src/Protocol/ActivityPub/Receiver.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2020, Friendica
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Protocol\ActivityPub;
  23
  24 use Friendica\Content\Text\BBCode;
  25 use Friendica\Database\DBA;
  26 use Friendica\Content\Text\HTML;
  27 use Friendica\Content\Text\Markdown;
  28 use Friendica\Core\Logger;
  29 use Friendica\Core\Protocol;
  30 use Friendica\Model\Contact;
  31 use Friendica\Model\APContact;
  32 use Friendica\Model\Item;
  33 use Friendica\Model\User;
  34 use Friendica\Protocol\Activity;
  35 use Friendica\Protocol\ActivityPub;
  36 use Friendica\Util\HTTPSignature;
  37 use Friendica\Util\JsonLD;
  38 use Friendica\Util\LDSignature;
  39 use Friendica\Util\Strings;
  40
  41 /**
  42  * ActivityPub Receiver Protocol class
  43  *
  44  * To-Do:
  45  * @todo Undo Announce
  46  *
  47  * Check what this is meant to do:
  48  * - Add
  49  * - Block
  50  * - Flag
  51  * - Remove
  52  * - Undo Block
  53  */
  54 class Receiver
  55 {
  56         const PUBLIC_COLLECTION = 'as:Public';
  57         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  58         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event', 'as:Audio'];
  59         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  60
  61         const TARGET_UNKNOWN = 0;
  62         const TARGET_TO = 1;
  63         const TARGET_CC = 2;
  64         const TARGET_BTO = 3;
  65         const TARGET_BCC = 4;
  66         const TARGET_FOLLOWER = 5;
  67         const TARGET_ANSWER = 6;
  68         const TARGET_GLOBAL = 7;
  69
  70         /**
  71          * Checks if the web request is done for the AP protocol
  72          *
  73          * @return bool is it AP?
  74          */
  75         public static function isRequest()
  76         {
  77                 return stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/activity+json') ||
  78                         stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/ld+json');
  79         }
  80
  81         /**
  82          * Checks incoming message from the inbox
  83          *
  84          * @param         $body
  85          * @param         $header
  86          * @param integer $uid User ID
  87          * @throws \Exception
  88          */
  89         public static function processInbox($body, $header, $uid)
  90         {
  91                 $activity = json_decode($body, true);
  92                 if (empty($activity)) {
  93                         Logger::warning('Invalid body.');
  94                         return;
  95                 }
  96
  97                 $ldactivity = JsonLD::compact($activity);
  98
  99                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor', '@id');
 100
 101                 $apcontact = APContact::getByURL($actor);
 102                 if (!empty($apcontact) && ($apcontact['type'] == 'Application') && ($apcontact['nick'] == 'relay')) {
 103                         self::processRelayPost($ldactivity, $actor);
 104                         return;
 105                 }
 106
 107                 $http_signer = HTTPSignature::getSigner($body, $header);
 108                 if (empty($http_signer)) {
 109                         Logger::warning('Invalid HTTP signature, message will be discarded.');
 110                         return;
 111                 } else {
 112                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
 113                 }
 114
 115                 $signer = [$http_signer];
 116
 117                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
 118
 119                 if (LDSignature::isSigned($activity)) {
 120                         $ld_signer = LDSignature::getSigner($activity);
 121                         if (empty($ld_signer)) {
 122                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
 123                         } elseif ($ld_signer != $http_signer) {
 124                                 $signer[] = $ld_signer;
 125                         }
 126                         if (!empty($ld_signer && ($actor == $http_signer))) {
 127                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
 128                                 $trust_source = true;
 129                         } elseif (!empty($ld_signer)) {
 130                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
 131                                 $trust_source = true;
 132                         } elseif ($actor == $http_signer) {
 133                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
 134                                 $trust_source = true;
 135                         } else {
 136                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
 137                                 $trust_source = false;
 138                         }
 139                 } elseif ($actor == $http_signer) {
 140                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
 141                         $trust_source = true;
 142                 } else {
 143                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
 144                         $trust_source = false;
 145                 }
 146
 147                 self::processActivity($ldactivity, $body, $uid, $trust_source, true, $signer);
 148         }
 149
 150         /**
 151          * Process incoming posts from relays
 152          *
 153          * @param array  $activity
 154          * @param string $actor
 155          * @return void
 156          */
 157         private static function processRelayPost(array $activity, string $actor)
 158         {
 159                 $type = JsonLD::fetchElement($activity, '@type');
 160                 if (!$type) {
 161                         Logger::info('Empty type', ['activity' => $activity]);
 162                         return;
 163                 }
 164
 165                 if ($type != 'as:Announce') {
 166                         Logger::info('Not an announcement', ['activity' => $activity]);
 167                         return;
 168                 }
 169
 170                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 171                 if (empty($object_id)) {
 172                         Logger::info('No object id found', ['activity' => $activity]);
 173                         return;
 174                 }
 175
 176                 $contact = Contact::getByURL($actor);
 177                 if (empty($contact)) {
 178                         Logger::info('Relay contact not found', ['actor' => $actor]);
