#!/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.

# 4. TIMEOUT not tested. ping has a flag I don't know, and I'm suspicious
# of the $1 in its args.


# Debugging:
#
# logs entire run of dhclient-script to /var/log/dhclient-script, 
# if DHCLIENT_DEBUG is set in sysconfig/network/dhcp
#
eval `grep "^DHCLIENT_DEBUG=" /etc/sysconfig/network/dhcp`
if [ "$DHCLIENT_DEBUG" = yes ]; then
  set -a # allexport
  (
    echo '****************' 
    echo "$0 $*"
    date
    echo '----------------'
    set
    echo '----------------'
  ) >> /var/log/dhclient-script
  exec 2>> /var/log/dhclient-script
  set +a
  set -x
fi

if [ -n "${dhc_dbus}" ]; then
   /usr/bin/dbus-send \
       --system \
       --dest=com.redhat.dhcp \
       --type=method_call \
       /com/redhat/dhcp/$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;


make_resolv_conf() {
  # first, look if we are allowed to modify resolv.conf:
  eval `grep "^MODIFY_RESOLV_CONF_DYNAMICALLY=" /etc/sysconfig/network/config`
  eval `grep "^DHCLIENT_MODIFY_RESOLV_CONF=" /etc/sysconfig/network/dhcp`

  test "$MODIFY_RESOLV_CONF_DYNAMICALLY" = no \
    -o "$DHCLIENT_MODIFY_RESOLV_CONF" = no \
    && return 

  # It might be useful to have more than one domain in the searchlist. To
  # achieve this set DHCLIENT_KEEP_SEARCHLIST in /etc/sysconfig/network/dhcp to "yes"
  # and put the additional domains in the searchlist of the *unmodified*
  # /etc/resolv.conf. When the client is configured via DHCP the old
  # searchlist will be appended to the new one.
  oldsearchlist=""
  eval `grep "^DHCLIENT_KEEP_SEARCHLIST=" /etc/sysconfig/network/dhcp`
  if test "$DHCLIENT_KEEP_SEARCHLIST" = yes ; then
    oldsearchlist=`while read line; do 
			case $line in search*) oldsearchlist=${line/search /};; esac; 
		done< /etc/resolv.conf; 
		echo -n $oldsearchlist` 
  fi



  # now, backup the existing resolv.conf first. BUT:
  # an old backup copy should not be there, because the init script deletes them; if there 
  # is one, it must be current and we don't want to overwrite it
  # (since this script is called by dhclient more than once)
  if ! test -f /etc/resolv.conf.saved.by.dhclient ; then
    mv /etc/resolv.conf /etc/resolv.conf.saved.by.dhclient &> /dev/null
  fi

  # put a comment into the new file
  # FIXME: in theory we should use /sbin/modify_resolvconf for the modifications
  # instead of fiddling around with it ourselves. 
  write_informational_resolv_conf_header

  echo search $new_domain_name $oldsearchlist >>/etc/resolv.conf
  chmod 644 /etc/resolv.conf
  for nameserver in $new_domain_name_servers; do
    echo nameserver $nameserver >>/etc/resolv.conf
  done
}

function write_informational_resolv_conf_header() {
  cat > /etc/resolv.conf << EOF
### BEGIN INFO
#
# Modified_by:  dhclient
# Backup:       /etc/resolv.conf.saved.by.dhclient
# Process:      /sbin/dhclient
# Process_id:   $(pidof dhclient)
# Script:       /sbin/dhclient-script
#
# Info:         This is a temporary resolv.conf created by dhclient.
#               A previous resolv.conf has been saved as
#               /etc/resolv.conf.saved.by.dhclient and will be
#               restored when dhclient is stopped.
#
#               If you don't like dhclient to change your nameserver 
#               settings, set DHCLIENT_MODIFY_RESOLV_CONF in 
#               /etc/sysconfig/network/dhcp to "no", or set 
#               MODIFY_RESOLV_CONF_DYNAMICALLY in /etc/sysconfig/network/config 
#               to "no". 
#               You can also customize /etc/dhclient.conf (man 5 dhclient.conf)
#               using the supersede and/or prepend option.
### END INFO

