<?php
/*
Plugin Name: Enable external permalinks
Plugin URI: http://blog.clearskys.net/2009/01/16/how-to-point-your-post-permalink-to-an-external-site
Description: This plugin will allow you to change the post permalink for your posts/pages to an external sites URL
Author: Barry at clearskys.net
Version: 0.1
Author URI: http://blog.clearskys.net/
*/


function cs_external_permalink($permalink) {
		global $post;
		
		$thePostID = $post->ID;
		$post_id = get_post($thePostID);
		$title = $post_id->post_title;
		
		$post_keys = array(); $post_val  = array();
		$post_keys = get_post_custom_keys($thePostID);

		if (!empty($post_keys)) {
	  	  foreach ($post_keys as $pkey) {
	    	    if ($pkey=='url1' || $pkey=='title_url' || $pkey=='url_title'  || $pkey=='external') {
	      	      $post_val = get_post_custom_values($pkey);
	    	    }
	  	  }
	  	  if (empty($post_val)) {
	    	    $link = $permalink;
	  	  } else {
	    	    $link = $post_val[0];
	  	  }
		} else {
	  	  $link = $permalink;
		}
		
		return $link;
	
}

add_filter('the_permalink','cs_external_permalink');
add_filter('the_permalink_rss','cs_external_permalink');

?>