darkfi/src/net/acceptor.rs

use async_std::sync::Arc;
use std::{env, fs};

use log::{error, info};
use smol::Executor;
use url::Url;

use crate::{
    system::{StoppableTask, StoppableTaskPtr, Subscriber, SubscriberPtr, Subscription},
    Error, Result,
};

use super::{
    Channel, ChannelPtr, TcpTransport, TorTransport, Transport, TransportListener, TransportName,
};

/// Atomic pointer to Acceptor class.
pub type AcceptorPtr = Arc<Acceptor>;

/// Create inbound socket connections.
pub struct Acceptor {
    channel_subscriber: SubscriberPtr<Result<ChannelPtr>>,
    task: StoppableTaskPtr,
}

impl Acceptor {
    /// Create new Acceptor object.
    pub fn new() -> Arc<Self> {
        Arc::new(Self { channel_subscriber: Subscriber::new(), task: StoppableTask::new() })
    }
    /// Start accepting inbound socket connections. Creates a listener to start
    /// listening on a local socket address. Then runs an accept loop in a new
    /// thread, erroring if a connection problem occurs.
    pub async fn start(
        self: Arc<Self>,
        accept_url: Url,
        executor: Arc<Executor<'_>>,
    ) -> Result<()> {
        let transport_name = TransportName::try_from(accept_url.clone())?;

        macro_rules! accept {
            ($listener:expr, $transport:expr, $upgrade:expr) => {{
                if let Err(err) = $listener {
                    error!("Setup for {} failed: {}", accept_url, err);
                    return Err(Error::BindFailed(accept_url.as_str().into()))
                }

                let listener = $listener?.await;

                if let Err(err) = listener {
                    error!("Bind listener to {} failed: {}", accept_url, err);
                    return Err(Error::BindFailed(accept_url.as_str().into()))
                }

                let listener = listener?;

                match $upgrade {
                    None => {
                        self.accept(Box::new(listener), executor);
                    }
                    Some(u) if u == "tls" => {
                        let tls_listener = $transport.upgrade_listener(listener)?.await?;
                        self.accept(Box::new(tls_listener), executor);
                    }
                    Some(u) => return Err(Error::UnsupportedTransportUpgrade(u)),
                }
            }};
        }

        match transport_name {
            TransportName::Tcp(upgrade) => {
                let transport = TcpTransport::new(None, 1024);
                let listener = transport.listen_on(accept_url.clone());
                accept!(listener, transport, upgrade);
            }
            TransportName::Tor(upgrade) => {
                let socks5_url = Url::parse(
                    &env::var("DARKFI_TOR_SOCKS5_URL")
                        .unwrap_or_else(|_| "socks5://127.0.0.1:9050".to_string()),
                )?;

                let torc_url = Url::parse(
                    &env::var("DARKFI_TOR_CONTROL_URL")
                        .unwrap_or_else(|_| "tcp://127.0.0.1:9051".to_string()),
                )?;

                let auth_cookie = env::var("DARKFI_TOR_COOKIE");

                if auth_cookie.is_err() {
                    return Err(Error::TorError(
                            "Please set the env var DARKFI_TOR_COOKIE to the configured tor cookie file. \
                    For example: \
                    \'export DARKFI_TOR_COOKIE=\"/var/lib/tor/control_auth_cookie\"\'".to_string(),
                    ))
                }

                let auth_cookie = auth_cookie.unwrap();

                let auth_cookie = hex::encode(&fs::read(auth_cookie).unwrap());

                let transport = TorTransport::new(socks5_url, Some((torc_url, auth_cookie)))?;

                // generate EHS pointing to local address
                let hurl = transport.create_ehs(accept_url.clone())?;

                info!("EHS TOR: {}", hurl.to_string());

                let listener = transport.clone().listen_on(accept_url.clone());

                accept!(listener, transport, upgrade);
            }
            _ => unimplemented!(),
        }
        Ok(())
    }

    /// Stop accepting inbound socket connections.
    pub async fn stop(&self) {
        // Send stop signal
        self.task.stop().await;
    }

    /// Start receiving network messages.
    pub async fn subscribe(self: Arc<Self>) -> Subscription<Result<ChannelPtr>> {
        self.channel_subscriber.clone().subscribe().await
    }

    /// Run the accept loop in a new thread and error if a connection problem
    /// occurs.
    fn accept(self: Arc<Self>, listener: Box<dyn TransportListener>, executor: Arc<Executor<'_>>) {
        let self2 = self.clone();
        self.task.clone().start(
            self.clone().run_accept_loop(listener),
            |result| self2.handle_stop(result),
            Error::ServiceStopped,
            executor,
        );
    }

    /// Run the accept loop.
    async fn run_accept_loop(self: Arc<Self>, listener: Box<dyn TransportListener>) -> Result<()> {
        loop {
            let (stream, peer_addr) = listener.next().await?;
            let channel = Channel::new(stream, peer_addr).await;
            self.channel_subscriber.notify(Ok(channel)).await;
        }
    }

    /// Handles network errors. Panics if error passes silently, otherwise
    /// broadcasts the error.
    async fn handle_stop(self: Arc<Self>, result: Result<()>) {
        match result {
            Ok(()) => panic!("Acceptor task should never complete without error status"),
            Err(err) => {
                // Send this error to all channel subscribers
                let result = Err(err);
                self.channel_subscriber.notify(result).await;
            }
        }
    }
}