/system/plugins/pingback/pingback.plugin.php

<?php
/**
 * Habari Pingback plugin, enables pingback support between sites.
 * @link http://www.hixie.ch/specs/pingback/pingback The Pingback spec
 *
 * @package Habari
 */

class Pingback extends Plugin
{

	/**
	 * Register the Pingback event type with the event log
	 */
	public function action_plugin_activation( $file )
	{
		if ( realpath( $file ) == __FILE__ ) {
			EventLog::register_type( 'Pingback' );
		}
	}

	/**
	 * Unregister the Pingback event type on deactivation
	 * @todo Should we be doing this?
	 */
	public function action_plugin_deactivation( $file )
	{
		if ( realpath( $file ) == __FILE__ ) {
			EventLog::unregister_type( 'Pingback' );
		}
	}

	/**
	 * Pingback links from the post content when a post is inserted into the database.
	 * @param post The post from which to send pingbacks
	 */
	public function action_post_insert_after( $post )
	{
		// only execute if this is a published post
		if ( Post::status( 'published' ) != $post->status ) {
			return;
		}
		$this->pingback_all_links( $post->content, $post->permalink, $post );
	}

	/**
	 * Pingback mentioned links when a post is updated.
	 * @param Post $post The post is updated
	 * We invoke this function regardless of what might have been updated
	 * in the post because:
	 * 	- this will only execute if the post is published
	 *	- the pingback_all_links function keeps track of links its
	 *		already pinged, so if the content hasnt changed no
	 *		pings will be sent`
	 */
	public function action_post_update_after( $post )
	{
		// only execute if this is a published post
		if ( Post::status( 'published' ) != $post->status) {
			return;
		}
		$this->pingback_all_links( $post->content, $post->permalink, $post );
	}

	/**
	 * Add the Pingback header on single post/page requests
	 * Not to the entire site.  Clever.
	 */
	public function action_add_template_vars()
	{
		$action = Controller::get_action();
		if ( $action == 'display_post' ) {
			header( 'X-Pingback: ' . URL::get( 'xmlrpc' ) );
		}
		else {
			header( 'X-action: ' . $action );
		}
	}

	/**
	 * Receive a Pingback via XMLRPC
	 * @param array $params An array of XMLRPC parameters from the remote call
	 * @return string The success state of the pingback
	 */
	public function xmlrpc_pingback__ping( $params )
	{
		try {
			list( $source_uri, $target_uri )= $params;

			// This should really be done by an Habari core function
			$target_parse = InputFilter::parse_url( $target_uri );
			$target_stub = $target_parse['path'];
			$base_url = Site::get_path( 'base', true );

			if ( '/' != $base_url) {
				$target_stub = str_replace( $base_url, '', $target_stub );
			}

			$target_stub = trim( $target_stub, '/' );

			if ( strpos( $target_stub, '?' ) !== false ) {
				list( $target_stub, $query_string )= explode( '?', $target_stub );
			}

			// Can this be used as a target?
			$target_slug = URL::parse( $target_stub )->named_arg_values['slug'];

			if ( $target_slug === false ) {
				throw new XMLRPCException( 33 );
			}

			// Does the target exist?
			$target_post = Post::get( array( 'slug' => $target_slug ) );

			if ( $target_post === false ) {
				throw new XMLRPCException( 32 );
			}

			// Is comment allowed?
			if ( $target_post->info->comments_disabled ) {
				throw new XMLRPCException( 33 );
			}

			// Is this Pingback already registered?
			if ( Comments::get( array( 'post_id' => $target_post->id, 'url' => $source_uri, 'type' => Comment::PINGBACK ) )->count() > 0 ) {
				throw new XMLRPCException( 48 );
			}

			// Retrieve source contents
			try {
				$rr = new RemoteRequest( $source_uri );
				$rr->execute();
				if ( ! $rr->executed() ) {
					throw new XMLRPCException( 16 );
				}
				$source_contents = $rr->get_response_body();
			}
			catch ( XMLRPCException $e ) {
				// catch our special type of exception and re-throw it
				throw $e;
			}
			catch ( Exception $e ) {
				throw new XMLRPCException( -32300 );
			}

			// encoding is converted into internal encoding.
			// @todo check BOM at beginning of file before checking for a charset attribute
			$habari_encoding = MultiByte::hab_encoding();
			if ( preg_match( "/<meta[^>]+charset=([A-Za-z0-9\-\_]+)/i", $source_contents, $matches ) && strtolower( $habari_encoding ) != strtolower( $matches[1] ) ) {
				$ret = MultiByte::convert_encoding( $source_contents, $habari_encoding, $matches[1] );
				if ( $ret !== false ) {
					$source_contents = $ret;
				}
			}

