#![cfg_attr(docsrs, feature(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_time_subtraction)]

#![deny(clippy::unnecessary_wraps)]

#![warn(clippy::unseparated_literal_suffix)]

#![deny(clippy::unwrap_used)]

#![deny(clippy::mod_module_files)]

#![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

#![allow(clippy::needless_lifetimes)] // See arti#1765

#![allow(mismatched_lifetime_syntaxes)] // temporary workaround for arti#2060

#![allow(clippy::collapsible_if)] // See arti#2342

#![deny(clippy::unused_async)]

//! <!-- @@ end lint list maintained by maint/add_warning @@ -->

pub mod builder;

mod config;

mod err;

mod event;

pub mod factory;

mod mgr;

#[cfg(test)]

mod testing;

pub mod transport;

pub(crate) mod util;

use futures::StreamExt;

use futures::select_biased;

use std::result::Result as StdResult;

use std::sync::{Arc, Weak};

use std::time::Duration;

use tor_config::ReconfigureError;

use tor_error::error_report;

use tor_linkspec::{ChanTarget, OwnedChanTarget};

use tor_netdir::{NetDirProvider, params::NetParameters};

use tor_proto::channel::Channel;

#[cfg(feature = "experimental-api")]

use tor_proto::memquota::ChannelAccount;

use tor_proto::memquota::ToplevelAccount;

use tor_rtcompat::SpawnExt;

use tracing::debug;

use tracing::instrument;

use void::{ResultVoidErrExt, Void};

#[cfg(feature = "relay")]

use {

    async_trait::async_trait, safelog::Sensitive,

    tor_proto::relay::channel_provider::ChannelProvider,

};

pub use err::Error;

pub use config::{ChannelConfig, ChannelConfigBuilder};

pub use mgr::ChanMgrConfig;

use tor_rtcompat::Runtime;

/// A Result as returned by this crate.

pub type Result<T> = std::result::Result<T, Error>;

use crate::factory::BootstrapReporter;

pub use event::{ConnBlockage, ConnStatus, ConnStatusEvents};

use tor_rtcompat::scheduler::{TaskHandle, TaskSchedule};

/// An object that remembers a set of live channels, and launches new ones on

/// request.

///

/// Use the [`ChanMgr::get_or_launch`] function to create a new [`Channel`], or

/// get one if it exists.  (For a slightly lower-level API that does no caching,

/// see [`ChannelFactory`](factory::ChannelFactory) and its implementors.

///

/// Each channel is kept open as long as there is a reference to it, or

/// something else (such as the relay or a network error) kills the channel.

///

/// After a `ChanMgr` launches a channel, it keeps a reference to it until that

/// channel has been unused (that is, had no circuits attached to it) for a

/// certain amount of time. (Currently this interval is chosen randomly from

/// between 180-270 seconds, but this is an implementation detail that may change

/// in the future.)

pub struct ChanMgr<R: Runtime> {

    /// Internal channel manager object that does the actual work.

    ///

    /// ## How this is built

    ///

    /// This internal manager is parameterized over an

    /// [`mgr::AbstractChannelFactory`], which here is instantiated with a [`factory::CompoundFactory`].

    /// The `CompoundFactory` itself holds:

    ///   * A `dyn` [`factory::AbstractPtMgr`] that can provide a `dyn`

    ///     [`factory::ChannelFactory`] for each supported pluggable transport.

    ///     This starts out as `None`, but can be replaced with [`ChanMgr::set_pt_mgr`].

    ///     The `TorClient` code currently sets this using `tor_ptmgr::PtMgr`.

    ///     `PtMgr` currently returns `ChannelFactory` implementations that are

    ///     built using [`transport::proxied::ExternalProxyPlugin`], which implements

    ///     [`transport::TransportImplHelper`], which in turn is wrapped into a

    ///     `ChanBuilder` to implement `ChannelFactory`.

    ///   * A generic [`factory::ChannelFactory`] that it uses for everything else

    ///     We instantiate this with a

    ///     [`builder::ChanBuilder`] using a [`transport::default::DefaultTransport`].

    // This type is a bit long, but I think it's better to just state it here explicitly rather than

    // hiding parts of it behind a type alias to make it look nicer.

    mgr: mgr::AbstractChanMgr<

        factory::CompoundFactory<builder::ChanBuilder<R, transport::DefaultTransport<R>>>,

    >,

    /// Stream of [`ConnStatus`] events.

    bootstrap_status: event::ConnStatusEvents,

    /// The runtime. Needed to possibly spawn tasks.

