WordPress 4.2
[autoinstalls/wordpress.git] / wp-includes / canonical.php
1 <?php
2 /**
3  * Canonical API to handle WordPress Redirecting
4  *
5  * Based on "Permalink Redirect" from Scott Yang and "Enforce www. Preference"
6  * by Mark Jaquith
7  *
8  * @package WordPress
9  * @since 2.3.0
10  */
11
12 /**
13  * Redirects incoming links to the proper URL based on the site url.
14  *
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 penalty for duplicate content by redirecting all incoming links to
18  * one or the other.
19  *
20  * Prevents redirection for feeds, trackbacks, searches, comment popup, and
21  * admin URLs. Does not redirect on non-pretty-permalink-supporting IIS 7+,
22  * page/post previews, WP admin, Trackbacks, robots.txt, searches, or on POST
23  * requests.
24  *
25  * Will also attempt to find the correct link when a user enters a URL that does
26  * not exist based on exact WordPress query. Will instead try to parse the URL
27  * or query in an attempt to figure the correct page to go to.
28  *
29  * @since 2.3.0
30  * @uses $wp_rewrite
31  * @uses $is_IIS
32  *
33  * @param string $requested_url Optional. The URL that was requested, used to
34  *              figure if redirect is needed.
35  * @param bool $do_redirect Optional. Redirect to the new URL.
36  * @return null|false|string Null, if redirect not needed. False, if redirect
37  *              not needed or the string of the URL
38  */
39 function redirect_canonical( $requested_url = null, $do_redirect = true ) {
40         global $wp_rewrite, $is_IIS, $wp_query, $wpdb;
41
42         if ( isset( $_SERVER['REQUEST_METHOD'] ) && ! in_array( strtoupper( $_SERVER['REQUEST_METHOD'] ), array( 'GET', 'HEAD' ) ) ) {
43                 return;
44         }
45
46         // If we're not in wp-admin and the post has been published and preview nonce
47         // is non-existent or invalid then no need for preview in query
48         if ( is_preview() && get_query_var( 'p' ) && 'publish' == get_post_status( get_query_var( 'p' ) ) ) {
49                 if ( ! isset( $_GET['preview_id'] )
50                         || ! isset( $_GET['preview_nonce'] )
51                         || ! wp_verify_nonce( $_GET['preview_nonce'], 'post_preview_' . (int) $_GET['preview_id'] ) ) {
52                         $wp_query->is_preview = false;
53                 }
54         }
55
56         if ( is_trackback() || is_search() || is_comments_popup() || is_admin() || is_preview() || is_robots() || ( $is_IIS && !iis7_supports_permalinks() ) ) {
57                 return;
58         }
59
60         if ( !$requested_url ) {
61                 // build the URL in the address bar
62                 $requested_url  = is_ssl() ? 'https://' : 'http://';
63                 $requested_url .= $_SERVER['HTTP_HOST'];
64                 $requested_url .= $_SERVER['REQUEST_URI'];
65         }
66
67         $original = @parse_url($requested_url);
68         if ( false === $original )
69                 return;
70
71         // Some PHP setups turn requests for / into /index.php in REQUEST_URI
72         // See: https://core.trac.wordpress.org/ticket/5017
73         // See: https://core.trac.wordpress.org/ticket/7173
74         // Disabled, for now:
75         // $original['path'] = preg_replace('|/index\.php$|', '/', $original['path']);
76
77         $redirect = $original;
78         $redirect_url = false;
79
80         // Notice fixing
81         if ( !isset($redirect['path']) )
82                 $redirect['path'] = '';
83         if ( !isset($redirect['query']) )
84                 $redirect['query'] = '';
85
86         // If the original URL ended with non-breaking spaces, they were almost
87         // certainly inserted by accident. Let's remove them, so the reader doesn't
88         // see a 404 error with no obvious cause.
