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//! This module provides client-side functionality to add to an application.
//!
//! The main struct is [`Updater`], which provides a service to check for
//! updates at intervals, and upgrade the application. This is done by querying
//! the specified API server, and if an update is found, it will be downloaded
//! and installed, and the application will be restarted. This will only occur
//! once any critical actions that have been registered are complete.
//!
//! # Critical actions
//!
//! Critical actions are registered using the [`Updater::register_action()`]
//! method, and deregistered using the [`Updater::deregister_action()`] method.
//! When a critical action is in progress, the updater will not restart the
//! application, and will wait until all critical actions are complete before
//! doing so.
//!
//! # Status
//!
//! The [`Status`] enum is used to represent the possible statuses that the
//! updater can have. The current status can be obtained at any time, using the
//! [`Updater::status()`] method, and the status change events can be
//! subscribed to using the [`Updater::subscribe()`] method.
//!
//! # Failure
//!
//! If an error occurs when trying to update, it will be logged, and the
//! updater will stop checking for updates.
//!
// Modules
#[cfg(test)]
#[path = "tests/client.rs"]
mod tests;
// Packages
use crate::responses::{LatestVersionResponse, VersionHashResponse};
use core::{
fmt::{Display, self},
str::FromStr,
sync::atomic::{AtomicUsize, Ordering},
};
use ed25519_dalek::Signature;
use flume::{Sender, self};
use futures_util::StreamExt;
use hex;
use parking_lot::RwLock;
use reqwest::{
StatusCode,
Url,
header::{AsHeaderName, CONTENT_LENGTH, CONTENT_TYPE},
};
use rubedo::{
crypto::{Sha256Hash, VerifyingKey},
sugar::s,
};
use semver::Version;
use serde::de::DeserializeOwned;
use sha2::{Sha256, Digest};
use std::{
env::args,
error::Error,
io::Error as IoError,
os::unix::fs::PermissionsExt,
path::PathBuf,
sync::Arc,
};
use tempfile::{tempdir, TempDir};
use tokio::{
fs::{File as AsyncFile, self},
io::AsyncWriteExt,
select,
spawn,
sync::broadcast::{Receiver as Listener, Sender as Broadcaster, self},
time::{Duration, interval},
};
use tracing::{debug, error, info, warn};
#[cfg(not(test))]
use ::{
reqwest::{Client, Response},
std::{
env::current_exe,
os::unix::process::CommandExt,
process::{Command, Stdio, exit},
},
};
#[cfg(test)]
use crate::mocks::{
reqwest::{Client as HttpClient, MockClient as Client, MockResponse as Response, RequestBuilder},
std_env::mock_current_exe as current_exe,
std_process::{FakeCommand as Command, MockStdio as Stdio, mock_exit as exit},
};
// Enums
// Status
/// The possible statuses that an [`Updater`] can have.
#[derive(Clone, Debug, Eq, Hash, PartialEq)]
#[non_exhaustive]
pub enum Status {
/// Nothing interesting is currently happening — there is no active upgrade
/// underway or pending.
Idle,
/// The updater is currently checking whether there is a newer version of
/// the application available.
Checking,
/// A newer version of the application is available, and the updater is
/// currently downloading the release file.
Downloading(Version, u8),
/// A newer version of the application is available, and the updater is
/// currently installing it.
Installing(Version),
/// A newer version of the application is available, and the updater is
/// currently waiting to start the upgrade process, but is blocked from
/// doing so due to one or more critical actions being in progress.
PendingRestart(Version),
/// A newer version of the application is available, and the updater is
/// currently in the process of restarting the application to apply the
/// upgrade. No new critical actions are allowed to start.
Restarting(Version),
}
// Display
impl Display for Status {
// fmt
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", match *self {
Self::Idle => s!( "Idle"),
Self::Checking => s!( "Checking"),
Self::Installing(ref version) => format!("Installing: {version}"),
Self::Downloading(ref version, ref percent) => format!("Downloading: {version} ({percent}%)"),
Self::PendingRestart(ref version) => format!("Pending restart: {version}"),
Self::Restarting(ref version) => format!("Restarting: {version}"),
})
}
}
// UpdaterError
/// Errors that can occur when trying to update.
#[derive(Clone, Debug, Eq, PartialEq)]
#[non_exhaustive]
pub enum UpdaterError {
/// Verification of the SHA256 hash of the downloaded file against the
/// server's hash data failed.
