feat: MSC4297, State Resolution v2.1

Cargo.lock

@@ -2521,7 +2521,7 @@ dependencies = [
 [[package]]
 name = "ruma"
 version = "0.12.6"
-source = "git+https://github.com/ruma/ruma.git#796cc9f3aacb7e69f6ec3a0d5c2ba900c3e65910"
+source = "git+https://github.com/ruma/ruma.git#547efbf24831066ae3199dc51b93f6b3a30ea8e7"
 dependencies = [
  "assign",
  "js_int",
@@ -2540,7 +2540,7 @@ dependencies = [
 [[package]]
 name = "ruma-appservice-api"
 version = "0.12.2"
-source = "git+https://github.com/ruma/ruma.git#796cc9f3aacb7e69f6ec3a0d5c2ba900c3e65910"
+source = "git+https://github.com/ruma/ruma.git#547efbf24831066ae3199dc51b93f6b3a30ea8e7"
 dependencies = [
  "js_int",
  "ruma-common",
@@ -2552,7 +2552,7 @@ dependencies = [
 [[package]]
 name = "ruma-client-api"
 version = "0.20.4"
-source = "git+https://github.com/ruma/ruma.git#796cc9f3aacb7e69f6ec3a0d5c2ba900c3e65910"
+source = "git+https://github.com/ruma/ruma.git#547efbf24831066ae3199dc51b93f6b3a30ea8e7"
 dependencies = [
  "as_variant",
  "assign",
@@ -2575,7 +2575,7 @@ dependencies = [
 [[package]]
 name = "ruma-common"
 version = "0.15.4"
-source = "git+https://github.com/ruma/ruma.git#796cc9f3aacb7e69f6ec3a0d5c2ba900c3e65910"
+source = "git+https://github.com/ruma/ruma.git#547efbf24831066ae3199dc51b93f6b3a30ea8e7"
 dependencies = [
  "as_variant",
  "base64 0.22.1",
@@ -2607,7 +2607,7 @@ dependencies = [
 [[package]]
 name = "ruma-events"
 version = "0.30.5"
-source = "git+https://github.com/ruma/ruma.git#796cc9f3aacb7e69f6ec3a0d5c2ba900c3e65910"
+source = "git+https://github.com/ruma/ruma.git#547efbf24831066ae3199dc51b93f6b3a30ea8e7"
 dependencies = [
  "as_variant",
  "indexmap 2.9.0",
@@ -2631,7 +2631,7 @@ dependencies = [
 [[package]]
 name = "ruma-federation-api"
 version = "0.11.2"
-source = "git+https://github.com/ruma/ruma.git#796cc9f3aacb7e69f6ec3a0d5c2ba900c3e65910"
+source = "git+https://github.com/ruma/ruma.git#547efbf24831066ae3199dc51b93f6b3a30ea8e7"
 dependencies = [
  "bytes",
  "headers",
@@ -2653,7 +2653,7 @@ dependencies = [
 [[package]]
 name = "ruma-identifiers-validation"
 version = "0.10.1"
-source = "git+https://github.com/ruma/ruma.git#796cc9f3aacb7e69f6ec3a0d5c2ba900c3e65910"
+source = "git+https://github.com/ruma/ruma.git#547efbf24831066ae3199dc51b93f6b3a30ea8e7"
 dependencies = [
  "js_int",
  "thiserror 2.0.12",
@@ -2662,7 +2662,7 @@ dependencies = [
 [[package]]
 name = "ruma-macros"
 version = "0.15.2"
-source = "git+https://github.com/ruma/ruma.git#796cc9f3aacb7e69f6ec3a0d5c2ba900c3e65910"
+source = "git+https://github.com/ruma/ruma.git#547efbf24831066ae3199dc51b93f6b3a30ea8e7"
 dependencies = [
  "cfg-if",
  "proc-macro-crate",
@@ -2677,7 +2677,7 @@ dependencies = [
 [[package]]
 name = "ruma-push-gateway-api"
 version = "0.11.0"
-source = "git+https://github.com/ruma/ruma.git#796cc9f3aacb7e69f6ec3a0d5c2ba900c3e65910"
+source = "git+https://github.com/ruma/ruma.git#547efbf24831066ae3199dc51b93f6b3a30ea8e7"
 dependencies = [
  "js_int",
  "ruma-common",
@@ -2689,7 +2689,7 @@ dependencies = [
 [[package]]
 name = "ruma-signatures"
 version = "0.17.1"
-source = "git+https://github.com/ruma/ruma.git#796cc9f3aacb7e69f6ec3a0d5c2ba900c3e65910"
+source = "git+https://github.com/ruma/ruma.git#547efbf24831066ae3199dc51b93f6b3a30ea8e7"
 dependencies = [
  "base64 0.22.1",
  "ed25519-dalek",
@@ -2705,7 +2705,7 @@ dependencies = [
 [[package]]
 name = "ruma-state-res"
 version = "0.13.0"
-source = "git+https://github.com/ruma/ruma.git#796cc9f3aacb7e69f6ec3a0d5c2ba900c3e65910"
+source = "git+https://github.com/ruma/ruma.git#547efbf24831066ae3199dc51b93f6b3a30ea8e7"
 dependencies = [
  "js_int",
  "ruma-common",

src/service/rooms/auth_chain/mod.rs

@@ -5,7 +5,7 @@ use std::{
 };
 
 pub use data::Data;
-use ruma::{api::client::error::ErrorKind, EventId, RoomId};
+use ruma::{api::client::error::ErrorKind, state_res::StateMap, EventId, RoomId};
 use tracing::{debug, error, warn};
 
 use crate::{services, Error, Result};
@@ -161,4 +161,87 @@ impl Service {
 
         Ok(found)
     }
+
+    #[tracing::instrument(skip(self, conflicted_state_set))]
+    /// Fetches the conflicted state subgraph of the given events
+    pub fn get_conflicted_state_subgraph(
+        &self,
+        room_id: &RoomId,
+        conflicted_state_set: &StateMap<Vec<Arc<EventId>>>,
+    ) -> Result<HashSet<Arc<EventId>>> {
+        let conflicted_event_ids: HashSet<_> =
+            conflicted_state_set.values().flatten().cloned().collect();
+        let mut conflicted_state_subgraph = HashSet::new();
+
+        let mut stack = vec![conflicted_event_ids.iter().cloned().collect::<Vec<_>>()];
+        let mut path = Vec::new();
+
+        let mut seen_events = HashSet::new();
+
+        let next_event = |stack: &mut Vec<Vec<_>>, path: &mut Vec<_>| {
+            while stack.last().is_some_and(|s| s.is_empty()) {
+                stack.pop();
+                path.pop();
+            }
+
+            stack.last_mut().and_then(|s| s.pop())
+        };
+
+        while let Some(event_id) = next_event(&mut stack, &mut path) {
+            path.push(event_id.clone());
+
+            if conflicted_state_subgraph.contains(&event_id) {
+                // If we reach a conflicted state subgraph path, this path must also be part of
+                // the conflicted state subgraph, as we will eventually reach a conflicted event
+                // if we follow this path.
+                //
+                // We check if path > 1 here and below, as we don't consider a single conflicted
+                // event to be a path from one conflicted to another.
+                if path.len() > 1 {
+                    conflicted_state_subgraph.extend(path.iter().cloned());
+                }
+
+                // All possible paths from this event must have been traversed in the iteration
+                // that caused this event to be added to the conflicted state subgraph in the first
+                // place.
+                //
+                // We pop the path here and below as it won't be removed by `next_event`, due to us
+                // never pushing it's auth events to the stack.
+                path.pop();
+                continue;
+            }
+
+            if conflicted_event_ids.contains(&event_id) && path.len() > 1 {
+                conflicted_state_subgraph.extend(path.iter().cloned());
+            }
+
+            if seen_events.contains(&event_id) {
+                // All possible paths from this event must have been traversed in the iteration
+                // that caused this event to be added to the conflicted state subgraph in the first
+                // place.
+                path.pop();
+                continue;
+            }
+
+            if let Some(pdu) = services().rooms.timeline.get_pdu(&event_id)? {
+                if pdu.room_id().as_ref() != room_id {
+                    return Err(Error::BadRequest(
+                        ErrorKind::forbidden(),
+                        "Evil event in db",
+                    ));
+                }
+
+                stack.push(pdu.auth_events.clone());
+            } else {
+                warn!(?event_id, "Could not find pdu mentioned in auth events");
+                return Err(Error::BadDatabase(
+                    "Missing auth event for PDU stored in database",
+                ));
+            }
+
+            seen_events.insert(event_id);
+        }
+
+        Ok(conflicted_state_subgraph)
+    }
 }

