Support for MSC3758: exact_event_match push condition (#14964)

This specifies to search for an exact value match, instead of
string globbing. It only works across non-compound JSON values
(null, boolean, integer, and strings).

3 files changed, 18 insertions, 7 deletions

diff --git a/synapse/config/experimental.py b/synapse/config/experimental.py
index 5e3a889081..6ac2f0c10d 100644
--- a/synapse/config/experimental.py
+++ b/synapse/config/experimental.py
@@ -169,6 +169,11 @@ class ExperimentalConfig(Config):
         # MSC3925: do not replace events with their edits
         self.msc3925_inhibit_edit = experimental.get("msc3925_inhibit_edit", False)
 
+        # MSC3758: exact_event_match push rule condition
+        self.msc3758_exact_event_match = experimental.get(
+            "msc3758_exact_event_match", False
+        )
+
         # MSC3873: Disambiguate event_match keys.
         self.msc3783_escape_event_match_key = experimental.get(
             "msc3783_escape_event_match_key", False
diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index 39d2f88f03..8568aca528 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -43,6 +43,7 @@ from synapse.events.snapshot import EventContext
 from synapse.state import POWER_KEY
 from synapse.storage.databases.main.roommember import EventIdMembership
 from synapse.synapse_rust.push import FilteredPushRules, PushRuleEvaluator
+from synapse.types import SimpleJsonValue
 from synapse.types.state import StateFilter
 from synapse.util.caches import register_cache
 from synapse.util.metrics import measure_func
@@ -256,13 +257,15 @@ class BulkPushRuleEvaluator:
 
         return pl_event.content if pl_event else {}, sender_level
 
-    async def _related_events(self, event: EventBase) -> Dict[str, Dict[str, str]]:
+    async def _related_events(
+        self, event: EventBase
+    ) -> Dict[str, Dict[str, SimpleJsonValue]]:
         """Fetches the related events for 'event'. Sets the im.vector.is_falling_back key if the event is from a fallback relation
 
         Returns:
             Mapping of relation type to flattened events.
         """
-        related_events: Dict[str, Dict[str, str]] = {}
+        related_events: Dict[str, Dict[str, SimpleJsonValue]] = {}
         if self._related_event_match_enabled:
             related_event_id = event.content.get("m.relates_to", {}).get("event_id")
             relation_type = event.content.get("m.relates_to", {}).get("rel_type")
@@ -425,6 +428,7 @@ class BulkPushRuleEvaluator:
             self._related_event_match_enabled,
             event.room_version.msc3931_push_features,
             self.hs.config.experimental.msc1767_enabled,  # MSC3931 flag
+            self.hs.config.experimental.msc3758_exact_event_match,
         )
 
         users = rules_by_user.keys()
@@ -501,15 +505,15 @@ StateGroup = Union[object, int]
 def _flatten_dict(
     d: Union[EventBase, Mapping[str, Any]],
     prefix: Optional[List[str]] = None,
-    result: Optional[Dict[str, str]] = None,
+    result: Optional[Dict[str, SimpleJsonValue]] = None,
     *,
     msc3783_escape_event_match_key: bool = False,
-) -> Dict[str, str]:
+) -> Dict[str, SimpleJsonValue]:
     """
     Given a JSON dictionary (or event) which might contain sub dictionaries,
     flatten it into a single layer dictionary by combining the keys & sub-keys.
 
-    Any (non-dictionary), non-string value is dropped.
+    String, integer, boolean, and null values are kept. All others are dropped.
 
     Transforms:
 
@@ -538,8 +542,8 @@ def _flatten_dict(
             # nested fields.
             key = key.replace("\\", "\\\\").replace(".", "\\.")
 
-        if isinstance(value, str):
-            result[".".join(prefix + [key])] = value.lower()
+        if isinstance(value, (bool, str)) or type(value) is int or value is None:
+            result[".".join(prefix + [key])] = value
         elif isinstance(value, Mapping):
             # do not set `room_version` due to recursion considerations below
             _flatten_dict(
diff --git a/synapse/types/__init__.py b/synapse/types/__init__.py
index f82d1cfc29..52e366c8ae 100644
--- a/synapse/types/__init__.py
+++ b/synapse/types/__init__.py
@@ -69,6 +69,8 @@ StateMap = Mapping[StateKey, T]
 MutableStateMap = MutableMapping[StateKey, T]
 
 # JSON types. These could be made stronger, but will do for now.
+# A "simple" (canonical) JSON value.
+SimpleJsonValue = Optional[Union[str, int, bool]]
 # A JSON-serialisable dict.
 JsonDict = Dict[str, Any]
 # A JSON-serialisable mapping; roughly speaking an immutable JSONDict.