dhcp/linux

#!/bin/bash
# dhclient-script for Linux. Dan Halbert, March, 1997.
# Updated for Linux 2.[12] by Brian J. Murrell, January 1999.
# No guarantees about this. I'm a novice at the details of Linux
# networking.

# Notes:

# 0. This script is based on the netbsd script supplied with dhcp-970306.

# 1. ifconfig down apparently deletes all relevant routes and flushes
# the arp cache, so this doesn't need to be done explicitly.

# 2. The alias address handling here has not been tested AT ALL.
# I'm just going by the doc of modern Linux ip aliasing, which uses
# notations like eth0:0, eth0:1, for each alias.

# 3. I have to calculate the network address, and calculate the broadcast
# address if it is not supplied. This might be much more easily done
# by the dhclient C code, and passed on.

if [ -n "${dhc_dbus}" ]; then
   /bin/dbus-send \
       --system \
       --dest=com.redhat.dhcp \
       --type=method_call \
       /com/redhat/dhcp/$interface \
       com.redhat.dhcp.set \
       'string:'"`env | /bin/egrep -v '^(PATH|SHLVL|_|PWD|dhc_dbus)\='`";
       if (( ( dhc_dbus & 31 ) == 31 )); then
	   exit 0;
       fi;
fi;

function save_previous() {
  if [ -e $1 ]; then
    /bin/mv $1 $1.predhclient
  else
    echo ''> $1.predhclient 
  fi
}

make_resolv_conf() {
  if [ "${PEERDNS}" == "no" ]; then  
      return 
  fi

  if [ x$reason == xRENEW ] &&
     [ "$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" ]; then
    cp -fp /etc/resolv.conf /etc/resolv.conf.predhclient
    rscf=`mktemp /tmp/XXXXXX`;
    echo '; generated by /sbin/dhclient-script' > $rscf
    if [ -n "$SEARCH" ]; then
 	echo search $SEARCH >> $rscf
    else
	if [ -n "$new_domain_name" ]; then
 	    echo search $new_domain_name >> $rscf
        fi
    fi
    for nameserver in $new_domain_name_servers; do
      echo nameserver $nameserver >> $rscf
    done
    change_resolv_conf $rscf
    rm -f $rscf
  fi
}

# Must be used on exit.   Invokes the local dhcp client exit hooks, if any.
exit_with_hooks() {
  exit_status=$1
  if [ -f /etc/dhclient-exit-hooks ]; then
    . /etc/dhclient-exit-hooks
  fi
# probably should do something with exit status of the local script
  exit $exit_status
}

# Invoke the local dhcp client enter hooks, if they exist.
if [ -f /etc/dhclient-enter-hooks ]; then
  exit_status=0
  . /etc/dhclient-enter-hooks
  # allow the local script to abort processing of this state
  # local script must set exit_status variable to nonzero.
  if [ $exit_status -ne 0 ]; then
    exit $exit_status
  fi
fi

# Import Red Hat Linux configuration
cd /etc/sysconfig/network-scripts;
. /etc/sysconfig/network-scripts/network-functions
. /etc/rc.d/init.d/functions

[ -f ../network ] && . ../network
[ -f ../networking/network ] && . ../networking/network

CONFIG=$interface

need_config ${CONFIG}

if [ -f "${CONFIG}" ]; then 
    source_config
else
    echo $"$0: configuration for $interface not found. Continuing with defaults." >&2
fi

source_config

release=`uname -r`
relmajor=`echo $release |/bin/cut -f1 -d'.'`
relminor=`echo $release |/bin/cut -f2 -d'.'`

