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#![cfg_attr(docsrs, feature(doc_auto_cfg, doc_cfg))]
#![doc = include_str!("../README.md")]
// @@ begin lint list maintained by maint/add_warning @@
#![allow(renamed_and_removed_lints)] // @@REMOVE_WHEN(ci_arti_stable)
#![allow(unknown_lints)] // @@REMOVE_WHEN(ci_arti_nightly)
#![warn(missing_docs)]
#![warn(noop_method_call)]
#![warn(unreachable_pub)]
#![warn(clippy::all)]
#![deny(clippy::await_holding_lock)]
#![deny(clippy::cargo_common_metadata)]
#![deny(clippy::cast_lossless)]
#![deny(clippy::checked_conversions)]
#![warn(clippy::cognitive_complexity)]
#![deny(clippy::debug_assert_with_mut_call)]
#![deny(clippy::exhaustive_enums)]
#![deny(clippy::exhaustive_structs)]
#![deny(clippy::expl_impl_clone_on_copy)]
#![deny(clippy::fallible_impl_from)]
#![deny(clippy::implicit_clone)]
#![deny(clippy::large_stack_arrays)]
#![warn(clippy::manual_ok_or)]
#![deny(clippy::missing_docs_in_private_items)]
#![warn(clippy::needless_borrow)]
#![warn(clippy::needless_pass_by_value)]
#![warn(clippy::option_option)]
#![deny(clippy::print_stderr)]
#![deny(clippy::print_stdout)]
#![warn(clippy::rc_buffer)]
#![deny(clippy::ref_option_ref)]
#![warn(clippy::semicolon_if_nothing_returned)]
#![warn(clippy::trait_duplication_in_bounds)]
#![deny(clippy::unchecked_duration_subtraction)]
#![deny(clippy::unnecessary_wraps)]
#![warn(clippy::unseparated_literal_suffix)]
#![deny(clippy::unwrap_used)]
#![allow(clippy::let_unit_value)] // This can reasonably be done for explicitness
#![allow(clippy::uninlined_format_args)]
#![allow(clippy::significant_drop_in_scrutinee)] // arti/-/merge_requests/588/#note_2812945
#![allow(clippy::result_large_err)] // temporary workaround for arti#587
#![allow(clippy::needless_raw_string_hashes)] // complained-about code is fine, often best
//! <!-- @@ end lint list maintained by maint/add_warning @@ -->
pub mod config;
pub mod err;
pub mod ipc;
use crate::config::TransportConfig;
use crate::err::PtError;
use crate::ipc::{
sealed::PluggableTransportPrivate, PluggableClientTransport, PluggableTransport,
PtClientMethod, PtClientParameters, PtCommonParameters,
};
use futures::channel::mpsc::{self, UnboundedReceiver, UnboundedSender};
use futures::stream::FuturesUnordered;
use futures::task::SpawnExt;
use futures::{select, FutureExt, StreamExt};
use std::collections::{HashMap, HashSet};
use std::future::Future;
use std::path::{Path, PathBuf};
use std::pin::Pin;
use std::sync::{Arc, RwLock};
use tor_async_utils::oneshot;
use tor_error::{error_report, internal};
use tor_linkspec::PtTransportName;
use tor_rtcompat::Runtime;
use tracing::{debug, info, trace, warn};
#[cfg(feature = "tor-channel-factory")]
use {
async_trait::async_trait,
tor_chanmgr::{
builder::ChanBuilder,
factory::{AbstractPtError, ChannelFactory},
transport::ExternalProxyPlugin,
},
};
/// Shared mutable state between the `PtReactor` and `PtMgr`.
#[derive(Default, Debug)]
struct PtSharedState {
/// Connection information for pluggable transports from currently running binaries.
///
/// Unmanaged pluggable transports are not included in this map.
managed_cmethods: HashMap<PtTransportName, PtClientMethod>,
/// Current configured set of pluggable transports.
configured: HashMap<PtTransportName, TransportConfig>,
}
/// A message to the `PtReactor`.
enum PtReactorMessage {
/// Notify the reactor that the currently configured set of PTs has changed.
