trackback_cls.php

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     * 		);
     * 	echo $trackback->fetch(true, $tb_info);
     * } else {
     * 	// Something went wrong - tell my why...
     * 	echo $trackback->fetch(false, string RESPONSE);
     * }
     * ?></code>
     * 
     * @param boolean $success 
     * @param string $response 
     * @return string XML response to the caller
     */
    function fetch($success = false, $response = "")
    {
        if (!$success && empty($response)) {
            $response = "An error occured while tring to retreive trackback information...";
        } 
        // Start response to caller
        $return = '<?xml version="1.0" encoding="' . $this->encoding . '"?>' . "\n";
        $return .= "<response> \n"; 
        // Send back response...
        if ($success) {
            // Trackback retreived successfully...
            // Sending back an RSS (0.91) - trackback information from $response (array)...
            $return .= "	<error>0</error> \n";
            $return .= "	<rss version=\"0.91\"> \n";
            $return .= "	<channel> \n";
            $return .= "	  <title>" . $this->xml_safe($response['title']) . "</title> \n";
            $return .= "	  <link>" . $this->xml_safe($response['trackback']) . "</link> \n";
            $return .= "	  <description>" . $this->xml_safe($response['excerpt']) . "</description> \n";
            $return .= "	  <item> \n";
            $return .= "		<title>" . $this->xml_safe($response['title']) . "</title> \n";
            $return .= "		<link>" . $this->xml_safe($response['permalink']) . "</link> \n";
            $return .= "		<description>" . $this->xml_safe($response['excerpt']) . "</description> \n";
            $return .= "	  </item> \n";
            $return .= "	</channel> \n";
            $return .= "	</rss> \n";
        } else {
            // Something went wrong - provide reason from $response (string)...
            $return .= "	<error>1</error> \n";
            $return .= "	<message>" . $this->xml_safe($response) . "</message>\n";
        } 
        // End response to trackbacker
        $return .= "</response>";

        return $return;
    } 

    /**
     * Produces embedded RDF representing metadata about the entry,
     * allowing clients to auto-discover the TrackBack Ping URL.
     * 
     * NOTE: DATE should be string in RFC822 Format - Use RFC822_from_datetime().
     * 
     * <code><?php
     * include('trackback_cls.php');
     * $trackback = new Trackback('BLOGish', 'Ran Aroussi', 'UTF-8');
     * 
     * echo $trackback->rdf_autodiscover(string DATE, string TITLE, string EXCERPT, string PERMALINK, string TRACKBACK [, string AUTHOR]);
     * ?></code>
     * 
     * @param string $RFC822_date 
     * @param string $title 
     * @param string $excerpt 
     * @param string $permalink 
     * @param string $trackback 
     * @param string $author 
     * @return string 
     */
    function rdf_autodiscover($RFC822_date, $title, $excerpt, $permalink, $trackback, $author = "")
    {
        if (!$author) {
            $author = $this->author;
        } 

        $return = "<!-- \n";
        $return .= "<rdf:RDF xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\" \n";
        $return .= "	xmlns:dc=\"http://purl.org/dc/elements/1.1/\" \n";
        $return .= "	xmlns:trackback=\"http://madskills.com/public/xml/rss/module/trackback/\"> \n";
        $return .= "<rdf:Description \n";
        $return .= "	rdf:about=\"" . $this->xml_safe($permalink) . "\" \n";
        $return .= "	dc:identifier=\"" . $this->xml_safe($permalink) . "\" \n";
        $return .= "	trackback:ping=\"" . $this->xml_safe($trackback) . "\" \n";
        $return .= "	dc:title=\"" . $this->xml_safe($title) . "\" \n";
        $return .= "	dc:subject=\"TrackBack\" \n";
        $return .= "	dc:description=\"" . $this->xml_safe($this->cut_short($excerpt)) . "\" \n";
        $return .= "	dc:creator=\"" . $this->xml_safe($author) . "\" \n";
        $return .= "	dc:date=\"" . $RFC822_date . "\" /> \n";
        $return .= "</rdf:RDF> \n";
        $return .= "-->  \n";

