mirror of
https://git.anonymousland.org/anonymousland/synapse-product.git
synced 2024-12-21 03:34:22 -05:00
a683028d81
* Correctly ratelimit invites when creating a room Also allow ratelimiting for more than one action at a time.
238 lines
10 KiB
Python
238 lines
10 KiB
Python
# Copyright 2014-2016 OpenMarket Ltd
|
|
# Copyright 2020 The Matrix.org Foundation C.I.C.
|
|
#
|
|
# 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 collections import OrderedDict
|
|
from typing import Hashable, Optional, Tuple
|
|
|
|
from synapse.api.errors import LimitExceededError
|
|
from synapse.storage.databases.main import DataStore
|
|
from synapse.types import Requester
|
|
from synapse.util import Clock
|
|
|
|
|
|
class Ratelimiter:
|
|
"""
|
|
Ratelimit actions marked by arbitrary keys.
|
|
|
|
Args:
|
|
clock: A homeserver clock, for retrieving the current time
|
|
rate_hz: The long term number of actions that can be performed in a second.
|
|
burst_count: How many actions that can be performed before being limited.
|
|
"""
|
|
|
|
def __init__(
|
|
self, store: DataStore, clock: Clock, rate_hz: float, burst_count: int
|
|
):
|
|
self.clock = clock
|
|
self.rate_hz = rate_hz
|
|
self.burst_count = burst_count
|
|
self.store = store
|
|
|
|
# A ordered dictionary keeping track of actions, when they were last
|
|
# performed and how often. Each entry is a mapping from a key of arbitrary type
|
|
# to a tuple representing:
|
|
# * How many times an action has occurred since a point in time
|
|
# * The point in time
|
|
# * The rate_hz of this particular entry. This can vary per request
|
|
self.actions = (
|
|
OrderedDict()
|
|
) # type: OrderedDict[Hashable, Tuple[float, int, float]]
|
|
|
|
async def can_do_action(
|
|
self,
|
|
requester: Optional[Requester],
|
|
key: Optional[Hashable] = None,
|
|
rate_hz: Optional[float] = None,
|
|
burst_count: Optional[int] = None,
|
|
update: bool = True,
|
|
n_actions: int = 1,
|
|
_time_now_s: Optional[int] = None,
|
|
) -> Tuple[bool, float]:
|
|
"""Can the entity (e.g. user or IP address) perform the action?
|
|
|
|
Checks if the user has ratelimiting disabled in the database by looking
|
|
for null/zero values in the `ratelimit_override` table. (Non-zero
|
|
values aren't honoured, as they're specific to the event sending
|
|
ratelimiter, rather than all ratelimiters)
|
|
|
|
Args:
|
|
requester: The requester that is doing the action, if any. Used to check
|
|
if the user has ratelimits disabled in the database.
|
|
key: An arbitrary key used to classify an action. Defaults to the
|
|
requester's user ID.
|
|
rate_hz: The long term number of actions that can be performed in a second.
|
|
Overrides the value set during instantiation if set.
|
|
burst_count: How many actions that can be performed before being limited.
|
|
Overrides the value set during instantiation if set.
|
|
update: Whether to count this check as performing the action
|
|
n_actions: The number of times the user wants to do this action. If the user
|
|
cannot do all of the actions, the user's action count is not incremented
|
|
at all.
|
|
_time_now_s: The current time. Optional, defaults to the current time according
|
|
to self.clock. Only used by tests.
|
|
|
|
Returns:
|
|
A tuple containing:
|
|
* A bool indicating if they can perform the action now
|
|
* The reactor timestamp for when the action can be performed next.
|
|
-1 if rate_hz is less than or equal to zero
|
|
"""
|
|
if key is None:
|
|
if not requester:
|
|
raise ValueError("Must supply at least one of `requester` or `key`")
|
|
|
|
key = requester.user.to_string()
|
|
|
|
if requester:
|
|
# Disable rate limiting of users belonging to any AS that is configured
|
|
# not to be rate limited in its registration file (rate_limited: true|false).
|
|
if requester.app_service and not requester.app_service.is_rate_limited():
