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- <?php
- /**
- * Canonical API to handle WordPress Redirecting
- *
- * Based on "Permalink Redirect" from Scott Yang and "Enforce www. Preference"
- * by Mark Jaquith
- *
- * @author Scott Yang
- * @author Mark Jaquith
- * @package WordPress
- * @since 2.3
- */
-
- /**
- * 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 penality for duplicate content by redirecting all incoming links to
- * one or the other.
- *
- * Prevents redirection for feeds, trackbacks, searches, comment popup, and
- * admin URLs. Does not redirect on IIS, page/post previews, and on form data.
- *
- * 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
- * @uses $wp_rewrite
- * @uses $is_IIS
- *
- * @param string $requested_url Optional. The URL that was requested, used to
- * figure if redirect is needed.
- * @param bool $do_redirect Optional. Redirect to the new URL.
- * @return null|false|string Null, if redirect not needed. False, if redirect
- * not needed or the string of the URL
- */
- function redirect_canonical($requested_url=null, $do_redirect=true) {
- global $wp_rewrite, $is_IIS;
-
- if ( is_feed() || is_trackback() || is_search() || is_comments_popup() || is_admin() || $is_IIS || ( isset($_POST) && count($_POST) ) || is_preview() || is_robots() )
- return;
-
- if ( !$requested_url ) {
- // build the URL in the address bar
- $requested_url = ( isset($_SERVER['HTTPS'] ) && strtolower($_SERVER['HTTPS']) == 'on' ) ? 'https://' : 'http://';
- $requested_url .= $_SERVER['HTTP_HOST'];
- $requested_url .= $_SERVER['REQUEST_URI'];
- }
-
- $original = @parse_url($requested_url);
- if ( false === $original )
- return;
-
- // Some PHP setups turn requests for / into /index.php in REQUEST_URI
- $original['path'] = preg_replace('|/index\.php$|', '/', $original['path']);
-
- $redirect = $original;
- $redirect_url = false;
-
- // These tests give us a WP-generated permalink
- if ( is_404() ) {
- $redirect_url = redirect_guess_404_permalink();
- } elseif ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() ) {
- // rewriting of old ?p=X, ?m=2004, ?m=200401, ?m=20040101
- if ( is_single() && isset($_GET['p']) ) {
- if ( $redirect_url = get_permalink(get_query_var('p')) )
- $redirect['query'] = remove_query_arg('p', $redirect['query']);
- } elseif ( is_page() && isset($_GET['page_id']) ) {
- if ( $redirect_url = get_permalink(get_query_var('page_id')) )
- $redirect['query'] = remove_query_arg('page_id', $redirect['query']);
- } elseif ( isset($_GET['m']) && ( is_year() || is_month() || is_day() ) ) {
- $m = get_query_var('m');
- switch ( strlen($m) ) {
- case 4: // Yearly
- $redirect_url = get_year_link($m);
- break;
- case 6: // Monthly
- $redirect_url = get_month_link( substr($m, 0, 4), substr($m, 4, 2) );
- break;
- case 8: // Daily
- $redirect_url = get_day_link(substr($m, 0, 4), substr($m, 4, 2), substr($m, 6, 2));
- break;
- }
- if ( $redirect_url )
- $redirect['query'] = remove_query_arg('m', $redirect['query']);
- // now moving on to non ?m=X year/month/day links
- } elseif ( is_day() && get_query_var('year') && get_query_var('monthnum') && isset($_GET['day']) ) {
- if ( $redirect_url = get_day_link(get_query_var('year'), get_query_var('monthnum'), get_query_var('day')) )
- $redirect['query'] = remove_query_arg(array('year', 'monthnum', 'day'), $redirect['query']);
- } elseif ( is_month() && get_query_var('year') && isset($_GET['monthnum']) ) {
- if ( $redirect_url = get_month_link(get_query_var('year'), get_query_var('monthnum')) )
- $redirect['query'] = remove_query_arg(array('year', 'monthnum'), $redirect['query']);
- } elseif ( is_year() && isset($_GET['year']) ) {
- if ( $redirect_url = get_year_link(get_query_var('year')) )
- $redirect['query'] = remove_query_arg('year', $redirect['query']);
- } elseif ( is_category() && isset($_GET['cat']) ) {
- if ( $redirect_url = get_category_link(get_query_var('cat')) )
- $redirect['query'] = remove_query_arg('cat', $redirect['query']);
- } elseif ( is_author() && isset($_GET['author']) ) {
- $author = get_userdata(get_query_var('author'));
- if ( false !== $author && $redirect_url = get_author_link(false, $author->ID, $author->user_nicename) )
- $redirect['query'] = remove_query_arg('author', $redirect['author']);
- }
-
- // paging
- if ( $paged = get_query_var('paged') ) {
- if ( $paged > 0 ) {
- if ( !$redirect_url )
- $redirect_url = $requested_url;
- $paged_redirect = @parse_url($redirect_url);
- $paged_redirect['path'] = preg_replace('|/page/[0-9]+?(/+)?$|', '/', $paged_redirect['path']); // strip off any existing paging
- $paged_redirect['path'] = preg_replace('|/index.php/?$|', '/', $paged_redirect['path']); // strip off trailing /index.php/
