MatrixSynapse/synapse/handlers/_base.py

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# -*- coding: utf-8 -*-
# Copyright 2014 - 2016 OpenMarket Ltd
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#
# 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.
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
from synapse.api.constants import Membership, EventTypes
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from synapse.types import UserID, RoomAlias, Requester
from synapse.push.action_generator import ActionGenerator
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from synapse.util.logcontext import PreserveLoggingContext, preserve_fn
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import logging
logger = logging.getLogger(__name__)
VISIBILITY_PRIORITY = (
"world_readable",
"shared",
"invited",
"joined",
)
MEMBERSHIP_PRIORITY = (
Membership.JOIN,
Membership.INVITE,
Membership.KNOCK,
Membership.LEAVE,
Membership.BAN,
)
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class BaseHandler(object):
"""
Common base class for the event handlers.
Attributes:
store (synapse.storage.events.StateStore):
state_handler (synapse.state.StateHandler):
"""
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def __init__(self, hs):
self.store = hs.get_datastore()
self.auth = hs.get_auth()
self.notifier = hs.get_notifier()
self.state_handler = hs.get_state_handler()
self.distributor = hs.get_distributor()
self.ratelimiter = hs.get_ratelimiter()
self.clock = hs.get_clock()
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self.hs = hs
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self.signing_key = hs.config.signing_key[0]
self.server_name = hs.hostname
self.event_builder_factory = hs.get_event_builder_factory()
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@defer.inlineCallbacks
def filter_events_for_clients(self, user_tuples, events, event_id_to_state):
""" Returns dict of user_id -> list of events that user is allowed to
see.
Args:
user_tuples (str, bool): (user id, is_peeking) for each user to be
checked. is_peeking should be true if:
* the user is not currently a member of the room, and:
* the user has not been a member of the room since the
given events
events ([synapse.events.EventBase]): list of events to filter
"""
forgotten = yield defer.gatherResults([
self.store.who_forgot_in_room(
room_id,
)
for room_id in frozenset(e.room_id for e in events)
], consumeErrors=True)
# Set of membership event_ids that have been forgotten
event_id_forgotten = frozenset(
row["event_id"] for rows in forgotten for row in rows
)
def allowed(event, user_id, is_peeking):
"""
Args:
event (synapse.events.EventBase): event to check
user_id (str)
is_peeking (bool)
"""
state = event_id_to_state[event.event_id]
# get the room_visibility at the time of the event.
visibility_event = state.get((EventTypes.RoomHistoryVisibility, ""), None)
if visibility_event:
visibility = visibility_event.content.get("history_visibility", "shared")
else:
visibility = "shared"
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if visibility not in VISIBILITY_PRIORITY:
visibility = "shared"
# if it was world_readable, it's easy: everyone can read it
if visibility == "world_readable":
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return True
# Always allow history visibility events on boundaries. This is done
# by setting the effective visibility to the least restrictive
# of the old vs new.
if event.type == EventTypes.RoomHistoryVisibility:
prev_content = event.unsigned.get("prev_content", {})
prev_visibility = prev_content.get("history_visibility", None)
if prev_visibility not in VISIBILITY_PRIORITY:
prev_visibility = "shared"
new_priority = VISIBILITY_PRIORITY.index(visibility)
old_priority = VISIBILITY_PRIORITY.index(prev_visibility)
if old_priority < new_priority:
visibility = prev_visibility
# likewise, if the event is the user's own membership event, use
# the 'most joined' membership
membership = None
if event.type == EventTypes.Member and event.state_key == user_id:
membership = event.content.get("membership", None)
if membership not in MEMBERSHIP_PRIORITY:
membership = "leave"
prev_content = event.unsigned.get("prev_content", {})
prev_membership = prev_content.get("membership", None)
if prev_membership not in MEMBERSHIP_PRIORITY:
prev_membership = "leave"
new_priority = MEMBERSHIP_PRIORITY.index(membership)
old_priority = MEMBERSHIP_PRIORITY.index(prev_membership)
if old_priority < new_priority:
membership = prev_membership
# otherwise, get the user's membership at the time of the event.
if membership is None:
membership_event = state.get((EventTypes.Member, user_id), None)
if membership_event:
if membership_event.event_id not in event_id_forgotten:
