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# 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.
# 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 logging
from typing import TYPE_CHECKING, List, Tuple
from synapse.api.constants import (
EventTypes,
LimitBlockingTypes,
ServerNoticeLimitReached,
ServerNoticeMsgType,
)
from synapse.api.errors import AuthError, ResourceLimitError, SynapseError
from synapse.server_notices.server_notices_manager import SERVER_NOTICE_ROOM_TAG
if TYPE_CHECKING:
from synapse.server import HomeServer
logger = logging.getLogger(__name__)
class ResourceLimitsServerNotices:
"""Keeps track of whether the server has reached it's resource limit and
ensures that the client is kept up to date.
"""
def __init__(self, hs: "HomeServer"):
self._server_notices_manager = hs.get_server_notices_manager()
self._store = hs.get_datastore()
self._auth = hs.get_auth()
self._config = hs.config
self._resouce_limited = False
self._account_data_handler = hs.get_account_data_handler()
self._message_handler = hs.get_message_handler()
self._state = hs.get_state_handler()
self._notifier = hs.get_notifier()
self._enabled = (
hs.config.limit_usage_by_mau
and self._server_notices_manager.is_enabled()
and not hs.config.hs_disabled
)
async def maybe_send_server_notice_to_user(self, user_id: str) -> None:
"""Check if we need to send a notice to this user, this will be true in
two cases.
1. The server has reached its limit does not reflect this
2. The room state indicates that the server has reached its limit when
actually the server is fine
Args:
user_id: user to check
"""
if not self._enabled:
return
timestamp = await self._store.user_last_seen_monthly_active(user_id)
if timestamp is None:
# This user will be blocked from receiving the notice anyway.
# In practice, not sure we can ever get here
return
room_id = await self._server_notices_manager.get_or_create_notice_room_for_user(
user_id
)
if not room_id:
logger.warning("Failed to get server notices room")
return
await self._check_and_set_tags(user_id, room_id)
# Determine current state of room
currently_blocked, ref_events = await self._is_room_currently_blocked(room_id)
limit_msg = None
limit_type = None
try:
# Normally should always pass in user_id to check_auth_blocking
# if you have it, but in this case are checking what would happen
# to other users if they were to arrive.
await self._auth.check_auth_blocking()
except ResourceLimitError as e:
limit_msg = e.msg
limit_type = e.limit_type
try:
if (
limit_type == LimitBlockingTypes.MONTHLY_ACTIVE_USER
and not self._config.mau_limit_alerting
):
# We have hit the MAU limit, but MAU alerting is disabled:
# reset room if necessary and return
if currently_blocked:
await self._remove_limit_block_notification(user_id, ref_events)
return
if currently_blocked and not limit_msg:
# Room is notifying of a block, when it ought not to be.
await self._remove_limit_block_notification(user_id, ref_events)
elif not currently_blocked and limit_msg:
# Room is not notifying of a block, when it ought to be.
await self._apply_limit_block_notification(
user_id, limit_msg, limit_type # type: ignore
)
except SynapseError as e:
logger.error("Error sending resource limits server notice: %s", e)
async def _remove_limit_block_notification(
self, user_id: str, ref_events: List[str]
) -> None:
"""Utility method to remove limit block notifications from the server
notices room.
Args:
user_id: user to notify
ref_events: The event_ids of pinned events that are unrelated to
limit blocking and need to be preserved.
"""
content = {"pinned": ref_events}
await self._server_notices_manager.send_notice(
user_id, content, EventTypes.Pinned, ""
)
async def _apply_limit_block_notification(
self, user_id: str, event_body: str, event_limit_type: str
) -> None:
"""Utility method to apply limit block notifications in the server
notices room.
Args:
user_id: user to notify
event_body: The human readable text that describes the block.
event_limit_type: Specifies the type of block e.g. monthly active user
limit has been exceeded.
"""
content = {
"body": event_body,
"msgtype": ServerNoticeMsgType,
"server_notice_type": ServerNoticeLimitReached,
"admin_contact": self._config.admin_contact,
"limit_type": event_limit_type,
}
event = await self._server_notices_manager.send_notice(
user_id, content, EventTypes.Message
)
content = {"pinned": [event.event_id]}
await self._server_notices_manager.send_notice(
user_id, content, EventTypes.Pinned, ""
)
async def _check_and_set_tags(self, user_id: str, room_id: str) -> None:
"""
Since server notices rooms were originally not with tags,
important to check that tags have been set correctly
Args:
user_id(str): the user in question
room_id(str): the server notices room for that user
"""
tags = await self._store.get_tags_for_room(user_id, room_id)
need_to_set_tag = True
if tags:
if SERVER_NOTICE_ROOM_TAG in tags:
# tag already present, nothing to do here
need_to_set_tag = False
if need_to_set_tag:
max_id = await self._account_data_handler.add_tag_to_room(
user_id, room_id, SERVER_NOTICE_ROOM_TAG, {}
)
self._notifier.on_new_event("account_data_key", max_id, users=[user_id])
async def _is_room_currently_blocked(self, room_id: str) -> Tuple[bool, List[str]]:
"""
Determines if the room is currently blocked
Args:
room_id: The room id of the server notices room
Returns:
bool: Is the room currently blocked
list: The list of pinned event IDs that are unrelated to limit blocking
This list can be used as a convenience in the case where the block
is to be lifted and the remaining pinned event references need to be
preserved
"""
currently_blocked = False
pinned_state_event = None
try:
pinned_state_event = await self._state.get_current_state(
room_id, event_type=EventTypes.Pinned
)
except AuthError:
# The user has yet to join the server notices room
pass
referenced_events: List[str] = []
if pinned_state_event is not None:
referenced_events = list(pinned_state_event.content.get("pinned", []))
events = await self._store.get_events(referenced_events)
for event_id, event in events.items():
if event.type != EventTypes.Message:
continue
if event.content.get("msgtype") == ServerNoticeMsgType:
currently_blocked = True
# remove event in case we need to disable blocking later on.
if event_id in referenced_events:
referenced_events.remove(event.event_id)
return currently_blocked, referenced_events
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