Allow modules to create and send events into rooms (#8479)

This PR allows Synapse modules making use of the `ModuleApi` to create and send non-membership events into a room. This can useful to have modules send messages, or change power levels in a room etc. Note that they must send event through a user that's already in the room.

The non-membership event limitation is currently arbitrary, as it's another chunk of work and not necessary at the moment.

This commit has been cherry-picked from mainline.

changelog.d/8479.feature

@@ -0,0 +1 @@
+Add the ability to send non-membership events into a room via the `ModuleApi`.

synapse/events/third_party_rules.py

@@ -124,7 +124,9 @@ async def check_visibility_can_be_modified(
         if self.third_party_rules is None:
             return True
 
-        check_func = getattr(self.third_party_rules, "check_visibility_can_be_modified")
+        check_func = getattr(
+            self.third_party_rules, "check_visibility_can_be_modified", None
+        )
         if not check_func or not isinstance(check_func, Callable):
             return True
 

synapse/handlers/message.py

@@ -63,6 +63,7 @@
 from ._base import BaseHandler
 
 if TYPE_CHECKING:
+    from synapse.events.third_party_rules import ThirdPartyEventRules
     from synapse.server import HomeServer
 
 logger = logging.getLogger(__name__)
@@ -396,7 +397,9 @@ def __init__(self, hs: "HomeServer"):
         self.action_generator = hs.get_action_generator()
 
         self.spam_checker = hs.get_spam_checker()
-        self.third_party_event_rules = hs.get_third_party_event_rules()
+        self.third_party_event_rules = (
+            self.hs.get_third_party_event_rules()
+        )  # type: ThirdPartyEventRules
 
         self._block_events_without_consent_error = (
             self.config.block_events_without_consent_error

synapse/module_api/__init__.py

@@ -18,10 +18,11 @@
 
 from twisted.internet import defer
 
+from synapse.events import EventBase
 from synapse.http.client import SimpleHttpClient
 from synapse.http.site import SynapseRequest
 from synapse.logging.context import make_deferred_yieldable, run_in_background
-from synapse.types import UserID
+from synapse.types import JsonDict, UserID, create_requester
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
@@ -310,3 +311,30 @@ async def complete_sso_login_async(
         await self._auth_handler.complete_sso_login(
             registered_user_id, request, client_redirect_url,
         )
+
+    async def create_and_send_event_into_room(self, event_dict: JsonDict) -> EventBase:
+        """Create and send an event into a room. Membership events are currently not supported.
+
+        Args:
+            event_dict: A dictionary representing the event to send.
+                Required keys are `type`, `room_id`, `sender` and `content`.
+
+        Returns:
+            The event that was sent. If state event deduplication happened, then
+                the previous, duplicate event instead.
+
+        Raises:
+            SynapseError if the event was not allowed.
+        """
+        # Create a requester object
+        requester = create_requester(event_dict["sender"])
+
+        # Create and send the event
+        (
+            event,
+            _,
+        ) = await self._hs.get_event_creation_handler().create_and_send_nonmember_event(
+            requester, event_dict, ratelimit=False
+        )
+
+        return event

tests/module_api/test_api.py

@@ -12,9 +12,13 @@
 # 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 mock import Mock
+
+from synapse.events import EventBase
 from synapse.module_api import ModuleApi
 from synapse.rest import admin
 from synapse.rest.client.v1 import login, room
+from synapse.types import create_requester
 
 from tests.unittest import HomeserverTestCase
 
@@ -29,6 +33,7 @@ class ModuleApiTestCase(HomeserverTestCase):
     def prepare(self, reactor, clock, homeserver):
         self.store = homeserver.get_datastore()
         self.module_api = ModuleApi(homeserver, homeserver.get_auth_handler())
+        self.event_creation_handler = homeserver.get_event_creation_handler()
 
     def test_can_register_user(self):
         """Tests that an external module can register a user"""
@@ -60,6 +65,93 @@ def test_can_register_user(self):
         displayname = self.get_success(self.store.get_profile_displayname("bob"))
         self.assertEqual(displayname, "Bobberino")
 
