#!/bin/sh
# Start/stop/restart the BIND name server daemon (named).

# Start bind.  In the past it was more secure to run BIND
# as a non-root user (for example, with '-u daemon'), but
# the modern version of BIND knows how to use the kernel's
# capability mechanism to drop all root privileges except
# the ability to bind() to a privileged port and set process
# resource limits, so -u should not be needed.  If you wish
# to use it anyway, chown the /var/run/named directory to
# the non-root user.
#
# IMPORTANT:  With a 2.6 or newer kernel, if "capability"
# was built as a module you may have to load it first:
#
#modprobe capability
#
# You can uncomment a line in /etc/rc.d/rc.modules to do
# this automatically at boot time.  If your kernel requires
# "capability" to run BIND and you don't load it first, this
# script will attempt to cover for you by loading the
# module anyway, but you'll get some big ugly warnings.  ;-)

# You might also consider running BIND in a "chroot jail",
# a discussion of which may be found in
# /usr/doc/Linux-HOWTOs/Chroot-BIND-HOWTO.
#
# One last note:  rndc has a lot of other nice features that
# it is not within the scope of this start/stop/restart script
# to support.  For more details, see "man rndc" or just type
# "rndc" to see the options.


# Sanity check.  If either /usr/sbin/named or /etc/named.conf
# aren't ready, it doesn't make much sense to try to run this
# script:
if [ ! -x /usr/sbin/named ]; then
  echo "/etc/rc.d/rc.bind:  no /usr/sbin/named found (or not executable); cannot start."
  exit 1
elif [ ! -f /etc/named.conf ]; then
  echo "/etc/rc.d/rc.bind:  no /etc/named.conf found; cannot start /usr/sbin/named."
  exit 1
fi

# Start BIND.  As many times as you like.  ;-)
# Seriously, don't run "rc.bind start" if BIND is already
# running or you'll get more than one copy running.
bind_start() {
  if [ -x /usr/sbin/named ]; then
    echo "Starting BIND:  /usr/sbin/named"
    /usr/sbin/named
  fi
  if ! ps axc | grep -q named ; then
    # A common reason why BIND might not start is that the
    # Linux capabilities module is required on Linux 2.6.
    # So, we will warn the user and then load the module.
    # While it's possible to test to see if this is true,
    # that approach could be a moving target, so we'll
    # just go for the brute force approach.  It's likely
    # to be safe enough.
    echo "WARNING:  named did not start.  Perhaps this is because"
    echo "the \"capability\" module required by newer kernels is"
    echo "not loaded (or built into the kernel)?"
    echo "Attempting to load security capability module:"
    echo "/sbin/modprobe capability"
    /sbin/modprobe capability
    echo "Attempting to start named again:  /usr/sbin/named"
    /usr/sbin/named
    if ps axc | grep -q named ; then
      echo "SUCCESS:  named started.  To avoid this warning in"
      echo "the future you can edit your /etc/rc.d/rc.modules"
      echo "to load the \"capability\" module."
    else
      echo "FAILED:  Sorry, but even after attempting to load"
      echo "the \"capability\" module, named did not start."
      echo "There may be a different configuration error that"
      echo "needs fixing.  Good luck!"
    fi
  fi
}

# Stop all running copies of BIND (/usr/sbin/named):
bind_stop() {
  echo "Stopping BIND:  /usr/sbin/rndc stop"
  /usr/sbin/rndc stop
  # A problem with using "/usr/sbin/rndc stop" is that if you
  # managed to get multiple copies of named running it will
  # only stop one of them and then can't stop the others even
  # if you run it again.  So, after doing things the nice way
  # we'll do them the old-fashioned way.  If you don't like
  # it you can comment it out, but unless you have a lot of
  # other programs you run called "named" this is unlikely
  # to have any ill effects:
  sleep 1
  if ps axc | grep -q named ; then
    echo "Using "killall named" on additional BIND processes..."
    /bin/killall named 2> /dev/null
  fi
}

# Reload BIND:
bind_reload() {
  /usr/sbin/rndc reload
}

# Restart BIND:
bind_restart() {
  bind_stop
  bind_start
}

# Get BIND status:
bind_status() {
  /usr/sbin/rndc status
}

case "$1" in
'start')
  bind_start
  ;;
'stop')
  bind_stop
  ;;
'reload')
  bind_reload
  ;;
'restart')
  bind_restart
  ;;
'status')
  bind_status
  ;;
*)
  echo "usage $0 start|stop|reload|restart|status"
esac