gnu-social/plugins/Embed/lib/embedhelper.php

193 lines
6.7 KiB
PHP

<?php
// This file is part of GNU social - https://www.gnu.org/software/social
//
// GNU social 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.
//
// GNU social 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 GNU social. If not, see <http://www.gnu.org/licenses/>.
/**
* OembedPlugin implementation for GNU social
*
* @package GNUsocial
* @author Mikael Nordfeldth
* @author hannes
* @author Diogo Cordeiro <diogo@fc.up.pt>
* @copyright 2019 Free Software Foundation, Inc http://www.fsf.org
* @license https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
*/
defined('GNUSOCIAL') || die();
/**
* Utility class to wrap basic embed lookups.
*
* Blacklisted hosts will use an alternate lookup method:
* - Twitpic
*
* Whitelisted hosts will use known embed API endpoints:
* - Flickr, YFrog
*
* Sites that provide discovery links will use them directly; a bug
* in use of discovery links with query strings is worked around.
*
* Others will fall back to oohembed (unless disabled).
* The API endpoint can be configured or disabled through config
* as 'oohembed'/'endpoint'.
*
* @copyright 2019 Free Software Foundation, Inc http://www.fsf.org
* @license https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
*/
class EmbedHelper
{
/**
* Perform or fake an oEmbed lookup for the given resource.
*
* Some known hosts are whitelisted with API endpoints where we
* know they exist but autodiscovery data isn't available.
* If autodiscovery links are missing and we don't recognize the
* host, we'll pass it to noembed.com's public service which
* will either proxy or fake info on a lot of sites.
*
* A few hosts are blacklisted due to known problems with oohembed,
* in which case we'll look up the info another way and return
* equivalent data.
*
* Throws exceptions on failure.
*
* @param string $url
* @return object
* @throws EmbedHelper_BadHtmlException
* @throws HTTP_Request2_Exception
*/
public static function getObject($url)
{
common_log(LOG_INFO, 'Checking for remote URL metadata for ' . $url);
// TODO: Make this class something like UrlMetadata, or use a dataobject?
$metadata = new stdClass();
if (Event::handle('GetRemoteUrlMetadata', array($url, &$metadata))) {
// If that event didn't return anything, try downloading the body and parse it
// don't use quickGet since we want to check Content-Type header for utf-8
$client = new HTTPClient();
$response = $client->get($url);
if (!$response->isOk()) {
// TRANS: Exception. %s is the URL we tried to GET.
throw new Exception(sprintf(_m('Could not GET URL %s.'), $url), $response->getStatus());
}
$body = $response->getBody();
// DOMDocument::loadHTML may throw warnings on unrecognized elements,
// and notices on unrecognized namespaces.
$old = error_reporting(error_reporting() & ~(E_WARNING | E_NOTICE));
// DOMDocument assumes ISO-8859-1 per HTML spec
// use UTF-8 if we find any evidence of that encoding
$utf8_evidence = false;
$unicode_check_dom = new DOMDocument();
$ok = $unicode_check_dom->loadHTML($body);
if (!$ok) {
throw new EmbedHelper_BadHtmlException();
}
$metaNodes = $unicode_check_dom->getElementsByTagName('meta');
foreach ($metaNodes as $metaNode) {
// case in-sensitive since Content-type and utf-8 can be written in many ways
if (stristr($metaNode->getAttribute('http-equiv'), 'content-type')
&& stristr($metaNode->getAttribute('content'), 'utf-8')) {
$utf8_evidence = true;
break;
} elseif (stristr($metaNode->getAttribute('charset'), 'utf-8')) {
$utf8_evidence = true;
break;
}
}
unset($unicode_check_dom);
// The Content-Type HTTP response header overrides encoding metatags in DOM
if (stristr($response->getHeader('Content-Type'), 'utf-8')) {
$utf8_evidence = true;
}
// add utf-8 encoding prolog if we have reason to believe this is utf-8 content
// DOMDocument('1.0', 'UTF-8') does not work!
$utf8_tag = $utf8_evidence ? '<?xml encoding="utf-8" ?>' : '';
$dom = new DOMDocument();
$ok = $dom->loadHTML($utf8_tag.$body);
unset($body); // storing the DOM in memory is enough...
error_reporting($old);
if (!$ok) {
throw new EmbedHelper_BadHtmlException();
}
Event::handle('GetRemoteUrlMetadataFromDom', array($url, $dom, &$metadata));
}
return self::normalize($metadata);
}
/**
* Normalize oEmbed format.
*
* @param stdClass $data
* @return object
* @throws Exception
*/
public static function normalize(stdClass $data)
{
if (empty($data->type)) {
throw new Exception('Invalid oEmbed data: no type field.');
}
if ($data->type == 'image') {
// YFrog does this.
$data->type = 'photo';
}
if (isset($data->thumbnail_url)) {
if (!isset($data->thumbnail_width)) {
// !?!?!
$data->thumbnail_width = common_config('thumbnail', 'width');
$data->thumbnail_height = common_config('thumbnail', 'height');
}
}
return $data;
}
}
class EmbedHelper_Exception extends Exception
{
public function __construct($message = "", $code = 0, $previous = null)
{
parent::__construct($message, $code, $previous);
}
}
class EmbedHelper_BadHtmlException extends EmbedHelper_Exception
{
public function __construct($previous=null)
{
return parent::__construct('Bad HTML in discovery data.', 0, $previous);
}
}
class EmbedHelper_DiscoveryException extends EmbedHelper_Exception
{
public function __construct($previous=null)
{
return parent::__construct('No oEmbed discovery data.', 0, $previous);
}
}