419 lines
15 KiB
Python
419 lines
15 KiB
Python
# Copyright 2017 New Vector Ltd
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# Copyright 2019 The Matrix.org Foundation C.I.C.
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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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import inspect
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import logging
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from typing import (
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TYPE_CHECKING,
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Any,
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Awaitable,
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Callable,
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Collection,
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Dict,
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List,
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Optional,
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Tuple,
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Union,
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)
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from synapse.rest.media.v1._base import FileInfo
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from synapse.rest.media.v1.media_storage import ReadableFileWrapper
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from synapse.spam_checker_api import RegistrationBehaviour
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from synapse.types import RoomAlias
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from synapse.util.async_helpers import maybe_awaitable
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if TYPE_CHECKING:
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import synapse.events
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import synapse.server
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logger = logging.getLogger(__name__)
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CHECK_EVENT_FOR_SPAM_CALLBACK = Callable[
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["synapse.events.EventBase"],
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Awaitable[Union[bool, str]],
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]
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USER_MAY_INVITE_CALLBACK = Callable[[str, str, str], Awaitable[bool]]
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USER_MAY_CREATE_ROOM_CALLBACK = Callable[[str], Awaitable[bool]]
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USER_MAY_CREATE_ROOM_ALIAS_CALLBACK = Callable[[str, RoomAlias], Awaitable[bool]]
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USER_MAY_PUBLISH_ROOM_CALLBACK = Callable[[str, str], Awaitable[bool]]
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CHECK_USERNAME_FOR_SPAM_CALLBACK = Callable[[Dict[str, str]], Awaitable[bool]]
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LEGACY_CHECK_REGISTRATION_FOR_SPAM_CALLBACK = Callable[
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[
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Optional[dict],
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Optional[str],
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Collection[Tuple[str, str]],
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],
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Awaitable[RegistrationBehaviour],
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]
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CHECK_REGISTRATION_FOR_SPAM_CALLBACK = Callable[
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[
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Optional[dict],
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Optional[str],
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Collection[Tuple[str, str]],
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Optional[str],
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],
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Awaitable[RegistrationBehaviour],
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]
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CHECK_MEDIA_FILE_FOR_SPAM_CALLBACK = Callable[
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[ReadableFileWrapper, FileInfo],
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Awaitable[bool],
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]
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def load_legacy_spam_checkers(hs: "synapse.server.HomeServer"):
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"""Wrapper that loads spam checkers configured using the old configuration, and
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registers the spam checker hooks they implement.
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"""
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spam_checkers: List[Any] = []
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api = hs.get_module_api()
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for module, config in hs.config.spam_checkers:
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# Older spam checkers don't accept the `api` argument, so we
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# try and detect support.
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spam_args = inspect.getfullargspec(module)
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if "api" in spam_args.args:
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spam_checkers.append(module(config=config, api=api))
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else:
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spam_checkers.append(module(config=config))
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# The known spam checker hooks. If a spam checker module implements a method
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# which name appears in this set, we'll want to register it.
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spam_checker_methods = {
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"check_event_for_spam",
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"user_may_invite",
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"user_may_create_room",
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"user_may_create_room_alias",
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"user_may_publish_room",
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"check_username_for_spam",
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"check_registration_for_spam",
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"check_media_file_for_spam",
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}
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for spam_checker in spam_checkers:
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# Methods on legacy spam checkers might not be async, so we wrap them around a
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# wrapper that will call maybe_awaitable on the result.
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def async_wrapper(f: Optional[Callable]) -> Optional[Callable[..., Awaitable]]:
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# f might be None if the callback isn't implemented by the module. In this
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# case we don't want to register a callback at all so we return None.
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if f is None:
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return None
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wrapped_func = f
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if f.__name__ == "check_registration_for_spam":
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checker_args = inspect.signature(f)
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if len(checker_args.parameters) == 3:
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# Backwards compatibility; some modules might implement a hook that
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# doesn't expect a 4th argument. In this case, wrap it in a function
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# that gives it only 3 arguments and drops the auth_provider_id on
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# the floor.
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def wrapper(
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email_threepid: Optional[dict],
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username: Optional[str],
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request_info: Collection[Tuple[str, str]],
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auth_provider_id: Optional[str],
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) -> Union[Awaitable[RegistrationBehaviour], RegistrationBehaviour]:
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# We've already made sure f is not None above, but mypy doesn't
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# do well across function boundaries so we need to tell it f is
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# definitely not None.
