fix: noise-read in UoT handshake (single attempt, 4s timeout); add TCP rate limiter against bots

ostp-client/src/bridge.rs

@@ -886,15 +886,21 @@ impl Bridge {
         let mut size = 0;
         let mut success = false;
 
-        // Retransmit handshake up to 4 times with 1200ms timeout to survive packet loss on mobile
-        for attempt in 0..4 {
+        // For UoT: TCP is reliable so we don't retry on the same connection.
+        // Multiple retries would cause stale Noise responses to queue in the mpsc channel
+        // and break the Noise state machine (noise-read error).
+        // For UDP: retry up to 4x with 1200ms timeout to survive packet loss.
+        let is_uot = matches!(socket, crate::transport::Transport::Uot { .. });
+        let (attempt_limit, attempt_timeout_ms) = if is_uot { (1, 4000) } else { (4, 1200) };
+
+        for attempt in 0..attempt_limit {
             if attempt > 0 {
                 tx.send(UiEvent::Log(format!("Handshake attempt {} lost. Retransmitting...", attempt))).await.ok();
             }
             send_datagram(&socket, &handshake_frame, self.turn_enabled).await?;
             self.metrics.bytes_sent.fetch_add(handshake_frame.len() as u64, Ordering::Relaxed);
 
-            match timeout(Duration::from_millis(1200), socket.recv(&mut buf)).await {
+            match timeout(Duration::from_millis(attempt_timeout_ms), socket.recv(&mut buf)).await {
                 Ok(Ok(n)) => {
                     size = n;
                     success = true;

ostp-server/src/lib.rs

@@ -278,8 +278,37 @@ async fn run_server_loop(
         tokio::spawn(async move {
             if let Ok(listener) = tokio::net::TcpListener::bind(&addr).await {
                 tracing::info!("TCP (UoT) listener bound to {}", addr);
+
+                // Rate limiter: track connection attempts per IP
+                // Map<IP, (count, window_start)>
+                let rate_map: std::sync::Arc<tokio::sync::Mutex<std::collections::HashMap<std::net::IpAddr, (u32, std::time::Instant)>>> =
+                    std::sync::Arc::new(tokio::sync::Mutex::new(std::collections::HashMap::new()));
+                const RATE_WINDOW_SECS: u64 = 10;
+                const RATE_MAX_CONNS: u32 = 10;
+
                 loop {
                     if let Ok((stream, peer_addr)) = listener.accept().await {
+                        // Rate limit check
+                        let peer_ip = peer_addr.ip();
+                        let allowed = {
+                            let mut map = rate_map.lock().await;
+                            let now = std::time::Instant::now();
+                            let entry = map.entry(peer_ip).or_insert((0, now));
+                            if now.duration_since(entry.1).as_secs() >= RATE_WINDOW_SECS {
+                                // Reset window
+                                *entry = (1, now);
+                                true
+                            } else {
+                                entry.0 += 1;
+                                entry.0 <= RATE_MAX_CONNS
+                            }
+                        };
+
+                        if !allowed {
+                            tracing::debug!("UoT rate limit exceeded for {}, dropping connection", peer_ip);
+                            continue;
+                        }
+
                         let tm = tcp_map_clone.clone();
                         let keys = shared_keys_clone.clone();
                         let tx = udp_tx_clone.clone();