# /etc/dhcp3/dhclient-exit-hooks.d/pointopoint
# set interface in point to point mode if its network mask is 255.255.255.255
# it has only been tested in conditions where the interface was peered with the default
# router and where the address returned by the dhcp server didn't change over time

RUN="yes"

if [ "$RUN" = "yes" ]
then

  # clean old peer config
  if [ "$reason" = "RENEW" -o "$reason" = "REBIND" -o "$reason" = "EXPIRE" ]
  then
    if [ -n "$old_ip_address" -a -n "$old_routers" -a "$old_subnet_mask" = "255.255.255.255" ]
    then
      if [ "$old_ip_address" != "new_ip_address" ]
      then
        set -- $old_routers
        first_router=$1
        ip -4 route del to default via "$first_router"
        ip -4 addr del "$old_ip_address" peer "$first_router/32" dev "$interface"
      fi
    fi
  fi

  # setup new peer config
  if [ "$reason" = "BOUND" -o "$reason" = "RENEW" -o "$reason" = "REBOOT" -o "$reason" = "REBIND" ]
  then
    if [ -n "$new_ip_address" -a -n "$new_routers" -a "$new_subnet_mask" = "255.255.255.255" ]
    then
      set -- $new_routers
      first_router=$1
      ip -4 addr del "$new_ip_address/32" dev "$interface"
      ip -4 addr replace "$new_ip_address" peer "$first_router/32" dev "$interface"
      # silly, "sleep" below is required for next "ip route" to be effective
      sleep 2
      ip -4 route replace to default via "$first_router"
    fi
  fi

fi