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   1  <?php
   2  /**
   3   * Handle Trackbacks and Pingbacks Sent to WordPress
   4   *
   5   * @since 0.71
   6   *
   7   * @package WordPress
   8   * @subpackage Trackbacks
   9   */
  10  
  11  if ( empty( $wp ) ) {
  12      require_once  __DIR__ . '/wp-load.php';
  13      wp( array( 'tb' => '1' ) );
  14  }
  15  
  16  // Always run as an unauthenticated user.
  17  wp_set_current_user( 0 );
  18  
  19  /**
  20   * Response to a trackback.
  21   *
  22   * Responds with an error or success XML message.
  23   *
  24   * @since 0.71
  25   *
  26   * @param int|bool $error         Whether there was an error.
  27   *                                Default '0'. Accepts '0' or '1', true or false.
  28   * @param string   $error_message Error message if an error occurred. Default empty string.
  29   */
  30  function trackback_response( $error = 0, $error_message = '' ) {
  31      header( 'Content-Type: text/xml; charset=' . get_option( 'blog_charset' ) );
  32  
  33      if ( $error ) {
  34          echo '<?xml version="1.0" encoding="utf-8"?' . ">\n";
  35          echo "<response>\n";
  36          echo "<error>1</error>\n";
  37          echo "<message>$error_message</message>\n";
  38          echo '</response>';
  39          die();
  40      } else {
  41          echo '<?xml version="1.0" encoding="utf-8"?' . ">\n";
  42          echo "<response>\n";
  43          echo "<error>0</error>\n";
  44          echo '</response>';
  45      }
  46  }
  47  
  48  if ( ! isset( $_GET['tb_id'] ) || ! $_GET['tb_id'] ) {
  49      $post_id = explode( '/', $_SERVER['REQUEST_URI'] );
  50      $post_id = (int) $post_id[ count( $post_id ) - 1 ];
  51  }
  52  
  53  $trackback_url = isset( $_POST['url'] ) ? $_POST['url'] : '';
  54  $charset       = isset( $_POST['charset'] ) ? $_POST['charset'] : '';
  55  
  56  // These three are stripslashed here so they can be properly escaped after mb_convert_encoding().
  57  $title     = isset( $_POST['title'] ) ? wp_unslash( $_POST['title'] ) : '';
  58  $excerpt   = isset( $_POST['excerpt'] ) ? wp_unslash( $_POST['excerpt'] ) : '';
  59  $blog_name = isset( $_POST['blog_name'] ) ? wp_unslash( $_POST['blog_name'] ) : '';
  60  
  61  if ( $charset ) {
  62      $charset = str_replace( array( ',', ' ' ), '', strtoupper( trim( $charset ) ) );
  63  
  64      // Validate the specified "sender" charset is available on the receiving site.
  65      if ( function_exists( 'mb_list_encodings' ) && ! in_array( $charset, mb_list_encodings(), true ) ) {
  66          $charset = '';
  67      }
  68  }
  69  
  70  if ( ! $charset ) {
  71      $charset = 'ASCII, UTF-8, ISO-8859-1, JIS, EUC-JP, SJIS';
  72  }
  73  
  74  // No valid uses for UTF-7.
  75  if ( str_contains( $charset, 'UTF-7' ) ) {
  76      die;
  77  }
  78  
  79  // For international trackbacks.
  80  if ( function_exists( 'mb_convert_encoding' ) ) {
  81      $title     = mb_convert_encoding( $title, get_option( 'blog_charset' ), $charset );
  82      $excerpt   = mb_convert_encoding( $excerpt, get_option( 'blog_charset' ), $charset );
  83      $blog_name = mb_convert_encoding( $blog_name, get_option( 'blog_charset' ), $charset );
  84  }
  85  
  86  // Escape values to use in the trackback.
  87  $title     = wp_slash( $title );
  88  $excerpt   = wp_slash( $excerpt );
  89  $blog_name = wp_slash( $blog_name );
  90  
  91  if ( is_single() || is_page() ) {
  92      $post_id = $posts[0]->ID;
  93  }
  94  
  95  if ( ! isset( $post_id ) || ! (int) $post_id ) {
  96      trackback_response( 1, __( 'I really need an ID for this to work.' ) );
  97  }
  98  
  99  if ( empty( $title ) && empty( $trackback_url ) && empty( $blog_name ) ) {
 100      // If it doesn't look like a trackback at all.
 101      wp_redirect( get_permalink( $post_id ) );
 102      exit;
 103  }
 104  
 105  if ( ! empty( $trackback_url ) && ! empty( $title ) ) {
 106      /**
 107       * Fires before the trackback is added to a post.
 108       *
 109       * @since 4.7.0
 110       *
 111       * @param int    $post_id       Post ID related to the trackback.
 112       * @param string $trackback_url Trackback URL.
 113       * @param string $charset       Character set.
 114       * @param string $title         Trackback title.
 115       * @param string $excerpt       Trackback excerpt.
 116       * @param string $blog_name     Site name.
 117       */
 118      do_action( 'pre_trackback_post', $post_id, $trackback_url, $charset, $title, $excerpt, $blog_name );
 119  
 120      header( 'Content-Type: text/xml; charset=' . get_option( 'blog_charset' ) );
 121  
 122      if ( ! pings_open( $post_id ) ) {
 123          trackback_response( 1, __( 'Sorry, trackbacks are closed for this item.' ) );
 124      }
 125  
 126      $title   = wp_html_excerpt( $title, 250, '&#8230;' );
 127      $excerpt = wp_html_excerpt( $excerpt, 252, '&#8230;' );
 128  
 129      $comment_post_id      = (int) $post_id;
 130      $comment_author       = $blog_name;
 131      $comment_author_email = '';
 132      $comment_author_url   = $trackback_url;
 133      $comment_content      = "<strong>$title</strong>\n\n$excerpt";
 134      $comment_type         = 'trackback';
 135  
 136      $dupe = $wpdb->get_results(
 137          $wpdb->prepare(
 138              "SELECT * FROM $wpdb->comments WHERE comment_post_ID = %d AND comment_author_url = %s",
 139              $comment_post_id,
 140              $comment_author_url
 141          )
 142      );
 143  
 144      if ( $dupe ) {
 145          trackback_response( 1, __( 'There is already a ping from that URL for this post.' ) );
 146      }
 147  
 148      $commentdata = array(
 149          'comment_post_ID' => $comment_post_id,
 150      );
 151  
 152      $commentdata += compact(
 153          'comment_author',
 154          'comment_author_email',
 155          'comment_author_url',
 156          'comment_content',
 157          'comment_type'
 158      );
 159  
 160      $result = wp_new_comment( $commentdata );
 161  
 162      if ( is_wp_error( $result ) ) {
 163          trackback_response( 1, $result->get_error_message() );
 164      }
 165  
 166      $trackback_id = $wpdb->insert_id;
 167  
 168      /**
 169       * Fires after a trackback is added to a post.
 170       *
 171       * @since 1.2.0
 172       *
 173       * @param int $trackback_id Trackback ID.
 174       */
 175      do_action( 'trackback_post', $trackback_id );
 176  
 177      trackback_response( 0 );
 178  }