FailedHashVerification(Version),
/// Verification of the HTTP response body against the signature header
/// using the configured public key failed.
FailedSignatureVerification(Url),
/// An HTTP error occurred, i.e. the status code returned is not `200`. No
/// other codes are expected, as this library only performs `GET` requests.
HttpError(Url, StatusCode),
/// The HTTP request to the API server failed.
HttpRequestFailed(Url, String),
/// The response from the API server could not be decoded. This could be due
/// to malformed text that is not valid UTF-8 for endpoints that return text
/// or JSON, or a truncated response.
InvalidBody(Url),
/// The response from the API server could not be parsed. This could be due
/// to invalid JSON, or the JSON not matching the expected structure.
InvalidPayload(Url),
/// The signature header from the API server could not be decoded.
InvalidSignature(Url, String),
/// The URL specified to use to make an HTTP request is invalid. The API URL
/// should be okay due to type validation, so something must have happened
/// when adding a particular endpoint to it, as the outcome is invalid.
InvalidUrl(Url, String),
/// The HTTP response body from the API server is shorter than expected.
MissingData(Url, usize, usize),
/// The HTTP response from the API server does not contain a signature
/// header.
MissingSignature(Url),
/// The HTTP response body from the API server is longer than expected.
TooMuchData(Url, usize, usize),
/// A problem was encountered when trying to create a file for the download.
UnableToCreateDownload(PathBuf, String),
/// A problem was encountered when trying to create a temporary directory.
UnableToCreateTempDir(String),
/// A problem was encountered when trying to get the metadata for the new
/// executable.
UnableToGetFileMetadata(PathBuf, String),
/// A problem was encountered when trying to move the new executable into
/// the place of the current running application.
UnableToMoveNewExe(PathBuf, String),
/// A problem was encountered when trying to obtain the path of the current
/// running application.
UnableToObtainCurrentExePath(String),
/// A problem was encountered when trying to rename the current running
/// application.
UnableToRenameCurrentExe(PathBuf, String),
/// A problem was encountered when trying to set the new executable's file
/// permissions.
UnableToSetFilePermissions(PathBuf, String),
/// A problem was encountered when trying to write to the download file.
UnableToWriteToDownload(PathBuf, String),
/// The content type of the response is not as expected.
UnexpectedContentType(Url, String, String),
}
// Display
impl Display for UpdaterError {
// fmt
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", match *self {
Self::FailedHashVerification(ref version) => format!( "Failed hash verification for downloaded version {version}"),
Self::FailedSignatureVerification(ref url) => format!( "Failed signature verification for response from {url}"),
Self::HttpError(ref url, ref status) => format!( "HTTP status code {status} received when calling {url}"),
Self::HttpRequestFailed(ref url, ref msg) => format!( "HTTP request to {url} failed: {msg}"),
Self::InvalidBody(ref url) => format!( "Invalid HTTP body received from {url}"),
Self::InvalidPayload(ref url) => format!( "Invalid payload received from {url}"),
Self::InvalidSignature(ref url, ref signature) => format!(r#"Invalid signature header "{signature}" received from {url}"#),
Self::InvalidUrl(ref base, ref endpoint) => format!( "Invalid URL specified: {base} plus {endpoint}"),
Self::MissingData(ref url, ref received, ref expected) => format!( "HTTP response body from {url} is shorter than expected: {received} < {expected}"),
Self::MissingSignature(ref url) => format!( "HTTP response from {url} does not contain a signature header"),
Self::TooMuchData(ref url, ref received, ref expected) => format!( "HTTP response body from {url} is longer than expected: {received} > {expected}"),
Self::UnableToCreateDownload(ref path, ref msg) => format!(r#"Unable to create download file "{path:?}": {msg}"#),
Self::UnableToCreateTempDir(ref msg) => format!( "Unable to create temporary directory: {msg}"),
Self::UnableToGetFileMetadata(ref path, ref msg) => format!(r#"Unable to get file metadata for the new executable "{path:?}": {msg}"#),
Self::UnableToMoveNewExe(ref path, ref msg) => format!( "Unable to move the new executable {path:?}: {msg}"),
Self::UnableToObtainCurrentExePath(ref msg) => format!( "Unable to obtain current executable path: {msg}"),
Self::UnableToRenameCurrentExe(ref path, ref msg) => format!( "Unable to rename the current executable {path:?}: {msg}"),
Self::UnableToSetFilePermissions(ref path, ref msg) => format!(r#"Unable to set file permissions for the new executable "{path:?}": {msg}"#),
Self::UnableToWriteToDownload(ref path, ref msg) => format!(r#"Unable to write to download file "{path:?}": {msg}"#),
Self::UnexpectedContentType(ref url, ref value, ref expected) => format!(r#"HTTP response from {url} had unexpected content type: "{value}", expected: "{expected}""#),
})
}
}
// Error
impl Error for UpdaterError {}
// Structs
// Config
/// The configuration options for the client.
