added Server::handle_session_error and session closure logging

russh/src/client/encrypted.rs

@@ -306,7 +306,6 @@ impl Session {
                             // write responses
                             enc.client_send_auth_response(&responses)?;
                             return Ok((client, self));
-                        } else {
                         }
 
                         // continue with userauth_pk_ok

russh/src/server/encrypted.rs

@@ -190,7 +190,7 @@ impl Session {
                     handler,
                     &mut enc.write,
                     auth,
-                    &mut self.common.auth_user,
+                    &self.common.auth_user,
                     buf,
                 )
                 .await?;
@@ -530,7 +530,7 @@ async fn read_userauth_info_response<H: Handler + Send>(
     mut handler: H,
     write: &mut CryptoVec,
     auth_request: &mut AuthRequest,
-    user: &mut str,
+    user: &str,
     b: &[u8],
 ) -> Result<(H, bool), H::Error> {
     if let Some(CurrentRequest::KeyboardInteractive { ref submethods }) = auth_request.current {

russh/src/server/kex.rs

@@ -44,6 +44,7 @@ impl KexInit {
                     session_id: self.session_id,
                 })
             } else {
+                debug!("unknown key {:?}", algo.key);
                 return Err(Error::UnknownKey);
             };
 

russh/src/server/mod.rs

@@ -118,7 +118,7 @@ use std::task::{Context, Poll};
 
 use async_trait::async_trait;
 use futures::future::Future;
-use log::error;
+use log::{debug, error};
 use russh_keys::key;
 use tokio::io::{AsyncRead, AsyncWrite, AsyncWriteExt};
 use tokio::net::{TcpListener, ToSocketAddrs};
@@ -619,6 +619,8 @@ pub trait Server {
     type Handler: Handler + Send;
     /// Called when a new client connects.
     fn new_client(&mut self, peer_addr: Option<std::net::SocketAddr>) -> Self::Handler;
+    /// Called when an active connection fails.
+    fn handle_session_error(&mut self, _error: <Self::Handler as Handler>::Error) {}
 }
 
 /// Run a server.
@@ -636,11 +638,44 @@ pub async fn run<H: Server + Send + 'static, A: ToSocketAddrs>(
             config.maximum_packet_size
         );
     }
-    while let Ok((socket, _)) = socket.accept().await {
-        let config = config.clone();
-        let server = server.new_client(socket.peer_addr().ok());
-        tokio::spawn(run_stream(config, socket, server));
+
+    let (error_tx, mut error_rx) = tokio::sync::mpsc::unbounded_channel();
+
+    loop {
+        tokio::select! {
+            accept_result = socket.accept() => {
+                match accept_result {
+                    Ok((socket, _)) => {
+                        let config = config.clone();
+                        let handler = server.new_client(socket.peer_addr().ok());
+                        let error_tx = error_tx.clone();
+                        tokio::spawn(async move {
+                            let session = match run_stream(config, socket, handler).await {
+                                Ok(s) => s,
+                                Err(e) => {
+                                    debug!("Connection setup failed");
+                                    let _ = error_tx.send(e);
+                                    return
+                                }
+                            };
+                            match session.await {
+                                Ok(_) => debug!("Connection closed"),
+                                Err(e) => {
+                                    debug!("Connection closed with error");
+                                    let _ = error_tx.send(e);
+                                }
+                            }
+                        });
+                    }
+                    _ => break,
+                }
+            },
+            Some(error) = error_rx.recv() => {
+                server.handle_session_error(error);
+            }
+        }
     }
+
     Ok(())
 }