 179                         return;
 180                 }
 181
 182                 if (!in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 183                         Logger::notice('Relay is no sharer', ['actor' => $actor]);
 184                         return;
 185                 }
 186
 187                 Logger::info('Got relayed message id', ['id' => $object_id]);
 188
 189                 $item_id = Item::searchByLink($object_id);
 190                 if ($item_id) {
 191                         Logger::info('Relayed message already exists', ['id' => $object_id, 'item' => $item_id]);
 192                         return;
 193                 }
 194
 195                 $id = Processor::fetchMissingActivity($object_id, [], $actor);
 196                 if (empty($id)) {
 197                         Logger::notice('Relayed message had not been fetched', ['id' => $object_id]);
 198                         return;
 199                 }
 200
 201                 $item_id = Item::searchByLink($object_id);
 202                 if ($item_id) {
 203                         Logger::info('Relayed message had been fetched and stored', ['id' => $object_id, 'item' => $item_id]);
 204                 } else {
 205                         Logger::notice('Relayed message had not been stored', ['id' => $object_id]);
 206                 }
 207         }
 208
 209         /**
 210          * Fetches the object type for a given object id
 211          *
 212          * @param array   $activity
 213          * @param string  $object_id Object ID of the the provided object
 214          * @param integer $uid       User ID
 215          *
 216          * @return string with object type
 217          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 218          * @throws \ImagickException
 219          */
 220         private static function fetchObjectType($activity, $object_id, $uid = 0)
 221         {
 222                 if (!empty($activity['as:object'])) {
 223                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 224                         if (!empty($object_type)) {
 225                                 return $object_type;
 226                         }
 227                 }
 228
 229                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 230                         // We just assume "note" since it doesn't make a difference for the further processing
 231                         return 'as:Note';
 232                 }
 233
 234                 $profile = APContact::getByURL($object_id);
 235                 if (!empty($profile['type'])) {
 236                         return 'as:' . $profile['type'];
 237                 }
 238
 239                 $data = ActivityPub::fetchContent($object_id, $uid);
 240                 if (!empty($data)) {
 241                         $object = JsonLD::compact($data);
 242                         $type = JsonLD::fetchElement($object, '@type');
 243                         if (!empty($type)) {
 244                                 return $type;
 245                         }
 246                 }
 247
 248                 return null;
 249         }
 250
 251         /**
 252          * Prepare the object array
 253          *
 254          * @param array   $activity     Array with activity data
 255          * @param integer $uid          User ID
 256          * @param boolean $push         Message had been pushed to our system
 257          * @param boolean $trust_source Do we trust the source?
 258          *
 259          * @return array with object data
 260          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 261          * @throws \ImagickException
 262          */
 263         public static function prepareObjectData($activity, $uid, $push, &$trust_source)
 264         {
 265                 $id = JsonLD::fetchElement($activity, '@id');
 266                 if (!empty($id) && !$trust_source) {
 267                         $fetched_activity = ActivityPub::fetchContent($id, $uid ?? 0);
 268                         if (!empty($fetched_activity)) {
 269                                 $object = JsonLD::compact($fetched_activity);
 270                                 $fetched_id = JsonLD::fetchElement($object, '@id');
 271                                 if ($fetched_id == $id) {
 272                                         Logger::info('Activity had been fetched successfully', ['id' => $id]);
 273                                         $trust_source = true;
 274                                         $activity = $object;
 275                                 } else {
 276                                         Logger::info('Activity id is not equal', ['id' => $id, 'fetched' => $fetched_id]);
 277                                 }
 278                         } else {
 279                                 Logger::info('Activity could not been fetched', ['id' => $id]);
 280                         }
 281                 }
 282
 283                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 284                 if (empty($actor)) {
 285                         Logger::info('Empty actor', ['activity' => $activity]);
 286                         return [];
 287                 }
 288
 289                 $type = JsonLD::fetchElement($activity, '@type');
 290
 291                 // Fetch all receivers from to, cc, bto and bcc
 292                 $receiverdata = self::getReceivers($activity, $actor);
 293                 $receivers = $reception_types = [];
 294                 foreach ($receiverdata as $key => $data) {
 295                         $receivers[$key] = $data['uid'];
 296                         $reception_types[$data['uid']] = $data['type'] ?? self::TARGET_UNKNOWN;
 297                 }
 298
 299                 // When it is a delivery to a personal inbox we add that user to the receivers
 300                 if (!empty($uid)) {
 301                         $additional = [$uid => $uid];
 302                         $receivers = array_replace($receivers, $additional);
 303                         if (empty($activity['thread-completion']) && (empty($reception_types[$uid]) || in_array($reception_types[$uid], [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL]))) {
 304                                 $reception_types[$uid] = self::TARGET_BCC;
 305                         }
 306                 } else {
 307                         // We possibly need some user to fetch private content,
 308                         // so we fetch the first out ot the list.