89         $redirect['path'] = preg_replace( '|(%C2%A0)+$|i', '', $redirect['path'] );
90
91         // It's not a preview, so remove it from URL
92         if ( get_query_var( 'preview' ) ) {
93                 $redirect['query'] = remove_query_arg( 'preview', $redirect['query'] );
94         }
95
96         if ( is_feed() && ( $id = get_query_var( 'p' ) ) ) {
97                 if ( $redirect_url = get_post_comments_feed_link( $id, get_query_var( 'feed' ) ) ) {
98                         $redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type', 'feed'), $redirect_url );
99                         $redirect['path'] = parse_url( $redirect_url, PHP_URL_PATH );
100                 }
101         }
102
103         if ( is_singular() && 1 > $wp_query->post_count && ($id = get_query_var('p')) ) {
104
105                 $vars = $wpdb->get_results( $wpdb->prepare("SELECT post_type, post_parent FROM $wpdb->posts WHERE ID = %d", $id) );
106
107                 if ( isset($vars[0]) && $vars = $vars[0] ) {
108                         if ( 'revision' == $vars->post_type && $vars->post_parent > 0 )
109                                 $id = $vars->post_parent;
110
111                         if ( $redirect_url = get_permalink($id) )
112                                 $redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ), $redirect_url );
113                 }
114         }
115
116         // These tests give us a WP-generated permalink
117         if ( is_404() ) {
118
119                 // Redirect ?page_id, ?p=, ?attachment_id= to their respective url's
120                 $id = max( get_query_var('p'), get_query_var('page_id'), get_query_var('attachment_id') );
121                 if ( $id && $redirect_post = get_post($id) ) {
122                         $post_type_obj = get_post_type_object($redirect_post->post_type);
123                         if ( $post_type_obj->public ) {
124                                 $redirect_url = get_permalink($redirect_post);
125                                 $redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ), $redirect_url );
126                         }
127                 }
128
129                 if ( get_query_var( 'day' ) && get_query_var( 'monthnum' ) && get_query_var( 'year' ) ) {
130                         $year  = get_query_var( 'year' );
131                         $month = get_query_var( 'monthnum' );
132                         $day   = get_query_var( 'day' );
133                         $date  = sprintf( '%04d-%02d-%02d', $year, $month, $day );
134                         if ( ! wp_checkdate( $month, $day, $year, $date ) ) {
135                                 $redirect_url = get_month_link( $year, $month );
136                                 $redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'year', 'monthnum', 'day' ), $redirect_url );
137                         }
138                 } elseif ( get_query_var( 'monthnum' ) && get_query_var( 'year' ) && 12 < get_query_var( 'monthnum' ) ) {
139                         $redirect_url = get_year_link( get_query_var( 'year' ) );
140                         $redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'year', 'monthnum' ), $redirect_url );
141                 }
142
143                 if ( ! $redirect_url ) {
144                         if ( $redirect_url = redirect_guess_404_permalink() ) {
145                                 $redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'page', 'feed', 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ), $redirect_url );
146                         }
147                 }
148
149         } elseif ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() ) {
150                 // rewriting of old ?p=X, ?m=2004, ?m=200401, ?m=20040101
151                 if ( is_attachment() && !empty($_GET['attachment_id']) && ! $redirect_url ) {
152                         if ( $redirect_url = get_attachment_link(get_query_var('attachment_id')) )
153                                 $redirect['query'] = remove_query_arg('attachment_id', $redirect['query']);
154                 } elseif ( is_single() && !empty($_GET['p']) && ! $redirect_url ) {
155                         if ( $redirect_url = get_permalink(get_query_var('p')) )
156                                 $redirect['query'] = remove_query_arg(array('p', 'post_type'), $redirect['query']);
157                 } elseif ( is_single() && !empty($_GET['name'])  && ! $redirect_url ) {
158                         if ( $redirect_url = get_permalink( $wp_query->get_queried_object_id() ) )
