#!/bin/sh
# vim: set ts=2 sw=2 et:

#
# Copyright (c) 2012, Novell, Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#  * Redistributions of source code must retain the above copyright notice,
#    this list of conditions and the following disclaimer.
#  * Redistributions in binary form must reproduce the above copyright notice,
#    this list of conditions and the following disclaimer in the documentation
#    and/or other materials provided with the distribution.
#  * Neither the name of the <ORGANIZATION> nor the names of its contributors
#    may be used to endorse or promote products derived from this software
#    without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
#
# (Licensed under the simplified BSD license)
#
# Authors: Vincent Untz <vuntz@opensuse.org>
#

NSSWITCH=/etc/nsswitch.conf

function usage() {
  echo "nss-mdns-config [--enable|--disable] [-4|-6] [--no-backup]"
}

ENABLE=0
DISABLE=0
IPv4=0
IPv6=0
IPvALL=0
BACKUP=1

while test $# -gt 0; do
  case "$1" in
    --enable) ENABLE=1; shift;;
    --disable) DISABLE=1; shift;;
    -4) IPv4=1; shift;;
    -6) IPv6=1; shift;;
    --no-backup) BACKUP=0; shift;;
    *) usage; exit 1;;
  esac
done

if test "$ENABLE" -eq 1 -a "$DISABLE" -eq 1; then
  usage
  exit 1
fi

if test "$IPv4" -eq 1 -a "$IPv6" -eq 1; then
  # Supporting -4 and -6 at the same time would make --enable more complex,
  # since we'd like it to add both mdns4_minimal and mdns6_minimal. So just
  # don't do it for now.
  usage
  exit 1
fi

if test "$IPv4" -ne 1 -a "$IPv6" -ne 1; then
  IPv4=1
  IPv6=1
  IPvALL=1
fi

if test ! -f "$NSSWITCH"; then
  if test "$ENABLE" -ne 1 -a "$DISABLE" -ne 1; then
    echo "No $NSSWITCH file."
  fi
  exit 0
fi

HOSTS=$(grep -m1 "^\s*hosts:" "$NSSWITCH")

if test $? -ne 0; then
  echo "No hosts configuration in $NSSWITCH."
  exit 0
fi

VALUE=$(echo $HOSTS | sed "s/^\s*hosts:\s*//g")

if test "$ENABLE" -ne 1 -a "$DISABLE" -ne 1; then

  IPv4_ENABLED=0
  IPv6_ENABLED=0
  ENABLED=0

  for ITEM in $VALUE; do
    if test "$ITEM" == "mdns4_minimal" -o "$ITEM" == "mdns4"; then
      IPv4_ENABLED=1
    elif test "$ITEM" == "mdns6_minimal" -o "$ITEM" == "mdns6"; then
      IPv6_ENABLED=1
    elif test "$ITEM" == "mdns_minimal" -o "$ITEM" == "mdns"; then
      ENABLED=1
    fi
  done

  if test "$ENABLED" -eq 1; then
    echo "Full support for nss-mdns is enabled."
  elif test "$IPv4_ENABLED" -eq 1 -a "$IPv6_ENABLED" -eq 1; then
    echo "Support for nss-mdns is enabled for IPv4 and IPv6."
  elif test "$IPv4_ENABLED" -eq 1; then
    echo "Support for nss-mdns is enabled for IPv4."
  elif test "$IPv6_ENABLED" -eq 1; then
    echo "Support for nss-mdns is enabled for IPv6."
  else
    echo "Support for nss-mdns is disabled."
  fi