Reconfigured,
/// Ask the reactor to spawn a pluggable transport binary.
Spawn {
/// Spawn a binary to provide this PT.
pt: PtTransportName,
/// Notify the result via this channel.
result: oneshot::Sender<err::Result<PtClientMethod>>,
},
}
/// The result of a spawn attempt: the list of transports the spawned binary covers, and the result.
type SpawnResult = (Vec<PtTransportName>, err::Result<PluggableClientTransport>);
/// Background reactor to handle managing pluggable transport binaries.
struct PtReactor<R> {
/// Runtime.
rt: R,
/// Currently running pluggable transport binaries.
running: Vec<PluggableClientTransport>,
/// A map of asked-for transports.
///
/// If a transport name has an entry, we will append any additional requests for that entry.
/// If no entry is present, we will start a request.
requests: HashMap<PtTransportName, Vec<oneshot::Sender<err::Result<PtClientMethod>>>>,
/// FuturesUnordered that spawned tasks get pushed on to.
///
/// WARNING: This MUST always contain one "will never resolve" future!
spawning: FuturesUnordered<Pin<Box<dyn Future<Output = SpawnResult> + Send>>>,
/// State for the corresponding PtMgr.
state: Arc<RwLock<PtSharedState>>,
/// PtMgr channel.
/// (Unbounded so that we can reconfigure without blocking: we're unlikely to have the reactor
/// get behind.)
rx: UnboundedReceiver<PtReactorMessage>,
/// State directory.
state_dir: PathBuf,
}
impl<R: Runtime> PtReactor<R> {
/// Make a new reactor.
fn new(
rt: R,
state: Arc<RwLock<PtSharedState>>,
rx: UnboundedReceiver<PtReactorMessage>,
state_dir: PathBuf,
) -> Self {
let spawning = FuturesUnordered::new();
spawning.push(Box::pin(futures::future::pending::<SpawnResult>())
as Pin<Box<dyn Future<Output = _> + Send>>);
Self {
rt,
running: vec![],
requests: Default::default(),
spawning,
state,
rx,
state_dir,
}
}
/// Called when a spawn request completes.
#[allow(clippy::needless_pass_by_value)]
fn handle_spawned(
&mut self,
covers: Vec<PtTransportName>,
result: err::Result<PluggableClientTransport>,
) {
match result {
Err(e) => {
warn!("Spawning PT for {:?} failed: {}", covers, e);
// Go and tell all the transports about the bad news.
let senders = covers
.iter()
.flat_map(|x| self.requests.remove(x))
.flatten();
for sender in senders {
// We don't really care if the sender went away.
let _ = sender.send(Err(e.clone()));
}
}
Ok(pt) => {
let mut state = self.state.write().expect("ptmgr state poisoned");
for (transport, method) in pt.transport_methods() {
state
.managed_cmethods
.insert(transport.clone(), method.clone());
for sender in self.requests.remove(transport).into_iter().flatten() {
let _ = sender.send(Ok(method.clone()));
}
}
let requested: HashSet<_> = covers.iter().collect();
let found: HashSet<_> = pt.transport_methods().iter().map(|(t, _)| t).collect();
if requested != found {
warn!("Bug: PT {} succeeded, but did not give the same transports we asked for. ({:?} vs {:?})",
pt.identifier(), found, requested);
}
self.running.push(pt);
}
}
}
/// Called to remove a pluggable transport from the shared state.
fn remove_pt(&self, pt: PluggableClientTransport) {
let mut state = self.state.write().expect("ptmgr state poisoned");
for transport in pt.transport_methods().keys() {
state.managed_cmethods.remove(transport);
}
// to satisfy clippy, and make it clear that this is a desired side-effect: doing this
// shuts down the PT (asynchronously).
drop(pt);
}
/// Run one step of the reactor. Returns true if the reactor should terminate.
async fn run_one_step(&mut self) -> err::Result<bool> {
use futures::future::Either;
// FIXME(eta): This allocates a lot, which is technically unnecessary but requires careful
// engineering to get right. It's not really in the hot path, at least.
let mut all_next_messages = self
.running
.iter_mut()
// We could avoid the Box, but that'd require using unsafe to replicate what tokio::pin!
