#!/bin/bash
#
# Copyright (c) 2008 SUSE LINUX Products GmbH, Nuernberg, Germany.
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program.  If not, see <http://www.gnu.org/licenses/>.
#
# Author: Michael Calmer <mc@suse.de>
#         Sven Schober <sschober@suse.de>
#         Marius Tomaschewski <mt@suse.de>
#
##

unset POSIXLY_CORRECT ; set +o posix # we're using non-posix bash features

if test "$UID" != "0" -a "$USER" != root -a -z "$ROOT" ; then
    echo "You must be root to start $0." >&2
    exit 1
fi

# The environment variable ROOT indicates the root of the system to be
# managed by SuSEconfig when that root is not '/'
r="$ROOT"

. "$r/etc/sysconfig/network/scripts/functions.netconfig"

PROGNAME="${0##*/}"
STATEDIR="$r/var/run/netconfig"
debug "$PROGNAME Module called"

. "$r/etc/sysconfig/network/config"

unset DNS_SERVERS ${!DNS_SERVERS_*}

DESTFILE="$r/var/run/dnsmasq-forwarders.conf"
TMP_FILE=""

# *********************
# FUNCTIONS 
# *********************

function write_dnsmasq_forwarders ()
{
    test -z "$1" && return 1

    debug "write_dnsmasq_forwarders: $1 "

    local NAMESERVER=()

    # DESTFILE may be a symlink on a read only /-fs
    DST_FILE=`read_symlink "${DESTFILE}"`
    TMP_FILE=`mktemp "${DST_FILE}.XXXXXX" 2>/dev/null || \
              mktemp -t "${DST_FILE##*/}.XXXXXX"` || return 1

    if test ! -s "$DST_FILE" ; then
        touch "$DST_FILE" ; chmod 644 "$DST_FILE"
    fi

    # * copy dest => tmp to get the file attributes
    # * remove the content 
    # * print a warning on top of this file
    #cp -p "$DST_FILE" "$TMP_FILE"

    # set explicit mode on tmp file instead to preserve the
    # mode of original file that can be wrong (bnc#428458)
    chmod 644 "$TMP_FILE"

    cat << EOT > "$TMP_FILE"
### $DESTFILE file autogenerated by netconfig!
#
# Before you change this file manually, consider to define the
# static DNS configuration using the following variables in the
# /etc/sysconfig/network/config file:
#     NETCONFIG_DNS_STATIC_SEARCHLIST
#     NETCONFIG_DNS_STATIC_SERVERS
#     NETCONFIG_DNS_FORWARDER
# or disable DNS configuration updates via netconfig by setting:
#     NETCONFIG_DNS_POLICY=''
#
# See also the netconfig(8) manual page and other documentation.
#
# Note: Manual change of this file disables netconfig too, but
# may get lost when this file contains comments or empty lines
# only, the netconfig settings are same with settings in this
# file and in case of a "netconfig update -f" call.
#
### Please remove (at least) this line when you modify the file!
EOT

    for ns in $1; do
        # skip duplicates
        for os in ${NAMESERVER[@]} ; do
            [ "x$ns" == "x$os" ] && continue 2
        done

        # resolv.conf supports up to 3 nameserver,
        # but AFAIK not for dnsmasq  ...
        #[ ${#NAMESERVER[@]} -lt 3 ] || break

        NAMESERVER=(${NAMESERVER[@]} ${ns})
    done

    if [ ${#NAMESERVER[@]} -gt 0 ]; then
        {
            for ns in ${NAMESERVER[@]}; do
                echo "nameserver ${ns}"
            done
        } >> "$TMP_FILE"
    fi

    netconfig_check_md5_and_move "$TMP_FILE" "$DESTFILE" ".netconfig" TMP_FILE
    return $?
}

function get_dns_settings()
{
    local cfg=$1 ; shift
    test "x$cfg" = x && return 1
    local SERVICE DNSSERVERS
    local var idx DNS_SERVERS
    debug "exec get_dns_settings: $cfg"

    get_variable "SERVICE" "$cfg"
    idx=`get_ranking_idx "$SERVICE" "$@"`
    debug "     get_dns_settings: service '$SERVICE' => rank '$idx'"

    var="DNS_SERVERS_$idx"
    DNS_SERVERS=(${!var})
    get_variable "DNSSERVERS" "$cfg"
    if [ "x$DNSSERVERS" != "x" ]; then
        DNS_SERVERS=(${DNS_SERVERS[@]} $DNSSERVERS)
    fi
    unset DNSSERVERS
    eval "${var}='${DNS_SERVERS[@]}'"
    debug "     get_dns_settings: ${var}='${!var}'"

    debug "exit get_dns_settings: $cfg"
    return 0
}

function manage_interfaceconfig()
{
    local cfg dir="$1" ; shift
    test "x$dir" != x -a -d "$dir" || return 1

    debug "exec manage_interfaceconfig: $dir"
    for cfg in `ls -X -r "$dir/" 2>/dev/null`; do
        get_dns_settings "$dir/$cfg" "$@"
    done
    debug "exit manage_interfaceconfig: $dir"
    return 0
}