membership = membership_event.membership
# if the user was a member of the room at the time of the event,
# they can see it.
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if membership == Membership.JOIN:
return True
if visibility == "joined":
# we weren't a member at the time of the event, so we can't
# see this event.
return False
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elif visibility == "invited":
# user can also see the event if they were *invited* at the time
# of the event.
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return membership == Membership.INVITE
else:
# visibility is shared: user can also see the event if they have
# become a member since the event
#
# XXX: if the user has subsequently joined and then left again,
# ideally we would share history up to the point they left. But
# we don't know when they left.
return not is_peeking
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defer.returnValue({
user_id: [
event
for event in events
if allowed(event, user_id, is_peeking)
]
for user_id, is_peeking in user_tuples
})
@defer.inlineCallbacks
def _filter_events_for_client(self, user_id, events, is_peeking=False):
"""
Check which events a user is allowed to see
Args:
user_id(str): user id to be checked
events([synapse.events.EventBase]): list of events to be checked
is_peeking(bool): should be True if:
* the user is not currently a member of the room, and:
* the user has not been a member of the room since the given
events
Returns:
[synapse.events.EventBase]
"""
types = (
(EventTypes.RoomHistoryVisibility, ""),
(EventTypes.Member, user_id),
)
event_id_to_state = yield self.store.get_state_for_events(
frozenset(e.event_id for e in events),
types=types
)
res = yield self.filter_events_for_clients(
[(user_id, is_peeking)], events, event_id_to_state
)
defer.returnValue(res.get(user_id, []))
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def ratelimit(self, requester):
time_now = self.clock.time()
allowed, time_allowed = self.ratelimiter.send_message(
requester.user.to_string(), time_now,
msg_rate_hz=self.hs.config.rc_messages_per_second,
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burst_count=self.hs.config.rc_message_burst_count,
)
if not allowed:
raise LimitExceededError(
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retry_after_ms=int(1000 * (time_allowed - time_now)),
)
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@defer.inlineCallbacks
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def _create_new_client_event(self, builder, prev_event_ids=None):
if prev_event_ids:
prev_events = yield self.store.add_event_hashes(prev_event_ids)
prev_max_depth = yield self.store.get_max_depth_of_events(prev_event_ids)
depth = prev_max_depth + 1
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else:
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latest_ret = yield self.store.get_latest_event_ids_and_hashes_in_room(
builder.room_id,
)
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if latest_ret:
depth = max([d for _, _, d in latest_ret]) + 1
else:
depth = 1
prev_events = [
(event_id, prev_hashes)
for event_id, prev_hashes, _ in latest_ret
]
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builder.prev_events = prev_events
builder.depth = depth
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state_handler = self.state_handler
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context = yield state_handler.compute_event_context(builder)
if builder.is_state():
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builder.prev_state = yield self.store.add_event_hashes(
context.prev_state_events
)
yield self.auth.add_auth_events(builder, context)
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add_hashes_and_signatures(
builder, self.server_name, self.signing_key
)
event = builder.build()
logger.debug(
"Created event %s with current state: %s",
event.event_id, context.current_state,
)
defer.returnValue(
(event, context,)
)
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def is_host_in_room(self, current_state):
room_members = [
(state_key, event.membership)
for ((event_type, state_key), event) in current_state.items()
if event_type == EventTypes.Member
]
if len(room_members) == 0:
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# Have we just created the room, and is this about to be the very
# first member event?
create_event = current_state.get(("m.room.create", ""))
if create_event:
return True
for (state_key, membership) in room_members:
if (
UserID.from_string(state_key).domain == self.hs.hostname
and membership == Membership.JOIN
):
return True
return False
@defer.inlineCallbacks
def handle_new_client_event(
self,
requester,
event,
context,
ratelimit=True,
extra_users=[]
):