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assert f is not None
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return f(
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email_threepid,
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username,
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request_info,
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)
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wrapped_func = wrapper
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elif len(checker_args.parameters) != 4:
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raise RuntimeError(
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"Bad signature for callback check_registration_for_spam",
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)
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def run(*args, **kwargs):
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# mypy doesn't do well across function boundaries so we need to tell it
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# wrapped_func is definitely not None.
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assert wrapped_func is not None
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return maybe_awaitable(wrapped_func(*args, **kwargs))
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return run
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# Register the hooks through the module API.
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hooks = {
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hook: async_wrapper(getattr(spam_checker, hook, None))
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for hook in spam_checker_methods
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}
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api.register_spam_checker_callbacks(**hooks)
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class SpamChecker:
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def __init__(self):
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self._check_event_for_spam_callbacks: List[CHECK_EVENT_FOR_SPAM_CALLBACK] = []
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self._user_may_invite_callbacks: List[USER_MAY_INVITE_CALLBACK] = []
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self._user_may_create_room_callbacks: List[USER_MAY_CREATE_ROOM_CALLBACK] = []
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self._user_may_create_room_alias_callbacks: List[
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USER_MAY_CREATE_ROOM_ALIAS_CALLBACK
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] = []
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self._user_may_publish_room_callbacks: List[USER_MAY_PUBLISH_ROOM_CALLBACK] = []
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self._check_username_for_spam_callbacks: List[
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CHECK_USERNAME_FOR_SPAM_CALLBACK
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] = []
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self._check_registration_for_spam_callbacks: List[
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CHECK_REGISTRATION_FOR_SPAM_CALLBACK
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] = []
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self._check_media_file_for_spam_callbacks: List[
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CHECK_MEDIA_FILE_FOR_SPAM_CALLBACK
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] = []
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def register_callbacks(
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self,
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check_event_for_spam: Optional[CHECK_EVENT_FOR_SPAM_CALLBACK] = None,
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user_may_invite: Optional[USER_MAY_INVITE_CALLBACK] = None,
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user_may_create_room: Optional[USER_MAY_CREATE_ROOM_CALLBACK] = None,
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user_may_create_room_alias: Optional[
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USER_MAY_CREATE_ROOM_ALIAS_CALLBACK
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] = None,
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user_may_publish_room: Optional[USER_MAY_PUBLISH_ROOM_CALLBACK] = None,
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check_username_for_spam: Optional[CHECK_USERNAME_FOR_SPAM_CALLBACK] = None,
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check_registration_for_spam: Optional[
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CHECK_REGISTRATION_FOR_SPAM_CALLBACK
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] = None,
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check_media_file_for_spam: Optional[CHECK_MEDIA_FILE_FOR_SPAM_CALLBACK] = None,
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):
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"""Register callbacks from module for each hook."""
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if check_event_for_spam is not None:
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self._check_event_for_spam_callbacks.append(check_event_for_spam)
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if user_may_invite is not None:
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self._user_may_invite_callbacks.append(user_may_invite)
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if user_may_create_room is not None:
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self._user_may_create_room_callbacks.append(user_may_create_room)
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if user_may_create_room_alias is not None:
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self._user_may_create_room_alias_callbacks.append(
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user_may_create_room_alias,
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)
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if user_may_publish_room is not None:
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self._user_may_publish_room_callbacks.append(user_may_publish_room)
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if check_username_for_spam is not None:
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self._check_username_for_spam_callbacks.append(check_username_for_spam)
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if check_registration_for_spam is not None:
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self._check_registration_for_spam_callbacks.append(
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check_registration_for_spam,
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)
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if check_media_file_for_spam is not None:
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self._check_media_file_for_spam_callbacks.append(check_media_file_for_spam)
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async def check_event_for_spam(
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self, event: "synapse.events.EventBase"
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) -> Union[bool, str]:
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"""Checks if a given event is considered "spammy" by this server.
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If the server considers an event spammy, then it will be rejected if
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sent by a local user. If it is sent by a user on another server, then
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users receive a blank event.
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Args:
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event: the event to be checked
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Returns:
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True or a string if the event is spammy. If a string is returned it
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will be used as the error message returned to the user.
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"""
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for callback in self._check_event_for_spam_callbacks:
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res: Union[bool, str] = await callback(event)
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if res:
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return res
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return False
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async def user_may_invite(
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self, inviter_userid: str, invitee_userid: str, room_id: str
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) -> bool:
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"""Checks if a given user may send an invite
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If this method returns false, the invite will be rejected.
