#!/bin/bash

#

# dhclient-script: Network interface configuration script run by

#                  dhclient based on DHCP client communication

#

# Copyright (C) 2008-2014  Red Hat, Inc.

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program.  If not, see <http://www.gnu.org/licenses/>.

#

# Author(s): David Cantrell <dcantrell@redhat.com>

#            Jiri Popelka <jpopelka@redhat.com>

#

# ----------

# This script is a rewrite/reworking on dhclient-script originally

# included as part of dhcp-970306:

# dhclient-script for Linux. Dan Halbert, March, 1997.

# Updated for Linux 2.[12] by Brian J. Murrell, January 1999.

# Modified by David Cantrell <dcantrell@redhat.com> for Fedora and RHEL

# ----------

#

PATH=/bin:/usr/bin:/sbin

# scripts in dhclient.d/ use $SAVEDIR (#833054)

SAVEDIR=/var/lib/dhclient

LOGFACILITY="local7"

LOGLEVEL="notice"

ETCDIR="/etc/dhcp"

logmessage() {

    msg="${1}"

    logger -p ${LOGFACILITY}.${LOGLEVEL} -t "NET" "dhclient: ${msg}"

}

if [ -x /sbin/restorecon ]; then

    fix_context() {

        /sbin/restorecon ${1} >/dev/null 2>&1

    }

else

    fix_context() { :; }

fi

eventually_add_hostnames_domain_to_search() {

# For the case when hostname for this machine has a domain that is not in domain_search list

# 1) get a hostname with `ipcalc --hostname` or `hostname`

# 2) get the domain from this hostname

# 3) add this domain to search line in resolv.conf if it's not already

#    there (domain list that we have recently added there is a parameter of this function)

# We can't do this directly when generating resolv.conf in make_resolv_conf(), because

# we need to first save the resolv.conf with obtained values before we can call `ipcalc --hostname`.

# See bug 637763

    search="${1}"

    if need_hostname; then

        status=1

        if [ -n "${new_ip_address}" ]; then

            eval $(/bin/ipcalc --silent --hostname ${new_ip_address} ; echo "status=$?")

        elif [ -n "${new_ip6_address}" ]; then

            eval $(/bin/ipcalc --silent --hostname ${new_ip6_address} ; echo "status=$?")

        fi

        if [ ${status} -eq 0 ]; then

            domain=$(echo $HOSTNAME | cut -s -d "." -f 2-)

        fi

    else

          domain=$(hostname 2>/dev/null | cut -s -d "." -f 2-)

    fi

    if [ -n "${domain}" ] &&

       [ ! "${domain}" = "localdomain" ] &&

       [ ! "${domain}" = "localdomain6" ] &&

       [ ! "${domain}" = "(none)" ] &&

       [[ ! "${domain}" = *\ * ]]; then

       is_in="false"

       for s in ${search}; do

           if [ "${s}" = "${domain}" ] ||

              [ "${s}" = "${domain}." ]; then

              is_in="true"

           fi

       done

       if [ "${is_in}" = "false" ]; then

          # Add domain name to search list (#637763)

          sed -i -e "s/${search}/${search} ${domain}/" /etc/resolv.conf

       fi

    fi

}

make_resolv_conf() {

    [ "${PEERDNS}" = "no" ] && return

    if [ "${reason}" = "RENEW" ] &&

       [ "${new_domain_name}" = "${old_domain_name}" ] &&

       [ "${new_domain_name_servers}" = "${old_domain_name_servers}" ]; then

        return

    fi

    if [ -n "${new_domain_name}" ] ||

       [ -n "${new_domain_name_servers}" ] ||

       [ -n "${new_domain_search}" ]; then

        rscf="$(mktemp ${TMPDIR:-/tmp}/XXXXXX)"