    #[allow(unused)] // Relay use this, not client yet. Keep it here instead of gating.

    runtime: R,

}

/// Description of how we got a channel.

#[non_exhaustive]

#[derive(Debug, Copy, Clone, Eq, PartialEq)]

pub enum ChanProvenance {

    /// This channel was newly launched, or was in progress and finished while

    /// we were waiting.

    NewlyCreated,

    /// This channel already existed when we asked for it.

    Preexisting,

}

/// Dormancy state, as far as the channel manager is concerned

///

/// This is usually derived in higher layers from `arti_client::DormantMode`.

#[non_exhaustive]

#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]

pub enum Dormancy {

    /// Not dormant

    ///

    /// Channels will operate normally.

    #[default]

    Active,

    /// Totally dormant

    ///

    /// Channels will not perform any spontaneous activity (eg, netflow padding)

    Dormant,

}

/// The usage that we have in mind when requesting a channel.

///

/// A channel may be used in multiple ways.  Each time a channel is requested

/// from `ChanMgr` a separate `ChannelUsage` is passed in to tell the `ChanMgr`

/// how the channel will be used this time.

///

/// To be clear, the `ChannelUsage` is aspect of a _request_ for a channel, and

/// is not an immutable property of the channel itself.

///

/// This type is obtained from a `tor_circmgr::usage::SupportedCircUsage` in

/// `tor_circmgr::usage`, and it has roughly the same set of variants.

#[derive(Clone, Debug, Copy, Eq, PartialEq)]

#[non_exhaustive]

pub enum ChannelUsage {

    /// Requesting a channel to use for BEGINDIR-based non-anonymous directory

    /// connections.

    Dir,

    /// Requesting a channel to transmit user traffic (including exit traffic)

    /// over the network.

    ///

    /// This includes the case where we are constructing a circuit preemptively,

    /// and _planning_ to use it for user traffic later on.

    UserTraffic,

    /// Requesting a channel that the caller does not plan to used at all, or

    /// which it plans to use only for testing circuits.

    UselessCircuit,

}

impl<R: Runtime> ChanMgr<R> {

    /// Construct a new channel manager.

    ///

    /// A new `ChannelAccount` will be made from `memquota`, for each Channel.

    ///

    /// The `ChannelAccount` is used for data associated with this channel.

    ///

    /// This does *not* (currently) include downstream outbound data

    /// (ie, data processed by the channel implementation here,

    /// awaiting TLS processing and actual transmission).

    /// In any case we try to keep those buffers small.

    ///

    /// The ChannelAccount *does* track upstream outbound data

    /// (ie, data processed by a circuit, but not yet by the channel),

    /// even though that data relates to a specific circuit.

    /// TODO #1652 use `CircuitAccount` for circuit->channel queue.

    ///

    /// # Usage note

    ///

    /// For the manager to work properly, you will need to call `ChanMgr::launch_background_tasks`.

    ///

    /// The `keymgr` is only needed for a relay which is used for authenticating its channel to

    /// other relays. Pass `None` for a client.

    {

        cfg_if::cfg_if! {

            if #[cfg(feature = "relay")] {

                } else {

                    // Yes, clients can have the "relay" feature enabled (unit tests).

                };

            } else {

                let builder =  builder::ChanBuilder::new_client(runtime.clone(), transport);

            }

        };

            #[cfg(feature = "pt-client")]

        );

    /// Launch the periodic daemon tasks required by the manager to function properly.

    ///

    /// Returns a [`TaskHandle`] that can be used to manage

    /// those daemon tasks that poll periodically.

    #[instrument(level = "trace", skip_all)]

            ))

            ))

    /// Build a channel for an incoming stream.

    ///

    /// The `my_addrs` are the IP address(es) that are advertised by the relay in the consensus. We

    /// need to pass them so they can be sent in the NETINFO cell.

    ///

    /// The channel may or may not be authenticated. This method will wait until the channel is

    /// usable, and may return an error if we already have an existing channel to this peer, or if

    /// there are already too many open connections with this peer or subnet (as a dos defence).

    #[cfg(feature = "relay")]

    /// Try to get a suitable channel to the provided `target`,

    /// launching one if one does not exist.

    ///

    /// This function does not guarantee that the returned channel

    /// satisfies all of the properties of `target`. For example if an

    /// existing channel is returned, it might not be connected to any

    /// of the addresses specified in `target`.