# We now need to go and hit out to wherever we need to hit out to.
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if ratelimit:
self.ratelimit(requester)
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try:
self.auth.check(event, auth_events=context.current_state)
except AuthError as err:
logger.warn("Denying new event %r because %s", event, err)
raise err
yield self.maybe_kick_guest_users(event, context.current_state.values())
if event.type == EventTypes.CanonicalAlias:
# Check the alias is acually valid (at this time at least)
room_alias_str = event.content.get("alias", None)
if room_alias_str:
room_alias = RoomAlias.from_string(room_alias_str)
directory_handler = self.hs.get_handlers().directory_handler
mapping = yield directory_handler.get_association(room_alias)
if mapping["room_id"] != event.room_id:
raise SynapseError(
400,
"Room alias %s does not point to the room" % (
room_alias_str,
)
)
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federation_handler = self.hs.get_handlers().federation_handler
if event.type == EventTypes.Member:
if event.content["membership"] == Membership.INVITE:
def is_inviter_member_event(e):
return (
e.type == EventTypes.Member and
e.sender == event.sender
)
event.unsigned["invite_room_state"] = [
{
"type": e.type,
"state_key": e.state_key,
"content": e.content,
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"sender": e.sender,
}
for k, e in context.current_state.items()
if e.type in self.hs.config.room_invite_state_types
or is_inviter_member_event(e)
]
invitee = UserID.from_string(event.state_key)
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if not self.hs.is_mine(invitee):
# TODO: Can we add signature from remote server in a nicer
# way? If we have been invited by a remote server, we need
# to get them to sign the event.
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returned_invite = yield federation_handler.send_invite(
invitee.domain,
event,
)
event.unsigned.pop("room_state", None)
# TODO: Make sure the signatures actually are correct.
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event.signatures.update(
returned_invite.signatures
)
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if event.type == EventTypes.Redaction:
if self.auth.check_redaction(event, auth_events=context.current_state):
original_event = yield self.store.get_event(
event.redacts,
check_redacted=False,
get_prev_content=False,
allow_rejected=False,
allow_none=False
)
if event.user_id != original_event.user_id:
raise AuthError(
403,
"You don't have permission to redact events"
)
if event.type == EventTypes.Create and context.current_state:
raise AuthError(
403,
"Changing the room create event is forbidden",
)
action_generator = ActionGenerator(self.hs)
yield action_generator.handle_push_actions_for_event(
event, context, self
)
(event_stream_id, max_stream_id) = yield self.store.persist_event(
event, context=context
)
# this intentionally does not yield: we don't care about the result
# and don't need to wait for it.
preserve_fn(self.hs.get_pusherpool().on_new_notifications)(
event_stream_id, max_stream_id
)
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destinations = set()
for k, s in context.current_state.items():
try:
if k[0] == EventTypes.Member:
if s.content["membership"] == Membership.JOIN:
destinations.add(
UserID.from_string(s.state_key).domain
)
except SynapseError:
logger.warn(
"Failed to get destination from event %s", s.event_id
)
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with PreserveLoggingContext():
# Don't block waiting on waking up all the listeners.
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self.notifier.on_new_room_event(
event, event_stream_id, max_stream_id,
extra_users=extra_users
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)
# If invite, remove room_state from unsigned before sending.
event.unsigned.pop("invite_room_state", None)
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federation_handler.handle_new_event(
event, destinations=destinations,
)
@defer.inlineCallbacks
def maybe_kick_guest_users(self, event, current_state):
# Technically this function invalidates current_state by changing it.
# Hopefully this isn't that important to the caller.
if event.type == EventTypes.GuestAccess:
guest_access = event.content.get("guest_access", "forbidden")
if guest_access != "can_join":
yield self.kick_guest_users(current_state)
@defer.inlineCallbacks
def kick_guest_users(self, current_state):
for member_event in current_state:
try:
if member_event.type != EventTypes.Member:
continue
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target_user = UserID.from_string(member_event.state_key)
if not self.hs.is_mine(target_user):
continue
if member_event.content["membership"] not in {
Membership.JOIN,
Membership.INVITE
}:
continue
if (
"kind" not in member_event.content
or member_event.content["kind"] != "guest"
):
continue
# We make the user choose to leave, rather than have the
# event-sender kick them. This is partially because we don't
# need to worry about power levels, and partially because guest
# users are a concept which doesn't hugely work over federation,
# and having homeservers have their own users leave keeps more
# of that decision-making and control local to the guest-having
# homeserver.
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requester = Requester(target_user, "", True)
handler = self.hs.get_handlers().room_member_handler
yield handler.update_membership(
requester,
target_user,
member_event.room_id,
"leave",
ratelimit=False,
)
except Exception as e:
logger.warn("Error kicking guest user: %s" % (e,))