 309                         $uid = self::getFirstUserFromReceivers($receivers);
 310                 }
 311
 312                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 313                 if (empty($object_id)) {
 314                         Logger::log('No object found', Logger::DEBUG);
 315                         return [];
 316                 }
 317
 318                 if (!is_string($object_id)) {
 319                         Logger::info('Invalid object id', ['object' => $object_id]);
 320                         return [];
 321                 }
 322
 323                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
 324
 325                 // Fetch the content only on activities where this matters
 326                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 327                         // Always fetch on "Announce"
 328                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source && ($type != 'as:Announce'), $uid);
 329                         if (empty($object_data)) {
 330                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
 331                                 return [];
 332                         }
 333
 334                         $object_data['object_id'] = $object_id;
 335
 336                         if ($type == 'as:Announce') {
 337                                 $object_data['push'] = false;
 338                         } else {
 339                                 $object_data['push'] = $push;
 340                         }
 341
 342                         // Test if it is an answer to a mail
 343                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 344                                 $object_data['directmessage'] = true;
 345                         } else {
 346                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 347                         }
 348                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 349                         // Create a mostly empty array out of the activity data (instead of the object).
 350                         // This way we later don't have to check for the existence of ech individual array element.
 351                         $object_data = self::processObject($activity);
 352                         $object_data['name'] = $type;
 353                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 354                         $object_data['object_id'] = $object_id;
 355                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 356                 } elseif (in_array($type, ['as:Add'])) {
 357                         $object_data = [];
 358                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 359                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 360                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 361                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 362                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 363                 } else {
 364                         $object_data = [];
 365                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 366                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 367                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 368                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 369                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 370
 371                         // An Undo is done on the object of an object, so we need that type as well
 372                         if (($type == 'as:Undo') && !empty($object_data['object_object'])) {
 373                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 374                         }
 375                 }
 376
 377                 $object_data = self::addActivityFields($object_data, $activity);
 378
 379                 if (empty($object_data['object_type'])) {
 380                         $object_data['object_type'] = $object_type;
 381                 }
 382
 383                 $object_data['type'] = $type;
 384                 $object_data['actor'] = $actor;
 385                 $object_data['item_receiver'] = $receivers;
 386                 $object_data['receiver'] = array_replace($object_data['receiver'] ?? [], $receivers);
 387                 $object_data['reception_type'] = array_replace($object_data['reception_type'] ?? [], $reception_types);
 388
 389                 $author = $object_data['author'] ?? $actor;
 390                 if (!empty($author) && !empty($object_data['id'])) {
 391                         $author_host = parse_url($author, PHP_URL_HOST);
 392                         $id_host = parse_url($object_data['id'], PHP_URL_HOST);
 393                         if ($author_host == $id_host) {
 394                                 Logger::info('Valid hosts', ['type' => $type, 'host' => $id_host]);
 395                         } else {
 396                                 Logger::notice('Differing hosts on author and id', ['type' => $type, 'author' => $author_host, 'id' => $id_host]);
 397                                 $trust_source = false;
 398                         }
 399                 }
 400
 401                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 402
 403                 return $object_data;
 404         }
 405
 406         /**
 407          * Fetches the first user id from the receiver array
 408          *
 409          * @param array $receivers Array with receivers
 410          * @return integer user id;
 411          */
 412         public static function getFirstUserFromReceivers($receivers)
 413         {
 414                 foreach ($receivers as $receiver) {
 415                         if (!empty($receiver)) {
 416                                 return $receiver;
 417                         }
 418                 }
 419                 return 0;
 420         }
 421
 422         /**
 423          * Processes the activity object
 424          *
 425          * @param array   $activity     Array with activity data
 426          * @param string  $body
 427          * @param integer $uid          User ID
 428          * @param boolean $trust_source Do we trust the source?
