#![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)]

#![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

//! <!-- @@ 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::select_biased;

use futures::task::SpawnExt;

use futures::StreamExt;

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::{params::NetParameters, NetDirProvider};

use tor_proto::channel::Channel;

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

use tor_proto::memquota::ChannelAccount;

use tor_proto::memquota::ToplevelAccount;

use tracing::debug;

use void::{ResultVoidErrExt, Void};

pub use err::Error;

pub use config::{ChannelConfig, ChannelConfigBuilder};

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.  For a

/// much lower-level API, see [`tor_proto::channel::ChannelBuilder`].)

///

/// 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,

    /// This currently isn't actually used, but we're keeping a PhantomData here

    /// since probably we'll want it again, sooner or later.

    runtime: std::marker::PhantomData<fn(R) -> 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`.

    /// 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.

    /// Build a channel for an incoming stream.

    ///

    /// 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.

    ///

    /// 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.

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

        // what we wanted too.

    /// 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.

    /// 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")]

    /// 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")]

        use factory::ChannelFactory as _;

    /// 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.

        use tor_netdir::DirEvent as DE;

        };

            loop {

                    }

                }

            }

        );

    /// 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

                // channel manager is closed.

            };

        }

}