redirect-favicon-request.php

<?php

add_action( 'wp_head', function() {
?><link rel="shortcut icon" href="<?php echo site_url( 'favicon.ico' ); ?>" /><?php
});


$redirect_favicon = new Redirect_Favicon();
class Redirect_Favicon {

	function __construct() {
		add_action( 'wp_loaded', array( &$this, 'wp_loaded' ) );
		add_filter( 'rewrite_rules_array', array( &$this, 'rewrite_rules_array' ) );
		add_filter( 'query_vars', array( &$this, 'query_vars' ) );
		add_action( 'pre_get_posts', array( &$this, 'pre_get_posts' ) );

	}

	// flush_rules() if our rules are not yet included
	function wp_loaded() {
		$rules = get_option( 'rewrite_rules' );

		if ( ! isset( $rules['^favicon.ico$'] ) ) {
			global $wp_rewrite;
			$wp_rewrite->flush_rules();
		}
	}

	// Adding a new rule
	function rewrite_rules_array( $rules ) {
		$newrules = array();
		$newrules['^favicon.ico$'] = 'index.php?favicon';
		return $newrules + $rules;
	}

	// Adding the id var so that WP recognizes it
	function query_vars( $vars ) {
		array_push( $vars, 'favicon' );
		return $vars;
	}

	function pre_get_posts( $query ) {
		if ( is_admin() ) return;

		if ( ! isset( $query->query_vars['favicon'] ) ) return;

		wp_safe_redirect( plugins_url('favicon.ico', __FILE__ ) );
		exit;
	}
}