- if ( $paged > 1 && !is_single() ) {
- $paged_redirect['path'] = trailingslashit($paged_redirect['path']);
- if ( $wp_rewrite->using_index_permalinks() && strpos($paged_redirect['path'], '/index.php/') === false )
- $paged_redirect['path'] .= 'index.php/';
- $paged_redirect['path'] .= user_trailingslashit("page/$paged", 'paged');
- } elseif ( !is_home() && !is_single() ){
- $paged_redirect['path'] = user_trailingslashit($paged_redirect['path'], 'paged');
- }
- $redirect_url = $paged_redirect['scheme'] . '://' . $paged_redirect['host'] . $paged_redirect['path'];
- $redirect['path'] = $paged_redirect['path'];
- }
- $redirect['query'] = remove_query_arg('paged', $redirect['query']);
- }
- }
-
- // tack on any additional query vars
- if ( $redirect_url && $redirect['query'] ) {
- if ( strpos($redirect_url, '?') !== false )
- $redirect_url .= '&';
- else
- $redirect_url .= '?';
- $redirect_url .= $redirect['query'];
- }
-
- if ( $redirect_url )
- $redirect = @parse_url($redirect_url);
-
- // www.example.com vs example.com
- $user_home = @parse_url(get_option('home'));
- if ( isset($user_home['host']) )
- $redirect['host'] = $user_home['host'];
-
- // Handle ports
- if ( isset($user_home['port']) )
- $redirect['port'] = $user_home['port'];
- else
- unset($redirect['port']);
-
- // trailing /index.php/
- $redirect['path'] = preg_replace('|/index.php/$|', '/', $redirect['path']);
-
- // strip /index.php/ when we're not using PATHINFO permalinks
- if ( !$wp_rewrite->using_index_permalinks() )
- $redirect['path'] = str_replace('/index.php/', '/', $redirect['path']);
-
- // trailing slashes
- if ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() && !is_404() && (!is_home() || ( is_home() && (get_query_var('paged') > 1) ) ) ) {
- $user_ts_type = '';
- if ( get_query_var('paged') > 0 ) {
- $user_ts_type = 'paged';
- } else {
- foreach ( array('single', 'category', 'page', 'day', 'month', 'year') as $type ) {
- $func = 'is_' . $type;
- if ( call_user_func($func) ) {
- $user_ts_type = $type;
- break;
- }
- }
- }
- $redirect['path'] = user_trailingslashit($redirect['path'], $user_ts_type);
- } elseif ( is_home() ) {
- $redirect['path'] = trailingslashit($redirect['path']);
- }
-
- // Always trailing slash the 'home' URL
- if ( $redirect['path'] == $user_home['path'] )
- $redirect['path'] = trailingslashit($redirect['path']);
-
- // Ignore differences in host capitalization, as this can lead to infinite redirects
- if ( strtolower($original['host']) == strtolower($redirect['host']) )
- $redirect['host'] = $original['host'];
-
- if ( array($original['host'], $original['port'], $original['path'], $original['query']) !== array($redirect['host'], $redirect['port'], $redirect['path'], $redirect['query']) ) {
- $redirect_url = $redirect['scheme'] . '://' . $redirect['host'];
- if ( isset($redirect['port']) )
- $redirect_url .= ':' . $redirect['port'];
- $redirect_url .= $redirect['path'];
- if ( $redirect['query'] )
- $redirect_url .= '?' . $redirect['query'];
- }
-
- if ( !$redirect_url || $redirect_url == $requested_url )
- return false;
-
- // Note that you can use the "redirect_canonical" filter to cancel a canonical redirect for whatever reason by returning FALSE
- $redirect_url = apply_filters('redirect_canonical', $redirect_url, $requested_url);
-
- if ( !$redirect_url || $redirect_url == $requested_url ) // yes, again -- in case the filter aborted the request
- return false;
-
- if ( $do_redirect ) {
- // protect against chained redirects
- if ( !redirect_canonical($redirect_url, false) ) {
- wp_redirect($redirect_url, 301);
- exit();
- } else {
- return false;
- }
- } else {
- return $redirect_url;
- }
- }
-
- /**
- * Attempts to guess correct post based on query vars
- *
- * @since 2.3
- * @uses $wpdb
- *
- * @return bool|string Returns False, if it can't find post, returns correct
- * location on success.
- */
- function redirect_guess_404_permalink() {
- global $wpdb;
- if ( !get_query_var('name') )
- return false;
-
- $where = $wpdb->prepare("post_name LIKE %s", get_query_var('name') . '%');
-
- // if any of year, monthnum, or day are set, use them to refine the query
- if ( get_query_var('year') )
- $where .= $wpdb->prepare(" AND YEAR(post_date) = %d", get_query_var('year'));
- if ( get_query_var('monthnum') )
- $where .= $wpdb->prepare(" AND MONTH(post_date) = %d", get_query_var('monthnum'));
- if ( get_query_var('day') )
- $where .= $wpdb->prepare(" AND DAYOFMONTH(post_date) = %d", get_query_var('day'));
-
- $post_id = $wpdb->get_var("SELECT ID FROM $wpdb->posts WHERE $where AND post_status = 'publish'");
- if ( !$post_id )
- return false;
- return get_permalink($post_id);
- }
-
- add_action('template_redirect', 'redirect_canonical');
-
- ?>
-