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   1  <?php
   2  // Based on "Permalink Redirect" from Scott Yang and "Enforce www. Preference" by Mark Jaquith
   3  
   4  function redirect_canonical($requested_url=NULL, $do_redirect=true) {
   5      global $wp_rewrite, $posts, $is_IIS;
   6  
   7      if ( is_feed() || is_trackback() || is_search() || is_comments_popup() || is_admin() || $is_IIS || ( isset($_POST) && count($_POST) ) || is_preview() )
   8          return;
   9  
  10      if ( !$requested_url ) {
  11          // build the URL in the address bar
  12          $requested_url  = ( isset($_SERVER['HTTPS'] ) && strtolower($_SERVER['HTTPS']) == 'on' ) ? 'https://' : 'http://';
  13          $requested_url .= $_SERVER['HTTP_HOST'];
  14          $requested_url .= $_SERVER['REQUEST_URI'];
  15      }
  16  
  17      $original = @parse_url($requested_url);
  18      if ( false === $original )
  19          return;
  20  
  21      // Some PHP setups turn requests for / into /index.php in REQUEST_URI
  22      $original['path'] = preg_replace('|/index\.php$|', '/', $original['path']);
  23  
  24      $redirect = $original;
  25      $redirect_url = false;
  26  
  27      // These tests give us a WP-generated permalink
  28      if ( is_404() ) {
  29          $redirect_url = redirect_guess_404_permalink();
  30      } elseif ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() ) {
  31          // rewriting of old ?p=X, ?m=2004, ?m=200401, ?m=20040101
  32          if ( is_single() && isset($_GET['p']) ) {
  33              if ( $redirect_url = get_permalink(get_query_var('p')) )
  34                  $redirect['query'] = remove_query_arg('p', $redirect['query']);
  35          } elseif ( is_page() && isset($_GET['page_id']) ) {
  36              if ( $redirect_url = get_permalink(get_query_var('page_id')) )
  37                  $redirect['query'] = remove_query_arg('page_id', $redirect['query']);
  38          } elseif ( isset($_GET['m']) && ( is_year() || is_month() || is_day() ) ) {
  39              $m = get_query_var('m');
  40              switch ( strlen($m) ) {
  41                  case 4: // Yearly
  42                      $redirect_url = get_year_link($m);
  43                      break;
  44                  case 6: // Monthly
  45                      $redirect_url = get_month_link( substr($m, 0, 4), substr($m, 4, 2) );
  46                      break;
  47                  case 8: // Daily
  48                      $redirect_url = get_day_link(substr($m, 0, 4), substr($m, 4, 2), substr($m, 6, 2));
  49                      break;
  50              }
  51              if ( $redirect_url )
  52                  $redirect['query'] = remove_query_arg('m', $redirect['query']);
  53          // now moving on to non ?m=X year/month/day links
  54          } elseif ( is_day() && get_query_var('year') && get_query_var('monthnum') && isset($_GET['day']) ) {
  55              if ( $redirect_url = get_day_link(get_query_var('year'), get_query_var('monthnum'), get_query_var('day')) )
  56                  $redirect['query'] = remove_query_arg(array('year', 'monthnum', 'day'), $redirect['query']);
  57          } elseif ( is_month() && get_query_var('year') && isset($_GET['monthnum']) ) {
  58              if ( $redirect_url = get_month_link(get_query_var('year'), get_query_var('monthnum')) )
  59                  $redirect['query'] = remove_query_arg(array('year', 'monthnum'), $redirect['query']);
  60          } elseif ( is_year() && isset($_GET['year']) ) {
  61              if ( $redirect_url = get_year_link(get_query_var('year')) )
  62                  $redirect['query'] = remove_query_arg('year', $redirect['query']);
  63          } elseif ( is_category() && isset($_GET['cat']) ) {
  64              if ( $redirect_url = get_category_link(get_query_var('cat')) )
  65                  $redirect['query'] = remove_query_arg('cat', $redirect['query']);
  66          } elseif ( is_author() && isset($_GET['author']) ) {
  67              $author = get_userdata(get_query_var('author'));
  68              if ( false !== $author && $redirect_url = get_author_link(false, $author->ID, $author->user_nicename) )
  69                  $redirect['query'] = remove_query_arg('author', $redirect['author']);
  70          }
  71  
  72      // paging
  73          if ( $paged = get_query_var('paged') ) {
  74              if ( $paged > 0 ) {
  75                  if ( !$redirect_url )
  76                      $redirect_url = $requested_url;
  77                  $paged_redirect = @parse_url($redirect_url);
  78                  $paged_redirect['path'] = preg_replace('|/page/[0-9]+?(/+)?$|', '/', $paged_redirect['path']); // strip off any existing paging
  79                  $paged_redirect['path'] = preg_replace('|/index.php/?$|', '/', $paged_redirect['path']); // strip off trailing /index.php/
  80                  if ( $paged > 1 && !is_single() ) {
  81                      $paged_redirect['path'] = trailingslashit($paged_redirect['path']);
  82                      if ( $wp_rewrite->using_index_permalinks() && strpos($paged_redirect['path'], '/index.php/') === false )
  83                          $paged_redirect['path'] .= 'index.php/';
