<?php
/**
* Canonical API to handle WordPress Redirecting
*
* Based on "Permalink Redirect" from Scott Yang and "Enforce www. Preference"
* by Mark Jaquith
*
* @package WordPress
* @since 2.3.0
*/
/**
* Redirects incoming links to the proper URL based on the site url.
*
* Search engines consider www.somedomain.com and somedomain.com to be two
* different URLs when they both go to the same location. This SEO enhancement
* prevents penalty for duplicate content by redirecting all incoming links to
* one or the other.
*
* Prevents redirection for feeds, trackbacks, searches, and
* admin URLs. Does not redirect on non-pretty-permalink-supporting IIS 7+,
* page/post previews, WP admin, Trackbacks, robots.txt, favicon.ico, searches,
* or on POST requests.
*
* Will also attempt to find the correct link when a user enters a URL that does
* not exist based on exact WordPress query. Will instead try to parse the URL
* or query in an attempt to figure the correct page to go to.
*
* @since 2.3.0
*
* @global WP_Rewrite $wp_rewrite WordPress rewrite component.
* @global bool $is_IIS
* @global WP_Query $wp_query WordPress Query object.
* @global wpdb $wpdb WordPress database abstraction object.
* @global WP $wp Current WordPress environment instance.
*
* @param string $requested_url Optional. The URL that was requested, used to
* figure if redirect is needed.
* @param bool $do_redirect Optional. Redirect to the new URL.
* @return string|void The string of the URL, if redirect needed.
*/
function redirect_canonical( $requested_url = null, $do_redirect = true ) {
global $wp_rewrite, $is_IIS, $wp_query, $wpdb, $wp;
if ( isset( $_SERVER['REQUEST_METHOD'] ) && ! in_array( strtoupper( $_SERVER['REQUEST_METHOD'] ), array( 'GET', 'HEAD' ), true ) ) {
return;
}
/*
* If we're not in wp-admin and the post has been published and preview nonce
* is non-existent or invalid then no need for preview in query.
*/
if ( is_preview() && get_query_var( 'p' ) && 'publish' === get_post_status( get_query_var( 'p' ) ) ) {
if ( ! isset( $_GET['preview_id'] )
|| ! isset( $_GET['preview_nonce'] )
|| ! wp_verify_nonce( $_GET['preview_nonce'], 'post_preview_' . (int) $_GET['preview_id'] )
) {
$wp_query->is_preview = false;
}
}
if ( is_admin() || is_search() || is_preview() || is_trackback() || is_favicon()
|| ( $is_IIS && ! iis7_supports_permalinks() )
) {
return;
}
if ( ! $requested_url && isset( $_SERVER['HTTP_HOST'] ) ) {
// Build the URL in the address bar.
$requested_url = is_ssl() ? 'https://' : 'http://';
$requested_url .= $_SERVER['HTTP_HOST'];
$requested_url .= $_SERVER['REQUEST_URI'];
}
$original = parse_url( $requested_url );
if ( false === $original ) {
return;
}
$redirect = $original;
$redirect_url = false;
$redirect_obj = false;
// Notice fixing.
if ( ! isset( $redirect['path'] ) ) {
$redirect['path'] = '';
}
if ( ! isset( $redirect['query'] ) ) {
$redirect['query'] = '';
}
/*
* If the original URL ended with non-breaking spaces, they were almost
* certainly inserted by accident. Let's remove them, so the reader doesn't
* see a 404 error with no obvious cause.
*/
$redirect['path'] = preg_replace( '|(%C2%A0)+$|i', '', $redirect['path'] );
// It's not a preview, so remove it from URL.
if ( get_query_var( 'preview' ) ) {
$redirect['query'] = remove_query_arg( 'preview', $redirect['query'] );
}
$post_id = get_query_var( 'p' );
if ( is_feed() && $post_id ) {
$redirect_url = get_post_comments_feed_link( $post_id, get_query_var( 'feed' ) );
$redirect_obj = get_post( $post_id );
if ( $redirect_url ) {
$redirect['query'] = _remove_qs_args_if_not_in_url(
$redirect['query'],
array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type', 'feed' ),
$redirect_url
);
$redirect['path'] = parse_url( $redirect_url, PHP_URL_PATH );
}
}
if ( is_singular() && $wp_query->post_count < 1 && $post_id ) {
$vars = $wpdb->get_resul