pppoe: T4384: replace default-route CLI option with common CLI nodes already present for DHCP

VyOS 1.4 still leverages PPPd internals on the CLI.

pppd supports three options for a default route, none, auto, force.
* none: No default route is installed on interface up
* auto: Default route is only installed if there is yet no default route
* force: overwrite any default route

There are several drawbacks in this design for VyOS and the users. If auto is
specified, this only counted for static default routes - but what about dynamic
ones? Same for force, only a static default route got replaced but dynamic ones
did not got taken into account.

The CLI is changed and we now re-use already existing nodes from the DHCP
interface configuration:
* no-default-route:
  On link up no default route is installed, same as the previous
  default-route none

* default-route-distance:
  We can now specify the distance of this route for the routing table on the
  system. This defaults to 210 as we have for DHCP interfaces. All this will be
  migrated using a CLI migration script.

1 files changed, 12 insertions, 23 deletions

diff --git a/src/conf_mode/interfaces-pppoe.py b/src/conf_mode/interfaces-pppoe.py
index bfb1fadd5..279369a32 100755
--- a/src/conf_mode/interfaces-pppoe.py
+++ b/src/conf_mode/interfaces-pppoe.py
@@ -22,7 +22,9 @@ from netifaces import interfaces
 
 from vyos.config import Config
 from vyos.configdict import get_interface_dict
+from vyos.configdict import is_node_changed
 from vyos.configdict import leaf_node_changed
+from vyos.configdict import get_pppoe_interfaces
 from vyos.configverify import verify_authentication
 from vyos.configverify import verify_source_interface
 from vyos.configverify import verify_interface_exists
@@ -52,28 +54,12 @@ def get_config(config=None):
     # We should only terminate the PPPoE session if critical parameters change.
     # All parameters that can be changed on-the-fly (like interface description)
     # should not lead to a reconnect!
-    tmp = leaf_node_changed(conf, ['access-concentrator'])
-    if tmp: pppoe.update({'shutdown_required': {}})
-
-    tmp = leaf_node_changed(conf, ['connect-on-demand'])
-    if tmp: pppoe.update({'shutdown_required': {}})
-
-    tmp = leaf_node_changed(conf, ['service-name'])
-    if tmp: pppoe.update({'shutdown_required': {}})
-
-    tmp = leaf_node_changed(conf, ['source-interface'])
-    if tmp: pppoe.update({'shutdown_required': {}})
-
-    tmp = leaf_node_changed(conf, ['vrf'])
-    # leaf_node_changed() returns a list, as VRF is a non-multi node, there
-    # will be only one list element
-    if tmp: pppoe.update({'vrf_old': tmp[0]})
-
-    tmp = leaf_node_changed(conf, ['authentication', 'user'])
-    if tmp: pppoe.update({'shutdown_required': {}})
-
-    tmp = leaf_node_changed(conf, ['authentication', 'password'])
-    if tmp: pppoe.update({'shutdown_required': {}})
+    for options in ['access-concentrator', 'connect-on-demand', 'service-name',
+                    'source-interface', 'vrf', 'no-default-route', 'authentication']:
+        if is_node_changed(conf, options):
+            pppoe.update({'shutdown_required': {}})
+            # bail out early - no need to further process other nodes
+            break
 
     return pppoe
 
@@ -120,7 +106,7 @@ def apply(pppoe):
         return None
 
     # reconnect should only be necessary when certain config options change,
-    # like ACS name, authentication, no-peer-dns, source-interface
+    # like ACS name, authentication ... (see get_config() for details)
     if ((not is_systemd_service_running(f'ppp@{ifname}.service')) or
         'shutdown_required' in pppoe):
 
@@ -130,6 +116,9 @@ def apply(pppoe):
             p.remove()
 
         call(f'systemctl restart ppp@{ifname}.service')
+        # When interface comes "live" a hook is called:
+        # /etc/ppp/ip-up.d/99-vyos-pppoe-callback
+        # which triggers PPPoEIf.update()
     else:
         if os.path.isdir(f'/sys/class/net/{ifname}'):
             p = PPPoEIf(ifname)