491 lines
18 KiB
Python
491 lines
18 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014 - 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from twisted.internet import defer
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from synapse.api.errors import LimitExceededError, SynapseError, AuthError
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from synapse.crypto.event_signing import add_hashes_and_signatures
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from synapse.api.constants import Membership, EventTypes
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from synapse.types import UserID, RoomAlias, Requester
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from synapse.push.action_generator import ActionGenerator
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from synapse.util.logcontext import PreserveLoggingContext
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import logging
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logger = logging.getLogger(__name__)
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VISIBILITY_PRIORITY = (
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"world_readable",
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"shared",
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"invited",
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"joined",
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)
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class BaseHandler(object):
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"""
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Common base class for the event handlers.
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:type store: synapse.storage.events.StateStore
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:type state_handler: synapse.state.StateHandler
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"""
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def __init__(self, hs):
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self.store = hs.get_datastore()
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self.auth = hs.get_auth()
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self.notifier = hs.get_notifier()
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self.state_handler = hs.get_state_handler()
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self.distributor = hs.get_distributor()
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self.ratelimiter = hs.get_ratelimiter()
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self.clock = hs.get_clock()
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self.hs = hs
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self.signing_key = hs.config.signing_key[0]
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self.server_name = hs.hostname
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self.event_builder_factory = hs.get_event_builder_factory()
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@defer.inlineCallbacks
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def filter_events_for_clients(self, user_tuples, events, event_id_to_state):
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""" Returns dict of user_id -> list of events that user is allowed to
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see.
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:param (str, bool) user_tuples: (user id, is_peeking) for each
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user to be checked. is_peeking should be true if:
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* the user is not currently a member of the room, and:
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* the user has not been a member of the room since the given
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events
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"""
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forgotten = yield defer.gatherResults([
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self.store.who_forgot_in_room(
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room_id,
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)
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for room_id in frozenset(e.room_id for e in events)
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], consumeErrors=True)
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# Set of membership event_ids that have been forgotten
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event_id_forgotten = frozenset(
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row["event_id"] for rows in forgotten for row in rows
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)
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def allowed(event, user_id, is_peeking):
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state = event_id_to_state[event.event_id]
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# get the room_visibility at the time of the event.
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visibility_event = state.get((EventTypes.RoomHistoryVisibility, ""), None)
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if visibility_event:
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visibility = visibility_event.content.get("history_visibility", "shared")
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else:
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visibility = "shared"
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if visibility not in VISIBILITY_PRIORITY:
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visibility = "shared"
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# if it was world_readable, it's easy: everyone can read it
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if visibility == "world_readable":
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return True
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# Always allow history visibility events on boundaries. This is done
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# by setting the effective visibility to the least restrictive
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# of the old vs new.
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if event.type == EventTypes.RoomHistoryVisibility:
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prev_content = event.unsigned.get("prev_content", {})
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prev_visibility = prev_content.get("history_visibility", None)
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if prev_visibility not in VISIBILITY_PRIORITY:
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prev_visibility = "shared"
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new_priority = VISIBILITY_PRIORITY.index(visibility)
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old_priority = VISIBILITY_PRIORITY.index(prev_visibility)
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if old_priority < new_priority:
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visibility = prev_visibility
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# get the user's membership at the time of the event. (or rather,
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# just *after* the event. Which means that people can see their
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# own join events, but not (currently) their own leave events.)
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membership_event = state.get((EventTypes.Member, user_id), None)
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if membership_event:
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if membership_event.event_id in event_id_forgotten:
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membership = None
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else:
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membership = membership_event.membership
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else:
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membership = None
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# if the user was a member of the room at the time of the event,
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# they can see it.
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if membership == Membership.JOIN:
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return True
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if visibility == "joined":
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# we weren't a member at the time of the event, so we can't
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# see this event.
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return False
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elif visibility == "invited":
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# user can also see the event if they were *invited* at the time
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# of the event.
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return membership == Membership.INVITE
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else:
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# visibility is shared: user can also see the event if they have
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# become a member since the event
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#
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# XXX: if the user has subsequently joined and then left again,
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# ideally we would share history up to the point they left. But
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# we don't know when they left.
