continuwuity/src/api/server/event.rs

use axum::extract::State;
use conduit::{err, Err, Result};
use ruma::{api::federation::event::get_event, MilliSecondsSinceUnixEpoch, RoomId};

use crate::Ruma;

/// # `GET /_matrix/federation/v1/event/{eventId}`
///
/// Retrieves a single event from the server.
///
/// - Only works if a user of this server is currently invited or joined the
///   room
pub(crate) async fn get_event_route(
	State(services): State<crate::State>, body: Ruma<get_event::v1::Request>,
) -> Result<get_event::v1::Response> {
	let event = services
		.rooms
		.timeline
		.get_pdu_json(&body.event_id)
		.await
		.map_err(|_| err!(Request(NotFound("Event not found."))))?;

	let room_id_str = event
		.get("room_id")
		.and_then(|val| val.as_str())
		.ok_or_else(|| err!(Database("Invalid event in database.")))?;

	let room_id =
		<&RoomId>::try_from(room_id_str).map_err(|_| err!(Database("Invalid room_id in event in database.")))?;

	if !services
		.rooms
		.state_accessor
		.is_world_readable(room_id)
		.await && !services
		.rooms
		.state_cache
		.server_in_room(body.origin(), room_id)
		.await
	{
		return Err!(Request(Forbidden("Server is not in room.")));
	}

	if !services
		.rooms
		.state_accessor
		.server_can_see_event(body.origin(), room_id, &body.event_id)
		.await?
	{
		return Err!(Request(Forbidden("Server is not allowed to see event.")));
	}

	Ok(get_event::v1::Response {
		origin: services.globals.server_name().to_owned(),
		origin_server_ts: MilliSecondsSinceUnixEpoch::now(),
		pdu: services
			.sending
			.convert_to_outgoing_federation_event(event)
			.await,
	})
}