# simple IP arithmetic functions:

function quad2num()
{
    if [ $# -eq 4 ]; then
       let n="$1<<24|$2<<16|$3<<8|$4"
       echo $n;
       return 0;
    fi
    echo '0';
    return 1;
}

function ip2num()
{
    IFS='.' quad2num $1;
}

function 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;
}

function mask()
{   
    ip=$1
    m=$2
    let ip=`IFS='.' ip2num $ip`;
    let m=`IFS='.' ip2num $m`;
    let n='ip&m';
    num2ip $n;
}

function mask_bits()
{
    ip=$1
    let ip=`IFS='.' ip2num $ip`;
    let bits=0
    for ((bit=1; '((ip&bit)==0) && (bits < 32)'; 'bit<<=1')) do
        let bits+=1
    done
    let n_bits=32-bits
    echo $n_bits
}

function 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;
}

function routerReachable()
{ # Handle silly 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 /sbin/arping -f -q -I $interface -w2 $router; then
	    /sbin/ip route add ${router}/32 dev $interface
	    if [ $? -eq 0 ]; then
		unreachable=0
	    else
		/usr/bin/logger -p local7.notice -t "NET"  "dhclient: failed to create host route for unreachable router $router not on subnet $mySubnet";
	    fi
	else
	    unreachable=1
	    if [ -x /usr/bin/logger ]; then
		/usr/bin/logger -p local7.notice -t "NET"  "dhclient: DHCP router $router is unreachable on DHCP subnet $mySubnet router subnet $routerSubnet";
	    fi;
	fi;
    fi;
    return $unreachable;
}

function add_default_gateway()
{
    router=$1
    metric=''
    if [ $# -gt 1 ] && [ "$2" -gt 0 ]; then 
	metric="metric $2";
    fi;    
    if routerReachable $router ; then
	/sbin/ip route replace default via $router dev $interface $metric;
	if [ $? -ne 0 ]; then 
	    /usr/bin/logger -p local7.notice -t "NET"  'dhclient: failed to create default route: '$router dev $interface $metric;
	    return 1;
	else
	    return 0;
	fi;
    fi;
    return 1;
}

function dhconfig()
{
    if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 2 ) != 2 )); then
	if [ x$old_ip_address != x ] && [ x$alias_ip_address != x ] && \
		[ x$alias_ip_address != x$old_ip_address ]; then
         # Possible new alias. Remove old alias.
	    ifconfig $interface:0- inet 0
	fi

	if [ x$old_ip_address != x ] && [ x$old_ip_address != x$new_ip_address ]; then
        # IP address changed. Bringing down the interface will delete all routes,
        # and clear the ARP cache.
	    ifconfig $interface inet 0 down
	fi
    fi
    if [ x$reason = xBOUND ] || [ x$reason = xREBOOT ] ||
       [ x$old_ip_address  != x$new_ip_address ] ||
       [ x$old_subnet_mask != x$new_subnet_mask ] ||
       [ x$new_network_number != x$new_network_number ] ||
       [ x$old_broadcast_address != x$new_broadcast_address ] ||
       [ "x$old_routers" != "x$new_routers" ] ||
       [ x$old_interface_mtu != x$new_interface_mtu ] ; then
	if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 2 ) != 2 )); then
	    ifconfig $interface inet $new_ip_address $new_subnet_arg \
		$new_broadcast_arg
	    if [ -n "$new_interface_mtu" ]; then
		/sbin/ip link set $interface mtu $new_interface_mtu;
	    fi;
	    if [ -x /etc/dhclient-${interface}-up-hooks ]; then
		. /etc/dhclient-${interface}-up-hooks;
	    elif [ -x /etc/dhclient-up-hooks ]; then
		. /etc/dhclient-up-hooks;
	    fi;
	fi;
	