        [[ -z "${rscf}" ]] && return

        echo "; generated by /usr/sbin/dhclient-script" > ${rscf}

        if [ -n "${SEARCH}" ]; then

            search="${SEARCH}"

        else

            if [ -n "${new_domain_search}" ]; then

                # Remove instaces of \032 (#450042)

                search="${new_domain_search//\\032/ }"

            elif [ -n "${new_domain_name}" ]; then

                # Note that the DHCP 'Domain Name Option' is really just a domain

                # name, and that this practice of using the domain name option as

                # a search path is both nonstandard and deprecated.

                search="${new_domain_name}"

            fi

        fi

        if [ -n "${search}" ]; then

            echo "search ${search}" >> $rscf

        fi

        if [ -n "${RES_OPTIONS}" ]; then

            echo "options ${RES_OPTIONS}" >> ${rscf}

        fi

        for nameserver in ${new_domain_name_servers} ; do

            echo "nameserver ${nameserver}" >> ${rscf}

        done

        change_resolv_conf ${rscf}

        rm -f ${rscf}

        if [ -n "${search}" ]; then

            eventually_add_hostnames_domain_to_search "${search}"

        fi

        fix_context /etc/resolv.conf

    elif [ -n "${new_dhcp6_name_servers}" ] ||

         [ -n "${new_dhcp6_domain_search}" ]; then

        rscf="$(mktemp ${TMPDIR:-/tmp}/XXXXXX)"

        [[ -z "${rscf}" ]] && return

        echo "; generated by /usr/sbin/dhclient-script" > ${rscf}

        if [ -n "${SEARCH}" ]; then

            search="${SEARCH}"

        else

            if [ -n "${new_dhcp6_domain_search}" ]; then

                search="${new_dhcp6_domain_search//\\032/ }"

            fi

        fi

        if [ -n "${search}" ]; then

            echo "search ${search}" >> $rscf

        fi

        if [ -n "${RES_OPTIONS}" ]; then

            echo "options ${RES_OPTIONS}" >> ${rscf}

        fi

        shopt -s nocasematch 

        for nameserver in ${new_dhcp6_name_servers} ; do

            # If the nameserver has a link-local address

            # add a <zone_id> (interface name) to it.

            if  [[ "$nameserver" =~ ^fe80:: ]]

            then

                zone_id="%${interface}"

            else

                zone_id=

            fi

            echo "nameserver ${nameserver}$zone_id" >> ${rscf}

        done

        shopt -u nocasematch 

        change_resolv_conf ${rscf}

        rm -f ${rscf}

        if [ -n "${search}" ]; then

            eventually_add_hostnames_domain_to_search "${search}"

        fi

        fix_context /etc/resolv.conf

    fi

}

exit_with_hooks() {

    exit_status="${1}"

    if [ -x ${ETCDIR}/dhclient-exit-hooks ]; then

        . ${ETCDIR}/dhclient-exit-hooks

    fi

    exit ${exit_status}

}

quad2num() {

    if [ $# -eq 4 ]; then

        let n="${1} << 24 | ${2} << 16 | ${3} << 8 | ${4}"

        echo "${n}"

        return 0

    else

        echo "0"

        return 1

    fi

}

ip2num() {

    IFS="." quad2num ${1}

}

num2ip() {

    let n="${1}"

    let o1="(n >> 24) & 0xff"

    let o2="(n >> 16) & 0xff"

    let o3="(n >> 8) & 0xff"

    let o4="n & 0xff"

    echo "${o1}.${o2}.${o3}.${o4}"

}

get_network_address() {

# get network address for the given IP address and (netmask or prefix)

    ip="${1}"

    nm="${2}"

    if [ -n "${ip}" -a -n "${nm}" ]; then

        if [[ "${nm}" = *.* ]]; then

            ipcalc -s -n ${ip} ${nm} | cut -d '=' -f 2

        else

            ipcalc -s -n ${ip}/${nm} | cut -d '=' -f 2

        fi

    fi

}

get_prefix() {

# get prefix for the given IP address and mask

    ip="${1}"

    nm="${2}"

    if [ -n "${ip}" -a -n "${nm}" ]; then

        ipcalc -s -p ${ip} ${nm} | cut -d '=' -f 2

    fi

}

class_bits() {

    let ip=$(IFS='.' ip2num $1)

    let bits=32

    let mask='255'

    for ((i=0; i <= 3; i++, 'mask<<=8')); do

        let v='ip&mask'

        if [ "$v" -eq 0 ] ; then

             let bits-=8

        else

             break

        fi

    done

    echo $bits

}

is_router_reachable() {

    # handle DHCP servers that give us a router not on our subnet

    router="${1}"

    routersubnet="$(get_network_address ${router} ${new_subnet_mask})"

    mysubnet="$(get_network_address ${new_ip_address} ${new_subnet_mask})"

