ntp: T4456: support listening on specified interface

When clients only use DHCP for interface addressing we can not bind NTPd to
an address - as it will fail if the address changes. This commit adds support
to bind ntpd to a given interface in addition to a given address.

set system ntp interface <name>

4 files changed, 45 insertions, 5 deletions

diff --git a/data/templates/ntp/ntpd.conf.j2 b/data/templates/ntp/ntpd.conf.j2
index da610051e..8921826fa 100644
--- a/data/templates/ntp/ntpd.conf.j2
+++ b/data/templates/ntp/ntpd.conf.j2
@@ -33,10 +33,17 @@ restrict {{ address | address_from_cidr }} mask {{ address | netmask_from_cidr }
 {%     endfor %}
 {% endif %}
 
-{% if listen_address %}
+{% if listen_address is vyos_defined or interface is vyos_defined %}
 # NTP should listen on configured addresses only
 interface ignore wildcard
-{%     for address in listen_address %}
+{%     if listen_address is vyos_defined %}
+{%         for address in listen_address %}
 interface listen {{ address }}
-{%     endfor %}
+{%         endfor %}
+{%     endif %}
+{%     if interface is vyos_defined %}
+{%         for ifname in interface %}
+interface listen {{ ifname }}
+{%         endfor %}
+{%     endif %}
 {% endif %}
diff --git a/interface-definitions/ntp.xml.in b/interface-definitions/ntp.xml.in
index a518a9def..85636a50f 100644
--- a/interface-definitions/ntp.xml.in
+++ b/interface-definitions/ntp.xml.in
@@ -81,6 +81,7 @@
               </leafNode>
             </children>
           </node>
+          #include <include/generic-interface-multi.xml.i>
           #include <include/listen-address.xml.i>
           #include <include/interface/vrf.xml.i>
         </children>
diff --git a/smoketest/scripts/cli/test_system_ntp.py b/smoketest/scripts/cli/test_system_ntp.py
index e2821687c..a0806acf0 100755
--- a/smoketest/scripts/cli/test_system_ntp.py
+++ b/smoketest/scripts/cli/test_system_ntp.py
@@ -108,5 +108,22 @@ class TestSystemNTP(VyOSUnitTestSHIM.TestCase):
         for listen in listen_address:
             self.assertIn(f'interface listen {listen}', config)
 
+    def test_03_ntp_interface(self):
+        interfaces = ['eth0', 'eth1']
+        for interface in interfaces:
+            self.cli_set(base_path + ['interface', interface])
+
+        servers = ['time1.vyos.net', 'time2.vyos.net']
+        for server in servers:
+            self.cli_set(base_path + ['server', server])
+
+        self.cli_commit()
+
+        # Check generated client address configuration
+        config = read_file(NTP_CONF)
+        self.assertIn('interface ignore wildcard', config)
+        for interface in interfaces:
+            self.assertIn(f'interface listen {interface}', config)
+
 if __name__ == '__main__':
     unittest.main(verbosity=2)
diff --git a/src/conf_mode/ntp.py b/src/conf_mode/ntp.py
index 0d6ec9ace..7be150ed2 100755
--- a/src/conf_mode/ntp.py
+++ b/src/conf_mode/ntp.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (C) 2018-2021 VyOS maintainers and contributors
+# Copyright (C) 2018-2022 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
@@ -18,9 +18,11 @@ import os
 
 from vyos.config import Config
 from vyos.configverify import verify_vrf
-from vyos import ConfigError
+from vyos.configverify import verify_interface_exists
 from vyos.util import call
+from vyos.util import get_interface_config
 from vyos.template import render
+from vyos import ConfigError
 from vyos import airbag
 airbag.enable()
 
@@ -48,6 +50,19 @@ def verify(ntp):
     if 'allow_clients' in ntp and 'server' not in ntp:
         raise ConfigError('NTP server not configured')
 
+    if 'interface' in ntp:
+        # If ntpd should listen on a given interface, ensure it exists
+        for interface in ntp['interface']:
+            verify_interface_exists(interface)
+
+            # If we run in a VRF, our interface must belong to this VRF, too
+            if 'vrf' in ntp:
+                tmp = get_interface_config(interface)
+                vrf_name = ntp['vrf']
+                if 'master' not in tmp or tmp['master'] != vrf_name:
+                    raise ConfigError(f'NTP runs in VRF "{vrf_name}" - "{interface}" '\
+                                      f'does not belong to this VRF!')
+
     verify_vrf(ntp)
     return None