Move ThirdPartyEventRules into module_api/callbacks (#15535)

2 files changed, 595 insertions, 0 deletions

diff --git a/synapse/module_api/callbacks/__init__.py b/synapse/module_api/callbacks/__init__.py
index 5cdb2c003a..dcb036552b 100644
--- a/synapse/module_api/callbacks/__init__.py
+++ b/synapse/module_api/callbacks/__init__.py
@@ -23,9 +23,13 @@ from synapse.module_api.callbacks.account_validity_callbacks import (
 from synapse.module_api.callbacks.spamchecker_callbacks import (
     SpamCheckerModuleApiCallbacks,
 )
+from synapse.module_api.callbacks.third_party_event_rules_callbacks import (
+    ThirdPartyEventRulesModuleApiCallbacks,
+)
 
 
 class ModuleApiCallbacks:
     def __init__(self, hs: "HomeServer") -> None:
         self.account_validity = AccountValidityModuleApiCallbacks()
         self.spam_checker = SpamCheckerModuleApiCallbacks(hs)
+        self.third_party_event_rules = ThirdPartyEventRulesModuleApiCallbacks(hs)
diff --git a/synapse/module_api/callbacks/third_party_event_rules_callbacks.py b/synapse/module_api/callbacks/third_party_event_rules_callbacks.py
new file mode 100644
index 0000000000..911f37ba42
--- /dev/null
+++ b/synapse/module_api/callbacks/third_party_event_rules_callbacks.py
@@ -0,0 +1,591 @@
+# 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 logging
+from typing import TYPE_CHECKING, Any, Awaitable, Callable, List, Optional, Tuple
+
+from twisted.internet.defer import CancelledError
+
+from synapse.api.errors import ModuleFailedException, SynapseError
+from synapse.events import EventBase
+from synapse.events.snapshot import UnpersistedEventContextBase
+from synapse.storage.roommember import ProfileInfo
+from synapse.types import Requester, StateMap
+from synapse.util.async_helpers import delay_cancellation, maybe_awaitable
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
+logger = logging.getLogger(__name__)
+
+
+CHECK_EVENT_ALLOWED_CALLBACK = Callable[
+    [EventBase, StateMap[EventBase]], Awaitable[Tuple[bool, Optional[dict]]]
+]
+ON_CREATE_ROOM_CALLBACK = Callable[[Requester, dict, bool], Awaitable]
+CHECK_THREEPID_CAN_BE_INVITED_CALLBACK = Callable[
+    [str, str, StateMap[EventBase]], Awaitable[bool]
+]
+CHECK_VISIBILITY_CAN_BE_MODIFIED_CALLBACK = Callable[
+    [str, StateMap[EventBase], str], Awaitable[bool]
+]
+ON_NEW_EVENT_CALLBACK = Callable[[EventBase, StateMap[EventBase]], Awaitable]
+CHECK_CAN_SHUTDOWN_ROOM_CALLBACK = Callable[[str, str], Awaitable[bool]]
+CHECK_CAN_DEACTIVATE_USER_CALLBACK = Callable[[str, bool], Awaitable[bool]]
+ON_PROFILE_UPDATE_CALLBACK = Callable[[str, ProfileInfo, bool, bool], Awaitable]
+ON_USER_DEACTIVATION_STATUS_CHANGED_CALLBACK = Callable[[str, bool, bool], Awaitable]
+ON_THREEPID_BIND_CALLBACK = Callable[[str, str, str], Awaitable]
+ON_ADD_USER_THIRD_PARTY_IDENTIFIER_CALLBACK = Callable[[str, str, str], Awaitable]
+ON_REMOVE_USER_THIRD_PARTY_IDENTIFIER_CALLBACK = Callable[[str, str, str], Awaitable]
+
+
+def load_legacy_third_party_event_rules(hs: "HomeServer") -> None:
+    """Wrapper that loads a third party event rules module configured using the old
+    configuration, and registers the hooks they implement.
