From c5d95d0e5e62958097d7f3953fc0f1376c0f7995 Mon Sep 17 00:00:00 2001
From: f <f@sutty.nl>
Date: Mon, 26 Sep 2022 16:01:02 -0300
Subject: [PATCH] Static routing.

OVH network assigns IP addresses on a /32 subnet, so we can't add a
default gateway because it's outside the subnet.
---
 config.yml                                  |  2 +
 tasks/post_install.yml                      |  6 ++
 tasks/update.yml                            |  6 ++
 templates/etc/network/interfaces.j2         |  2 +-
 templates/usr/libexec/ifupdown-ng/routes.j2 | 72 +++++++++++++++++++++
 5 files changed, 87 insertions(+), 1 deletion(-)
 create mode 100755 templates/usr/libexec/ifupdown-ng/routes.j2

diff --git a/config.yml b/config.yml
index 8c56691..d317b2d 100644
--- a/config.yml
+++ b/config.yml
@@ -40,6 +40,8 @@ templates:
 - "/etc/sysctl.d/coredump.conf"
 - "/etc/docker/daemon.json"
 - "/etc/ntp.conf"
+executables:
+- "/usr/libexec/ifupdown-ng/routes"
 services:
 - runlevel: "sysinit"
   service: "devfs"
diff --git a/tasks/post_install.yml b/tasks/post_install.yml
index cb81646..74f1d44 100644
--- a/tasks/post_install.yml
+++ b/tasks/post_install.yml
@@ -9,6 +9,12 @@
     dest: "/mnt{{ item }}"
     mode: "640"
   loop: "{{ templates }}"
+- name: "Also executables."
+  template:
+    src: "templates{{ item }}.j2"
+    dest: "/mnt{{ item }}"
+    mode: "750"
+  loop: "{{ executables }}"
 - name: "And services."
   template:
     src: "templates{{ item }}.j2"
diff --git a/tasks/update.yml b/tasks/update.yml
index b5f871e..d8ca695 100644
--- a/tasks/update.yml
+++ b/tasks/update.yml
@@ -7,6 +7,12 @@
     dest: "{{ item }}"
     mode: "640"
   loop: "{{ templates }}"
+- name: "Also executables."
+  template:
+    src: "templates{{ item }}.j2"
+    dest: "{{ item }}"
+    mode: "750"
+  loop: "{{ executables }}"
 - name: "And services."
   template:
     src: "templates{{ item }}.j2"
diff --git a/templates/etc/network/interfaces.j2 b/templates/etc/network/interfaces.j2
index 3dc60ce..e142da6 100644
--- a/templates/etc/network/interfaces.j2
+++ b/templates/etc/network/interfaces.j2
@@ -6,7 +6,7 @@ auto eth0
 
 iface eth0 inet static
   address {{ ansible_host }}/{{ netmask }}
-  gateway {{ gateway }}
+  routes-static {{ gateway }},default via {{ gateway }}
 
 {% if ip6 is defined %}
 iface eth0 inet6 static
diff --git a/templates/usr/libexec/ifupdown-ng/routes.j2 b/templates/usr/libexec/ifupdown-ng/routes.j2
new file mode 100755
index 0000000..9b37e3d
--- /dev/null
+++ b/templates/usr/libexec/ifupdown-ng/routes.j2
@@ -0,0 +1,72 @@
+#!/bin/sh
+# https://github.com/ifupdown-ng/ifupdown-ng/issues/42#issuecomment-849135927
+[ -z "${VERBOSE}" ] || set -x
+
+# routes-static 1.2.3.0/24,10.0.0.0/8 via 1.2.3.4
+# routes-rule dport 25 table 123,dport 587 table 123
+
+# adds $3 to $1 if $1 does not contain $2
+addif() {
+	if [ "$1" = "${1%$2*}" ]; then
+		echo $1 $3
+	else
+		echo $1
+	fi
+}
+decidr() {
+	echo "${1%/*}"
+}
+addsrc() {
+	addif "$1" src "src $(decidr $IF_ADDRESS)"
+}
+adddev() {
+	addif "$1" dev "dev $IFACE"
+}
+
+# $1: input string
+# $2: delimeter
+# $3: function to call
+foreach() {
+	list="$1"
+
+	while [ -n "$list" ]; do
+		line="${list%%$2*}"
+		list="${list#*$2}"
+		"$3" "$line"
+
+		[ "$line" = "$list" ] && break
+	done
+}
+
+# add a route
+prep() {
+	route="$1"
+	route=$(addsrc "$route")
+	route=$(adddev "$route")
+	echo $route
+}
+routeadd() {
+	${MOCK} ip route add $(prep "$1")
+}
+routedel() {
+	${MOCK} ip route del $(prep "$1")
+}
+
+ruleadd() {
+	${MOCK} ip rule add $1
+}
+ruledel() {
+	${MOCK} ip rule del $1
+}
+
+case "$PHASE" in
+up)
+	foreach "$IF_ROUTES_STATIC" , routeadd
+	foreach "$IF_ROUTES_RULE" , ruleadd
+	;;
+down)
+	foreach "$IF_ROUTES_STATIC" , routedel
+	foreach "$IF_ROUTES_RULE" , ruledel
+	;;
+*) exit 0 ;;
+esac