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Args:
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inviter_userid: The user ID of the sender of the invitation
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invitee_userid: The user ID targeted in the invitation
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room_id: The room ID
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Returns:
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True if the user may send an invite, otherwise False
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"""
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for callback in self._user_may_invite_callbacks:
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if await callback(inviter_userid, invitee_userid, room_id) is False:
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return False
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return True
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async def user_may_create_room(self, userid: str) -> bool:
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"""Checks if a given user may create a room
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If this method returns false, the creation request will be rejected.
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Args:
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userid: The ID of the user attempting to create a room
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Returns:
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True if the user may create a room, otherwise False
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"""
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for callback in self._user_may_create_room_callbacks:
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if await callback(userid) is False:
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return False
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return True
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async def user_may_create_room_alias(
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self, userid: str, room_alias: RoomAlias
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) -> bool:
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"""Checks if a given user may create a room alias
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If this method returns false, the association request will be rejected.
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Args:
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userid: The ID of the user attempting to create a room alias
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room_alias: The alias to be created
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Returns:
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True if the user may create a room alias, otherwise False
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"""
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for callback in self._user_may_create_room_alias_callbacks:
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if await callback(userid, room_alias) is False:
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return False
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return True
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async def user_may_publish_room(self, userid: str, room_id: str) -> bool:
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"""Checks if a given user may publish a room to the directory
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If this method returns false, the publish request will be rejected.
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Args:
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userid: The user ID attempting to publish the room
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room_id: The ID of the room that would be published
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Returns:
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True if the user may publish the room, otherwise False
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"""
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for callback in self._user_may_publish_room_callbacks:
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if await callback(userid, room_id) is False:
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return False
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return True
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async def check_username_for_spam(self, user_profile: Dict[str, str]) -> bool:
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"""Checks if a user ID or display name are considered "spammy" by this server.
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If the server considers a username spammy, then it will not be included in
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user directory results.
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Args:
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user_profile: The user information to check, it contains the keys:
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* user_id
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* display_name
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* avatar_url
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Returns:
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True if the user is spammy.
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"""
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for callback in self._check_username_for_spam_callbacks:
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# Make a copy of the user profile object to ensure the spam checker cannot
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# modify it.
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if await callback(user_profile.copy()):
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return True
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return False
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async def check_registration_for_spam(
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self,
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email_threepid: Optional[dict],
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username: Optional[str],
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request_info: Collection[Tuple[str, str]],
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auth_provider_id: Optional[str] = None,
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) -> RegistrationBehaviour:
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"""Checks if we should allow the given registration request.
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Args:
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email_threepid: The email threepid used for registering, if any
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username: The request user name, if any
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request_info: List of tuples of user agent and IP that
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were used during the registration process.
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auth_provider_id: The SSO IdP the user used, e.g "oidc", "saml",
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"cas". If any. Note this does not include users registered
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via a password provider.
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Returns:
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Enum for how the request should be handled
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"""
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for callback in self._check_registration_for_spam_callbacks:
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behaviour = await (
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callback(email_threepid, username, request_info, auth_provider_id)
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)
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assert isinstance(behaviour, RegistrationBehaviour)
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if behaviour != RegistrationBehaviour.ALLOW:
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return behaviour
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return RegistrationBehaviour.ALLOW
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async def check_media_file_for_spam(
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self, file_wrapper: ReadableFileWrapper, file_info: FileInfo
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) -> bool:
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"""Checks if a piece of newly uploaded media should be blocked.
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This will be called for local uploads, downloads of remote media, each
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thumbnail generated for those, and web pages/images used for URL
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previews.
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Note that care should be taken to not do blocking IO operations in the
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main thread. For example, to get the contents of a file a module
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should do::
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async def check_media_file_for_spam(
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self, file: ReadableFileWrapper, file_info: FileInfo
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) -> bool:
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buffer = BytesIO()
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await file.write_chunks_to(buffer.write)
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if buffer.getvalue() == b"Hello World":
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return True
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return False
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Args:
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file: An object that allows reading the contents of the media.
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file_info: Metadata about the file.
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Returns:
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True if the media should be blocked or False if it should be
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allowed.
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"""
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for callback in self._check_media_file_for_spam_callbacks:
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spam = await callback(file_wrapper, file_info)
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if spam:
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return True
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return False
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