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.

2 files changed, 68 insertions, 70 deletions

diff --git a/python/vyos/configdict.py b/python/vyos/configdict.py
index df4c80f23..399ac6feb 100644
--- a/python/vyos/configdict.py
+++ b/python/vyos/configdict.py
@@ -331,49 +331,83 @@ def is_source_interface(conf, interface, intftype=None):
 def get_dhcp_interfaces(conf, vrf=None):
     """ Common helper functions to retrieve all interfaces from current CLI
     sessions that have DHCP configured. """
+    # Cache and reset config level
+    old_level = conf.get_level()
+    conf.set_level([])
+
     dhcp_interfaces = {}
     dict = conf.get_config_dict(['interfaces'], get_first_key=True)
     if not dict:
         return dhcp_interfaces
 
-    def check_dhcp(config, ifname):
+    def check_dhcp(config):
+        ifname = config['ifname']
         tmp = {}
-        if dict_search('address', config) == 'dhcp' or dict_search('default_route', config) != None:
+        if 'address' in config and 'dhcp' in config['address']:
             options = {}
             if dict_search('dhcp_options.default_route_distance', config) != None:
-                options.update({'distance' : config['dhcp_options']['default_route_distance']})
-            if dict_search('default_route', config) != None:
-                options.update({'distance' : config['default_route']})
+                options.update({'dhcp_options' : config['dhcp_options']})
             if 'vrf' in config:
                 if vrf is config['vrf']: tmp.update({ifname : options})
             else: tmp.update({ifname : options})
+
         return tmp
 
     for section, interface in dict.items():
         for ifname in interface:
-            # always reset config level
+            # always reset config level, as get_interface_dict() will alter it
             conf.set_level([])
             # we already have a dict representation of the config from get_config_dict(),
             # but with the extended information from get_interface_dict() we also
             # get the DHCP client default-route-distance default option if not specified.
             ifconfig = get_interface_dict(conf, ['interfaces', section], ifname)
 
-            tmp = check_dhcp(ifconfig, ifname)
+            tmp = check_dhcp(ifconfig)
             dhcp_interfaces.update(tmp)
             # check per VLAN interfaces
             for vif, vif_config in ifconfig.get('vif', {}).items():
-                tmp = check_dhcp(vif_config, f'{ifname}.{vif}')
+                tmp = check_dhcp(vif_config)
                 dhcp_interfaces.update(tmp)
             # check QinQ VLAN interfaces
-            for vif_s, vif_s_config in ifconfig.get('vif-s', {}).items():
-                tmp = check_dhcp(vif_s_config, f'{ifname}.{vif_s}')
+            for vif_s, vif_s_config in ifconfig.get('vif_s', {}).items():
+                tmp = check_dhcp(vif_s_config)
                 dhcp_interfaces.update(tmp)
-                for vif_c, vif_c_config in vif_s_config.get('vif-c', {}).items():
-                    tmp = check_dhcp(vif_c_config, f'{ifname}.{vif_s}.{vif_c}')
+                for vif_c, vif_c_config in vif_s_config.get('vif_c', {}).items():
+                    tmp = check_dhcp(vif_c_config)
                     dhcp_interfaces.update(tmp)
 
+    # reset old config level
     return dhcp_interfaces
 
+def get_pppoe_interfaces(conf, vrf=None):
+    """ Common helper functions to retrieve all interfaces from current CLI
+    sessions that have DHCP configured. """
+    # Cache and reset config level
+    old_level = conf.get_level()
+    conf.set_level([])
+
+    pppoe_interfaces = {}
+    for ifname in conf.list_nodes(['interfaces', 'pppoe']):
+        # always reset config level, as get_interface_dict() will alter it
+        conf.set_level([])
+        # we already have a dict representation of the config from get_config_dict(),
+        # but with the extended information from get_interface_dict() we also
+        # get the DHCP client default-route-distance default option if not specified.
+        ifconfig = get_interface_dict(conf, ['interfaces', 'pppoe'], ifname)
+
+        options = {}
+        if 'default_route_distance' in ifconfig:
+            options.update({'default_route_distance' : ifconfig['default_route_distance']})
+        if 'no_default_route' in ifconfig:
+            options.update({'no_default_route' : {}})
+        if 'vrf' in ifconfig:
+            if vrf is ifconfig['vrf']: pppoe_interfaces.update({ifname : options})
+        else: pppoe_interfaces.update({ifname : options})
+
+    # reset old config level
+    conf.set_level(old_level)
+    return pppoe_interfaces
+
 def get_interface_dict(config, base, ifname=''):
     """
     Common utility function to retrieve and mangle the interfaces configuration
diff --git a/python/vyos/ifconfig/pppoe.py b/python/vyos/ifconfig/pppoe.py
index 1d13264bf..63ffc8069 100644
--- a/python/vyos/ifconfig/pppoe.py
+++ b/python/vyos/ifconfig/pppoe.py
@@ -27,12 +27,13 @@ class PPPoEIf(Interface):
         },
     }
 
