Implementation for MSC3664: Pushrules for relations

changelog.d/11804.feature

@@ -0,0 +1 @@
+Implement [MSC3664](https://github.com/matrix-org/matrix-doc/pull/3664). Contributed by Nico.

rust/src/push/base_rules.rs

@@ -25,6 +25,7 @@ use crate::push::Action;
 use crate::push::Condition;
 use crate::push::EventMatchCondition;
 use crate::push::PushRule;
+use crate::push::RelatedEventMatchCondition;
 use crate::push::SetTweak;
 use crate::push::TweakValue;
 
@@ -114,6 +115,21 @@ pub const BASE_APPEND_OVERRIDE_RULES: &[PushRule] = &[
         default: true,
         default_enabled: true,
     },
+    PushRule {
+        rule_id: Cow::Borrowed("global/override/.im.nheko.msc3664.reply"),
+        priority_class: 5,
+        conditions: Cow::Borrowed(&[Condition::Known(KnownCondition::RelatedEventMatch(
+            RelatedEventMatchCondition {
+                key: Some(Cow::Borrowed("sender")),
+                pattern: None,
+                pattern_type: Some(Cow::Borrowed("user_id")),
+                rel_type: Cow::Borrowed("m.in_reply_to"),
+            },
+        ))]),
+        actions: Cow::Borrowed(&[Action::Notify, HIGHLIGHT_ACTION, SOUND_ACTION]),
+        default: true,
+        default_enabled: true,
+    },
     PushRule {
         rule_id: Cow::Borrowed("global/override/.m.rule.contains_display_name"),
         priority_class: 5,

rust/src/push/evaluator.rs

@@ -23,6 +23,7 @@ use regex::Regex;
 use super::{
     utils::{get_glob_matcher, get_localpart_from_id, GlobMatchType},
     Action, Condition, EventMatchCondition, FilteredPushRules, KnownCondition,
+    RelatedEventMatchCondition,
 };
 
 lazy_static! {
@@ -49,6 +50,13 @@ pub struct PushRuleEvaluator {
     /// The power level of the sender of the event, or None if event is an
     /// outlier.
     sender_power_level: Option<i64>,
+
+    /// The related events, indexed by relation type. Flattened in the same manner as
+    /// `flattened_keys`.
+    related_events_flattened: BTreeMap<String, BTreeMap<String, String>>,
+
+    /// If msc3664, push rules for related events, is enabled.
+    related_event_match_enabled: bool,
 }
 
 #[pymethods]
@@ -60,6 +68,8 @@ impl PushRuleEvaluator {
         room_member_count: u64,
         sender_power_level: Option<i64>,
         notification_power_levels: BTreeMap<String, i64>,
+        related_events_flattened: BTreeMap<String, BTreeMap<String, String>>,
+        related_event_match_enabled: bool,
     ) -> Result<Self, Error> {
         let body = flattened_keys
             .get("content.body")
@@ -72,6 +82,8 @@ impl PushRuleEvaluator {
             room_member_count,
             notification_power_levels,
             sender_power_level,
+            related_events_flattened,
+            related_event_match_enabled,
         })
     }
 
@@ -156,6 +168,9 @@ impl PushRuleEvaluator {
             KnownCondition::EventMatch(event_match) => {
                 self.match_event_match(event_match, user_id)?
             }
+            KnownCondition::RelatedEventMatch(event_match) => {
+                self.match_related_event_match(event_match, user_id)?
+            }
             KnownCondition::ContainsDisplayName => {
                 if let Some(dn) = display_name {
                     if !dn.is_empty() {
@@ -239,6 +254,71 @@ impl PushRuleEvaluator {
         compiled_pattern.is_match(haystack)
     }
 
