T6121: Extend service config-sync to new sections

Extend `service config-sync` with new sections:
 - LeafNodes: pki, policy, vpn, vrf (syncs the whole sections)
 - Nodes: interfaces, protocols, service (syncs subsections)

In this cae the Node allows to uses the next level section
i.e subsection

For example any of the subsection of the node `interfaces`:
  - set service config-sync section interfaces pseudo-ethernet
  - set service config-sync section interfaces virtual-ethernet

Example of the config:
```
set service config-sync mode 'load'
set service config-sync secondary address '192.0.2.1'
set service config-sync secondary key 'xxx'
set service config-sync section firewall
set service config-sync section interfaces pseudo-ethernet
set service config-sync section interfaces virtual-ethernet
set service config-sync section nat
set service config-sync section nat66
set service config-sync section protocols static
set service config-sync section pki
set service config-sync section vrf
```

2 files changed, 390 insertions, 30 deletions

diff --git a/interface-definitions/service_config-sync.xml.in b/interface-definitions/service_config-sync.xml.in
index 9955acfee..9e9dcdb69 100644
--- a/interface-definitions/service_config-sync.xml.in
+++ b/interface-definitions/service_config-sync.xml.in
@@ -73,30 +73,382 @@
               </constraint>
             </properties>
           </leafNode>
-          <leafNode name="section">
+          <node name="section">
             <properties>
               <help>Section for synchronization</help>
-              <completionHelp>
-                <list>nat nat66 firewall</list>
-              </completionHelp>
-              <valueHelp>
-                <format>nat</format>
-                <description>NAT</description>
-              </valueHelp>
-              <valueHelp>
-                <format>nat66</format>
-                <description>NAT66</description>
-              </valueHelp>
-              <valueHelp>
-                <format>firewall</format>
-                <description>firewall</description>
-              </valueHelp>
-              <constraint>
-                <regex>(nat|nat66|firewall)</regex>
-              </constraint>
-              <multi/>
             </properties>
-          </leafNode>
+            <children>
+              <leafNode name="firewall">
+                <properties>
+                  <help>Firewall</help>
+                  <valueless/>
+                </properties>
+              </leafNode>
+              <node name="interfaces">
+                <properties>
+                  <help>Interfaces</help>
+                </properties>
+                <children>
+                  <leafNode name="bonding">
+                    <properties>
+                      <help>Bonding interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="bridge">
+                    <properties>
+                      <help>Bridge interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="dummy">
+                    <properties>
+                      <help>Dummy interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="ethernet">
+                    <properties>
+                      <help>Ethernet interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="geneve">
+                    <properties>
+                      <help>GENEVE interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="input">
+                    <properties>
+                      <help>Input interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="l2tpv3">
+                    <properties>
+                      <help>L2TPv3 interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="loopback">
+                    <properties>
+                      <help>Loopback interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="macsec">
+                    <properties>
+                      <help>MACsec interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="openvpn">
+                    <properties>
+                      <help>OpenVPN interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="pppoe">
+                    <properties>
+                      <help>PPPoE interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="pseudo-ethernet">
+                    <properties>
+                      <help>Pseudo-Ethernet interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="sstpc">
+                    <properties>
+                      <help>SSTP client interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="tunnel">
+                    <properties>
+                      <help>Tunnel interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="virtual-ethernet">
+                    <properties>
+                      <help>Virtual Ethernet interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="vti">
+                    <properties>
+                      <help>Virtual tunnel interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="vxlan">
+                    <properties>
+                      <help>VXLAN interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="wireguard">
+                    <properties>
+                      <help>Wireguard interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="wireless">
+                    <properties>
+                      <help>Wireless interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="wwan">
+                    <properties>
+                      <help>WWAN interface</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                </children>
+              </node>
+              <leafNode name="nat">
+                <properties>
+                  <help>NAT</help>
+                  <valueless/>
+                </properties>
+              </leafNode>
+              <leafNode name="nat66">
+                <properties>
+                  <help>NAT66</help>
+                  <valueless/>
+                </properties>
+              </leafNode>
+              <leafNode name="pki">
+                <properties>
+                  <help>Public key infrastructure (PKI)</help>
+                  <valueless/>
+                </properties>
+              </leafNode>
+              <leafNode name="policy">
+                <properties>
+                  <help>Routing policy</help>
+                  <valueless/>
+                </properties>
+              </leafNode>
+              <node name="protocols">
+                <properties>
+                  <help>Routing protocols</help>
+                </properties>
+                <children>
+                  <leafNode name="babel">
+                    <properties>
+                      <help>Babel Routing Protocol</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="bfd">
+                    <properties>
+                      <help>Bidirectional Forwarding Detection (BFD)</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="bgp">
+                    <properties>
+                      <help>Border Gateway Protocol (BGP)</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="failover">
+                    <properties>
+                      <help>Failover route</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="igmp-proxy">
+                    <properties>
+                      <help>Internet Group Management Protocol (IGMP) proxy</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="isis">
+                    <properties>
+                      <help>Intermediate System to Intermediate System (IS-IS)</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="mpls">
+                    <properties>
+                      <help>Multiprotocol Label Switching (MPLS)</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="nhrp">
+                    <properties>
+                      <help>Next Hop Resolution Protocol (NHRP) parameters</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="ospf">
+                    <properties>
+                      <help>Open Shortest Path First (OSPF)</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="ospfv3">
+                    <properties>
+                      <help>Open Shortest Path First (OSPF) for IPv6</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="pim">
+                    <properties>
+                      <help>Protocol Independent Multicast (PIM) and IGMP</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="pim6">
+                    <properties>
+                      <help>Protocol Independent Multicast for IPv6 (PIMv6) and MLD</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="rip">
+                    <properties>
+                      <help>Routing Information Protocol (RIP) parameters</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="ripng">
+                    <properties>
+                      <help>Routing Information Protocol (RIPng) parameters</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="rpki">
+                    <properties>
+                      <help>Resource Public Key Infrastructure (RPKI)</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="segment-routing">
+                    <properties>
+                      <help>Segment Routing</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="static">
+                    <properties>
+                      <help>Static Routing</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                </children>
+              </node>
+              <node name="service">
+                <properties>
+                  <help>System services</help>
+                </properties>
+                <children>
+                  <leafNode name="console-server">
+                    <properties>
+                      <help>Serial Console Server</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="dhcp-relay">
+                    <properties>
+                      <help>Host Configuration Protocol (DHCP) relay agent</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="dhcp-server">
+                    <properties>
+                      <help>Dynamic Host Configuration Protocol (DHCP) for DHCP server</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="dhcpv6-relay">
+                    <properties>
+                      <help>DHCPv6 Relay Agent parameters</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="dhcpv6-server">
+                    <properties>
+                      <help>DHCP for IPv6 (DHCPv6) server</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="dns">
+                    <properties>
+                      <help>Domain Name System (DNS) related services</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="lldp">
+                    <properties>
+                      <help>LLDP settings</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="mdns">
+                    <properties>
+                      <help>Multicast DNS (mDNS) parameters</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="monitoring">
+                    <properties>
+                      <help>Monitoring services</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="ndp-proxy">
+                    <properties>
+                      <help>Neighbor Discovery Protocol (NDP) Proxy</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="ntp">
+                    <properties>
+                      <help>Network Time Protocol (NTP) configuration</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="snmp">
+                    <properties>
+                      <help>Simple Network Management Protocol (SNMP)</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="tftp-server">
+                    <properties>
+                      <help>Trivial File Transfer Protocol (TFTP) server</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="webproxy">
+                    <properties>
+                      <help>Webproxy service settings</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
+                </children>
+              </node>
+              <leafNode name="vpn">
+                <properties>
+                  <help>Virtual Private Network (VPN)</help>
+                  <valueless/>
+                </properties>
+              </leafNode>
+              <leafNode name="vrf">
+                <properties>
+                  <help>Virtual Routing and Forwarding</help>
+                  <valueless/>
+                </properties>
+              </leafNode>
+            </children>
+          </node>
         </children>
       </node>
     </children>
diff --git a/src/helpers/vyos_config_sync.py b/src/helpers/vyos_config_sync.py
index 7cfa8fe88..572fea61f 100755
--- a/src/helpers/vyos_config_sync.py
+++ b/src/helpers/vyos_config_sync.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (C) 2023 VyOS maintainers and contributors
+# Copyright (C) 2023-2024 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
@@ -60,6 +60,7 @@ def post_request(url: str,
     return response
 
