#!/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.

# 'ip' just looks too weird.  /sbin/ip looks less weird.
ip=/sbin/ip

make_resolv_conf() {
  if [ x"$new_domain_name_servers" != x ]; then
    cat /dev/null > /etc/resolv.conf.dhclient
    chmod 644 /etc/resolv.conf.dhclient
    if [ x"$new_domain_search" != x ]; then
      echo search $new_domain_search >> /etc/resolv.conf.dhclient
    elif [ x"$new_domain_name" != x ]; 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 >> /etc/resolv.conf.dhclient
    fi
    for nameserver in $new_domain_name_servers; do
      echo nameserver $nameserver >>/etc/resolv.conf.dhclient
    done

    mv /etc/resolv.conf.dhclient /etc/resolv.conf
  elif [ "x${new_dhcp6_name_servers}" != x ] ; then
    cat /dev/null > /etc/resolv.conf.dhclient6
    chmod 644 /etc/resolv.conf.dhclient6

    if [ "x${new_dhcp6_domain_search}" != x ] ; then
      echo search ${new_dhcp6_domain_search} >> /etc/resolv.conf.dhclient6
    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 >> /etc/resolv.conf.dhclient6
    done
    shopt -u nocasematch 

    mv /etc/resolv.conf.dhclient6 /etc/resolv.conf
  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

###
### DHCPv4 Handlers
###

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 $alias_subnet_mask"
fi
if [ x$new_interface_mtu != x ]; then
  mtu_arg="mtu $new_interface_mtu"
fi
if [ x$IF_METRIC != x ]; then
  metric_arg="metric $IF_METRIC"
fi

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

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

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

  exit_with_hooks 0
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
  current_hostname=`hostname`
  if [ x$current_hostname = x ] || \
     [ x$current_hostname = "x(none)" ] || \
     [ x$current_hostname = xlocalhost ] || \
     [ x$current_hostname = x$old_host_name ]; then
    if [ x$new_host_name != x$old_host_name ]; then
      hostname "$new_host_name"
    fi
  fi
    
  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
  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 $mtu_arg
    # Add a network route to the computed network address.
    for router in $new_routers; do
      if [ "x$new_subnet_mask" = "x255.255.255.255" ] ; then
	route add -host $router dev $interface
      fi
      route add default gw $router $metric_arg dev $interface
    done
  else
    # we haven't changed the address, have we changed other options           
    # that we wish to update?
    if [ x$new_routers != x ] && [ x$new_routers != x$old_routers ] ; then
      # if we've changed routers delete the old and add the new.
      for router in $old_routers; do
        route del default gw $router
      done
      for router in $new_routers; do
        if [ "x$new_subnet_mask" = "x255.255.255.255" ] ; then
	  route add -host $router dev $interface
	fi
	route add default gw $router $metric_arg dev $interface
      done
    fi
  fi
  if [ x$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
  make_resolv_conf
  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 $mtu_arg
  set $new_routers
  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
    for router in $new_routers; do
      if [ "x$new_subnet_mask" = "x255.255.255.255" ] ; then
	route add -host $router dev $interface
      fi
      route add default gw $router $metric_arg dev $interface
    done
    make_resolv_conf
    exit_with_hooks 0
  fi
  ifconfig $interface inet 0 down
  exit_with_hooks 1
fi

###
### DHCPv6 Handlers
###

if [ x$reason = xPREINIT6 ] ; then
  # Ensure interface is up.
  ${ip} link set ${interface} up

  # Remove any stale addresses from aborted clients.
  ${ip} -f inet6 addr flush dev ${interface} scope global permanent

  exit_with_hooks 0
fi

if [ x${old_ip6_prefix} != x ] || [ x${new_ip6_prefix} != x ] ; then
    echo Prefix ${reason} old=${old_ip6_prefix} new=${new_ip6_prefix}

    exit_with_hooks 0
fi

if [ x$reason = xBOUND6 ] ; then
  if [ x${new_ip6_address} = x ] || [ x${new_ip6_prefixlen} = x ] ; then
    exit_with_hooks 2;
  fi

  ${ip} -f inet6 addr add ${new_ip6_address}/${new_ip6_prefixlen} \
	dev ${interface} scope global

  # Check for nameserver options.
  make_resolv_conf

  exit_with_hooks 0
fi

if [ x$reason = xRENEW6 ] || [ x$reason = xREBIND6 ] ; then
  if [ x${new_ip6_address} = x ] || [ x${new_ip6_prefixlen} = x ] ; then
    exit_with_hooks 2;
  fi

  ${ip} -f inet6 addr add ${new_ip6_address}/${new_ip6_prefixlen} \
	dev ${interface} scope global

  # Make sure nothing has moved around on us.

  # Nameservers/domains/etc.
  if [ "x${new_dhcp6_name_servers}" != "x${old_dhcp6_name_servers}" ] ||
     [ "x${new_dhcp6_domain_search}" != "x${old_dhcp6_domain_search}" ] ; then
    make_resolv_conf
  fi

  exit_with_hooks 0
fi

if [ x$reason = xDEPREF6 ] ; then
  if [ x${new_ip6_prefixlen} = x ] ; then
    exit_with_hooks 2;
  fi

  ${ip} -f inet6 addr change ${new_ip6_address}/${new_ip6_prefixlen} \
       dev ${interface} scope global preferred_lft 0

  exit_with_hooks 0
fi

if [ x$reason = xEXPIRE6 -o x$reason = xRELEASE6 -o x$reason = xSTOP6 ] ; then
  if [ x${old_ip6_address} = x ] || [ x${old_ip6_prefixlen} = x ] ; then
    exit_with_hooks 2;
  fi

  ${ip} -f inet6 addr del ${old_ip6_address}/${old_ip6_prefixlen} \
	dev ${interface}

  exit_with_hooks 0
fi

exit_with_hooks 0