#!/bin/sh
# Synchronize a dns server with alternc's remote server : 
# the configuration files contains definitions for remote masters.

CONFDIR=/etc/alternc/slavedns
CACHEDIR=/var/cache/slavedns
BINDDIR=/etc/bind/slavedns
BINDINCLUDE=/etc/bind/slavedns.conf
WGETRC=${HOME}/.wgetrc
WGET=wget
WGETFLAGS="-q"
NAMED="/etc/init.d/bind restart" 
DEFAULTS="defaults.conf"
DEFAULTSFILE="${CONFDIR}/${DEFAULTS}"
DEBUG=false

usage() {

    cat <<EOF
$0 [ -f ] [ -d ] [ -h ] [ config ]

Performs a sync of the list of domains to replicate from master.

Multiple master servers can be used, one per file in $CONFDIR
If a config file is specified on the command line, only that server
will be synced. The $BINDINCLUDE file will also be generated to include
the right configuration.

-f: refresh domain list even if it hasn't changed
-d: show everything we're doing
-h: this help
EOF
}

for i
do
    case "$i" 
    in
         -f)
             FORCE=yes
             ;;
         -d)
             DEBUG=true
             ;;
         -h)
             usage
             exit 0
             ;;
         *)
	         CONFIGS="${CONFIGS} ${i}"
             ;;
    esac
done

cd $CONFDIR

if [ -z "$CONFIGS" ]
then
    CONFIGS=`ls $CONFDIR | grep -v ~`
fi

TIMEOUT=5

CreateBindConf() {
    CFILE="$1"
    # create a new config for this host, in a tempfile
    while read domain
    do
      # check if the data is valid, this will also display the domain in debug mode
      if echo $domain | grep -i '^\([a-z0-9]\([-a-z0-9]*[a-z0-9]\)\?\.\)*[a-z0-9]\([-a-z0-9]*[a-z0-9]\)$'
      then
          echo "validated domain $domain" | MaybeCat
      else
          echo invalid domain listing: $domain, skipping file $CFILE >&2
          rm -f ${BINDDIR}/${CFILE}.$$
          return
      fi
      cat >> ${BINDDIR}/${CFILE}.$$ <<EOF
zone "$domain" {
    type slave;
    allow-query { any; };
    file "$domain";
    masters { ${MASTERIP}; };
};
EOF
    done < ${CACHEDIR}/${CFILE}
    mv ${BINDDIR}/${CFILE}.$$ ${BINDDIR}/${CFILE}
    INCLUDE_STR="include \"${BINDDIR}/${CFILE}\";"

    grep -q "${INCLUDE_STR}" ${BINDINCLUDE} || echo ${INCLUDE_STR} >>${BINDINCLUDE}
}

SetWgetPass() {
    USER="$1"
    PASS="$2"
    if [ -e ${WGETRC} ]; then
        mv ${WGETRC} ${WGETRC}.$$
    fi
    touch ${WGETRC}
    chmod og-r ${WGETRC}
    cat >> ${WGETRC} <<EOF
http_user = ${USER}
http_passwd = ${PASS}
EOF
}

ResetWgetConf() {
    mv -f ${WGETRC}.$$ ${WGETRC} 2>/dev/null || rm -f ${WGETRC}
}

MaybeCat() {
    if $DEBUG
    then
        cat
    else
        cat > /dev/null
    fi
    return 0
}

# Main procedure : parse each config file and download the raw slave list.
# if something changed in a list, call CreateBindConf $i 

RELOAD=""

for conf in ${CONFIGS}
do
  [ "${DEFAULTS}" = "${conf}" -o "slavedns.conf" = "${conf}" ] && continue
  URL=""
  # source defaults
  . ${DEFAULTSFILE}
  # source this site's config
  . $CONFDIR/${conf}
  if [ -z "$URL" ]
  then
      if [ -z "$PROTOCOL" ]
      then
          if [ "$SSL" ]
          then
              PROTOCOL=https
          else
              PROTOCOL=http
          fi
      fi
      URL=${PROTOCOL}://${HOST}/admin/domlist.php
  fi

  if [ -z "$URL" -a -z "$HOST" -o -z "$MASTERIP" ]
  then
      echo "error in the config file '${conf}'" >&2
  else
      touch ${CACHEDIR}/${conf}
      rm -f ${CACHEDIR}/${conf}.temp
      [ "${LOGIN}" ] && SetWgetPass ${LOGIN} ${PASSWORD}
      ${WGET} ${URL} ${WGETFLAGS} -O ${CACHEDIR}/${conf}.temp -t 1 -T ${TIMEOUT} 2>&1 | MaybeCat
      [ "${LOGIN}" ] && ResetWgetConf
      if [ -s "${CACHEDIR}/${conf}.temp" ]
      then
          # If the slave file has changed, synchronize it.
	  if ! [ "${FORCE}" ] && cmp ${CACHEDIR}/${conf}.temp ${CACHEDIR}/${conf} > /dev/null
	  then
	      echo "no change found for '${conf}'"
	  else
	          echo "change detected for '${conf}', applying"
       		   mv -f ${CACHEDIR}/${conf}.temp ${CACHEDIR}/${conf}
       		   # Now parse the slave file and send it to /etc/bind/slavedns
       		   CreateBindConf ${conf}
       		   if named-checkconf ${BINDDIR}/${conf}
		   then
       		   	RELOAD="yes"
		else
    			echo "error: file ${conf} is not correct"
		fi
	  fi
      else
          echo "downloaded file for '${conf}' has zero size"
          rm -f ${CACHEDIR}/${conf}.temp
      fi
  fi
done	 # Main loop on config files

if [ "$RELOAD" ]
then
    ${NAMED} >/dev/null
fi