 429          * @param boolean $push         Message had been pushed to our system
 430          * @throws \Exception
 431          */
 432         public static function processActivity($activity, string $body = '', int $uid = null, bool $trust_source = false, bool $push = false, array $signer = [])
 433         {
 434                 $type = JsonLD::fetchElement($activity, '@type');
 435                 if (!$type) {
 436                         Logger::info('Empty type', ['activity' => $activity]);
 437                         return;
 438                 }
 439
 440                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 441                         Logger::info('Empty object', ['activity' => $activity]);
 442                         return;
 443                 }
 444
 445                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 446                 if (empty($actor)) {
 447                         Logger::info('Empty actor', ['activity' => $activity]);
 448                         return;
 449                 }
 450
 451                 if (is_array($activity['as:object'])) {
 452                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 453                 } else {
 454                         $attributed_to = '';
 455                 }
 456
 457                 // Test the provided signatures against the actor and "attributedTo"
 458                 if ($trust_source) {
 459                         if (!empty($attributed_to) && !empty($actor)) {
 460                                 $trust_source = (in_array($actor, $signer) && in_array($attributed_to, $signer));
 461                         } else {
 462                                 $trust_source = in_array($actor, $signer);
 463                         }
 464                 }
 465
 466                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 467                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
 468                 if (empty($object_data)) {
 469                         Logger::info('No object data found', ['activity' => $activity]);
 470                         return;
 471                 }
 472
 473                 if (!$trust_source) {
 474                         Logger::info('Activity trust could not be achieved.',  ['id' => $object_data['object_id'], 'type' => $type, 'signer' => $signer, 'actor' => $actor, 'attributedTo' => $attributed_to]);
 475                         return;
 476                 }
 477
 478                 if (!empty($body) && empty($object_data['raw'])) {
 479                         $object_data['raw'] = $body;
 480                 }
 481
 482                 // Internal flag for thread completion. See Processor.php
 483                 if (!empty($activity['thread-completion'])) {
 484                         $object_data['thread-completion'] = $activity['thread-completion'];
 485                 }
 486
 487                 // Internal flag for posts that arrived via relay
 488                 if (!empty($activity['from-relay'])) {
 489                         $object_data['from-relay'] = $activity['from-relay'];
 490                 }
 491
 492                 switch ($type) {
 493                         case 'as:Create':
 494                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 495                                         $item = ActivityPub\Processor::createItem($object_data);
 496                                         ActivityPub\Processor::postItem($object_data, $item);
 497                                 }
 498                                 break;
 499
 500                         case 'as:Add':
 501                                 if ($object_data['object_type'] == 'as:tag') {
 502                                         ActivityPub\Processor::addTag($object_data);
 503                                 }
 504                                 break;
 505
 506                         case 'as:Announce':
 507                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 508                                         $object_data['thread-completion'] = Contact::getIdForURL($actor);
 509
 510                                         $item = ActivityPub\Processor::createItem($object_data);
 511                                         if (empty($item)) {
 512                                                 return;
 513                                         }
 514
 515                                         $item['post-type'] = Item::PT_ANNOUNCEMENT;
 516                                         ActivityPub\Processor::postItem($object_data, $item);
 517
 518                                         $announce_object_data = self::processObject($activity);
 519                                         $announce_object_data['name'] = $type;
 520                                         $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 521                                         $announce_object_data['object_id'] = $object_data['object_id'];
 522                                         $announce_object_data['object_type'] = $object_data['object_type'];
 523                                         $announce_object_data['push'] = $push;
 524
 525                                         if (!empty($body)) {
 526                                                 $announce_object_data['raw'] = $body;
 527                                         }
 528
 529                                         ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 530                                 }
 531                                 break;
 532
 533                         case 'as:Like':
 534                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 535                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 536                                 }
 537                                 break;
 538
 539                         case 'as:Dislike':
 540                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 541                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 542                                 }
 543                                 break;
 544
 545                         case 'as:TentativeAccept':
 546                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 547                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 548                                 }
 549                                 break;
 550
 551                         case 'as:Update':
 552                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 553                                         ActivityPub\Processor::updateItem($object_data);
 554                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 555                                         ActivityPub\Processor::updatePerson($object_data);
 556                                 }
 557                                 break;
 558
 559                         case 'as:Delete':
 560                                 if ($object_data['object_type'] == 'as:Tombstone') {
 561                                         ActivityPub\Processor::deleteItem($object_data);
 562                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 563                                         ActivityPub\Processor::deletePerson($object_data);
 564                                 }
 565                                 break;
 566
 567                         case 'as:Follow':
 568                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 569                                         ActivityPub\Processor::followUser($object_data);
 570                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 571                                         $object_data['reply-to-id'] = $object_data['object_id'];
 572                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 573                                 }
 574                                 break;
 575
 576                         case 'as:Accept':
 577                                 if ($object_data['object_type'] == 'as:Follow') {
