID of the room to check + + Raises: + AuthError if the server does not match the ACL + """ + state_ids = yield self.store.get_current_state_ids(room_id) + acl_event_id = state_ids.get((EventTypes.ServerACL, "")) + + if not acl_event_id: + return + + acl_event = yield self.store.get_event(acl_event_id) + if server_matches_acl_event(server_name, acl_event): + return + + raise AuthError(code=403, msg="Server is banned from room") + + +def server_matches_acl_event(server_name, acl_event): + """Check if the given server is allowed by the ACL event + + Args: + server_name (str): name of server, without any port part + acl_event (EventBase): m.room.server_acl event + + Returns: + bool: True if this server is allowed by the ACLs + """ + logger.debug("Checking %s against acl %s", server_name, acl_event.content) + + # first of all, check if literal IPs are blocked, and if so, whether the + # server name is a literal IP + allow_ip_literals = acl_event.content.get("allow_ip_literals", True) + if not isinstance(allow_ip_literals, bool): + logger.warn("Ignorning non-bool allow_ip_literals flag") + allow_ip_literals = True + if not allow_ip_literals: + # check for ipv6 literals. These start with '['. + if server_name[0] == '[': + return False + + # check for ipv4 literals. We can just lift the routine from twisted. + if isIPAddress(server_name): + return False + + # next, check the deny list + deny = acl_event.content.get("deny", []) + if not isinstance(deny, (list, tuple)): + logger.warn("Ignorning non-list deny ACL %s", deny) + deny = [] + for e in deny: + if _acl_entry_matches(server_name, e): + # logger.info("%s matched deny rule %s", server_name, e) + return False + + # then the allow list. + allow = acl_event.content.get("allow", []) + if not isinstance(allow, (list, tuple)): + logger.warn("Ignorning non-list allow ACL %s", allow) + allow = [] + for e in allow: + if _acl_entry_matches(server_name, e): + # logger.info("%s matched allow rule %s", server_name, e) + return True + + # everything else should be rejected. + # logger.info("%s fell through", server_name) + return False + + +def _acl_entry_matches(server_name, acl_entry): + if not isinstance(acl_entry, six.string_types): + logger.warn("Ignoring non-str ACL entry '%s' (is %s)", acl_entry, type(acl_entry)) + return False + regex = _glob_to_regex(acl_entry) + return regex.match(server_name) + + +def _glob_to_regex(glob): + res = '' + for c in glob: + if c == '*': + res = res + '.*' + elif c == '?': + res = res + '.' + else: + res = res + re.escape(c) + return re.compile(res + "\\Z", re.IGNORECASE) + + +class FederationHandlerRegistry(object): + """Allows classes to register themselves as handlers for a given EDU or + query type for incoming federation traffic. + """ + def __init__(self): + self.edu_handlers = {} + self.query_handlers = {} + + def register_edu_handler(self, edu_type, handler): + """Sets the handler callable that will be used to handle an incoming + federation EDU of the given type. + + Args: + edu_type (str): The type of the incoming EDU to register handler for + handler (Callable[[str, dict]]): A callable invoked on incoming EDU + of the given type. The arguments are the origin server name and + the EDU contents. + """ + if edu_type in self.edu_handlers: + raise KeyError("Already have an EDU handler for %s" % (edu_type,)) + + self.edu_handlers[edu_type] = handler + + def register_query_handler(self, query_type, handler): + """Sets the handler callable that will be used to handle an incoming + federation query of the given type. + + Args: + query_type (str): Category name of the query, which should match + the string used by make_query. + handler (Callable[[dict], Deferred[dict]]): Invoked to handle + incoming queries of this type. The return will be yielded + on and the result used as the response to the query request. + """ + if query_type in self.query_handlers: + raise KeyError( + "Already have a Query handler for %s" % (query_type,) + ) + + self.query_handlers[query_type] = handler + + @defer.inlineCallbacks + def on_edu(self, edu_type, origin, content): + handler = self.edu_handlers.get(edu_type) + if not handler: + logger.warn("No handler registered for EDU type %s", edu_type) + + try: + yield handler(origin, content) + except SynapseError as e: + logger.info("Failed to handle edu %r: %r", edu_type, e) + except Exception as e: + logger.exception("Failed to handle edu %r", edu_type) + + def on_query(self, query_type, args): + handler = self.query_handlers.get(query_type) + if not handler: + logger.warn("No handler registered for query type %s", query_type) + raise NotFoundError("No handler for Query type '%s'" % (query_type,)) + + return handler(args) |