+    """
+    if hs.config.thirdpartyrules.third_party_event_rules is None:
+        return
+
+    module, config = hs.config.thirdpartyrules.third_party_event_rules
+
+    api = hs.get_module_api()
+    third_party_rules = module(config=config, module_api=api)
+
+    # The known hooks. If a module implements a method which name appears in this set,
+    # we'll want to register it.
+    third_party_event_rules_methods = {
+        "check_event_allowed",
+        "on_create_room",
+        "check_threepid_can_be_invited",
+        "check_visibility_can_be_modified",
+    }
+
+    def async_wrapper(f: Optional[Callable]) -> Optional[Callable[..., Awaitable]]:
+        # f might be None if the callback isn't implemented by the module. In this
+        # case we don't want to register a callback at all so we return None.
+        if f is None:
+            return None
+
+        # We return a separate wrapper for these methods because, in order to wrap them
+        # correctly, we need to await its result. Therefore it doesn't make a lot of
+        # sense to make it go through the run() wrapper.
+        if f.__name__ == "check_event_allowed":
+            # We need to wrap check_event_allowed because its old form would return either
+            # a boolean or a dict, but now we want to return the dict separately from the
+            # boolean.
+            async def wrap_check_event_allowed(
+                event: EventBase,
+                state_events: StateMap[EventBase],
+            ) -> Tuple[bool, Optional[dict]]:
+                # Assertion required because mypy can't prove we won't change
+                # `f` back to `None`. See
+                # https://mypy.readthedocs.io/en/latest/common_issues.html#narrowing-and-inner-functions
+                assert f is not None
+
+                res = await f(event, state_events)
+                if isinstance(res, dict):
+                    return True, res
+                else:
+                    return res, None
+
+            return wrap_check_event_allowed
+
+        if f.__name__ == "on_create_room":
+            # We need to wrap on_create_room because its old form would return a boolean
+            # if the room creation is denied, but now we just want it to raise an
+            # exception.
+            async def wrap_on_create_room(
+                requester: Requester, config: dict, is_requester_admin: bool
+            ) -> None:
+                # Assertion required because mypy can't prove we won't change
+                # `f` back to `None`. See
+                # https://mypy.readthedocs.io/en/latest/common_issues.html#narrowing-and-inner-functions
+                assert f is not None
+
+                res = await f(requester, config, is_requester_admin)
+                if res is False:
+                    raise SynapseError(
+                        403,
+                        "Room creation forbidden with these parameters",
+                    )
+
+            return wrap_on_create_room
+
+        def run(*args: Any, **kwargs: Any) -> Awaitable:
+            # Assertion required because mypy can't prove we won't change  `f`
+            # back to `None`. See
+            # https://mypy.readthedocs.io/en/latest/common_issues.html#narrowing-and-inner-functions
+            assert f is not None
+
+            return maybe_awaitable(f(*args, **kwargs))
+
+        return run
+
+    # Register the hooks through the module API.
+    hooks = {
+        hook: async_wrapper(getattr(third_party_rules, hook, None))
+        for hook in third_party_event_rules_methods
+    }
+
+    api.register_third_party_rules_callbacks(**hooks)
+
+
+class ThirdPartyEventRulesModuleApiCallbacks:
+    """Allows server admins to provide a Python module implementing an extra
+    set of rules to apply when processing events.
+
+    This is designed to help admins of closed federations with enforcing custom
+    behaviours.