 578                                         ActivityPub\Processor::acceptFollowUser($object_data);
 579                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 580                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 581                                 }
 582                                 break;
 583
 584                         case 'as:Reject':
 585                                 if ($object_data['object_type'] == 'as:Follow') {
 586                                         ActivityPub\Processor::rejectFollowUser($object_data);
 587                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 588                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 589                                 }
 590                                 break;
 591
 592                         case 'as:Undo':
 593                                 if (($object_data['object_type'] == 'as:Follow') &&
 594                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 595                                         ActivityPub\Processor::undoFollowUser($object_data);
 596                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 597                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 598                                         ActivityPub\Processor::rejectFollowUser($object_data);
 599                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 600                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 601                                         ActivityPub\Processor::undoActivity($object_data);
 602                                 }
 603                                 break;
 604
 605                         default:
 606                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 607                                 break;
 608                 }
 609         }
 610
 611         /**
 612          * Fetch the receiver list from an activity array
 613          *
 614          * @param array   $activity
 615          * @param string  $actor
 616          * @param array   $tags
 617          * @param boolean $fetch_unlisted
 618          *
 619          * @return array with receivers (user id)
 620          * @throws \Exception
 621          */
 622         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 623         {
 624                 $reply = $receivers = [];
 625
 626                 // When it is an answer, we inherite the receivers from the parent
 627                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 628                 if (!empty($replyto)) {
 629                         $reply = [$replyto];
 630
 631                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 632                         $fixedReplyTo = Item::getURIByLink($replyto);
 633                         if (!empty($fixedReplyTo)) {
 634                                 $reply[] = $fixedReplyTo;
 635                         }
 636                 }
 637
 638                 // Fetch all posts that refer to the object id
 639                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 640                 if (!empty($object_id)) {
 641                         $reply[] = $object_id;
 642                 }
 643
 644                 if (!empty($reply)) {
 645                         $parents = Item::select(['uid'], ['uri' => $reply]);
 646                         while ($parent = Item::fetch($parents)) {
 647                                 $receivers[$parent['uid']] = ['uid' => $parent['uid'], 'type' => self::TARGET_ANSWER];
 648                         }
 649                 }
 650
 651                 if (!empty($actor)) {
 652                         $profile = APContact::getByURL($actor);
 653                         $followers = $profile['followers'] ?? '';
 654
 655                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 656                 } else {
 657                         Logger::info('Empty actor', ['activity' => $activity]);
 658                         $followers = '';
 659                 }
 660
 661                 // We have to prevent false follower assumptions upon thread completions
 662                 $follower_target = empty($activity['thread-completion']) ? self::TARGET_FOLLOWER : self::TARGET_UNKNOWN;
 663
 664                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 665                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 666                         if (empty($receiver_list)) {
 667                                 continue;
 668                         }
 669
 670                         foreach ($receiver_list as $receiver) {
 671                                 if ($receiver == self::PUBLIC_COLLECTION) {
 672                                         $receivers[0] = ['uid' => 0, 'type' => self::TARGET_GLOBAL];
 673                                 }
 674
 675                                 // Add receiver "-1" for unlisted posts
 676                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 677                                         $receivers[-1] = ['uid' => -1, 'type' => self::TARGET_GLOBAL];
 678                                 }
 679
 680                                 // Fetch the receivers for the public and the followers collection
 681                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 682                                         $receivers = self::getReceiverForActor($actor, $tags, $receivers, $follower_target);
 683                                         continue;
 684                                 }
 685
 686                                 // Fetching all directly addressed receivers
 687                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 688                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 689                                 if (!DBA::isResult($contact)) {
 690                                         continue;
 691                                 }
 692
 693                                 // Check if the potential receiver is following the actor
 694                                 // Exception: The receiver is targetted via "to" or this is a comment
 695                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 696                                         $networks = Protocol::FEDERATED;
 697                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 698                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 699
 700                                         // Forum posts are only accepted from forum contacts
 701                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 702                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 703                                         }
 704
 705                                         if (!DBA::exists('contact', $condition)) {
 706                                                 continue;
 707                                         }
 708                                 }
 709
 710                                 $type = $receivers[$contact['uid']]['type'] ?? self::TARGET_UNKNOWN;
 711                                 if (in_array($type, [self::TARGET_UNKNOWN, self::TARGET_FOLLOWER, self::TARGET_ANSWER, self::TARGET_GLOBAL])) {
 712                                         switch ($element) {
 713                                                 case 'as:to':
 714                                                         $type = self::TARGET_TO;
 715                                                         break;
 716                                                 case 'as:cc':
 717                                                         $type = self::TARGET_CC;
 718                                                         break;
 719                                                 case 'as:bto':
 720                                                         $type = self::TARGET_BTO;
 721                                                         break;
 722                                                 case 'as:bcc':
