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   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 penality 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 IIS, page/post previews, and on form data.
  22   *
  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.
  26   *
  27   * @since 2.3.0
  28   * @uses $wp_rewrite
  29   * @uses $is_IIS
  30   *
  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
  36   */
  37  function redirect_canonical( $requested_url = null, $do_redirect = true ) {
  38      global $wp_rewrite, $is_IIS, $wp_query, $wpdb;
  39  
  40      if ( is_trackback() || is_search() || is_comments_popup() || is_admin() || !empty($_POST) || is_preview() || is_robots() || $is_IIS )
  41          return;
  42  
  43      if ( !$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'];
  48      }
  49  
  50      $original = @parse_url($requested_url);
  51      if ( false === $original )
  52          return;
  53  
  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
  57      // Disabled, for now:
  58      // $original['path'] = preg_replace('|/index\.php$|', '/', $original['path']);
  59  
  60      $redirect = $original;
  61      $redirect_url = false;
  62  
  63      // Notice fixing
  64      if ( !isset($redirect['path']) )
  65          $redirect['path'] = '';
  66      if ( !isset($redirect['query']) )
  67          $redirect['query'] = '';
  68  
  69      if ( is_singular() && 1 > $wp_query->post_count && ($id = get_query_var('p')) ) {
  70  
  71          $vars = $wpdb->get_results( $wpdb->prepare("SELECT post_type, post_parent FROM $wpdb->posts WHERE ID = %d", $id) );
  72  
  73          if ( isset($vars[0]) && $vars = $vars[0] ) {
  74              if ( 'revision' == $vars->post_type && $vars->post_parent > 0 )
  75                  $id = $vars->post_parent;
  76  
  77              if ( $redirect_url = get_permalink($id) )
  78                  $redirect['query'] = remove_query_arg(array('p', 'page_id', 'attachment_id', 'post_type'), $redirect['query']);
  79          }
  80      }
  81  
  82      // These tests give us a WP-generated permalink
  83      if ( is_404() ) {
  84  
  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']);
  92              }
  93          }
  94  
  95          if ( ! $redirect_url )
  96              $redirect_url = redirect_guess_404_permalink();
  97  
  98      } elseif ( is_object($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) ) {
 120                  case 4: // Yearly
 121                      $redirect_url = get_year_link($m);
 122                      break;
 123                  case 6: // Monthly
 124                      $redirect_url = get_month_link( substr($m, 0, 4), substr($m, 4, 2) );
 125                      break;
 126                  case 8: // Daily
 127                      $redirect_url = get_day_link(substr($m, 0, 4), substr($m, 4, 2), substr($m, 6, 2));
 128                      break;
 129              }
 130              if ( $redirect_url )
 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 ) && $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 ) ) ) {
 145                  if ( $redirect_url = get_author_posts_url($author->ID, $author->user_nicename) )
 146                      $redirect['query'] = remove_query_arg('author', $redirect['query']);
 147              }
 148          } elseif ( is_category() || is_tag() || is_tax() ) { // Terms (Tags/categories)
 149  
 150              $term_count = 0;
 151              foreach ( $wp_query->tax_query->queries as $tax_query )
 152                  $term_count += count( $tax_query['terms'] );
 153  
 154              $obj = $wp_query->get_queried_object();
 155              if ( $term_count <= 1 && !empty($obj->term_id) && ( $tax_url = get_term_link((int)$obj->term_id, $obj->taxonomy) ) && !is_wp_error($tax_url) ) {
 156                  if ( !empty($redirect['query']) ) {
 157                      // Strip taxonomy query vars off the url.
 158                      $qv_remove = array( 'term', 'taxonomy');
 159                      if ( is_category() ) {
 160                          $qv_remove[] = 'category_name';
 161                          $qv_remove[] = 'cat';
 162                      } elseif ( is_tag() ) {
 163                          $qv_remove[] = 'tag';
 164                          $qv_remove[] = 'tag_id';
 165                      } else { // Custom taxonomies will have a custom query var, remove those too:
 166                          $tax_obj = get_taxonomy( $obj->taxonomy );
 167                          if ( false !== $tax_obj->query_var )
 168                              $qv_remove[] = $tax_obj->query_var;
 169                      }
 170  
 171                      $rewrite_vars = array_diff( array_keys($wp_query->query), array_keys($_GET) );
 172  
 173                      if ( !array_diff($rewrite_vars, array_keys($_GET))  ) { // Check to see if all the Query vars are coming from the rewrite, none are set via $_GET
 174                          $redirect['query'] = remove_query_arg($qv_remove, $redirect['query']); //Remove all of the per-tax qv's
 175  
 176                          // Create the destination url for this taxonomy
 177                          $tax_url = parse_url($tax_url);
 178                          if ( ! empty($tax_url['query']) ) { // Taxonomy accessable via ?taxonomy=..&term=.. or any custom qv..