    // ^ see https://gitlab.torproject.org/tpo/core/arti/-/issues/2344

    ///

    /// If there is already a channel launch attempt in progress, this

    /// function will wait until that launch is complete, and succeed

    /// or fail depending on its outcome.

    #[instrument(level = "trace", skip_all)]

        let targetinfo = OwnedChanTarget::from_chan_target(target);

        let (chan, provenance) = self.mgr.get_or_launch(targetinfo, usage).await?;

        // Double-check the match to make sure that the RSA identity is

        // what we wanted too.

        chan.check_match(target)

        Ok((chan, provenance))

    /// Return a stream of [`ConnStatus`] events to tell us about changes

    /// in our ability to connect to the internet.

    ///

    /// Note that this stream can be lossy: the caller will not necessarily

    /// observe every event on the stream

    /// Expire all channels that have been unused for too long.

    ///

    /// Return the duration from now until next channel expires.

    /// Notifies the chanmgr to be dormant like dormancy

    /// Reconfigure all channels

            // Since `self.mgr.reconfigure` returns an error type of `Bug` and not

            // `ReconfigureError` (see check below), the reconfigure should only fail due to bugs.

            // This means we can return `Ok` here since there should never be an error with the

            // provided `config` values.

        // Check that `self.mgr.reconfigure` returns an error type of `Bug` (see comment above).

    /// Replace the transport registry with one that may know about

    /// more transports.

    ///

    /// Note that the [`ChannelFactory`](factory::ChannelFactory) instances returned by `ptmgr` are

    /// required to time-out channels that take too long to build.  You'll get

    /// this behavior by default if the factories implement [`ChannelFactory`](factory::ChannelFactory) using

    /// [`transport::proxied::ExternalProxyPlugin`], which `tor-ptmgr` does.

    #[cfg(feature = "pt-client")]

    /// Replace the relay identities used for building new channels.

    ///

    /// This rebuilds the internal channel builder with the provided `identities`, which includes a

    /// new TLS cert and key. Existing channels are not affected, only newly created channels will

    /// use the new identities.

    #[cfg(feature = "relay")]

            }

    /// Try to create a new, unmanaged channel to `target`.

    ///

    /// Unlike [`get_or_launch`](ChanMgr::get_or_launch), this function always

    /// creates a new channel, never retries transient failure, and does not

    /// register this channel with the `ChanMgr`.

    ///

    /// Generally you should not use this function; `get_or_launch` is usually a

    /// better choice.  This function is the right choice if, for whatever

    /// reason, you need to manage the lifetime of the channel you create, and

    /// make sure that no other code with access to this `ChanMgr` will be able

    /// to use the channel.

    #[cfg(feature = "experimental-api")]

    #[instrument(level = "trace", skip_all)]

        use factory::ChannelFactory as _;

        let target = target.to_owned();

        self.mgr

            .channels

            .builder()

            .connect_via_transport(&target, self.mgr.reporter.clone(), memquota)

            .await

    /// Watch for things that ought to change the configuration of all channels in the client

    ///

    /// Currently this handles enabling and disabling channel padding.

    ///

    /// This is a daemon task that runs indefinitely in the background,

    /// and exits when we find that `chanmgr` is dropped.

    #[instrument(level = "trace", skip_all)]

        use tor_netdir::DirEvent as DE;

        let mut netdir_stream = netdir.events().fuse();

        let netdir = {

            let weak = Arc::downgrade(&netdir);

            drop(netdir);

            weak

        };

            loop {

                    }

                }

            }

        .await;

        debug!(

            "continually_update_channels_config: shutting down: {}",

            termination_reason.void_unwrap_err()

        );

    /// Periodically expire any channels that have been unused beyond

    /// the maximum duration allowed.

    ///

    /// Exist when we find that `chanmgr` is dropped

    ///

    /// This is a daemon task that runs indefinitely in the background

    #[instrument(level = "trace", skip_all)]

        while sched.next().await.is_some() {

            let Some(cm) = Weak::upgrade(&chanmgr) else {

                // channel manager is closed.

                return;

            };

            let delay = cm.expire_channels();

            // This will sometimes be an underestimate, but it's no big deal; we just sleep some more.

            sched.fire_in(delay);

        }

}

#[cfg(feature = "relay")]

#[async_trait]

impl<R: Runtime> ChannelProvider for ChanMgr<R> {

    type BuildSpec = OwnedChanTarget;

        use tor_error::into_internal;

                // Send back the channel.

}