cat_dev/fsemul/filesystem/

nus_fuse.rs

//! A "NUS" fuse like filesystem.
//!
//! The goal of this provider is meant to be a fuse like filesystem for
//! reading contents from an arbitrary "NUS" endpoint. The goal is to provide
//! the necessary data to PCFS without having to download ALL the content from
//! the NUS.
//!
//! We can answer many of the requests from PCFS with just the TMD, CETK,
//! FST, and some of the xml files. All in all this is significantly less data
//! and is pretty reasonable to store. From there we can download the files as
//! they are actually needed.

use crate::{
	errors::{CatBridgeError, FSError, NetworkError},
	fsemul::errors::FSEmulAPIError,
};
use bytes::{Bytes, BytesMut};
use fnv::{FnvHashSet, FnvHasher};
use reqwest::{Client, ClientBuilder, Url};
use sachet::{
	common::{CafeContentFileInformation, CafeContentFilesystemTree},
	content::decrypt,
	title::{
		TitleID,
		key_generation::title_key_guesses,
		metadata::{TitleMetadata, contents::ContentRecord},
		ticket::Ticket,
	},
};
use std::{
	hash::{Hash, Hasher},
	path::{Path, PathBuf},
};
use tracing::{debug, error, info, warn};
use valuable::{Fields, NamedField, NamedValues, StructDef, Structable, Valuable, Value, Visit};

/// The NUS Fuse filesystem that downloads from NUS, and caches to the
/// filesystem.
#[derive(Clone, Debug)]
pub struct NUSFuse {
	/// The Base NUS URL.
	///
	/// Should normally be: `https://<hostname>/ccs/download/`.
	base_url: Url,
	/// Our HTTP Client we use to contact the remote NUS server.
	client: Client,
	/// The 'hash' of the NUS URL. To cache our content from one nus specifically
	/// without colliding.
	nus_hash: String,
	/// The root directory we store titles, and cached content.
	root_directory: PathBuf,
	/// The list of title ids to fetch from NUS FUSE.
	title_ids: FnvHashSet<TitleID>,
}

impl NUSFuse {
	/// Create a new NUS FUSE filesystem.
	///
	/// ## Errors
	///
	/// If we cannot create a new HTTP client, or parse the base NUS URL.
	pub fn new(
		nus_url: &str,
		root_directory: PathBuf,
		title_ids: FnvHashSet<TitleID>,
	) -> Result<Self, FSEmulAPIError> {
		let client = ClientBuilder::new()
			.user_agent(concat!(
				env!("CARGO_PKG_NAME"),
				"/",
				env!("CARGO_PKG_VERSION"),
			))
			.brotli(true)
			.deflate(true)
			.gzip(true)
			.zstd(true)
			.build()?;
		let base_url = Url::parse(nus_url)?;
		let nus_hash = {
			let mut hasher = FnvHasher::with_key(0x69420);
			nus_url.hash(&mut hasher);
			format!("{:016x}", hasher.finish())
		};

		Ok(Self {
			base_url,
			client,
			nus_hash,
			root_directory,
			title_ids,
		})
	}

	/// Get a list of group ids in a sorted fashion.
	#[must_use]
	pub fn get_sorted_group_ids(&self) -> Vec<u32> {
		let mut group_ids = Vec::new();
		for title in &self.title_ids {
			if !group_ids.contains(&title.group_id()) {
				group_ids.push(title.group_id());
			}
		}
		group_ids.sort_by(|a, b| format!("{a:08x}").cmp(&format!("{b:08x}")));
		group_ids
	}

	/// Get a list of title ids within a group sorted.
	#[must_use]
	pub fn get_sorted_tids_in_group(&self, group_id: u32) -> Vec<u32> {
		let mut tids = Vec::new();
		for title in &self.title_ids {
			if title.group_id() == group_id && !tids.contains(&title.title_id()) {
				tids.push(title.title_id());
			}
		}
		tids.sort_by(|a, b| format!("{a:08x}").cmp(&format!("{b:08x}")));
		tids
	}

