#!/bin/sh
  
  # dhclient-script from OpenWRT project
  # http://git.openwrt.org/?p=packages.git;a=blob;f=net/isc-dhcp/files/dhclient-script;h=4afebc0ad20ebac51c5baae5ed01c6713e3a0fd0;hb=HEAD
  
  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
  
    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
      for nameserver in ${new_dhcp6_name_servers} ; do
        echo nameserver ${nameserver} >> /etc/resolv.conf.dhclient6
      done
    fi
  
    # if both v4 and v6 clients are running, concatenate results
    cat /etc/resolv.conf.* > /etc/resolv.conf
  }
  
  # 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 $new_broadcast_address"
  fi
  if [ x$new_subnet_mask != x ]; then
    new_subnet_arg="netmask $new_subnet_mask"
  fi
  if [ x$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$reason = xPREINIT ]; then
    if [ x$alias_ip_address != x ]; then
      # Bring down alias interface. Its routes will disappear too.
      ifconfig $interface:0- 0.0.0.0
    fi
    ifconfig $interface 0.0.0.0 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$old_host_name ]; then
      if [ x$current_hostname = x ] || \
         [ 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 $interface:0- 0.0.0.0
    fi
    if [ x$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 0.0.0.0 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 $new_ip_address $new_subnet_arg \
  							$new_broadcast_arg
      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 $router
      done
    fi
    if [ x$new_ip_address != x$alias_ip_address ] && [ x$alias_ip_address != x ];
     then
      ifconfig $interface:0- 0.0.0.0
      ifconfig $interface:0 $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 $interface:0- 0.0.0.0
    fi
    if [ x$old_ip_address != x ]; then
      # Shut down interface, which will delete routes and clear arp cache.
      ifconfig $interface 0.0.0.0 down
    fi
    if [ x$alias_ip_address != x ]; then
      ifconfig $interface:0 $alias_ip_address $alias_subnet_arg
      route add -host $alias_ip_address $interface:0
    fi
  
    # remove v4 dns configuration for this interface
    rm /etc/resolv.conf.dhclient
    cat /etc/resolv.conf.* > /etc/resolv.conf
  
    exit_with_hooks 0
  fi
  
  if [ x$reason = xTIMEOUT ]; then
    if [ x$alias_ip_address != x ]; then
      ifconfig $interface:0- 0.0.0.0
    fi
    ifconfig $interface $new_ip_address $new_subnet_arg \
  					$new_broadcast_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 $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
      done
      make_resolv_conf
      exit_with_hooks 0
    fi
    ifconfig $interface 0.0.0.0 down
    exit_with_hooks 1
  fi
  
  ###
  ### DHCPv6 Handlers
  ###
  
  if [ x$reason = xPREINIT6 ]; then
    # Ensure interface is up.
    ifconfig ${interface} up
  
    # Remove any stale addresses from aborted clients.
    ip -f inet6 addr flush dev ${interface} scope global
  
    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
  
    ifconfig ${interface} add ${new_ip6_address}/${new_ip6_prefixlen}
  
    # Check for nameserver options.
    make_resolv_conf
  
  ### <<
    # Set up softwire tunnel
    if [ x${new_dhcp6_softwire} != x ] ; then
      /etc/init.d/dhclient stop
      ifconfig ${interface} 0.0.0.0
      ip -6 tunnel add tun0 mode ipip6 \
  	remote ${new_dhcp6_softwire} \
  	local ${new_ip6_address} \
  	dev ${interface} encaplimit none
      ip link set tun0 up
      ip route add default dev tun0
    fi
  ### >>
  
    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
  
    ifconfig ${interface} add ${new_ip6_address}/${new_ip6_prefixlen}
  
    # 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_address} = x ] ; then
      exit_with_hooks 2;
    fi
  
    # Busybox ifconfig has no way to communicate this to the kernel, so ignore it
  
    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
  
    ifconfig ${interface} del ${old_ip6_address}/${old_ip6_prefixlen}
  
    # remove v6 dns configuration for this interface
    rm /etc/resolv.conf.dhclient6
    cat /etc/resolv.conf.* > /etc/resolv.conf
  
  ### <<
    # Tear down softwire tunnel
    if [ x${old_dhcp6_softwire} != x ] ; then
      ip link set tun0 down
      ip tunnel del tun0
    fi
  ### >>
  
    exit_with_hooks 0
  fi
  
  exit_with_hooks 0