merlin-ovpn-sync-routes.sh

#!/bin/sh
#DEBUG= # uncomment/comment to enable/disable debug mode

#          name: merlin-ovpn-sync-routes.sh
#       version: 2.0.0, 22-jul-2022, by eibgrad
#       purpose: synchronize openvpn client and server routing tables
#       type(s): openvpn-event
#          href: https://tinyurl.com/2jenwbe5
#  installation:
#    1. enable jffs custom scripts and configs (administration->system)
#    2. ssh to router and copy/paste the following command:
#         curl -kLs bit.ly/merlin-installer|tr -d '\r'|sh -s kTThBV46
#    3. reboot

SCRIPTS_DIR='/jffs/scripts'
SCRIPT1="$SCRIPTS_DIR/merlin-ovpn-sync-routes.sh"
SCRIPT2="$SCRIPTS_DIR/openvpn-event"

mkdir -p $SCRIPTS_DIR

# ---------------------- begin merlin-ovpn-sync-routes ----------------------- #
cat << 'EOF' > $SCRIPT1
#!/bin/sh
#set -x # comment/uncomment to disable/enable debug mode
{
# required for serialization when reentry is possible
LOCK="/tmp/var/lock/$(basename $0).lock"
acquire_lock() { while ! mkdir $LOCK &>/dev/null; do sleep 2; done; }
release_lock() { rmdir $LOCK &>/dev/null; }

# exit (any concurrent instance(s) may now run)
exit_0() { release_lock; exit 0; }

# one instance at a time
acquire_lock

# only relevant for routed (tun) openvpn server up event
[[ "${dev:0:4}" == 'tun2' && "$script_type" == 'up' ]] || exit_0

# ensure every openvpn client's routing policy table ...
for i in 1 2 3 4 5; do
    [ "$(ip route show table ovpnc${i})" ] || continue

    # ... contains the server's ip network on the tunnel
    while read route; do
        ip route add $route table ovpnc${i} 2>/dev/null && routing_changed=
    done << EOR
    $(ip route | grep $dev)
EOR
done

# force routing system to recognize any changes
[ ${routing_changed+x} ] && ip route flush cache

exit_0
} 2>&1 | logger -t $(basename $0 .sh)[$$]
EOF
[ ${DEBUG+x} ] && sed -ri '2 s/^#(set -x)/\1/' $SCRIPT1
chmod +x $SCRIPT1
echo "installed: $SCRIPT1"
# ----------------------- end merlin-ovpn-sync-routes ------------------------ #

# --------------------------- begin openvpn-event ---------------------------- #
create_script() {
cat << 'EOF' > $SCRIPT2
#!/bin/sh
#set -x # comment/uncomment to disable/enable debug mode
{
$SCRIPT1
} 2>&1 | logger -t $(basename $0)[$$]
EOF
[ ${DEBUG+x} ] && sed -ri '2 s/^#(set -x)/\1/' $SCRIPT2
sed "s:\$SCRIPT1:$SCRIPT1:g" -i $SCRIPT2
chmod +x $SCRIPT2
}

if [ -f $SCRIPT2 ]; then
    echo "error: $SCRIPT2 already exists; requires manual installation"
else
    create_script
    echo "installed: $SCRIPT2"
fi
# ---------------------------- end openvpn-event ----------------------------- #