#!/bin/bash
#
# dhclient-script: Network interface configuration script run by
#                  dhclient based on DHCP client communication
#
# Copyright (C) 2008, 2009, 2010  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>
#
# ----------
# 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
SAVEDIR=/var/lib/dhclient

LOGFACILITY="local7"
LOGLEVEL="notice"

ETCDIR="/etc/dhcp"

logmessage() {
    msg="${1}"
    logger -p ${LOGFACILITY}.${LOGLEVEL} -t "NET" "dhclient: ${msg}"
}

fix_context() {
    if [ -x /sbin/restorecon ]; then
        /sbin/restorecon ${1} >/dev/null 2>&1
    fi
}

save_previous() {
    origfile="${1}"
    savefile="${SAVEDIR}/${origfile##*/}.predhclient.${interface}"

    if [ ! -d ${SAVEDIR} ]; then
        mkdir -p ${SAVEDIR}
    fi

    if [ -e ${origfile} ]; then
        contents="$(< ${origfile})"
        echo "${contents}" > ${savefile}
        rm -f ${origfile}
    else
        echo > ${savefile}
    fi

    fix_context ${savefile}
}

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 "${new_domain_search}" ]; then
        save_previous /etc/resolv.conf
        rscf="$(mktemp /tmp/XXXXXX)"
        echo "; generated by /sbin/dhclient-script" > ${rscf}

        if [ -n "${SEARCH}" ]; then
            echo "search ${SEARCH}" >> $rscf
        else
            if [ -n "${new_domain_search}" ]; then
                echo "search ${new_domain_search//\\032/ }" >> ${rscf}
            elif [ -n "${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.
                echo "search ${new_domain_name//\\032/ }" >> ${rscf}
            fi
        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}

        fix_context /etc/resolv.conf
    elif [ -n "${new_dhcp6_name_servers}" ] ||
         [ -n "${new_dhcp6_domain_search}" ]; then
        save_previous /etc/resolv.conf
        rscf="$(mktemp /tmp/XXXXXX)"
        echo "; generated by /sbin/dhclient-script" > ${rscf}

        if [ -n "${SEARCH}" ]; then
            echo "search ${SEARCH}" >> $rscf
        else
            if [ -n "${new_dhcp6_domain_search}" ]; then
                echo "search ${new_dhcp6_domain_search//\\032/ }" >> ${rscf}
            fi
        fi

        if [ -n "${RES_OPTIONS}" ]; then
            echo "options ${RES_OPTIONS}" >> ${rscf}
        fi

        for nameserver in ${new_dhcp6_name_servers} ; do
            echo "nameserver ${nameserver}" >> ${rscf}
        done

        change_resolv_conf ${rscf}
        rm -f ${rscf}

        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}"
}

mask() {
    ip="${1}"
    m="${2}"
    let ip="$(IFS="." ip2num ${ip})"
    let m="$(IFS="." ip2num ${m})"
    let n="ip & m"
    num2ip ${n}
}

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="${1}"
    routersubnet="$(mask ${router} ${new_subnet_mask})"
    mysubnet="$(mask ${new_ip_address} ${new_subnet_mask})"
    unreachable=0

    if [ ! "${routersubnet}" = "${mysubnet}" ]; then
        unreachable=1
        if arping -f -q -I ${interface} -w2 ${router}; then
            ip -4 route add ${router}/32 dev ${interface}
            if [ $? -eq 0 ]; then
                unreachable=0
            else
                logmessage "failed to create host router for unreachable router ${router} not on subnet ${mysubnet}"
            fi
        else
            unreachable=1
            logmessage "DHCP router ${router} is unreachable on DHCP subnet ${mysubnet} router subnet ${routersubnet}"
        fi
    fi

    return ${unreachable}
}

add_default_gateway() {
    router="${1}"
    metric=""

    if [ $# -gt 1 ] && [ ${2} -gt 0 ]; then
        metric="metric ${2}"
    fi

    if is_router_reachable ${router} ; then
        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
}

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}:0
    fi

    if [ -n "${old_ip_address}" ] &&
       [ ! "${old_ip_address}" = "${new_ip_address}" ]; then
        # IP address changed.  Bringing down the interface will delete all
        # routes, and clear the ARP cache.
        ip -4 addr flush dev ${interface} >/dev/null 2>&1
    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}
        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 ${interface} mtu ${new_interface_mtu}
        fi

        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

        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 "${GATEWAY}" ]; then
                routersubnet=$(mask ${GATEWAY} ${new_subnet_mask})
                mysubnet=$(mask ${new_ip_address} ${new_subnet_mask})

                if [ "${routersubnet}" = "${mysubnet}" ]; then
                    ip -4 route replace default via ${GATEWAY} dev ${interface}
                fi
            fi
        fi