EOF

# Make sure that the file is world readable even if umask is set to e.g. 077 

}

# 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

release=`uname -r`
release=`expr $release : '\(.*\)\..*'`
relminor=`echo $release |sed -e 's/[0-9]*\.\([0-9][0-9]*\)\(\..*\)*$/\1/'`
relmajor=`echo $release |sed -e 's/\([0-9][0-9]*\)\..*$/\1/'`

if [ x$new_broadcast_address != x ]; 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

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 [ $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.
      route add default dev $interface netmask 0.0.0.0
    else
      ifconfig $interface 0 up
    fi

    # We need to give the kernel some time to get the interface up.
    sleep 1

    exit_with_hooks 0
  fi
fi

if [ x$reason = xARPCHECK ] || [ x$reason = xARPSEND ]; then
  exit_with_hooks 0
fi
  
if [ x$reason = xBOUND ] || [ x$reason = xRENEW ] || \
   [ x$reason = xREBIND ] || [ x$reason = xREBOOT ]; then
  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$old_ip_address = x ] || [ x$old_ip_address != x$new_ip_address ] || \
     [ x$reason = xBOUND ] || [ x$reason = xREBOOT ]; then

    if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 2 ) != 2 )); then
      ifconfig $interface inet $new_ip_address $new_subnet_arg \
							$new_broadcast_arg
    fi
    if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 4 ) != 4 )); then
      # Add a network route to the computed network address.
      if [ $relmajor -lt 2 ] || \
		( [ $relmajor -eq 2 ] && [ $relminor -eq 0 ] ); then
        route add -net $new_network_number $new_subnet_arg dev $interface
      fi
      for router in $new_routers; do
        route add default gw $router
      done
    fi
  fi
  if [ -z "${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
      route add -host $alias_ip_address $interface:0
    fi
  fi
  if [ -z "${dhc_dbus}" ] || (( ( dhc_dbus & 1 ) != 1 )); then
    make_resolv_conf
    eval `grep --no-filename "^DHCLIENT_SET_HOSTNAME=" /etc/sysconfig/network/dhcp`
    if [ "$DHCLIENT_SET_HOSTNAME" = yes ] ; then

      current_hostname=`hostname`
      if [ x$current_hostname = x ] || \
         [ x$current_hostname != x$new_host_name ]; then

          if [ x$new_host_name != x ]; then
            hostname $new_host_name
          else
            if [ -x /usr/bin/host ] ; then
              hostname `host "$new_ip_address" | sed 's:^.* ::; s:\..*::'`
            fi
          fi

      fi

    fi
  fi
  exit_with_hooks 0
fi

if [ x$reason = xEXPIRE ] || [ x$reason = xFAIL ] || [ x$reason = xRELEASE ] \
   || [ x$reason = xSTOP ]; then
  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
    route add -host $alias_ip_address $interface:0
  fi
  exit_with_hooks 0
fi

if [ x$reason = xTIMEOUT ]; then
  if [ x$alias_ip_address != x ]; then
    ifconfig $interface:0- inet 0
  fi
  ifconfig $interface inet $new_ip_address $new_subnet_arg \
					$new_broadcast_arg
  set $new_routers
  ############## what is -w in ping?
  if ping -q -c 1 $1; then
    if [ x$new_ip_address != x$alias_ip_address ] && \
			[ x$alias_ip_address != x ]; then
      ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
      route add -host $alias_ip_address dev $interface:0
    fi
    if [ $relmajor -lt 2 ] || \
		( [ $relmajor -eq 2 ] && [ $relminor -eq 0 ] ); then
      route add -net $new_network_number
    fi
    for router in $new_routers; do
      route add default gw $router
    done
    make_resolv_conf
    exit_with_hooks 0
  fi
  ifconfig $interface inet 0 down
  exit_with_hooks 1
fi

# restore backup copy of resolv.conf
if test -f /etc/resolv.conf.saved.by.dhclient ; then
  mv /etc/resolv.conf.saved.by.dhclient /etc/resolv.conf
fi

exit_with_hooks 0