	/// Get all the files that are in a particular folder.
	pub async fn get_files_in_folder(
		&self,
		tid: TitleID,
		folder_relative_to_nus: &Path,
		is_code: bool,
	) -> Vec<(PathBuf, Option<CafeContentFileInformation>)> {
		let mut nus_title_path = self.root_directory.clone();
		nus_title_path.push(format!("{:08x}", tid.group_id()));
		nus_title_path.push(format!("{:08x}", tid.title_id()));
		nus_title_path.push(".nus");
		nus_title_path.push(&self.nus_hash);

		let Ok((tmd, tmd_raw)) = self.get_tmd(&nus_title_path, tid).await else {
			return Vec::with_capacity(0);
		};
		let Ok((fst, fst_raw)) = self.get_fst(&nus_title_path, tid, &tmd).await else {
			return Vec::with_capacity(0);
		};

		let mut saw_fst = false;
		let mut saw_preload = false;
		let mut saw_tmd = false;

		let mut items = Vec::new();
		for (relative_path, file_data) in fst.paths() {
			let Ok(leftover_path) = relative_path.strip_prefix(folder_relative_to_nus) else {
				continue;
			};
			// We only want to list things _in_ this directory straight up.
			if leftover_path.components().count() != 1 {
				continue;
			}

			if leftover_path.to_string_lossy() == "title.fst" {
				saw_fst = true;
			}
			if leftover_path.to_string_lossy() == "title.tmd" {
				saw_tmd = true;
			}
			if leftover_path.to_string_lossy() == "preload.txt" {
				saw_preload = true;
			}

			items.push((leftover_path.to_path_buf(), *file_data));
		}

		if is_code {
			if !saw_fst {
				items.push((
					PathBuf::from("title.fst"),
					Some(CafeContentFileInformation::new(
						u16::MAX,
						u32::try_from(fst_raw.len()).unwrap_or(u32::MAX),
						u64::MAX - 1,
					)),
				));
			}
			if !saw_preload {
				items.push((
					PathBuf::from("preload.txt"),
					Some(CafeContentFileInformation::new(u16::MAX, 0, u64::MAX - 2)),
				));
			}
			if !saw_tmd {
				items.push((
					PathBuf::from("title.tmd"),
					Some(CafeContentFileInformation::new(
						u16::MAX,
						u32::try_from(tmd_raw.len()).unwrap_or(u32::MAX),
						u64::MAX,
					)),
				));
			}
		}

		items
	}

	/// Check if a particular file exists on this particular NUS FUSE filesystem.
	#[must_use]
	pub async fn exists(
		&self,
		tid: TitleID,
		path_in_title: &Path,
	) -> Option<Option<CafeContentFileInformation>> {
		// This is not a title id that we have on NUS.
		if !self.title_ids.contains(&tid) {
			debug!(
				"NUS queried for unknown title: {:016x}, not serving.",
				tid.full()
			);
			return None;
		}
		let mut nus_title_path = self.root_directory.clone();
		nus_title_path.push(format!("{:08x}", tid.group_id()));
		nus_title_path.push(format!("{:08x}", tid.title_id()));
		nus_title_path.push(".nus");
		nus_title_path.push(&self.nus_hash);
		if !nus_title_path.exists()
			&& let Err(cause) = tokio::fs::create_dir_all(&nus_title_path).await
		{
			error!(
				?cause,
				title = format!("{:016x}", tid.full()),
				"Failed to create NUS cache directory for title, cannot download from NUS!",
			);

			return None;
		}

		let (tmd, tmd_raw) = match self.get_tmd(&nus_title_path, tid).await {
			Ok(t) => t,
			Err(cause) => {
				warn!(
					?cause,
					lisa.force_combine_fields = true,
					title = format!("{:016x}", tid.full()),
					"Failed to get TMD for title, will not be processing.",
				);
				return None;
			}
		};
		let (fst, fst_raw) = match self.get_fst(&nus_title_path, tid, &tmd).await {
			Ok(f) => f,
			Err(cause) => {
				warn!(
					?cause,
					lisa.force_combine_fields = true,
					title = format!("{:016x}", tid.full()),
					"Failed to get FST for title, will not be processing.",
				);
				return None;
			}
		};
		for (key, file_info) in fst.paths() {
			if key == path_in_title {
				return Some(*file_info);
			}
		}

		if path_in_title.to_string_lossy().replace('\\', "/") == "code/title.tmd" {
			return Some(Some(CafeContentFileInformation::new(
				u16::MAX,
				u32::try_from(tmd_raw.len()).unwrap_or(u32::MAX),
				u64::MAX,
			)));
		}
		if path_in_title.to_string_lossy().replace('\\', "/") == "code/title.fst" {
			return Some(Some(CafeContentFileInformation::new(
				u16::MAX,
				u32::try_from(fst_raw.len()).unwrap_or(u32::MAX),
				u64::MAX - 1,
			)));
		}
		if path_in_title.to_string_lossy().replace('\\', "/") == "code/preload.txt" {
			return Some(Some(CafeContentFileInformation::new(
				u16::MAX,
				0,
				u64::MAX - 2,
			)));
		}

		None
	}

	/// Attempt to download a particular file information into an actual path on
	/// disk, so it can be operated on locally.
	///
	/// ## Errors
	///
	/// If we cannot download the file from NUS, cannot decrypt the file from NUS,
	/// or write the file back to disk.
	pub async fn download_to(
		&self,
		disk_path: &Path,
		title_id: TitleID,
		file_info: CafeContentFileInformation,
	) -> Result<(), CatBridgeError> {
		info!(
			lisa.force_combine_fields = true,
			file.path = %disk_path.display(),
			title_id = format!("{:016x}", title_id.full()),
			"Downloading File To Disk From NUS!",
		);
		let mut nus_title_path = self.root_directory.clone();
		nus_title_path.push(format!("{:08x}", title_id.group_id()));
		nus_title_path.push(format!("{:08x}", title_id.title_id()));
		nus_title_path.push(".nus");
		nus_title_path.push(&self.nus_hash);
		if !nus_title_path.exists() {
			tokio::fs::create_dir_all(&nus_title_path)
				.await
				.map_err(FSError::IO)?;
		}
		if let Some(disk_dir) = disk_path.parent()
			&& !disk_dir.exists()
		{
			tokio::fs::create_dir_all(&disk_dir)
				.await
				.map_err(FSError::IO)?;
		}

		let (tmd, tmd_raw) = self.get_tmd(&nus_title_path, title_id).await?;

		// Special markers, is a file that needs to exist but isn't in the archive itself.
		//
		// TODO(mythra): fix all of this, this is so hacky, and bad.
		if file_info.content_idx() == u16::MAX && file_info.file_offset() == u64::MAX {
			tokio::fs::write(disk_path, &tmd_raw)
				.await
				.map_err(FSError::IO)?;
		} else if file_info.content_idx() == u16::MAX && file_info.file_offset() == u64::MAX - 1 {
			let (_, fst_raw) = self.get_fst(&nus_title_path, title_id, &tmd).await?;
			tokio::fs::write(disk_path, &fst_raw)
				.await
				.map_err(FSError::IO)?;
		} else if file_info.content_idx() == u16::MAX && file_info.file_offset() == u64::MAX - 2 {
			tokio::fs::File::create(disk_path)
				.await
				.map_err(FSError::IO)?;
		} else {
			let record = tmd
				.contents()
				.get(usize::from(file_info.content_idx()))
				.ok_or_else(|| {
					NetworkError::NUSInvalidContentID(title_id, file_info.content_idx())
				})?;
			let decrypted_content = self
				.get_and_decrypt_file(&nus_title_path, title_id, record, &file_info)
				.await?;
			tokio::fs::write(disk_path, &decrypted_content)
				.await
				.map_err(FSError::IO)?;
		}

		Ok(())
	}

	/// Fetch the TMD or read an already cached one.
	///
	/// This will return none if we cannot parse an already existing TMD, or cannot
	/// fetch a new one. This function will also cache our file to disk, so we never need
	/// to fetch from this NUS again.
	async fn get_tmd(
		&self,
		base_path: &Path,
		title_id: TitleID,
	) -> Result<(TitleMetadata, Bytes), CatBridgeError> {
		let mut tmd_path = PathBuf::from(base_path);
		tmd_path.push("tmd");