# *********************
# EXECUTION STARTS HERE
# *********************

if [ "$NETCONFIG_DNS_FORWARDER" != "dnsmasq" ]; then
    exit 0;
fi

# just for the case we need the original value...
_NETCONFIG_DNS_RANKING="$NETCONFIG_DNS_RANKING"
case "$_NETCONFIG_DNS_RANKING" in
  auto) _NETCONFIG_DNS_RANKING="$NETCONFIG_DNS_RANKING_DEFAULT" ;;
  none) _NETCONFIG_DNS_RANKING=""                               ;;
esac

# just for the case we need the original value...
_NETCONFIG_DNS_POLICY=`netconfig_policy "$NETCONFIG_DNS_POLICY"`
if [ "x$_NETCONFIG_DNS_POLICY" = "x" ]; then
    #
    # empty policy means do not touch anything. 
    # successful exit.
    #
    exit 0;
fi


sf=0
_g=1
# disable filename glob expansion if needed
shopt -o -q noglob || _g=0
[ $_g ] && shopt -o -s noglob
for POL in $_NETCONFIG_DNS_POLICY; do 
    shopt -o -u noglob
    case "$POL" in
    (NetworkManager)
        debug "Use NetworkManager policy merged settings"
        cfg="$STATEDIR/NetworkManager.netconfig"
        if [ -r "$cfg" ] ; then
            get_dns_settings "$cfg" "$_NETCONFIG_DNS_RANKING"
        fi
        break
    ;;
    (STATIC)
        debug "Keep Static"
        DNS_SERVERS_1="$DNS_SERVERS_1 $NETCONFIG_DNS_STATIC_SERVERS"
    ;;
    (STATIC_FALLBACK)
        debug "Static Fallback"
        sf=1
    ;;
    (*)
        debug "Other: $POL"
        for IFDIR in $STATEDIR/$POL; do
            test -d "$IFDIR" -a \
                 -d "/sys/class/net/${IFDIR##*/}" || continue
            # proceed every interface we find with this match
            manage_interfaceconfig  "$IFDIR" "$_NETCONFIG_DNS_RANKING"
        done
    ;;
    esac
done
[ $_g ] && shopt -o -u noglob

if [ $sf -eq 1 -a -z "$DNS_SERVERS_0" \
               -a -z "$DNS_SERVERS_1" ]; then
    DNS_SERVERS_2="$DNS_SERVERS_2 $NETCONFIG_DNS_STATIC_SERVERS"
fi

# filter out loopback addresses and all own IPs that would case a loop
own_ips=(`ip addr show 2>/dev/null | \
LANG=C LC_ALL=C gawk '/[ ]+(inet|inet6)[ ]+/ { sub("/.*","",$2); print $2; }' 2>/dev/null`)
for idx in 0 1 2 ; do
    var="DNS_SERVERS_$idx"
    val=(${!var})
    new=()
    for ns in ${val[@]} ; do
        case $ns in
            127.*|::1)      ;;
            *)
                for ip in "${own_ips[@]}" ; do
                    test "x$ip" = "x"    && continue
                    test "x$ip" = "x$ns" && continue 2
                done
                new+=("$ns")
            ;;
        esac
    done
    eval "${var}='${new[@]}'"
done

write_dnsmasq_forwarders "$DNS_SERVERS_0 $DNS_SERVERS_1 $DNS_SERVERS_2"
RET=$?

if [ $RET -eq 1 ]; then
    # nothing changed; we are finished
    exit 0
elif [ $RET -eq 2 ]; then
   # user modified the config. Copy aborted
    echo "ATTENTION: You have modified $DESTFILE.  Leaving it untouched..."
    echo "You can find my version in $TMP_FILE ..."
    exit 20
fi

# here we should restart services if needed
# => not needed, dnsmasq polls and reloads itself

exit 0;

# vim: set ts=8 sts=4 sw=4 ai et: