#! /bin/sh

#
# mass update TTLs in a list of source files
#

usage() {
    cat <<EOF
Usage: $0 <ttl> <zonefile> ...

Changes the global \$TTL and SOA TTL directly in a list of BIND zone
files specially formatted.

EOF
}

if [ $# -lt 2 ]; then
    usage
    exit
fi

NEW_TTL=$1; shift

# external command dependencies
awk=awk
mv=mv
cut=cut
sed=sed
echo=echo
date=date
printf=printf
mktemp=mktemp

# increment a serial number in a zone file
#
# we assume that the serial line contains the "serial string", eg.:
#                 2005012703      ; serial
#
# from AlternC do_domaines.sh
#
# returns 1 if file isn't readable
# returns 2 if we can't find the serial number
# returns 3 if a tempfile can't be created
increment_serial() {
    if [ -f "$1" ]; then
        # the assumption is here
        SERIAL=`$awk '/^..*serial/ {print $1}' < $1` || return 2
        if [ ! -z "${SERIAL}" ]; then
            DATE=`$echo $SERIAL | $cut -c1-8`
            ORDRE=`$echo $SERIAL | $sed s/"${DATE}0\?"/""/g`
            DATE_JOUR=`$date +%Y%m%d`
            # increment the serial number only if the date hasn't changed
            if [ "X$DATE" = "X$DATE_JOUR" ] ; then
                ORDRE=$(($ORDRE+1))
            else
                ORDRE=1
                DATE=$DATE_JOUR
            fi
            NEW_SERIAL=$DATE`$printf "%.2d" $ORDRE`
            TMPFILE=`$mktemp $1.XXXXXX` || return 3
            # put the serial number in place
            $awk -v NEW_SERIAL=$NEW_SERIAL '{if ($3 =="serial") print "		"NEW_SERIAL "	; serial"; else print $0}' < $1 > $TMPFILE && \
                $mv -f $TMPFILE $1
            return 0
        else
            return 2
        fi
    else
        return 1
    fi
}

#
# Change the global $TTL line in a zone file
#
change_global_ttl() {
    ttl=$1
    file=$2

    TMPFILE=`$mktemp $file.XXXXXX`
    $sed -e 's/^\$TTL.*$/$TTL '$ttl'/' < $file > $TMPFILE && \
        $mv -f $TMPFILE $file
}

#
# Change the TTL of an SOA record
#
# This expects the TTL line to be alone on a line, surrounded by space
# and followed by a closing parenthesis, which should work in most
# cases
change_soa_ttl() {
    ttl=$1
    file=$2
    TMPFILE=`$mktemp $file.XXXXXX`
    $sed -e 's/\([[:space:]][[:space:]]*\)[0-9][0-9]*[DdHhMm]\?\([[:space:]]*)\)/\1'$ttl'\2/' < $file > $TMPFILE && \
        $mv -f $TMPFILE $file
}

# do everything
for i; do
    echo "updating ttl to $NEW_TTL in $i" >&2
    change_global_ttl $NEW_TTL $i
    change_soa_ttl $NEW_TTL $i
    increment_serial $i
done