 723                                                         $type = self::TARGET_BCC;
 724                                                         break;
 725                                         }
 726
 727                                         $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $type];
 728                                 }
 729                         }
 730                 }
 731
 732                 self::switchContacts($receivers, $actor);
 733
 734                 return $receivers;
 735         }
 736
 737         /**
 738          * Fetch the receiver list of a given actor
 739          *
 740          * @param string  $actor
 741          * @param array   $tags
 742          * @param array   $receivers
 743          * @param integer $target_type
 744          *
 745          * @return array with receivers (user id)
 746          * @throws \Exception
 747          */
 748         private static function getReceiverForActor($actor, $tags, $receivers, $target_type)
 749         {
 750                 $basecondition = ['rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 751                         'network' => Protocol::FEDERATED, 'archive' => false, 'pending' => false];
 752
 753                 $condition = DBA::mergeConditions($basecondition, ["`nurl` = ? AND `uid` != ?", Strings::normaliseLink($actor), 0]);
 754                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 755                 while ($contact = DBA::fetch($contacts)) {
 756                         if (empty($receivers[$contact['uid']]) && self::isValidReceiverForActor($contact, $tags)) {
 757                                 $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $target_type];
 758                         }
 759                 }
 760                 DBA::close($contacts);
 761
 762                 // The queries are split because of performance issues
 763                 $condition = DBA::mergeConditions($basecondition, ["`alias` IN (?, ?) AND `uid` != ?", Strings::normaliseLink($actor), $actor, 0]);
 764                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 765                 while ($contact = DBA::fetch($contacts)) {
 766                         if (empty($receivers[$contact['uid']]) && self::isValidReceiverForActor($contact, $tags)) {
 767                                 $receivers[$contact['uid']] = ['uid' => $contact['uid'], 'type' => $target_type];
 768                         }
 769                 }
 770                 DBA::close($contacts);
 771                 return $receivers;
 772         }
 773
 774         /**
 775          * Tests if the contact is a valid receiver for this actor
 776          *
 777          * @param array  $contact
 778          * @param string $actor
 779          * @param array  $tags
 780          *
 781          * @return bool with receivers (user id)
 782          * @throws \Exception
 783          */
 784         private static function isValidReceiverForActor($contact, $tags)
 785         {
 786                 // Are we following the contact? Then this is a valid receiver
 787                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 788                         return true;
 789                 }
 790
 791                 // When the possible receiver isn't a community, then it is no valid receiver
 792                 $owner = User::getOwnerDataById($contact['uid']);
 793                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 794                         return false;
 795                 }
 796
 797                 // Is the community account tagged?
 798                 foreach ($tags as $tag) {
 799                         if ($tag['type'] != 'Mention') {
 800                                 continue;
 801                         }
 802
 803                         if (Strings::compareLink($tag['href'], $owner['url'])) {
 804                                 return true;
 805                         }
 806                 }
 807
 808                 return false;
 809         }
 810
 811         /**
 812          * Switches existing contacts to ActivityPub
 813          *
 814          * @param integer $cid Contact ID
 815          * @param integer $uid User ID
 816          * @param string  $url Profile URL
 817          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 818          * @throws \ImagickException
 819          */
 820         public static function switchContact($cid, $uid, $url)
 821         {
 822                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 823                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 824                         return;
 825                 }
 826
 827                 if (Contact::updateFromProbe($cid)) {
 828                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 829                 }
 830
 831                 // Send a new follow request to be sure that the connection still exists
 832                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 833                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 834                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 835                 }
 836         }
 837
 838         /**
 839          *
 840          *
 841          * @param $receivers
 842          * @param $actor
 843          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 844          * @throws \ImagickException
 845          */
 846         private static function switchContacts($receivers, $actor)
 847         {
 848                 if (empty($actor)) {
 849                         return;
 850                 }
 851
 852                 foreach ($receivers as $receiver) {
 853                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 854                         if (DBA::isResult($contact)) {
 855                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 856                         }
 857
 858                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver['uid'], 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 859                         if (DBA::isResult($contact)) {
 860                                 self::switchContact($contact['id'], $receiver['uid'], $actor);
 861                         }
 862                 }
 863         }
 864
 865         /**
 866          *
 867          *
 868          * @param       $object_data
 869          * @param array $activity
 870          *
 871          * @return mixed
 872          */
 873         private static function addActivityFields($object_data, $activity)
 874         {
 875                 if (!empty($activity['published']) && empty($object_data['published'])) {
 876                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 877                 }
 878
 879                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 880                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 881                 }
 882
 883                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 884                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 885
 886                 if (!empty($object_data['object_id'])) {
 887                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 888                         $objectId = Item::getURIByLink($object_data['object_id']);
 889                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
 890                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
 891                                 $object_data['object_id'] = $objectId;
 892                         }
 893                 }
 894
 895                 return $object_data;
 896         }
 897
 898         /**
 899          * Fetches the object data from external ressources if needed
 900          *
 901          * @param string  $object_id    Object ID of the the provided object
 902          * @param array   $object       The provided object array
 903          * @param boolean $trust_source Do we trust the provided object?
