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//! Code to collect and publish information about a client's bootstrapping
//! status.
use std::{borrow::Cow, fmt, fmt::Display, time::SystemTime};
use educe::Educe;
use futures::{Stream, StreamExt};
use tor_basic_utils::skip_fmt;
use tor_chanmgr::{ConnBlockage, ConnStatus, ConnStatusEvents};
use tor_circmgr::{ClockSkewEvents, SkewEstimate};
use tor_dirmgr::{DirBlockage, DirBootstrapStatus};
use tracing::debug;
/// Information about how ready a [`crate::TorClient`] is to handle requests.
///
/// Note that this status does not change monotonically: a `TorClient` can
/// become more _or less_ bootstrapped over time. (For example, a client can
/// become less bootstrapped if it loses its internet connectivity, or if its
/// directory information expires before it's able to replace it.)
//
// # Note
// We need to keep this type fairly small, since it will get cloned whenever
// it's observed on a stream. If it grows large, we can add an Arc<> around
// its data.
#[derive(Debug, Clone, Default)]
pub struct BootstrapStatus {
/// Status for our connection to the tor network
conn_status: ConnStatus,
/// Status for our directory information.
dir_status: DirBootstrapStatus,
/// Current estimate of our clock skew.
skew: Option<SkewEstimate>,
}
impl BootstrapStatus {
/// Return a rough fraction (from 0.0 to 1.0) representing how far along
/// the client's bootstrapping efforts are.
/// 0 is defined as "just started"; 1 is defined as "ready to use."
pub fn as_frac(&self) -> f32 {
// Coefficients chosen arbitrarily.
self.conn_status.frac() * 0.15 + self.dir_status.frac_at(SystemTime::now()) * 0.85
/// Return true if the status indicates that the client is ready for
/// traffic.
/// For the purposes of this function, the client is "ready for traffic" if,
/// as far as we know, we can start acting on a new client request immediately.
pub fn ready_for_traffic(&self) -> bool {
let now = SystemTime::now();
self.conn_status.usable() && self.dir_status.usable_at(now)
/// If the client is unable to make forward progress for some reason, return
/// that reason.
/// (Returns None if the client doesn't seem to be stuck.)
/// # Caveats
/// This function provides a "best effort" diagnostic: there
/// will always be some blockage types that it can't diagnose
/// correctly. It may declare that Arti is stuck for reasons that
/// are incorrect; or it may declare that the client is not stuck
/// when in fact no progress is being made.
/// Therefore, the caller should always use a certain amount of
/// modesty when reporting these values to the user. For example,
/// it's probably better to say "Arti says it's stuck because it
/// can't make connections to the internet" rather than "You are
/// not on the internet."
pub fn blocked(&self) -> Option<Blockage> {
if let Some(b) = self.conn_status.blockage() {
let message = b.to_string().into();
let kind = b.into();
if matches!(kind, BlockageKind::ClockSkewed) && self.skew_is_noteworthy() {
Some(Blockage {
kind,
message: format!("Clock is {}", self.skew.as_ref().expect("logic error"))
.into(),
})
} else {
Some(Blockage { kind, message })
} else if let Some(b) = self.dir_status.blockage(SystemTime::now()) {
None
/// Adjust this status based on new connection-status information.
fn apply_conn_status(&mut self, status: ConnStatus) {
self.conn_status = status;
/// Adjust this status based on new directory-status information.
fn apply_dir_status(&mut self, status: DirBootstrapStatus) {
self.dir_status = status;
/// Adjust this status based on new estimated clock skew information.
fn apply_skew_estimate(&mut self, status: Option<SkewEstimate>) {
self.skew = status;
/// Return true if our current clock skew estimate is considered noteworthy.
fn skew_is_noteworthy(&self) -> bool {
matches!(&self.skew, Some(s) if s.noteworthy())
/// A reason why a client believes it is stuck.
#[derive(Clone, Debug, derive_more::Display)]
#[display("{} ({})", kind, message)]
pub struct Blockage {
/// Why do we think we're blocked?
kind: BlockageKind,
/// A human-readable message about the blockage.
message: Cow<'static, str>,
impl Blockage {
/// Get a programmatic indication of the kind of blockage this is.
pub fn kind(&self) -> BlockageKind {
self.kind.clone()
/// Get a human-readable message about the blockage.
pub fn message(&self) -> impl Display + '_ {
&self.message
/// A specific type of blockage that a client believes it is experiencing.