		if tmd_path.exists() {
			match tokio::fs::read(&tmd_path).await {
				Ok(data) => {
					let d_as_bytes = Bytes::from(data);
					match TitleMetadata::try_from(d_as_bytes.clone()) {
						Ok(tmd) => {
							debug!(
								nus_hash = %self.nus_hash,
								title = format!("{:016x}", title_id.full()),
								"is using cached tmd for title",
							);
							return Ok((tmd, d_as_bytes));
						}
						Err(cause) => {
							warn!(
								?cause,
								lisa.force_combine_fields = true,
								nus_hash = %self.nus_hash,
								title = format!("{:016x}", title_id.full()),
								"Failed to parse existing cached TMD, will download again!",
							);
						}
					}
				}
				Err(cause) => {
					warn!(
						?cause,
						lisa.force_combine_fields = true,
						nus_hash = %self.nus_hash,
						title = format!("{:016x}", title_id.full()),
						"Failed to read existing cached TMD, will download again!",
					);
				}
			}
		}

		let mut my_url = self.base_url.clone();
		my_url.set_path(&format!("{}/{:016x}/tmd", my_url.path(), title_id.full()));
		let resulting_bytes = match self.client.get(my_url).send().await {
			Ok(resp) => {
				if !resp.status().is_success() {
					error!(
						status = %resp.status(),
						title = format!("{:016x}", title_id.full()),
						"Failed to fetch tmd for title got bad status code, will not return TMD",
					);
					return Err(NetworkError::HTTPStatusCode(
						resp.status(),
						resp.bytes().await.ok(),
					)
					.into());
				}

				match resp.bytes().await {
					Ok(success) => success,
					Err(cause) => {
						error!(
							?cause,
							title = format!("{:016x}", title_id.full()),
							"Failed to read TMD response from successful NUS server!",
						);
						return Err(cause.into());
					}
				}
			}
			Err(cause) => {
				error!(
					?cause,
					title = format!("{:016x}", title_id.full()),
					"Failed to make TMD request to NUS server!",
				);
				return Err(cause.into());
			}
		};

		let tmd = match TitleMetadata::try_from(resulting_bytes.clone()) {
			Ok(t) => t,
			Err(cause) => {
				error!(
					?cause,
					title = format!("{:016x}", title_id.full()),
					"NUS responded with invalid TMD, will not use or cache!",
				);
				return Err(NetworkError::NUS(cause.into()).into());
			}
		};
		if let Err(cause) = tokio::fs::write(&tmd_path, &resulting_bytes).await {
			warn!(
				?cause,
				lisa.force_combine_fields = true,
				path = %tmd_path.display(),
				"Failed to write TMD to disk! Will need to download again...",
			);
		}

		Ok((tmd, resulting_bytes))
	}

	/// Get the filesystem tree for this particular NUS package.
	///
	/// This will return none, when the title does not have a FST Record, or we
	/// cannot download, decrypt, and prase the filesystem tree.
	async fn get_fst(
		&self,
		base_path: &Path,
		title_id: TitleID,
		tmd: &TitleMetadata,
	) -> Result<(CafeContentFilesystemTree, Bytes), CatBridgeError> {
		let Some(fst_record) = tmd.fst_record() else {
			error!(
				title = format!("{:016x}", title_id.full()),
				"Title does not contain a FST Record, cannot be served!",
			);
			return Err(NetworkError::NUSMissingFST(title_id).into());
		};

		let mut fst_path = PathBuf::from(base_path);
		fst_path.push("fst");
		if fst_path.exists() {
			match tokio::fs::read(&fst_path).await {
				Ok(data) => {
					let d_as_bytes = Bytes::from(data);
					match CafeContentFilesystemTree::try_from(d_as_bytes.clone()) {
						Ok(t) => return Ok((t, d_as_bytes)),
						Err(cause) => {
							warn!(
								?cause,
								lisa.force_combine_fields = true,
								nus_hash = %self.nus_hash,
								title = format!("{:016x}", title_id.full()),
								"Failed to parse existing fst, will download again!",
							);
						}
					}
				}
				Err(cause) => {
					warn!(
						?cause,
						lisa.force_combine_fields = true,
						nus_hash = %self.nus_hash,
						title = format!("{:016x}", title_id.full()),
						"Failed to read existing fst, will download again!",
					);
				}
			}
		}