 179                              parse_str($tax_url['query'], $query_vars);
 180                              $redirect['query'] = add_query_arg($query_vars, $redirect['query']);
 181                          } else { // Taxonomy is accessable via a "pretty-URL"
 182                              $redirect['path'] = $tax_url['path'];
 183                          }
 184  
 185                      } else { // Some query vars are set via $_GET. Unset those from $_GET that exist via the rewrite
 186                          foreach ( $qv_remove as $_qv ) {
 187                              if ( isset($rewrite_vars[$_qv]) ) 
 188                                  $redirect['query'] = remove_query_arg($_qv, $redirect['query']);
 189                          }
 190                      }
 191                  }
 192  
 193              }
 194          } elseif ( is_single() && strpos($wp_rewrite->permalink_structure, '%category%') !== false ) {
 195              $category = get_category_by_path(get_query_var('category_name'));
 196              $post_terms = wp_get_object_terms($wp_query->get_queried_object_id(), 'category', array('fields' => 'tt_ids'));
 197              if ( (!$category || is_wp_error($category)) || ( !is_wp_error($post_terms) && !empty($post_terms) && !in_array($category->term_taxonomy_id, $post_terms) ) )
 198                  $redirect_url = get_permalink($wp_query->get_queried_object_id());
 199          }
 200  
 201          // Post Paging
 202          if ( is_singular() && get_query_var('page') && $redirect_url ) {
 203              $redirect_url = trailingslashit( $redirect_url ) . user_trailingslashit( get_query_var( 'page' ), 'single_paged' );
 204              $redirect['query'] = remove_query_arg( 'page', $redirect['query'] );
 205          }
 206  
 207          // paging and feeds
 208          if ( get_query_var('paged') || is_feed() || get_query_var('cpage') ) {
 209              while ( preg_match( "#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", $redirect['path'] ) || preg_match( '#/(comments/?)?(feed|rss|rdf|atom|rss2)(/+)?$#', $redirect['path'] ) || preg_match( '#/comment-page-[0-9]+(/+)?$#', $redirect['path'] ) ) {
 210                  // Strip off paging and feed
 211                  $redirect['path'] = preg_replace("#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", '/', $redirect['path']); // strip off any existing paging
 212                  $redirect['path'] = preg_replace('#/(comments/?)?(feed|rss2?|rdf|atom)(/+|$)#', '/', $redirect['path']); // strip off feed endings
 213                  $redirect['path'] = preg_replace('#/comment-page-[0-9]+?(/+)?$#', '/', $redirect['path']); // strip off any existing comment paging
 214              }
 215  
 216              $addl_path = '';
 217              if ( is_feed() && in_array( get_query_var('feed'), $wp_rewrite->feeds ) ) {
 218                  $addl_path = !empty( $addl_path ) ? trailingslashit($addl_path) : '';
 219                  if ( get_query_var( 'withcomments' ) )
 220                      $addl_path .= 'comments/';
 221                  $addl_path .= user_trailingslashit( 'feed/' . ( ( get_default_feed() ==  get_query_var('feed') || 'feed' == get_query_var('feed') ) ? '' : get_query_var('feed') ), 'feed' );
 222                  $redirect['query'] = remove_query_arg( 'feed', $redirect['query'] );
 223              }
 224  
 225              if ( get_query_var('paged') > 0 ) {
 226                  $paged = get_query_var('paged');
 227                  $redirect['query'] = remove_query_arg( 'paged', $redirect['query'] );
 228                  if ( !is_feed() ) {
 229                      if ( $paged > 1 && !is_single() ) {
 230                          $addl_path = ( !empty( $addl_path ) ? trailingslashit($addl_path) : '' ) . user_trailingslashit("$wp_rewrite->pagination_base/$paged", 'paged');
 231                      } elseif ( !is_single() ) {
 232                          $addl_path = !empty( $addl_path ) ? trailingslashit($addl_path) : '';
 233                      }
 234                  } elseif ( $paged > 1 ) {
 235                      $redirect['query'] = add_query_arg( 'paged', $paged, $redirect['query'] );
 236                  }
 237              }
 238  
 239              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 ) ) ) {
 240                  $addl_path = ( !empty( $addl_path ) ? trailingslashit($addl_path) : '' ) . user_trailingslashit( 'comment-page-' . get_query_var('cpage'), 'commentpaged' );
