#! /bin/sh
# /etc/rc.d/rc.vhostnames: Update DynDNS from apache configs
# Copyright 2013 Sergey Poznyakoff
#
# 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 3, 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/>.

### Configurable part begins ###
# Set these:
HOSTNAME=
ZONE=
NSKEY=
#TTL=
### Configurable part ends ###

CNAMESLIST=/var/run/nssetup
get_cnames() {
    awk -v pattern='.*\\.'"$ZONE" '
           BEGIN {
	        npat = split(pattern,apat);
	   }
           { sub(/^[ \t][ \t]*/,"") }
           /#/ { sub(/#.*/, "") }
           NF==0 { next }
           /^ServerName/ {
	        for (j = 1; j <= npat; j++)
	          if (match($2, apat[j]))
		    print $2
	   }
           /^ServerAlias/ {
	        for (i = 2; i <= NF; i++)
	          for (j = 1; j <= npat; j++)
	            if (match($i, apat[j]))
	              print $i
 	   }' /etc/httpd/sites-enabled/* | 
      tr ' ' '\n' | sed '/^$/d' | sort | uniq
}

update_dns() {
    if test ${dry_run:-no} = yes; then
	echo "$0: ignoring DNS updates:"
        cat 
    else 
        nsupdate -k $NSKEY 2>&1 | grep -v "update failed: NXRRSET"
    fi
}

nscleanup() {
    if test -s "$CNAMESLIST"; then
        echo "$0: Removing DNS CNAME records"
        while read cname
        do
	    test -z "$cname" && continue
	    cat <<EOT
prereq yxrrset $cname CNAME
update delete $cname CNAME
send
EOT
        done < $CNAMESLIST | update_dns
        rm $CNAMESLIST
    fi
}

nssetup() {
    nscleanup
    echo "$0: Updating DNS CNAME records"
    echo "$*" | tr ' ' '\n' > $CNAMESLIST
    for cname 
    do
	test -z "$cname" && continue
	cat <<EOT
prereq yxrrset $cname CNAME
update delete $cname CNAME
send
update add $cname ${TTL:-86400} CNAME $HOSTNAME
send
EOT
    done < $CNAMESLIST | update_dns
}

update_cnames() {
    cnames=$(get_cnames)
    if test -r $CNAMESLIST; then
	if test -n "$cnames" && 
            echo "$cnames" | cmp - $CNAMESLIST >/dev/null; then
	    return
	fi
    else
	if test -z "$cnames"; then
	    return
	fi
    fi
    echo "$cnames" | diff - $CNAMESLIST 
    nssetup $cnames
}

if test -n "$DIRCOND_GENEV_NAME"; then
    case $(pwd) in
    /etc/httpd/sites-available)
	for file in /etc/httpd/sites-enabled/*
	do
	    if test -h $file; then
		s=$(readlink -f $file)
		if test "$s" = /etc/httpd/sites-available/$DIRCOND_FILE; then
		    update_cnames
		    break
		fi
	    fi
	done
	;;
    /etc/httpd/sites-enabled)
	update_cnames
    esac
else
    case $1 in
    start|restart|force-restart|reload)
        cnames=$(get_cnames)
        if test -n "$cnames"; then
            nssetup $cnames
        fi
        ;;
    stop)
        nscleanup;;
    status)
        echo >&2 "$0: status ignored";;
    *)  echo >&2 "usage: $0 {start|restart|force-restart|reload|stop}"
        echo >&2 "       can be called as dircond(1) handler"
    esac
fi