3 * Canonical API to handle WordPress Redirecting
5 * Based on "Permalink Redirect" from Scott Yang and "Enforce www. Preference"
13 * Redirects incoming links to the proper URL based on the site url.
15 * Search engines consider www.somedomain.com and somedomain.com to be two
16 * different URLs when they both go to the same location. This SEO enhancement
17 * prevents penality for duplicate content by redirecting all incoming links to
20 * Prevents redirection for feeds, trackbacks, searches, comment popup, and
21 * admin URLs. Does not redirect on IIS, page/post previews, and on form data.
23 * Will also attempt to find the correct link when a user enters a URL that does
24 * not exist based on exact WordPress query. Will instead try to parse the URL
25 * or query in an attempt to figure the correct page to go to.
31 * @param string $requested_url Optional. The URL that was requested, used to
32 * figure if redirect is needed.
33 * @param bool $do_redirect Optional. Redirect to the new URL.
34 * @return null|false|string Null, if redirect not needed. False, if redirect
35 * not needed or the string of the URL
37 function redirect_canonical($requested_url=null, $do_redirect=true) {
38 global $wp_rewrite, $is_IIS, $wp_query, $wpdb;
40 if ( is_trackback() || is_search() || is_comments_popup() || is_admin() || $is_IIS || ( isset($_POST) && count($_POST) ) || is_preview() || is_robots() )
43 if ( !$requested_url ) {
44 // build the URL in the address bar
45 $requested_url = is_ssl() ? 'https://' : 'http://';
46 $requested_url .= $_SERVER['HTTP_HOST'];
47 $requested_url .= $_SERVER['REQUEST_URI'];
50 $original = @parse_url($requested_url);
51 if ( false === $original )
54 // Some PHP setups turn requests for / into /index.php in REQUEST_URI
55 // See: http://trac.wordpress.org/ticket/5017
56 // See: http://trac.wordpress.org/ticket/7173
58 // $original['path'] = preg_replace('|/index\.php$|', '/', $original['path']);
60 $redirect = $original;
61 $redirect_url = false;
64 if ( !isset($redirect['path']) )
65 $redirect['path'] = '';
66 if ( !isset($redirect['query']) )
67 $redirect['query'] = '';
69 if ( is_singular() && 1 > $wp_query->post_count && ($id = get_query_var('p')) ) {
71 $vars = $wpdb->get_results( $wpdb->prepare("SELECT post_type, post_parent FROM $wpdb->posts WHERE ID = %d", $id) );
73 if ( isset($vars[0]) && $vars = $vars[0] ) {
74 if ( 'revision' == $vars->post_type && $vars->post_parent > 0 )
75 $id = $vars->post_parent;
77 if ( $redirect_url = get_permalink($id) )
78 $redirect['query'] = remove_query_arg(array('p', 'page_id', 'attachment_id', 'post_type'), $redirect['query']);
82 // These tests give us a WP-generated permalink
85 // Redirect ?page_id, ?p=, ?attachment_id= to their respective url's
86 $id = max( get_query_var('p'), get_query_var('page_id'), get_query_var('attachment_id') );
87 if ( $id && $redirect_post = get_post($id) ) {
88 $post_type_obj = get_post_type_object($redirect_post->post_type);
89 if ( $post_type_obj->public ) {
90 $redirect_url = get_permalink($redirect_post);
91 $redirect['query'] = remove_query_arg(array('p', 'page_id', 'attachment_id', 'post_type'), $redirect['query']);
95 if ( ! $redirect_url )
96 $redirect_url = redirect_guess_404_permalink();
98 } elseif ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() ) {
99 // rewriting of old ?p=X, ?m=2004, ?m=200401, ?m=20040101
100 if ( is_attachment() && !empty($_GET['attachment_id']) && ! $redirect_url ) {
101 if ( $redirect_url = get_attachment_link(get_query_var('attachment_id')) )
102 $redirect['query'] = remove_query_arg('attachment_id', $redirect['query']);
103 } elseif ( is_single() && !empty($_GET['p']) && ! $redirect_url ) {
104 if ( $redirect_url = get_permalink(get_query_var('p')) )
105 $redirect['query'] = remove_query_arg(array('p', 'post_type'), $redirect['query']);
106 } elseif ( is_single() && !empty($_GET['name']) && ! $redirect_url ) {
107 if ( $redirect_url = get_permalink( $wp_query->get_queried_object_id() ) )
108 $redirect['query'] = remove_query_arg('name', $redirect['query']);
109 } elseif ( is_page() && !empty($_GET['page_id']) && ! $redirect_url ) {
110 if ( $redirect_url = get_permalink(get_query_var('page_id')) )
111 $redirect['query'] = remove_query_arg('page_id', $redirect['query']);
112 } elseif ( is_page() && !is_feed() && isset($wp_query->queried_object) && 'page' == get_option('show_on_front') && $wp_query->queried_object->ID == get_option('page_on_front') && ! $redirect_url ) {
113 $redirect_url = home_url('/');
114 } elseif ( is_home() && !empty($_GET['page_id']) && 'page' == get_option('show_on_front') && get_query_var('page_id') == get_option('page_for_posts') && ! $redirect_url ) {
115 if ( $redirect_url = get_permalink(get_option('page_for_posts')) )
116 $redirect['query'] = remove_query_arg('page_id', $redirect['query']);
117 } elseif ( !empty($_GET['m']) && ( is_year() || is_month() || is_day() ) ) {
118 $m = get_query_var('m');
119 switch ( strlen($m) ) {
121 $redirect_url = get_year_link($m);
124 $redirect_url = get_month_link( substr($m, 0, 4), substr($m, 4, 2) );
127 $redirect_url = get_day_link(substr($m, 0, 4), substr($m, 4, 2), substr($m, 6, 2));
131 $redirect['query'] = remove_query_arg('m', $redirect['query']);
132 // now moving on to non ?m=X year/month/day links
133 } elseif ( is_day() && get_query_var('year') && get_query_var('monthnum') && !empty($_GET['day']) ) {
134 if ( $redirect_url = get_day_link(get_query_var('year'), get_query_var('monthnum'), get_query_var('day')) )
135 $redirect['query'] = remove_query_arg(array('year', 'monthnum', 'day'), $redirect['query']);
136 } elseif ( is_month() && get_query_var('year') && !empty($_GET['monthnum']) ) {
137 if ( $redirect_url = get_month_link(get_query_var('year'), get_query_var('monthnum')) )
138 $redirect['query'] = remove_query_arg(array('year', 'monthnum'), $redirect['query']);
139 } elseif ( is_year() && !empty($_GET['year']) ) {
140 if ( $redirect_url = get_year_link(get_query_var('year')) )
141 $redirect['query'] = remove_query_arg('year', $redirect['query']);
142 } elseif ( is_author() && !empty($_GET['author']) && preg_match( '|^[0-9]+$|', $_GET['author'] ) ) {
143 $author = get_userdata(get_query_var('author'));
144 if ( false !== $author && $redirect_url = get_author_posts_url($author->ID, $author->user_nicename) )
145 $redirect['query'] = remove_query_arg('author', $redirect['query']);
146 } elseif ( is_category() || is_tag() || is_tax() ) { // Terms (Tags/categories)
149 foreach ( array('category__in', 'category__not_in', 'category__and', 'post__in', 'post__not_in',
150 'tag__in', 'tag__not_in', 'tag__and', 'tag_slug__in', 'tag_slug__and') as $key )
151 $term_count += count($wp_query->query_vars[$key]);
153 $obj = $wp_query->get_queried_object();
155 if ( $term_count <= 1 && !empty($obj->term_id) && ( $tax_url = get_term_link((int)$obj->term_id, $obj->taxonomy) )
156 && !is_wp_error($tax_url) && $redirect['query'] ) {
157 if ( is_category() ) {
158 $redirect['query'] = remove_query_arg( array( 'category_name', 'category', 'cat'), $redirect['query']);
159 } elseif ( is_tag() ) {
160 $redirect['query'] = remove_query_arg( array( 'tag', 'tag_id'), $redirect['query']);
161 } elseif ( is_tax() ) { // Custom taxonomies will have a custom query var, remove those too:
162 $tax = get_taxonomy( $obj->taxonomy );
163 if ( false !== $tax->query_var)
164 $redirect['query'] = remove_query_arg($tax->query_var, $redirect['query']);
166 $redirect['query'] = remove_query_arg( array( 'term', 'taxonomy'), $redirect['query']);
169 $tax_url = parse_url($tax_url);
170 if ( ! empty($tax_url['query']) ) { // Custom taxonomies may only be accessable via ?taxonomy=..&term=..
171 parse_str($tax_url['query'], $query_vars);
172 $redirect['query'] = add_query_arg($query_vars, $redirect['query']);
173 } else { // Taxonomy is accessable via a "pretty-URL"
174 $redirect['path'] = $tax_url['path'];
178 } elseif ( is_single() && strpos($wp_rewrite->permalink_structure, '%category%') !== false ) {
179 $category = get_category_by_path(get_query_var('category_name'));
180 $post_terms = wp_get_object_terms($wp_query->get_queried_object_id(), 'category', array('fields' => 'tt_ids'));
181 if ( (!$category || is_wp_error($category)) || ( !is_wp_error($post_terms) && !empty($post_terms) && !in_array($category->term_taxonomy_id, $post_terms) ) )
182 $redirect_url = get_permalink($wp_query->get_queried_object_id());
186 if ( is_singular() && get_query_var('page') && $redirect_url ) {
187 $redirect_url = trailingslashit( $redirect_url ) . user_trailingslashit( get_query_var( 'page' ), 'single_paged' );
188 $redirect['query'] = remove_query_arg( 'page', $redirect['query'] );
192 if ( get_query_var('paged') || is_feed() || get_query_var('cpage') ) {
193 if ( !$redirect_url )
194 $redirect_url = $requested_url;
195 $paged_redirect = @parse_url($redirect_url);
196 while ( preg_match( '#/page/?[0-9]+?(/+)?$#', $paged_redirect['path'] ) || preg_match( '#/(comments/?)?(feed|rss|rdf|atom|rss2)(/+)?$#', $paged_redirect['path'] ) || preg_match( '#/comment-page-[0-9]+(/+)?$#', $paged_redirect['path'] ) ) {
197 // Strip off paging and feed
198 $paged_redirect['path'] = preg_replace('#/page/?[0-9]+?(/+)?$#', '/', $paged_redirect['path']); // strip off any existing paging
199 $paged_redirect['path'] = preg_replace('#/(comments/?)?(feed|rss2?|rdf|atom)(/+|$)#', '/', $paged_redirect['path']); // strip off feed endings
200 $paged_redirect['path'] = preg_replace('#/comment-page-[0-9]+?(/+)?$#', '/', $paged_redirect['path']); // strip off any existing comment paging
205 $addl_path = !empty( $addl_path ) ? trailingslashit($addl_path) : '';
206 if ( get_query_var( 'withcomments' ) )
207 $addl_path .= 'comments/';
208 $addl_path .= user_trailingslashit( 'feed/' . ( ( get_default_feed() == get_query_var('feed') || 'feed' == get_query_var('feed') ) ? '' : get_query_var('feed') ), 'feed' );
209 $redirect['query'] = remove_query_arg( 'feed', $redirect['query'] );
212 if ( get_query_var('paged') > 0 ) {
213 $paged = get_query_var('paged');
214 $redirect['query'] = remove_query_arg( 'paged', $redirect['query'] );
216 if ( $paged > 1 && !is_single() ) {
217 $addl_path = ( !empty( $addl_path ) ? trailingslashit($addl_path) : '' ) . user_trailingslashit("page/$paged", 'paged');
218 } elseif ( !is_single() ) {
219 $addl_path = !empty( $addl_path ) ? trailingslashit($addl_path) : '';
221 } elseif ( $paged > 1 ) {
222 $redirect['query'] = add_query_arg( 'paged', $paged, $redirect['query'] );
226 if ( get_option('page_comments') && ( ( 'newest' == get_option('default_comments_page') && get_query_var('cpage') > 0 ) || ( 'newest' != get_option('default_comments_page') && get_query_var('cpage') > 1 ) ) ) {
227 $addl_path = ( !empty( $addl_path ) ? trailingslashit($addl_path) : '' ) . user_trailingslashit( 'comment-page-' . get_query_var('cpage'), 'commentpaged' );
228 $redirect['query'] = remove_query_arg( 'cpage', $redirect['query'] );
231 $paged_redirect['path'] = user_trailingslashit( preg_replace('|/index.php/?$|', '/', $paged_redirect['path']) ); // strip off trailing /index.php/
232 if ( !empty( $addl_path ) && $wp_rewrite->using_index_permalinks() && strpos($paged_redirect['path'], '/index.php/') === false )
233 $paged_redirect['path'] = trailingslashit($paged_redirect['path']) . 'index.php/';
234 if ( !empty( $addl_path ) )
235 $paged_redirect['path'] = trailingslashit($paged_redirect['path']) . $addl_path;
236 $redirect_url = $paged_redirect['scheme'] . '://' . $paged_redirect['host'] . $paged_redirect['path'];
237 $redirect['path'] = $paged_redirect['path'];
241 // tack on any additional query vars
242 $redirect['query'] = preg_replace( '#^\??&*?#', '', $redirect['query'] );
243 if ( $redirect_url && !empty($redirect['query']) ) {
244 if ( strpos($redirect_url, '?') !== false )
245 $redirect_url .= '&';
247 $redirect_url .= '?';
248 $redirect_url .= $redirect['query'];
252 $redirect = @parse_url($redirect_url);
254 // www.example.com vs example.com
255 $user_home = @parse_url(home_url());
256 if ( !empty($user_home['host']) )
257 $redirect['host'] = $user_home['host'];
258 if ( empty($user_home['path']) )
259 $user_home['path'] = '/';
262 if ( !empty($user_home['port']) )
263 $redirect['port'] = $user_home['port'];
265 unset($redirect['port']);
267 // trailing /index.php
268 $redirect['path'] = preg_replace('|/index.php/*?$|', '/', $redirect['path']);
270 // Remove trailing spaces from the path
271 $redirect['path'] = preg_replace( '#(%20| )+$#', '', $redirect['path'] );
273 if ( !empty( $redirect['query'] ) ) {
274 // Remove trailing spaces from certain terminating query string args
275 $redirect['query'] = preg_replace( '#((p|page_id|cat|tag)=[^&]*?)(%20| )+$#', '$1', $redirect['query'] );
277 // Clean up empty query strings
278 $redirect['query'] = trim(preg_replace( '#(^|&)(p|page_id|cat|tag)=?(&|$)#', '&', $redirect['query']), '&');
280 // Remove redundant leading ampersands
281 $redirect['query'] = preg_replace( '#^\??&*?#', '', $redirect['query'] );
284 // strip /index.php/ when we're not using PATHINFO permalinks
285 if ( !$wp_rewrite->using_index_permalinks() )
286 $redirect['path'] = str_replace('/index.php/', '/', $redirect['path']);
289 if ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() && !is_404() && (!is_front_page() || ( is_front_page() && (get_query_var('paged') > 1) ) ) ) {
291 if ( get_query_var('paged') > 0 ) {
292 $user_ts_type = 'paged';
294 foreach ( array('single', 'category', 'page', 'day', 'month', 'year', 'home') as $type ) {
295 $func = 'is_' . $type;
296 if ( call_user_func($func) ) {
297 $user_ts_type = $type;
302 $redirect['path'] = user_trailingslashit($redirect['path'], $user_ts_type);
303 } elseif ( is_front_page() ) {
304 $redirect['path'] = trailingslashit($redirect['path']);
307 // Strip multiple slashes out of the URL
308 if ( strpos($redirect['path'], '//') > -1 )
309 $redirect['path'] = preg_replace('|/+|', '/', $redirect['path']);
311 // Always trailing slash the Front Page URL
312 if ( trailingslashit( $redirect['path'] ) == trailingslashit( $user_home['path'] ) )
313 $redirect['path'] = trailingslashit($redirect['path']);
315 // Ignore differences in host capitalization, as this can lead to infinite redirects
316 // Only redirect no-www <=> yes-www
317 if ( strtolower($original['host']) == strtolower($redirect['host']) ||
318 ( strtolower($original['host']) != 'www.' . strtolower($redirect['host']) && 'www.' . strtolower($original['host']) != strtolower($redirect['host']) ) )
319 $redirect['host'] = $original['host'];
321 $compare_original = array($original['host'], $original['path']);
323 if ( !empty( $original['port'] ) )
324 $compare_original[] = $original['port'];
326 if ( !empty( $original['query'] ) )
327 $compare_original[] = $original['query'];
329 $compare_redirect = array($redirect['host'], $redirect['path']);
331 if ( !empty( $redirect['port'] ) )
332 $compare_redirect[] = $redirect['port'];
334 if ( !empty( $redirect['query'] ) )
335 $compare_redirect[] = $redirect['query'];
337 if ( $compare_original !== $compare_redirect ) {
338 $redirect_url = $redirect['scheme'] . '://' . $redirect['host'];
339 if ( !empty($redirect['port']) )
340 $redirect_url .= ':' . $redirect['port'];
341 $redirect_url .= $redirect['path'];
342 if ( !empty($redirect['query']) )
343 $redirect_url .= '?' . $redirect['query'];
346 if ( !$redirect_url || $redirect_url == $requested_url )
349 // Hex encoded octets are case-insensitive.
350 if ( false !== strpos($requested_url, '%') ) {
351 if ( !function_exists('lowercase_octets') ) {
352 function lowercase_octets($matches) {
353 return strtolower( $matches[0] );
356 $requested_url = preg_replace_callback('|%[a-fA-F0-9][a-fA-F0-9]|', 'lowercase_octets', $requested_url);
359 // Note that you can use the "redirect_canonical" filter to cancel a canonical redirect for whatever reason by returning FALSE
360 $redirect_url = apply_filters('redirect_canonical', $redirect_url, $requested_url);
362 if ( !$redirect_url || $redirect_url == $requested_url ) // yes, again -- in case the filter aborted the request
365 if ( $do_redirect ) {
366 // protect against chained redirects
367 if ( !redirect_canonical($redirect_url, false) ) {
368 wp_redirect($redirect_url, 301);
372 // die("1: $redirect_url<br />2: " . redirect_canonical( $redirect_url, false ) );
376 return $redirect_url;
381 * Attempts to guess correct post based on query vars.
386 * @return bool|string Returns False, if it can't find post, returns correct
387 * location on success.
389 function redirect_guess_404_permalink() {
392 if ( !get_query_var('name') )
395 $where = $wpdb->prepare("post_name LIKE %s", get_query_var('name') . '%');
397 // if any of post_type, year, monthnum, or day are set, use them to refine the query
398 if ( get_query_var('post_type') )
399 $where .= $wpdb->prepare(" AND post_type = %s", get_query_var('post_type'));
400 if ( get_query_var('year') )
401 $where .= $wpdb->prepare(" AND YEAR(post_date) = %d", get_query_var('year'));
402 if ( get_query_var('monthnum') )
403 $where .= $wpdb->prepare(" AND MONTH(post_date) = %d", get_query_var('monthnum'));
404 if ( get_query_var('day') )
405 $where .= $wpdb->prepare(" AND DAYOFMONTH(post_date) = %d", get_query_var('day'));
407 $post_id = $wpdb->get_var("SELECT ID FROM $wpdb->posts WHERE $where AND post_status = 'publish'");
410 return get_permalink($post_id);
413 add_action('template_redirect', 'redirect_canonical');