#[cfg_attr( feature = "reasons", allow(clippy::exhaustive_structs, reason = "Provided for configuration"))]
#[cfg_attr(not(feature = "reasons"), allow(clippy::exhaustive_structs))]
#[derive(Clone, Debug)]
pub struct Config {
// Public properties
/// The current version of the application. This is reported to the server
/// when making requests such as checking for updates.
pub version: Version,
/// The URL of the API. This is used to make requests to the server, such as
/// checking for updates. It needs to be an FQDN (Fully-Qualified Domain
/// Name), and should include the protocol (e.g. `https://`), plus any base
/// path (e.g. `/api`). For example, `https://api.example.com/api/v2`.
pub api: Url,
/// The public key for the server. This is used to verify the HTTP responses
/// from the server, to ensure that they have not been tampered with. The
/// format used is Ed25519, which is a modern and secure algorithm.
pub key: VerifyingKey,
/// Whether to check for updates on startup.
pub check_on_startup: bool,
/// How often to check for updates. This is optional.
pub check_interval: Option<Duration>,
}
// Updater
/// A service to check for updates at intervals, and upgrade the application.
///
/// This struct provides a service that will query the API server at defined
/// intervals, to check for updates. If an update is found, it will be
/// downloaded and installed, and the application will be restarted.
///
#[derive(Debug)]
pub struct Updater {
// Private properties
/// A counter of critical actions that are currently active. This is used to
/// prevent the updater from stopping the application while a critical
/// action is in progress.
actions: AtomicUsize,
/// The status broadcast channel that status changes are added to. This is
/// the sender side only. Each interested party can subscribe to this
/// channel to receive status changes on a real-time basis.
broadcast: Broadcaster<Status>,
/// The configuration for the updater service.
config: Config,
/// The path to the current running executable. This is used to replace the
/// executable with the new version when upgrading. It is checked at startup
/// and stored here as a reliable reference so that the updater can use it
/// later on.
exe_path: PathBuf,
/// The HTTP client instance that is used for communicating with the API
/// server.
http_client: Client,
/// The updater queue that is used for communicating with the interval
/// timer. This is the sender side only. A queue is used so that the timer
/// can run in a separate thread, but be stopped when required.
queue: Sender<()>,
/// The current status of the updater.
status: RwLock<Status>,
}
// Updater
impl Updater {
// Constructors
// new
/// Creates a new updater service instance.
///
/// This function creates a new updater service instance, with the specified
/// configuration. As soon as the service is created, it will start checking
/// for updates.
///
/// In order to shut down nicely, [`Drop`] is implemented, and will send a
/// message to the internal queue to stop the timer.
///
/// # Parameters
///
/// * `config` - The configuration for the updater service.
///
/// # Errors
///
/// * [`UpdaterError::UnableToObtainCurrentExePath`]
///
#[cfg_attr( feature = "reasons", allow(clippy::result_large_err, reason = "Doesn't matter here"))]
#[cfg_attr(not(feature = "reasons"), allow(clippy::result_large_err))]
pub fn new(config: Config) -> Result<Arc<Self>, UpdaterError> {
// Set up updater instance
let http_client = Client::new();
let (sender, receiver) = flume::unbounded();
let (tx, mut rx) = broadcast::channel(1);
let updater = Arc::new(Self {
actions: AtomicUsize::new(0),
broadcast: tx,
config,
exe_path: current_exe().map_err(|err| UpdaterError::UnableToObtainCurrentExePath(err.to_string()))?,
http_client,
queue: sender,
status: RwLock::new(Status::Idle),
});
// Listen for status change events
// It's useful to listen for status changes, so that they can be logged.
// However, a persistent subscriber is also necessary to keep the broadcast
// channel open, as it will be closed when the last subscriber is dropped.