        return $return;
    } 

    /**
     * Search text for links, and searches links for trackback URLs.
     * 
     * <code><?php
     * 
     * include('trackback_cls.php');
     * $trackback = new Trackback('BLOGish', 'Ran Aroussi', 'UTF-8');
     * 
     * if ($tb_array = $trackback->auto_discovery(string TEXT)) {
     * 	// Found trackbacks in TEXT. Looping...
     * 	foreach($tb_array as $tb_key => $tb_url) {
     * 	// Attempt to ping each one...
     * 		if ($trackback->ping($tb_url, string URL, [string TITLE], [string EXCERPT])) {
     * 			// Successful ping...
     * 			echo "Trackback sent to <i>$tb_url</i>...\n";
     * 		} else {
     * 			// Error pinging...
     * 			echo "Trackback to <i>$tb_url</i> failed....\n";
     * 		}
     * 	}
     * } else {
     * 	// No trackbacks in TEXT...
     * 	echo "No trackbacks were auto-discover...\n"
     * }
     * ?></code>
     * 
     * @param string $text 
     * @return array Trackback URLs.
     */
    function auto_discovery($text)
    { 
        // Get a list of UNIQUE links from text...
        // ---------------------------------------
        // RegExp to look for (0=>link, 4=>host in 'replace')
        $reg_exp = "/(http)+(s)?:(\\/\\/)((\\w|\\.)+)(\\/)?(\\S+)?/i"; 
        // Make sure each link ends with [sapce]
        $text = eregi_replace("www.", "http://www.", $text);
        $text = eregi_replace("http://http://", "http://", $text);
        $text = eregi_replace("\"", " \"", $text);
        $text = eregi_replace("'", " '", $text);
        $text = eregi_replace(">", " >", $text); 
        // Create an array with unique links
        $uri_array = array();
        if (preg_match_all($reg_exp, strip_tags($text, "<a>"), $array, PREG_PATTERN_ORDER)) {
            foreach($array[0] as $key => $link) {
                foreach((array(",", ".", ":", ";")) as $t_key => $t_value) {
                    $link = trim($link, $t_value);
                } 
                $uri_array[] = ($link);
            } 
            $uri_array = array_unique($uri_array);
        } 
        // Get the trackback URIs from those links...
        // ------------------------------------------
        // Loop through the URIs array and extract RDF segments
        $rdf_array = array(); // <- holds list of RDF segments
        foreach($uri_array as $key => $link) {
            if ($link_content = implode("", @file($link))) {
                preg_match_all('/(<rdf:RDF.*?<\/rdf:RDF>)/sm', $link_content, $link_rdf, PREG_SET_ORDER);
                for ($i = 0; $i < count($link_rdf); $i++) {
                    if (preg_match('|dc:identifier="' . preg_quote($link) . '"|ms', $link_rdf[$i][1])) {
                        $rdf_array[] = trim($link_rdf[$i][1]);
                    } 
                } 
            } 
        } 
        // Loop through the RDFs array and extract trackback URIs
        $tb_array = array(); // <- holds list of trackback URIs
        if (!empty($rdf_array)) {
            for ($i = 0; $i < count($rdf_array); $i++) {
                if (preg_match('/trackback:ping="([^"]+)"/', $rdf_array[$i], $array)) {
                    $tb_array[] = trim($array[1]);
                } 
            } 
        } 
        // Return Trackbacks
        return $tb_array;
    } 

    /**
     * Other Useful functions used in this class
     */

    /**
     * Converts MySQL datetime to a standart RFC 822 date format
     * 
     * @param string $datetime 
     * @return string RFC 822 date
     */
    function RFC822_from_datetime($datetime)
    {
        $timestamp = mktime(
            substr($datetime, 8, 2), substr($datetime, 10, 2), substr($datetime, 12, 2),
            substr($datetime, 4, 2), substr($datetime, 6, 2), substr($datetime, 0, 4)
            );
        return date("r", $timestamp);
    } 

    /**
     * Converts a string into an XML-safe string (replaces &, <, >, " and ')
     * 
     * @param string $string 
     * @return string 
     */
    function xml_safe($string)
    {
        return htmlspecialchars($string, ENT_QUOTES);
    } 

    /**
     * Cuts a string short (with "...") accroding to $max_length...
     * 
     * @param string $string 
     * @param integer $max_length 
     * @return string 
     */
    function cut_short($string, $max_length = 255)
    {
        if (strlen($string) > $max_length) {
            $string = substr($string, 0, $max_length) . '...';
        } 

        return $string;
    } 
} 

?>