|
|
return True, -1.0
|
|
|
|
# Check if ratelimiting has been disabled for the user.
|
|
#
|
|
# Note that we don't use the returned rate/burst count, as the table
|
|
# is specifically for the event sending ratelimiter. Instead, we
|
|
# only use it to (somewhat cheekily) infer whether the user should
|
|
# be subject to any rate limiting or not.
|
|
override = await self.store.get_ratelimit_for_user(
|
|
requester.authenticated_entity
|
|
)
|
|
if override and not override.messages_per_second:
|
|
return True, -1.0
|
|
|
|
# Override default values if set
|
|
time_now_s = _time_now_s if _time_now_s is not None else self.clock.time()
|
|
rate_hz = rate_hz if rate_hz is not None else self.rate_hz
|
|
burst_count = burst_count if burst_count is not None else self.burst_count
|
|
|
|
# Remove any expired entries
|
|
self._prune_message_counts(time_now_s)
|
|
|
|
# Check if there is an existing count entry for this key
|
|
action_count, time_start, _ = self.actions.get(key, (0.0, time_now_s, 0.0))
|
|
|
|
# Check whether performing another action is allowed
|
|
time_delta = time_now_s - time_start
|
|
performed_count = action_count - time_delta * rate_hz
|
|
if performed_count < 0:
|
|
performed_count = 0
|
|
time_start = time_now_s
|
|
|
|
# This check would be easier read as performed_count + n_actions > burst_count,
|
|
# but performed_count might be a very precise float (with lots of numbers
|
|
# following the point) in which case Python might round it up when adding it to
|
|
# n_actions. Writing it this way ensures it doesn't happen.
|
|
if performed_count > burst_count - n_actions:
|
|
# Deny, we have exceeded our burst count
|
|
allowed = False
|
|
else:
|
|
# We haven't reached our limit yet
|
|
allowed = True
|
|
action_count = performed_count + n_actions
|
|
|
|
if update:
|
|
self.actions[key] = (action_count, time_start, rate_hz)
|
|
|
|
if rate_hz > 0:
|
|
# Find out when the count of existing actions expires
|
|
time_allowed = time_start + (action_count - burst_count + 1) / rate_hz
|
|
|
|
# Don't give back a time in the past
|
|
if time_allowed < time_now_s:
|
|
time_allowed = time_now_s
|
|
|
|
else:
|
|
# XXX: Why is this -1? This seems to only be used in
|
|
# self.ratelimit. I guess so that clients get a time in the past and don't
|
|
# feel afraid to try again immediately
|
|
time_allowed = -1
|
|
|
|
return allowed, time_allowed
|
|
|
|
def _prune_message_counts(self, time_now_s: int):
|
|
"""Remove message count entries that have not exceeded their defined
|
|
rate_hz limit
|
|
|
|
Args:
|
|
time_now_s: The current time
|
|
"""
|
|
# We create a copy of the key list here as the dictionary is modified during
|
|
# the loop
|
|
for key in list(self.actions.keys()):
|
|
action_count, time_start, rate_hz = self.actions[key]
|
|
|
|
# Rate limit = "seconds since we started limiting this action" * rate_hz
|
|
# If this limit has not been exceeded, wipe our record of this action
|
|
time_delta = time_now_s - time_start
|
|
if action_count - time_delta * rate_hz > 0:
|
|
continue
|
|
else:
|
|
del self.actions[key]
|
|
|
|
async def ratelimit(
|
|
self,
|
|
requester: Optional[Requester],
|
|
key: Optional[Hashable] = None,
|
|
rate_hz: Optional[float] = None,
|
|
burst_count: Optional[int] = None,
|
|
update: bool = True,
|
|
n_actions: int = 1,
|
|
_time_now_s: Optional[int] = None,
|
|
):
|
|
"""Checks if an action can be performed. If not, raises a LimitExceededError
|
|
|
|
Checks if the user has ratelimiting disabled in the database by looking
|
|
for null/zero values in the `ratelimit_override` table. (Non-zero
|
|
values aren't honoured, as they're specific to the event sending
|
|
ratelimiter, rather than all ratelimiters)
|
|
|
|
Args:
|
|
requester: The requester that is doing the action, if any. Used to check for
|
|
if the user has ratelimits disabled.
|
|
key: An arbitrary key used to classify an action. Defaults to the
|
|
requester's user ID.
|
|
rate_hz: The long term number of actions that can be performed in a second.
|
|
Overrides the value set during instantiation if set.
|
|
burst_count: How many actions that can be performed before being limited.
|
|
Overrides the value set during instantiation if set.
|
|
update: Whether to count this check as performing the action
|
|
n_actions: The number of times the user wants to do this action. If the user
|
|
cannot do all of the actions, the user's action count is not incremented
|
|
at all.
|
|
_time_now_s: The current time. Optional, defaults to the current time according
|
|
to self.clock. Only used by tests.
|
|
|
|
Raises:
|
|
LimitExceededError: If an action could not be performed, along with the time in
|
|
milliseconds until the action can be performed again
|
|
"""
|
|
time_now_s = _time_now_s if _time_now_s is not None else self.clock.time()
|
|
|
|
allowed, time_allowed = await self.can_do_action(
|
|
requester,
|
|
key,
|
|
rate_hz=rate_hz,
|
|
burst_count=burst_count,
|
|
update=update,
|
|
n_actions=n_actions,
|
|
_time_now_s=time_now_s,
|
|
)
|
|
|
|
if not allowed:
|
|
raise LimitExceededError(
|
|
retry_after_ms=int(1000 * (time_allowed - time_now_s))
|
|
)
|