			// Find the page's title
			preg_match( '/<title>(.*)<\/title>/is', $source_contents, $matches );
			$source_title = $matches[1];

			// Find the reciprocal links and their context
			preg_match( '/<body[^>]*>(.+)<\/body>/is', $source_contents, $matches );
			$source_contents_filtered = preg_replace( '/\s{2,}/is', ' ', strip_tags( $matches[1], '<a>' ) );

			if ( !preg_match( '%.{0,100}?<a[^>]*?href\\s*=\\s*("|\'|)' . $target_uri . '\\1[^>]*?'.'>(.+?)</a>.{0,100}%s', $source_contents_filtered, $source_excerpt ) ) {
				throw new XMLRPCException( 17 );
			}

			/** Sanitize Data */
			$source_excerpt = '&hellip;' . InputFilter::filter( $source_excerpt[0] ) . '&hellip;';
			$source_title = InputFilter::filter($source_title);
			$source_uri = InputFilter::filter($source_uri);

			/* Sanitize the URL */
			if (!empty($source_uri)) {
				$parsed = InputFilter::parse_url( $source_uri );
				if ( $parsed['is_relative'] ) {
					// guess if they meant to use an absolute link
					$parsed = InputFilter::parse_url( 'http://' . $source_uri );
					if ( ! $parsed['is_error'] ) {
						$source_uri = InputFilter::glue_url( $parsed );
					}
					else {
						// disallow relative URLs
						$source_uri = '';
					}
				}
				if ( $parsed['is_pseudo'] || ( $parsed['scheme'] !== 'http' && $parsed['scheme'] !== 'https' ) ) {
					// allow only http(s) URLs
					$source_uri = '';
				}
				else {
					// reconstruct the URL from the error-tolerant parsing
					// http:moeffju.net/blog/ -> http://moeffju.net/blog/
					$source_uri = InputFilter::glue_url( $parsed );
				}
			}

			// Add a new pingback comment
			$pingback = new Comment( array(
				'post_id'	=>	$target_post->id,
				'name'		=>	$source_title,
				'email'		=>	'',
				'url'		=>	$source_uri,
				'ip'		=>	sprintf( "%u", ip2long( Utils::get_ip() ) ),
				'content'	=>	$source_excerpt,
				'status'	=>	Comment::STATUS_UNAPPROVED,
				'date'		=>	HabariDateTime::date_create(),
				'type' 		=> 	Comment::PINGBACK,
				) );

			$pingback->insert();

			// Respond to the Pingback
			return 'The pingback has been registered';
		}
		catch ( XMLRPCException $e ) {
			$e->output_fault_xml();
		}
	}

	/**
	 * Send a single Pingback
	 * @param string $source_uri The URI source of the ping (here)
	 * @param string $target_uri The URI destination of the ping (there, the site linked to in the content)
	 * @param Post $post The post	object that is initiating the ping, used to track the pings that were sent
	 * @todo If receive error code of already pinged, add to the successful.
	 */
	public function send_pingback( $source_uri, $target_uri, $post = NULL )
	{
		// RemoteRequest makes it easier to retrieve the headers.
		try {
			$rr = new RemoteRequest( $target_uri );
			$rr->execute();
			if ( ! $rr->executed() ) {
				return false;
			}
		}
		catch ( Exception $e ) {
			// log the pingback error
			EventLog::log( _t( 'Unable to retrieve target, can\'t detect pingback endpoint. (Source: %1$s | Target: %2$s)', array( $source_uri, $target_uri ) ), 'err', 'Pingback' );
			return false;
		}

		$headers = $rr->get_response_headers();
		$body = $rr->get_response_body();