        # static routes
        if [ -n "${new_static_routes}" ]; then
            IFS=', |' static_routes=(${new_static_routes})
            route_targets=()

            for((i=0; i<${#static_routes[@]}; i+=2)); do
                target=${static_routes[$i]}
                gateway=${static_routes[$i+1]}
                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

                if is_router_reachable ${gateway}; then
                    ip -4 route replace ${target}/$(class_bits ${target}) via ${gateway} dev ${interface} ${metric}

                    if [ $? -ne 0 ]; then
                        logmessage "failed to create static route: ${target}/$(class_bits ${target}) via ${gateway} dev ${interface} ${metric}"
                    else
                        route_targets=(${route_targets[@]} ${target})
                    fi
                fi
            done
        fi
    fi

    if [ ! "${new_ip_address}" = "${alias_ip_address}" ] &&
       [ -n "${alias_ip_address}" ]; then
        ip -4 addr flush dev ${interface}:0 >/dev/null 2>&1
        ip -4 addr add ${alias_ip_address}/${alias_prefix} dev ${interface}:0
        ip -4 route replace ${alias_ip_address}/32 dev ${interface}:0
    fi

    make_resolv_conf

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

    if [ -n "${DHCP_TIME_OFFSET_SETS_TIMEZONE}" ] &&
       [[ "${DHCP_TIME_OFFSET_SETS_TIMEZONE}" = [yY1]* ]]; then
        if [ -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
                save_previous /etc/localtime
                cp -fp ${tzfile} /etc/localtime
                touch /etc/localtime
                fix_context /etc/localtime
            fi
        fi
    fi

    # execute any additional client side configuration scripts we have
    if [ -d ${ETCDIR}/dhclient.d ]; then
        for f in ${ETCDIR}/dhclient.d/*.sh ; do
            if [ -x ${f} ]; then
                subsystem="${f%.sh}"
                subsystem="${subsystem##*/}"
                . ${f}
                "${subsystem}_config"
            fi
        done
    fi
}

# 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

            # 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 or failed
                duplicate=$(ip -6 addr show dev ${interface} tentative \
                              | grep ${new_ip6_address}/${new_ip6_prefixlen})

                # if there's no tentative flag, address passed DAD
                if [ -z "${duplicate}" ]; then
                    break
                fi
            done

            # if there's still tentative flag = address didn't pass DAD = 
            # = it's duplicate = remove it
            if [ -n "${duplicate}" ]; then
                ip -6 addr del ${new_ip6_address}/${new_ip6_prefixlen} dev ${interface}
                exit_with_hooks 3
            fi
}

dh6config() {
    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 [ -n "${new_ip6_prefixlen}" ] &&
               [ -n "${new_ip6_address}" ] &&
               [  ! "${new_ip6_address}" = "${old_ip6_address}" ]; then
                add_ipv6_addr_with_DAD
            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 any additional client side configuration scripts we have
    if [ -d ${ETCDIR}/dhclient.d ]; then
        for f in ${ETCDIR}/dhclient.d/*.sh ; do
            if [ -x ${f} ]; then
                subsystem="${f%.sh}"
                subsystem="${subsystem##*/}"
                . ${f}
                "${subsystem}_config"
            fi
        done
    fi
}

get_prefix() {
    ip="${1}"
    nm="${2}"

    if [ -n "${ip}" -a -n "${nm}" ]; then
        ipcalc -s -p ${ip} ${nm} | cut -d '=' -f 2
    fi
}


#
# ### 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="ifcfg-${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)
        # Linux doesn't handle mediums (media)
        exit_with_hooks 0
        ;;

    PREINIT)
        if [ -n "${alias_ip_address}" ]; then
            # Bring down alias interface, its routes will disappear too.
            ip link set ${interface}:0 down
        fi

        if [ "${keep_old_ip}" = "yes" ]; then
            ip link set ${interface} up
        else
            ip -4 addr flush dev ${interface} >/dev/null 2>&1
            ip link set ${interface} up
        fi

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

        exit_with_hooks 0
        ;;

    PREINIT6)
        # ensure interface is up
        ip link set ${interface} up

        # remove any stale addresses from aborted clients
        ip -6 addr flush dev ${interface} scope global permanent

        exit_with_hooks 0
        ;;

    ARPCHECK|ARPSEND)
        if [ -z "${new_ip_address}" ] || [ -z "${interface}" ] ||
           arping -q -f -c 2 -w 3 -D -I ${interface} ${new_ip_address}; then
            exit_with_hooks 0
        else
            exit_with_hooks 1
        fi
        ;;

