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.

6 files changed, 157 insertions, 59 deletions

diff --git a/data/templates/dhcp-client/ipv6.tmpl b/data/templates/dhcp-client/ipv6.tmpl
index 9673f302b..e9285d86b 100644
--- a/data/templates/dhcp-client/ipv6.tmpl
+++ b/data/templates/dhcp-client/ipv6.tmpl
@@ -8,37 +8,43 @@ interface {{ ifname }} {
     information-only;
 {% endif %}
 {% if dhcpv6_options is not defined or dhcpv6_options.temporary is not defined %}
-    send ia-na 1; # non-temporary address
+    send ia-na 0; # non-temporary address
 {% endif %}
-{% if dhcpv6_options is defined and dhcpv6_options.prefix_delegation is defined %}
-    send ia-pd 2; # prefix delegation
+{% if dhcpv6_options is defined and dhcpv6_options.pd is defined %}
+{%   for pd in dhcpv6_options.pd %}
+    send ia-pd {{ pd }}; # prefix delegation #{{ pd }}
+{%   endfor %}
 {% endif %}
 };
 
 {% if dhcpv6_options is not defined or dhcpv6_options.temporary is not defined %}
-id-assoc na 1 {
-    # Identity association NA
+id-assoc na 0 {
+    # Identity association for non temporary address
 };
 {% endif %}
 
-{% if dhcpv6_options is defined and dhcpv6_options.prefix_delegation is defined %}
-id-assoc pd 2 {
-{%   if dhcpv6_options.prefix_delegation.length is defined %}
-    prefix ::/{{ dhcpv6_options.prefix_delegation.length }} infinity;
-{%   endif %}
-{%   for interface in dhcpv6_options.prefix_delegation.interface %}
+{% if dhcpv6_options is defined and dhcpv6_options.pd is defined %}
+{%   for pd in dhcpv6_options.pd %}
+id-assoc pd {{ pd }} {
+{#   length got a default value #}
+    prefix ::/{{ dhcpv6_options.pd[pd].length }} infinity;
+{%     set sla_len = 64 - dhcpv6_options.pd[pd].length|int %}
+{%     set count = namespace(value=0) %}
+{%     for interface in dhcpv6_options.pd[pd].interface if dhcpv6_options.pd[pd].interface is defined %}
     prefix-interface {{ interface }} {
-{%     if dhcpv6_options.prefix_delegation.interface[interface].sla_id is defined %}
-        sla-id {{ dhcpv6_options.prefix_delegation.interface[interface].sla_id }};
-{%     endif %}
-{%     if dhcpv6_options.prefix_delegation.interface[interface].sla_len is defined %}
-        sla-len {{ dhcpv6_options.prefix_delegation.interface[interface].sla_len }};
-{%     endif %}
-{%     if dhcpv6_options.prefix_delegation.interface[interface].address is defined %}
-        ifid {{ dhcpv6_options.prefix_delegation.interface[interface].address }};
-{%     endif %}
+        sla-len {{ sla_len }};
+{%       if dhcpv6_options.pd[pd].interface[interface].sla_id is defined and dhcpv6_options.pd[pd].interface[interface].sla_id is not none %}
+        sla-id {{ dhcpv6_options.pd[pd].interface[interface].sla_id }};
+{%       else %}
+        sla-id {{ count.value }};
+{%       endif %}
+{%       if dhcpv6_options.pd[pd].interface[interface].address is defined and dhcpv6_options.pd[pd].interface[interface].address is not none %}
+        ifid {{ dhcpv6_options.pd[pd].interface[interface].address }};
+{%       endif %}
     };
-{%   endfor %}
+{%      set count.value = count.value + 1 %}
+{%     endfor %}
 };
+{%   endfor %}
 {% endif %}
 