 904          * @param integer $uid          User ID for the signature that we use to fetch data
 905          *
 906          * @return array|false with trusted and valid object data
 907          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 908          * @throws \ImagickException
 909          */
 910         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
 911         {
 912                 // By fetching the type we check if the object is complete.
 913                 $type = JsonLD::fetchElement($object, '@type');
 914
 915                 if (!$trust_source || empty($type)) {
 916                         $data = ActivityPub::fetchContent($object_id, $uid);
 917                         if (!empty($data)) {
 918                                 $object = JsonLD::compact($data);
 919                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 920                         } else {
 921                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 922
 923                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 924                                 if (!DBA::isResult($item)) {
 925                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 926                                         return false;
 927                                 }
 928                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 929                                 $data = ActivityPub\Transmitter::createNote($item);
 930                                 $object = JsonLD::compact($data);
 931                         }
 932
 933                         $id = JsonLD::fetchElement($object, '@id');
 934                         if (empty($id)) {
 935                                 Logger::info('Empty id');
 936                                 return false;
 937                         }
 938
 939                         if ($id != $object_id) {
 940                                 Logger::info('Fetched id differs from provided id', ['provided' => $object_id, 'fetched' => $id]);
 941                                 return false;
 942                         }
 943                 } else {
 944                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 945                 }
 946
 947                 $type = JsonLD::fetchElement($object, '@type');
 948                 if (empty($type)) {
 949                         Logger::info('Empty type');
 950                         return false;
 951                 }
 952
 953                 // We currently don't handle 'pt:CacheFile', but with this step we avoid logging
 954                 if (in_array($type, self::CONTENT_TYPES) || ($type == 'pt:CacheFile')) {
 955                         $object_data = self::processObject($object);
 956
 957                         if (!empty($data)) {
 958                                 $object_data['raw'] = json_encode($data);
 959                         }
 960                         return $object_data;
 961                 }
 962
 963                 if ($type == 'as:Announce') {
 964                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
 965                         if (empty($object_id) || !is_string($object_id)) {
 966                                 return false;
 967                         }
 968                         return self::fetchObject($object_id, [], false, $uid);
 969                 }
 970
 971                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 972                 return false;
 973         }
 974
 975         /**
 976          * Convert tags from JSON-LD format into a simplified format
 977          *
 978          * @param array $tags Tags in JSON-LD format
 979          *
 980          * @return array with tags in a simplified format
 981          */
 982         public static function processTags(array $tags)
 983         {
 984                 $taglist = [];
 985
 986                 foreach ($tags as $tag) {
 987                         if (empty($tag)) {
 988                                 continue;
 989                         }
 990
 991                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 992                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
 993                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
 994
 995                         if (empty($element['type'])) {
 996                                 continue;
 997                         }
 998
 999                         if (empty($element['href'])) {
1000                                 $element['href'] = $element['name'];
1001                         }
1002
1003                         $taglist[] = $element;
1004                 }
1005                 return $taglist;
1006         }
1007
1008         /**
1009          * Convert emojis from JSON-LD format into a simplified format
1010          *
1011          * @param array $emojis
1012          * @return array with emojis in a simplified format
1013          */
1014         private static function processEmojis(array $emojis)
1015         {
1016                 $emojilist = [];
1017
1018                 foreach ($emojis as $emoji) {
1019                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
1020                                 continue;
1021                         }
1022
1023                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
1024                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
1025                                 'href' => $url];
1026
1027                         $emojilist[] = $element;
1028                 }
1029
1030                 return $emojilist;
1031         }
1032
1033         /**
1034          * Convert attachments from JSON-LD format into a simplified format
1035          *
1036          * @param array $attachments Attachments in JSON-LD format
1037          *
1038          * @return array Attachments in a simplified format
1039          */
1040         private static function processAttachments(array $attachments)
1041         {
1042                 $attachlist = [];
1043
1044                 // Removes empty values
1045                 $attachments = array_filter($attachments);
1046
1047                 foreach ($attachments as $attachment) {
1048                         switch (JsonLD::fetchElement($attachment, '@type')) {
1049                                 case 'as:Page':
1050                                         $pageUrl = null;
1051                                         $pageImage = null;
1052
1053                                         $urls = JsonLD::fetchElementArray($attachment, 'as:url');
1054                                         foreach ($urls as $url) {
1055                                                 // Single scalar URL case
1056                                                 if (is_string($url)) {