		// Find a Pingback endpoint.
		if ( isset( $headers['X-Pingback'] ) ) {
			$pingback_endpoint = $headers['X-Pingback'];
		}
		elseif ( preg_match( '/<link rel="pingback" href="([^"]+)" ?\/?'.'>/is', $body, $matches ) ) {
			$pingback_endpoint = $matches[1];
		}
		else {
			// No Pingback endpoint found.
			return false;
		}

		try {
			$response = XMLRPCClient::open( $pingback_endpoint )->pingback->ping( $source_uri, $target_uri );
		}
		catch ( Exception $e ) {
			EventLog::log( _t( 'Invalid Pingback endpoint - %1$s (Source: %2$s | Target: %3$s)', array( $pingback_endpoint, $source_uri, $target_uri ) ), 'err', 'Pingback' );
			return false;
		}

		if ( isset( $response->faultString ) ) {
			EventLog::log( _t( 'Pingback error: %1$s - %2$s (Source: %3$s | Target: %4$s)', array( $response->faultCode, $response->faultString, $source_uri, $target_uri ) ), 'err', 'Pingback' );
			return false;
		}
		else {
			// The pingback has been registered and is stored as a successful pingback.
			if ( is_object( $post ) ) {
				if ( isset( $post->info->pingbacks_successful ) ) {
					$pingbacks_successful = $post->info->pingbacks_successful;
					$pingbacks_successful[]= $target_uri;
					$post->info->pingbacks_successful = $pingbacks_successful;
				}
				else {
					$post->info->pingbacks_successful = array( $target_uri );
				}
				$post->info->commit();
			}
			return true;
		}
	}

	/**
	 * Scan all links in the content and send them a Pingback.
	 * @param string $content The post content to search
	 * @param string $source_uri The source of the content
	 * @param Post $post The post object of the source of the ping
	 * @param boolean $force If true, force the system to ping all links even if that had been pinged before
	 */
	public function pingback_all_links( $content, $source_uri, $post = NULL, $force = false )
	{
		
		$tokenizer = new HTMLTokenizer( $content, false );
		$tokens = $tokenizer->parse();

		// slice out only A tags
		$slices = $tokens->slice( array( 'a' ), array( ) );

		$urls = array();
		foreach ( $slices as $slice ) {

			// if there is no href attribute, just skip it, though there is something wrong
			if ( !isset( $slice[0]['attrs']['href'] ) ) {
				continue;
			}
			else {
				$url = $slice[0]['attrs']['href'];
			}

			// make sure it's a valid URL before we waste our time
			$parsed = InputFilter::parse_url( $url );
			
			if ( $parsed['is_error'] || $parsed['is_pseudo'] || $parsed['is_relative'] ) {
				continue;
			}
			else {
				$urls[] = $url;
			}

		}
		
		if ( is_object( $post ) && isset( $post->info->pingbacks_successful ) ) {
			$fn = ( $force === true ) ? 'array_merge' : 'array_diff';
			$links = $fn( $urls, $post->info->pingbacks_successful );
		}
		else {
			$links = $urls;
		}

		$links = array_unique( $links );

		foreach ( $links as $target_uri ) {
			if ( $this->send_pingback( $source_uri, $target_uri, $post ) ) {
				EventLog::log( _t( 'Sent pingbacks for "%1$s", target: %2$s', array( $post->title, $target_uri ) ), 'info', 'Pingback' );
			}
		}
	}

	/**
	 * Add the pingback options to the options page
	 * @param array $items The array of option on the options page
	 * @return array The array of options including new options for pingback
	 */
	public function filter_admin_option_items($items) 
	{
		$items[_t('Publishing')]['pingback_send'] = array(
			'label' => _t('Send Pingbacks to Links'),
			'type' => 'checkbox',
			'helptext' => '',
		);

		return $items;
	}
	
	/**
	 * Returns a full qualified URL of the specified post based on the comments count.
 	 *
	 * Passed strings are localized prior to parsing therefore to localize "%d Comments" in french, it would be "%d Commentaires".
	 *
	 * Since we use sprintf() in the final concatenation, you must format passed strings accordingly.
	 *
	 * @param Theme $theme The current theme object
	 * @param Post $post Post object used to build the pingback link
	 * @param string $zero String to return when there are no pingbacks
	 * @param string $one String to return when there is one pingback
	 * @param string $many String to return when there are more than one pingback
	 * @return string String to display for pingback count
	 */
	public function theme_pingback_count( $theme, $post, $zero = '', $one = '', $many = '' )
	{
		$count = $post->comments->pingbacks->approved->count;
		if ( empty( $zero ) ) {
			$zero = _t( '%d Pingbacks' );
		}
		if ( empty( $one ) ) {
			$one = _t( '%d Pingback' );
		}
		if ( empty( $many ) ) {
			$many = _t( '%d Pingbacks' );
		}

		if ($count >= 1) {
			$text = _n( $one, $many, $count );
		}
		else {
			$text = $zero;
		}
		return sprintf( $text, $count );
	}
	
}
?>