Add suggested assertations to prevent potentially broken extremities

src/api/client/membership.rs

@@ -1243,6 +1243,7 @@ async fn join_room_by_id_helper_remote(
 		services.rooms.timeline.get_pdu(event_id).await.ok()
 	};
 
+	debug!("running stateres check on send_join parsed PDU");
 	let auth_check = state_res::event_auth::auth_check(
 		&state_res::RoomVersion::new(&room_version_id)?,
 		&parsed_join_pdu,

src/core/matrix/state_res/event_auth.rs

@@ -13,6 +13,7 @@ use ruma::{
 		power_levels::RoomPowerLevelsEventContent,
 		third_party_invite::RoomThirdPartyInviteEventContent,
 	},
+	EventId,
 	int,
 	serde::{Base64, Raw},
 };
@@ -21,7 +22,6 @@ use serde::{
 	de::{Error as _, IgnoredAny},
 };
 use serde_json::{from_str as from_json_str, value::RawValue as RawJsonValue};
-
 use super::{
 	Error, Event, Result, StateEventType, StateKey, TimelineEventType,
 	power_levels::{
@@ -217,8 +217,9 @@ where
 	}
 
 	/*
-	// TODO: In the past this code caused problems federating with synapse, maybe this has been
-	// resolved already. Needs testing.
+	// TODO: In the past this code was commented as it caused problems with Synapse. This is no
+	// longer the case. This needs to be implemented.
+	// See also: https://github.com/ruma/ruma/pull/2064
 	//
 	// 2. Reject if auth_events
 	// a. auth_events cannot have duplicate keys since it's a BTree
@@ -250,11 +251,33 @@ where
 
 	let room_create_event = match room_create_event {
 		| None => {
-			warn!("no m.room.create event in auth chain");
+			error!(
+				create_event = room_create_event.as_ref().map(Event::event_id).unwrap_or(<&EventId>::try_from("$unknown").unwrap()).as_str(),
+				power_levels = power_levels_event.as_ref().map(Event::event_id).unwrap_or(<&EventId>::try_from("$unknown").unwrap()).as_str(),
+				member_event = sender_member_event.as_ref().map(Event::event_id).unwrap_or(<&EventId>::try_from("$unknown").unwrap()).as_str(),
+				"no m.room.create event found for {} ({})!",
+				incoming_event.event_id().as_str(),
+				incoming_event.room_id().as_str()
+			);
 			return Ok(false);
 		},
 		| Some(e) => e,
 	};
+	// just re-check 1.2 to work around a bug
+	let Some(room_id_server_name) = incoming_event.room_id().server_name() else {
+		warn!("room ID has no servername");
+		return Ok(false);
+	};
+
+	if room_id_server_name != room_create_event.sender().server_name() {
+		warn!(
+			"servername of room ID origin ({}) does not match servername of m.room.create \
+			 sender ({})",
+			room_id_server_name,
+			room_create_event.sender().server_name()
+		);
+		return Ok(false);
+	}
 
 	// 3. If event does not have m.room.create in auth_events reject
 	if !incoming_event

src/core/matrix/state_res/mod.rs

@@ -609,7 +609,7 @@ where
 		let fetch_state = |ty: &StateEventType, key: &str| {
 			future::ready(auth_state.get(&ty.with_state_key(key)))
 		};
-
+		debug!("running auth check on {:?}", event.event_id());
 		let auth_result =
 			auth_check(room_version, &event, current_third_party.as_ref(), fetch_state).await;
 
@@ -726,8 +726,12 @@ where
 	Fut: Future<Output = Option<E>> + Send,
 	E: Event + Send + Sync,
 {
+	let mut room_id = None;
 	while let Some(sort_ev) = event {
-		debug!(event_id = sort_ev.event_id().as_str(), "mainline");
+		trace!(event_id = sort_ev.event_id().as_str(), "mainline");
+		if room_id.is_none() {
+			room_id = Some(sort_ev.room_id().to_owned());
+		}
 
 		let id = sort_ev.event_id();
 		if let Some(depth) = mainline_map.get(id) {
@@ -746,7 +750,7 @@ where
 			}
 		}
 	}
-	// Did not find a power level event so we default to zero
+	warn!("could not find a power event in the mainline map for {room_id:?}, defaulting to zero depth");
 	Ok(0)
 }
 

