better online/offline status handling

oml/utils.py

@@ -346,3 +346,16 @@ def open_folder(folder=None, path=None):
     else:
         logger.debug('unsupported platform %s', sys.platform)
     subprocess.Popen(cmd, close_fds=True)
+
+def can_connect_dns(host="8.8.8.8", port=53):
+    """
+        host: 8.8.8.8 (google-public-dns-a.google.com)
+        port: 53/tcp
+    """
+    try:
+        socket.setdefaulttimeout(1)
+        socket.socket(socket.AF_INET, socket.SOCK_STREAM).connect((host, port))
+        return True
+    except:
+        pass
+    return False