src/service/rooms/event_handler/mod.rs

@@ -31,7 +31,7 @@ use ruma::{
         StateEventType, TimelineEventType,
     },
     int,
-    room_version_rules::{AuthorizationRules, RoomVersionRules},
+    room_version_rules::{AuthorizationRules, RoomVersionRules, StateResolutionV2Rules},
     state_res::{self, StateMap},
     uint, CanonicalJsonObject, CanonicalJsonValue, EventId, MilliSecondsSinceUnixEpoch,
     OwnedServerName, OwnedServerSigningKeyId, RoomId, ServerName,
@@ -709,10 +709,11 @@ impl Service {
                 let lock = services().globals.stateres_mutex.lock();
 
                 let result = state_res::resolve(
-                    &room_version_id
+                    &room_version_rules.authorization,
-                        .rules()
+                    room_version_rules
-                        .expect("Supported room version has rules")
+                        .state_res
-                        .authorization,
+                        .v2_rules()
+                        .expect("We only support room versions using state resolution v2"),
                     &fork_states,
                     auth_chain_sets,
                     |id| {
@@ -722,6 +723,13 @@ impl Service {
                         }
                         res.ok().flatten()
                     },
+                    |css| {
+                        services()
+                            .rooms
+                            .auth_chain
+                            .get_conflicted_state_subgraph(room_id, css)
+                            .ok()
+                    },
                 );
                 drop(lock);
 
@@ -961,7 +969,15 @@ impl Service {
             }
 
             let new_room_state = self
-                .resolve_state(room_id, &room_version_rules.authorization, state_after)
+                .resolve_state(
+                    room_id,
+                    &room_version_rules.authorization,
+                    room_version_rules
+                        .state_res
+                        .v2_rules()
+                        .expect("We only support room versions using state resolution v2"),
+                    state_after,
+                )
                 .await?;
 
             // Set the new room state to the resolved state
@@ -1039,6 +1055,7 @@ impl Service {
         &self,
         room_id: &RoomId,
         auth_rules: &AuthorizationRules,
+        state_res_rules: &StateResolutionV2Rules,
         incoming_state: HashMap<u64, Arc<EventId>>,
     ) -> Result<Arc<HashSet<CompressedStateEvent>>> {
         debug!("Loading current room state ids");
@@ -1097,8 +1114,20 @@ impl Service {
         };
 
         let lock = services().globals.stateres_mutex.lock();
-        let state = match state_res::resolve(auth_rules, &fork_states, auth_chain_sets, fetch_event)
+        let state = match state_res::resolve(
-        {
+            auth_rules,
+            state_res_rules,
+            &fork_states,
+            auth_chain_sets,
+            fetch_event,
+            |css| {
+                services()
+                    .rooms
+                    .auth_chain
+                    .get_conflicted_state_subgraph(room_id, css)
+                    .ok()
+            },
+        ) {
             Ok(new_state) => new_state,
             Err(_) => {
                 return Err(Error::bad_database("State resolution failed, either an event could not be found or deserialization"));