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return not is_peeking
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defer.returnValue({
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user_id: [
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event
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for event in events
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if allowed(event, user_id, is_peeking)
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]
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for user_id, is_peeking in user_tuples
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})
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@defer.inlineCallbacks
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def _filter_events_for_client(self, user_id, events, is_peeking=False):
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"""
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Check which events a user is allowed to see
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:param str user_id: user id to be checked
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:param [synapse.events.EventBase] events: list of events to be checked
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:param bool is_peeking should be True if:
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* the user is not currently a member of the room, and:
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* the user has not been a member of the room since the given
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events
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:rtype [synapse.events.EventBase]
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"""
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types = (
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(EventTypes.RoomHistoryVisibility, ""),
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(EventTypes.Member, user_id),
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)
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event_id_to_state = yield self.store.get_state_for_events(
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frozenset(e.event_id for e in events),
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types=types
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)
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res = yield self.filter_events_for_clients(
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[(user_id, is_peeking)], events, event_id_to_state
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)
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defer.returnValue(res.get(user_id, []))
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def ratelimit(self, requester):
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time_now = self.clock.time()
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allowed, time_allowed = self.ratelimiter.send_message(
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requester.user.to_string(), time_now,
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msg_rate_hz=self.hs.config.rc_messages_per_second,
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burst_count=self.hs.config.rc_message_burst_count,
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)
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if not allowed:
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raise LimitExceededError(
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retry_after_ms=int(1000 * (time_allowed - time_now)),
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)
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@defer.inlineCallbacks
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def _create_new_client_event(self, builder):
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latest_ret = yield self.store.get_latest_event_ids_and_hashes_in_room(
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builder.room_id,
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)
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if latest_ret:
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depth = max([d for _, _, d in latest_ret]) + 1
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else:
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depth = 1
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prev_events = [
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(event_id, prev_hashes)
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for event_id, prev_hashes, _ in latest_ret
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]
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builder.prev_events = prev_events
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builder.depth = depth
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state_handler = self.state_handler
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context = yield state_handler.compute_event_context(builder)
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# If we've received an invite over federation, there are no latest
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# events in the room, because we don't know enough about the graph
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# fragment we received to treat it like a graph, so the above returned
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# no relevant events. It may have returned some events (if we have
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# joined and left the room), but not useful ones, like the invite.
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if (
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not self.is_host_in_room(context.current_state) and
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builder.type == EventTypes.Member
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):
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prev_member_event = yield self.store.get_room_member(
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builder.sender, builder.room_id
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)
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# The prev_member_event may already be in context.current_state,
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# despite us not being present in the room; in particular, if
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# inviting user, and all other local users, have already left.
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#
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# In that case, we have all the information we need, and we don't
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# want to drop "context" - not least because we may need to handle
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# the invite locally, which will require us to have the whole
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# context (not just prev_member_event) to auth it.
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#
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context_event_ids = (
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e.event_id for e in context.current_state.values()
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)
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if (
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prev_member_event and
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prev_member_event.event_id not in context_event_ids
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):
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# The prev_member_event is missing from context, so it must
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# have arrived over federation and is an outlier. We forcibly
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# set our context to the invite we received over federation
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builder.prev_events = (
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prev_member_event.event_id,
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prev_member_event.prev_events
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)
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context = yield state_handler.compute_event_context(
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builder,
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old_state=(prev_member_event,),
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outlier=True
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)
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if builder.is_state():
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builder.prev_state = yield self.store.add_event_hashes(
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context.prev_state_events
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)
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yield self.auth.add_auth_events(builder, context)
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add_hashes_and_signatures(
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builder, self.server_name, self.signing_key
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)
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event = builder.build()
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logger.debug(
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"Created event %s with current state: %s",
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event.event_id, context.current_state,
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)
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defer.returnValue(
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(event, context,)
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)
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def is_host_in_room(self, current_state):
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room_members = [
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(state_key, event.membership)
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for ((event_type, state_key), event) in current_state.items()
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if event_type == EventTypes.Member
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]
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if len(room_members) == 0:
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# Have we just created the room, and is this about to be the very
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# first member event?
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create_event = current_state.get(("m.room.create", ""))
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if create_event:
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return True
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for (state_key, membership) in room_members:
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if (
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UserID.from_string(state_key).domain == self.hs.hostname
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and membership == Membership.JOIN
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):
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return True
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return False
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@defer.inlineCallbacks
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def handle_new_client_event(
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self,
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requester,
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event,
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context,
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ratelimit=True,
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extra_users=[]
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):
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# We now need to go and hit out to wherever we need to hit out to.
