rusnel 0.3.1

Rusnel is a fast TCP/UDP tunnel, transported over and encrypted using QUIC protocol. Single executable including both client and server
Documentation 
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use std::sync::atomic::{AtomicUsize, Ordering};

use anyhow::Result;

use quinn::Connection;
use tracing::{debug, error, info, info_span, Instrument};

use crate::common::quic::create_server_endpoint;
use crate::common::remote::{Protocol, RemoteRequest};
use crate::common::socks::tunnel_socks_client;
use crate::common::tcp::{tunnel_tcp_client, tunnel_tcp_server};
use crate::common::tunnel::server_receive_remote_request;
use crate::common::udp::{tunnel_udp_client, tunnel_udp_server};
use crate::ServerConfig;

pub fn run(config: ServerConfig) -> Result<()> {
    tokio::runtime::Runtime::new()?.block_on(run_async(config))
}

pub async fn run_async(config: ServerConfig) -> Result<()> {
    let endpoint = create_server_endpoint(config.host, config.port, &config.tls)?;
    info!("Listening on {}", endpoint.local_addr()?);

    let session_counter = AtomicUsize::new(0);

    while let Some(conn) = endpoint.accept().await {
        let session_id = session_counter.fetch_add(1, Ordering::Relaxed) + 1;
        let span = info_span!("session", id = session_id, remote = %conn.remote_address());

        let fut = handle_client_connection(conn, config.allow_reverse);
        tokio::spawn(
            async move {
                info!("client connected");
                if let Err(e) = fut.await {
                    error!("connection failed: {}", e)
                }
            }
            .instrument(span),
        );
    }
    Ok(())
}

async fn handle_client_connection(conn: quinn::Incoming, allow_reverse: bool) -> Result<()> {
    let connection = conn.await?;

    loop {
        let quic_connection = connection.clone();
        let stream = quic_connection.accept_bi().await;

        let stream = match stream {
            Err(quinn::ConnectionError::ApplicationClosed { .. }) => {
                debug!("client disconnected");
                return Ok(());
            }
            Err(e) => {
                error!("stream error: {}", e);
                return Err(e.into());
            }
            Ok(s) => s,
        };

        let fut = handle_remote_stream(quic_connection, stream, allow_reverse);
        tokio::spawn(async move {
            if let Err(e) = fut.await {
                error!("failed: {}", e);
            }
        });
    }
}

async fn handle_remote_stream(
    quic_connection: Connection,
    (mut send, mut recv): (quinn::SendStream, quinn::RecvStream),
    allow_reverse: bool,
) -> Result<()> {
    let request = server_receive_remote_request(&mut send, &mut recv, allow_reverse).await?;
    let remote_display = request.to_string();

    async {
        info!("tunnel established");

        match request {
            // reverse socks
            RemoteRequest {
                local_host: _,
                local_port: _,
                remote_host: ref remote_host_ref,
                remote_port: 0,
                reversed: true,
                protocol: Protocol::Tcp,
            } if remote_host_ref == "socks" => {
                tunnel_socks_client(quic_connection, request).await?;
            }

            // simple forward TCP
            RemoteRequest {
                local_host: _,
                local_port: _,
                remote_host: _,
                remote_port: _,
                reversed: false,
                protocol: Protocol::Tcp,
            } => {
                tunnel_tcp_server(recv, send, request).await?;
            }

            // simple reverse TCP
            RemoteRequest {
                local_host: _,
                local_port: _,
                remote_host: _,
                remote_port: _,
                reversed: true,
                protocol: Protocol::Tcp,
            } => {
                tunnel_tcp_client(quic_connection, request).await?;
            }

            // simple forward UDP
            RemoteRequest {
                local_host: _,
                local_port: _,
                remote_host: _,
                remote_port: _,
                reversed: false,
                protocol: Protocol::Udp,
            } => {
                tunnel_udp_server(recv, send, request).await?;
            }

            // simple reverse UDP
            RemoteRequest {
                local_host: _,
                local_port: _,
                remote_host: _,
                remote_port: _,
                reversed: true,
                protocol: Protocol::Udp,
            } => {
                tunnel_udp_client(quic_connection, request).await?;
            }
        }

        Ok(())
    }
    .instrument(info_span!("tunnel", remote = %remote_display))
    .await
}