src/service/rooms/event_handler/handle_outlier_pdu.rs

@@ -76,7 +76,7 @@ pub(super) async fn handle_outlier_pdu<'a>(
 		// 5. Reject "due to auth events" if can't get all the auth events or some of
 		//    the auth events are also rejected "due to auth events"
 		// NOTE: Step 5 is not applied anymore because it failed too often
-		debug!("Fetching auth events");
+		debug!("Fetching auth events for {}", incoming_pdu.event_id);
 		Box::pin(self.fetch_and_handle_outliers(
 			origin,
 			&incoming_pdu.auth_events,
@@ -88,12 +88,12 @@ pub(super) async fn handle_outlier_pdu<'a>(
 
 	// 6. Reject "due to auth events" if the event doesn't pass auth based on the
 	//    auth events
-	debug!("Checking based on auth events");
+	debug!("Checking {} based on auth events", incoming_pdu.event_id);
 	// Build map of auth events
 	let mut auth_events = HashMap::with_capacity(incoming_pdu.auth_events.len());
 	for id in &incoming_pdu.auth_events {
 		let Ok(auth_event) = self.services.timeline.get_pdu(id).await else {
-			warn!("Could not find auth event {id}");
+			warn!("Could not find auth event {id} for {}", incoming_pdu.event_id);
 			continue;
 		};
 
@@ -119,10 +119,7 @@ pub(super) async fn handle_outlier_pdu<'a>(
 	}
 
 	// The original create event must be in the auth events
-	if !matches!(
-		auth_events.get(&(StateEventType::RoomCreate, String::new().into())),
-		Some(_) | None
-	) {
+	if !auth_events.contains_key(&(StateEventType::RoomCreate, String::new().into())) {
 		return Err!(Request(InvalidParam("Incoming event refers to wrong create event.")));
 	}
 
@@ -131,6 +128,7 @@ pub(super) async fn handle_outlier_pdu<'a>(
 		ready(auth_events.get(&key))
 	};
 
+	debug!("running auth check to handle outlier pdu {:?}", incoming_pdu.event_id);
 	let auth_check = state_res::event_auth::auth_check(
 		&to_room_version(&room_version_id),
 		&incoming_pdu,

src/service/rooms/event_handler/upgrade_outlier_pdu.rs

@@ -1,12 +1,6 @@
 use std::{borrow::Borrow, collections::BTreeMap, iter::once, sync::Arc, time::Instant};
 
-use conduwuit::{
-	Err, Result, debug, debug_info, err, implement,
-	matrix::{EventTypeExt, PduEvent, StateKey, state_res},
-	trace,
-	utils::stream::{BroadbandExt, ReadyExt},
-	warn,
-};
+use conduwuit::{Err, Result, debug, debug_info, err, implement, matrix::{EventTypeExt, PduEvent, StateKey, state_res}, trace, utils::stream::{BroadbandExt, ReadyExt}, warn, info};
 use futures::{FutureExt, StreamExt, future::ready};
 use ruma::{CanonicalJsonValue, RoomId, ServerName, events::StateEventType};
 
@@ -44,7 +38,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 		return Err!(Request(InvalidParam("Event has been soft failed")));
 	}
 
-	debug!("Upgrading to timeline pdu");
+	debug!("Upgrading pdu {} from outlier to timeline pdu", incoming_pdu.event_id);
 	let timer = Instant::now();
 	let room_version_id = get_room_version_id(create_event)?;
 
@@ -52,7 +46,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 	//     backwards extremities doing all the checks in this list starting at 1.
 	//     These are not timeline events.
 