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if ratelimit:
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self.ratelimit(requester)
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self.auth.check(event, auth_events=context.current_state)
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yield self.maybe_kick_guest_users(event, context.current_state.values())
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if event.type == EventTypes.CanonicalAlias:
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# Check the alias is acually valid (at this time at least)
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room_alias_str = event.content.get("alias", None)
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if room_alias_str:
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room_alias = RoomAlias.from_string(room_alias_str)
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directory_handler = self.hs.get_handlers().directory_handler
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mapping = yield directory_handler.get_association(room_alias)
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if mapping["room_id"] != event.room_id:
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raise SynapseError(
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400,
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"Room alias %s does not point to the room" % (
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room_alias_str,
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)
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)
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federation_handler = self.hs.get_handlers().federation_handler
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if event.type == EventTypes.Member:
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if event.content["membership"] == Membership.INVITE:
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def is_inviter_member_event(e):
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return (
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e.type == EventTypes.Member and
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e.sender == event.sender
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)
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event.unsigned["invite_room_state"] = [
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{
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"type": e.type,
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"state_key": e.state_key,
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"content": e.content,
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"sender": e.sender,
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}
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for k, e in context.current_state.items()
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if e.type in self.hs.config.room_invite_state_types
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or is_inviter_member_event(e)
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]
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invitee = UserID.from_string(event.state_key)
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if not self.hs.is_mine(invitee):
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# TODO: Can we add signature from remote server in a nicer
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# way? If we have been invited by a remote server, we need
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# to get them to sign the event.
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returned_invite = yield federation_handler.send_invite(
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invitee.domain,
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event,
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)
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event.unsigned.pop("room_state", None)
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# TODO: Make sure the signatures actually are correct.
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event.signatures.update(
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returned_invite.signatures
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)
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if event.type == EventTypes.Redaction:
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if self.auth.check_redaction(event, auth_events=context.current_state):
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original_event = yield self.store.get_event(
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event.redacts,
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check_redacted=False,
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get_prev_content=False,
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allow_rejected=False,
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allow_none=False
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)
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if event.user_id != original_event.user_id:
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raise AuthError(
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403,
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"You don't have permission to redact events"
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)
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if event.type == EventTypes.Create and context.current_state:
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raise AuthError(
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403,
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"Changing the room create event is forbidden",
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)
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action_generator = ActionGenerator(self.hs)
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yield action_generator.handle_push_actions_for_event(
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event, context, self
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)
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(event_stream_id, max_stream_id) = yield self.store.persist_event(
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event, context=context
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)
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destinations = set()
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for k, s in context.current_state.items():
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try:
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if k[0] == EventTypes.Member:
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if s.content["membership"] == Membership.JOIN:
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destinations.add(
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UserID.from_string(s.state_key).domain
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)
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except SynapseError:
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logger.warn(
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"Failed to get destination from event %s", s.event_id
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)
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with PreserveLoggingContext():
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# Don't block waiting on waking up all the listeners.
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self.notifier.on_new_room_event(
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event, event_stream_id, max_stream_id,
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extra_users=extra_users
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)
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# If invite, remove room_state from unsigned before sending.
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event.unsigned.pop("invite_room_state", None)
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federation_handler.handle_new_event(
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event, destinations=destinations,
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)
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@defer.inlineCallbacks
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def maybe_kick_guest_users(self, event, current_state):
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# Technically this function invalidates current_state by changing it.
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# Hopefully this isn't that important to the caller.
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if event.type == EventTypes.GuestAccess:
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guest_access = event.content.get("guest_access", "forbidden")
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if guest_access != "can_join":
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yield self.kick_guest_users(current_state)
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@defer.inlineCallbacks
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def kick_guest_users(self, current_state):
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for member_event in current_state:
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try:
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if member_event.type != EventTypes.Member:
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continue
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target_user = UserID.from_string(member_event.state_key)
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if not self.hs.is_mine(target_user):
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continue
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if member_event.content["membership"] not in {
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Membership.JOIN,
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Membership.INVITE
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}:
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continue
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if (
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"kind" not in member_event.content
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or member_event.content["kind"] != "guest"
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):
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continue
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# We make the user choose to leave, rather than have the
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# event-sender kick them. This is partially because we don't
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# need to worry about power levels, and partially because guest
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# users are a concept which doesn't hugely work over federation,
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# and having homeservers have their own users leave keeps more
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# of that decision-making and control local to the guest-having
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# homeserver.
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requester = Requester(target_user, "", True)
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handler = self.hs.get_handlers().room_member_handler
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yield handler.update_membership(
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requester,
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target_user,
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member_event.room_id,
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"leave",
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ratelimit=False,
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)
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except Exception as e:
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logger.warn("Error kicking guest user: %s" % (e,))
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