+    def test_sending_events_into_room(self):
+        """Tests that a module can send events into a room"""
+        # Mock out create_and_send_nonmember_event to check whether events are being sent
+        self.event_creation_handler.create_and_send_nonmember_event = Mock(
+            spec=[],
+            side_effect=self.event_creation_handler.create_and_send_nonmember_event,
+        )
+
+        # Create a user and room to play with
+        user_id = self.register_user("summer", "monkey")
+        tok = self.login("summer", "monkey")
+        room_id = self.helper.create_room_as(user_id, tok=tok)
+
+        # Create and send a non-state event
+        content = {"body": "I am a puppet", "msgtype": "m.text"}
+        event_dict = {
+            "room_id": room_id,
+            "type": "m.room.message",
+            "content": content,
+            "sender": user_id,
+        }
+        event = self.get_success(
+            self.module_api.create_and_send_event_into_room(event_dict)
+        )  # type: EventBase
+        self.assertEqual(event.sender, user_id)
+        self.assertEqual(event.type, "m.room.message")
+        self.assertEqual(event.room_id, room_id)
+        self.assertFalse(hasattr(event, "state_key"))
+        self.assertDictEqual(event.content, content)
+
+        # Check that the event was sent
+        self.event_creation_handler.create_and_send_nonmember_event.assert_called_with(
+            create_requester(user_id), event_dict, ratelimit=False,
+        )
+
+        # Create and send a state event
+        content = {
+            "events_default": 0,
+            "users": {user_id: 100},
+            "state_default": 50,
+            "users_default": 0,
+            "events": {"test.event.type": 25},
+        }
+        event_dict = {
+            "room_id": room_id,
+            "type": "m.room.power_levels",
+            "content": content,
+            "sender": user_id,
+            "state_key": "",
+        }
+        event = self.get_success(
+            self.module_api.create_and_send_event_into_room(event_dict)
+        )  # type: EventBase
+        self.assertEqual(event.sender, user_id)
+        self.assertEqual(event.type, "m.room.power_levels")
+        self.assertEqual(event.room_id, room_id)
+        self.assertEqual(event.state_key, "")
+        self.assertDictEqual(event.content, content)
+
+        # Check that the event was sent
+        self.event_creation_handler.create_and_send_nonmember_event.assert_called_with(
+            create_requester(user_id),
+            {
+                "type": "m.room.power_levels",
+                "content": content,
+                "room_id": room_id,
+                "sender": user_id,
+                "state_key": "",
+            },
+            ratelimit=False,
+        )
+
+        # Check that we can't send membership events
+        content = {
+            "membership": "leave",
+        }
+        event_dict = {
+            "room_id": room_id,
+            "type": "m.room.member",
+            "content": content,
+            "sender": user_id,
+            "state_key": user_id,
+        }
+        self.get_failure(
+            self.module_api.create_and_send_event_into_room(event_dict), Exception
+        )
+
     def test_public_rooms(self):
         """Tests that a room can be added and removed from the public rooms list,
         as well as have its public rooms directory state queried.

