Merge commit '4876af06d' into anoa/dinsic_release_1_18_x

* commit '4876af06d':
  Abort federation requests if the client disconnects early (#7930)

changelog.d/7930.feature

@@ -0,0 +1 @@
+Abort federation requests where the client disconnects before the ratelimiter expires.

synapse/federation/transport/server.py

@@ -339,6 +339,12 @@ class BaseFederationServlet(object):
                 if origin:
                     with ratelimiter.ratelimit(origin) as d:
                         await d
+                        if request._disconnected:
+                            logger.warning(
+                                "client disconnected before we started processing "
+                                "request"
+                            )
+                            return -1, None
                         response = await func(
                             origin, content, request.args, *args, **kwargs
                         )