 241                  $redirect['query'] = remove_query_arg( 'cpage', $redirect['query'] );
 242              }
 243  
 244              $redirect['path'] = user_trailingslashit( preg_replace('|/index.php/?$|', '/', $redirect['path']) ); // strip off trailing /index.php/
 245              if ( !empty( $addl_path ) && $wp_rewrite->using_index_permalinks() && strpos($redirect['path'], '/index.php/') === false )
 246                  $redirect['path'] = trailingslashit($redirect['path']) . 'index.php/';
 247              if ( !empty( $addl_path ) )
 248                  $redirect['path'] = trailingslashit($redirect['path']) . $addl_path;
 249              $redirect_url = $redirect['scheme'] . '://' . $redirect['host'] . $redirect['path'];
 250          }
 251      }
 252  
 253      // tack on any additional query vars
 254      $redirect['query'] = preg_replace( '#^\??&*?#', '', $redirect['query'] );
 255      if ( $redirect_url && !empty($redirect['query']) ) {
 256          parse_str( $redirect['query'], $_parsed_query );
 257          $redirect = @parse_url($redirect_url);
 258  
 259          if ( ! empty( $_parsed_query['name'] ) && ! empty( $redirect['query'] ) ) {
 260              parse_str( $redirect['query'], $_parsed_redirect_query );
 261  
 262              if ( empty( $_parsed_redirect_query['name'] ) )
 263                  unset( $_parsed_query['name'] );
 264          }
 265  
 266          $redirect_url = add_query_arg( $_parsed_query, $redirect_url );
 267      }
 268  
 269      if ( $redirect_url )
 270          $redirect = @parse_url($redirect_url);
 271  
 272      // www.example.com vs example.com
 273      $user_home = @parse_url(home_url());
 274      if ( !empty($user_home['host']) )
 275          $redirect['host'] = $user_home['host'];
 276      if ( empty($user_home['path']) )
 277          $user_home['path'] = '/';
 278  
 279      // Handle ports
 280      if ( !empty($user_home['port']) )
 281          $redirect['port'] = $user_home['port'];
 282      else
 283          unset($redirect['port']);
 284  
 285      // trailing /index.php
 286      $redirect['path'] = preg_replace('|/index.php/*?$|', '/', $redirect['path']);
 287  
 288      // Remove trailing spaces from the path
 289      $redirect['path'] = preg_replace( '#(%20| )+$#', '', $redirect['path'] );
 290  
 291      if ( !empty( $redirect['query'] ) ) {
 292          // Remove trailing spaces from certain terminating query string args
 293          $redirect['query'] = preg_replace( '#((p|page_id|cat|tag)=[^&]*?)(%20| )+$#', '$1', $redirect['query'] );
 294  
 295          // Clean up empty query strings
 296          $redirect['query'] = trim(preg_replace( '#(^|&)(p|page_id|cat|tag)=?(&|$)#', '&', $redirect['query']), '&');
 297  
 298          // Remove redundant leading ampersands
 299          $redirect['query'] = preg_replace( '#^\??&*?#', '', $redirect['query'] );
 300      }
 301  
 302      // strip /index.php/ when we're not using PATHINFO permalinks
 303      if ( !$wp_rewrite->using_index_permalinks() )
 304          $redirect['path'] = str_replace('/index.php/', '/', $redirect['path']);
 305  
 306      // trailing slashes
 307      if ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() && !is_404() && (!is_front_page() || ( is_front_page() && (get_query_var('paged') > 1) ) ) ) {
 308          $user_ts_type = '';
 309          if ( get_query_var('paged') > 0 ) {
 310              $user_ts_type = 'paged';
 311          } else {
 312              foreach ( array('single', 'category', 'page', 'day', 'month', 'year', 'home') as $type ) {
 313                  $func = 'is_' . $type;
 314                  if ( call_user_func($func) ) {
 315                      $user_ts_type = $type;
 316                      break;
 317                  }
 318              }
 319          }
 320          $redirect['path'] = user_trailingslashit($redirect['path'], $user_ts_type);
 321      } elseif ( is_front_page() ) {
 322          $redirect['path'] = trailingslashit($redirect['path']);
 323      }
 324  
 325      // Strip multiple slashes out of the URL
 326      if ( strpos($redirect['path'], '//') > -1 )
 327          $redirect['path'] = preg_replace('|/+|', '/', $redirect['path']);
 328  
 329      // Always trailing slash the Front Page URL
 330      if ( trailingslashit( $redirect['path'] ) == trailingslashit( $user_home['path'] ) )
