abstract_tcp_server2: fix timeout on exit

When closing connections due to exiting, the IO service is
already gone, so the data exchange needed for a gracious SSL
shutdown cannot happen. We just close the socket in that case.

contrib/epee/include/net/abstract_tcp_server2.h

@@ -93,11 +93,12 @@ namespace net_utils
     struct shared_state : connection_basic_shared_state
     {
       shared_state()
-        : connection_basic_shared_state(), pfilter(nullptr), config()
+        : connection_basic_shared_state(), pfilter(nullptr), config(), stop_signal_sent(false)
       {}
 
       i_connection_filter* pfilter;
       typename t_protocol_handler::config_type config;
+      bool stop_signal_sent;
     };
 
     /// Construct a connection with the given io_service.

contrib/epee/include/net/abstract_tcp_server2.inl

@@ -762,7 +762,11 @@ PRAGMA_WARNING_DISABLE_VS(4355)
     m_timer.cancel();
     boost::system::error_code ignored_ec;
     if (m_ssl_support == epee::net_utils::ssl_support_t::e_ssl_support_enabled)
-      socket_.shutdown(ignored_ec);
+    {
+      const shared_state &state = static_cast<const shared_state&>(get_state());
+      if (!state.stop_signal_sent)
+        socket_.shutdown(ignored_ec);
+    }
     socket().shutdown(boost::asio::ip::tcp::socket::shutdown_both, ignored_ec);
     if (!m_host.empty())
     {
@@ -1130,6 +1134,8 @@ POP_WARNINGS
   void boosted_tcp_server<t_protocol_handler>::send_stop_signal()
   {
     m_stop_signal_sent = true;
+    typename connection<t_protocol_handler>::shared_state *state = static_cast<typename connection<t_protocol_handler>::shared_state*>(m_state.get());
+    state->stop_signal_sent = true;
     TRY_ENTRY();
     connections_mutex.lock();
     for (auto &c: connections_)