synapse-product/synapse/handlers/_base.py
Daniel Wagner-Hall 2ef6de928d Skip, rather than erroring, invalid guest requests
Erroring causes problems when people make illegal requests, because they
don't know what limit parameter they should pass.

This is definitely buggy. It leaks message counts for rooms people don't
have permission to see, via tokens. But apparently we already
consciously decided to allow that as a team, so this preserves that
behaviour.
2016-01-05 18:12:37 +00:00

344 lines
12 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2014 - 2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from twisted.internet import defer
from synapse.api.errors import LimitExceededError, SynapseError, AuthError
from synapse.crypto.event_signing import add_hashes_and_signatures
from synapse.api.constants import Membership, EventTypes
from synapse.types import UserID, RoomAlias
from synapse.util.logcontext import PreserveLoggingContext
import logging
logger = logging.getLogger(__name__)
class BaseHandler(object):
"""
Common base class for the event handlers.
:type store: synapse.storage.events.StateStore
:type state_handler: synapse.state.StateHandler
"""
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()
self.hs = hs
self.signing_key = hs.config.signing_key[0]
self.server_name = hs.hostname
self.event_builder_factory = hs.get_event_builder_factory()
@defer.inlineCallbacks
def _filter_events_for_client(self, user_id, events, is_guest=False):
# Assumes that user has at some point joined the room if not is_guest.
def allowed(event, membership, visibility):
if visibility == "world_readable":
return True
if is_guest:
return False
if membership == Membership.JOIN:
return True
if event.type == EventTypes.RoomHistoryVisibility:
return not is_guest
if visibility == "shared":
return True
elif visibility == "joined":
return membership == Membership.JOIN
elif visibility == "invited":
return membership == Membership.INVITE
return True
event_id_to_state = yield self.store.get_state_for_events(
frozenset(e.event_id for e in events),
types=(
(EventTypes.RoomHistoryVisibility, ""),
(EventTypes.Member, user_id),
)
)
events_to_return = []
for event in events:
state = event_id_to_state[event.event_id]
membership_event = state.get((EventTypes.Member, user_id), None)
if membership_event:
was_forgotten_at_event = yield self.store.was_forgotten_at(
membership_event.state_key,
membership_event.room_id,
membership_event.event_id
)
if was_forgotten_at_event:
membership = None
else:
membership = membership_event.membership
else:
membership = None
visibility_event = state.get((EventTypes.RoomHistoryVisibility, ""), None)
if visibility_event:
visibility = visibility_event.content.get("history_visibility", "shared")
else:
visibility = "shared"
should_include = allowed(event, membership, visibility)
if should_include:
events_to_return.append(event)
defer.returnValue(events_to_return)
def ratelimit(self, user_id):
time_now = self.clock.time()
allowed, time_allowed = self.ratelimiter.send_message(
user_id, time_now,
msg_rate_hz=self.hs.config.rc_messages_per_second,
burst_count=self.hs.config.rc_message_burst_count,
)
if not allowed:
raise LimitExceededError(
retry_after_ms=int(1000*(time_allowed - time_now)),
)
@defer.inlineCallbacks
def _create_new_client_event(self, builder):
latest_ret = yield self.store.get_latest_events_in_room(
builder.room_id,
)
if latest_ret:
depth = max([d for _, _, d in latest_ret]) + 1
else:
depth = 1
prev_events = [(e, h) for e, h, _ in latest_ret]
builder.prev_events = prev_events
builder.depth = depth
state_handler = self.state_handler
context = yield state_handler.compute_event_context(builder)
if builder.is_state():
builder.prev_state = yield self.store.add_event_hashes(
context.prev_state_events
)
yield self.auth.add_auth_events(builder, context)
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,)
)
@defer.inlineCallbacks
def handle_new_client_event(self, event, context, extra_destinations=[],
extra_users=[], suppress_auth=False):
# We now need to go and hit out to wherever we need to hit out to.
if not suppress_auth:
self.auth.check(event, auth_events=context.current_state)
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,
)
)
federation_handler = self.hs.get_handlers().federation_handler
if event.type == EventTypes.Member:
if event.content["membership"] == Membership.INVITE:
event.unsigned["invite_room_state"] = [
{
"type": e.type,
"state_key": e.state_key,
"content": e.content,
"sender": e.sender,
}
for k, e in context.current_state.items()
if e.type in (
EventTypes.JoinRules,
EventTypes.CanonicalAlias,
EventTypes.RoomAvatar,
EventTypes.Name,
)
]
invitee = UserID.from_string(event.state_key)
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.
returned_invite = yield federation_handler.send_invite(
invitee.domain,
event,
)
event.unsigned.pop("room_state", None)
# TODO: Make sure the signatures actually are correct.
event.signatures.update(
returned_invite.signatures
)
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"
)
(event_stream_id, max_stream_id) = yield self.store.persist_event(
event, context=context
)
destinations = set(extra_destinations)
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
)
with PreserveLoggingContext():
# Don't block waiting on waking up all the listeners.
notify_d = self.notifier.on_new_room_event(
event, event_stream_id, max_stream_id,
extra_users=extra_users
)
def log_failure(f):
logger.warn(
"Failed to notify about %s: %s",
event.event_id, f.value
)
notify_d.addErrback(log_failure)
# If invite, remove room_state from unsigned before sending.
event.unsigned.pop("invite_room_state", None)
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
if not self.hs.is_mine(UserID.from_string(member_event.state_key)):
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.
message_handler = self.hs.get_handlers().message_handler
yield message_handler.create_and_send_event(
{
"type": EventTypes.Member,
"state_key": member_event.state_key,
"content": {
"membership": Membership.LEAVE,
"kind": "guest"
},
"room_id": member_event.room_id,
"sender": member_event.state_key
},
ratelimit=False,
)
except Exception as e:
logger.warn("Error kicking guest user: %s" % (e,))