 331          $redirect['path'] = trailingslashit($redirect['path']);
 332  
 333      // Ignore differences in host capitalization, as this can lead to infinite redirects
 334      // Only redirect no-www <=> yes-www
 335      if ( strtolower($original['host']) == strtolower($redirect['host']) ||
 336          ( strtolower($original['host']) != 'www.' . strtolower($redirect['host']) && 'www.' . strtolower($original['host']) != strtolower($redirect['host']) ) )
 337          $redirect['host'] = $original['host'];
 338  
 339      $compare_original = array($original['host'], $original['path']);
 340  
 341      if ( !empty( $original['port'] ) )
 342          $compare_original[] = $original['port'];
 343  
 344      if ( !empty( $original['query'] ) )
 345          $compare_original[] = $original['query'];
 346  
 347      $compare_redirect = array($redirect['host'], $redirect['path']);
 348  
 349      if ( !empty( $redirect['port'] ) )
 350          $compare_redirect[] = $redirect['port'];
 351  
 352      if ( !empty( $redirect['query'] ) )
 353          $compare_redirect[] = $redirect['query'];
 354  
 355      if ( $compare_original !== $compare_redirect ) {
 356          $redirect_url = $redirect['scheme'] . '://' . $redirect['host'];
 357          if ( !empty($redirect['port']) )
 358              $redirect_url .= ':' . $redirect['port'];
 359          $redirect_url .= $redirect['path'];
 360          if ( !empty($redirect['query']) )
 361              $redirect_url .= '?' . $redirect['query'];
 362      }
 363  
 364      if ( !$redirect_url || $redirect_url == $requested_url )
 365          return false;
 366  
 367      // Hex encoded octets are case-insensitive.
 368      if ( false !== strpos($requested_url, '%') ) {
 369          if ( !function_exists('lowercase_octets') ) {
 370              function lowercase_octets($matches) {
 371                  return strtolower( $matches[0] );
 372              }
 373          }
 374          $requested_url = preg_replace_callback('|%[a-fA-F0-9][a-fA-F0-9]|', 'lowercase_octets', $requested_url);
 375      }
 376  
 377      // Note that you can use the "redirect_canonical" filter to cancel a canonical redirect for whatever reason by returning FALSE
 378      $redirect_url = apply_filters('redirect_canonical', $redirect_url, $requested_url);
 379  
 380      if ( !$redirect_url || $redirect_url == $requested_url ) // yes, again -- in case the filter aborted the request
 381          return false;
 382  
 383      if ( $do_redirect ) {
 384          // protect against chained redirects
 385          if ( !redirect_canonical($redirect_url, false) ) {
 386              wp_redirect($redirect_url, 301);
 387              exit();
 388          } else {
 389              // Debug
 390              // die("1: $redirect_url<br />2: " . redirect_canonical( $redirect_url, false ) );
 391              return false;
 392          }
 393      } else {
 394          return $redirect_url;
 395      }
 396  }
 397  
 398  /**
 399   * Attempts to guess correct post based on query vars.
 400   *
 401   * @since 2.3.0
 402   * @uses $wpdb
 403   *
 404   * @return bool|string Returns False, if it can't find post, returns correct
 405   *        location on success.
 406   */
 407  function redirect_guess_404_permalink() {
 408      global $wpdb;
 409  
 410      if ( !get_query_var('name') )
 411          return false;
 412  
 413      $where = $wpdb->prepare("post_name LIKE %s", like_escape( get_query_var('name') ) . '%');
 414  
 415      // if any of post_type, year, monthnum, or day are set, use them to refine the query
 416      if ( get_query_var('post_type') )
 417          $where .= $wpdb->prepare(" AND post_type = %s", get_query_var('post_type'));
 418      if ( get_query_var('year') )
 419          $where .= $wpdb->prepare(" AND YEAR(post_date) = %d", get_query_var('year'));
 420      if ( get_query_var('monthnum') )
 421          $where .= $wpdb->prepare(" AND MONTH(post_date) = %d", get_query_var('monthnum'));
 422      if ( get_query_var('day') )
 423          $where .= $wpdb->prepare(" AND DAYOFMONTH(post_date) = %d", get_query_var('day'));
 424  
 425      $post_id = $wpdb->get_var("SELECT ID FROM $wpdb->posts WHERE $where AND post_status = 'publish'");
 426      if ( !$post_id )
 427          return false;
 428      return get_permalink($post_id);
 429  }
 430  
 431  add_action('template_redirect', 'redirect_canonical');
 432  
 433  ?>