elif test "$DISABLE" -eq 1; then

  NEWVALUE=""
  DROPACTION=0

  for ITEM in $VALUE; do
    if test \( "$ITEM" == "mdns4_minimal" -o "$ITEM" == "mdns4" \) -a "$IPv4" -eq 1; then
      DROPACTION=1
    elif test \( "$ITEM" == "mdns6_minimal" -o "$ITEM" == "mdns6" \) -a "$IPv6" -eq 1; then
      DROPACTION=1
    elif test "$ITEM" == "mdns_minimal" -o "$ITEM" == "mdns"; then
      if test "$IPvALL" -eq 1; then
        DROPACTION=1
      elif test "$IPv4" -eq 1; then
        NEWVALUE="$NEWVALUE `echo $ITEM | sed 's:mdns:mdns6:'`"
        DROPACTION=0
      elif test "$IPv6" -eq 1; then
        NEWVALUE="$NEWVALUE `echo $ITEM | sed 's:mdns:mdns4:'`"
        DROPACTION=0
      else
        echo "Internal error when disabling $ITEM."
        exit 1
      fi
    elif test "${ITEM::1}" == "[" -a "$DROPACTION" -eq 1; then
      DROPACTION=0
    else
      NEWVALUE="$NEWVALUE $ITEM"
      DROPACTION=0
    fi
  done

  NEWVALUE=$(echo $NEWVALUE | sed "s/^\s*//;s/^\s*$//")

  if test "$BACKUP" -eq 1; then
    cp -a "$NSSWITCH" "${NSSWITCH}bak"
  fi
  sed -i "s/\(^\s*hosts:\s*\).*/\1$NEWVALUE/" "$NSSWITCH"

elif test "$ENABLE" -eq 1; then

  NEWVALUE=""
  FOUND=0
  FOUND_DNS=0
  DROPACTION=0

  for ITEM in $VALUE; do
    if test \( "$ITEM" == "mdns_minimal" -o "$ITEM" == "mdns4_minimal" -o "$ITEM" == "mdns6_minimal" \); then
      if test "$FOUND_DNS" -eq 1; then
        # don't keep *_minimal after dns; it's not desired there
        DROPACTION=1
      else
        if test "$IPvALL" -eq 1 -a \( "$ITEM" == "mdns4_minimal" -o "$ITEM" == "mdns6_minimal" \); then
          # no need to keep mdns[46]_minimal since we'll add mdns_minimal
          DROPACTION=1
        else
          if test "$ITEM" == "mdns_minimal"; then
            FOUND=1
          elif test "$ITEM" == "mdns4_minimal" -a "$IPv4" -eq 1; then
            FOUND=1
          elif test "$ITEM" == "mdns6_minimal" -a "$IPv6" -eq 1; then
            FOUND=1
          fi
          # force the use of [NOTFOUND=return] after *_minimal
          NEWVALUE="$NEWVALUE $ITEM [NOTFOUND=return]"
          DROPACTION=1
        fi
      fi
    elif test \( "$ITEM" == "mdns" -o "$ITEM" == "mdns4" -o "$ITEM" == "mdns6" \); then
      # we simply don't use the non-minimal version in our setup, so drop it
      DROPACTION=1
    elif test "$ITEM" == "dns"; then
      FOUND_DNS=1
      DROPACTION=0
      if test "$FOUND" -ne 1; then
        FOUND=1
        if test "$IPvALL" -eq 1; then
          NEWVALUE="$NEWVALUE mdns_minimal [NOTFOUND=return] $ITEM"
        elif test "$IPv4" -eq 1; then
          NEWVALUE="$NEWVALUE mdns4_minimal [NOTFOUND=return] $ITEM"
        elif test "$IPv6" -eq 1; then
          NEWVALUE="$NEWVALUE mdns6_minimal [NOTFOUND=return] $ITEM"
        else
          echo "Internal error when enabling."
          exit 1
        fi
      else
        NEWVALUE="$NEWVALUE $ITEM"
      fi
    elif test "${ITEM::1}" == "[" -a "$DROPACTION" -eq 1; then
      DROPACTION=0
    else
      NEWVALUE="$NEWVALUE $ITEM"
      DROPACTION=0
    fi
  done

  if test "$FOUND_DNS" -ne 1; then
    echo "No dns service for hosts configuration in $NSSWITCH."
    exit 0
  fi

  NEWVALUE=$(echo $NEWVALUE | sed "s/^\s*//;s/^\s*$//")

  if test "$BACKUP" -eq 1; then
    cp -a "$NSSWITCH" "${NSSWITCH}bak"
  fi
  sed -i "s/\(^\s*hosts:\s*\).*/\1$NEWVALUE/" "$NSSWITCH"

fi