src/Protocol/ActivityPub/Receiver.php

   1 <?php
   2 /**
   3  * @file src/Protocol/ActivityPub/Receiver.php
   4  */
   5 namespace Friendica\Protocol\ActivityPub;
   6
   7 use Friendica\Database\DBA;
   8 use Friendica\Util\HTTPSignature;
   9 use Friendica\Core\Protocol;
  10 use Friendica\Model\Contact;
  11 use Friendica\Model\APContact;
  12 use Friendica\Model\Item;
  13 use Friendica\Model\User;
  14 use Friendica\Util\JsonLD;
  15 use Friendica\Util\LDSignature;
  16 use Friendica\Protocol\ActivityPub;
  17
  18 /**
  19  * @brief ActivityPub Receiver Protocol class
  20  *
  21  * To-Do:
  22  * - Update (Image, Video, Article, Note)
  23  * - Event
  24  * - Undo Announce
  25  *
  26  * Check what this is meant to do:
  27  * - Add
  28  * - Block
  29  * - Flag
  30  * - Remove
  31  * - Undo Block
  32  * - Undo Accept (Problem: This could invert a contact accept or an event accept)
  33  *
  34  * General:
  35  * - Possibly using the LD-JSON parser
  36  */
  37 class Receiver
  38 {
  39         const PUBLIC_COLLECTION = 'as:Public';
  40         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  41         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image'];
  42         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  43
  44         /**
  45          * Checks if the web request is done for the AP protocol
  46          *
  47          * @return is it AP?
  48          */
  49         public static function isRequest()
  50         {
  51                 return stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json') ||
  52                         stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/ld+json');
  53         }
  54
  55         /**
  56          * Checks incoming message from the inbox
  57          *
  58          * @param $body
  59          * @param $header
  60          * @param integer $uid User ID
  61          */
  62         public static function processInbox($body, $header, $uid)
  63         {
  64                 $http_signer = HTTPSignature::getSigner($body, $header);
  65                 if (empty($http_signer)) {
  66                         logger('Invalid HTTP signature, message will be discarded.', LOGGER_DEBUG);
  67                         return;
  68                 } else {
  69                         logger('HTTP signature is signed by ' . $http_signer, LOGGER_DEBUG);
  70                 }
  71
  72                 $activity = json_decode($body, true);
  73
  74                 if (empty($activity)) {
  75                         logger('Invalid body.', LOGGER_DEBUG);
  76                         return;
  77                 }
  78
  79                 $ldactivity = JsonLD::compact($activity);
  80
  81                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor');
  82
  83                 logger('Message for user ' . $uid . ' is from actor ' . $actor, LOGGER_DEBUG);
  84
  85                 if (LDSignature::isSigned($activity)) {
  86                         $ld_signer = LDSignature::getSigner($activity);
  87                         if (empty($ld_signer)) {
  88                                 logger('Invalid JSON-LD signature from ' . $actor, LOGGER_DEBUG);
  89                         }
  90                         if (!empty($ld_signer && ($actor == $http_signer))) {
  91                                 logger('The HTTP and the JSON-LD signature belong to ' . $ld_signer, LOGGER_DEBUG);
  92                                 $trust_source = true;
  93                         } elseif (!empty($ld_signer)) {
  94                                 logger('JSON-LD signature is signed by ' . $ld_signer, LOGGER_DEBUG);
  95                                 $trust_source = true;
  96                         } elseif ($actor == $http_signer) {
  97                                 logger('Bad JSON-LD signature, but HTTP signer fits the actor.', LOGGER_DEBUG);
  98                                 $trust_source = true;
  99                         } else {
 100                                 logger('Invalid JSON-LD signature and the HTTP signer is different.', LOGGER_DEBUG);
 101                                 $trust_source = false;
 102                         }
 103                 } elseif ($actor == $http_signer) {
 104                         logger('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', LOGGER_DEBUG);
 105                         $trust_source = true;
 106                 } else {
 107                         logger('No JSON-LD signature, different actor.', LOGGER_DEBUG);
 108                         $trust_source = false;
 109                 }
 110
 111                 self::processActivity($activity, $ldactivity, $body, $uid, $trust_source);
 112         }
 113
 114         /**
 115          *
 116          *
 117          * @param array $activity
 118          * @param integer $uid User ID
 119          * @param $trust_source
 120          *
 121          * @return
 122          */
 123         private static function prepareObjectData($activity, $ldactivity, $uid, &$trust_source)
 124         {
 125                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor');
 126                 if (empty($actor)) {
 127                         logger('Empty actor', LOGGER_DEBUG);
 128                         return [];
 129                 }
 130
 131                 $type = JsonLD::fetchElement($ldactivity, '@type');
 132
 133                 // Fetch all receivers from to, cc, bto and bcc
 134                 $receivers = self::getReceivers($ldactivity, $actor);
 135
 136                 // When it is a delivery to a personal inbox we add that user to the receivers
 137                 if (!empty($uid)) {
 138                         $owner = User::getOwnerDataById($uid);
 139                         $additional = ['uid:' . $uid => $uid];
 140                         $receivers = array_merge($receivers, $additional);
 141                 }
 142
 143                 logger('Receivers: ' . json_encode($receivers), LOGGER_DEBUG);
 144
 145                 $object_id = JsonLD::fetchElement($ldactivity, 'as:object');
 146                 if (empty($object_id)) {
 147                         logger('No object found', LOGGER_DEBUG);
 148                         return [];
 149                 }
 150
 151                 // Fetch the content only on activities where this matters
 152                 if (in_array($type, ['as:Create', 'as:Announce'])) {
 153                         $object_data = self::fetchObject($object_id, $activity['object'], $ldactivity['as:object'], $trust_source);
 154                         if (empty($object_data)) {
 155                                 logger("Object data couldn't be processed", LOGGER_DEBUG);
 156                                 return [];
 157                         }
 158                         // We had been able to retrieve the object data - so we can trust the source
 159                         $trust_source = true;
 160                 } elseif (in_array($type, ['as:Like', 'as:Dislike'])) {
 161                         // Create a mostly empty array out of the activity data (instead of the object).
 162                         // This way we later don't have to check for the existence of ech individual array element.
 163                         $object_data = self::processObject($ldactivity);
 164                         $object_data['name'] = $type;
 165                         $object_data['author'] = JsonLD::fetchElement($ldactivity, 'as:actor');
 166                         $object_data['object'] = $object_id;
 167                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 168                 } else {
 169                         $object_data = [];
 170                         $object_data['id'] = JsonLD::fetchElement($ldactivity, '@id');
 171                         $object_data['object'] = $activity['object'];
 172                         $object_data['object_type'] = JsonLD::fetchElement($ldactivity, 'as:object', '@type');
 173                 }
 174
 175                 $object_data = self::addActivityFields($object_data, $activity);
 176
 177                 $object_data['type'] = $activity['type'];
 178                 $object_data['owner'] = $actor;
 179                 $object_data['receiver'] = array_merge(defaults($object_data, 'receiver', []), $receivers);
 180
 181                 logger('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], LOGGER_DEBUG);
 182
 183                 return $object_data;
 184         }
 185
 186         /**
 187          *
 188          *
 189          * @param array $activity
 190          * @param $body
 191          * @param integer $uid User ID
 192          * @param $trust_source
 193          */
 194         public static function processActivity($activity, $ldactivity = '', $body = '', $uid = null, $trust_source = false)
 195         {
 196                 if (empty($ldactivity)) {
 197                         $ldactivity = JsonLD::compact($activity);
 198                 }
 199
 200                 $type = JsonLD::fetchElement($ldactivity, '@type');
 201                 if (!$type) {
 202                         logger('Empty type', LOGGER_DEBUG);
 203                         return;
 204                 }
 205
 206                 if (!JsonLD::fetchElement($ldactivity, 'as:object')) {
 207                         logger('Empty object', LOGGER_DEBUG);
 208                         return;
 209                 }
 210
 211                 if (!JsonLD::fetchElement($ldactivity, 'as:actor')) {
 212                         logger('Empty actor', LOGGER_DEBUG);
 213                         return;
 214
 215                 }
 216
 217                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 218                 $object_data = self::prepareObjectData($activity, $ldactivity, $uid, $trust_source);
 219                 if (empty($object_data)) {
 220                         logger('No object data found', LOGGER_DEBUG);
 221                         return;
 222                 }
 223
 224                 if (!$trust_source) {
 225                         logger('No trust for activity type "' . $type . '", so we quit now.', LOGGER_DEBUG);
 226                         return;
 227                 }
 228
 229                 switch ($type) {
 230                         case 'as:Create':
 231                         case 'as:Announce':
 232                                 ActivityPub\Processor::createItem($object_data, $body);
 233                                 break;
 234
 235                         case 'as:Like':
 236                                 ActivityPub\Processor::likeItem($object_data, $body);
 237                                 break;
 238
 239                         case 'as:Dislike':
 240                                 ActivityPub\Processor::dislikeItem($object_data, $body);
 241                                 break;
 242
 243                         case 'as:Update':
 244                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 245                                         /// @todo
 246                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 247                                         ActivityPub\Processor::updatePerson($object_data, $body);
 248                                 }
 249                                 break;
 250
 251                         case 'as:Delete':
 252                                 if ($object_data['object_type'] == 'as:Tombstone') {
 253                                         ActivityPub\Processor::deleteItem($object_data, $body);
 254                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 255                                         ActivityPub\Processor::deletePerson($object_data, $body);
 256                                 }
 257                                 break;
 258
 259                         case 'as:Follow':
 260                                 ActivityPub\Processor::followUser($object_data);
 261                                 break;
 262
 263                         case 'as:Accept':
 264                                 if ($object_data['object_type'] == 'as:Follow') {
 265                                         ActivityPub\Processor::acceptFollowUser($object_data);
 266                                 }
 267                                 break;
 268
 269                         case 'as:Reject':
 270                                 if ($object_data['object_type'] == 'as:Follow') {
 271                                         ActivityPub\Processor::rejectFollowUser($object_data);
 272                                 }
 273                                 break;
 274
 275                         case 'as:Undo':
 276                                 if ($object_data['object_type'] == 'as:Follow') {
 277                                         ActivityPub\Processor::undoFollowUser($object_data);
 278                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES)) {
 279                                         ActivityPub\Processor::undoActivity($object_data);
 280                                 }
 281                                 break;
 282
 283                         default:
 284                                 logger('Unknown activity: ' . $type, LOGGER_DEBUG);
 285                                 break;
 286                 }
 287         }
 288
 289         /**
 290          * Fetch the receiver list from an activity array
 291          *
 292          * @param array $activity
 293          * @param string $actor
 294          *
 295          * @return array with receivers (user id)
 296          */
 297         private static function getReceivers($activity, $actor)
 298         {
 299                 $receivers = [];
 300
 301                 // When it is an answer, we inherite the receivers from the parent
 302                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo');
 303                 if (!empty($replyto)) {
 304                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 305                         while ($parent = Item::fetch($parents)) {
 306                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 307                         }
 308                 }
 309
 310                 if (!empty($actor)) {
 311                         $profile = APContact::getByURL($actor);
 312                         $followers = defaults($profile, 'followers', '');
 313
 314                         logger('Actor: ' . $actor . ' - Followers: ' . $followers, LOGGER_DEBUG);
 315                 } else {
 316                         logger('Empty actor', LOGGER_DEBUG);
 317                         $followers = '';
 318                 }
 319
 320                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 321                         $receiver_list = JsonLD::fetchElementArray($activity, $element);
 322                         if (empty($receiver_list)) {
 323                                 continue;
 324                         }
 325
 326                         foreach ($receiver_list as $receiver) {
 327                                 if ($receiver == self::PUBLIC_COLLECTION) {
 328                                         $receivers['uid:0'] = 0;
 329                                 }
 330
 331                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 332                                         // This will most likely catch all OStatus connections to Mastodon
 333                                         $condition = ['alias' => [$actor, normalise_link($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 334                                                 , 'archive' => false, 'pending' => false];
 335                                         $contacts = DBA::select('contact', ['uid'], $condition);
 336                                         while ($contact = DBA::fetch($contacts)) {
 337                                                 if ($contact['uid'] != 0) {
 338                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 339                                                 }
 340                                         }
 341                                         DBA::close($contacts);
 342                                 }
 343
 344                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 345                                         $condition = ['nurl' => normalise_link($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 346                                                 'network' => Protocol::ACTIVITYPUB, 'archive' => false, 'pending' => false];
 347                                         $contacts = DBA::select('contact', ['uid'], $condition);
 348                                         while ($contact = DBA::fetch($contacts)) {
 349                                                 if ($contact['uid'] != 0) {
 350                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 351                                                 }
 352                                         }
 353                                         DBA::close($contacts);
 354                                         continue;
 355                                 }
 356
 357                                 $condition = ['self' => true, 'nurl' => normalise_link($receiver)];
 358                                 $contact = DBA::selectFirst('contact', ['uid'], $condition);
 359                                 if (!DBA::isResult($contact)) {
 360                                         continue;
 361                                 }
 362                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 363                         }
 364                 }
 365
 366                 self::switchContacts($receivers, $actor);
 367
 368                 return $receivers;
 369         }
 370
 371         /**
 372          * Switches existing contacts to ActivityPub
 373          *
 374          * @param integer $cid Contact ID
 375          * @param integer $uid User ID
 376          * @param string $url Profile URL
 377          */
 378         private static function switchContact($cid, $uid, $url)
 379         {