		let possible_fst_contents = self
			.possible_decrypt_contents(base_path, title_id, fst_record)
			.await?;

		let mut last_error = CatBridgeError::FS(FSError::IO(std::io::Error::other(
			"zero title keys could be guessed.",
		)));
		for (content_possiblity, key) in possible_fst_contents {
			match CafeContentFilesystemTree::try_from(content_possiblity.clone()) {
				Ok(content) => {
					let mut tkeys_path = PathBuf::from(base_path);
					tkeys_path.push("possible-title-keys");
					tokio::fs::write(&tkeys_path, key)
						.await
						.map_err(FSError::IO)?;
					tokio::fs::write(&fst_path, &content_possiblity)
						.await
						.map_err(FSError::IO)?;

					return Ok((content, content_possiblity));
				}
				Err(cause) => {
					last_error = NetworkError::NUS(cause).into();
				}
			}
		}
		Err(last_error)
	}

	/// Attempt to get, and decrypt the content given a particular content id.
	///
	/// This will return none if we cannot fetch the content file, or decrypt it
	/// in anyway. Otherwise it will return all possible contents.
	async fn get_and_decrypt_file(
		&self,
		base_path: &Path,
		title_id: TitleID,
		record: &ContentRecord,
		file_info: &CafeContentFileInformation,
	) -> Result<Bytes, CatBridgeError> {
		let content_id = record.id();
		let encrypted_content = self
			.get_encrypted_content_id(base_path, title_id, content_id)
			.await?;

		let possible_title_keys = self.get_possible_title_keys(base_path, title_id).await;
		let mut decrypted: Option<Bytes> = None;
		for key in possible_title_keys {
			if let Ok(copied) = decrypt(encrypted_content.clone(), key, Some(file_info), record) {
				decrypted = Some(copied);
				break;
			}
		}

		let Some(final_bytes) = decrypted else {
			warn!(
				content_id = format!("{content_id:08x}"),
				lisa.force_combine_fields = true,
				nus_hash = %self.nus_hash,
				title = format!("{:016x}", title_id.full()),
				"Failed to decrypt content for title ID! will not load file!",
			);
			return Err(NetworkError::NUSNoTitleKey(title_id).into());
		};

		Ok(final_bytes)
	}

	/// Attempt to get all possible decryptions for a piece of content.
	///
	/// This will return none if we cannot fetch the content file, or decrypt it
	/// in anyway. Otherwise it will return all possible contents.
	async fn possible_decrypt_contents(
		&self,
		base_path: &Path,
		title_id: TitleID,
		record: &ContentRecord,
	) -> Result<Vec<(Bytes, [u8; 16])>, CatBridgeError> {
		let content_id = record.id();
		let encrypted_content = self
			.get_encrypted_content_id(base_path, title_id, content_id)
			.await?;
		let possible_title_keys = self.get_possible_title_keys(base_path, title_id).await;

		let mut decrypted = Vec::new();
		for key in possible_title_keys {
			if let Ok(copied) = decrypt(encrypted_content.clone(), key, None, record) {
				decrypted.push((copied, key));
			}
		}

		Ok(decrypted)
	}

	/// Attempt to get, and decrypt the content given a particular content id.
	///
	/// This will return none if we cannot fetch the content file.
	async fn get_encrypted_content_id(
		&self,
		base_path: &Path,
		title_id: TitleID,
		content_id: u32,
	) -> Result<Bytes, CatBridgeError> {
		let content_id_fetchable = format!("{content_id:08x}");
		let mut encrypted_path = PathBuf::from(base_path);
		encrypted_path.push("encrypted");
		tokio::fs::create_dir_all(&encrypted_path)
			.await
			.map_err(FSError::IO)?;
		encrypted_path.push(format!("{content_id_fetchable}.app"));

		if encrypted_path.exists() {
			match tokio::fs::read(&encrypted_path).await {
				Ok(data) => {
					debug!(
						content_id = format!("{content_id:08x}"),
						nus_hash = %self.nus_hash,
						title = format!("{:016x}", title_id.full()),
						"Using cached encrypted app.",
					);

					return Ok(Bytes::from(data));
				}
				Err(cause) => {
					warn!(
						?cause,
						content_id = format!("{content_id:08x}"),
						lisa.force_combine_fields = true,
						nus_hash = %self.nus_hash,
						title = format!("{:016x}", title_id.full()),
						"Failed to read existing encrypted app, will download again!",
					);
				}
			}
		}

		let mut my_url = self.base_url.clone();
		my_url.set_path(&format!(
			"{}/{:016x}/{content_id_fetchable}",
			my_url.path(),
			title_id.full()
		));
		let resulting_bytes = match self.client.get(my_url).send().await {
			Ok(resp) => {
				if !resp.status().is_success() {
					warn!(
						content_id = format!("{content_id:08x}"),
						status = %resp.status(),
						title = format!("{:016x}", title_id.full()),
						"Failed to fetch content for title got bad status code, will not return encrypted app",
					);
					return Err(NetworkError::HTTPStatusCode(
						resp.status(),
						resp.bytes().await.ok(),
					)
					.into());
				}

				match resp.bytes().await {
					Ok(success) => success,
					Err(cause) => {
						warn!(
							?cause,
							content_id = format!("{content_id:08x}"),
							title = format!("{:016x}", title_id.full()),
							"Failed to read content for title response from successful NUS server!",
						);
						return Err(cause.into());
					}
				}
			}
			Err(cause) => {
				warn!(
					?cause,
					content_id = format!("{content_id:08x}"),
					title = format!("{:016x}", title_id.full()),
					"Failed to read content for title request to NUS server!",
				);
				return Err(cause.into());
			}
		};

		if let Err(cause) = tokio::fs::write(&encrypted_path, &resulting_bytes).await {
			warn!(
				?cause,
				content_id = format!("{content_id:08x}"),
				lisa.force_combine_fields = true,
				path = %encrypted_path.display(),
				"Failed to write encrypted app file to disk! Will need to fetch again.",
			);
		}
		Ok(resulting_bytes)
	}

	/// Get a list of all the possible title keys.
	///
	/// *NOTE(anyone): These title keys are not guaranteed to be correct, or have any.*
	async fn get_possible_title_keys(
		&self,
		base_path: &Path,
		title_id: TitleID,
	) -> Vec<[u8; 0x10]> {
		let mut tkeys_path = PathBuf::from(base_path);
		tkeys_path.push("possible-title-keys");

		if tkeys_path.exists() {
			match tokio::fs::read(&tkeys_path).await {
				Ok(data) => {
					debug!(
						nus_hash = %self.nus_hash,
						title = format!("{:016x}", title_id.full()),
						"Using cached title keys",
					);

					return data
						.chunks(0x10)
						.filter_map(|c| {
							if c.len() == 0x10 {
								Some([
									c[0], c[1], c[2], c[3], c[4], c[5], c[6], c[7], c[8], c[9],
									c[10], c[11], c[12], c[13], c[14], c[15],
								])
							} else {
								None
							}
						})
						.collect::<Vec<_>>();
				}
				Err(cause) => {
					warn!(
						?cause,
						lisa.force_combine_fields = true,
						nus_hash = %self.nus_hash,
						title = format!("{:016x}", title_id.full()),
						"Failed to read existing cached title keys, will generate again!",
					);
				}
			}
		}

		let title_keys: Vec<[u8; 0x10]> =
			if let Ok(tik) = self.fetch_ticket(base_path, title_id).await {
				if let Ok(title_key) = tik.v0_header().title_key() {
					vec![title_key]
				} else {
					title_key_guesses(title_id)
				}
			} else {
				title_key_guesses(title_id)
			};

		let mut serialized = BytesMut::with_capacity(title_keys.len() * 0x10);
		for key in &title_keys {
			serialized.extend(key);
		}
		if let Err(cause) = tokio::fs::write(&tkeys_path, &serialized.freeze()).await {
			warn!(
				?cause,
				lisa.force_combine_fields = true,
				path = %tkeys_path.display(),
				"Failed to write title-keys to disk! Will need to generate again...",
			);
		}
		title_keys
	}