  84                      $paged_redirect['path'] .= user_trailingslashit("page/$paged", 'paged');
  85                  } elseif ( !is_home() && !is_single() ){
  86                      $paged_redirect['path'] = user_trailingslashit($paged_redirect['path'], 'paged');
  87                  }
  88                  $redirect_url = $paged_redirect['scheme'] . '://' . $paged_redirect['host'] . $paged_redirect['path'];
  89                  $redirect['path'] = $paged_redirect['path'];
  90              }
  91              $redirect['query'] = remove_query_arg('paged', $redirect['query']);
  92          }
  93      }
  94  
  95      // tack on any additional query vars
  96      if ( $redirect_url && $redirect['query'] ) {
  97          if ( strpos($redirect_url, '?') !== false )
  98              $redirect_url .= '&';
  99          else
 100              $redirect_url .= '?';
 101          $redirect_url .= $redirect['query'];
 102      }
 103  
 104      if ( $redirect_url )
 105          $redirect = @parse_url($redirect_url);
 106  
 107      // www.example.com vs example.com
 108      $user_home = @parse_url(get_option('home'));
 109      $redirect['host'] = $user_home['host'];
 110  
 111      // Handle ports
 112      if ( isset($user_home['port']) )
 113          $redirect['port'] = $user_home['port'];
 114      else
 115          unset($redirect['port']);
 116  
 117      // trailing /index.php/
 118      $redirect['path'] = preg_replace('|/index.php/$|', '/', $redirect['path']);
 119  
 120      // strip /index.php/ when we're not using PATHINFO permalinks
 121      if ( !$wp_rewrite->using_index_permalinks() )
 122          $redirect['path'] = str_replace('/index.php/', '/', $redirect['path']);
 123  
 124      // trailing slashes
 125      if ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() && !is_404() && (!is_home() || ( is_home() && (get_query_var('paged') > 1) ) ) ) {
 126          $user_ts_type = '';
 127          if ( get_query_var('paged') > 0 ) {
 128              $user_ts_type = 'paged';
 129          } else {
 130              foreach ( array('single', 'category', 'page', 'day', 'month', 'year') as $type ) {
 131                  $func = 'is_' . $type;
 132                  if ( call_user_func($func) )
 133                      $user_ts_type = $type;
 134                      break;
 135                  }
 136              }
 137          $redirect['path'] = user_trailingslashit($redirect['path'], $user_ts_type);
 138      } elseif ( is_home() ) {
 139          $redirect['path'] = trailingslashit($redirect['path']);
 140      }
 141  
 142      // Always trailing slash the 'home' URL
 143      if ( $redirect['path'] == $user_home['path'] )
 144          $redirect['path'] = trailingslashit($redirect['path']);
 145  
 146      // Ignore differences in host capitalization, as this can lead to infinite redirects
 147      if ( strtolower($original['host']) == strtolower($redirect['host']) )
 148          $redirect['host'] = $original['host'];
 149  
 150      if ( array($original['host'], $original['port'], $original['path'], $original['query']) !== array($redirect['host'], $redirect['port'], $redirect['path'], $redirect['query']) ) {
 151          $redirect_url = $redirect['scheme'] . '://' . $redirect['host'];
 152          if ( isset($redirect['port']) )
 153               $redirect_url .= ':' . $redirect['port'];
 154          $redirect_url .= $redirect['path'];
 155          if ( $redirect['query'] )
 156              $redirect_url .= '?' . $redirect['query'];
 157      }
 158  
 159      if ( $redirect_url && $redirect_url != $requested_url ) {
 160          // var_dump($redirect_url); die();
 161          $redirect_url = apply_filters('redirect_canonical', $redirect_url, $requested_url);
 162          if ( $do_redirect) {
 163              // protect against chained redirects
 164              if ( !redirect_canonical($redirect_url, false) ) {
 165                  wp_redirect($redirect_url, 301);
 166                  exit();
 167              } else {
 168                  return false;
 169              }
 170          } else {
 171              return $redirect_url;
 172          }
 173      } else {
 174          return false;
 175      }
 176  }
 177  
 178  function redirect_guess_404_permalink() {
 179      global $wp_query, $wpdb;
 180      if ( !get_query_var('name') )
 181          return false;
 182  
 183      $where = $wpdb->prepare("post_name LIKE %s", get_query_var('name') . '%');
 184  
 185      // if any of year, monthnum, or day are set, use them to refine the query
 186      if ( get_query_var('year') )
 187          $where .= $wpdb->prepare(" AND YEAR(post_date) = %d", get_query_var('year'));
 188      if ( get_query_var('monthnum') )
 189          $where .= $wpdb->prepare(" AND MONTH(post_date) = %d", get_query_var('monthnum'));
 190      if ( get_query_var('day') )
 191          $where .= $wpdb->prepare(" AND DAYOFMONTH(post_date) = %d", get_query_var('day'));
 192  
 193      $post_id = $wpdb->get_var("SELECT ID FROM $wpdb->posts WHERE $where AND post_status = 'publish'");
 194      if ( !$post_id )
 195          return false;
 196      return get_permalink($post_id);
 197  }
 198  
 199  add_action('template_redirect', 'redirect_canonical');
 200  
 201  ?>