#[cfg_attr( feature = "reasons", allow(clippy::pattern_type_mismatch, reason = "Cannot dereference here"))]
#[cfg_attr(not(feature = "reasons"), allow(clippy::pattern_type_mismatch))]
drop(spawn(async move { loop { select! {
// Wait for data from the broadcast channel
Ok(status) = rx.recv() => {
debug!("Status changed: {status}");
}
else => break,
}}}));
// Check for updates at startup
if updater.config.check_on_startup {
let startup_updater = Arc::clone(&updater);
drop(spawn(async move {
startup_updater.check_for_updates().await;
}));
}
// Check for updates at intervals
if let Some(check_interval) = updater.config.check_interval {
let mut timer = interval(check_interval);
let mut first_tick = true;
let timer_updater = Arc::clone(&updater);
// Event-handling loop
drop(spawn(async move { loop { select!{
// Wait for timer to tick
_ = timer.tick() => {
if first_tick {
first_tick = false;
continue;
}
timer_updater.check_for_updates().await;
}
// Wait for message from queue - this is a blocking call
_ = receiver.recv_async() => {
info!("Stopping updater");
break;
}
}}}));
}
Ok(updater)
}
// Public methods
// register_action
/// Registers a critical action.
///
/// This function increments the critical actions counter, preventing the
/// application from being updated while the critical action is in progress.
///
/// It returns the *likely new value* of the counter, or [`None`] if the
/// counter overflows or if starting a new action is not permitted due to a
/// pending update. The new value is likely rather than guaranteed due to
/// the effect of concurrent updates, and therefore is the value known and
/// set at the time it was incremented, and may not be the value by the time
/// the function returns.
///
pub fn register_action(&self) -> Option<usize> {
match self.status() {
Status::Idle |
Status::Checking |
Status::Downloading(_, _) |
Status::Installing(_) => {},
Status::PendingRestart(_) |
Status::Restarting(_) => return None,
}
let value = self.actions
.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |value| { value.checked_add(1) })
.ok()?
;
Some(value.saturating_add(1))
}
// deregister_action
/// Deregisters a critical action.
///
/// This function decrements the critical actions counter, allowing the
/// application to be updated once the count reaches zero.
///
/// It returns the *likely new value* of the counter, or [`None`] if the
/// counter underflows. The new value is likely rather than guaranteed due
/// to the effect of concurrent updates, and therefore is the value known
/// and set at the time it was incremented, and may not be the value by the
/// time the function returns.
///
/// If a restart is pending, then when the critical actions counter reaches
/// zero, the restart will be triggered.
///
pub fn deregister_action(&self) -> Option<usize> {
let mut value = self.actions
.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |value| { value.checked_sub(1) })
.ok()?
;
value = value.saturating_sub(1);
if let Status::PendingRestart(version) = self.status() {
if value > 0 {
info!("Pending restart: {} critical actions in progress", self.actions.load(Ordering::SeqCst));
} else {
self.set_status(Status::Restarting(version));
info!("Restarting");
self.restart();
}
}
Some(value)
}
// is_safe_to_update
/// Checks if it is safe to update.
///
/// This function checks the critical actions counter, to see if it is safe
/// to update the application — i.e. if the counter is zero.
///
/// Note that at present this is a naive implementation that does not lock
/// the counter, and so it is possible that the counter could change between
/// the time of checking and the time of updating.
///
pub fn is_safe_to_update(&self) -> bool {
self.actions.load(Ordering::SeqCst) == 0
}
// status
/// Gets the current status of the updater.
///
/// This function returns the current status of the updater, correct at the
/// time of calling.
///
/// Note that the status may change between the time of calling and the time
/// of processing the result.
///
pub fn status(&self) -> Status {
let lock = self.status.read(); // //
(*lock).clone()
}
// set_status
/// Sets the current status of the updater.
///
/// This function changes the current status of the updater to the specified
/// value.
///
pub fn set_status(&self, status: Status) {
let mut lock = self.status.write(); // //
*lock = status.clone();
drop(lock); // //
if let Err(err) = self.broadcast.send(status) {
error!("Failed to broadcast status change: {err}");
}
}
// subscribe
/// Subscribes to the status change event broadcaster.
///
/// This function provides a receiver that is subscribed to the status
/// change event broadcaster, so that every time the status changes, it will
/// be notified.
///
/// At present this simply subscribes to all status change events, but it
/// may be enhanced in future to allow for filtering.