    BOUND|RENEW|REBIND|REBOOT)
        dhconfig
        exit_with_hooks 0
        ;;

    BOUND6|RENEW6|REBIND6|DEPREF6)
        dh6config
        exit_with_hooks 0
        ;;

    EXPIRE6|RELEASE6|STOP6)
        if [ -z "${old_ip6_address}" ] || [ -z "${old_ip6_prefixlen}" ]; then
            exit_with_hooks 2
        fi

        ip -6 addr del ${old_ip6_address}/${old_ip6_prefixlen} \
            dev ${interface}

        # execute any additional client side configuration scripts we have
        if [ -d ${ETCDIR}/dhclient.d ]; then
            for f in ${ETCDIR}/dhclient.d/*.sh ; do
                if [ -x ${f} ]; then
                    subsystem="${f%.sh}"
                    subsystem="${subsystem##*/}"
                    . ${f}
                    "${subsystem}_restore"
                fi
            done
        fi

        if [ -x ${ETCDIR}/dhclient-${interface}-down-hooks ]; then
            . ${ETCDIR}/dhclient-${interface}-down-hooks
        elif [ -x ${ETCDIR}/dhclient-down-hooks ]; then
            . ${ETCDIR}/dhclient-down-hooks
        fi

        exit_with_hooks 0
        ;;

    EXPIRE|FAIL|RELEASE|STOP)
        # only restore config files if there are no other dhclient processes
        # running (#306381)
        any_other_clients="$(ps -eo pid,ppid,comm | grep dhclient | grep -v ${PPID})"
        if [ -n "${any_other_clients}" ]; then
            if [ -f ${SAVEDIR}/resolv.conf.predhclient.${interface} ]; then
                change_resolv_conf ${SAVEDIR}/resolv.conf.predhclient.${interface}
                rm -f ${SAVEDIR}/resolv.conf.predhclient.${interface}
            fi

            if [ -n "${DHCP_TIME_OFFSET_SETS_TIMEZONE}" ] &&
               [[ "${DHCP_TIME_OFFSET_SETS_TIMEZONE}" = [yY1]* ]]; then
                if [ -e ${SAVEDIR}/localtime.predhclient.${interface} ]; then
                    rm -f /etc/localtime
                    contents="$(< ${SAVEDIR}/localtime.predhclient.${interface})"
                    echo "${contents}" > /etc/localtime
                    rm -f ${SAVEDIR}/localtime.predhclient.${interface}
                    touch /etc/localtime
                    fix_context /etc/localtime
                fi
            fi
        fi

        # execute any additional client side configuration scripts we have
        if [ -d ${ETCDIR}/dhclient.d ]; then
            for f in ${ETCDIR}/dhclient.d/*.sh ; do
                if [ -x ${f} ]; then
                    subsystem="${f%.sh}"
                    subsystem="${subsystem##*/}"
                    . ${f}
                    "${subsystem}_restore"
                fi
            done
        fi

        if [ -x ${ETCDIR}/dhclient-${interface}-down-hooks ]; then
            . ${ETCDIR}/dhclient-${interface}-down-hooks
        elif [ -x ${ETCDIR}/dhclient-down-hooks ]; then
            . ${ETCDIR}/dhclient-down-hooks
        fi

        if [ -n "${alias_ip_address}" ]; then
            # Turn off alias interface
            ip link set ${interface}:0 down
        fi

        if [ -n "${old_ip_address}" ]; then
            # Shut down interface, which will delete routes and clear arp cache.
            ip -4 addr flush dev ${interface} >/dev/null 2>&1
            ip link set ${interface} down
        fi

        if [ -n "${alias_ip_address}" ]; then
            ip -4 addr add ${alias_ip_address}/${alias_prefix} dev ${interface}:0
            ip -4 route replace ${alias_ip_address}/32 ${interface}:0
        fi

        exit_with_hooks 0
        ;;

    TIMEOUT)
        if [ -n "${new_routers}" ]; then
            if [ -n "${alias_ip_address}" ]; then
                ip -4 addr flush dev ${interface}:0 >/dev/null 2>&1
            fi

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

            if ping -q -c 1 -w 10 -I ${interface} ${1}; then
                dhconfig
                exit_with_hooks 0
            fi

            ip -4 addr flush dev ${interface} >/dev/null 2>&1
            ip link set ${interface} down
            exit_with_hooks 1
        else
            exit_with_hooks 1
        fi
        ;;

    *)
        logmessage "unhandled state: ${reason}"
        exit_with_hooks 1
        ;;
esac

exit_with_hooks 0