OpenWRT router online check and re-up

router-onlinecheck.sh

#!/bin/bash
#
# This script is running on OpenWRT 18.04.3
# AArch64-Xiaomi-AX6S
#
# Requirements:
# bash 5.1.16
# curl 7.83.1 (2022-05-11)
#
# This script should be run with an interval longer than LCP request.
# Currently, the LCP request and response threshold is using a time window of 100 seconds, so this script should be run per 2 minutes.
#
# Aiming at assist for online detection, if LCP does NOT detect PPP session terminated
# after 2 retries with 5 seconds interval, this script will bring down WAN and bring it up again.
# after bring it down and up, wait for 15 seconds, if still not online and RESERVE_VOLATILE_LOG == 0, reboot the whole router
#
# Currently, the PPP session will be restarted if 20 failures of LCP request, each request has an interval of 5 seconds.
#
# Crontab: 
# */5 * * * * /bin/bash /etc/router-onlinecheck.sh

IFUP_BIN="/sbin/ifup"
IFDOWN_BIN="/sbin/ifdown"
RBT_BIN="/sbin/reboot"
WAN_IFACE="wan wan6"
RESERVE_VOLATILE_LOG=1
LOG_BIN="/usr/bin/logger"
PROGNAME="yconncheck"
CURL_BIN="/usr/bin/curl"


BARK_APIURL="https://bark.pushserver.example.com/push"
BARK_CRED="myuser:mypassword"
BARK_DEST_DEV="my-mobile-dev-push-device-id"
NET_LOC="my-home-network-location"


function ReOnlinePush(){
    ${CURL_BIN} -X "POST" "${BARK_APIURL}" \
     -H 'Content-Type: application/json; charset=utf-8' \
     -u "${BARK_CRED}" \
     -d "{\"badge\":1,\"device_key\":\"${BARK_DEST_DEV}\",\"isArchive\":\"1\",\"title\":\"Connectivity Health\",\"level\":\"timeSensitive\",\"group\":\"NetworkAvail\",\"body\": \"Network is restarted on ${NET_LOC}\"}" \
     -m 3 --connect-time 3
    ${LOG_BIN} -t "${PROGNAME}" "Send a push notification to admin via Bark."
}

CON_ONLINE=$(${CURL_BIN} --connect-time 3 -m 3 -s --retry-delay 5 --retry 2 --retry-all-errors -S -o /dev/null -w '%{http_code}' "https://connect.rom.miui.com/generate_204")

if [[ ${CON_ONLINE} -eq 204 ]]; then
    ${LOG_BIN} -t "${PROGNAME}" "Network connection is online."
    exit 0
else
    ${LOG_BIN} -t "${PROGNAME}" "Connection Offline."
    ${IFDOWN_BIN} ${WAN_IFACE}
    sleep 5
    ${IFUP_BIN} ${WAN_IFACE}
    sleep 15
    AGN_CON_ONLINE=$(${CURL_BIN} --connect-time 3 -m 3 -s --retry-delay 5 --retry 2 --retry-all-errors -S -o /dev/null -w '%{http_code}' "https://connect.rom.miui.com/generate_204")
    if [[ ${AGN_CON_ONLINE} -eq 204 ]]; then
        ${LOG_BIN} -t "${PROGNAME}" "Connection online after bring down and up."
        ReOnlinePush
        exit 0
    else
        ${LOG_BIN} -t "${PROGNAME}" "Connection cannot be automatically recovered from disaster."
        if [[ ${RESERVE_VOLATILE_LOG} -eq 0 ]]; then
            ${LOG_BIN} -t "${PROGNAME}" "Configured to reboot after 15s."
            sleep 15
            ${RBT_BIN}
            exit 0
        fi
        exit 0
    fi
fi