///
pub fn subscribe(&self) -> Listener<Status> {
self.broadcast.subscribe()
}
// Private methods
// check_for_updates
/// Checks for updates.
///
/// This function checks for updates by querying the API server. If an
/// update is found, it will be downloaded and installed, and the
/// application will be restarted.
///
async fn check_for_updates(&self) {
// Ensure no updates are already underway
if self.status() != Status::Idle {
return;
}
// Get latest version
self.set_status(Status::Checking);
info!("Checking for updates");
let (url, response) = match self.request("latest").await {
Ok(data) => data,
Err(err) => {
self.set_status(Status::Idle);
error!("Error checking for updates: {err}");
return;
},
};
let version = match self.decode_and_verify::<LatestVersionResponse>(url, response).await {
Ok(json) => json.version,
Err(err) => {
self.set_status(Status::Idle);
error!("Error checking for updates: {err}");
return;
},
};
// Compare to current version
if version <= self.config.version {
self.set_status(Status::Idle);
info!("The current version {} is the latest available", self.config.version);
return;
}
info!("New version {} available", version);
// Download update file
self.set_status(Status::Downloading(version.clone(), 0));
info!("Downloading update {version}");
let (_download_dir, update_path, file_hash) = match self.download_update(&version).await {
Ok(data) => data,
Err(err) => {
error!("Error downloading update file: {err}");
return;
},
};
info!("Update file downloaded");
// Verify update file
info!("Verifying update {version}");
if let Err(err) = self.verify_update(&version, file_hash).await {
error!("Error verifying update file: {err}");
return;
}
info!("Update file verified");
// Install update
self.set_status(Status::Installing(version.clone()));
info!("Installing update");
if let Err(err) = self.replace_executable(&update_path).await {
error!("Error installing update: {err}");
return;
}
// Restart application
if !self.is_safe_to_update() {
self.set_status(Status::PendingRestart(version.clone()));
info!("Pending restart: {} critical actions in progress", self.actions.load(Ordering::SeqCst));
return;
}
self.set_status(Status::Restarting(version.clone()));
info!("Restarting");
self.restart();
}
// download_update
/// Downloads an application update.
///
/// This function downloads an application update from the API server, in
/// the form of an executable binary, and calculates the SHA256 hash of the
/// downloaded file.
///
/// # Errors
///
/// * [`UpdaterError::MissingData`]
/// * [`UpdaterError::TooMuchData`]
/// * [`UpdaterError::UnableToCreateDownload`]
/// * [`UpdaterError::UnableToCreateTempDir`]
/// * [`UpdaterError::UnableToWriteToDownload`]
/// * [`UpdaterError::UnexpectedContentType`]
///
async fn download_update(&self, version: &Version) -> Result<(TempDir, PathBuf, Sha256Hash), UpdaterError> {
// Prepare file to download to
let download_dir = tempdir().map_err(|err| UpdaterError::UnableToCreateTempDir(err.to_string()))?;
let update_path = download_dir.path().join(format!("update-{version}"));
let mut file = AsyncFile::create(&update_path).await.map_err(|err|
UpdaterError::UnableToCreateDownload(update_path.clone(), err.to_string())
)?;
// Get headers
let (url, response) = self.request(&format!("releases/{version}")).await?;
let content_type: String = get_header(&response, CONTENT_TYPE);
let content_length: usize = get_header(&response, CONTENT_LENGTH);
// Check content type
if content_type != "application/octet-stream" {
return Err(UpdaterError::UnexpectedContentType(url, content_type, s!("application/octet-stream")));
}
// Download release to file
let mut response_stream = response.bytes_stream();
let mut hasher = Sha256::new();
let mut body_len = 0_usize;
// Download in chunks, and update the SHA256 hash along the way
while let Some(Ok(chunk)) = response_stream.next().await {
file.write_all(&chunk).await.map_err(|err|
UpdaterError::UnableToWriteToDownload(update_path.clone(), err.to_string())
)?;
hasher.update(&chunk);
body_len = body_len.saturating_add(chunk.len());
#[cfg_attr( feature = "reasons", allow(clippy::cast_possible_truncation, reason = "Loss of precision is not important here"))]
#[cfg_attr(not(feature = "reasons"), allow(clippy::cast_possible_truncation))]
#[cfg_attr( feature = "reasons", allow(clippy::cast_precision_loss, reason = "Loss of precision is not important here"))]
#[cfg_attr(not(feature = "reasons"), allow(clippy::cast_precision_loss))]
#[cfg_attr( feature = "reasons", allow(clippy::cast_sign_loss, reason = "Loss of sign is not important here"))]
#[cfg_attr(not(feature = "reasons"), allow(clippy::cast_sign_loss))]
self.set_status(Status::Downloading(version.clone(), (body_len as f64 / content_length as f64 * 100.0) as u8));
}
// Check content length
if body_len < content_length {
return Err(UpdaterError::MissingData(url, body_len, content_length));
}
if body_len > content_length {
return Err(UpdaterError::TooMuchData(url, body_len, content_length));
}
Ok((download_dir, update_path, hasher.finalize().into()))
}
// verify_update
/// Verifies an application update.
