#! /bin/sh

# $Id: 0dns-down,v 1.2 2004/07/31 20:49:04 john Exp $

# 0dns-down by John Hasler 1999-2004
# Any possessor of a copy of this program may treat it as if it
# were in the public domain.  I waive all rights.

# Rev. Apr 12 2004 to use resolvconf if installed.

# 0dns-down takes down what 0dns-up sets up.

# If pppconfig has been removed we are not supposed to do anything.
test -f /usr/sbin/pppconfig || exit 0

# Strip options.
PROVIDER=`echo "$PPP_IPPARAM" | cut -d' ' -f1`

ETC="/etc"
RUNDIR="/var/run/pppconfig"
RESOLVCONF="$ETC/resolv.conf"
RESOLVBAK="$RUNDIR/resolv.conf.bak.$PROVIDER"
TEMPRESOLV="$RUNDIR/0dns.$PROVIDER"
PPPRESOLV="$ETC/ppp/resolv"

if [ -x /sbin/resolvconf ]; then
	[ "$1" = "0dns-clean" ] && exit 0
	test -n "$PPP_IFACE" || exit 1
	/sbin/resolvconf -d "${PPP_IFACE}.pppconfig"
fi

umask 022
cd "$RUNDIR" || exit 1

# Are we being called by dns-clean?  If so fix up /etc/resolv.conf
# and clean out /var/run/pppconfig.

if [ "$1" = "0dns-clean" ]
    then 
    # Get the name of the provider active when we went down.  Assume there was only one.
    PROVIDER=`ls -t resolv.conf.bak.* 2>/dev/null | awk 'BEGIN {FS = "." } /resolv\.conf\.bak/ {print $NF} {exit}'`
    # If we don't have a provider we have nothing to do.
    if [ -n "$PROVIDER " ]
	then
	RESOLVBAK="$RUNDIR/resolv.conf.bak.$PROVIDER"
	[ -s "$RESOLVBAK" ] && /bin/cp -Lp "$RESOLVBAK" "$RESOLVCONF"
    fi
    exit 0
fi

# If we don't have a provider we have nothing to do.
[ -z "$PROVIDER" ] && exit 0

# Is PROVIDER something we can use?

test -f "$PPPRESOLV/$PROVIDER" || exit 0

# It is not an error for RESOLVBAK not to exist.

if [ ! -f "$RESOLVBAK" ]
    then
    rm -f "$TEMPRESOLV"
    exit 0
fi

# Make sure that the resolv.conf that 0dns-up installed has not been
# altered.  If has give up.

if [ `stat -c %Y "$TEMPRESOLV"` -ne `stat -c %Y "$RESOLVCONF"` ]
then
    rm -f "$TEMPRESOLV" "$RESOLVBAK"
    exit 0
fi

# Restore resolv.conf.  Follow symlinks.

/bin/cp -Lp "$RESOLVBAK" "$RESOLVCONF" || exit 1
rm -f "$RESOLVBAK" "$TEMPRESOLV"

# Tell nscd about what we've done.

# Restart nscd because resolv.conf has changed
[ -x /etc/init.d/nscd ] && { invoke-rc.d nscd restart || true ; }