	/// Attempt to fetch a ticket for a particular title.
	///
	/// *NOTE(anyone): THIS IS NOT GUARANTEED TO EXIST. EVEN FOR A VALID TITLE.*
	/// The CETK is only used for getting the title key, which we can also attempt to
	/// generate. This function is the raw wrapper around getting a ticket.
	///
	/// This will return none if:
	/// - We cannot fetch a local cache of the ticket.
	/// - We cannot download the ticket from NUS.
	/// - We cannot parse the ticket from NUS.
	async fn fetch_ticket(
		&self,
		base_path: &Path,
		title_id: TitleID,
	) -> Result<Ticket, CatBridgeError> {
		let mut ticket_path = PathBuf::from(base_path);
		ticket_path.push("title.tik");

		if ticket_path.exists() {
			match tokio::fs::read(&ticket_path).await {
				Ok(data) => match Ticket::try_from(Bytes::from(data)) {
					Ok(tik) => {
						debug!(
							nus_hash = %self.nus_hash,
							title = format!("{:016x}", title_id.full()),
							"is using cached cetk for title",
						);
						return Ok(tik);
					}
					Err(cause) => {
						warn!(
							?cause,
							lisa.force_combine_fields = true,
							nus_hash = %self.nus_hash,
							title = format!("{:016x}", title_id.full()),
							"Failed to parse existing CETK, will download again!",
						);
					}
				},
				Err(cause) => {
					warn!(
						?cause,
						lisa.force_combine_fields = true,
						nus_hash = %self.nus_hash,
						title = format!("{:016x}", title_id.full()),
						"Failed to read existing cached CETK, will download again!",
					);
				}
			}
		}

		let mut my_url = self.base_url.clone();
		my_url.set_path(&format!("{}/{:016x}/cetk", my_url.path(), title_id.full()));
		let resulting_bytes = match self.client.get(my_url).send().await {
			Ok(resp) => {
				if !resp.status().is_success() {
					warn!(
						status = %resp.status(),
						title = format!("{:016x}", title_id.full()),
						"Failed to fetch cetk for title got bad status code, will not return cetk",
					);
					return Err(NetworkError::HTTPStatusCode(
						resp.status(),
						resp.bytes().await.ok(),
					)
					.into());
				}

				match resp.bytes().await {
					Ok(success) => success,
					Err(cause) => {
						warn!(
							?cause,
							title = format!("{:016x}", title_id.full()),
							"Failed to read CETK response from successful NUS server!",
						);
						return Err(cause.into());
					}
				}
			}
			Err(cause) => {
				warn!(
					?cause,
					title = format!("{:016x}", title_id.full()),
					"Failed to make CETK request to NUS server!",
				);
				return Err(cause.into());
			}
		};

		let tik = match Ticket::try_from(resulting_bytes.clone()) {
			Ok(t) => t,
			Err(cause) => {
				warn!(
					?cause,
					title = format!("{:016x}", title_id.full()),
					"NUS responded with invalid CETK, will not use or cache!",
				);
				return Err(NetworkError::NUS(cause.into()).into());
			}
		};
		if let Err(cause) = tokio::fs::write(&ticket_path, &resulting_bytes).await {
			warn!(
				?cause,
				lisa.force_combine_fields = true,
				path = %ticket_path.display(),
				"Failed to write CETK to disk! Will need to download again...",
			);
		}
		Ok(tik)
	}
}

const NUS_FUSE_FIELDS: &[NamedField<'static>] = &[
	NamedField::new("base_url"),
	NamedField::new("client"),
	NamedField::new("nus_hash"),
	NamedField::new("root_directory"),
];

impl Structable for NUSFuse {
	fn definition(&self) -> StructDef<'_> {
		StructDef::new_static("NUSFuse", Fields::Named(NUS_FUSE_FIELDS))
	}
}

impl Valuable for NUSFuse {
	fn as_value(&self) -> Value<'_> {
		Value::Structable(self)
	}

	fn visit(&self, visitor: &mut dyn Visit) {
		visitor.visit_named_fields(&NamedValues::new(
			NUS_FUSE_FIELDS,
			&[
				Valuable::as_value(&format!("{}", self.base_url)),
				Valuable::as_value(&format!("{:?}", self.client)),
				Valuable::as_value(&self.nus_hash),
				Valuable::as_value(&format!("{}", self.root_directory.display())),
			],
		));
	}
}