// does under the hood.
.map(|pt| Box::pin(pt.next_message()))
.collect::<Vec<_>>();
// We can't construct a select_all if all_next_messages is empty.
let mut next_message = if all_next_messages.is_empty() {
Either::Left(futures::future::pending())
} else {
Either::Right(futures::future::select_all(all_next_messages.iter_mut()).fuse())
};
select! {
(result, idx, _) = next_message => {
drop(all_next_messages); // no idea why NLL doesn't just infer this but sure
match result {
Ok(m) => {
// FIXME(eta): We should forward the Status messages onto API consumers.
debug!("PT {} message: {:?}", self.running[idx].identifier(), m);
},
Err(e) => {
warn!("PT {} quit: {:?}", self.running[idx].identifier(), e);
let pt = self.running.remove(idx);
self.remove_pt(pt);
}
}
},
spawn_result = self.spawning.next() => {
drop(all_next_messages);
// See the Warning in this field's documentation.
let (covers, result) = spawn_result.expect("self.spawning should never dry up");
self.handle_spawned(covers, result);
}
internal = self.rx.next() => {
drop(all_next_messages);
match internal {
Some(PtReactorMessage::Reconfigured) => {},
Some(PtReactorMessage::Spawn { pt, result }) => {
// Make sure we don't already have a running request.
if let Some(requests) = self.requests.get_mut(&pt) {
requests.push(result);
return Ok(false);
}
// Make sure we don't already have a binary for this PT.
for rpt in self.running.iter() {
if let Some(cmethod) = rpt.transport_methods().get(&pt) {
let _ = result.send(Ok(cmethod.clone()));
return Ok(false);
}
}
// We don't, so time to spawn one.
let config = {
let state = self.state.read().expect("ptmgr state poisoned");
state.configured.get(&pt).cloned()
};
let config = match config {
Some(v) if v.is_managed() => v,
Some(_) => {
let _ = result.send(Err(internal!("Tried to spawn an unmanaged transport").into()));
return Ok(false);
}
None => {
let _ = result.send(Err(PtError::UnconfiguredTransportDueToConcurrentReconfiguration));
return Ok(false);
}
};
// Keep track of the request, and also fill holes in other protocols so
// we don't try and run another spawn request for those.
self.requests.entry(pt).or_default().push(result);
for proto in config.protocols.iter() {
self.requests.entry(proto.clone()).or_default();
}
// Add the spawn future to our pile of them.
let spawn_fut = Box::pin(
spawn_from_config(self.rt.clone(), self.state_dir.clone(), config.clone())
.map(|result| (config.protocols, result))
);
self.spawning.push(spawn_fut);
},
None => return Ok(true)
}
}
}
Ok(false)
}
}
/// A pluggable transport manager knows how to make different
/// kinds of connections to the Tor network, for censorship avoidance.
pub struct PtMgr<R> {
/// An underlying `Runtime`, used to spawn background tasks.
#[allow(dead_code)]
runtime: R,
/// State for this PtMgr.
state: Arc<RwLock<PtSharedState>>,
/// PtReactor channel.
tx: UnboundedSender<PtReactorMessage>,
}
impl<R: Runtime> PtMgr<R> {
/// Transform the config into a more useful representation indexed by transport name.
fn transform_config(
binaries: Vec<TransportConfig>,
) -> HashMap<PtTransportName, TransportConfig> {
let mut ret = HashMap::new();
// FIXME(eta): You can currently specify overlapping protocols, and it'll
// just use the last transport specified.
// I attempted to fix this, but decided I didn't want to stare into the list
// builder macro void after trying it for 15 minutes.
for thing in binaries {
for tn in thing.protocols.iter() {
ret.insert(tn.clone(), thing.clone());
}
}
ret
}
/// Create a new PtMgr.
