<?php
/**
* Handle Trackbacks and Pingbacks Sent to WordPress
*
* @since 0.71
*
* @package WordPress
* @subpackage Trackbacks
*/

if (empty($wp)) {
require_once( dirname( __FILE__ ) . '/wp-load.php' );
wp( array( 'tb' => '1' ) );
}

/**
* Response to a trackback.
*
* Responds with an error or success XML message.
*
* @since 0.71
*
* @param mixed $error Whether there was an error.
* Default '0'. Accepts '0' or '1', true or false.
* @param string $error_message Error message if an error occurred.
*/
function trackback_response($error = 0, $error_message = '') {
header('Content-Type: text/xml; charset=' . get_option('blog_charset') );
if ($error) {
echo '<?xml version="1.0" encoding="utf-8"?'.">\n";
echo "<response>\n";
echo "<error>1</error>\n";
echo "<message>$error_message</message>\n";
echo "</response>";
die();
} else {
echo '<?xml version="1.0" encoding="utf-8"?'.">\n";
echo "<response>\n";
echo "<error>0</error>\n";
echo "</response>";
}
}

// Trackback is done by a POST.
$request_array = 'HTTP_POST_VARS';

if ( !isset($_GET['tb_id']) || !$_GET['tb_id'] ) {
$tb_id = explode('/', $_SERVER['REQUEST_URI']);
$tb_id = intval( $tb_id[ count($tb_id) - 1 ] );
}

$tb_url = isset($_POST['url']) ? $_POST['url'] : '';
$charset = isset($_POST['charset']) ? $_POST['charset'] : '';

// These three are stripslashed here so they can be properly escaped after mb_convert_encoding().
$title = isset($_POST['title']) ? wp_unslash($_POST['title']) : '';
$excerpt = isset($_POST['excerpt']) ? wp_unslash($_POST['excerpt']) : '';
$blog_name = isset($_POST['blog_name']) ? wp_unslash($_POST['blog_name']) : '';

if ($charset)
$charset = str_replace( array(',', ' '), '', strtoupper( trim($charset) ) );
else
$charset = 'ASCII, UTF-8, ISO-8859-1, JIS, EUC-JP, SJIS';

// No valid uses for UTF-7.
if ( false !== strpos($charset, 'UTF-7') )
die;

// For international trackbacks.
if ( function_exists('mb_convert_encoding') ) {
$title = mb_convert_encoding($title, get_option('blog_charset'), $charset);
$excerpt = mb_convert_encoding($excerpt, get_option('blog_charset'), $charset);
$blog_name = mb_convert_encoding($blog_name, get_option('blog_charset'), $charset);
}

// Now that mb_convert_encoding() has been given a swing, we need to escape these three.
$title = wp_slash($title);
$excerpt = wp_slash($excerpt);
$blog_name = wp_slash($blog_name);

if ( is_single() || is_page() )
$tb_id = $posts[0]->ID;

if ( !isset($tb_id) || !intval( $tb_id ) )
trackback_response( 1, __( 'I really need an ID for this to work.' ) );

if (empty($title) && empty($tb_url) && empty($blog_name)) {
// If it doesn't look like a trackback at all.
wp_redirect(get_permalink($tb_id));
exit;
}

if ( !empty($tb_url) && !empty($title) ) {
/**
* Fires before the trackback is added to a post.
*
* @since 4.7.0
*
* @param int $tb_id Post ID related to the trackback.
* @param string $tb_url Trackback URL.
* @param string $charset Character Set.
* @param string $title Trackback Title.
* @param string $excerpt Trackback Excerpt.
* @param string $blog_name Blog Name.
*/
do_action( 'pre_trackback_post', $tb_id, $tb_url, $charset, $title, $excerpt, $blog_name );

header('Content-Type: text/xml; charset=' . get_option('blog_charset') );

if ( !pings_open($tb_id) )
trackback_response( 1, __( 'Sorry, trackbacks are closed for this item.' ) );

$title = wp_html_excerpt( $title, 250, '&#8230;' );
$excerpt = wp_html_excerpt( $excerpt, 252, '&#8230;' );

$comment_post_ID = (int) $tb_id;
$comment_author = $blog_name;
$comment_author_email = '';
$comment_author_url = $tb_url;
$comment_content = "<strong>$title</strong>\n\n$excerpt";
$comment_type = 'trackback';

$dupe = $wpdb->get_results( $wpdb->prepare("SELECT * FROM $wpdb->comments WHERE comment_post_ID = %d AND comment_author_url = %s", $comment_post_ID, $comment_author_url) );
if ( $dupe )
trackback_response( 1, __( 'We already have a ping from that URL for this post.' ) );

$commentdata = compact('comment_post_ID', 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_content', 'comment_type');

wp_new_comment($commentdata);
$trackback_id = $wpdb->insert_id;

/**
* Fires after a trackback is added to a post.
*
* @since 1.2.0
*
* @param int $trackback_id Trackback ID.
*/
do_action( 'trackback_post', $trackback_id );
trackback_response( 0 );
}