+    """
+
+    def __init__(self, hs: "HomeServer"):
+        self.store = hs.get_datastores().main
+        self._storage_controllers = hs.get_storage_controllers()
+
+        self._check_event_allowed_callbacks: List[CHECK_EVENT_ALLOWED_CALLBACK] = []
+        self._on_create_room_callbacks: List[ON_CREATE_ROOM_CALLBACK] = []
+        self._check_threepid_can_be_invited_callbacks: List[
+            CHECK_THREEPID_CAN_BE_INVITED_CALLBACK
+        ] = []
+        self._check_visibility_can_be_modified_callbacks: List[
+            CHECK_VISIBILITY_CAN_BE_MODIFIED_CALLBACK
+        ] = []
+        self._on_new_event_callbacks: List[ON_NEW_EVENT_CALLBACK] = []
+        self._check_can_shutdown_room_callbacks: List[
+            CHECK_CAN_SHUTDOWN_ROOM_CALLBACK
+        ] = []
+        self._check_can_deactivate_user_callbacks: List[
+            CHECK_CAN_DEACTIVATE_USER_CALLBACK
+        ] = []
+        self._on_profile_update_callbacks: List[ON_PROFILE_UPDATE_CALLBACK] = []
+        self._on_user_deactivation_status_changed_callbacks: List[
+            ON_USER_DEACTIVATION_STATUS_CHANGED_CALLBACK
+        ] = []
+        self._on_threepid_bind_callbacks: List[ON_THREEPID_BIND_CALLBACK] = []
+        self._on_add_user_third_party_identifier_callbacks: List[
+            ON_ADD_USER_THIRD_PARTY_IDENTIFIER_CALLBACK
+        ] = []
+        self._on_remove_user_third_party_identifier_callbacks: List[
+            ON_REMOVE_USER_THIRD_PARTY_IDENTIFIER_CALLBACK
+        ] = []
+
+    def register_third_party_rules_callbacks(
+        self,
+        check_event_allowed: Optional[CHECK_EVENT_ALLOWED_CALLBACK] = None,
+        on_create_room: Optional[ON_CREATE_ROOM_CALLBACK] = None,
+        check_threepid_can_be_invited: Optional[
+            CHECK_THREEPID_CAN_BE_INVITED_CALLBACK
+        ] = None,
+        check_visibility_can_be_modified: Optional[
+            CHECK_VISIBILITY_CAN_BE_MODIFIED_CALLBACK
+        ] = None,
+        on_new_event: Optional[ON_NEW_EVENT_CALLBACK] = None,
+        check_can_shutdown_room: Optional[CHECK_CAN_SHUTDOWN_ROOM_CALLBACK] = None,
+        check_can_deactivate_user: Optional[CHECK_CAN_DEACTIVATE_USER_CALLBACK] = None,
+        on_profile_update: Optional[ON_PROFILE_UPDATE_CALLBACK] = None,
+        on_user_deactivation_status_changed: Optional[
+            ON_USER_DEACTIVATION_STATUS_CHANGED_CALLBACK
+        ] = None,
+        on_threepid_bind: Optional[ON_THREEPID_BIND_CALLBACK] = None,
+        on_add_user_third_party_identifier: Optional[
+            ON_ADD_USER_THIRD_PARTY_IDENTIFIER_CALLBACK
+        ] = None,
+        on_remove_user_third_party_identifier: Optional[
+            ON_REMOVE_USER_THIRD_PARTY_IDENTIFIER_CALLBACK
+        ] = None,
+    ) -> None:
+        """Register callbacks from modules for each hook."""
