From 927c98f23a6317e2e3565032023d68b753d71037 Mon Sep 17 00:00:00 2001
From: Christian Poessinger <christian@poessinger.com>
Date: Fri, 10 Apr 2020 13:28:46 +0200
Subject: pppoe: T2248: connect-on-demand and vrf are mutually exclusive

As PPP can be used to establish a connection on-demand it manages the Kernel
default route. This can not be used when using VRFs which are managed by
the ip-up.d and ip-down.d scripts - thus those options are now mutially
exclusive.

The best fix would be adding support for VRFs into PPP.
---
 data/templates/pppoe/ip-down.script.tmpl |  6 ++++--
 data/templates/pppoe/ip-up.script.tmpl   | 12 ++++++------
 data/templates/pppoe/peer.tmpl           |  9 +++++++++
 src/conf_mode/interfaces-pppoe.py        |  3 +++
 4 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/data/templates/pppoe/ip-down.script.tmpl b/data/templates/pppoe/ip-down.script.tmpl
index e76875f12..a68fc099c 100644
--- a/data/templates/pppoe/ip-down.script.tmpl
+++ b/data/templates/pppoe/ip-down.script.tmpl
@@ -10,8 +10,9 @@ fi
 DIALER_PID=$(cat /var/run/{{ intf }}.pid)
 logger -t pppd[$DIALER_PID] "executing $0"
 
-# Determine if we are enslaved to a VRF, this is needed to properly insert
-# the default route
+{% if not on_demand %}
+# See https://phabricator.vyos.net/T2248. Determine if we are enslaved to a
+# VRF, this is needed to properly insert the default route.
 VRF_NAME=""
 if [ -d /sys/class/net/{{ intf }}/upper_* ]; then
     # Determine upper (VRF) interface
@@ -24,3 +25,4 @@ fi
 
 # Always delete default route when interface goes down
 vtysh -c "conf t" ${VRF_NAME} -c "no ip route 0.0.0.0/0 {{ intf }} ${VRF_NAME}"
+{% endif %}
diff --git a/data/templates/pppoe/ip-up.script.tmpl b/data/templates/pppoe/ip-up.script.tmpl
index 4cc779914..697ebcc20 100644
--- a/data/templates/pppoe/ip-up.script.tmpl
+++ b/data/templates/pppoe/ip-up.script.tmpl
@@ -6,13 +6,15 @@ if [ "$6" != "{{ intf }}" ]; then
     exit
 fi
 
-set -x
+{% if not on_demand %}
+# See https://phabricator.vyos.net/T2248 & T2220. Determine if we are enslaved
+# to a VRF, this is needed to properly insert the default route.
 
 # add some info to syslog
 DIALER_PID=$(cat /var/run/{{ intf }}.pid)
 logger -t pppd[$DIALER_PID] "executing $0"
 
-SED_OPT="ip route"
+SED_OPT="^ip route"
 VRF_NAME=""
 if [ -d /sys/class/net/{{ intf }}/upper_* ]; then
     # Determine upper (VRF) interface
@@ -25,10 +27,8 @@ if [ -d /sys/class/net/{{ intf }}/upper_* ]; then
     VRF_NAME="vrf ${VRF}"
 fi
 
-# Debian PPP version has no support for replacing an existing default route
-# thus we emulate this ba an ip-up script https://phabricator.vyos.net/T2220.
 {% if 'auto' in default_route -%}
-# only insert a new default route if there is no default route configured
+# Only insert a new default route if there is no default route configured
 routes=$(vtysh -c "show running-config" | sed -n "/${SED_OPT}/,/!/p" | grep 0.0.0.0/0 | wc -l)
 if [ "$routes" -ne 0 ]; then
     exit 1
@@ -44,4 +44,4 @@ done
 # Add default route to default or VRF routing table
 vtysh -c "conf t" ${VTY_OPT} -c "ip route 0.0.0.0/0 {{ intf }} ${VRF_NAME}"
 logger -t pppd[$DIALER_PID] "added default route via {{ intf }} ${VRF_NAME}"
-
+{% endif %}
diff --git a/data/templates/pppoe/peer.tmpl b/data/templates/pppoe/peer.tmpl
index 8651f12a5..36d108cee 100644
--- a/data/templates/pppoe/peer.tmpl
+++ b/data/templates/pppoe/peer.tmpl
@@ -60,4 +60,13 @@ rp_pppoe_service "{{ service_name }}"
 {% endif %}
 {% if on_demand %}
 demand
+# See T2249. PPP default route options should only be set when in on-demand
+# mode. As soon as we are not in on-demand mode the default-route handling is
+# passed to the ip-up.d/ip-down.s scripts which is required for VRF support.
+{% if 'auto' in default_route -%}
+defaultroute
+{% elif 'force' in default_route -%}
+defaultroute
+replacedefaultroute
+{% endif %}
 {% endif %}
diff --git a/src/conf_mode/interfaces-pppoe.py b/src/conf_mode/interfaces-pppoe.py
index 5f073dac6..353a5a12c 100755
--- a/src/conf_mode/interfaces-pppoe.py
+++ b/src/conf_mode/interfaces-pppoe.py
@@ -155,6 +155,9 @@ def verify(pppoe):
     if vrf_name and vrf_name not in interfaces():
         raise ConfigError(f'VRF {vrf_name} does not exist')
 
+    if pppoe['on_demand'] and pppoe['vrf']:
+        raise ConfigError('On-demand dialing and VRF can not be used at the same time')
+
     return None
 
 def generate(pppoe):
-- 
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