net/bridge.py: refactor module

Refactor the utils_net.py:
1. Split net_driver/bridge module from utils_net module.

Signed-off-by: Houqi (Nick) Zuo <[email protected]>

virttest/vt_utils/net_driver/bridge.py

@@ -0,0 +1,68 @@
+# Library for the bridge address related functions.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; specifically version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+#
+# See LICENSE for more details.
+#
+# Copyright: Red Hat (c) 2024 and Avocado contributors
+# Author: Houqi Zuo <[email protected]>
+import json
+
+from avocado.utils import process
+
+from virttest.vt_utils.net import interface
+
+
+def find_bridge_name(iface):
+    """
+    Finds bridge name based in the interface name.
+
+    :param iface: The interface name.
+    :type iface: String.
+
+    :return: The bridge name. If not found, return None.
+    :rtype: String or None.
+    """
+    cmd = "bridge -json link"
+    cmd_obj = process.run(cmd, shell=True)
+    output = cmd_obj.stdout_text.strip()
+    bridge_info = json.loads(output)
+    for bridge in bridge_info:
+        if bridge["ifname"] in (iface,):
+            return bridge["master"]
+    return None
+
+
+def add_to_bridge(ifname, brname):
+    """
+    Add the interface into the bridge.
+
+    :param ifname: The interface name.
+    :type ifname: String.
+
+    :param brname: The bridge name.
+    :type brname: String.
+    """
+    # To add an interface into the bridge, its state must be up.
+    interface.bring_up_ifname(ifname)
+    cmd_add_to_bridge = "ip link set %s master %s" % (ifname, brname)
+    process.run(cmd_add_to_bridge, shell=True)
+
+
+def del_from_bridge(ifname):
+    """
+    Delete the interface from the bridge.
+    NOTE: Bringing the interface down is excluded at this function.
+          You may call the function about bringing interface down after del_from_bridge().
+
+    :param ifname: The interface name.
+    :type ifname: String.
+    """
+    cmd = "ip link set %s nomaster" % ifname
+    process.run(cmd, shell=True)