159                                 $redirect['query'] = remove_query_arg('name', $redirect['query']);
160                 } elseif ( is_page() && !empty($_GET['page_id']) && ! $redirect_url ) {
161                         if ( $redirect_url = get_permalink(get_query_var('page_id')) )
162                                 $redirect['query'] = remove_query_arg('page_id', $redirect['query']);
163                 } elseif ( is_page() && !is_feed() && isset($wp_query->queried_object) && 'page' == get_option('show_on_front') && $wp_query->queried_object->ID == get_option('page_on_front')  && ! $redirect_url ) {
164                         $redirect_url = home_url('/');
165                 } elseif ( is_home() && !empty($_GET['page_id']) && 'page' == get_option('show_on_front') && get_query_var('page_id') == get_option('page_for_posts')  && ! $redirect_url ) {
166                         if ( $redirect_url = get_permalink(get_option('page_for_posts')) )
167                                 $redirect['query'] = remove_query_arg('page_id', $redirect['query']);
168                 } elseif ( !empty($_GET['m']) && ( is_year() || is_month() || is_day() ) ) {
169                         $m = get_query_var('m');
170                         switch ( strlen($m) ) {
171                                 case 4: // Yearly
172                                         $redirect_url = get_year_link($m);
173                                         break;
174                                 case 6: // Monthly
175                                         $redirect_url = get_month_link( substr($m, 0, 4), substr($m, 4, 2) );
176                                         break;
177                                 case 8: // Daily
178                                         $redirect_url = get_day_link(substr($m, 0, 4), substr($m, 4, 2), substr($m, 6, 2));
179                                         break;
180                         }
181                         if ( $redirect_url )
182                                 $redirect['query'] = remove_query_arg('m', $redirect['query']);
183                 // now moving on to non ?m=X year/month/day links
184                 } elseif ( is_day() && get_query_var('year') && get_query_var('monthnum') && !empty($_GET['day']) ) {
185                         if ( $redirect_url = get_day_link(get_query_var('year'), get_query_var('monthnum'), get_query_var('day')) )
186                                 $redirect['query'] = remove_query_arg(array('year', 'monthnum', 'day'), $redirect['query']);
187                 } elseif ( is_month() && get_query_var('year') && !empty($_GET['monthnum']) ) {
188                         if ( $redirect_url = get_month_link(get_query_var('year'), get_query_var('monthnum')) )
189                                 $redirect['query'] = remove_query_arg(array('year', 'monthnum'), $redirect['query']);
190                 } elseif ( is_year() && !empty($_GET['year']) ) {
191                         if ( $redirect_url = get_year_link(get_query_var('year')) )
192                                 $redirect['query'] = remove_query_arg('year', $redirect['query']);
193                 } elseif ( is_author() && !empty($_GET['author']) && preg_match( '|^[0-9]+$|', $_GET['author'] ) ) {
194                         $author = get_userdata(get_query_var('author'));
195                         if ( ( false !== $author ) && $wpdb->get_var( $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE $wpdb->posts.post_author = %d AND $wpdb->posts.post_status = 'publish' LIMIT 1", $author->ID ) ) ) {
196                                 if ( $redirect_url = get_author_posts_url($author->ID, $author->user_nicename) )
197                                         $redirect['query'] = remove_query_arg('author', $redirect['query']);
198                         }
199                 } elseif ( is_category() || is_tag() || is_tax() ) { // Terms (Tags/categories)
200
201                         $term_count = 0;
202                         foreach ( $wp_query->tax_query->queried_terms as $tax_query )
203                                 $term_count += count( $tax_query['terms'] );
204
205                         $obj = $wp_query->get_queried_object();
206                         if ( $term_count <= 1 && !empty($obj->term_id) && ( $tax_url = get_term_link((int)$obj->term_id, $obj->taxonomy) ) && !is_wp_error($tax_url) ) {
207                                 if ( !empty($redirect['query']) ) {
208                                         // Strip taxonomy query vars off the url.
209                                         $qv_remove = array( 'term', 'taxonomy');
210                                         if ( is_category() ) {
211                                                 $qv_remove[] = 'category_name';
212                                                 $qv_remove[] = 'cat';
213                                         } elseif ( is_tag() ) {
214                                                 $qv_remove[] = 'tag';
215                                                 $qv_remove[] = 'tag_id';
216                                         } else { // Custom taxonomies will have a custom query var, remove those too:
217                                                 $tax_obj = get_taxonomy( $obj->taxonomy );
218                                                 if ( false !== $tax_obj->query_var )
219                                                         $qv_remove[] = $tax_obj->query_var;
220                                         }
221
222                                         $rewrite_vars = array_diff( array_keys($wp_query->query), array_keys($_GET) );
223
224                                         if ( !array_diff($rewrite_vars, array_keys($_GET))  ) { // Check to see if all the Query vars are coming from the rewrite, none are set via $_GET
225                                                 $redirect['query'] = remove_query_arg($qv_remove, $redirect['query']); //Remove all of the per-tax qv's
226
227                                                 // Create the destination url for this taxonomy
228                                                 $tax_url = parse_url($tax_url);
229                                                 if ( ! empty($tax_url['query']) ) { // Taxonomy accessible via ?taxonomy=..&term=.. or any custom qv..
230                                                         parse_str($tax_url['query'], $query_vars);
231                                                         $redirect['query'] = add_query_arg($query_vars, $redirect['query']);
232                                                 } else { // Taxonomy is accessible via a "pretty-URL"
233                                                         $redirect['path'] = $tax_url['path'];
234                                                 }
235
236                                         } else { // Some query vars are set via $_GET. Unset those from $_GET that exist via the rewrite
237                                                 foreach ( $qv_remove as $_qv ) {
238                                                         if ( isset($rewrite_vars[$_qv]) )
239                                                                 $redirect['query'] = remove_query_arg($_qv, $redirect['query']);
240                                                 }
241                                         }
242                                 }
243
244                         }
245                 } elseif ( is_single() && strpos($wp_rewrite->permalink_structure, '%category%') !== false && $cat = get_query_var( 'category_name' ) ) {
246                         $category = get_category_by_path( $cat );
247                         $post_terms = wp_get_object_terms($wp_query->get_queried_object_id(), 'category', array('fields' => 'tt_ids'));
248                         if ( (!$category || is_wp_error($category)) || ( !is_wp_error($post_terms) && !empty($post_terms) && !in_array($category->term_taxonomy_id, $post_terms) ) )
249                                 $redirect_url = get_permalink($wp_query->get_queried_object_id());
250                 }
251
252                 // Post Paging
253                 if ( is_singular() && ! is_front_page() && get_query_var('page') ) {
254                         if ( !$redirect_url )
255                                 $redirect_url = get_permalink( get_queried_object_id() );
256                         $redirect_url = trailingslashit( $redirect_url ) . user_trailingslashit( get_query_var( 'page' ), 'single_paged' );
257                         $redirect['query'] = remove_query_arg( 'page', $redirect['query'] );
258                 }
259
260                 // paging and feeds
261                 if ( get_query_var('paged') || is_feed() || get_query_var('cpage') ) {
262                         while ( preg_match( "#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", $redirect['path'] ) || preg_match( '#/(comments/?)?(feed|rss|rdf|atom|rss2)(/+)?$#', $redirect['path'] ) || preg_match( "#/{$wp_rewrite->comments_pagination_base}-[0-9]+(/+)?$#", $redirect['path'] ) ) {
263                                 // Strip off paging and feed
264                                 $redirect['path'] = preg_replace("#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", '/', $redirect['path']); // strip off any existing paging
265                                 $redirect['path'] = preg_replace('#/(comments/?)?(feed|rss2?|rdf|atom)(/+|$)#', '/', $redirect['path']); // strip off feed endings
266                                 $redirect['path'] = preg_replace("#/{$wp_rewrite->comments_pagination_base}-[0-9]+?(/+)?$#", '/', $redirect['path']); // strip off any existing comment paging
267                         }
268
269                         $addl_path = '';
270                         if ( is_feed() && in_array( get_query_var('feed'), $wp_rewrite->feeds ) ) {
271                                 $addl_path = !empty( $addl_path ) ? trailingslashit($addl_path) : '';
272                                 if ( !is_singular() && get_query_var( 'withcomments' ) )
273                                         $addl_path .= 'comments/';
274                                 if ( ( 'rss' == get_default_feed() && 'feed' == get_query_var('feed') ) || 'rss' == get_query_var('feed') )
275                                         $addl_path .= user_trailingslashit( 'feed/' . ( ( get_default_feed() == 'rss2' ) ? '' : 'rss2' ), 'feed' );
276                                 else
277                                         $addl_path .= user_trailingslashit( 'feed/' . ( ( get_default_feed() ==  get_query_var('feed') || 'feed' == get_query_var('feed') ) ? '' : get_query_var('feed') ), 'feed' );
278                                 $redirect['query'] = remove_query_arg( 'feed', $redirect['query'] );
279                         } elseif ( is_feed() && 'old' == get_query_var('feed') ) {
280                                 $old_feed_files = array(
281                                         'wp-atom.php'         => 'atom',
282                                         'wp-commentsrss2.php' => 'comments_rss2',
283                                         'wp-feed.php'         => get_default_feed(),
284                                         'wp-rdf.php'          => 'rdf',
285                                         'wp-rss.php'          => 'rss2',
286                                         'wp-rss2.php'         => 'rss2',
287                                 );
288                                 if ( isset( $old_feed_files[ basename( $redirect['path'] ) ] ) ) {
289                                         $redirect_url = get_feed_link( $old_feed_files[ basename( $redirect['path'] ) ] );
290                                         wp_redirect( $redirect_url, 301 );
291                                         die();
292                                 }
293                         }
294
295                         if ( get_query_var('paged') > 0 ) {
296                                 $paged = get_query_var('paged');
297                                 $redirect['query'] = remove_query_arg( 'paged', $redirect['query'] );
298                                 if ( !is_feed() ) {
299                                         if ( $paged > 1 && !is_single() ) {
300                                                 $addl_path = ( !empty( $addl_path ) ? trailingslashit($addl_path) : '' ) . user_trailingslashit("$wp_rewrite->pagination_base/$paged", 'paged');
301                                         } elseif ( !is_single() ) {
302                                                 $addl_path = !empty( $addl_path ) ? trailingslashit($addl_path) : '';
303                                         }
304                                 } elseif ( $paged > 1 ) {
305                                         $redirect['query'] = add_query_arg( 'paged', $paged, $redirect['query'] );
306                                 }
307                         }
308
309                         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 ) ) ) {
310                                 $addl_path = ( !empty( $addl_path ) ? trailingslashit($addl_path) : '' ) . user_trailingslashit( $wp_rewrite->comments_pagination_base . '-' . get_query_var('cpage'), 'commentpaged' );
311                                 $redirect['query'] = remove_query_arg( 'cpage', $redirect['query'] );
312                         }
313
314                         $redirect['path'] = user_trailingslashit( preg_replace('|/' . preg_quote( $wp_rewrite->index, '|' ) . '/?$|', '/', $redirect['path']) ); // strip off trailing /index.php/
315                         if ( !empty( $addl_path ) && $wp_rewrite->using_index_permalinks() && strpos($redirect['path'], '/' . $wp_rewrite->index . '/') === false )
316                                 $redirect['path'] = trailingslashit($redirect['path']) . $wp_rewrite->index . '/';
317                         if ( !empty( $addl_path ) )
318                                 $redirect['path'] = trailingslashit($redirect['path']) . $addl_path;
319                         $redirect_url = $redirect['scheme'] . '://' . $redirect['host'] . $redirect['path'];
320                 }
321
322                 if ( 'wp-register.php' == basename( $redirect['path'] ) ) {
323                         if ( is_multisite() ) {
324                                 /** This filter is documented in wp-login.php */
325                                 $redirect_url = apply_filters( 'wp_signup_location', network_site_url( 'wp-signup.php' ) );
326                         } else {
327                                 $redirect_url = site_url( 'wp-login.php?action=register' );
328                         }
329
330                         wp_redirect( $redirect_url, 301 );
331                         die();
332                 }
333         }
334
335         // tack on any additional query vars
336         $redirect['query'] = preg_replace( '#^\??&*?#', '', $redirect['query'] );
337         if ( $redirect_url && !empty($redirect['query']) ) {
338                 parse_str( $redirect['query'], $_parsed_query );
339                 $redirect = @parse_url($redirect_url);
340
341                 if ( ! empty( $_parsed_query['name'] ) && ! empty( $redirect['query'] ) ) {
342                         parse_str( $redirect['query'], $_parsed_redirect_query );
343
344                         if ( empty( $_parsed_redirect_query['name'] ) )
345                                 unset( $_parsed_query['name'] );
346                 }
347
348                 $_parsed_query = rawurlencode_deep( $_parsed_query );
349                 $redirect_url = add_query_arg( $_parsed_query, $redirect_url );
350         }
351
352         if ( $redirect_url )
353                 $redirect = @parse_url($redirect_url);
354
355         // www.example.com vs example.com
356         $user_home = @parse_url(home_url());
357         if ( !empty($user_home['host']) )
358                 $redirect['host'] = $user_home['host'];
359         if ( empty($user_home['path']) )
360                 $user_home['path'] = '/';
361
362         // Handle ports
363         if ( !empty($user_home['port']) )
364                 $redirect['port'] = $user_home['port'];
365         else
366                 unset($redirect['port']);
367
368         // trailing /index.php
369         $redirect['path'] = preg_replace('|/' . preg_quote( $wp_rewrite->index, '|' ) . '/*?$|', '/', $redirect['path']);
370
371         // Remove trailing spaces from the path
372         $redirect['path'] = preg_replace( '#(%20| )+$#', '', $redirect['path'] );
373
374         if ( !empty( $redirect['query'] ) ) {
375                 // Remove trailing spaces from certain terminating query string args
376                 $redirect['query'] = preg_replace( '#((p|page_id|cat|tag)=[^&]*?)(%20| )+$#', '$1', $redirect['query'] );
377
378                 // Clean up empty query strings
379                 $redirect['query'] = trim(preg_replace( '#(^|&)(p|page_id|cat|tag)=?(&|$)#', '&', $redirect['query']), '&');
380
381                 // Redirect obsolete feeds
382                 $redirect['query'] = preg_replace( '#(^|&)feed=rss(&|$)#', '$1feed=rss2$2', $redirect['query'] );
383
384                 // Remove redundant leading ampersands
385                 $redirect['query'] = preg_replace( '#^\??&*?#', '', $redirect['query'] );
386         }
387
388         // strip /index.php/ when we're not using PATHINFO permalinks
389         if ( !$wp_rewrite->using_index_permalinks() )
390                 $redirect['path'] = str_replace( '/' . $wp_rewrite->index . '/', '/', $redirect['path'] );
391
392         // trailing slashes
393         if ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() && !is_404() && (!is_front_page() || ( is_front_page() && (get_query_var('paged') > 1) ) ) ) {
394                 $user_ts_type = '';
395                 if ( get_query_var('paged') > 0 ) {
396                         $user_ts_type = 'paged';
397                 } else {
398                         foreach ( array('single', 'category', 'page', 'day', 'month', 'year', 'home') as $type ) {