	if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 4 ) != 4 )); then
	    prefix_bits=`mask_bits $new_subnet_mask`
            # Add a network route to the computed network address.
	    if [ $relmajor -lt 2 ] || \
		( [ $relmajor -eq 2 ] && [ $relminor -eq 0 ] ); then
		/sbin/ip route replace ${new_network_number}/${prefix_bits} dev $interface
		if [ $added_old_broadcast_route -eq 1 ]; then
		   /sbin/ip route del default;
		fi;
	    fi;
	    if [[  ( ( -z "$GATEWAYDEV" )  || ( "$GATEWAYDEV" = "$interface" ) ) && ( ( -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=0
		    for r in ${default_routers[@]}; do
			if [ "$r" == "$router" ]; then
			    added_router=1;
                        fi;
		    done
		    if [ -z "$router" ] || [ "$added_router" -eq 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 [[ ( ( -z "$GATEWAYDEV" ) || ( "$GATEWAYDEV" = "$interface" ) ) && ( -n "$GATEWAY" ) ]]; then
		routerSubnet=`mask $GATEWAY $new_subnet_mask`
		mySubnet=`mask $new_ip_address $new_subnet_mask`
		if [ "$routerSubnet" = "$mySubnet" ]; then
		    /sbin/ip route replace default via $GATEWAY dev $interface 
		fi;
	    fi;
            # static routes
	    if [ "x$new_static_routes" != x ]; 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 routerReachable $gateway; then
			/sbin/ip route replace ${target}/`class_bits $target` via ${gateway} dev $interface ${metric}
			if [ $? -ne 0 ]; then
			   /usr/bin/logger -p local7.notice -t 'NET' 'dhclient: failed to create static route:' ${target}/`class_bits $target` via ${gateway} dev $interface ${metric};			
			else			    
 			   route_targets=(${route_targets[@]} $target);
			fi;
		    fi;
		done
	    fi
	fi
    fi
    if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 2 ) != 2 )); then
	if [ x$new_ip_address != x$alias_ip_address ] && [ x$alias_ip_address != x ];
	    then
	    ifconfig $interface:0- inet 0
	    ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
	    /sbin/ip route replace ${alias_ip_address}/32 dev $interface:0
	fi
    fi
    if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 1 ) != 1 )); then
	make_resolv_conf

	if [ -n "$new_host_name" ] && need_hostname; then
	    hostname $new_host_name
	fi
    fi;
    if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 8 ) != 8 )); then
	if [ "${PEERNIS}" = no ]; then
	    :
	elif [ -n "$new_nis_domain" ]; then
	    domainname "$new_nis_domain"
	    save_previous /etc/yp.conf
	    let contents=0
	    echo '# generated by /sbin/dhclient-script' > /etc/yp.conf
	    if [ -n "$new_nis_servers" ]; then
		for I in $new_nis_servers; do
		    echo "domain $new_nis_domain server $I" >> /etc/yp.conf
		    let contents=contents+1
		done
	    else
		echo "domain $new_nis_domain broadcast" >> /etc/yp.conf
		let contents=contents+1
	    fi
	    level=`/sbin/runlevel`
	    level=${level##*\ }
	    if [ "$level" = "unknown" ]; then
		level=1;
	    fi
	    if [ $contents -gt 0 ] && [[ "$level" = [0-6] ]] && /sbin/chkconfig --level=$level ypbind >/dev/null 2>&1 && [ -r /var/run/ypbind.pid ] && yppid=`cat /var/run/ypbind.pid` && [ -d /proc/${yppid} ] && [ "`if [ -x /sbin/busybox ]; then /sbin/busybox readlink /proc/${yppid}/exe; else echo /sbin/ypbind; fi`" = "/sbin/ypbind" ]; then
	       kill -HUP $yppid;
	    fi
	elif [ -n "$new_nis_servers" ]; then
	    save_previous /etc/yp.conf
	    echo '# generated by /sbin/dhclient-script' > /etc/yp.conf
	    let contents=0
	    for I in $new_nis_servers; do
		echo "ypserver $I" >> /etc/yp.conf
		let contents=contents+1
	    done
	    level=`/sbin/runlevel`
	    level=${level##*\ }
	    if [ "$level" = "unknown" ]; then
		level=1;
	    fi
	    if [ $contents -gt 0 ] && [[ "$level" = [0-6] ]] && /sbin/chkconfig --level=$level ypbind >/dev/null 2>&1 && [ -r /var/run/ypbind.pid ] && yppid=`cat /var/run/ypbind.pid` && [ -d /proc/${yppid} ] && [ "`if [ -x /sbin/busybox ]; then /sbin/busybox readlink /proc/${yppid}/exe; else echo /sbin/ypbind; fi`" = "/sbin/ypbind" ] ; then
	       kill -HUP $yppid;
	    fi
	fi
    fi
    if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 16 ) != 16 )); then
	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
		    /bin/mv -f /etc/localtime /etc/localtime.predhclient;
		    /bin/cp -fp $tzfile /etc/localtime;
		    /bin/touch /etc/localtime;
		fi;
	    fi;
	fi;
	if [ "${PEERNTP}" = no ]; then
	    :
	elif [ -n "$new_ntp_servers" ] && [ -e /etc/ntp.conf ]; then
	    save_previous /etc/ntp.conf
	    /bin/egrep -v '^server .*  # added by /sbin/dhclient-script$'< /etc/ntp.conf.predhclient > /etc/ntp.conf
	    for s in $new_ntp_servers; do
	      echo "server $s  # added by /sbin/dhclient-script" >> /etc/ntp.conf;
	    done
	    if [ -x /usr/bin/diff ] && /usr/bin/diff -q /etc/ntp.conf /etc/ntp.conf.predhclient >/dev/null 2>&1; then
		: ;
	    else
		/sbin/service ntpd condrestart >/dev/null 2>&1
	    fi;
	fi
    fi;
}

