Implementation for MSC3664: Pushrules for relations (#11804)

4 files changed, 67 insertions, 5 deletions

diff --git a/synapse/config/experimental.py b/synapse/config/experimental.py
index 4009add01d..d9bdd66d55 100644
--- a/synapse/config/experimental.py
+++ b/synapse/config/experimental.py
@@ -98,6 +98,9 @@ class ExperimentalConfig(Config):
         # MSC3773: Thread notifications
         self.msc3773_enabled: bool = experimental.get("msc3773_enabled", False)
 
+        # MSC3664: Pushrules to match on related events
+        self.msc3664_enabled: bool = experimental.get("msc3664_enabled", False)
+
         # MSC3848: Introduce errcodes for specific event sending failures
         self.msc3848_enabled: bool = experimental.get("msc3848_enabled", False)
 
diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index d7795a9080..75b7e126ca 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -45,7 +45,6 @@ if TYPE_CHECKING:
 
 logger = logging.getLogger(__name__)
 
-
 push_rules_invalidation_counter = Counter(
     "synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter", ""
 )
@@ -107,6 +106,8 @@ class BulkPushRuleEvaluator:
         self.clock = hs.get_clock()
         self._event_auth_handler = hs.get_event_auth_handler()
 
+        self._related_event_match_enabled = self.hs.config.experimental.msc3664_enabled
+
         self.room_push_rule_cache_metrics = register_cache(
             "cache",
             "room_push_rule_cache",
@@ -218,6 +219,48 @@ class BulkPushRuleEvaluator:
 
         return pl_event.content if pl_event else {}, sender_level
 
+    async def _related_events(self, event: EventBase) -> Dict[str, Dict[str, str]]:
+        """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]] = {}
+        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")
+            if related_event_id is not None and relation_type is not None:
+                related_event = await self.store.get_event(
+                    related_event_id, allow_none=True
+                )
+                if related_event is not None:
+                    related_events[relation_type] = _flatten_dict(related_event)
+
+            reply_event_id = (
+                event.content.get("m.relates_to", {})
+                .get("m.in_reply_to", {})
+                .get("event_id")
+            )
+
+            # convert replies to pseudo relations
+            if reply_event_id is not None:
+                related_event = await self.store.get_event(
+                    reply_event_id, allow_none=True
+                )
+
+                if related_event is not None:
+                    related_events["m.in_reply_to"] = _flatten_dict(related_event)
+
+                    # indicate that this is from a fallback relation.
+                    if relation_type == "m.thread" and event.content.get(
+                        "m.relates_to", {}
+                    ).get("is_falling_back", False):
+                        related_events["m.in_reply_to"][
+                            "im.vector.is_falling_back"
+                        ] = ""
+
+        return related_events
+
     async def action_for_events_by_user(
         self, events_and_context: List[Tuple[EventBase, EventContext]]
     ) -> None:
@@ -286,6 +329,8 @@ class BulkPushRuleEvaluator:
                 # the parent is part of a thread.
                 thread_id = await self.store.get_thread_id(relation.parent_id)
 
+        related_events = await self._related_events(event)
+
         # It's possible that old room versions have non-integer power levels (floats or
         # strings). Workaround this by explicitly converting to int.
         notification_levels = power_levels.get("notifications", {})
@@ -298,6 +343,8 @@ class BulkPushRuleEvaluator:
             room_member_count,
             sender_power_level,
             notification_levels,
+            related_events,
+            self._related_event_match_enabled,
         )
 
         users = rules_by_user.keys()
diff --git a/synapse/rest/client/capabilities.py b/synapse/rest/client/capabilities.py
index 4237071c61..e84dde31b1 100644
--- a/synapse/rest/client/capabilities.py
+++ b/synapse/rest/client/capabilities.py
@@ -77,6 +77,11 @@ class CapabilitiesRestServlet(RestServlet):
                 "enabled": True,
             }
 
+        if self.config.experimental.msc3664_enabled:
+            response["capabilities"]["im.nheko.msc3664.related_event_match"] = {
+                "enabled": self.config.experimental.msc3664_enabled,
+            }
+
         return HTTPStatus.OK, response
 
 
diff --git a/synapse/storage/databases/main/push_rule.py b/synapse/storage/databases/main/push_rule.py
index 51416b2236..b6c15f29f8 100644
--- a/synapse/storage/databases/main/push_rule.py
+++ b/synapse/storage/databases/main/push_rule.py
@@ -29,6 +29,7 @@ from typing import (
 )
 
 from synapse.api.errors import StoreError
+from synapse.config.homeserver import ExperimentalConfig
 from synapse.replication.slave.storage._slaved_id_tracker import SlavedIdTracker
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.database import (
@@ -62,7 +63,9 @@ logger = logging.getLogger(__name__)
 
 
 def _load_rules(
-    rawrules: List[JsonDict], enabled_map: Dict[str, bool]
+    rawrules: List[JsonDict],
+    enabled_map: Dict[str, bool],
+    experimental_config: ExperimentalConfig,
 ) -> FilteredPushRules:
     """Take the DB rows returned from the DB and convert them into a full
     `FilteredPushRules` object.
@@ -80,7 +83,9 @@ def _load_rules(
 
     push_rules = PushRules(ruleslist)
 
-    filtered_rules = FilteredPushRules(push_rules, enabled_map)
+    filtered_rules = FilteredPushRules(
+        push_rules, enabled_map, msc3664_enabled=experimental_config.msc3664_enabled
+    )
 
     return filtered_rules
 
@@ -160,7 +165,7 @@ class PushRulesWorkerStore(
 
         enabled_map = await self.get_push_rules_enabled_for_user(user_id)
 
-        return _load_rules(rows, enabled_map)
+        return _load_rules(rows, enabled_map, self.hs.config.experimental)
 
     async def get_push_rules_enabled_for_user(self, user_id: str) -> Dict[str, bool]:
         results = await self.db_pool.simple_select_list(
@@ -219,7 +224,9 @@ class PushRulesWorkerStore(
         results: Dict[str, FilteredPushRules] = {}
 
         for user_id, rules in raw_rules.items():
-            results[user_id] = _load_rules(rules, enabled_map_by_user.get(user_id, {}))
+            results[user_id] = _load_rules(
+                rules, enabled_map_by_user.get(user_id, {}), self.hs.config.experimental
+            )
 
         return results