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use async_std::io; use async_std::net::{SocketAddr, TcpListener, TcpStream}; use async_std::prelude::*; use async_std::sync::channel; use async_std::sync::Arc; use async_std::task; use std::net::Shutdown; const BUFFER_LEN: usize = 65535; const CHANNEL_LEN: usize = 1024; type Sender = async_std::sync::Sender<Arc<Vec<u8>>>; type Receiver = async_std::sync::Receiver<Arc<Vec<u8>>>; pub async fn accept_loop( listen_addr: SocketAddr, target_addr: SocketAddr, observer_addrs: Vec<SocketAddr>, ) -> io::Result<()> { let target_addr = Arc::new(target_addr); let observer_addrs = Arc::new(observer_addrs); let listener = TcpListener::bind(listen_addr).await?; let mut incoming = listener.incoming(); while let Some(client_stream) = incoming.next().await { if let Ok(client_stream) = client_stream { let target_addr = target_addr.clone(); let observer_addrs = observer_addrs.clone(); task::spawn(async move { let _ = proxy_loop(client_stream, target_addr, observer_addrs).await; }); } } Ok(()) } async fn proxy_loop( client_stream: TcpStream, target_addr: Arc<SocketAddr>, observer_addrs: Arc<Vec<SocketAddr>>, ) -> io::Result<()> { task::spawn(async move { let mut channels: Vec<Sender> = Vec::with_capacity(observer_addrs.len() + 1); for observer_addr in observer_addrs.iter() { let (client_sender, observer_receiver) = channel(CHANNEL_LEN); channels.push(client_sender); let observer_addr = *observer_addr; task::spawn(async move { let _ = observer_loop(observer_addr, observer_receiver).await; }); } let client_stream = Arc::new(client_stream); let (client_reader, client_writer) = (client_stream.clone(), client_stream); let (client_sender, target_receiver) = channel(CHANNEL_LEN); channels.push(client_sender); task::spawn(async move { let _ = target_loop(target_addr, target_receiver, client_writer).await; }); task::spawn(async move { let _ = client_read_loop(client_reader, channels).await; }); }); Ok(()) } async fn target_loop( target_addr: Arc<SocketAddr>, client_broadcast_receiver: Receiver, client_stream: Arc<TcpStream>, ) -> io::Result<()> { let target_stream = TcpStream::connect(*target_addr).await?; let target_stream = Arc::new(target_stream); let (target_reader, target_writer) = (target_stream.clone(), target_stream); task::spawn(async move { let _ = target_read_loop(target_reader, client_stream).await; }); let mut target_writer = &*target_writer; while let Some(data) = client_broadcast_receiver.recv().await { target_writer.write_all(&data).await?; } target_writer.shutdown(Shutdown::Write)?; Ok(()) } async fn observer_loop( observer_addr: SocketAddr, client_broadcast_receiver: Receiver, ) -> io::Result<()> { let mut observer_stream = TcpStream::connect(observer_addr).await?; while let Some(data) = client_broadcast_receiver.recv().await { observer_stream.write_all(&data).await?; } Ok(()) } async fn client_read_loop(client_stream: Arc<TcpStream>, txs: Vec<Sender>) -> io::Result<()> { let mut client_stream = &*client_stream; let mut buf = vec![0u8; BUFFER_LEN]; loop { let n = client_stream.read(&mut buf).await?; if n == 0 { break; } let data = Arc::new(buf[..n].to_vec()); for tx in txs.iter() { let tx = tx.clone(); let data = data.clone(); task::spawn(async move { tx.send(data.clone()).await; }); } } Ok(()) } async fn target_read_loop( target_stream: Arc<TcpStream>, client_stream: Arc<TcpStream>, ) -> io::Result<()> { let mut client_stream = &*client_stream; let mut target_stream = &*target_stream; let mut buf = vec![0u8; BUFFER_LEN]; loop { let n = target_stream.read(&mut buf).await?; if n == 0 { client_stream.shutdown(Shutdown::Write)?; break; } client_stream.write_all(&buf[..n]).await?; } Ok(()) }