Admin Links in Multisite Always go to Original Domain

admin-mu-link-orig-domain.php

<?php
/**
 * function wpmark_admin_url_to_unmapped_domain()
 *
 * makes all the admin links on the site go to the
 * original unmapped domain.
 */
function wpmark_admin_url_to_unmapped_domain( $url, $path, $blog_id ) {
	
	/* get the original site url */
	$orig_url = get_original_url( $url );
	
	/* check if admin should be https */
	if( force_ssl_admin() ) {
		
		/* replace all instances of http with https in the original site url */
		$orig_url = str_replace( 'http://', 'https://', $orig_url );
	
	}
	
	/* return the new admin url include any path passed after it */
	return trailingslashit( $orig_url ) . 'wp-admin/' . $path;
	
}
?>