-	debug!("Resolving state at event");
+	debug!("Resolving state at event {}", incoming_pdu.event_id);
 	let mut state_at_incoming_event = if incoming_pdu.prev_events.len() == 1 {
 		self.state_at_incoming_degree_one(&incoming_pdu).await?
 	} else {
@@ -70,7 +64,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 		state_at_incoming_event.expect("we always set this to some above");
 	let room_version = to_room_version(&room_version_id);
 
-	debug!("Performing auth check");
+	debug!("Performing auth check to upgrade {}", incoming_pdu.event_id);
 	// 11. Check the auth of the event passes based on the state of the event
 	let state_fetch_state = &state_at_incoming_event;
 	let state_fetch = |k: StateEventType, s: StateKey| async move {
@@ -80,6 +74,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 		self.services.timeline.get_pdu(event_id).await.ok()
 	};
 
+	debug!("running auth check on {}", incoming_pdu.event_id);
 	let auth_check = state_res::event_auth::auth_check(
 		&room_version,
 		&incoming_pdu,
@@ -93,7 +88,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 		return Err!(Request(Forbidden("Event has failed auth check with state at the event.")));
 	}
 
-	debug!("Gathering auth events");
+	debug!("Gathering auth events for {}", incoming_pdu.event_id);
 	let auth_events = self
 		.services
 		.state
@@ -111,6 +106,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 		ready(auth_events.get(&key).cloned())
 	};
 
+	debug!("running auth check on {} with claimed state auth", incoming_pdu.event_id);
 	let auth_check = state_res::event_auth::auth_check(
 		&room_version,
 		&incoming_pdu,
@@ -121,7 +117,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 	.map_err(|e| err!(Request(Forbidden("Auth check failed: {e:?}"))))?;
 
 	// Soft fail check before doing state res
-	debug!("Performing soft-fail check");
+	debug!("Performing soft-fail check on {}", incoming_pdu.event_id);
 	let soft_fail = match (auth_check, incoming_pdu.redacts_id(&room_version_id)) {
 		| (false, _) => true,
 		| (true, None) => false,
@@ -218,7 +214,8 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 	// 14. Check if the event passes auth based on the "current state" of the room,
 	//     if not soft fail it
 	if soft_fail {
-		debug!("Soft failing event");
+		info!("Soft failing event {}", incoming_pdu.event_id);
+		assert!(extremities.is_empty(), "soft_fail extremities empty");
 		let extremities = extremities.iter().map(Borrow::borrow);
 
 		self.services

src/service/rooms/timeline/mod.rs

@@ -698,6 +698,20 @@ impl Service {
 			.await
 			.saturating_add(uint!(1));
 
+		if state_key.is_none() {
+			if prev_events.is_empty() {
+				warn!("Timeline event had zero prev_events, something broke.");
+				return Err!(Request(Unknown("Timeline event had zero prev_events.")));
+			}
+			if depth.le(&uint!(2)) {
+				warn!(
+					"Had unsafe depth of {depth} in {room_id} when creating non-state event. \
+					 Bad!"
+				);
+				return Err!(Request(Unknown("Unsafe depth for non-state event.")));
+			}
+		};
+
 		let mut unsigned = unsigned.unwrap_or_default();
 
 		if let Some(state_key) = &state_key {
@@ -757,6 +771,7 @@ impl Service {
 			ready(auth_events.get(&key))
 		};
 
+		debug!("running auth check on new {} event by {} in {}", pdu.kind, pdu.sender, pdu.room_id);
 		let auth_check = state_res::auth_check(
 			&room_version,
 			&pdu,
@@ -961,8 +976,9 @@ impl Service {
 		state_lock: &'a RoomMutexGuard,
 	) -> Result<Option<RawPduId>>
 	where
-		Leaves: Iterator<Item = &'a EventId> + Send + 'a,
+		Leaves: Iterator<Item = &'a EventId> + Send + Clone + 'a,
 	{
+		assert!(new_room_leaves.clone().count() > 0, "extremities are empty");
 		// We append to state before appending the pdu, so we don't have a moment in
 		// time with the pdu without it's state. This is okay because append_pdu can't
 		// fail.
@@ -1142,7 +1158,7 @@ impl Service {
 			.boxed();
 
 		while let Some(ref backfill_server) = servers.next().await {
-			info!("Asking {backfill_server} for backfill");
+			info!("Asking {backfill_server} for backfill in {:?}", room_id.to_owned());
 			let response = self
 				.services
 				.sending
@@ -1170,7 +1186,7 @@ impl Service {
 			}
 		}
 
-		info!("No servers could backfill, but backfill was needed in room {room_id}");
+		warn!("No servers could backfill, but backfill was needed in room {room_id}");
 		Ok(())
 	}