// TODO: maybe don't have the Vec directly exposed?
pub fn new(
transports: Vec<TransportConfig>,
state_dir: PathBuf,
rt: R,
) -> Result<Self, PtError> {
let state = PtSharedState {
managed_cmethods: Default::default(),
configured: Self::transform_config(transports),
};
let state = Arc::new(RwLock::new(state));
let (tx, rx) = mpsc::unbounded();
let mut reactor = PtReactor::new(rt.clone(), state.clone(), rx, state_dir);
rt.spawn(async move {
loop {
match reactor.run_one_step().await {
Ok(true) => return,
Ok(false) => {}
Err(e) => {
error_report!(e, "PtReactor failed");
return;
}
}
}
})
.map_err(|e| PtError::Spawn { cause: Arc::new(e) })?;
Ok(Self {
runtime: rt,
state,
tx,
})
}
/// Reload the configuration
pub fn reconfigure(
&self,
how: tor_config::Reconfigure,
transports: Vec<TransportConfig>,
) -> Result<(), tor_config::ReconfigureError> {
let configured = Self::transform_config(transports);
if how == tor_config::Reconfigure::CheckAllOrNothing {
return Ok(());
}
{
let mut inner = self.state.write().expect("ptmgr poisoned");
inner.configured = configured;
}
// We don't have any way of propagating this sanely; the caller will find out the reactor
// has died later on anyway.
let _ = self.tx.unbounded_send(PtReactorMessage::Reconfigured);
Ok(())
}
/// Given a transport name, return a method that we can use to contact that transport.
///
/// May have to launch a managed transport as needed.
///
/// Returns Ok(None) if no such transport exists.
async fn get_cmethod_for_transport(
&self,
transport: &PtTransportName,
) -> Result<Option<PtClientMethod>, PtError> {
// NOTE(eta): This is using a RwLock inside async code (but not across an await point).
// Arguably this is fine since it's just a small read, and nothing should ever
// hold this lock for very long.
let (cmethod, configured) = {
let inner = self.state.read().expect("ptmgr poisoned");
let cfg = inner.configured.get(transport);
if let Some(cmethod) = cfg.and_then(TransportConfig::cmethod_for_unmanaged_pt) {
// We have a unmanaged transport; that was easy.
(Some(cmethod), true)
} else {
let cmethod = inner.managed_cmethods.get(transport).cloned();
let configured = cmethod.is_some() || cfg.is_some();
(cmethod, configured)
}
};
match (cmethod, configured) {
// There is going to be a lot happening "under the hood" here.
//
// When we are asked to get a ChannelFactory for a given
// connection, we will need to:
// - launch the binary for that transport if it is not already running*.
// - If we launched the binary, talk to it and see which ports it
// is listening on.
// - Return a ChannelFactory that connects via one of those ports,
// using the appropriate version of SOCKS, passing K=V parameters
// encoded properly.
//
// * As in other managers, we'll need to avoid trying to launch the same
// transport twice if we get two concurrent requests.
//
// Later if the binary crashes, we should detect that. We should relaunch
// it on demand.
//
// On reconfigure, we should shut down any no-longer-used transports.
//
// Maybe, we should shut down transports that haven't been used
// for a long time.
(None, true) => {
// A configured-but-not-running cmethod.
//
// Tell the reactor to spawn the PT, and wait for it.
// (The reactor will handle coalescing multiple requests.)
info!(
"Got a request for transport {}, which is not currently running. Launching it.",
transport
);
let (tx, rx) = oneshot::channel();
self.tx
.unbounded_send(PtReactorMessage::Spawn {
pt: transport.clone(),
result: tx,
})
.map_err(|_| {
PtError::Internal(tor_error::internal!("PT reactor closed unexpectedly"))
})?;
let method =
// NOTE(eta): Could be improved with result flattening.
rx.await
.map_err(|_| {
PtError::Internal(tor_error::internal!(
"PT reactor closed unexpectedly"
))
})?
