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