diffuse get_alias_helper into services::rooms::alias

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

src/service/rooms/alias/remote.rs

@@ -0,0 +1,71 @@
+use conduit::{debug, debug_info, debug_warn, Error, Result};
+use ruma::{
+	api::{client::error::ErrorKind, federation},
+	OwnedRoomId, OwnedServerName, RoomAliasId,
+};
+
+use crate::services;
+
+pub(super) async fn resolve(
+	room_alias: &RoomAliasId, servers: Option<&Vec<OwnedServerName>>,
+) -> Result<(OwnedRoomId, Option<Vec<OwnedServerName>>)> {
+	debug!(?room_alias, ?servers, "resolve");
+
+	let mut response = services()
+		.sending
+		.send_federation_request(
+			room_alias.server_name(),
+			federation::query::get_room_information::v1::Request {
+				room_alias: room_alias.to_owned(),
+			},
+		)
+		.await;
+
+	debug!("room alias server_name get_alias_helper response: {response:?}");
+
+	if let Err(ref e) = response {
+		debug_info!(
+			"Server {} of the original room alias failed to assist in resolving room alias: {e}",
+			room_alias.server_name()
+		);
+	}
+
+	if response.as_ref().is_ok_and(|resp| resp.servers.is_empty()) || response.as_ref().is_err() {
+		if let Some(servers) = servers {
+			for server in servers {
+				response = services()
+					.sending
+					.send_federation_request(
+						server,
+						federation::query::get_room_information::v1::Request {
+							room_alias: room_alias.to_owned(),
+						},
+					)
+					.await;
+				debug!("Got response from server {server} for room aliases: {response:?}");
+
+				if let Ok(ref response) = response {
+					if !response.servers.is_empty() {
+						break;
+					}
+					debug_warn!("Server {server} responded with room aliases, but was empty? Response: {response:?}");
+				}
+			}
+		}
+	}
+
+	if let Ok(response) = response {
+		let room_id = response.room_id;
+
+		let mut pre_servers = response.servers;
+		// since the room alis server responded, insert it into the list
+		pre_servers.push(room_alias.server_name().into());
+
+		return Ok((room_id, Some(pre_servers)));
+	}
+
+	Err(Error::BadRequest(
+		ErrorKind::NotFound,
+		"No servers could assist in resolving the room alias",
+	))
+}