.map_err(|x| {
warn!("PT for {} failed to launch: {}", transport, x);
x
})?;
info!(
"Successfully launched PT for {} at {:?}.",
transport, &method
);
Ok(Some(method))
}
(None, false) => {
trace!(
"Got a request for transport {}, which is not configured.",
transport
);
Ok(None)
}
(Some(cmethod), _) => {
trace!(
"Found configured transport {} accessible via {:?}",
transport,
cmethod
);
Ok(Some(cmethod))
}
}
}
}
/// Spawn a managed `PluggableTransport` using a `TransportConfig`.
///
/// Requires that the transport is a managed transport.
async fn spawn_from_config<R: Runtime>(
rt: R,
state_dir: PathBuf,
cfg: TransportConfig,
) -> Result<PluggableClientTransport, PtError> {
// FIXME(eta): I really think this expansion should happen at builder validation time...
let cfg_path = cfg
.path
.as_ref()
.ok_or_else(|| internal!("spawn_from_config on an unmanaged transport."))?;
let binary_path = cfg_path.path().map_err(|e| PtError::PathExpansionFailed {
path: cfg_path.clone(),
error: e,
})?;
let filename = pt_identifier_as_path(&binary_path)?;
// HACK(eta): Currently the state directory is named after the PT binary name. Maybe we should
// invent a better way of doing this?
let new_state_dir = state_dir.join(filename);
std::fs::create_dir_all(&new_state_dir).map_err(|e| PtError::StatedirCreateFailed {
path: new_state_dir.clone(),
error: Arc::new(e),
})?;
// FIXME(eta): make the rest of these parameters configurable
let pt_common_params = PtCommonParameters::builder()
.state_location(new_state_dir)
.build()
.expect("PtCommonParameters constructed incorrectly");
let pt_client_params = PtClientParameters::builder()
.transports(cfg.protocols)
.build()
.expect("PtClientParameters constructed incorrectly");
let mut pt = PluggableClientTransport::new(
binary_path,
cfg.arguments,
pt_common_params,
pt_client_params,
);
pt.launch(rt).await?;
Ok(pt)
}
#[cfg(feature = "tor-channel-factory")]
#[async_trait]
impl<R: Runtime> tor_chanmgr::factory::AbstractPtMgr for PtMgr<R> {
async fn factory_for_transport(
&self,
transport: &PtTransportName,
) -> Result<Option<Arc<dyn ChannelFactory + Send + Sync>>, Arc<dyn AbstractPtError>> {
let cmethod = match self.get_cmethod_for_transport(transport).await {
Err(e) => return Err(Arc::new(e)),
Ok(None) => return Ok(None),
Ok(Some(m)) => m,
};
let proxy = ExternalProxyPlugin::new(self.runtime.clone(), cmethod.endpoint, cmethod.kind);
let factory = ChanBuilder::new(self.runtime.clone(), proxy);
// FIXME(eta): Should we cache constructed factories? If no: should this still be an Arc?
// FIXME(eta): Should we track what transports are live somehow, so we can shut them down?
Ok(Some(Arc::new(factory)))
}
}
/// Given a path to a binary for a pluggable transport, return an identifier for
/// that binary in a format that can be used as a path component.
fn pt_identifier_as_path(binary_path: impl AsRef<Path>) -> Result<PathBuf, PtError> {
// Extract the final component.
let mut filename =
PathBuf::from(
binary_path
.as_ref()
.file_name()
.ok_or_else(|| PtError::NotAFile {
path: binary_path.as_ref().to_path_buf(),
})?,
);
// Strip an "exe" off the end, if appropriate.
if let Some(ext) = filename.extension() {
if ext.eq_ignore_ascii_case(std::env::consts::EXE_EXTENSION) {
filename.set_extension("");
}
}
Ok(filename)
}
/// Given a path to a binary for a pluggable transport, return an identifier for
/// that binary in human-readable form.
fn pt_identifier(binary_path: impl AsRef<Path>) -> Result<String, PtError> {
Ok(pt_identifier_as_path(binary_path)?
.to_string_lossy()
.to_string())
}