fs/skeleton/sbin/dhclient-script

#!/bin/sh
# 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.
# Conversion to use ip for ipv4 (instead of ifconfig, route) by Peter Marschall
# Extended for 4.2.2, and ip output to /dev/null removed, by Ken Moffat

# 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.

. /etc/utils.sh

ip=ip
wifi_ifc=eth2

log() {
  echo "$@" >&2
}

log_file_contents() {
  local filename="$1"
  while read line; do
    log "$filename: $line"
  done <$filename
}

routable_ifc() {
  [ "$interface" != "$wifi_ifc" ]
}

is_ipv6() {
  endswith "$reason" "6"
}

merge_resolv_conf() {
    # TODO(dgentry) fix uclibc (http://lists.uclibc.org/pipermail/uclibc/2011-June/045440.html)
    # and then also add /tmp/resolv.conf.dhclient6
    local confs=""

    if [ -e "/tmp/resolv.conf.dhclient" ] ; then
        confs="$confs /tmp/resolv.conf.dhclient"
    fi

    if [ -e /tmp/ipv6_dns_ok ] && [ -e "/tmp/resolv.conf.dhclient6" ]; then
        confs="$confs /tmp/resolv.conf.dhclient6"
    fi

    if [ -n "$confs" ] ; then
        atomic /tmp/resolv.conf "$(cat $confs)"
        log_file_contents /tmp/resolv.conf
    fi
}

make_resolv_conf() {
  if [ -n "$new_domain_name_servers" ]; then
    atomic /tmp/resolv.conf.dhclient "$(
      if [ -n "$new_domain_search" ]; then
        echo search $new_domain_search
        log "dns4 search $new_domain_search"
      elif [ -n "$new_domain_name" ]; 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
        log "dns4 search $new_domain_name"
      fi
      for nameserver in $new_domain_name_servers; do
        echo nameserver $nameserver
        log "dns4 nameserver $nameserver"
      done
    )"
    merge_resolv_conf
  elif [ -n "$new_dhcp6_name_servers" ] ; then
    atomic /tmp/resolv.conf.dhclient6 "$(
      if [ -n "$new_dhcp6_domain_search" ]; then
        echo search $new_dhcp6_domain_search
        log "dns6 search $new_dhcp6_domain_search"
      fi
      for nameserver in $new_dhcp6_name_servers; do
        echo nameserver $nameserver
        log "dns6 nameserver $nameserver"
      done
    )"
    merge_resolv_conf
  fi

  if [ ! -f /tmp/dhclient-logs-uploaded ]; then
    upload-logs-now
    atomic /tmp/dhclient-logs-uploaded "done"
  fi
}

make_cwmp_files() {
  if [ -n "$new_cwmp_acs_url" ]; then
    log "cwmp dhcp acs '$new_cwmp_acs_url'"
    if is_ipv6; then
      set-acs dhcp6 "$new_cwmp_acs_url"
    else
      set-acs dhcp "$new_cwmp_acs_url"
    fi
  fi
  if [ -n "$new_cwmp_provisioning_code" ]; then
    atomic /tmp/cwmp/provisioning_code "$new_cwmp_provisioning_code"
    log "cwmp provisioning '$new_cwmp_provisioning_code'"
  fi
  if [ -n "$new_cwmp_retry_minimum_wait_interval" ]; then
    atomic /tmp/cwmp/retry_minimum_wait_interval "$new_cwmp_retry_minimum_wait_interval"
    log "cwmp retry minwait '$new_cwmp_retry_minimum_wait_interval'"
  fi
  if [ -n "$new_cwmp_retry_interval_multiplier" ]; then
    atomic /tmp/cwmp/retry_interval_multiplier "$new_cwmp_retry_interval_multiplier"
    log "cwmp retry mult '$new_cwmp_retry_interval_multiplier'"
  fi
}

make_etc_hosts() {
  atomic /tmp/hosts "$(
    echo "$new_ip_address  $(hostname)"
    echo "127.0.0.1  localhost"
  )"
  log_file_contents /tmp/hosts
}

make_new_ntp_conf_and_restart() {
  atomic /tmp/ntpd.conf \
      "$(cat /etc/ntpd.conf.default /tmp/ntpd4.conf /tmp/ntpd6.conf \
          2>/dev/null)"
  log_file_contents /tmp/ntpd.conf
  restart ntpd
}

write_ntp_conf_new()
{
  fname=$1

  if [ -z "$new_ntp_servers" ]; then
    rm -f "$fname"
    log "no new ntp servers"
    return
  fi

  atomic "$fname" "$(
    for server in $new_ntp_servers; do
      echo "server $server"
    done
  )"
}

# Must be used on exit.   Invokes the local dhcp client exit hooks, if any.
exit_with_hooks() {
  exit_status=$1
  case $reason in
    BOUND|RENEW|REBIND|REBOOT)
      write_ntp_conf_new /tmp/ntpd4.conf
      ;;

    BOUND6|RENEW6|REBIND6|REBOOT6)
      write_ntp_conf_new /tmp/ntpd6.conf
      ;;