+    /// Evaluates a `related_event_match` condition. (MSC3664)
+    fn match_related_event_match(
+        &self,
+        event_match: &RelatedEventMatchCondition,
+        user_id: Option<&str>,
+    ) -> Result<bool, Error> {
+        // First check if related event matching is enabled...
+        if !self.related_event_match_enabled {
+            return Ok(false);
+        }
+
+        // get the related event, fail if there is none.
+        let event = if let Some(event) = self.related_events_flattened.get(&*event_match.rel_type) {
+            event
+        } else {
+            return Ok(false);
+        };
+
+        // if we have no key, accept the event as matching, if it existed without matching any
+        // fields.
+        let key = if let Some(key) = &event_match.key {
+            key
+        } else {
+            return Ok(true);
+        };
+
+        let pattern = if let Some(pattern) = &event_match.pattern {
+            pattern
+        } else if let Some(pattern_type) = &event_match.pattern_type {
+            // The `pattern_type` can either be "user_id" or "user_localpart",
+            // either way if we don't have a `user_id` then the condition can't
+            // match.
+            let user_id = if let Some(user_id) = user_id {
+                user_id
+            } else {
+                return Ok(false);
+            };
+
+            match &**pattern_type {
+                "user_id" => user_id,
+                "user_localpart" => get_localpart_from_id(user_id)?,
+                _ => return Ok(false),
+            }
+        } else {
+            return Ok(false);
+        };
+
+        let haystack = if let Some(haystack) = event.get(&**key) {
+            haystack
+        } else {
+            return Ok(false);
+        };
+
+        // For the content.body we match against "words", but for everything
+        // else we match against the entire value.
+        let match_type = if key == "content.body" {
+            GlobMatchType::Word
+        } else {
+            GlobMatchType::Whole
+        };
+
+        let mut compiled_pattern = get_glob_matcher(pattern, match_type)?;
+        compiled_pattern.is_match(haystack)
+    }
+
     /// Match the member count against an 'is' condition
     /// The `is` condition can be things like '>2', '==3' or even just '4'.
     fn match_member_count(&self, is: &str) -> Result<bool, Error> {
@@ -267,8 +347,15 @@ impl PushRuleEvaluator {
 fn push_rule_evaluator() {
     let mut flattened_keys = BTreeMap::new();
     flattened_keys.insert("content.body".to_string(), "foo bar bob hello".to_string());
-    let evaluator =
-        PushRuleEvaluator::py_new(flattened_keys, 10, Some(0), BTreeMap::new()).unwrap();
+    let evaluator = PushRuleEvaluator::py_new(
+        flattened_keys,
+        10,
+        Some(0),
+        BTreeMap::new(),
+        BTreeMap::new(),
+        true,
+    )
+    .unwrap();
 
     let result = evaluator.run(&FilteredPushRules::default(), None, Some("bob"));
     assert_eq!(result.len(), 3);

rust/src/push/mod.rs

@@ -267,6 +267,8 @@ pub enum Condition {
 #[serde(tag = "kind")]
 pub enum KnownCondition {
     EventMatch(EventMatchCondition),
+    #[serde(rename = "im.nheko.msc3664.related_event_match")]
+    RelatedEventMatch(RelatedEventMatchCondition),
     ContainsDisplayName,
     RoomMemberCount {
         #[serde(skip_serializing_if = "Option::is_none")]
@@ -299,6 +301,18 @@ pub struct EventMatchCondition {
     pub pattern_type: Option<Cow<'static, str>>,
 }
 
+/// The body of a [`Condition::RelatedEventMatch`]
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct RelatedEventMatchCondition {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub key: Option<Cow<'static, str>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub pattern: Option<Cow<'static, str>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub pattern_type: Option<Cow<'static, str>>,
+    pub rel_type: Cow<'static, str>,
+}
+
 /// The collection of push rules for a user.
 #[derive(Debug, Clone, Default)]
 #[pyclass(frozen)]
@@ -391,15 +405,21 @@ impl PushRules {
 pub struct FilteredPushRules {
     push_rules: PushRules,
     enabled_map: BTreeMap<String, bool>,
+    msc3664_enabled: bool,
 }
 
 #[pymethods]
 impl FilteredPushRules {
     #[new]
-    pub fn py_new(push_rules: PushRules, enabled_map: BTreeMap<String, bool>) -> Self {
+    pub fn py_new(
+        push_rules: PushRules,
+        enabled_map: BTreeMap<String, bool>,
+        msc3664_enabled: bool,
+    ) -> Self {
         Self {
             push_rules,
             enabled_map,
+            msc3664_enabled,
         }
     }
 