if [ x$new_broadcast_address != x ] && [ x$new_subnet_mask != x ] && [ "$new_subnet_mask" != "255.255.255.255" ]; then
  new_broadcast_arg="broadcast $new_broadcast_address"
fi
if [ x$old_broadcast_address != x ]; then
  old_broadcast_arg="broadcast $old_broadcast_address"
fi
if [ x$new_subnet_mask != x ]; then
  new_subnet_arg="netmask $new_subnet_mask"
fi
if [ x$old_subnet_mask != x ]; then
  old_subnet_arg="netmask $old_subnet_mask"
fi
if [ x$alias_subnet_mask != x ]; then
  alias_subnet_arg="netmask $alias_subnet_mask"
fi

if [ x$reason = xMEDIUM ]; then
  # Linux doesn't do mediums (ok, ok, media).
  exit_with_hooks 0
fi

added_old_broadcast_route=0;
if [ x$reason = xPREINIT ]; then
    if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 2 ) != 2 )); then
	if [ x$alias_ip_address != x ]; then
    # Bring down alias interface. Its routes will disappear too.
	    ifconfig $interface:0- inet 0
	fi
	if [ x$keep_old_ip = xyes ]; then
	    ifconfig $interface up
	elif [ $relmajor -lt 2 ] || ( [ $relmajor -eq 2 ] && [ $relminor -eq 0 ] )   then
	    ifconfig $interface inet 0.0.0.0 netmask 0.0.0.0 \
		broadcast 255.255.255.255 up
    # Add route to make broadcast work. Do not omit netmask.
	    /sbin/ip route replace default dev $interface && added_old_broadcast_route=1;
	else
	    ifconfig $interface 0 up
	fi     

  # We need to give the kernel some time to get the interface up.
  #	sleep 1
  # I don't think this is necessary with modern kernels - no problems found during testing -
  # JVD, 2005-06-17
	# but just in case:
	if [ -n "$DHCLIENT_DELAY" ] && [ "$DHCLIENT_DELAY" -gt 0 ] ; then
	    sleep $DHCLIENT_DELAY;
	fi;
	exit_with_hooks 0
    fi;
fi