+        if check_event_allowed is not None:
+            self._check_event_allowed_callbacks.append(check_event_allowed)
+
+        if on_create_room is not None:
+            self._on_create_room_callbacks.append(on_create_room)
+
+        if check_threepid_can_be_invited is not None:
+            self._check_threepid_can_be_invited_callbacks.append(
+                check_threepid_can_be_invited,
+            )
+
+        if check_visibility_can_be_modified is not None:
+            self._check_visibility_can_be_modified_callbacks.append(
+                check_visibility_can_be_modified,
+            )
+
+        if on_new_event is not None:
+            self._on_new_event_callbacks.append(on_new_event)
+
+        if check_can_shutdown_room is not None:
+            self._check_can_shutdown_room_callbacks.append(check_can_shutdown_room)
+
+        if check_can_deactivate_user is not None:
+            self._check_can_deactivate_user_callbacks.append(check_can_deactivate_user)
+        if on_profile_update is not None:
+            self._on_profile_update_callbacks.append(on_profile_update)
+
+        if on_user_deactivation_status_changed is not None:
+            self._on_user_deactivation_status_changed_callbacks.append(
+                on_user_deactivation_status_changed,
+            )
+
+        if on_threepid_bind is not None:
+            self._on_threepid_bind_callbacks.append(on_threepid_bind)
+
+        if on_add_user_third_party_identifier is not None:
+            self._on_add_user_third_party_identifier_callbacks.append(
+                on_add_user_third_party_identifier
+            )
+
+        if on_remove_user_third_party_identifier is not None:
+            self._on_remove_user_third_party_identifier_callbacks.append(
+                on_remove_user_third_party_identifier
+            )
+
+    async def check_event_allowed(
+        self,
+        event: EventBase,
+        context: UnpersistedEventContextBase,
+    ) -> Tuple[bool, Optional[dict]]:
+        """Check if a provided event should be allowed in the given context.
+
+        The module can return:
+            * True: the event is allowed.
+            * False: the event is not allowed, and should be rejected with M_FORBIDDEN.
+
+        If the event is allowed, the module can also return a dictionary to use as a
+        replacement for the event.
+
+        Args:
+            event: The event to be checked.
+            context: The context of the event.
+
+        Returns:
+            The result from the ThirdPartyRules module, as above.
+        """
+        # Bail out early without hitting the store if we don't have any callbacks to run.
+        if len(self._check_event_allowed_callbacks) == 0:
+            return True, None
+
+        prev_state_ids = await context.get_prev_state_ids()
+
+        # Retrieve the state events from the database.
+        events = await self.store.get_events(prev_state_ids.values())
+        state_events = {(ev.type, ev.state_key): ev for ev in events.values()}
+
+        # Ensure that the event is frozen, to make sure that the module is not tempted
+        # to try to modify it. Any attempt to modify it at this point will invalidate
+        # the hashes and signatures.
+        event.freeze()
+
+        for callback in self._check_event_allowed_callbacks:
+            try:
+                res, replacement_data = await delay_cancellation(
+                    callback(event, state_events)
+                )
+            except CancelledError:
+                raise
+            except SynapseError as e:
+                # FIXME: Being able to throw SynapseErrors is relied upon by
+                # some modules. PR #10386 accidentally broke this ability.
+                # That said, we aren't keen on exposing this implementation detail
+                # to modules and we should one day have a proper way to do what
+                # is wanted.
+                # This module callback needs a rework so that hacks such as
+                # this one are not necessary.
+                raise e
+            except Exception:
+                raise ModuleFailedException(
+                    "Failed to run `check_event_allowed` module API callback"
+                )
+
+            # Return if the event shouldn't be allowed or if the module came up with a
+            # replacement dict for the event.
+            if res is False:
+                return res, None
+            elif isinstance(replacement_data, dict):
+                return True, replacement_data
+
+        return True, None
+
+    async def on_create_room(
+        self, requester: Requester, config: dict, is_requester_admin: bool
+    ) -> None:
+        """Intercept requests to create room to maybe deny it (via an exception) or
+        update the request config.
+
+        Args:
+            requester
+            config: The creation config from the client.
+            is_requester_admin: If the requester is an admin
+        """
+        for callback in self._on_create_room_callbacks:
+            try:
+                await callback(requester, config, is_requester_admin)
+            except Exception as e:
+                # Don't silence the errors raised by this callback since we expect it to
+                # raise an exception to deny the creation of the room; instead make sure
+                # it's a SynapseError we can send to clients.
+                if not isinstance(e, SynapseError):
+                    e = SynapseError(
+                        403, "Room creation forbidden with these parameters"
+                    )
+
+                raise e
+
+    async def check_threepid_can_be_invited(
+        self, medium: str, address: str, room_id: str
+    ) -> bool:
+        """Check if a provided 3PID can be invited in the given room.
+
+        Args:
+            medium: The 3PID's medium.
