Factor out an `is_mine_server_name` method (#15542)

Add an `is_mine_server_name` method, similar to `is_mine_id`.

Ideally we would use this consistently, instead of sometimes comparing
against `hs.hostname` and other times reaching into
`hs.config.server.server_name`.

Also fix a bug in the tests where `hs.hostname` would sometimes differ
from `hs.config.server.server_name`.

Signed-off-by: Sean Quah <seanq@matrix.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/synapse/handlers/federation_event.py b/synapse/handlers/federation_event.py
index fc15024166..06343d40e4 100644
--- a/synapse/handlers/federation_event.py
+++ b/synapse/handlers/federation_event.py
@@ -163,6 +163,7 @@ class FederationEventHandler:
         self._notifier = hs.get_notifier()
 
         self._is_mine_id = hs.is_mine_id
+        self._is_mine_server_name = hs.is_mine_server_name
         self._server_name = hs.hostname
         self._instance_name = hs.get_instance_name()
 
@@ -688,7 +689,7 @@ class FederationEventHandler:
         server from invalid events (there is probably no point in trying to
         re-fetch invalid events from every other HS in the room.)
         """
-        if dest == self._server_name:
+        if self._is_mine_server_name(dest):
             raise SynapseError(400, "Can't backfill from self.")
 
         events = await self._federation_client.backfill(