Fix `PushRuleEvaluator` and `Filter` to work on frozendicts (#12100)

* Fix `PushRuleEvaluator` to work on frozendicts

frozendicts do not (necessarily) inherit from dict, so this needs to handle
them correctly.

* Fix event filtering for frozen events

Looks like this one was introduced by #11194.

2 files changed, 7 insertions, 6 deletions

diff --git a/synapse/api/filtering.py b/synapse/api/filtering.py
index fe4cc2e8ee..cb532d7238 100644
--- a/synapse/api/filtering.py
+++ b/synapse/api/filtering.py
@@ -22,6 +22,7 @@ from typing import (
     Dict,
     Iterable,
     List,
+    Mapping,
     Optional,
     Set,
     TypeVar,
@@ -361,10 +362,10 @@ class Filter:
             return self._check_fields(field_matchers)
         else:
             content = event.get("content")
-            # Content is assumed to be a dict below, so ensure it is. This should
+            # Content is assumed to be a mapping below, so ensure it is. This should
             # always be true for events, but account_data has been allowed to
             # have non-dict content.
-            if not isinstance(content, dict):
+            if not isinstance(content, Mapping):
                 content = {}
 
             sender = event.get("sender", None)
diff --git a/synapse/push/push_rule_evaluator.py b/synapse/push/push_rule_evaluator.py
index 659a53805d..f617c759e6 100644
--- a/synapse/push/push_rule_evaluator.py
+++ b/synapse/push/push_rule_evaluator.py
@@ -15,12 +15,12 @@
 
 import logging
 import re
-from typing import Any, Dict, List, Optional, Pattern, Tuple, Union
+from typing import Any, Dict, List, Mapping, Optional, Pattern, Tuple, Union
 
 from matrix_common.regex import glob_to_regex, to_word_pattern
 
 from synapse.events import EventBase
-from synapse.types import JsonDict, UserID
+from synapse.types import UserID
 from synapse.util.caches.lrucache import LruCache
 
 logger = logging.getLogger(__name__)
@@ -223,7 +223,7 @@ def _glob_matches(glob: str, value: str, word_boundary: bool = False) -> bool:
 
 
 def _flatten_dict(
-    d: Union[EventBase, JsonDict],
+    d: Union[EventBase, Mapping[str, Any]],
     prefix: Optional[List[str]] = None,
     result: Optional[Dict[str, str]] = None,
 ) -> Dict[str, str]:
@@ -234,7 +234,7 @@ def _flatten_dict(
     for key, value in d.items():
         if isinstance(value, str):
             result[".".join(prefix + [key])] = value.lower()
-        elif isinstance(value, dict):
+        elif isinstance(value, Mapping):
             _flatten_dict(value, prefix=(prefix + [key]), result=result)
 
     return result