+            address: The 3PID's address.
+            room_id: The room we want to invite the threepid to.
+
+        Returns:
+            True if the 3PID can be invited, False if not.
+        """
+        # Bail out early without hitting the store if we don't have any callbacks to run.
+        if len(self._check_threepid_can_be_invited_callbacks) == 0:
+            return True
+
+        state_events = await self._get_state_map_for_room(room_id)
+
+        for callback in self._check_threepid_can_be_invited_callbacks:
+            try:
+                threepid_can_be_invited = await delay_cancellation(
+                    callback(medium, address, state_events)
+                )
+                if threepid_can_be_invited is False:
+                    return False
+            except CancelledError:
+                raise
+            except Exception as e:
+                logger.warning("Failed to run module API callback %s: %s", callback, e)
+
+        return True
+
+    async def check_visibility_can_be_modified(
+        self, room_id: str, new_visibility: str
+    ) -> bool:
+        """Check if a room is allowed to be published to, or removed from, the public room
+        list.
+
+        Args:
+            room_id: The ID of the room.
+            new_visibility: The new visibility state. Either "public" or "private".
+
+        Returns:
+            True if the room's visibility can be modified, False if not.
+        """
+        # Bail out early without hitting the store if we don't have any callback
+        if len(self._check_visibility_can_be_modified_callbacks) == 0:
+            return True
+
+        state_events = await self._get_state_map_for_room(room_id)
+
+        for callback in self._check_visibility_can_be_modified_callbacks:
+            try:
+                visibility_can_be_modified = await delay_cancellation(
+                    callback(room_id, state_events, new_visibility)
+                )
+                if visibility_can_be_modified is False:
+                    return False
+            except CancelledError:
+                raise
+            except Exception as e:
+                logger.warning("Failed to run module API callback %s: %s", callback, e)
+
+        return True
+
+    async def on_new_event(self, event_id: str) -> None:
+        """Let modules act on events after they've been sent (e.g. auto-accepting
+        invites, etc.)
+
+        Args:
+            event_id: The ID of the event.
+        """
+        # Bail out early without hitting the store if we don't have any callbacks
+        if len(self._on_new_event_callbacks) == 0:
+            return
+
+        event = await self.store.get_event(event_id)
+        state_events = await self._get_state_map_for_room(event.room_id)
+
+        for callback in self._on_new_event_callbacks:
+            try:
+                await callback(event, state_events)
+            except Exception as e:
+                logger.exception(
+                    "Failed to run module API callback %s: %s", callback, e
+                )
+
+    async def check_can_shutdown_room(self, user_id: str, room_id: str) -> bool:
+        """Intercept requests to shutdown a room. If `False` is returned, the
+         room must not be shut down.
+
+        Args:
+            requester: The ID of the user requesting the shutdown.
+            room_id: The ID of the room.
+        """
+        for callback in self._check_can_shutdown_room_callbacks:
+            try:
+                can_shutdown_room = await delay_cancellation(callback(user_id, room_id))
+                if can_shutdown_room is False:
+                    return False
+            except CancelledError:
+                raise
+            except Exception as e:
+                logger.exception(
+                    "Failed to run module API callback %s: %s", callback, e
+                )
+        return True
+
+    async def check_can_deactivate_user(
+        self,
+        user_id: str,
+        by_admin: bool,
+    ) -> bool:
+        """Intercept requests to deactivate a user. If `False` is returned, the
+        user should not be deactivated.
+
+        Args:
+            requester
+            user_id: The ID of the room.
+        """
+        for callback in self._check_can_deactivate_user_callbacks:
+            try:
+                can_deactivate_user = await delay_cancellation(
+                    callback(user_id, by_admin)
+                )
+                if can_deactivate_user is False:
+                    return False
+            except CancelledError:
+                raise
+            except Exception as e:
+                logger.exception(
+                    "Failed to run module API callback %s: %s", callback, e
+                )
+        return True
+
+    async def _get_state_map_for_room(self, room_id: str) -> StateMap[EventBase]:
+        """Given a room ID, return the state events of that room.