 380                 $profile = ActivityPub::probeProfile($url);
 381                 if (empty($profile)) {
 382                         return;
 383                 }
 384
 385                 logger('Switch contact ' . $cid . ' (' . $profile['url'] . ') for user ' . $uid . ' to ActivityPub');
 386
 387                 $photo = $profile['photo'];
 388                 unset($profile['photo']);
 389                 unset($profile['baseurl']);
 390
 391                 $profile['nurl'] = normalise_link($profile['url']);
 392                 DBA::update('contact', $profile, ['id' => $cid]);
 393
 394                 Contact::updateAvatar($photo, $uid, $cid);
 395
 396                 // Send a new follow request to be sure that the connection still exists
 397                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND]])) {
 398                         ActivityPub\Transmitter::sendActivity('Follow', $profile['url'], $uid);
 399                         logger('Send a new follow request to ' . $profile['url'] . ' for user ' . $uid, LOGGER_DEBUG);
 400                 }
 401         }
 402
 403         /**
 404          *
 405          *
 406          * @param $receivers
 407          * @param $actor
 408          */
 409         private static function switchContacts($receivers, $actor)
 410         {
 411                 if (empty($actor)) {
 412                         return;
 413                 }
 414
 415                 foreach ($receivers as $receiver) {
 416                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => normalise_link($actor)]);
 417                         if (DBA::isResult($contact)) {
 418                                 self::switchContact($contact['id'], $receiver, $actor);
 419                         }
 420
 421                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [normalise_link($actor), $actor]]);
 422                         if (DBA::isResult($contact)) {
 423                                 self::switchContact($contact['id'], $receiver, $actor);
 424                         }
 425                 }
 426         }
 427
 428         /**
 429          *
 430          *
 431          * @param $object_data
 432          * @param array $activity
 433          *
 434          * @return
 435          */
 436         private static function addActivityFields($object_data, $activity)
 437         {
 438                 if (!empty($activity['published']) && empty($object_data['published'])) {
 439                         $object_data['published'] = $activity['published'];
 440                 }
 441
 442                 if (!empty($activity['updated']) && empty($object_data['updated'])) {
 443                         $object_data['updated'] = $activity['updated'];
 444                 }
 445
 446                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 447                         $object_data['diaspora:guid'] = $activity['diaspora:guid'];
 448                 }
 449
 450                 if (!empty($activity['inReplyTo']) && empty($object_data['parent-uri'])) {
 451                         $object_data['parent-uri'] = JsonLD::fetchElement($activity, 'inReplyTo', 'id');
 452                 }
 453
 454                 if (!empty($activity['instrument'])) {
 455                         $object_data['service'] = JsonLD::fetchElement($activity, 'instrument', 'name', 'type', 'Service');
 456                 }
 457                 return $object_data;
 458         }
 459
 460         /**
 461          *
 462          *
 463          * @param $object_id
 464          * @param $object
 465          * @param $trust_source
 466          *
 467          * @return array with object data
 468          */
 469         private static function fetchObject($object_id, $object = [], $ldobject = [], $trust_source = false)
 470         {
 471                 if (!$trust_source || is_string($object)) {
 472                         $data = ActivityPub::fetchContent($object_id);
 473                         if (empty($data)) {
 474                                 logger('Empty content for ' . $object_id . ', check if content is available locally.', LOGGER_DEBUG);
 475                                 $data = $object_id;
 476                         } else {
 477                                 $ldobject = JsonLD::compact($data);
 478                                 logger('Fetched content for ' . $object_id, LOGGER_DEBUG);
 479                         }
 480                 } else {
 481                         logger('Using original object for url ' . $object_id, LOGGER_DEBUG);
 482                         $data = $object;
 483                 }
 484
 485                 if (is_string($data)) {
 486                         $item = Item::selectFirst([], ['uri' => $data]);
 487                         if (!DBA::isResult($item)) {
 488                                 logger('Object with url ' . $data . ' was not found locally.', LOGGER_DEBUG);
 489                                 return false;
 490                         }
 491                         logger('Using already stored item for url ' . $object_id, LOGGER_DEBUG);
 492                         $data = ActivityPub\Transmitter::createNote($item);
 493                         $ldobject = JsonLD::compact($data);
 494                 }
 495
 496                 if (empty($data['type'])) {
 497                         logger('Empty type', LOGGER_DEBUG);
 498                         return false;
 499                 }
 500
 501                 if (in_array($data['type'], ActivityPub::CONTENT_TYPES)) {
 502                         return self::processObject($ldobject);
 503                 }
 504
 505                 if ($data['type'] == 'Announce') {
 506                         if (empty($data['object'])) {
 507                                 return false;
 508                         }
 509                         return self::fetchObject($data['object']);
 510                 }
 511
 512                 logger('Unhandled object type: ' . $data['type'], LOGGER_DEBUG);
