improve reliability of connections

src/connect.rs

@@ -223,6 +223,9 @@ async fn ping_pong(
 ) {
     loop {
         let (buf, len) = ProtoEvent::Ping.into();
+
+        // send 4 pings, at least one must be answered
+        for _ in 0..4 {
             if let Err(e) = conn.send(&buf[..len]).await {
                 log::warn!("{addr}: send error `{e}`, closing connection");
                 let _ = conn.close().await;
@@ -231,6 +234,7 @@ async fn ping_pong(
             log::trace!("PING >->->->->- {addr}");
 
             tokio::time::sleep(Duration::from_millis(500)).await;
+        }
 
         if !ping_response.borrow_mut().remove(&addr) {
             log::warn!("{addr} did not respond, closing connection");