399                                 $func = 'is_' . $type;
400                                 if ( call_user_func($func) ) {
401                                         $user_ts_type = $type;
402                                         break;
403                                 }
404                         }
405                 }
406                 $redirect['path'] = user_trailingslashit($redirect['path'], $user_ts_type);
407         } elseif ( is_front_page() ) {
408                 $redirect['path'] = trailingslashit($redirect['path']);
409         }
410
411         // Strip multiple slashes out of the URL
412         if ( strpos($redirect['path'], '//') > -1 )
413                 $redirect['path'] = preg_replace('|/+|', '/', $redirect['path']);
414
415         // Always trailing slash the Front Page URL
416         if ( trailingslashit( $redirect['path'] ) == trailingslashit( $user_home['path'] ) )
417                 $redirect['path'] = trailingslashit($redirect['path']);
418
419         // Ignore differences in host capitalization, as this can lead to infinite redirects
420         // Only redirect no-www <=> yes-www
421         if ( strtolower($original['host']) == strtolower($redirect['host']) ||
422                 ( strtolower($original['host']) != 'www.' . strtolower($redirect['host']) && 'www.' . strtolower($original['host']) != strtolower($redirect['host']) ) )
423                 $redirect['host'] = $original['host'];
424
425         $compare_original = array( $original['host'], $original['path'] );
426
427         if ( !empty( $original['port'] ) )
428                 $compare_original[] = $original['port'];
429
430         if ( !empty( $original['query'] ) )
431                 $compare_original[] = $original['query'];
432
433         $compare_redirect = array( $redirect['host'], $redirect['path'] );
434
435         if ( !empty( $redirect['port'] ) )
436                 $compare_redirect[] = $redirect['port'];
437
438         if ( !empty( $redirect['query'] ) )
439                 $compare_redirect[] = $redirect['query'];
440
441         if ( $compare_original !== $compare_redirect ) {
442                 $redirect_url = $redirect['scheme'] . '://' . $redirect['host'];
443                 if ( !empty($redirect['port']) )
444                         $redirect_url .= ':' . $redirect['port'];
445                 $redirect_url .= $redirect['path'];
446                 if ( !empty($redirect['query']) )
447                         $redirect_url .= '?' . $redirect['query'];
448         }
449
450         if ( !$redirect_url || $redirect_url == $requested_url )
451                 return false;
452
453         // Hex encoded octets are case-insensitive.
454         if ( false !== strpos($requested_url, '%') ) {
455                 if ( !function_exists('lowercase_octets') ) {
456                         function lowercase_octets($matches) {
457                                 return strtolower( $matches[0] );
458                         }
459                 }
460                 $requested_url = preg_replace_callback('|%[a-fA-F0-9][a-fA-F0-9]|', 'lowercase_octets', $requested_url);
461         }
462
463         /**
464          * Filter the canonical redirect URL.
465          *
466          * Returning false to this filter will cancel the redirect.
467          *
468          * @since 2.3.0
469          *
470          * @param string $redirect_url  The redirect URL.
471          * @param string $requested_url The requested URL.
472          */
473         $redirect_url = apply_filters( 'redirect_canonical', $redirect_url, $requested_url );
474
475         if ( !$redirect_url || $redirect_url == $requested_url ) // yes, again -- in case the filter aborted the request
476                 return false;
477
478         if ( $do_redirect ) {
479                 // protect against chained redirects
480                 if ( !redirect_canonical($redirect_url, false) ) {
481                         wp_redirect($redirect_url, 301);
482                         exit();
483                 } else {
484                         // Debug
485                         // die("1: $redirect_url<br />2: " . redirect_canonical( $redirect_url, false ) );
486                         return false;
487                 }
488         } else {
489                 return $redirect_url;
490         }
491 }
492
493 /**
494  * Removes arguments from a query string if they are not present in a URL
495  * DO NOT use this in plugin code.