/// Used to distinguish among instances of [`Blockage`].
#[non_exhaustive]
pub enum BlockageKind {
/// There is some kind of problem with connecting to the network.
#[display("We seem to be offline")]
Offline,
/// We can connect, but our connections seem to be filtered.
#[display("Our internet connection seems filtered")]
Filtering,
/// We have some other kind of problem connecting to Tor
#[display("Can't reach the Tor network")]
CantReachTor,
/// We believe our clock is set incorrectly, and that's preventing us from
/// successfully with relays and/or from finding a directory that we trust.
#[display("Clock is skewed.")]
ClockSkewed,
/// We've encountered some kind of problem downloading directory
/// information, and it doesn't seem to be caused by any particular
/// connection problem.
#[display("Can't bootstrap a Tor directory.")]
CantBootstrap,
impl From<ConnBlockage> for BlockageKind {
fn from(b: ConnBlockage) -> BlockageKind {
match b {
ConnBlockage::NoTcp => BlockageKind::Offline,
ConnBlockage::NoHandshake => BlockageKind::Filtering,
ConnBlockage::CertsExpired => BlockageKind::ClockSkewed,
_ => BlockageKind::CantReachTor,
impl From<DirBlockage> for BlockageKind {
fn from(_: DirBlockage) -> Self {
BlockageKind::CantBootstrap
impl fmt::Display for BootstrapStatus {
/// Format this [`BootstrapStatus`].
/// Note that the string returned by this function is designed for human
/// readability, not for machine parsing. Other code *should not* depend
/// on particular elements of this string.
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let percent = (self.as_frac() * 100.0).round() as u32;
if let Some(problem) = self.blocked() {
write!(f, "Stuck at {}%: {}", percent, problem)?;
write!(
f,
"{}%: {}; {}",
percent, &self.conn_status, &self.dir_status
)?;
if let Some(skew) = &self.skew {
if skew.noteworthy() {
write!(f, ". Clock is {}", skew)?;
Ok(())
/// Task that runs forever, updating a client's status via the provided
/// `sender`.
/// TODO(nickm): Eventually this will use real stream of events to see when we
/// are bootstrapped or not. For now, it just says that we're not-ready until
/// the given Receiver fires.
/// TODO(nickm): This should eventually close the stream when the client is
/// dropped.
pub(crate) async fn report_status(
mut sender: postage::watch::Sender<BootstrapStatus>,
conn_status: ConnStatusEvents,
dir_status: impl Stream<Item = DirBootstrapStatus> + Send + Unpin,
skew_status: ClockSkewEvents,
) {
/// Internal enumeration to combine incoming status changes.
#[allow(clippy::large_enum_variant)]
enum Event {
/// A connection status change
Conn(ConnStatus),
/// A directory status change
Dir(DirBootstrapStatus),
/// A clock skew change
Skew(Option<SkewEstimate>),
let mut stream = futures::stream::select_all(vec![
conn_status.map(Event::Conn).boxed(),
dir_status.map(Event::Dir).boxed(),
skew_status.map(Event::Skew).boxed(),
]);
while let Some(event) = stream.next().await {
let mut b = sender.borrow_mut();
match event {
Event::Conn(e) => b.apply_conn_status(e),
Event::Dir(e) => b.apply_dir_status(e),
Event::Skew(e) => b.apply_skew_estimate(e),
debug!("{}", *b);
/// A [`Stream`] of [`BootstrapStatus`] events.
/// This stream isn't guaranteed to receive every change in bootstrap status; if
/// changes happen more frequently than the receiver can observe, some of them
/// will be dropped.
// Note: We use a wrapper type around watch::Receiver here, in order to hide its
// implementation type. We do that because we might want to change the type in
// the future, and because some of the functionality exposed by Receiver (like
// `borrow()` and the postage::Stream trait) are extraneous to the API we want.
#[derive(Clone, Educe)]
#[educe(Debug)]
pub struct BootstrapEvents {
/// The receiver that implements this stream.
#[educe(Debug(method = "skip_fmt"))]
pub(crate) inner: postage::watch::Receiver<BootstrapStatus>,
impl Stream for BootstrapEvents {
type Item = BootstrapStatus;
fn poll_next(
mut self: std::pin::Pin<&mut Self>,
cx: &mut std::task::Context<'_>,
) -> std::task::Poll<Option<Self::Item>> {
self.inner.poll_next_unpin(cx)