forked-synapse/synapse/events/spamcheck.py

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# Copyright 2017 New Vector Ltd
# Copyright 2019 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.
import inspect
import logging
from typing import TYPE_CHECKING, Any, Collection, Dict, List, Optional, Tuple, Union
from synapse.rest.media.v1._base import FileInfo
from synapse.rest.media.v1.media_storage import ReadableFileWrapper
from synapse.spam_checker_api import RegistrationBehaviour
from synapse.types import RoomAlias
from synapse.util.async_helpers import maybe_awaitable
if TYPE_CHECKING:
import synapse.events
import synapse.server
logger = logging.getLogger(__name__)
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class SpamChecker:
def __init__(self, hs: "synapse.server.HomeServer"):
self.spam_checkers = [] # type: List[Any]
api = hs.get_module_api()
for module, config in hs.config.spam_checkers:
# Older spam checkers don't accept the `api` argument, so we
# try and detect support.
spam_args = inspect.getfullargspec(module)
if "api" in spam_args.args:
self.spam_checkers.append(module(config=config, api=api))
else:
self.spam_checkers.append(module(config=config))
async def check_event_for_spam(
self, event: "synapse.events.EventBase"
) -> 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
sent by a local user. If it is sent by a user on another server, then
users receive a blank event.
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Args:
event: the event to be checked
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Returns:
True or a string if the event is spammy. If a string is returned it
will be used as the error message returned to the user.
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"""
for spam_checker in self.spam_checkers:
if await maybe_awaitable(spam_checker.check_event_for_spam(event)):
return True
return False
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async def user_may_invite(
self, inviter_userid: str, invitee_userid: str, room_id: str
) -> bool:
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"""Checks if a given user may send an invite
If this method returns false, the invite will be rejected.
Args:
inviter_userid: The user ID of the sender of the invitation
invitee_userid: The user ID targeted in the invitation
room_id: The room ID
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Returns:
True if the user may send an invite, otherwise False
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"""
for spam_checker in self.spam_checkers:
if (
await maybe_awaitable(
spam_checker.user_may_invite(
inviter_userid, invitee_userid, room_id
)
)
is False
):
return False
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return True
async def user_may_create_room(self, userid: str) -> bool:
"""Checks if a given user may create a room
If this method returns false, the creation request will be rejected.
Args:
userid: The ID of the user attempting to create a room
Returns:
True if the user may create a room, otherwise False
"""
for spam_checker in self.spam_checkers:
if (
await maybe_awaitable(spam_checker.user_may_create_room(userid))
is False
):
return False
return True
async def user_may_create_room_alias(
self, userid: str, room_alias: RoomAlias
) -> bool:
"""Checks if a given user may create a room alias
If this method returns false, the association request will be rejected.
Args:
userid: The ID of the user attempting to create a room alias
room_alias: The alias to be created
Returns:
True if the user may create a room alias, otherwise False
"""
for spam_checker in self.spam_checkers:
if (
await maybe_awaitable(
spam_checker.user_may_create_room_alias(userid, room_alias)
)
is False
):
return False
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
If this method returns false, the publish request will be rejected.
Args:
userid: The user ID attempting to publish the room
room_id: The ID of the room that would be published
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Returns:
True if the user may publish the room, otherwise False
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"""
for spam_checker in self.spam_checkers:
if (
await maybe_awaitable(
spam_checker.user_may_publish_room(userid, room_id)
)
is False
):
return False
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return True
async def check_username_for_spam(self, user_profile: Dict[str, str]) -> bool:
"""Checks if a user ID or display name are considered "spammy" by this server.
If the server considers a username spammy, then it will not be included in
user directory results.
Args:
user_profile: The user information to check, it contains the keys:
* user_id
* display_name
* avatar_url
Returns:
True if the user is spammy.
"""
for spam_checker in self.spam_checkers:
# For backwards compatibility, only run if the method exists on the
# spam checker
checker = getattr(spam_checker, "check_username_for_spam", None)
if checker:
# Make a copy of the user profile object to ensure the spam checker
# cannot modify it.
if await maybe_awaitable(checker(user_profile.copy())):
return True
return False
async def check_registration_for_spam(
self,
email_threepid: Optional[dict],
username: Optional[str],
request_info: Collection[Tuple[str, str]],
auth_provider_id: Optional[str] = None,
) -> RegistrationBehaviour:
"""Checks if we should allow the given registration request.
Args:
email_threepid: The email threepid used for registering, if any
username: The request user name, if any
request_info: List of tuples of user agent and IP that
were used during the registration process.
auth_provider_id: The SSO IdP the user used, e.g "oidc", "saml",
"cas". If any. Note this does not include users registered
via a password provider.
Returns:
Enum for how the request should be handled
"""
for spam_checker in self.spam_checkers:
# For backwards compatibility, only run if the method exists on the
# spam checker
checker = getattr(spam_checker, "check_registration_for_spam", None)
if checker:
# Provide auth_provider_id if the function supports it
checker_args = inspect.signature(checker)
if len(checker_args.parameters) == 4:
d = checker(
email_threepid,
username,
request_info,
auth_provider_id,
)
elif len(checker_args.parameters) == 3:
d = checker(email_threepid, username, request_info)
else:
logger.error(
"Invalid signature for %s.check_registration_for_spam. Denying registration",
spam_checker.__module__,
)
return RegistrationBehaviour.DENY
behaviour = await maybe_awaitable(d)
assert isinstance(behaviour, RegistrationBehaviour)
if behaviour != RegistrationBehaviour.ALLOW:
return behaviour
return RegistrationBehaviour.ALLOW
async def check_media_file_for_spam(
self, file_wrapper: ReadableFileWrapper, file_info: FileInfo
) -> bool:
"""Checks if a piece of newly uploaded media should be blocked.
This will be called for local uploads, downloads of remote media, each
thumbnail generated for those, and web pages/images used for URL
previews.
Note that care should be taken to not do blocking IO operations in the
main thread. For example, to get the contents of a file a module
should do::
async def check_media_file_for_spam(
self, file: ReadableFileWrapper, file_info: FileInfo
) -> bool:
buffer = BytesIO()
await file.write_chunks_to(buffer.write)
if buffer.getvalue() == b"Hello World":
return True
return False
Args:
file: An object that allows reading the contents of the media.
file_info: Metadata about the file.
Returns:
True if the media should be blocked or False if it should be
allowed.
"""
for spam_checker in self.spam_checkers:
# For backwards compatibility, only run if the method exists on the
# spam checker
checker = getattr(spam_checker, "check_media_file_for_spam", None)
if checker:
spam = await maybe_awaitable(checker(file_wrapper, file_info))
if spam:
return True
return False