Fix perspectives requests for multiple keys for the same server (#11440)

If we tried to request multiple keys for the same server, we would end up
dropping some of those requests.

1 files changed, 19 insertions, 11 deletions

diff --git a/synapse/crypto/keyring.py b/synapse/crypto/keyring.py
index 4cda439ad9..993b04099e 100644
--- a/synapse/crypto/keyring.py
+++ b/synapse/crypto/keyring.py
@@ -667,21 +667,25 @@ class PerspectivesKeyFetcher(BaseV2KeyFetcher):
             perspective_name,
         )
 
+        request: JsonDict = {}
+        for queue_value in keys_to_fetch:
+            # there may be multiple requests for each server, so we have to merge
+            # them intelligently.
+            request_for_server = {
+                key_id: {
+                    "minimum_valid_until_ts": queue_value.minimum_valid_until_ts,
+                }
+                for key_id in queue_value.key_ids
+            }
+            request.setdefault(queue_value.server_name, {}).update(request_for_server)
+
+        logger.debug("Request to notary server %s: %s", perspective_name, request)
+
         try:
             query_response = await self.client.post_json(
                 destination=perspective_name,
                 path="/_matrix/key/v2/query",
-                data={
-                    "server_keys": {
-                        queue_value.server_name: {
-                            key_id: {
-                                "minimum_valid_until_ts": queue_value.minimum_valid_until_ts,
-                            }
-                            for key_id in queue_value.key_ids
-                        }
-                        for queue_value in keys_to_fetch
-                    }
-                },
+                data={"server_keys": request},
             )
         except (NotRetryingDestination, RequestSendFailed) as e:
             # these both have str() representations which we can't really improve upon
@@ -689,6 +693,10 @@ class PerspectivesKeyFetcher(BaseV2KeyFetcher):
         except HttpResponseException as e:
             raise KeyLookupError("Remote server returned an error: %s" % (e,))
 
+        logger.debug(
+            "Response from notary server %s: %s", perspective_name, query_response
+        )
+
         keys: Dict[str, Dict[str, FetchKeyResult]] = {}
         added_keys: List[Tuple[str, str, FetchKeyResult]] = []