fix: wrong soft fail check, too many events in /sync state response

src/client_server/sync.rs

@@ -246,31 +246,13 @@ async fn sync_helper(
             .current_shortstatehash(&room_id)?
             .expect("All rooms have state");
 
-        let first_pdu_before_since = db
-            .rooms
-            .pdus_until(&sender_user, &room_id, since)?
-            .next()
-            .transpose()?;
-
         let pdus_after_since = db
             .rooms
             .pdus_after(&sender_user, &room_id, since)?
             .next()
             .is_some();
 
-        let since_shortstatehash = first_pdu_before_since
+        let since_shortstatehash = db.rooms.get_token_shortstatehash(&room_id, since)?;
-            .as_ref()
-            .map(|pdu| {
-                db.rooms
-                    .pdu_shortstatehash(&pdu.1.event_id)
-                    .transpose()
-                    .ok_or_else(|| {
-                        warn!("PDU without state: {}", pdu.1.event_id);
-                        Error::bad_database("Found PDU without state")
-                    })
-            })
-            .transpose()?
-            .transpose()?;
 
         // Calculates joined_member_count, invited_member_count and heroes
         let calculate_counts = || {
@@ -359,7 +341,7 @@ async fn sync_helper(
                 true,
                 state_events,
             )
-        } else if !pdus_after_since || since_shortstatehash == Some(current_shortstatehash) {
+        } else if !pdus_after_since && since_shortstatehash == Some(current_shortstatehash) {
             // No state changes
             (Vec::new(), None, None, false, Vec::new())
         } else {
@@ -400,11 +382,6 @@ async fn sync_helper(
                 current_state_ids
                     .iter()
                     .filter(|(key, id)| since_state_ids.get(key) != Some(id))
-                    .filter(|(_, id)| {
-                        !timeline_pdus
-                            .iter()
-                            .any(|(_, timeline_pdu)| timeline_pdu.event_id == **id)
-                    })
                     .map(|(_, id)| db.rooms.get_pdu(id))
                     .filter_map(|r| r.ok().flatten())
                     .collect()
@@ -585,6 +562,9 @@ async fn sync_helper(
             );
         }
 
+        // Save the state after this sync so we can send the correct state diff next sync
+        db.rooms.associate_token_shortstatehash(&room_id, next_batch, current_shortstatehash)?;
+
         let joined_room = sync_events::JoinedRoom {
             account_data: sync_events::RoomAccountData {
                 events: db

src/database.rs

@@ -271,6 +271,7 @@ impl Database {
                 shorteventid_eventid: builder.open_tree("shorteventid_eventid")?,
                 shorteventid_shortstatehash: builder.open_tree("shorteventid_shortstatehash")?,
                 roomid_shortstatehash: builder.open_tree("roomid_shortstatehash")?,
+                roomsynctoken_shortstatehash: builder.open_tree("roomsynctoken_shortstatehash")?,
                 statehash_shortstatehash: builder.open_tree("statehash_shortstatehash")?,
 
                 eventid_outlierpdu: builder.open_tree("eventid_outlierpdu")?,

src/database/rooms.rs

@@ -69,6 +69,7 @@ pub struct Rooms {
 
     /// Remember the current state hash of a room.
     pub(super) roomid_shortstatehash: Arc<dyn Tree>,
+    pub(super) roomsynctoken_shortstatehash: Arc<dyn Tree>,
     /// Remember the state hash at events in the past.
     pub(super) shorteventid_shortstatehash: Arc<dyn Tree>,
     /// StateKey = EventType + StateKey, ShortStateKey = Count
@@ -1800,6 +1801,38 @@ impl Rooms {
         Ok(())
     }
 
+    pub fn associate_token_shortstatehash(
+        &self,
+        room_id: &RoomId,
+        token: u64,
+        shortstatehash: u64,
+    ) -> Result<()> {
+        let shortroomid = self.get_shortroomid(room_id)?.expect("room exists");
+
+        let mut key = shortroomid.to_be_bytes().to_vec();
+        key.extend_from_slice(&token.to_be_bytes());
+
+        self.roomsynctoken_shortstatehash
+            .insert(&key, &shortstatehash.to_be_bytes())
+    }
+
+    pub fn get_token_shortstatehash(&self, room_id: &RoomId, token: u64) -> Result<Option<u64>> {
+        let shortroomid = self.get_shortroomid(room_id)?.expect("room exists");
+
+        let mut key = shortroomid.to_be_bytes().to_vec();
+        key.extend_from_slice(&token.to_be_bytes());
+
+        Ok(self
+            .roomsynctoken_shortstatehash
+            .get(&key)?
+            .map(|bytes| {
+                utils::u64_from_bytes(&bytes).map_err(|_| {
+                    Error::bad_database("Invalid shortstatehash in roomsynctoken_shortstatehash")
+                })
+            })
+            .transpose()?)
+    }
+
     /// Creates a new persisted data unit and adds it to a room.
     #[tracing::instrument(skip(self, db, _mutex_lock))]
     pub fn build_and_append_pdu(

src/server_server.rs

@@ -1387,6 +1387,17 @@ async fn upgrade_outlier_to_timeline_pdu(
         .state_full_ids(current_sstatehash)
         .map_err(|_| "Failed to load room state.")?;
 
+    let auth_events = db
+        .rooms
+        .get_auth_events(
+            &room_id,
+            &incoming_pdu.kind,
+            &incoming_pdu.sender,
+            incoming_pdu.state_key.as_deref(),
+            &incoming_pdu.content,
+        )
+        .map_err(|_| "Failed to get_auth_events.".to_owned())?;
+
     if incoming_pdu.state_key.is_some() {
         let mut extremity_sstatehashes = HashMap::new();
 
@@ -1541,18 +1552,8 @@ async fn upgrade_outlier_to_timeline_pdu(
 
     extremities.insert(incoming_pdu.event_id.clone());
 
-    debug!("starting soft fail auth check");
     // 13. Check if the event passes auth based on the "current state" of the room, if not "soft fail" it
-    let auth_events = db
+    debug!("starting soft fail auth check");
-        .rooms
-        .get_auth_events(
-            &room_id,
-            &incoming_pdu.kind,
-            &incoming_pdu.sender,
-            incoming_pdu.state_key.as_deref(),
-            &incoming_pdu.content,
-        )
-        .map_err(|_| "Failed to get_auth_events.".to_owned())?;
 
     let soft_fail = !state_res::event_auth::auth_check(
         &room_version,