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>
diff --git a/python/vyos/configdict.py b/python/vyos/configdict.py
index 010eda45c..c1e93955e 100644
--- a/python/vyos/configdict.py
+++ b/python/vyos/configdict.py
@@ -93,7 +93,7 @@ def dict_merge(source, destination):
     tmp = deepcopy(destination)
 
     for key, value in source.items():
-        if key not in tmp.keys():
+        if key not in tmp:
             tmp[key] = value
         elif isinstance(source[key], dict):
             tmp[key] = dict_merge(source[key], tmp[key])
@@ -109,15 +109,15 @@ def T2665_default_dict_cleanup(dict):
     """ Cleanup default keys for tag nodes https://phabricator.vyos.net/T2665. """
     # Cleanup
     for vif in ['vif', 'vif_s']:
-        if vif in dict.keys():
-            for key in ['ip', 'mtu']:
-                if key in dict[vif].keys():
+        if vif in dict:
+            for key in ['ip', 'mtu', 'dhcpv6_options']:
+                if key in dict[vif]:
                     del dict[vif][key]
 
             # cleanup VIF-S defaults
-            if 'vif_c' in dict[vif].keys():
-                for key in ['ip', 'mtu']:
-                    if key in dict[vif]['vif_c'].keys():
+            if 'vif_c' in dict[vif]:
+                for key in ['ip', 'mtu', 'dhcpv6_options']:
+                    if key in dict[vif]['vif_c']:
                         del dict[vif]['vif_c'][key]
                 # If there is no vif-c defined and we just cleaned the default
                 # keys - we can clean the entire vif-c dict as it's useless
@@ -129,6 +129,21 @@ def T2665_default_dict_cleanup(dict):
             if not dict[vif]:
                 del dict[vif]
 
+    if 'dhcpv6_options' in dict and 'pd' in dict['dhcpv6_options']:
+        if 'length' in dict['dhcpv6_options']['pd']:
+            del dict['dhcpv6_options']['pd']['length']
+
+    # delete empty dicts
+    if 'dhcpv6_options' in dict:
+        if 'pd' in dict['dhcpv6_options']:
+            # test if 'pd' is an empty node so we can remove it
+            if not dict['dhcpv6_options']['pd']:
+                del dict['dhcpv6_options']['pd']
+
+        # test if 'dhcpv6_options' is an empty node so we can remove it
+        if not dict['dhcpv6_options']:
+            del dict['dhcpv6_options']
+
     return dict
 
 def leaf_node_changed(conf, path):
@@ -193,6 +208,16 @@ def get_removed_vlans(conf, dict):
 
     return dict
 
+
+def dict_add_dhcpv6pd_defaults(defaults, config_dict):
+    # Implant default dictionary for DHCPv6-PD instances
+    if 'dhcpv6_options' in config_dict and 'pd' in config_dict['dhcpv6_options']:
+        for pd, pd_config in config_dict['dhcpv6_options']['pd'].items():
+            config_dict['dhcpv6_options']['pd'][pd] = dict_merge(
+                defaults, pd_config)
+
+    return config_dict
+
 def get_interface_dict(config, base, ifname=''):
     """
     Common utility function to retrieve and mandgle the interfaces available
@@ -257,15 +282,30 @@ def get_interface_dict(config, base, ifname=''):
     # remove wrongly inserted values
     dict = T2665_default_dict_cleanup(dict)
 