+
+        Args:
+            room_id: The ID of the room.
+
+        Returns:
+            A dict mapping (event type, state key) to state event.
+        """
+        return await self._storage_controllers.state.get_current_state(room_id)
+
+    async def on_profile_update(
+        self, user_id: str, new_profile: ProfileInfo, by_admin: bool, deactivation: bool
+    ) -> None:
+        """Called after the global profile of a user has been updated. Does not include
+        per-room profile changes.
+
+        Args:
+            user_id: The user whose profile was changed.
+            new_profile: The updated profile for the user.
+            by_admin: Whether the profile update was performed by a server admin.
+            deactivation: Whether this change was made while deactivating the user.
+        """
+        for callback in self._on_profile_update_callbacks:
+            try:
+                await callback(user_id, new_profile, by_admin, deactivation)
+            except Exception as e:
+                logger.exception(
+                    "Failed to run module API callback %s: %s", callback, e
+                )
+
+    async def on_user_deactivation_status_changed(
+        self, user_id: str, deactivated: bool, by_admin: bool
+    ) -> None:
+        """Called after a user has been deactivated or reactivated.
+
+        Args:
+            user_id: The deactivated user.
+            deactivated: Whether the user is now deactivated.
+            by_admin: Whether the deactivation was performed by a server admin.
+        """
+        for callback in self._on_user_deactivation_status_changed_callbacks:
+            try:
+                await callback(user_id, deactivated, by_admin)
+            except Exception as e:
+                logger.exception(
+                    "Failed to run module API callback %s: %s", callback, e
+                )
+
+    async def on_threepid_bind(self, user_id: str, medium: str, address: str) -> None:
+        """Called after a threepid association has been verified and stored.
+
+        Note that this callback is called when an association is created on the
+        local homeserver, not when it's created on an identity server (and then kept track
+        of so that it can be unbound on the same IS later on).
+
+        THIS MODULE CALLBACK METHOD HAS BEEN DEPRECATED. Please use the
+        `on_add_user_third_party_identifier` callback method instead.
+
+        Args:
+            user_id: the user being associated with the threepid.
+            medium: the threepid's medium.
+            address: the threepid's address.
+        """
+        for callback in self._on_threepid_bind_callbacks:
+            try:
+                await callback(user_id, medium, address)
+            except Exception as e:
+                logger.exception(
+                    "Failed to run module API callback %s: %s", callback, e
+                )
+
+    async def on_add_user_third_party_identifier(
+        self, user_id: str, medium: str, address: str
+    ) -> None:
+        """Called when an association between a user's Matrix ID and a third-party ID
+        (email, phone number) has successfully been registered on the homeserver.
+
+        Args:
+            user_id: The User ID included in the association.
+            medium: The medium of the third-party ID (email, msisdn).
+            address: The address of the third-party ID (i.e. an email address).
+        """
+        for callback in self._on_add_user_third_party_identifier_callbacks:
+            try:
+                await callback(user_id, medium, address)
+            except Exception as e:
+                logger.exception(
+                    "Failed to run module API callback %s: %s", callback, e
+                )
+
+    async def on_remove_user_third_party_identifier(
+        self, user_id: str, medium: str, address: str
+    ) -> None:
+        """Called when an association between a user's Matrix ID and a third-party ID
+        (email, phone number) has been successfully removed on the homeserver.
+
+        This is called *after* any known bindings on identity servers for this
+        association have been removed.
+
+        Args:
+            user_id: The User ID included in the removed association.
+            medium: The medium of the third-party ID (email, msisdn).
+            address: The address of the third-party ID (i.e. an email address).
+        """
+        for callback in self._on_remove_user_third_party_identifier_callbacks:
+            try:
+                await callback(user_id, medium, address)
+            except Exception as e:
+                logger.exception(
+                    "Failed to run module API callback %s: %s", callback, e
+                )