# NOTE: here we use 'ip' wrapper, therefore a route will be actually deleted via /usr/sbin/ip or vtysh, according to the system state

if [[ $reason =~ (EXPIRE|FAIL|RELEASE|STOP) ]]; then
    # delete dynamic nameservers from a configuration if lease was deleted
    logmsg info "Deleting nameservers with tag \"dhcp-${interface}\" via vyos-hostsd-client"
    vyos-hostsd-client --delete-name-servers --tag dhcp-${interface}
    # try to delete default ip route 
    for router in $old_routers; do
        logmsg info "Deleting default route: via $router dev ${interface}"
        ip -4 route del default via $router dev ${interface}
    done
    # delete rfc3442 routes
    if [ -n "$old_rfc3442_classless_static_routes" ]; then
        set -- $old_rfc3442_classless_static_routes
        while [ $# -gt 0 ]; do
            net_length=$1
            via_arg=''
            case $net_length in
                32|31|30|29|28|27|26|25)
                    if [ $# -lt 9 ]; then
                        return 1
                    fi
                    net_address="${2}.${3}.${4}.${5}"
                    gateway="${6}.${7}.${8}.${9}"
                    shift 9
                    ;;
                24|23|22|21|20|19|18|17)
                    if [ $# -lt 8 ]; then
                        return 1
                    fi
                    net_address="${2}.${3}.${4}.0"
                    gateway="${5}.${6}.${7}.${8}"
                    shift 8
                    ;;
                16|15|14|13|12|11|10|9)
                    if [ $# -lt 7 ]; then
                        return 1
                    fi
                    net_address="${2}.${3}.0.0"
                    gateway="${4}.${5}.${6}.${7}"
                    shift 7
                    ;;
                8|7|6|5|4|3|2|1)
                    if [ $# -lt 6 ]; then
                        return 1
                    fi
                    net_address="${2}.0.0.0"
                    gateway="${3}.${4}.${5}.${6}"
                    shift 6
                    ;;
                0)  # default route
                    if [ $# -lt 5 ]; then
                        return 1
                    fi
                    net_address="0.0.0.0"
                    gateway="${2}.${3}.${4}.${5}"
                    shift 5
                    ;;
                *)  # error
                    return 1
                    ;;
            esac
            # take care of link-local routes
            if [ "${gateway}" != '0.0.0.0' ]; then
                via_arg="via ${gateway}"
            fi
            # delete route (ip detects host routes automatically)
            ip -4 route del "${net_address}/${net_length}" \
                ${via_arg} dev "${interface}" >/dev/null 2>&1
        done
    fi
fi

if [[ $reason =~ (EXPIRE6|RELEASE6|STOP6) ]]; then
    # delete dynamic nameservers from a configuration if lease was deleted
    logmsg info "Deleting nameservers with tag \"dhcpv6-${interface}\" via vyos-hostsd-client"
    vyos-hostsd-client --delete-name-servers --tag dhcpv6-${interface}
fi