    EXPIRE|FAIL|RELEASE|STOP)
      echo "Removing DHCP4 ntp servers on $reason"
      rm -f /tmp/ntpd4.conf
      ;;

    EXPIRE6|FAIL6|RELEASE6|STOP6)
      echo "Removing DHCP6 ntp servers on $reason"
      rm -f /tmp/ntpd6.conf
      ;;
  esac
  make_new_ntp_conf_and_restart
  exit $exit_status
}

###
### 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 $old_broadcast_address"
fi
if [ -n "$new_subnet_mask" ]; then
    new_mask="/$new_subnet_mask"
fi
if [ -n "$alias_subnet_mask" ]; then
    alias_mask="/$alias_subnet_mask"
fi
if [ x$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.
    $ip -4 addr flush dev ${interface} label ${interface}:0
  fi
  $ip link set dev ${interface} 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

  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.
    $ip -4 addr flush dev ${interface} label ${interface}:0
  fi
  if [ x$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.
    $ip -4 addr flush dev ${interface} label ${interface}

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

    $ip -4 addr add ${new_ip_address}${new_mask} ${new_broadcast_arg} \
                dev ${interface} label ${interface} 2>/dev/null
    if [ -n "$new_interface_mtu" ]; then
      # set MTU
      $ip link set dev ${interface} mtu ${new_interface_mtu}
    fi
    # Add a network route to the computed network address.
    if routable_ifc; then
      if [ x$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
          $ip -4 route del via $router
        done
      fi
      for router in $new_routers; do
        if [ "x$new_subnet_mask" = "x255.255.255.255" ] ; then
          $ip -4 route add ${router} dev $interface
        fi
        $ip -4 route add default via ${router} dev ${interface} \
                    ${metric_arg}
      done
    fi
  fi
  if [ x$new_ip_address != x$alias_ip_address ] && [ x$alias_ip_address != x ];
   then
    $ip -4 addr flush dev ${interface} label ${interface}:0
    $ip -4 addr add ${alias_ip_address}${alias_mask} \
        dev ${interface} label ${interface}:0
    $ip -4 route add ${alias_ip_address} dev ${interface}
  fi
  make_resolv_conf
  make_cwmp_files
  make_etc_hosts
  set-acs bounce
  exit_with_hooks 0
fi

if [ x$reason = xFAIL ] || [ x$reason = xRELEASE ] \
   || [ x$reason = xSTOP ]; then
  if [ x$alias_ip_address != x ]; then
    # Turn off alias interface.
    $ip -4 addr flush dev ${interface} label ${interface}:0
  fi
  if [ x$old_ip_address != x ]; then
    # Shut down interface, which will delete routes and clear arp cache.
    $ip -4 addr flush dev ${interface} label ${interface}
  fi
  if [ x$alias_ip_address != x ]; then
    $ip -4 addr add ${alias_ip_address}${alias_network_arg} \
        dev ${interface} label ${interface}:0
    $ip -4 route add ${alias_ip_address} dev ${interface}
  fi
  exit_with_hooks 0
fi

if [ x$reason = xTIMEOUT ]; then
  if [ x$alias_ip_address != x ]; then
    $ip -4 addr flush dev ${interface} label ${interface}:0
  fi
  $ip -4 addr add ${new_ip_address}${new_mask} ${new_broadcast_arg} \
            dev ${interface} label ${interface}
  if [ -n "$new_interface_mtu" ]; then
    # set MTU
    ip link set dev ${interface} mtu ${new_interface_mtu}
  fi
  set $new_routers
  if routable_ifc && ping -q -c 1 $1; then
    if [ x$new_ip_address != x$alias_ip_address ] && \
                        [ x$alias_ip_address != x ]; then
      $ip -4 addr add ${alias_ip_address}${alias_mask} \
            dev ${interface} label ${interface}:0
      $ip -4 route add ${alias_ip_address} dev ${interface}
    fi
    for router in $new_routers; do
      if [ "x$new_subnet_mask" = "x255.255.255.255" ] ; then
        $ip -4 route add ${router} dev $interface
      fi
      $ip -4 route add default via ${router} dev ${interface} \
                    ${metric_arg}
    done
    make_resolv_conf
    make_cwmp_files
    make_etc_hosts
    exit_with_hooks 0
  fi
  $ip -4 addr flush dev ${interface}
  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
  make_cwmp_files
  exit_with_hooks 0
fi

if [ x$reason = xRENEW6 ] || [ x$reason = xREBIND6 ] ; then
  # 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

  if [ "x${new_cwmp_acs_url}" != "x${old_cwmp_acs_url}" ] ||
     [ "x${new_cwmp_provisioning_code}" != "x${old_cwmp_provisioning_code}" ] ||
     [ "x${new_cwmp_retry_minimum_wait_interval}" != "x${old_cwmp_retry_minimum_wait_interval}" ] ||
     [ "x${new_cwmp_retry_interval_multiplier}" != "x${old_cwmp_retry_interval_multiplier}" ] ; then
    make_cwmp_files
  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$reason = xRELEASE6 -o x$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