feat: Add support for MSC4560

src/api/client/room/mod.rs

@@ -2,11 +2,12 @@ mod aliases;
 mod create;
 mod event;
 mod initial_sync;
+mod stripped_state;
 mod summary;
 mod upgrade;
 
 pub(crate) use self::{
 	aliases::get_room_aliases_route, create::create_room_route, event::get_room_event_route,
-	initial_sync::room_initial_sync_route, summary::get_room_summary,
-	upgrade::upgrade_room_route,
+	initial_sync::room_initial_sync_route, stripped_state::get_stripped_state_route,
+	summary::get_room_summary, upgrade::upgrade_room_route,
 };

src/api/client/room/stripped_state.rs

@@ -0,0 +1,71 @@
+use axum::extract::State;
+use conduwuit::{Err, Result};
+use ruma::{
+	api::client::state::get_stripped_state, assign, events::ALLOWED_STRIPPED_STATE_EVENTS,
+};
+use service::rooms::summary::{Accessibility, RoomStrippedState};
+
+use crate::{Ruma, router::ClientIdentity};
+
+/// # `POST /_matrix/client/unstable/org.continuwuity.msc4560.stripped_state/{room_id_or_alias}` ([MSC4560])
+///
+/// Returns a room's stripped state.
+///
+/// [MSC4560]: https://github.com/matrix-org/matrix-spec-proposals/pull/4560
+#[tracing::instrument(skip_all, name = "stripped_state", level = "info")]
+pub(crate) async fn get_stripped_state_route(
+	State(services): State<crate::State>,
+	body: Ruma<get_stripped_state::unstable::Request>,
+) -> Result<get_stripped_state::unstable::Response> {
+	let user_id = body.identity.as_ref().and_then(ClientIdentity::sender_user);
+
+	if body.via.len() > get_stripped_state::unstable::MAX_VIAS {
+		return Err!(Request(TooLarge("Too many vias, please be less indecisive.")));
+	}
+
+	if let Some(forbidden_type) = body
+		.state
+		.iter()
+		.find(|event_type| !ALLOWED_STRIPPED_STATE_EVENTS.contains(event_type))
+	{
+		return Err!(Request(InvalidParam(
+			"Event type {forbidden_type} may not be requested as stripped state."
+		)));
+	}
+
+	let (room_id, _) = services
+		.rooms
+		.alias
+		.resolve_with_servers(&body.room_id_or_alias, Some(body.via.clone()))
+		.await?;
+
+	if services.rooms.metadata.is_banned(&room_id).await {
+		return Err!(Request(Forbidden("This room is banned on this homeserver.")));
+	}
+
+	match services
+		.rooms
+		.summary
+		.get_stripped_state_for_user(
+			user_id,
+			&room_id,
+			&body.via,
+			&body.state,
+			body.num_joined_members,
+		)
+		.await
+	{
+		| Accessibility::Accessible((
+			via,
+			RoomStrippedState { state, num_joined_members, .. },
+		)) => Ok(
+			assign!(get_stripped_state::unstable::Response::new(via), { state, num_joined_members }),
+		),
+		| Accessibility::Inaccessible => {
+			Err!(Request(Forbidden("You may not request this room's stripped state.")))
+		},
+		| Accessibility::NotFound => {
+			Err!(Request(NotFound("This room does not exist.")))
+		},
+	}
+}

src/api/client/room/summary.rs

@@ -13,7 +13,7 @@ pub(crate) async fn get_room_summary(
 	State(services): State<crate::State>,
 	body: Ruma<get_summary::v1::Request>,
 ) -> Result<get_summary::v1::Response> {
-	let (room_id, servers) = services
+	let (room_id, _) = services
 		.rooms
 		.alias
 		.resolve_with_servers(&body.room_id_or_alias, Some(body.via.clone()))
@@ -27,12 +27,9 @@ pub(crate) async fn get_room_summary(
 		.rooms
 		.summary
 		.get_room_summary_for_user(
-			body.identity
-				.as_ref()
-				.map(ClientIdentity::expect_sender_user)
-				.transpose()?,
+			body.identity.as_ref().and_then(ClientIdentity::sender_user),
 			&room_id,
-			&servers,
+			&body.via,
 		)
 		.await?;