///
/// This function checks that the SHA256 hash of a downloaded file matches
/// the hash provided by the API server.
///
/// # Errors
///
/// * [`UpdaterError::InvalidPayload`]
/// * [`UpdaterError::FailedHashVerification`]
///
async fn verify_update(&self, version: &Version, hash: Sha256Hash) -> Result<(), UpdaterError> {
let (url, response) = self.request(&format!("hashes/{version}")).await?;
match self.decode_and_verify::<VersionHashResponse>(url.clone(), response).await {
Ok(json) => {
if json.version != *version {
return Err(UpdaterError::InvalidPayload(url));
}
if json.hash != hash {
return Err(UpdaterError::FailedHashVerification(version.clone()));
}
Ok(())
},
Err(err) => Err(err),
}
}
// request
/// Make HTTP request.
///
/// This function is responsible for handling communications with the API
/// server.
///
/// # Errors
///
/// * [`UpdaterError::HttpError`]
/// * [`UpdaterError::HttpRequestFailed`]
/// * [`UpdaterError::InvalidUrl`]
///
async fn request(&self, endpoint: &str) -> Result<(Url, Response), UpdaterError> {
// Perform request
let Ok(url) = self.config.api.join(endpoint) else {
return Err(UpdaterError::InvalidUrl(self.config.api.clone(), endpoint.to_owned()));
};
let response = self.http_client.get(url.clone()).send().await.map_err(|err|
UpdaterError::HttpRequestFailed(url.clone(), err.to_string())
)?;
// Check status
let status = response.status();
if !status.is_success() {
return Err(UpdaterError::HttpError(url, status));
}
Ok((url, response))
}
// decode_and_verify
/// Decodes a JSON HTTP response body and verifies signature.
///
/// This function accepts an HTTP response that contains a JSON payload,
/// decodes it, and verifies the signature against the public key.
///
/// # Errors
///
/// * [`UpdaterError::FailedSignatureVerification`]
/// * [`UpdaterError::InvalidBody`]
/// * [`UpdaterError::InvalidPayload`]
/// * [`UpdaterError::InvalidSignature`]
/// * [`UpdaterError::MissingData`]
/// * [`UpdaterError::MissingSignature`]
/// * [`UpdaterError::TooMuchData`]
/// * [`UpdaterError::UnexpectedContentType`]
///
async fn decode_and_verify<T: DeserializeOwned>(&self, url: Url, response: Response) -> Result<T, UpdaterError> {
// Get headers
let content_type: String = get_header(&response, CONTENT_TYPE);
let content_length: usize = get_header(&response, CONTENT_LENGTH);
let signature: String = get_header(&response, "x-signature");
// Get body
let Ok(body) = response.text().await else {
return Err(UpdaterError::InvalidBody(url))
};
// Check headers
if content_type != "application/json" {
return Err(UpdaterError::UnexpectedContentType(url, content_type, s!("application/json")));
}
if body.len() < content_length {
return Err(UpdaterError::MissingData(url, body.len(), content_length));
}
if body.len() > content_length {
return Err(UpdaterError::TooMuchData(url, body.len(), content_length));
}
if signature.is_empty() {
return Err(UpdaterError::MissingSignature(url));
}
// Verify payload against signature
let Ok(signature_bytes) = hex::decode(&signature) else {
return Err(UpdaterError::InvalidSignature(url, signature))
};
let signature_array: &[u8; 64] = signature_bytes.as_slice().try_into().map_err(|_err|
UpdaterError::InvalidSignature(url.clone(), signature)
)?;
if self.config.key.verify_strict(body.as_bytes(), &Signature::from_bytes(signature_array)).is_err() {
return Err(UpdaterError::FailedSignatureVerification(url));
}
// Decode payload
let Ok(parsed) = serde_json::from_str::<T>(&body) else {
return Err(UpdaterError::InvalidPayload(url));
};
Ok(parsed)
}
// replace_executable
/// Replaces the current executable with the updated one.
