added specific error types for keepalive and inactivity timeouts

Author: Eugeny

russh/src/client/mod.rs

@@ -818,15 +818,15 @@ impl Session {
                 () = &mut keepalive_timer => {
                     if self.common.config.keepalive_max != 0 && self.common.alive_timeouts > self.common.config.keepalive_max {
                         debug!("Timeout, server not responding to keepalives");
-                        break
+                        return Err(crate::Error::KeepaliveTimeout);
                     }
                     self.common.alive_timeouts = self.common.alive_timeouts.saturating_add(1);
                     self.send_keepalive(true);
                     sent_keepalive = true;
                 }
                 () = &mut inactivity_timer => {
                     debug!("timeout");
-                    break
+                    return Err(crate::Error::InactivityTimeout);
                 }
                 msg = self.receiver.recv(), if !self.is_rekeying() => {
                     match msg {

russh/src/lib.rs

@@ -249,6 +249,14 @@ pub enum Error {
     #[error("Connection timeout")]
     ConnectionTimeout,
 
+    /// Keepalive timeout.
+    #[error("Keepalive timeout")]
+    KeepaliveTimeout,
+
+    /// Inactivity timeout.
+    #[error("Inactivity timeout")]
+    InactivityTimeout,
+
     /// Missing authentication method.
     #[error("No authentication method")]
     NoAuthMethod,

russh/src/server/session.rs

@@ -447,15 +447,15 @@ impl Session {
                 () = &mut keepalive_timer => {
                     if self.common.config.keepalive_max != 0 && self.common.alive_timeouts > self.common.config.keepalive_max {
                         debug!("Timeout, client not responding to keepalives");
-                        break
+                        return Err(crate::Error::KeepaliveTimeout);
                     }
                     self.common.alive_timeouts = self.common.alive_timeouts.saturating_add(1);
                     sent_keepalive = true;
                     self.keepalive_request();
                 }
                 () = &mut inactivity_timer => {
                     debug!("timeout");
-                    break
+                    return Err(crate::Error::InactivityTimeout);
                 }
                 msg = self.receiver.recv(), if !self.is_rekeying() => {
                     match msg {