ddwrt-ovpn-client-watchdog.sh

#!/bin/sh
DEBUG=; set -x # uncomment/comment to enable/disable debug mode

#          name: ddwrt-ovpn-client-watchdog.sh
#       version: 2.0.2, 24-jul-2022, by eibgrad
#       purpose: (re)start failed/stopped/unresponsive openvpn client
#   script type: wanup (autostart)
#  installation:
#    1. enable jffs2 (administration->jffs2)
#    2. enable syslogd (services->services->system log)
#    3. use shell (telnet/ssh) to execute one of the following commands:
#         curl -kLs bit.ly/ddwrt-installer|tr -d '\r'|sh -s -- iNC273ER wanup
#       or
#         wget -qO - bit.ly/ddwrt-installer|tr -d '\r'|sh -s -- iNC273ER wanup
#    4. (optional): use vi editor to modify options:
#         vi /jffs/etc/config/ddwrt-ovpn-client-watchdog.wanup
#    5. reboot
(
# ------------------------------ BEGIN OPTIONS ------------------------------- #

# time (in secs) between checks for failed/stopped/unresponsive openvpn clients
INTERVAL=60

# internet host used for ping checks
PING_HOST='8.8.8.8'

# time (in secs) between ping checks
PING_INTERVAL=10

# maxmium number of ping checks before being considered a failure
PING_MAXTRY=3 # (3 recommended, 0 disables ping checks)

# ------------------------------- END OPTIONS -------------------------------- #

# ---------------------- DO NOT CHANGE BELOW THIS LINE ----------------------- #

WAN_IF="$(ip route | awk '/^default/{print $NF}')"
OVPN_CONF='/tmp/openvpncl/openvpn.conf'

# function _ping()
_ping() {
    [ $PING_MAXTRY -gt 0 ] || return 0

    local i=1
    local dev="$(grep '^dev\s' $OVPN_CONF | tail -1 | awk '{print $2}')"

    # it's best to check multiple times to prevent false negatives
    while :; do
        ping -qc1 -W3 -I $dev $PING_HOST &>/dev/null && return 0
        [ $(( i++ )) -ge $PING_MAXTRY ] && break || sleep $PING_INTERVAL
    done

    return 1
}

# reject uninitialized wan and additional instances
{ [ "$WAN_IF" ] && mkdir /tmp/$(basename $0 .wanup).lock &>/dev/null; } || exit 0

# wait for *reliable* internet connection
until ping -qc1 -W3 -I $WAN_IF $PING_HOST &>/dev/null; do sleep 10; done

while sleep $INTERVAL; do
    # openvpn client must be enabled
    [ "$(nvram get openvpncl_enable)" != '0' ] || continue

    # check for failed connection or unresponsive tunnel
    ps | grep -q [o]penvpncl && _ping && continue

    # fall-through means failure; restart the openvpn client
    openvpn --config $OVPN_CONF --daemon
    echo "openvpn client (re)started @ $(date)"
done

) 2>&1 | logger -p user.$([ ${DEBUG+x} ] && echo 'debug' || echo 'notice') \
    -t $(echo $(basename $0) | grep -Eo '^.{0,23}')[$$] &