restrict keepalive by server

src/etcp_connections.c

@@ -265,7 +265,12 @@ static void keepalive_timer_cb(void* arg) {
     }
 
     // Send keepalive only if no packets were sent since last tick
-    if (!link->pkt_sent_since_keepalive) etcp_link_send_keepalive(link);
+    if (!link->pkt_sent_since_keepalive) {
+      if (link->is_server) {
+        if (link->recv_keepalive) etcp_link_send_keepalive(link);// сервер прекращает слать keepalive если линк потерян (ждём keepalive клиента)
+        }
+      else etcp_link_send_keepalive(link);
+      }
     link->pkt_sent_since_keepalive = 0;
 
 restart_timer: