TrackBack.php

<?php
//
// Copyright (c) 2004 KOYAMA, Tetsuji All Right Reserved.
// $Id: TrackBack.php,v 1.2 2008/06/27 01:34:45 S.Li Exp $
//
// Net_TrackBack Class
//
// Simple example:
//
// $tb = new Net_trackBack;
// $id = $tb->getId();
// // you must validate TrackBack ID
//
// if ($tb->isPing()) {
//     $data = $tb->analyzePing($_POST);
//     // store data in your storage
//     $tb->displayResult($tb->getPingXML(true));
// } else {
//     // listup
//     // load TrackBack data from your storage
//     $items = array();
//     $tb->displayResult($tb->toRSSXML($items));
// }
//

require_once 'PEAR.php';
require_once 'HTTP/Request.php';

/**
* User-Agent name when pinging TrackBack
*/
define('NET_TRACKBACK_DEFAULT_USER_AGENT', 'Net_TrackBack');
/**
* Error code
*/
define('NET_TRACKBACK_ERROR_INVALID_PATHINFO',  -1);
define('NET_TRACKBACK_ERROR_INVALID_PARAM',     -2);
define('NET_TRACKBACK_ERROR_BAD_RESPONSE',      -3);
define('NET_TRACKBACK_ERROR_REMOTE_ERROR',      -4);
class Net_TrackBack{
    /**
     * key names of TrackBack
     * @var array
     */
    var $ping_keys = array('title', 'url', 'excerpt', 'blog_name');
    /**
     * Send a TrackBack ping.
     * (used by TrackBack client.)
     *
     * @param  string $url        TrackBack URL
     * @param  array  $data       data of TrackBack
     * @param  string $user_agent User-Agent (Optional)
     * @param  string $charset    Character set of data (Optional)
     *
     * @return mixed  true on success. PEAR_Error on failure.
     *
     * @access public
     */
    function sendPing($url, $data,
                      $user_agent = NET_TRACKBACK_DEFAULT_USER_AGENT,
                      $charset = null) {
        if (!is_array($data)) {
            return PEAR::raiseError('Invalid Ping Data',
                                    NET_TRACKBACK_ERROR_INVALID_PARAM);
        }
        $params = array('method' => HTTP_REQUEST_METHOD_POST);
        $req =& new HTTP_Request($url, $params);
        foreach ($data as $key => $val) {
            $req->addPostData($key, $val);
        }
        $req->addHeader('User-Agent', $user_agent);
        if (!empty($charset)) {
            $req->addHeader('Content-Type',
                            'application/x-www-form-urlencoded; charset='.
                            $charset);
        }
        $result = $req->sendRequest();
        if (PEAR::isError($result)) {
            return $result;
        }
        $response = $req->getResponseBody();
        $result = preg_match('!<error>(\d+)</error>!', $response, $matches);
        if ($result == 0) {
            return PEAR::raiseError("Bad Response format from $url",
                                    NET_TRACKBACK_ERROR_BAD_RESPONSE);
        }
        $errnum = $matches[1];
        if ($errnum != 0) {
            $result = preg_match('!<message>(.+?)</message>!ms',
                                 $response, $matches);
            if ($result == 1) {
                $message = $matches[1];
            } else {
                $message = '(unrecognized message)';
            }
            return PEAR::raiseError('Server returns error: ' . $message,
                                    NET_TRACKBACK_ERROR_REMOTE_ERROR);
        }
        return true;
    }
    /**
     * Discover TrackBack URL from given URL
     * (used by TrackBack client.)
     *
     * @param  string $url The URL to discover
     *
     * @return mixed TrackBack URL on success.
     *               false on no TrackBack URL.
     *               PEAR_Error on failure.
     *
     * @access public
     */
    function discover($url) {
        if (empty($url)) {
            return PEAR::raiseError('URL is empty');
        }
        $params = array('method' => HTTP_REQUEST_METHOD_GET,
                        'timeout' => 15);
        $req =& new HTTP_Request($url, $params);
        $result = $req->sendRequest();
        if (PEAR::isError($result)) {
            return $result;
        }
        $body = $req->getResponseBody();
        $nmatch = preg_match('!(<rdf:RDF.*?</rdf:RDF>)!ms', $body, $matches);
        if ($nmatch == 0) {
            return false;
        }
        $result = array();
        for ($i = 0; $i < $nmatch; ++$i) {
            $url_no_anchor = $url;
            $pos = strrpos($url, '#');
            if ($pos) {
                $url_no_anchor = substr($url, 0, $pos);
            }
            $rdf =& $matches[$i + 1];
            if (preg_match('!dc:identifier="([^"]+)"!m', $rdf, $perm_urls) == 0) {
                continue;
            }
            if ($perm_urls[1] != $url && $perm_urls[1] != $url_no_anchor) {
                continue;
            }
            if (preg_match('!trackback:ping="([^"]+)"!m', $rdf, $pings)) {
                $result[] = $pings[1];
            } else if (preg_match('!about="([^"]+)"!m', $rdf, $abouts)) {
                $result[] = $abouts[1];
            }
        }
        return $result;
    }
    /**
     * Return ping received or not
     * (used by TrackBack server.)
     *
     * @return bool   true when ping requested
     *
     * @access public
     * @see Net_TrackBack::isListup()
     */
    function isPing() {
        return ($_SERVER['REQUEST_METHOD'] == 'POST');
    }
    /**
     * Return listup requested or not
     * (used by TrackBack server.)
     *
     * @return bool   true when listup requested
     *
     * @access public
     * @see Net_TrackBack::isPing()
     */
    function isListup() {
        return ($_SERVER['REQUEST_METHOD'] == 'GET');
    }
    /**
     * Pick up TrackBack related valiable from original data
     * (used by TrackBack server.)
     *
     * @param  array $data   Received ping data (may be $_POST)
     *
     * @return array  the data of TrackBack ping
     *
     * @access public
     */
    function analyzePing($data) {
        $result = array();
        foreach ($this->ping_keys as $key) {
            if (array_key_exists($key, $data)) {
                $result[$key] = $data[$key];
            }
        }
        return $result;
    }
    /**
     * Get TrackBack ID from PATH_INFO
     * (used by TrackBack server.)
     *
     * @return mixed TrackBack ID or PEAR_Error on failure
     * @access public
     */
    function getId() {

        if (array_key_exists('PATH_INFO', $_SERVER)) {
            $pathinfo = $_SERVER['PATH_INFO'];
        } else {
            $pathinfo = '';
        }
        if (substr($pathinfo, 0, 1) == '/') {
            $id = substr($pathinfo, 1);
        } else {
            return PEAR::raiseError('Invalid PATH_INFO',
                                    NET_TRACKBACK_ERROR_INVALID_PATHINFO);
        }
        $pos = strpos($id, '/');
        if ($pos != false) {
            $id = substr($id, 0, $pos);
        }
        return $id;
    }
    /**
     * Display result of TrackBack ping/listup
     * (used by TrackBack server.)
     *
     * @param  string $message output message
     *
     * @return bool   true only
     *
     * @access public
     */
    function displayResult($message) {
        header('Content-Type: text/xml');
        echo $message;
        return true;
    }
    /**
     * Format result for TrackBack ping
     * (used by TrackBack server.)
     *
     * @param  bool   $success Result of ping
     * @param  string $message Message when error occured
     *
     * @return string generated XML to reply
     *
     * @access public
     */
    function getPingXML($success, $message = null) {
        $head = '<?xml version="1.0" encoding="iso-8859-1" ?>' . "\n" .
            '<response>' . "\n";
        $foot = '</response>';
        if ($success) {
            $result = $head . '<error>0</error>' . "\n" . $foot;
        } else {
            if (empty($message)) {
                $message = 'Unknown Error';
            }
            $result = $head . '<error>1</error>' . "\n" .
                "<message>$message</message>\n" . $foot;
        }
        return $result;
    }
    /**
     * Generates RSS to listup TrackBack datas
     * (used by TrackBack server.)
     *
     * @param  array  $items
     * @param  string $title
     * @param  string $link
     * @param  string $description
     * @param  string $lang
     *
     * @return string generated XML to reply
     *
     * @access public
     */
    function toRSSXML($items,
                      $title = 'TrackBacks list',
                      $link = null,
                      $description = 'TrackBack items',
                      $lang = 'en-us') {
        $header =
            '<?xml version="1.0" encoding="utf-8" ?>'."\n".
            "<response>\n".
            "<error>0</error>\n".
            '<rss version="0.91"><channel>'."\n".
            "<title>%s</title>\n".
            "<link>%s</link>\n".
            "<description>%s</description>\n".
            "<language>%s</language>\n";
        $footer = "</channel>\n</rss></response>\n";
        if (empty($link)) {
            $link = 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'];
        }
        $rss = sprintf($header, $title, $link, $description, $lang);
        foreach ($items as $item) {
            $keys = array('title' => 'title',
                          'url' => 'link',
                          'excerpt' => 'description');
            $part = '';
            foreach ($keys as $key => $itemname) {
                if (isset($item[$key])) {
                    $part .= sprintf("<%s>%s</%s>\n",
                                     $itemname,
                                     htmlspecialchars($item[$key]),
                                     $itemname);
                }
            }
            if (!empty($part)) {
                $rss .= "<item>\n" . $part . "</item>\n";
            }
        }
        return $rss . $footer;
    }
    /**
     * Generate RDF to embed HTML content.
     * (used by TrackBack server.)
     *
     * @param  array $data
     * @return mixed generated RDF to embeded on success,
     *               or PEAR_Error object on failure
     * @access public
     */
    function toEmbededRDF($data) {
        $rdfspec = 
            '<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"'.
            "\n\t". 'xmlns:trackback="http://madskills.com/public/xml/rss/module/trackback/"'.
            "\n\t". 'xmlns:dc="http://purl.org/dc/elements/1.1/">'."\n";
        $rdffmt = 
            '<rdf:Description' ."\n".
            '    rdf:about="%s"' ."\n".
            '    trackback:ping="%s"' ."\n".
            '    dc:title="%s"' ."\n".
            '    dc:identifier="%s"' ."\n".
            '    dc:description="%s"' ."\n".
            '    dc:creator="%s"' ."\n".
            '    dc:date="%s" />' ."\n".
            '</rdf:RDF>' ."\n";
        $keys = array('about', 'ping', 'title', 'identifier',
                      'description', 'creator', 'date');
        foreach ($keys as $key) {
            if (!array_key_exists($key, $data)) {
                PEAR::raiseError("$key is required key in data",
                                 NET_TRACKBACK_ERROR_INVALID_PARAM);
            }
        }
        return $rdfspec .
            sprintf($rdffmt,
                    $data['about'],
                    $data['ping'],
                    $data['title'],
                    $data['identifier'],
                    $data['description'],
                    $data['creator'],
                    $data['date']);
    }
}
?>