dhcpv6-pd: T2677: optimize CLI interface for PD configuration

The current CLI did not support multiple prefix-delegations per interface. Some
ISPs only send one /64 to a client per prefix-delegation request, but they
allow the customer to request multiple prefixes.

The 'dhcpv6-options prefix-delegation' node has been renamed and converted to a
tag node named 'dhcpv6-options pd'. The tag node specifies a PD request (>=0).

In the past the user needed to know what prefix will be assigned and required
to calculate the sla-len by himself. The 'sla-len' node was dropped and is now
calculated in the background from the 'dhcpv6-options pd 0 length' node.

It is no longer mandatory to supply the 'sla-id' node, if sla-id is not
specified it is 'guessed' by counting upwards.

Example configuration:
----------------------

  ethernet eth1 {
       address dhcpv6
       dhcpv6-options {
           pd 0 {
               length 56
               interface eth2 {
                   address 1
               }
           }
       }
   }

This will request a /56 assignment from the ISP and will delegate a /64 network
to interface eth2. VyOS will use the interface address ::1 on the delegate
interface (eth2) as its local address.

2 files changed, 19 insertions, 23 deletions

diff --git a/interface-definitions/include/dhcp-options.xml.i b/interface-definitions/include/dhcp-options.xml.i
index 0f71d9321..9989291fc 100644
--- a/interface-definitions/include/dhcp-options.xml.i
+++ b/interface-definitions/include/dhcp-options.xml.i
@@ -1,6 +1,6 @@
 <node name="dhcp-options">
   <properties>
-    <help>DHCP options</help>
+    <help>DHCP client settings/options</help>
   </properties>
   <children>
     <leafNode name="client-id">
diff --git a/interface-definitions/include/dhcpv6-options.xml.i b/interface-definitions/include/dhcpv6-options.xml.i
index 98a87dba2..5d088b83d 100644
--- a/interface-definitions/include/dhcpv6-options.xml.i
+++ b/interface-definitions/include/dhcpv6-options.xml.i
@@ -1,11 +1,24 @@
 <node name="dhcpv6-options">
   <properties>
-    <help>DHCPv6 options</help>
+    <help>DHCPv6 client settings/options</help>
   </properties>
   <children>
-    <node name="prefix-delegation">
+    <leafNode name="parameters-only">
+      <properties>
+        <help>Acquire only config parameters, no address</help>
+        <valueless/>
+      </properties>
+    </leafNode>
+    <tagNode name="pd">
       <properties>
-        <help>DHCPv6 Prefix Delegation Options</help>
+        <help>DHCPv6 prefix delegation interface statement</help>
+        <valueHelp>
+          <format>instance number</format>
+          <description>Prefix delegation instance (>= 0)</description>
+        </valueHelp>
+        <constraint>
+          <validator name="numeric" argument="--non-negative"/>
+        </constraint>
       </properties>
       <children>
         <leafNode name="length">
@@ -19,6 +32,7 @@
               <validator name="numeric" argument="--range 32-64"/>
             </constraint>
           </properties>
+          <defaultValue>64</defaultValue>
         </leafNode>
         <tagNode name="interface">
           <properties>
@@ -52,28 +66,10 @@
                 </constraint>
               </properties>
             </leafNode>
-            <leafNode name="sla-len">
-              <properties>
-                <help>Site-Level aggregator (SLA) length</help>
-                <valueHelp>
-                  <format>0-128</format>
-                  <description>Length of delegated prefix</description>
-                </valueHelp>
-                <constraint>
-                  <validator name="numeric" argument="--range 0-128"/>
-                </constraint>
-              </properties>
-            </leafNode>
           </children>
         </tagNode>
       </children>
-    </node>
-    <leafNode name="parameters-only">
-      <properties>
-        <help>Acquire only config parameters, no address</help>
-        <valueless/>
-      </properties>
-    </leafNode>
+    </tagNode>
     <leafNode name="temporary">
       <properties>
         <help>IPv6 "temporary" address</help>