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.

1 files changed, 29 insertions, 1 deletions

diff --git a/synapse/module_api/__init__.py b/synapse/module_api/__init__.py

index 0861e0cfff..a885076282 100644
--- a/synapse/module_api/__init__.py
+++ b/synapse/module_api/__init__.py
@@ -18,10 +18,11 @@ from typing import TYPE_CHECKING
 
 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 @@ class ModuleApi(object):
         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