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Diffstat (limited to 'lib/oembedhelper.php')
| -rw-r--r-- | lib/oembedhelper.php | 318 |
1 files changed, 318 insertions, 0 deletions
diff --git a/lib/oembedhelper.php b/lib/oembedhelper.php new file mode 100644 index 000000000..84cf10586 --- /dev/null +++ b/lib/oembedhelper.php @@ -0,0 +1,318 @@ +<?php +/* + * StatusNet - the distributed open-source microblogging tool + * Copyright (C) 2008-2010, StatusNet, Inc. + * + * 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/>. + */ + +if (!defined('STATUSNET')) { + exit(1); +} + + +/** + * Utility class to wrap basic oEmbed lookups. + * + * Blacklisted hosts will use an alternate lookup method: + * - Twitpic + * + * Whitelisted hosts will use known oEmbed 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'. + */ +class oEmbedHelper +{ + protected static $apiMap = array( + 'flickr.com' => 'http://www.flickr.com/services/oembed/', + 'yfrog.com' => 'http://www.yfrog.com/api/oembed', + ); + protected static $functionMap = array( + 'twitpic.com' => 'oEmbedHelper::twitPic', + ); + + /** + * 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 oohembed.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 + * @param array $params + * @return object + */ + public static function getObject($url, $params=array()) + { + $host = parse_url($url, PHP_URL_HOST); + if (substr($host, 0, 4) == 'www.') { + $host = substr($host, 4); + } + + // Blacklist: systems with no oEmbed API of their own, which are + // either missing from or broken on oohembed.com's proxy. + // we know how to look data up in another way... + if (array_key_exists($host, self::$functionMap)) { + $func = self::$functionMap[$host]; + return call_user_func($func, $url, $params); + } + + // Whitelist: known API endpoints for sites that don't provide discovery... + if (array_key_exists($host, self::$apiMap)) { + $api = self::$apiMap[$host]; + } else { + try { + $api = self::discover($url); + } catch (Exception $e) { + // Discovery failed... fall back to oohembed if enabled. + $oohembed = common_config('oohembed', 'endpoint'); + if ($oohembed) { + $api = $oohembed; + } else { + throw $e; + } + } + } + return self::getObjectFrom($api, $url, $params); + } + + /** + * Perform basic discovery. + * @return string + */ + static function discover($url) + { + // @fixme ideally skip this for non-HTML stuff! + $body = self::http($url); + return self::discoverFromHTML($url, $body); + } + + /** + * Partially ripped from OStatus' FeedDiscovery class. + * + * @param string $url source URL, used to resolve relative links + * @param string $body HTML body text + * @return mixed string with URL or false if no target found + */ + static function discoverFromHTML($url, $body) + { + // DOMDocument::loadHTML may throw warnings on unrecognized elements, + // and notices on unrecognized namespaces. + $old = error_reporting(error_reporting() & ~(E_WARNING | E_NOTICE)); + $dom = new DOMDocument(); + $ok = $dom->loadHTML($body); + error_reporting($old); + + if (!$ok) { + throw new oEmbedHelper_BadHtmlException(); + } + + // Ok... now on to the links! + $feeds = array( + 'application/json+oembed' => false, + ); + + $nodes = $dom->getElementsByTagName('link'); + for ($i = 0; $i < $nodes->length; $i++) { + $node = $nodes->item($i); + if ($node->hasAttributes()) { + $rel = $node->attributes->getNamedItem('rel'); + $type = $node->attributes->getNamedItem('type'); + $href = $node->attributes->getNamedItem('href'); + if ($rel && $type && $href) { + $rel = array_filter(explode(" ", $rel->value)); + $type = trim($type->value); + $href = trim($href->value); + + if (in_array('alternate', $rel) && array_key_exists($type, $feeds) && empty($feeds[$type])) { + // Save the first feed found of each type... + $feeds[$type] = $href; + } + } + } + } + + // Return the highest-priority feed found + foreach ($feeds as $type => $url) { + if ($url) { + return $url; + } + } + + throw new oEmbedHelper_DiscoveryException(); + } + + /** + * Actually do an oEmbed lookup to a particular API endpoint. + * + * @param string $api oEmbed API endpoint URL + * @param string $url target URL to look up info about + * @param array $params + * @return object + */ + static function getObjectFrom($api, $url, $params=array()) + { + $params['url'] = $url; + $params['format'] = 'json'; + $data = self::json($api, $params); + return self::normalize($data); + } + + /** + * Normalize oEmbed format. + * + * @param object $orig + * @return object + */ + static function normalize($orig) + { + $data = clone($orig); + + 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('attachments', 'thumb_width'); + $data->thumbnail_height = common_config('attachments', 'thumb_height'); + } + } + + return $data; + } + + /** + * Using a local function for twitpic lookups, as oohembed's adapter + * doesn't return a valid result: + * http://code.google.com/p/oohembed/issues/detail?id=19 + * + * This code fetches metadata from Twitpic's own API, and attempts + * to guess proper thumbnail size from the original's size. + * + * @todo respect maxwidth and maxheight params + * + * @param string $url + * @param array $params + * @return object + */ + static function twitPic($url, $params=array()) + { + $matches = array(); + if (preg_match('!twitpic\.com/(\w+)!', $url, $matches)) { + $id = $matches[1]; + } else { + throw new Exception("Invalid twitpic URL"); + } + + // Grab metadata from twitpic's API... + // http://dev.twitpic.com/docs/2/media_show + $data = self::json('http://api.twitpic.com/2/media/show.json', + array('id' => $id)); + $oembed = (object)array('type' => 'photo', + 'url' => 'http://twitpic.com/show/full/' . $data->short_id, + 'width' => $data->width, + 'height' => $data->height); + if (!empty($data->message)) { + $oembed->title = $data->message; + } + + // Thumbnail is cropped and scaled to 150x150 box: + // http://dev.twitpic.com/docs/thumbnails/ + $thumbSize = 150; + $oembed->thumbnail_url = 'http://twitpic.com/show/thumb/' . $data->short_id; + $oembed->thumbnail_width = $thumbSize; + $oembed->thumbnail_height = $thumbSize; + + return $oembed; + } + + /** + * Fetch some URL and return JSON data. + * + * @param string $url + * @param array $params query-string params + * @return object + */ + static protected function json($url, $params=array()) + { + $data = self::http($url, $params); + return json_decode($data); + } + + /** + * Hit some web API and return data on success. + * @param string $url + * @param array $params + * @return string + */ + static protected function http($url, $params=array()) + { + $client = HTTPClient::start(); + if ($params) { + $query = http_build_query($params, null, '&'); + if (strpos($url, '?') === false) { + $url .= '?' . $query; + } else { + $url .= '&' . $query; + } + } + $response = $client->get($url); + if ($response->isOk()) { + return $response->getBody(); + } else { + throw new Exception('Bad HTTP response code: ' . $response->getStatus()); + } + } +} + +class oEmbedHelper_Exception extends Exception +{ +} + +class oEmbedHelper_BadHtmlException extends oEmbedHelper_Exception +{ + function __construct($previous=null) + { + return parent::__construct('Bad HTML in discovery data.', 0, $previous); + } +} + +class oEmbedHelper_DiscoveryException extends oEmbedHelper_Exception +{ + function __construct($previous=null) + { + return parent::__construct('No oEmbed discovery data.', 0, $previous); + } +} |