Session: force ack when we received unknown answer

td/mtproto/SessionConnection.cpp

@@ -838,6 +838,12 @@ std::pair<uint64, BufferSlice> SessionConnection::encrypted_bind(int64 perm_key,
   return std::make_pair(query.message_id, packet.as_buffer_slice());
 }
 
+void SessionConnection::force_ack() {
+  if (!to_ack_.empty()) {
+    send_before(Time::now_cached());
+  }
+}
+
 void SessionConnection::send_ack(uint64 message_id) {
   VLOG(mtproto) << "Send ack: [msg_id:" << format::as_hex(message_id) << "]";
   if (to_ack_.empty()) {

td/mtproto/SessionConnection.h

@@ -91,6 +91,7 @@ class SessionConnection final
   void destroy_key();
 
   void set_online(bool online_flag, bool is_main);
+  void force_ack();
 
   class Callback {
    public:

td/telegram/net/Session.cpp

@@ -871,6 +871,7 @@ void Session::on_message_result_error(uint64 id, int error_code, string message)
   }
   auto it = sent_queries_.find(id);
   if (it == sent_queries_.end()) {
+    current_info_->connection_->force_ack();
     return;
   }