T6350: CGNAT add op-mode to show allocation

Add op-mode command `show nat cgnat allocation` to get CGNAT
allocations (internal address, external address, port-range)

1 files changed, 75 insertions, 0 deletions

diff --git a/src/op_mode/cgnat.py b/src/op_mode/cgnat.py
new file mode 100755
index 000000000..a98269a15
--- /dev/null
+++ b/src/op_mode/cgnat.py
@@ -0,0 +1,75 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2024 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# 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 the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import json
+import sys
+import typing
+
+from tabulate import tabulate
+
+import vyos.opmode
+
+from vyos.configquery import ConfigTreeQuery
+from vyos.utils.process import cmd
+
+CGNAT_TABLE = 'cgnat'
+
+
+def _get_raw_data():
+    """ Get CGNAT dictionary
+    """
+    cmd_output = cmd(f'nft --json list table ip {CGNAT_TABLE}')
+    data = json.loads(cmd_output)
+    return data
+
+
+def _get_formatted_output(data):
+    elements = data['nftables'][2]['map']['elem']
+    allocations = []
+    for elem in elements:
+        internal = elem[0]  # internal
+        external = elem[1]['concat'][0]  # external
+        start_port = elem[1]['concat'][1]['range'][0]
+        end_port = elem[1]['concat'][1]['range'][1]
+        port_range = f'{start_port}-{end_port}'
+        allocations.append((internal, external, port_range))
+
+    headers = ['Internal IP', 'External IP', 'Port range']
+    output = tabulate(allocations, headers, numalign="left")
+    return output
+
+
+def show_allocation(raw: bool):
+    config = ConfigTreeQuery()
+    if not config.exists('nat cgnat'):
+        raise vyos.opmode.UnconfiguredSubsystem('CGNAT is not configured')
+
+    if raw:
+        return _get_raw_data()
+
+    else:
+        raw_data = _get_raw_data()
+        return _get_formatted_output(raw_data)
+
+
+if __name__ == '__main__':
+    try:
+        res = vyos.opmode.run(sys.modules[__name__])
+        if res:
+            print(res)
+    except (ValueError, vyos.opmode.Error) as e:
+        print(e)
+        sys.exit(1)