///
/// This function renames the currently-running executable with a `.old`
/// suffix, and moves the downloaded update into its place.
///
/// Note that at present it naively assumes that the backup filename doesn't
/// exist. It also does not attempt to rename the backup executable back to
/// the original name if moving the new executable fails. This behaviour
/// will be improved in future.
///
/// # Errors
///
/// * [`UpdaterError::UnableToGetFileMetadata`]
/// * [`UpdaterError::UnableToMoveNewExe`]
/// * [`UpdaterError::UnableToRenameCurrentExe`]
/// * [`UpdaterError::UnableToSetFilePermissions`]
///
async fn replace_executable(&self, update_path: &PathBuf) -> Result<(), UpdaterError> {
let current_path = self.exe_path.clone();
let backup_path = current_path.with_extension("old");
let move_error = |err: IoError| -> UpdaterError {
UpdaterError::UnableToMoveNewExe(update_path.clone(), err.to_string())
};
fs::rename(¤t_path, &backup_path).await.map_err(|err|
UpdaterError::UnableToRenameCurrentExe(current_path.clone(), err.to_string())
)?;
if let Err(err) = fs::rename(&update_path, ¤t_path).await {
// Check for cross-device move error and fall back to copy + delete. 18 is
// a magic number for the error code for `EXDEV` (cross-device link), which
// is not available in the standard library.
if err.raw_os_error() != Some(18_i32) {
return Err(move_error(err));
}
let _size = fs::copy(&update_path, ¤t_path).await.map_err(move_error)?;
if let Err(err2) = fs::remove_file(&update_path).await {
warn!("Failed to delete temporary update file {update_path:?}: {err2}");
}
}
let mut permissions = fs::metadata(¤t_path).await.map_err(|err|
UpdaterError::UnableToGetFileMetadata(current_path.clone(), err.to_string())
)?.permissions();
// Add executable bits for all (owner, group, others)
permissions.set_mode(permissions.mode() | 0o111);
fs::set_permissions(¤t_path, permissions).await.map_err(|err|
UpdaterError::UnableToSetFilePermissions(current_path.clone(), err.to_string())
)?;
Ok(())
}
// restart
/// Restarts the application.
///
/// This function restarts the currently-running application, for the
/// primary purpose of replacing it with the newer version.
///
/// It does so while preserving all arguments originally specified. It will
/// inherit the standard I/O streams from the current process, ensuring
/// seamless input and output behaviour, and will replace the currently
/// running process with the new one.
///
/// If the application fails to restart, this function will log an error,
/// and then exit. In this situation there's not a lot else to do at
/// present, as behaviour in such a scenario is undefined, and given that
/// all critical actions have been paused, exiting seems the most sensible
/// option. This behaviour will be considered carefully and improved in
/// future when it becomes clearer how to handle it.
///
fn restart(&self) {
// Skip the first argument (current executable name)
let args = args().skip(1).collect::<Vec<_>>();
let err = Command::new(self.exe_path.clone())
.args(args)
.stdin(Stdio::inherit())
.stdout(Stdio::inherit())
.stderr(Stdio::inherit())
.exec()
;
// A failure to restart the application is fatal to the installer
// process, so although we won't panic, we also won't continue. We'll
// just exit the application. This is a candidate for potential
// improvement in future, to allow for more graceful handling of this
// situation.
error!("Failed to restart application: {err}");
exit(1);
}
//
}
// Drop
impl Drop for Updater {
// drop
fn drop(&mut self) {
// Send a message to the queue to stop the timer, ignoring any errors
let _ignored = self.queue.send(());
}
}
// Functions
// get_header
/// Gets a header from an HTTP response.
///
/// This function gets a header from an HTTP response, and converts it to the
/// specified type.
///
/// # Parameters
///
/// * `response` - The HTTP response to get the header from.
/// * `header` - The header to get from the response.
///
fn get_header<K, T>(response: &Response, header: K) -> T
where
K: AsHeaderName,
T: Default + FromStr
{
response.headers()
.get(header)
.and_then(|h| h.to_str().ok())
.and_then(|s| T::from_str(s).ok())
.unwrap_or_default()
}