    if [ ! "${routersubnet}" = "${mysubnet}" ]; then

        ip -4 route add ${router}/32 dev ${interface}

        if [ $? -eq 0 ]; then

            if ping -q -c1 -w2 -I ${interface} ${router}; then

                return 0

            else

                logmessage "DHCP router ${router} is unreachable on DHCP subnet ${mysubnet} router subnet ${routersubnet}"

                ip route del ${router}/32 dev ${interface}

                return 1

            fi

        else

            logmessage "failed to create host router for unreachable router ${router} not on subnet ${mysubnet}"

            return 1

        fi

    fi

    return 0

}

add_default_gateway() {

    router="${1}"

    if is_router_reachable ${router} ; then

        metric=""

        if [ $# -gt 1 ] && [ ${2} -gt 0 ]; then

            metric="metric ${2}"

        fi

        ip -4 route replace default via ${router} dev ${interface} ${metric}

        if [ $? -ne 0 ]; then

            logmessage "failed to create default route: ${router} dev ${interface} ${metric}"

            return 1

        else

            return 0

        fi

    fi

    return 1

}

execute_client_side_configuration_scripts() {

# execute any additional client side configuration scripts we have

    if [ "${1}" == "config" ] || [ "${1}" == "restore" ]; then

        for f in ${ETCDIR}/dhclient.d/*.sh ; do

            if [ -x ${f} ]; then

                subsystem="${f%.sh}"

                subsystem="${subsystem##*/}"

                . ${f}

                "${subsystem}_${1}"

            fi

        done

    fi

}

flush_dev() {

# Instead of bringing the interface down (#574568)

# explicitly clear the ARP cache and flush all addresses & routes.

    ip -4 addr flush dev ${1} >/dev/null 2>&1

    ip -4 route flush dev ${1} >/dev/null 2>&1

    ip -4 neigh flush dev ${1} >/dev/null 2>&1

}

dhconfig() {

    if [ -n "${old_ip_address}" ] && [ -n "${alias_ip_address}" ] &&

       [ ! "${alias_ip_address}" = "${old_ip_address}" ]; then

        # possible new alias, remove old alias first

        ip -4 addr del ${old_ip_address} dev ${interface} label ${interface}:0

    fi

    if [ -n "${old_ip_address}" ] &&

       [ ! "${old_ip_address}" = "${new_ip_address}" ]; then

        # IP address changed. Delete all routes, and clear the ARP cache.

        flush_dev ${interface}

    fi

    if [ "${reason}" = "BOUND" ] || [ "${reason}" = "REBOOT" ] ||

       [ ! "${old_ip_address}" = "${new_ip_address}" ] ||

       [ ! "${old_subnet_mask}" = "${new_subnet_mask}" ] ||

       [ ! "${old_network_number}" = "${new_network_number}" ] ||

       [ ! "${old_broadcast_address}" = "${new_broadcast_address}" ] ||

       [ ! "${old_routers}" = "${new_routers}" ] ||

       [ ! "${old_interface_mtu}" = "${new_interface_mtu}" ]; then

        ip -4 addr add ${new_ip_address}/${new_prefix} broadcast ${new_broadcast_address} dev ${interface} \

           valid_lft ${new_dhcp_lease_time} preferred_lft ${new_dhcp_lease_time} >/dev/null 2>&1

        ip link set dev ${interface} up

        # The 576 MTU is only used for X.25 and dialup connections

        # where the admin wants low latency.  Such a low MTU can cause

        # problems with UDP traffic, among other things.  As such,

        # disallow MTUs from 576 and below by default, so that broken

        # MTUs are ignored, but higher stuff is allowed (1492, 1500, etc).

        if [ -n "${new_interface_mtu}" ] && [ ${new_interface_mtu} -gt 576 ]; then

            ip link set dev ${interface} mtu ${new_interface_mtu}

        fi

        # static routes

        if [ -n "${new_classless_static_routes}" ] ||

           [ -n "${new_static_routes}" ]; then

            if [ -n "${new_classless_static_routes}" ]; then

                IFS=', |' static_routes=(${new_classless_static_routes})

            else

                IFS=', |' static_routes=(${new_static_routes})

            fi

            route_targets=()

            for((i=0; i<${#static_routes[@]}; i+=2)); do

                target=${static_routes[$i]}

                if [ -n "${new_classless_static_routes}" ]; then

                    if [ ${target} = "0" ]; then

                        # If the DHCP server returns both a Classless Static Routes option and

                        # a Router option, the DHCP client MUST ignore the Router option. (RFC3442)

                        new_routers=""

