Allow sending custom data with read receipts

synapse/handlers/receipts.py

@@ -122,7 +122,8 @@ class ReceiptsHandler(BaseHandler):
         return True
 
     async def received_client_receipt(
-        self, room_id: str, receipt_type: str, user_id: str, event_id: str
+        self, room_id: str, receipt_type: str, user_id: str, event_id: str,
+        extra_content: Optional[JsonDict] = None,
     ) -> None:
         """Called when a client tells us a local user has read up to the given
         event_id in the room.
@@ -132,7 +133,7 @@ class ReceiptsHandler(BaseHandler):
             receipt_type=receipt_type,
             user_id=user_id,
             event_ids=[event_id],
-            data={"ts": int(self.clock.time_msec())},
+            data={"ts": int(self.clock.time_msec()), **(extra_content or {})},
         )
 
         is_new = await self._handle_new_receipts([receipt])

synapse/rest/client/v2_alpha/receipts.py

@@ -15,7 +15,7 @@
 import logging
 
 from synapse.api.errors import SynapseError
-from synapse.http.servlet import RestServlet
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
 
 from ._base import client_patterns
 
@@ -44,8 +44,10 @@ class ReceiptRestServlet(RestServlet):
 
         await self.presence_handler.bump_presence_active_time(requester.user)
 
+        body = parse_json_object_from_request(request, allow_empty_body=True)
         await self.receipts_handler.received_client_receipt(
-            room_id, receipt_type, user_id=requester.user.to_string(), event_id=event_id
+            room_id, receipt_type, user_id=requester.user.to_string(), event_id=event_id,
+            extra_content=body,
         )
 
         return 200, {}