#!/bin/sh
# dhclient-script for Linux. Dan Halbert, March, 1997.
# 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.

############################################################################
# This horror, which depends on bash, does a bitwise and of the ip
# address and the network mask to produce the network address.
eval `echo $new_ip_address $new_subnet_mask | sed -e 's/\([0-9]\+\).\([0-9]\+\).\([0-9]\+\).\([0-9]\+\) \([0-9]\+\).\([0-9]\+\).\([0-9]\+\).\([0-9]\+\)/new_network_address="$[\1\&\5].$[\2\&\6].$[\3\&\7].$[4\&\8]"/'`

# A similar horror to calculate the broadcast address if it's not given.
if [ x$new_broadcast_address = x ]; then
  eval `echo $new_ip_address $new_subnet_mask | sed -e 's/\([0-9]\+\).\([0-9]\+\).\([0-9]\+\).\([0-9]\+\) \([0-9]\+\).\([0-9]\+\).\([0-9]\+\).\([0-9]\+\)/new_broadcast_address="$[(\1\|~\5)\&255].$[(\2\|~\6)\&255].$[(\3\|~\7)\&255].$[(4\|~\8)\&255]"/'`
fi

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 0
fi

if [ x$reason = xPREINIT ]; then
  if [ x$alias_ip_address != x ]; then
    # Bring down alias interface. Its routes will disappear too.
    ifconfig $interface:0- inet 0
  fi
  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
  exit 0
fi

if [ x$reason = xARPCHECK ] || [ x$reason = xARPSEND ]; then
  exit 0;
fi
  
if [ x$reason = xBOUND ] || [ x$reason = xRENEW ] || \
   [ x$reason = xREBIND ] || [ x$reason = xREBOOT ]; 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 down

  fi
  if [ x$old_ip_address = x ] || [ x$old_ip_address != x$new_ip_address ] || \
     [ x$reason = xBOUND ] || [ x$reason = xREBOOT ]; then

    ifconfig $interface inet $new_ip_address $new_subnet_arg \
					$new_broadcast_arg
    # Add a network route to the computed network address.
    route add -net $new_network_address $new_subnet_arg dev $interface
    for router in $new_routers; do
      route add default gw $router
    done
  fi
  if [ x$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
  echo domain $new_domain_name >/etc/resolv.conf
  for nameserver in $new_domain_name_servers; do
    echo nameserver $nameserver >>/etc/resolv.conf
  done
  exit 0
fi

if [ x$reason = xEXPIRE ] || [ x$reason = xFAIL ]; 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 $interface inet down
  fi
  if [ x$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 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 -w 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
    route add -net $new_network_address
    for router in $new_routers; do
      route add default gw $router
    done
    echo domain $new_domain_name >/etc/resolv.conf.std
    for nameserver in $new_domain_name_servers; do
      echo nameserver $nameserver >>/etc/resolv.conf.std
    done
    if [ -f /etc/resolv.conf ]; then
      rm -f /etc/resolv.conf
      ln /etc/resolv.conf.std /etc/resolv.conf
    fi
    exit 0
  fi
  ifconfig $interface inet down
  exit 1
fi

exit 0