feat: better error message when adding DBs (#13601)

* WIP

* Adding tests

* Add unit tests

* Show error message

* Fix lint

* Fix after rebase

superset/utils/network.py

@@ -0,0 +1,71 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+import platform
+import socket
+import subprocess
+
+PORT_TIMEOUT = 5
+PING_TIMEOUT = 5
+
+
+def is_port_open(host: str, port: int) -> bool:
+    """
+    Test if a given port in a host is open.
+    """
+    # pylint: disable=invalid-name
+    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    s.settimeout(PORT_TIMEOUT)
+    try:
+        s.connect((host, int(port)))
+        s.shutdown(socket.SHUT_RDWR)
+        return True
+    except socket.error:
+        return False
+    finally:
+        s.close()
+
+    return False
+
+
+def is_hostname_valid(host: str) -> bool:
+    """
+    Test if a given hostname can be resolved.
+    """
+    try:
+        socket.gethostbyname(host)
+        return True
+    except socket.gaierror:
+        return False
+
+    return False
+
+
+def is_host_up(host: str) -> bool:
+    """
+    Ping a host to see if it's up.
+
+    Note that if we don't get a response the host might still be up,
+    since many firewalls block ICMP packets.
+    """
+    param = "-n" if platform.system().lower() == "windows" else "-c"
+    command = ["ping", param, "1", host]
+    try:
+        output = subprocess.call(command, timeout=PING_TIMEOUT)
+    except subprocess.TimeoutExpired:
+        return False
+
+    return output == 0