TITLE="Pingback Server PHP Implementation"
--
<?php
#require('../include/db.php');

set_error_handler("rpcErrorHandler");
error_reporting(E_ERROR | E_PARSE | E_COMPILE_ERROR | E_COMPILE_WARNING | E_CORE_ERROR | E_CORE_WARNING);

function rpcErrorHandler($errorcode, $errordescription, $filename, $linenumber, $context) {
	switch ($errorcode) {
	case E_NOTICE:
	case E_WARNING:
		break;
	default:
		$body = "Error code: $errorcode\n";
		$body .= "Error description: $errordescription\n";
		$body .= "Error occured in: $filename, line $linenumber\n";
		errorlog($body);
		header('Content-type: text/xml; charset=utf-8');
		?>
		<methodResponse>
			<fault>
				<value>
					<struct>
						<member>
							<name>faultCode</name>
							<value><int>0</int></value>
						</member>
						<member>
							<name>faultString</name>
							<value>
								<string>
									Error code: <?=$errorcode?>.
									Error description: <?=$errordescription?>.
									Error occured in: <?=$filename?>, line <?=$linenumber?>.
								</string>
							</value>
						</member>
					</struct>
				</value>
			</fault>
		</methodResponse>
		<?php
		die();
	}
}

function errorlog($msg) {
	global $db;
	$query = "INSERT INTO weblog_logs (date, message) VALUES (NOW(), '".$db->escape_string($msg)."')";
	$db->query($query);
}

function pingback($method, $params, $extra) {
	global $db;
	$sourceURI = $params[0];
	$targetURI = $params[1];
	$creq = curl_init();
	curl_setopt($creq, CURLOPT_URL, $sourceURI);
	curl_setopt($creq, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($creq, CURLOPT_TIMEOUT, 15);
	if(!$data = curl_exec($creq)) {
		// This page they claim they're linking to me from, it doesn't exist!  That can't be right.
		$error = "Source URI (".$sourceURI.") does not exist (target URI was ".$targetURI.")";
		errorLog($error);
		return array('faultCode' => 0x0010, 'faultString' => $error);
	}
	if(!strstr($data, htmlspecialchars($targetURI))) {
		// Doesn't contain a valid link
		if(!strstr($data, $targetURI)) {
			// Doesn't contain an invalid link either!
			$error = "Source URI (".$sourceURI.") does not contain a link to the target URI (".$targetURI.")";
			errorLog($error);
			return array('faultCode' => 0x0011, 'faultString' => $error);
		}
	}
	if(preg_match("/<title>([^<]*)<\/title>/i", $data, $matches)) {
		$title = $matches[1];
	} else {
		$title = '';
	}
	curl_close($creq);
	#user_error("/".preg_quote(HTTPLOC, '/')."weblog\/([0-9]{4})\/([0-9]{2})\/([0-9]{2})\/([^\"]*)/"); die;
	if(!preg_match("/".preg_quote(HTTPLOC, '/')."weblog\/([0-9]{4})\/([0-9]{2})\/([0-9]{2})\/([^\"]*)/", $targetURI, $target)) {
		// The URI given was not recognised as being that of a blog post on this site.
		$error = "Specified target URI (".$targetURI.") cannot be used as a target (source URI was ".$sourceURI.")";
		errorLog($error);
		return array('faultCode' => 0x0021, 'faultString' => $error);
	}
	$query = "SELECT entryid FROM weblog_entries ";
	$query .= "WHERE YEAR(weblog_entries.date) = $target[1] ";
	$query .= "AND MONTH(weblog_entries.date) = $target[2] ";
	$query .= "AND DAYOFMONTH(weblog_entries.date) = $target[3] ";
	$query .= "AND shorttopic = '".$db->escape_string($target[4])."' ";
	$rdsBlog = $db->query($query);
	if($rdBlog = $rdsBlog->fetch_assoc()) {
		$targetid = $rdBlog['entryid'];
	} else {
		// A blog entry was specified that doesn't exist!
		$error = "Specified target URI (".$targetURI.") does not exist (source URI was ".$sourceURI.")";
		errorLog($error);
		return array('faultCode' => 0x0020, 'faultString' => $error);
	}
	$query = "SELECT COUNT(*) AS number FROM weblog_xrefs ";
	$query .= "WHERE sourceURI = '".$db->escape_string(preg_replace("/&(amp;)?/i","&amp;",$sourceURI))."' AND entryid = ".$targetid;
	$rdsPb = $db->query($query);
	$rdPb = $rdsPb->fetch_assoc();
	if($rdPb['number'] > 0) {
		// They've already pingbacked/trackbacked this post once from this source URI.  No more!!!
		$error = "The pingback from ".$sourceURI." to ".$targetURI." has already been registered";
		errorLog($error);
		return array('faultCode' => 0x0030, 'faultString' => $error);
	}
	$query = "INSERT INTO weblog_xrefs (type, date, sourceURI, entryid, title) ";
	$query .= "VALUES ('Pingback', '".gmdate('Y-m-d H:i:s')."', '".$db->escape_string(preg_replace("/&(amp;)?/i","&amp;",$sourceURI))."', ".$targetid.", ";
	$query .= "'".$db->escape_string($title)."')";
	$db->query($query);

	// Yay! We done it! We is l33t!
	$message = "Thanks! Pingback from $sourceURI to $targetURI registered";
	errorLog($message);
	return $message;
}

$server = xmlrpc_server_create();
xmlrpc_server_register_method($server, 'pingback.ping', 'pingback');

// Process request
$request = file_get_contents("php://input");
$options = array('escaping' => 'markup', 'encoding' => 'utf-8');
$response = xmlrpc_server_call_method($server, $request, null, $options);

// Output response
header('Content-type: application/xml; charset=utf-8');
echo $response;

// Clean up
xmlrpc_server_destroy($server);

exit;
?>