496  *
497  * @since 3.4.0
498  * @access private
499  *
500  * @param string $query_string
501  * @param array $args_to_check
502  * @param string $url
503  * @return string The altered query string
504  */
505 function _remove_qs_args_if_not_in_url( $query_string, Array $args_to_check, $url ) {
506         $parsed_url = @parse_url( $url );
507         if ( ! empty( $parsed_url['query'] ) ) {
508                 parse_str( $parsed_url['query'], $parsed_query );
509                 foreach ( $args_to_check as $qv ) {
510                         if ( !isset( $parsed_query[$qv] ) )
511                                 $query_string = remove_query_arg( $qv, $query_string );
512                 }
513         } else {
514                 $query_string = remove_query_arg( $args_to_check, $query_string );
515         }
516         return $query_string;
517 }
518
519 /**
520  * Attempts to guess the correct URL based on query vars
521  *
522  * @since 2.3.0
523  *
524  * @global wpdb $wpdb WordPress database abstraction object.
525  *
526  * @return bool|string The correct URL if one is found. False on failure.
527  */
528 function redirect_guess_404_permalink() {
529         global $wpdb, $wp_rewrite;
530
531         if ( get_query_var('name') ) {
532                 $where = $wpdb->prepare("post_name LIKE %s", $wpdb->esc_like( get_query_var('name') ) . '%');
533
534                 // if any of post_type, year, monthnum, or day are set, use them to refine the query
535                 if ( get_query_var('post_type') )
536                         $where .= $wpdb->prepare(" AND post_type = %s", get_query_var('post_type'));
537                 else
538                         $where .= " AND post_type IN ('" . implode( "', '", get_post_types( array( 'public' => true ) ) ) . "')";
539
540                 if ( get_query_var('year') )
541                         $where .= $wpdb->prepare(" AND YEAR(post_date) = %d", get_query_var('year'));
542                 if ( get_query_var('monthnum') )
543                         $where .= $wpdb->prepare(" AND MONTH(post_date) = %d", get_query_var('monthnum'));
544                 if ( get_query_var('day') )
545                         $where .= $wpdb->prepare(" AND DAYOFMONTH(post_date) = %d", get_query_var('day'));
546
547                 $post_id = $wpdb->get_var("SELECT ID FROM $wpdb->posts WHERE $where AND post_status = 'publish'");
548                 if ( ! $post_id )
549                         return false;
550                 if ( get_query_var( 'feed' ) )
551                         return get_post_comments_feed_link( $post_id, get_query_var( 'feed' ) );
552                 elseif ( get_query_var( 'page' ) )
553                         return trailingslashit( get_permalink( $post_id ) ) . user_trailingslashit( get_query_var( 'page' ), 'single_paged' );
554                 else
555                         return get_permalink( $post_id );
556         }
557
558         return false;
559 }
560
561 function wp_redirect_admin_locations() {
562         global $wp_rewrite;
563         if ( ! ( is_404() && $wp_rewrite->using_permalinks() ) )
564                 return;
565
566         $admins = array(
567                 home_url( 'wp-admin', 'relative' ),
568                 home_url( 'dashboard', 'relative' ),
569                 home_url( 'admin', 'relative' ),
570                 site_url( 'dashboard', 'relative' ),
571                 site_url( 'admin', 'relative' ),
572         );
573         if ( in_array( untrailingslashit( $_SERVER['REQUEST_URI'] ), $admins ) ) {
574                 wp_redirect( admin_url() );
575                 exit;
576         }
577
578         $logins = array(
579                 home_url( 'wp-login.php', 'relative' ),
580                 home_url( 'login', 'relative' ),
581                 site_url( 'login', 'relative' ),
582         );
583         if ( in_array( untrailingslashit( $_SERVER['REQUEST_URI'] ), $logins ) ) {
584                 wp_redirect( site_url( 'wp-login.php', 'login' ) );
585                 exit;
586         }
587 }