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use std::net::SocketAddr;
use std::sync::Arc;
use std::time::Duration;
use anyhow::Result;
use dashmap::DashMap;
use tokio::io::BufReader;
use tokio::net::{TcpListener, TcpStream};
use tokio::time::{sleep, timeout};
use tracing::{info, info_span, warn, Instrument};
use uuid::Uuid;
use crate::auth::Authenticator;
use crate::shared::{
proxy, recv_json_timeout, send_json, ClientMessage, ServerMessage, CONTROL_PORT,
};
pub struct Server {
min_port: u16,
auth: Option<Authenticator>,
conns: Arc<DashMap<Uuid, TcpStream>>,
}
impl Server {
pub fn new(min_port: u16, secret: Option<&str>) -> Self {
Server {
min_port,
conns: Arc::new(DashMap::new()),
auth: secret.map(Authenticator::new),
}
}
pub async fn listen(self) -> Result<()> {
let this = Arc::new(self);
let addr = SocketAddr::from(([0, 0, 0, 0], CONTROL_PORT));
let listener = TcpListener::bind(&addr).await?;
info!(?addr, "server listening");
loop {
let (stream, addr) = listener.accept().await?;
let this = Arc::clone(&this);
tokio::spawn(
async move {
info!("incoming connection");
if let Err(err) = this.handle_connection(stream).await {
warn!(%err, "connection exited with error");
} else {
info!("connection exited");
}
}
.instrument(info_span!("control", ?addr)),
);
}
}
async fn handle_connection(&self, stream: TcpStream) -> Result<()> {
let mut stream = BufReader::new(stream);
if let Some(auth) = &self.auth {
if let Err(err) = auth.server_handshake(&mut stream).await {
warn!(%err, "server handshake failed");
send_json(&mut stream, ServerMessage::Error(err.to_string())).await?;
return Ok(());
}
}
match recv_json_timeout(&mut stream).await? {
Some(ClientMessage::Authenticate(_)) => {
warn!("unexpected authenticate");
Ok(())
}
Some(ClientMessage::Hello(port)) => {
if port != 0 && port < self.min_port {
warn!(?port, "client port number too low");
return Ok(());
}
info!(?port, "new client");
let listener = match TcpListener::bind(("::", port)).await {
Ok(listener) => listener,
Err(_) => {
warn!(?port, "could not bind to local port");
send_json(
&mut stream,
ServerMessage::Error("port already in use".into()),
)
.await?;
return Ok(());
}
};
let port = listener.local_addr()?.port();
send_json(&mut stream, ServerMessage::Hello(port)).await?;
loop {
if send_json(&mut stream, ServerMessage::Heartbeat)
.await
.is_err()
{
return Ok(());
}
const TIMEOUT: Duration = Duration::from_millis(500);
if let Ok(result) = timeout(TIMEOUT, listener.accept()).await {
let (stream2, addr) = result?;
info!(?addr, ?port, "new connection");
let id = Uuid::new_v4();
let conns = Arc::clone(&self.conns);
conns.insert(id, stream2);
tokio::spawn(async move {
sleep(Duration::from_secs(10)).await;
if conns.remove(&id).is_some() {
warn!(%id, "removed stale connection");
}
});
send_json(&mut stream, ServerMessage::Connection(id)).await?;
}
}
}
Some(ClientMessage::Accept(id)) => {
info!(%id, "forwarding connection");
match self.conns.remove(&id) {
Some((_, stream2)) => proxy(stream, stream2).await?,
None => warn!(%id, "missing connection"),
}
Ok(())
}
None => {
warn!("unexpected EOF");
Ok(())
}
}
}
}
impl Default for Server {
fn default() -> Self {
Server::new(1024, None)
}
}