Force replace original domain by mapped domain for WPMU Domain Mapping

force-domain-mapping.php

<?php 
/*
  Plugin Name:  BEA Domain Mapping
  Description:  Always force replace original domain by mapping domain
  Plugin URI:   http://www.beapi.fr
  Version:      1.0
  Author:       BeAPI
  Author URI:   http://www.beapi.fr

  /*
  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, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

ob_start( 'ob_domain_mapping_body' );
function ob_domain_mapping_body( $html ) {
	global $wpdb;
	
	if ( !function_exists('domain_mapping_siteurl') ) {
		return false;
	}
	
	$orig_url = get_original_url( 'siteurl' );
	$url = domain_mapping_siteurl( 'NA' );
	if ( 'NA' == $url ) {
		return $html;
	}
	
	return str_replace( $orig_url, $url, $html );
}