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+<?php
+/**
+ * Laconica, the distributed open-source microblogging tool
+ *
+ * Plugin to do linkbacks for notices containing links
+ *
+ * PHP version 5
+ *
+ * LICENCE: This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category Plugin
+ * @package Laconica
+ * @author Evan Prodromou <evan@controlyourself.ca>
+ * @copyright 2009 Control Yourself, Inc.
+ * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link http://laconi.ca/
+ */
+
+if (!defined('LACONICA')) {
+ exit(1);
+}
+
+require_once('Auth/Yadis/Yadis.php');
+
+define('LINKBACKPLUGIN_VERSION', '0.1');
+
+/**
+ * Plugin to do linkbacks for notices containing URLs
+ *
+ * After new notices are saved, we check their text for URLs. If there
+ * are URLs, we test each URL to see if it supports any
+ *
+ * @category Plugin
+ * @package Laconica
+ * @author Evan Prodromou <evan@controlyourself.ca>
+ * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link http://laconi.ca/
+ *
+ * @see Event
+ */
+
+class LinkbackPlugin extends Plugin
+{
+ var $notice = null;
+
+ function __construct()
+ {
+ parent::__construct();
+ }
+
+ function onEndNoticeSave($notice)
+ {
+ if ($notice->is_local == 1) {
+ // Try to avoid actually mucking with the
+ // notice content
+ $c = $notice->content;
+ $this->notice = $notice;
+ // Ignoring results
+ common_replace_urls_callback($c,
+ array($this, 'linkbackUrl'));
+ }
+ return true;
+ }
+
+ function linkbackUrl($url)
+ {
+ $orig = $url;
+ $url = htmlspecialchars_decode($orig);
+ $scheme = parse_url($url, PHP_URL_SCHEME);
+ if (!in_array($scheme, array('http', 'https'))) {
+ return $orig;
+ }
+
+ // XXX: Do a HEAD first to save some time/bandwidth
+
+ $fetcher = Auth_Yadis_Yadis::getHTTPFetcher();
+
+ $result = $fetcher->get($url,
+ array('User-Agent: ' . $this->userAgent(),
+ 'Accept: application/html+xml,text/html'));
+
+ if (!in_array($result->status, array('200', '206'))) {
+ return $orig;
+ }
+
+ if (array_key_exists('X-Pingback', $result->headers)) {
+ $endpoint = $result->headers['X-Pingback'];
+ } else if (preg_match('/<link rel="pingback" href="([^"]+)" ?/?>/',
+ $result->body,
+ $match)) {
+ $endpoint = $match[1];
+ } else {
+ // XXX: do Trackback lookup
+ return $orig;
+ }
+
+ $this->pingback($url, $endpoint);
+ return $orig;
+ }
+
+ function pingback($url, $endpoint)
+ {
+ $args = array($this->notice->uri, $url);
+
+ $request = xmlrpc_encode_request('pingback.ping', $args);
+ $context = stream_context_create(array('http' => array('method' => "POST",
+ 'header' =>
+ "Content-Type: text/xml\r\n".
+ "User-Agent: " . $this->userAgent(),
+ 'content' => $request)));
+ $file = file_get_contents($endpoint, false, $context);
+ $response = xmlrpc_decode($file);
+ if (xmlrpc_is_fault($response)) {
+ common_log(LOG_WARNING,
+ "Pingback error for '$url' ($endpoint): ".
+ "$response[faultString] ($response[faultCode])");
+ } else {
+ common_log(LOG_INFO,
+ "Pingback success for '$url' ($endpoint): ".
+ "'$response'");
+ }
+ }
+
+ function userAgent()
+ {
+ return 'LinkbackPlugin/'.LINKBACKPLUGIN_VERSION .
+ ' Laconica/' . LACONICA_VERSION;
+ }
+}