Add /state_ids federation API

The new API only returns the event_ids for the state, as most
requesters will already have the vast majority of the events already.

1 files changed, 12 insertions, 0 deletions

diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index 26fa88ae84..3ae7c48457 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -271,6 +271,17 @@ class FederationStateServlet(BaseFederationServlet):
         )
 
 
+class FederationStateIdsServlet(BaseFederationServlet):
+    PATH = "/state_ids/(?P<room_id>[^/]*)/"
+
+    def on_GET(self, origin, content, query, room_id):
+        return self.handler.on_state_ids_request(
+            origin,
+            room_id,
+            query.get("event_id", [None])[0],
+        )
+
+
 class FederationBackfillServlet(BaseFederationServlet):
     PATH = "/backfill/(?P<context>[^/]*)/"
 
@@ -538,6 +549,7 @@ SERVLET_CLASSES = (
     FederationPullServlet,
     FederationEventServlet,
     FederationStateServlet,
+    FederationStateIdsServlet,
     FederationBackfillServlet,
     FederationQueryServlet,
     FederationMakeJoinServlet,