                        prefix="0"

                    else

                        prefix=${target%%.*}

                        target=${target#*.}

                        IFS="." target_arr=(${target})

                        unset IFS

                        ((pads=4-${#target_arr[@]}))

                        for j in $(seq $pads); do

                            target="${target}.0"

                        done

                        # Client MUST zero any bits in the subnet number where the corresponding bit in the mask is zero.

                        # In other words, the subnet number installed in the routing table is the logical AND of

                        # the subnet number and subnet mask given in the Classless Static Routes option. (RFC3442)

                        target="$(get_network_address ${target} ${prefix})"

                    fi

                else

                    prefix=$(class_bits ${target})

                fi

                gateway=${static_routes[$i+1]}

                # special case 0.0.0.0 to allow static routing for link-local addresses

                # (including IPv4 multicast) which will not have a next-hop (#769463, #787318)

                if [ "${gateway}" = "0.0.0.0" ]; then

                    valid_gateway=0

                    scope='scope link'

                else

                    is_router_reachable ${gateway}

                    valid_gateway=$?

                    scope=''

                fi

                if [ ${valid_gateway} -eq 0 ]; then

                    metric=''

                    for t in ${route_targets[@]}; do

                        if [ ${t} = ${target} ]; then

                            if [ -z "${metric}" ]; then

                                metric=1

                            else

                                ((metric=metric+1))

                            fi

                        fi

                    done

                    if [ -n "${metric}" ]; then

                        metric="metric ${metric}"

                    fi

                    ip -4 route replace ${target}/${prefix} proto static via ${gateway} dev ${interface} ${metric} ${scope}

                    if [ $? -ne 0 ]; then

                        logmessage "failed to create static route: ${target}/${prefix} via ${gateway} dev ${interface} ${metric}"

                    else

                        route_targets=(${route_targets[@]} ${target})

                    fi

                fi

            done

        fi

        # gateways

        if [[ ( "${DEFROUTE}" != "no" ) &&

              (( -z "${GATEWAYDEV}" ) || ( "${GATEWAYDEV}" = "${interface}" )) ]]; then

            if [[ ( -z "$GATEWAY" ) ||

                  (( -n "$DHCLIENT_IGNORE_GATEWAY" ) && ( "$DHCLIENT_IGNORE_GATEWAY" = [Yy]* )) ]]; then

                metric="${METRIC:-}"

                let i="${METRIC:-0}"

                default_routers=()

                for router in ${new_routers} ; do

                    added_router=-

                    for r in ${default_routers[@]} ; do

                        if [ "${r}" = "${router}" ]; then

                            added_router=1

                        fi

                    done

                    if [ -z "${router}" ] ||

                       [ "${added_router}" = "1" ] ||

                       [ $(IFS=. ip2num ${router}) -le 0 ] ||

                       [[ ( "${router}" = "${new_broadcast_address}" ) &&

                          ( "${new_subnet_mask}" != "255.255.255.255" ) ]]; then

                        continue

                    fi

                    default_routers=(${default_routers[@]} ${router})

                    add_default_gateway ${router} ${metric}

                    let i=i+1

                    metric=${i}

                done

            elif [ -n "${GATEWAY}" ]; then

                routersubnet=$(get_network_address ${GATEWAY} ${new_subnet_mask})

                mysubnet=$(get_network_address ${new_ip_address} ${new_subnet_mask})

                if [ "${routersubnet}" = "${mysubnet}" ]; then

                    ip -4 route replace default via ${GATEWAY} dev ${interface}

                fi

            fi

        fi

    else # RENEW||REBIND - only update address lifetimes

        ip -4 addr change ${new_ip_address}/${new_prefix} broadcast ${new_broadcast_address} dev ${interface} \

           valid_lft ${new_dhcp_lease_time} preferred_lft ${new_dhcp_lease_time} >/dev/null 2>&1

    fi

    if [ ! "${new_ip_address}" = "${alias_ip_address}" ] &&

       [ -n "${alias_ip_address}" ]; then

        # Reset the alias address (fix: this should really only do this on changes)

        ip -4 addr flush dev ${interface} label ${interface}:0 >/dev/null 2>&1

        ip -4 addr add ${alias_ip_address}/${alias_prefix} broadcast ${alias_broadcast_address} dev ${interface} label ${interface}:0