-    # The values are identical for vif, vif-s and vif-c as the all include the same
-    # XML definitions which hold the defaults
+    # Implant default dictionary for DHCPv6-PD instances
+    default_pd_values = defaults(base + ['dhcpv6-options', 'pd'])
+    dict = dict_add_dhcpv6pd_defaults(default_pd_values, dict)
+
+    # Implant default dictionary in vif/vif-s VLAN interfaces. Values are
+    # identical for all types of VLAN interfaces as they all include the same
+    # XML definitions which hold the defaults.
     default_vif_values = defaults(base + ['vif'])
     for vif, vif_config in dict.get('vif', {}).items():
-        vif_config = dict_merge(default_vif_values, vif_config)
+        dict['vif'][vif] = dict_add_dhcpv6pd_defaults(
+                default_pd_values, vif_config)
+        dict['vif'][vif] = T2665_default_dict_cleanup(
+                dict_merge(default_vif_values, vif_config))
+
     for vif_s, vif_s_config in dict.get('vif_s', {}).items():
-        vif_s_config = dict_merge(default_vif_values, vif_s_config)
+        dict['vif_s'][vif_s] = dict_add_dhcpv6pd_defaults(
+                default_pd_values, vif_s_config)
+        dict['vif_s'][vif_s] = T2665_default_dict_cleanup(
+                dict_merge(default_vif_values, vif_s_config))
         for vif_c, vif_c_config in vif_s_config.get('vif_c', {}).items():
-            vif_c_config = dict_merge(default_vif_values, vif_c_config)
+            dict['vif_s'][vif_s]['vif_c'][vif_c] = dict_add_dhcpv6pd_defaults(
+                    default_pd_values, vif_c_config)
+            dict['vif_s'][vif_s]['vif_c'][vif_c] = T2665_default_dict_cleanup(
+                    dict_merge(default_vif_values, vif_c_config))
 
     # Check vif, vif-s/vif-c VLAN interfaces for removal
     dict = get_removed_vlans(config, dict)
diff --git a/src/conf_mode/interfaces-pppoe.py b/src/conf_mode/interfaces-pppoe.py
index 928113b49..901ea769c 100755
--- a/src/conf_mode/interfaces-pppoe.py
+++ b/src/conf_mode/interfaces-pppoe.py
@@ -15,7 +15,6 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
-import jmespath
 
 from sys import exit
 from copy import deepcopy
@@ -104,8 +103,7 @@ def generate(pppoe):
     render(script_pppoe_ipv6_up, 'pppoe/ipv6-up.script.tmpl',
            pppoe, trim_blocks=True, permission=0o755)
 
-    tmp = jmespath.search('dhcpv6_options.prefix_delegation.interface', pppoe)
-    if tmp and len(tmp) > 0:
+    if 'dhcpv6_options' in pppoe and 'pd' in pppoe['dhcpv6_options']:
         # ipv6.tmpl relies on ifname - this should be made consitent in the
         # future better then double key-ing the same value
         render(config_wide_dhcp6c, 'dhcp-client/ipv6.tmpl', pppoe, trim_blocks=True)
diff --git a/src/migration-scripts/interfaces/11-to-12 b/src/migration-scripts/interfaces/11-to-12
new file mode 100755
index 000000000..0dad24642
--- /dev/null
+++ b/src/migration-scripts/interfaces/11-to-12
@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2020 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/>.
+
+# - rename 'dhcpv6-options prefix-delegation' from single node to a new tag node
+#   'dhcpv6-options pd 0'
+# - delete 'sla-len' from CLI - value is calculated on demand
+
+from sys import exit, argv
+from vyos.configtree import ConfigTree
+
+if __name__ == '__main__':
+    if (len(argv) < 1):
+        print("Must specify file name!")
+        exit(1)
+
+    file_name = argv[1]
+    with open(file_name, 'r') as f:
+        config_file = f.read()
+
+    config = ConfigTree(config_file)
+
+    for type in config.list_nodes(['interfaces']):
+        for interface in config.list_nodes(['interfaces', type]):
+            # cache current config tree
+            base_path = ['interfaces', type, interface, 'dhcpv6-options']
+            old_base = base_path + ['prefix-delegation']
+            new_base = base_path + ['pd']
+            if config.exists(old_base):
+                config.set(new_base)
+                config.set_tag(new_base)
+                config.copy(old_base, new_base + ['0'])
+                config.delete(old_base)
+
+                for pd in config.list_nodes(new_base):
+                    for tmp in config.list_nodes(new_base + [pd, 'interface']):
+                        sla_config = new_base + [pd, 'interface', tmp, 'sla-len']
+                        if config.exists(sla_config):
+                            config.delete(sla_config)
+
+    try:
+        with open(file_name, 'w') as f:
+            f.write(config.to_string())
+    except OSError as e:
+        print("Failed to save the modified config: {}".format(e))
+        exit(1)