Improve robustness when handling a perspective key response by deduplicating received server keys. (#15423)

* Change `store_server_verify_keys` to take a `Mapping[(str, str), FKR]`

This is because we already can't handle duplicate keys — leads to cardinality violation

* Newsfile

Signed-off-by: Olivier Wilkinson (reivilibre) <oliverw@matrix.org>

---------

Signed-off-by: Olivier Wilkinson (reivilibre) <oliverw@matrix.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/synapse/storage/databases/main/keys.py b/synapse/storage/databases/main/keys.py

index 0a19f607bd..89c37a4eb5 100644
--- a/synapse/storage/databases/main/keys.py
+++ b/synapse/storage/databases/main/keys.py
@@ -15,7 +15,7 @@
 
 import itertools
 import logging
-from typing import Any, Dict, Iterable, List, Optional, Tuple
+from typing import Any, Dict, Iterable, List, Mapping, Optional, Tuple
 
 from signedjson.key import decode_verify_key_bytes
 
@@ -95,7 +95,7 @@ class KeyStore(SQLBaseStore):
         self,
         from_server: str,
         ts_added_ms: int,
-        verify_keys: Iterable[Tuple[str, str, FetchKeyResult]],
+        verify_keys: Mapping[Tuple[str, str], FetchKeyResult],
     ) -> None:
         """Stores NACL verification keys for remote servers.
         Args:
@@ -108,7 +108,7 @@ class KeyStore(SQLBaseStore):
         key_values = []
         value_values = []
         invalidations = []
-        for server_name, key_id, fetch_result in verify_keys:
+        for (server_name, key_id), fetch_result in verify_keys.items():
             key_values.append((server_name, key_id))
             value_values.append(
                 (