Warn when server has not heard from us (even if we have heard from server)

src/frontend/stmclient.cc

@@ -201,6 +201,7 @@ bool STMClient::process_network_input( void )
   
   /* Now give hints to the overlays */
   overlays.get_notification_engine().server_heard( network->get_latest_remote_state().timestamp );
+  overlays.get_notification_engine().server_acked( network->get_sent_state_acked_timestamp() );
 
   overlays.get_prediction_engine().set_local_frame_acked( network->get_sent_state_acked() );
   overlays.get_prediction_engine().set_send_interval( network->send_interval() );

src/frontend/terminaloverlay.cc

@@ -153,6 +153,7 @@ void ConditionalCursorMove::apply( Framebuffer &fb, uint64_t confirmed_epoch ) c
 
 NotificationEngine::NotificationEngine()
   : last_word_from_server( timestamp() ),
+    last_acked_state( timestamp() ),
     message(),
     message_expiration( -1 )
 {}
@@ -188,15 +189,32 @@ void NotificationEngine::apply( Framebuffer &fb ) const
   /* write message */
   wchar_t tmp[ 128 ];
 
+  /* We want to prefer the "last contact" message if we simply haven't
+     heard from the server in a while, but print the "last reply" message
+     if the problem is uplink-only. */
+
+  double since_heard = (double)(now - last_word_from_server) / 1000.0;
+  double since_ack = (double)(now - last_acked_state) / 1000.0;
+  const char server_message[] = "contact";
+  const char reply_message[] = "reply";
+
+  double time_elapsed = since_heard;
+  const char *explanation = server_message;
+
+  if ( reply_late( now ) && (!server_late( now )) ) {
+    time_elapsed = since_ack;
+    explanation = reply_message;
+  }
+
   if ( message.empty() && (!time_expired) ) {
     return;
   } else if ( message.empty() && time_expired ) {
-    swprintf( tmp, 128, L"mosh: Last contact %.0f seconds ago. [To quit: Ctrl-^ .]", (double)(now - last_word_from_server) / 1000.0 );
+    swprintf( tmp, 128, L"mosh: Last %s %.0f seconds ago. [To quit: Ctrl-^ .]", explanation, time_elapsed );
   } else if ( (!message.empty()) && (!time_expired) ) {
     swprintf( tmp, 128, L"mosh: %ls [To quit: Ctrl-^ .]", message.c_str() );
   } else {
-    swprintf( tmp, 128, L"mosh: %ls (%.0f s without contact.) [To quit: Ctrl-^ .]", message.c_str(),
-	      (double)(now - last_word_from_server) / 1000.0 );
+    swprintf( tmp, 128, L"mosh: %ls (%.0f s without %s.) [To quit: Ctrl-^ .]", message.c_str(),
+	      time_elapsed, explanation );
   }
 
   wstring string_to_draw( tmp );

src/frontend/terminaloverlay.h

@@ -127,16 +127,20 @@ namespace Overlay {
   class NotificationEngine {
   private:
     uint64_t last_word_from_server;
+    uint64_t last_acked_state;
     wstring message;
     uint64_t message_expiration;
 
   public:
-    bool need_countup( uint64_t ts ) const { return ts - last_word_from_server > 6500; }
+    bool server_late( uint64_t ts ) const { return (ts - last_word_from_server) > 6500; }
+    bool reply_late( uint64_t ts ) const { return (ts - last_acked_state) > 10000; }
+    bool need_countup( uint64_t ts ) const { return server_late( ts ) || reply_late( ts ); }
     void adjust_message( void );
     void apply( Framebuffer &fb ) const;
     void set_notification_string( const wstring &s_message, bool permanent = false ) { message = s_message; if ( permanent ) { message_expiration = -1; } else { message_expiration = timestamp() + 1000; } }
     const wstring &get_notification_string( void ) const { return message; }
     void server_heard( uint64_t s_last_word ) { last_word_from_server = s_last_word; }
+    void server_acked( uint64_t s_last_acked ) { last_acked_state = s_last_acked; }
     uint64_t get_message_expiration( void ) const { return message_expiration; }
 
     NotificationEngine();

src/network/networktransport.h

@@ -95,6 +95,7 @@ namespace Network {
 
     void set_send_delay( int new_delay ) { sender.set_send_delay( new_delay ); }
 
+    uint64_t get_sent_state_acked_timestamp( void ) const { return sender.get_sent_state_acked_timestamp(); }
     uint64_t get_sent_state_acked( void ) const { return sender.get_sent_state_acked(); }
     uint64_t get_sent_state_last( void ) const { return sender.get_sent_state_last(); }
 

src/network/transportsender.h

@@ -126,6 +126,7 @@ namespace Network {
     bool get_shutdown_in_progress( void ) const { return shutdown_in_progress; }
     bool get_shutdown_acknowledged( void ) const { return sent_states.front().num == uint64_t(-1); }
     bool get_counterparty_shutdown_acknowledged( void ) const { return fragmenter.last_ack_sent() == uint64_t(-1); }
+    uint64_t get_sent_state_acked_timestamp( void ) const { return sent_states.front().timestamp; }
     uint64_t get_sent_state_acked( void ) const { return sent_states.front().num; }
     uint64_t get_sent_state_last( void ) const { return sent_states.back().num; }