 
+
 def retrieve_config(section: str = None) -> Optional[Dict[str, Any]]:
     """Retrieves the configuration from the local server.
 
@@ -71,8 +72,6 @@ def retrieve_config(section: str = None) -> Optional[Dict[str, Any]]:
     """
     if section is None:
         section = []
-    else:
-        section = section.split()
 
     conf = Config()
     config = conf.get_config_dict(section, get_first_key=True)
@@ -101,8 +100,6 @@ def set_remote_config(
 
     if path is None:
         path = []
-    else:
-        path = path.split()
     headers = {'Content-Type': 'application/json'}
 
     # Disable the InsecureRequestWarning
@@ -127,17 +124,16 @@ def set_remote_config(
 
 def is_section_revised(section: str) -> bool:
     from vyos.config_mgmt import is_node_revised
-    return is_node_revised([section])
+    return is_node_revised(section)
 
 
 def config_sync(secondary_address: str,
                 secondary_key: str,
-                sections: List[str],
+                sections: List[list],
                 mode: str):
     """Retrieve a config section from primary router in JSON format and send it to
        secondary router
     """
-    # Config sync only if sections changed
     if not any(map(is_section_revised, sections)):
         return
 
@@ -188,5 +184,17 @@ if __name__ == '__main__':
             "Missing required configuration data for config synchronization.")
         exit(0)
 
+    # Generate list_sections of sections/subsections
+    # [
+    #   ['interfaces', 'pseudo-ethernet'], ['interfaces', 'virtual-ethernet'], ['nat'], ['nat66']
+    # ]
+    list_sections = []
+    for section, subsections in sections.items():
+        if subsections:
+            for subsection in subsections:
+                list_sections.append([section, subsection])
+        else:
+            list_sections.append([section])
+
     config_sync(secondary_address, secondary_key,
-                sections, mode)
+                list_sections, mode)