tests/rest/client/test_third_party_rules.py

@@ -0,0 +1,170 @@
+# -*- coding: utf-8 -*-
+# 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 threading
+from typing import Dict
+
+from mock import Mock
+
+from synapse.events import EventBase
+from synapse.module_api import ModuleApi
+from synapse.rest import admin
+from synapse.rest.client.v1 import login, room
+from synapse.types import Requester, StateMap
+
+from tests import unittest
+
+thread_local = threading.local()
+
+
+class ThirdPartyRulesTestModule:
+    def __init__(self, config: Dict, module_api: ModuleApi):
+        # keep a record of the "current" rules module, so that the test can patch
+        # it if desired.
+        thread_local.rules_module = self
+        self.module_api = module_api
+
+    async def on_create_room(
+        self, requester: Requester, config: dict, is_requester_admin: bool
+    ):
+        return True
+
+    async def check_event_allowed(self, event: EventBase, state: StateMap[EventBase]):
+        return True
+
+    @staticmethod
+    def parse_config(config):
+        return config
+
+
+def current_rules_module() -> ThirdPartyRulesTestModule:
+    return thread_local.rules_module
+
+
+class ThirdPartyRulesTestCase(unittest.HomeserverTestCase):
+    servlets = [
+        admin.register_servlets,
+        login.register_servlets,
+        room.register_servlets,
+    ]
+
+    def default_config(self):
+        config = super().default_config()
+        config["third_party_event_rules"] = {
+            "module": __name__ + ".ThirdPartyRulesTestModule",
+            "config": {},
+        }
+        return config
+
+    def prepare(self, reactor, clock, homeserver):
+        # Create a user and room to play with during the tests
+        self.user_id = self.register_user("kermit", "monkey")
+        self.tok = self.login("kermit", "monkey")
+
+        self.room_id = self.helper.create_room_as(self.user_id, tok=self.tok)
+
+    def test_third_party_rules(self):
+        """Tests that a forbidden event is forbidden from being sent, but an allowed one
+        can be sent.
+        """
+        # patch the rules module with a Mock which will return False for some event
+        # types
+        async def check(ev, state):
+            return ev.type != "foo.bar.forbidden"
+
+        callback = Mock(spec=[], side_effect=check)
+        current_rules_module().check_event_allowed = callback
+
+        request, channel = self.make_request(
+            "PUT",
+            "/_matrix/client/r0/rooms/%s/send/foo.bar.allowed/1" % self.room_id,
+            {},
+            access_token=self.tok,
+        )
+        self.render(request)
+        self.assertEquals(channel.result["code"], b"200", channel.result)
+
+        callback.assert_called_once()
+
+        # there should be various state events in the state arg: do some basic checks
+        state_arg = callback.call_args[0][1]
+        for k in (("m.room.create", ""), ("m.room.member", self.user_id)):
+            self.assertIn(k, state_arg)
+            ev = state_arg[k]
+            self.assertEqual(ev.type, k[0])
+            self.assertEqual(ev.state_key, k[1])
+
+        request, channel = self.make_request(
+            "PUT",
+            "/_matrix/client/r0/rooms/%s/send/foo.bar.forbidden/1" % self.room_id,
+            {},
+            access_token=self.tok,
+        )
+        self.render(request)
+        self.assertEquals(channel.result["code"], b"403", channel.result)
+
+    def test_modify_event(self):
+        """Tests that the module can successfully tweak an event before it is persisted.
+        """
+        # first patch the event checker so that it will modify the event
+        async def check(ev: EventBase, state):
+            ev.content = {"x": "y"}
+            return True
+
+        current_rules_module().check_event_allowed = check
+
+        # now send the event
+        request, channel = self.make_request(
+            "PUT",
+            "/_matrix/client/r0/rooms/%s/send/modifyme/1" % self.room_id,
+            {"x": "x"},
+            access_token=self.tok,
+        )
+        self.render(request)
+        self.assertEqual(channel.result["code"], b"200", channel.result)
+        event_id = channel.json_body["event_id"]
+
+        # ... and check that it got modified
+        request, channel = self.make_request(
+            "GET",
+            "/_matrix/client/r0/rooms/%s/event/%s" % (self.room_id, event_id),
+            access_token=self.tok,
+        )
+        self.render(request)
+        self.assertEqual(channel.result["code"], b"200", channel.result)
+        ev = channel.json_body
+        self.assertEqual(ev["content"]["x"], "y")
+
+    def test_send_event(self):
+        """Tests that the module can send an event into a room via the module api"""
+        content = {
+            "msgtype": "m.text",
+            "body": "Hello!",
+        }
+        event_dict = {
+            "room_id": self.room_id,
+            "type": "m.room.message",
+            "content": content,
+            "sender": self.user_id,
+        }
+        event = self.get_success(
+            current_rules_module().module_api.create_and_send_event_into_room(
+                event_dict
+            )
+        )  # type: EventBase
+
+        self.assertEquals(event.sender, self.user_id)
+        self.assertEquals(event.room_id, self.room_id)
+        self.assertEquals(event.type, "m.room.message")
+        self.assertEquals(event.content, content)