        ip -4 route replace ${alias_ip_address}/32 dev ${interface}

    fi

    # After dhclient brings an interface UP with a new IP address, subnet mask, 

    # and routes, in the REBOOT/BOUND states -> search for "dhclient-up-hooks".

    if [ "${reason}" = "BOUND" ] || [ "${reason}" = "REBOOT" ] ||

       [ ! "${old_ip_address}" = "${new_ip_address}" ] ||

       [ ! "${old_subnet_mask}" = "${new_subnet_mask}" ] ||

       [ ! "${old_network_number}" = "${new_network_number}" ] ||

       [ ! "${old_broadcast_address}" = "${new_broadcast_address}" ] ||

       [ ! "${old_routers}" = "${new_routers}" ] ||

       [ ! "${old_interface_mtu}" = "${new_interface_mtu}" ]; then

        if [ -x ${ETCDIR}/dhclient-${interface}-up-hooks ]; then

            . ${ETCDIR}/dhclient-${interface}-up-hooks

        elif [ -x ${ETCDIR}/dhclient-up-hooks ]; then

            . ${ETCDIR}/dhclient-up-hooks

        fi

    fi

    make_resolv_conf

    if [ -n "${new_host_name}" ] && need_hostname; then

        hostname ${new_host_name} || echo "See -nc option in dhclient(8) man page."

    fi

    if [[ ( "${DHCP_TIME_OFFSET_SETS_TIMEZONE}" = [yY1]* ) &&

          ( -n "${new_time_offset}" ) ]]; then

        # DHCP option "time-offset" is requested by default and should be

        # handled.  The geographical zone abbreviation cannot be determined

        # from the GMT offset, but the $ZONEINFO/Etc/GMT$offset file can be

        # used - note: this disables DST.

        ((z=new_time_offset/3600))

        ((hoursWest=$(printf '%+d' $z)))

        if (( $hoursWest < 0 )); then

            # tzdata treats negative 'hours west' as positive 'gmtoff'!

            ((hoursWest*=-1))

        fi

        tzfile=/usr/share/zoneinfo/Etc/GMT$(printf '%+d' ${hoursWest})

        if [ -e ${tzfile} ]; then

            cp -fp ${tzfile} /etc/localtime

            touch /etc/localtime

            fix_context /etc/localtime

        fi

    fi

    execute_client_side_configuration_scripts "config"

}

# Section 18.1.8. (Receipt of Reply Messages) of RFC 3315 says:

# The client SHOULD perform duplicate address detection on each of

# the addresses in any IAs it receives in the Reply message before

# using that address for traffic.

add_ipv6_addr_with_DAD() {

            ip -6 addr add ${new_ip6_address}/${new_ip6_prefixlen} \

                dev ${interface} scope global valid_lft ${new_max_life} \

                                          preferred_lft ${new_preferred_life}

            # repeatedly test whether newly added address passed

            # duplicate address detection (DAD)

            for i in $(seq 5); do

                sleep 1 # give the DAD some time

                # tentative flag == DAD is still not complete

                tentative=$(ip -6 addr show dev ${interface} tentative \

                           | grep ${new_ip6_address}/${new_ip6_prefixlen})

                # dadfailed flag == address is already in use somewhere else

                dadfailed=$(ip -6 addr show dev ${interface} dadfailed \

                           | grep ${new_ip6_address}/${new_ip6_prefixlen})

                if [ -n "${dadfailed}" ] ; then

                    #ip -6 addr del ${new_ip6_address}/${new_ip6_prefixlen} dev ${interface}

                    exit_with_hooks 3

                fi

                if [ -z "${tentative}" ] ; then

                    # DAD is over

                    return 0

                fi

            done

}

dh6config() {

    if [ -n "${old_ip6_prefix}" ] ||

       [ -n "${new_ip6_prefix}" ]; then

        echo Prefix ${reason} old=${old_ip6_prefix} new=${new_ip6_prefix}

        exit_with_hooks 0

    fi

    case "${reason}" in

        BOUND6)

            if [ -z "${new_ip6_address}" ] ||

               [ -z "${new_ip6_prefixlen}" ]; then

                exit_with_hooks 2

            fi

            add_ipv6_addr_with_DAD

            make_resolv_conf

            ;;