 513         }
 514
 515         /**
 516          * Convert tags from JSON-LD format into a simplified format
 517          *
 518          * @param array $tags Tags in JSON-LD format
 519          *
 520          * @return array with tags in a simplified format
 521          */
 522         private static function processTags($tags)
 523         {
 524                 $taglist = [];
 525                 foreach ($tags as $tag) {
 526                         $taglist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 527                                 'href' => JsonLD::fetchElement($tag, 'as:href'),
 528                                 'name' => JsonLD::fetchElement($tag, 'as:name')];
 529                 }
 530                 return $taglist;
 531         }
 532
 533         /**
 534          * Convert attachments from JSON-LD format into a simplified format
 535          *
 536          * @param array $attachments Attachments in JSON-LD format
 537          *
 538          * @return array with attachmants in a simplified format
 539          */
 540         private static function processAttachments($attachments)
 541         {
 542                 $attachlist = [];
 543                 foreach ($attachments as $attachment) {
 544                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 545                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType'),
 546                                 'name' => JsonLD::fetchElement($attachment, 'as:name'),
 547                                 'url' => JsonLD::fetchElement($attachment, 'as:url')];
 548                 }
 549                 return $attachlist;
 550         }
 551
 552         /**
 553          * Fetches data from the object part of an activity
 554          *
 555          * @param array $object
 556          *
 557          * @return array
 558          */
 559         private static function processObject($object)
 560         {
 561                 if (!JsonLD::fetchElement($object, '@id')) {
 562                         return false;
 563                 }
 564
 565                 $object_data = [];
 566                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 567                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 568
 569                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo');
 570
 571                 if (empty($object_data['reply-to-id'])) {
 572                         $object_data['reply-to-id'] = $object_data['id'];
 573                 }
 574
 575                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 576                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 577
 578                 if (empty($object_data['updated'])) {
 579                         $object_data['updated'] = $object_data['published'];
 580                 }
 581
 582                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 583                         $object_data['published'] = $object_data['updated'];
 584                 }
 585
 586                 $actor = JsonLD::fetchElement($object, 'as:attributedTo');
 587                 if (empty($actor)) {
 588                         $actor = JsonLD::fetchElement($object, 'as:actor');
 589                 }
 590
 591                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid');
 592                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment');
 593                 $object_data['owner'] = $object_data['author'] = $actor;
 594                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context');
 595                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation');
 596                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 597                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name');
 598                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary');
 599                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content');
 600                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 601                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
 602                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
 603                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
 604 //              $object_data['service'] = JsonLD::fetchElement($object, 'instrument', 'name', 'type', 'Service'); // todo
 605                 $object_data['service'] = null;
 606                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url');
 607
 608                 // Special treatment for Hubzilla links
 609                 if (is_array($object_data['alternate-url'])) {
 610                         if (!empty($object['as:url'])) {
 611                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href');
 612                         } else {
 613                                 $object_data['alternate-url'] = null;
 614                         }
 615                 }
 616
 617                 $object_data['receiver'] = self::getReceivers($object, $object_data['owner']);
 618
 619                 // Common object data:
 620
 621                 // Unhandled
 622                 // @context, type, actor, signature, mediaType, duration, replies, icon
 623
 624                 // Also missing: (Defined in the standard, but currently unused)
 625                 // audience, preview, endTime, startTime, generator, image
 626
 627                 // Data in Notes:
 628
 629                 // Unhandled
 630                 // contentMap, announcement_count, announcements, context_id, likes, like_count
 631                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
 632
 633                 // Data in video:
 634
 635                 // To-Do?
 636                 // category, licence, language, commentsEnabled
 637
 638                 // Unhandled
 639                 // views, waitTranscoding, state, support, subtitleLanguage
 640                 // likes, dislikes, shares, comments
 641
 642                 return $object_data;
 643         }
 644 }