if [ x$reason = xARPCHECK ] || [ x$reason = xARPSEND ]; then
    if [ -z "$new_ip_address" ] || [ -z "$interface" ] ||  /sbin/arping -q -f -c 2 -w 3 -D -I ${interface} ${new_ip_address}; then
	exit_with_hooks 0
    else
	exit_with_hooks 1
    fi;
fi
  
if [ x$reason = xBOUND ] || [ x$reason = xRENEW ] || \
   [ x$reason = xREBIND ] || [ x$reason = xREBOOT ]; then    
    dhconfig ;
    exit_with_hooks 0
fi

if [ x$reason = xEXPIRE ] || [ x$reason = xFAIL ] || [ x$reason = xRELEASE ] \
   || [ x$reason = xSTOP ]; then
  if [ -f /etc/resolv.conf.predhclient ]; then
     change_resolv_conf /etc/resolv.conf.predhclient
     rm -f /etc/resolv.conf.predhclient
  fi
  if [ -n "$DHCP_TIME_OFFSET_SETS_TIMEZONE" ] && [[ "$DHCP_TIME_OFFSET_SETS_TIMEZONE" = [yY1]* ]]; then
      if [ -e /etc/localtime.predhclient ]; then
	  /bin/rm -f /etc/localtime
	  /bin/mv -f /etc/localtime.predhclient /etc/localtime;
	  /bin/touch /etc/localtime;
      fi;
  fi;
  if [ -f /etc/ntp.conf.predhclient ]; then
     /bin/rm -f /etc/ntp.conf
     /bin/mv -f /etc/ntp.conf.predhclient /etc/ntp.conf
     service ntpd condrestart >/dev/null 2>&1 
  fi
  if [ -f /etc/yp.conf.predhclient ]; then
     /bin/rm -f /etc/yp.conf
     /bin/mv -f /etc/yp.conf.predhclient /etc/yp.conf
     level=`/sbin/runlevel`
     level=${level##*\ }
     if [ "$level" = "unknown" ]; then
	 level=1;
     fi
     if [[ "$level" = [0-6] ]] && /sbin/chkconfig --level=$level ypbind >/dev/null 2>&1 && [ -r /var/run/ypbind.pid ] && yppid=`cat /var/run/ypbind.pid` && [ -d /proc/${yppid} ] && [ "`if [ -x /sbin/busybox ]; then /sbin/busybox readlink /proc/${yppid}/exe; else echo /sbin/ypbind; fi`" = "/sbin/ypbind" ] ; then
	 kill -HUP $yppid;
     fi
  fi 
  if [ -x /etc/dhclient-${interface}-down-hooks ]; then
      . /etc/dhclient-${interface}-down-hooks;
  elif [ -x /etc/dhclient-down-hooks ]; then
      . /etc/dhclient-down-hooks;
  fi;
  if [ x$alias_ip_address != x ]; then
    # Turn off alias interface.
    ifconfig $interface:0- inet 0
  fi
  if [ x$old_ip_address != x ]; then
    # Shut down interface, which will delete routes and clear arp cache.
    ifconfig $interface inet 0 down
  fi
  if [ x$alias_ip_address != x ]; then
    ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
    /sbin/ip route replace ${alias_ip_address}/32 $interface:0
  fi
  exit_with_hooks 0
fi

if [ x$reason = xTIMEOUT ] && [ "x$new_routers" != 'x' ]; then
    if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 2 ) != 2 )); then
	if [ x$alias_ip_address != x ]; then
	    ifconfig $interface:0- inet 0
	fi
	ifconfig $interface inet $new_ip_address $new_subnet_arg \
					$new_broadcast_arg
    fi;
    set $new_routers
    if ping -q -c 1 -w 10 -I $interface $1; then
	dhconfig ;
	exit_with_hooks 0
    fi
    if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 2 ) != 2 )); then
	ifconfig $interface inet 0 down
    fi;
    exit_with_hooks 1
elif [ x$reason = xTIMEOUT ]; then
  exit_with_hooks 1
fi
exit_with_hooks 0