-    def _remove_routes(self, vrf=''):
+    def _remove_routes(self, vrf=None):
         # Always delete default routes when interface is removed
+        vrf_cmd = ''
         if vrf:
-            vrf = f'-c "vrf {vrf}"'
-        self._cmd(f'vtysh -c "conf t" {vrf} -c "no ip route 0.0.0.0/0 {self.ifname} tag 210"')
-        self._cmd(f'vtysh -c "conf t" {vrf} -c "no ipv6 route ::/0 {self.ifname} tag 210"')
+            vrf_cmd = f'-c "vrf {vrf}"'
+        self._cmd(f'vtysh -c "conf t" {vrf_cmd} -c "no ip route 0.0.0.0/0 {self.ifname} tag 210"')
+        self._cmd(f'vtysh -c "conf t" {vrf_cmd} -c "no ipv6 route ::/0 {self.ifname} tag 210"')
 
     def remove(self):
         """
@@ -44,11 +45,11 @@ class PPPoEIf(Interface):
         >>> i = Interface('pppoe0')
         >>> i.remove()
         """
-
+        vrf = None
         tmp = get_interface_config(self.ifname)
-        vrf = ''
         if 'master' in tmp:
-            self._remove_routes(tmp['master'])
+            vrf = tmp['master']
+        self._remove_routes(vrf)
 
         # remove bond master which places members in disabled state
         super().remove()
@@ -84,10 +85,12 @@ class PPPoEIf(Interface):
         self._config = config
 
         # remove old routes from an e.g. old VRF assignment
-        vrf = ''
-        if 'vrf_old' in config:
-            vrf = config['vrf_old']
-        self._remove_routes(vrf)
+        if 'shutdown_required':
+            vrf = None
+            tmp = get_interface_config(self.ifname)
+            if 'master' in tmp:
+                vrf = tmp['master']
+            self._remove_routes(vrf)
 
         # DHCPv6 PD handling is a bit different on PPPoE interfaces, as we do
         # not require an 'address dhcpv6' CLI option as with other interfaces
@@ -98,54 +101,15 @@ class PPPoEIf(Interface):
 
         super().update(config)
 
-        if 'default_route' not in config or config['default_route'] == 'none':
-            return
-
-        #
-        # Set default routes pointing to pppoe interface
-        #
-        vrf = ''
-        sed_opt = '^ip route'
-
-        install_v4 = True
-        install_v6 = True
-
         # generate proper configuration string when VRFs are in use
+        vrf = ''
         if 'vrf' in config:
             tmp = config['vrf']
             vrf = f'-c "vrf {tmp}"'
-            sed_opt = f'vrf {tmp}'
-
-        if config['default_route'] == 'auto':
-            # only add route if there is no default route present
-            tmp = self._cmd(f'vtysh -c "show running-config staticd no-header" | sed -n "/{sed_opt}/,/!/p"')
-            for line in tmp.splitlines():
-                line = line.lstrip()
-                if line.startswith('ip route 0.0.0.0/0'):
-                    install_v4 = False
-                    continue
-
-                if 'ipv6' in config and line.startswith('ipv6 route ::/0'):
-                    install_v6 = False
-                    continue
-
-        elif config['default_route'] == 'force':
-            # Force means that all static routes are replaced with the ones from this interface
-            tmp = self._cmd(f'vtysh -c "show running-config staticd no-header" | sed -n "/{sed_opt}/,/!/p"')
-            for line in tmp.splitlines():
-                if self.ifname in line:
-                    # It makes no sense to remove a route with our interface and the later re-add it.
-                    # This will only make traffic disappear - which is a no-no!
-                    continue
-
-                line = line.lstrip()
-                if line.startswith('ip route 0.0.0.0/0'):
-                    self._cmd(f'vtysh -c "conf t" {vrf} -c "no {line}"')
-
-                if 'ipv6' in config and line.startswith('ipv6 route ::/0'):
-                    self._cmd(f'vtysh -c "conf t" {vrf} -c "no {line}"')
-
-        if install_v4:
-            self._cmd(f'vtysh -c "conf t" {vrf} -c "ip route 0.0.0.0/0 {self.ifname} tag 210"')
-        if install_v6 and 'ipv6' in config:
-            self._cmd(f'vtysh -c "conf t" {vrf} -c "ipv6 route ::/0 {self.ifname} tag 210"')
+
+        if 'no_default_route' not in config:
+            # Set default route(s) pointing to PPPoE interface
+            distance = config['default_route_distance']
+            self._cmd(f'vtysh -c "conf t" {vrf} -c "ip route 0.0.0.0/0 {self.ifname} tag 210 {distance}"')
+            if 'ipv6' in config:
+                self._cmd(f'vtysh -c "conf t" {vrf} -c "ipv6 route ::/0 {self.ifname} tag 210 {distance}"')