How to add CORS support to Wordpress RSS2 feed?

Question

I am trying to add CORS (http://enable-cors.org/) support to an RSS2 feed within a custom Wordpress theme. I have tried the following, all to no avail:

1. Following the instructions on https://web.archive.org/web/20140314152828/http://bowdenweb.com:80/wp/2011/05/how-to-enable-cors-in-wordpress.html, I attempted to modify the theme's header.php file and add the following code to it:

   header("Access-Control-Allow-Origin: *");

   This was successful in adding the CORS header to the Wordpress posts, but not to the RSS2 feed.

2. Then, I attempted to use the "Plugin API / Action Reference", i.e. the add_action function (http://codex.wordpress.org/Plugin_API/Action_Reference).

   I added the following code to header.php:

   function add_cors_headers()
   {
       header("Access-Control-Allow-Origin: *");
   }
   
   add_action('rss2_head','add_cors_headers');
   

Again, no success. Now I am at a dead end. Any ideas?

Answer 1

You could do it like this with a plugin or by adding to functions. I think that ends up being cleaner.

add_action( 'pre_get_posts', 'add_header_origin' );

function add_header_origin() {
    if (is_feed()){
        header( 'Access-Control-Allow-Origin: *' );
    }
}            

Answer 2

Copy the original rss-template "wp-includes/feed-rss2.php" to your theme directory and activate it by adding this code to your functions.php:

remove_all_actions( 'do_feed_rss2' );
add_action( 'do_feed_rss2', 'my_feed_rss2', 10, 1 );

function my_feed_rss2( $for_comments ) {
    $rss_template = get_stylesheet_directory() . '/feed-rss2.php';

    if( file_exists( $rss_template ) )
        load_template( $rss_template );
    else
        do_feed_rss2( $for_comments ); // Call default function
}

Then you can modify your rss-template and add the header like mentioned by jefffederman.