@@ -414,13 +434,25 @@ impl FilteredPushRules {
     /// Iterates over all the rules and their enabled state, including base
     /// rules, in the order they should be executed in.
     fn iter(&self) -> impl Iterator<Item = (&PushRule, bool)> {
-        self.push_rules.iter().map(|r| {
-            let enabled = *self
-                .enabled_map
-                .get(&*r.rule_id)
-                .unwrap_or(&r.default_enabled);
-            (r, enabled)
-        })
+        self.push_rules
+            .iter()
+            .filter(|rule| {
+                // Ignore disabled experimental push rules
+                if !self.msc3664_enabled
+                    && rule.rule_id == "global/override/.im.nheko.msc3664.reply"
+                {
+                    return false;
+                }
+
+                true
+            })
+            .map(|r| {
+                let enabled = *self
+                    .enabled_map
+                    .get(&*r.rule_id)
+                    .unwrap_or(&r.default_enabled);
+                (r, enabled)
+            })
     }
 }
 
@@ -446,6 +478,17 @@ fn test_deserialize_condition() {
     let _: Condition = serde_json::from_str(json).unwrap();
 }
 
+#[test]
+fn test_deserialize_unstable_condition() {
+    let json = r#"{"kind":"im.nheko.msc3664.related_event_match","key":"content.body","pattern":"coffee","rel_type":"m.in_reply_to"}"#;
+
+    let condition: Condition = serde_json::from_str(json).unwrap();
+    assert!(matches!(
+        condition,
+        Condition::Known(KnownCondition::RelatedEventMatch(_))
+    ));
+}
+
 #[test]
 fn test_deserialize_custom_condition() {
     let json = r#"{"kind":"custom_tag"}"#;

stubs/synapse/synapse_rust/push.pyi

@@ -25,7 +25,9 @@ class PushRules:
     def rules(self) -> Collection[PushRule]: ...
 
 class FilteredPushRules:
-    def __init__(self, push_rules: PushRules, enabled_map: Dict[str, bool]): ...
+    def __init__(
+        self, push_rules: PushRules, enabled_map: Dict[str, bool], msc3664_enabled: bool
+    ): ...
     def rules(self) -> Collection[Tuple[PushRule, bool]]: ...
 
 def get_base_rule_ids() -> Collection[str]: ...
@@ -37,6 +39,8 @@ class PushRuleEvaluator:
         room_member_count: int,
         sender_power_level: Optional[int],
         notification_power_levels: Mapping[str, int],
+        related_events_flattened: Mapping[str, Mapping[str, str]],
+        related_event_match_enabled: bool,
     ): ...
     def run(
         self,

synapse/config/experimental.py

@@ -98,6 +98,9 @@ def read_config(self, config: JsonDict, **kwargs: Any) -> None:
         # 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)
 

synapse/push/bulk_push_rule_evaluator.py

@@ -45,7 +45,6 @@
 
 logger = logging.getLogger(__name__)
 
-
 push_rules_invalidation_counter = Counter(
     "synapse_push_bulk_push_rule_evaluator_push_rules_invalidation_counter", ""
 )
@@ -107,6 +106,8 @@ def __init__(self, hs: "HomeServer"):
         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",
@@ -225,6 +226,34 @@ async def action_for_event_by_user(
             sender_power_level,
         ) = await self._get_power_levels_and_sender_level(event, context)
 
+        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")
+            )
+            if reply_event_id is not None and (
+                relation_type != "m.thread"
+                or not event.content.get("m.relates_to", {}).get(
+                    "is_falling_back", False
+                )
+            ):
+                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)
+
         # Find the event's thread ID.
         relation = relation_from_event(event)
         # If the event does not have a relation, then it cannot have a thread ID.
@@ -250,6 +279,8 @@ async def action_for_event_by_user(
             room_member_count,
             sender_power_level,
             notification_levels,
+            related_events,
+            self._related_event_match_enabled,
         )
 
         users = rules_by_user.keys()

synapse/rest/client/capabilities.py

@@ -77,6 +77,11 @@ async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
                 "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