gnu-social/plugins/LinkbackPlugin.php

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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 $orig;
}
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$pb = null;
$tb = null;
if (array_key_exists('X-Pingback', $result->headers)) {
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$pb = $result->headers['X-Pingback'];
} else if (preg_match('/<link rel="pingback" href="([^"]+)" ?/?>/',
$result->body,
$match)) {
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$pb = $match[1];
}
$tb = $this->getTrackback($result->body, $result->final_url);
if (!empty($tb)) {
$this->trackback($result->final_url, $tb);
} else if (!empty($pb)) {
$this->pingback($result->final_url, $pb);
}
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'");
}
}
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// Largely cadged from trackback_cls.php by
// Ran Aroussi <ran@blogish.org>, GPL2
// http://phptrackback.sourceforge.net/
function getTrackback($text, $url)
{
if (preg_match_all('/(<rdf:RDF.*?<\/rdf:RDF>)/sm', $text, $match, PREG_SET_ORDER)) {
for ($i = 0; $i < count($match); $i++) {
if (preg_match('|dc:identifier="' . preg_quote($url) . '"|ms', $match[$i][1])) {
$rdf_array[] = trim($match[$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]);
break;
}
}
}
// Return Trackbacks
if (empty($tb_array)) {
return null;
} else {
return $tb_array[0];
}
}
if (preg_match_all('/(<a[^>]*?rel=[\'"]trackback[\'"][^>]*?>)/', $text, $match)) {
foreach ($match[1] as $atag) {
if (preg_match('/href=[\'"]([^\'"]*?)[\'"]/', $atag, $url)) {
return $url[1];
}
}
}
return null;
}
function trackback($url, $endpoint)
{
$profile = $this->notice->getProfile();
$args = array('title' => sprintf(_('%1$s\'s status on %2$s'),
$profile->nickname,
common_exact_date($this->notice->created)),
'excerpt' => $this->notice->content,
'url' => $this->notice->uri,
'blog_name' => $profile->nickname);
$fetcher = Auth_Yadis_Yadis::getHTTPFetcher();
$result = $fetcher->post($endpoint,
http_build_query($args),
array('User-Agent: ' . $this->userAgent()));
if ($result->status != '200') {
common_log(LOG_WARNING,
"Trackback error for '$url' ($endpoint): ".
"$result->body");
} else {
common_log(LOG_INFO,
"Trackback success for '$url' ($endpoint): ".
"'$result->body'");
}
}
function userAgent()
{
return 'LinkbackPlugin/'.LINKBACKPLUGIN_VERSION .
' Laconica/' . LACONICA_VERSION;
}
}