        RENEW6|REBIND6)

            if [ -z "${new_ip6_address}" ] ||

               [ -z "${new_ip6_prefixlen}" ]; then

                exit_with_hooks 2

            fi

            if [  ! "${new_ip6_address}" = "${old_ip6_address}" ]; then

                add_ipv6_addr_with_DAD

            else # only update address lifetimes

                ip -6 addr change ${new_ip6_address}/${new_ip6_prefixlen} \

                   dev ${interface} scope global valid_lft ${new_max_life} \

                                             preferred_lft ${new_preferred_life}

            fi

            if [ ! "${new_dhcp6_name_servers}" = "${old_dhcp6_name_servers}" ] ||

               [ ! "${new_dhcp6_domain_search}" = "${old_dhcp6_domain_search}" ]; then

                make_resolv_conf

            fi

            ;;

        DEPREF6)

            if [ -z "${new_ip6_prefixlen}" ]; then

                exit_with_hooks 2

            fi

            ip -6 addr change ${new_ip6_address}/${new_ip6_prefixlen} \

                dev ${interface} scope global preferred_lft 0

            ;;

    esac

    execute_client_side_configuration_scripts "config"

}

#

# ### MAIN

#

if [ -x ${ETCDIR}/dhclient-enter-hooks ]; then

    exit_status=0

    # dhclient-enter-hooks can abort dhclient-script by setting

    # the exit_status variable to a non-zero value

    . ${ETCDIR}/dhclient-enter-hooks

    if [ ${exit_status} -ne 0 ]; then

        exit ${exit_status}

    fi

fi

if [ ! -r /etc/sysconfig/network-scripts/network-functions ]; then

    echo "Missing /etc/sysconfig/network-scripts/network-functions, exiting." >&2

    exit 1

fi

if [ ! -r /etc/rc.d/init.d/functions ]; then

    echo "Missing /etc/rc.d/init.d/functions, exiting." >&2

    exit 1

fi

. /etc/sysconfig/network-scripts/network-functions

. /etc/rc.d/init.d/functions

if [ -f /etc/sysconfig/network ]; then

    . /etc/sysconfig/network

fi

if [ -f /etc/sysconfig/networking/network ]; then

    . /etc/sysconfig/networking/network

fi

cd /etc/sysconfig/network-scripts

CONFIG="${interface}"

need_config ${CONFIG}

source_config >/dev/null 2>&1

new_prefix="$(get_prefix ${new_ip_address} ${new_subnet_mask})"

old_prefix="$(get_prefix ${old_ip_address} ${old_subnet_mask})"

alias_prefix="$(get_prefix ${alias_ip_address} ${alias_subnet_mask})"

case "${reason}" in

    MEDIUM|ARPCHECK|ARPSEND)

        # Do nothing

        exit_with_hooks 0

        ;;

    PREINIT)

        if [ -n "${alias_ip_address}" ]; then

            # Flush alias, its routes will disappear too.

            ip -4 addr flush dev ${interface} label ${interface}:0 >/dev/null 2>&1

        fi

        # upstream dhclient-script removes (ifconfig $interface 0 up) old adresses in PREINIT,

        # but we sometimes (#125298) need (for iSCSI/nfs root to have a dhcp interface) to keep the existing ip

        # flush_dev ${interface}

        ip link set dev ${interface} up

        if [ -n "${DHCLIENT_DELAY}" ] && [ ${DHCLIENT_DELAY} -gt 0 ]; then

            # We need to give the kernel some time to get the interface up.

            sleep ${DHCLIENT_DELAY}

        fi

        exit_with_hooks 0

        ;;

    PREINIT6)

        # ensure interface is up

        ip link set dev ${interface} up

        # remove any stale addresses from aborted clients

        ip -6 addr flush dev ${interface} scope global permanent

        exit_with_hooks 0

        ;;

    BOUND|RENEW|REBIND|REBOOT)

        if [ -z "${interface}" ] || [ -z "${new_ip_address}" ]; then

            exit_with_hooks 2

        fi

        if arping -D -q -c2 -I ${interface} ${new_ip_address}; then

            dhconfig

            exit_with_hooks 0

        else  # DAD failed, i.e. address is already in use

            ARP_REPLY=$(arping -D -c2 -I ${interface} ${new_ip_address} | grep reply | awk '{print toupper($5)}' | cut -d "[" -f2 | cut -d "]" -f1)