split state_accessor

Signed-off-by: Jason Volk <jason@zemos.net>

src/service/rooms/state_accessor/server_can.rs

@@ -0,0 +1,73 @@
+use conduwuit::{error, implement, utils::stream::ReadyExt};
+use futures::StreamExt;
+use ruma::{
+	events::{
+		room::history_visibility::{HistoryVisibility, RoomHistoryVisibilityEventContent},
+		StateEventType,
+	},
+	EventId, RoomId, ServerName,
+};
+
+/// Whether a server is allowed to see an event through federation, based on
+/// the room's history_visibility at that event's state.
+#[implement(super::Service)]
+#[tracing::instrument(skip_all, level = "trace")]
+pub async fn server_can_see_event(
+	&self,
+	origin: &ServerName,
+	room_id: &RoomId,
+	event_id: &EventId,
+) -> bool {
+	let Ok(shortstatehash) = self.pdu_shortstatehash(event_id).await else {
+		return true;
+	};
+
+	if let Some(visibility) = self
+		.server_visibility_cache
+		.lock()
+		.expect("locked")
+		.get_mut(&(origin.to_owned(), shortstatehash))
+	{
+		return *visibility;
+	}
+
+	let history_visibility = self
+		.state_get_content(shortstatehash, &StateEventType::RoomHistoryVisibility, "")
+		.await
+		.map_or(HistoryVisibility::Shared, |c: RoomHistoryVisibilityEventContent| {
+			c.history_visibility
+		});
+
+	let current_server_members = self
+		.services
+		.state_cache
+		.room_members(room_id)
+		.ready_filter(|member| member.server_name() == origin);
+
+	let visibility = match history_visibility {
+		| HistoryVisibility::WorldReadable | HistoryVisibility::Shared => true,
+		| HistoryVisibility::Invited => {
+			// Allow if any member on requesting server was AT LEAST invited, else deny
+			current_server_members
+				.any(|member| self.user_was_invited(shortstatehash, member))
+				.await
+		},
+		| HistoryVisibility::Joined => {
+			// Allow if any member on requested server was joined, else deny
+			current_server_members
+				.any(|member| self.user_was_joined(shortstatehash, member))
+				.await
+		},
+		| _ => {
+			error!("Unknown history visibility {history_visibility}");
+			false
+		},
+	};
+
+	self.server_visibility_cache
+		.lock()
+		.expect("locked")
+		.insert((origin.to_owned(), shortstatehash), visibility);
+
+	visibility
+}