Store room version on invite (#6983)

When we get an invite over federation, store the room version in the rooms table.

The general idea here is that, when we pull the invite out again, we'll want to know what room_version it belongs to (so that we can later redact it if need be). So we need to store it somewhere...

synapse/replication/http/federation.py

@@ -17,6 +17,7 @@ import logging
 
 from twisted.internet import defer
 
+from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
 from synapse.events import event_type_from_format_version
 from synapse.events.snapshot import EventContext
 from synapse.http.servlet import parse_json_object_from_request
@@ -211,7 +212,7 @@ class ReplicationCleanRoomRestServlet(ReplicationEndpoint):
 
     Request format:
 
-        POST /_synapse/replication/fed_query/:fed_cleanup_room/:txn_id
+        POST /_synapse/replication/fed_cleanup_room/:room_id/:txn_id
 
         {}
     """
@@ -238,8 +239,41 @@ class ReplicationCleanRoomRestServlet(ReplicationEndpoint):
         return 200, {}
 
 
+class ReplicationStoreRoomOnInviteRestServlet(ReplicationEndpoint):
+    """Called to clean up any data in DB for a given room, ready for the
+    server to join the room.
+
+    Request format:
+
+        POST /_synapse/replication/store_room_on_invite/:room_id/:txn_id
+
+        {
+            "room_version": "1",
+        }
+    """
+
+    NAME = "store_room_on_invite"
+    PATH_ARGS = ("room_id",)
+
+    def __init__(self, hs):
+        super().__init__(hs)
+
+        self.store = hs.get_datastore()
+
+    @staticmethod
+    def _serialize_payload(room_id, room_version):
+        return {"room_version": room_version.identifier}
+
+    async def _handle_request(self, request, room_id):
+        content = parse_json_object_from_request(request)
+        room_version = KNOWN_ROOM_VERSIONS[content["room_version"]]
+        await self.store.maybe_store_room_on_invite(room_id, room_version)
+        return 200, {}
+
+
 def register_servlets(hs, http_server):
     ReplicationFederationSendEventsRestServlet(hs).register(http_server)
     ReplicationFederationSendEduRestServlet(hs).register(http_server)
     ReplicationGetQueryRestServlet(hs).register(http_server)
     ReplicationCleanRoomRestServlet(hs).register(http_server)
+    ReplicationStoreRoomOnInviteRestServlet(hs).register(http_server)