1057                                                         $pageUrl = $url;
1058                                                         continue;
1059                                                 }
1060
1061                                                 $href = JsonLD::fetchElement($url, 'as:href', '@id');
1062                                                 $mediaType = JsonLD::fetchElement($url, 'as:mediaType', '@value');
1063                                                 if (Strings::startsWith($mediaType, 'image')) {
1064                                                         $pageImage = $href;
1065                                                 } else {
1066                                                         $pageUrl = $href;
1067                                                 }
1068                                         }
1069
1070                                         $attachlist[] = [
1071                                                 'type'  => 'link',
1072                                                 'title' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1073                                                 'desc'  => JsonLD::fetchElement($attachment, 'as:summary', '@value'),
1074                                                 'url'   => $pageUrl,
1075                                                 'image' => $pageImage,
1076                                         ];
1077                                         break;
1078                                 case 'as:Link':
1079                                         $attachlist[] = [
1080                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1081                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
1082                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1083                                                 'url' => JsonLD::fetchElement($attachment, 'as:href', '@id')
1084                                         ];
1085                                         break;
1086                                 case 'as:Image':
1087                                         $mediaType = JsonLD::fetchElement($attachment, 'as:mediaType', '@value');
1088                                         $imageFullUrl = JsonLD::fetchElement($attachment, 'as:url', '@id');
1089                                         $imagePreviewUrl = null;
1090                                         // Multiple URLs?
1091                                         if (!$imageFullUrl && ($urls = JsonLD::fetchElementArray($attachment, 'as:url'))) {
1092                                                 $imageVariants = [];
1093                                                 $previewVariants = [];
1094                                                 foreach ($urls as $url) {
1095                                                         // Scalar URL, no discrimination possible
1096                                                         if (is_string($url)) {
1097                                                                 $imageFullUrl = $url;
1098                                                                 continue;
1099                                                         }
1100
1101                                                         // Not sure what to do with a different Link media type than the base Image, we skip
1102                                                         if ($mediaType != JsonLD::fetchElement($url, 'as:mediaType', '@value')) {
1103                                                                 continue;
1104                                                         }
1105
1106                                                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1107
1108                                                         // Default URL choice if no discriminating width is provided
1109                                                         $imageFullUrl = $href ?? $imageFullUrl;
1110
1111                                                         $width = intval(JsonLD::fetchElement($url, 'as:width', '@value') ?? 1);
1112
1113                                                         if ($href && $width) {
1114                                                                 $imageVariants[$width] = $href;
1115                                                                 // 632 is the ideal width for full screen frio posts, we compute the absolute distance to it
1116                                                                 $previewVariants[abs(632 - $width)] = $href;
1117                                                         }
1118                                                 }
1119
1120                                                 if ($imageVariants) {
1121                                                         // Taking the maximum size image
1122                                                         ksort($imageVariants);
1123                                                         $imageFullUrl = array_pop($imageVariants);
1124
1125                                                         // Taking the minimum number distance to the target distance
1126                                                         ksort($previewVariants);
1127                                                         $imagePreviewUrl = array_shift($previewVariants);
1128                                                 }
1129
1130                                                 unset($imageVariants);
1131                                                 unset($previewVariants);
1132                                         }
1133
1134                                         $attachlist[] = [
1135                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1136                                                 'mediaType' => $mediaType,
1137                                                 'name'  => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1138                                                 'url'   => $imageFullUrl,
1139                                                 'image' => $imagePreviewUrl !== $imageFullUrl ? $imagePreviewUrl : null,
1140                                         ];
1141                                         break;
1142                                 default:
1143                                         $attachlist[] = [
1144                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
1145                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
1146                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
1147                                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')
1148                                         ];
1149                         }
1150                 }
1151
1152                 return $attachlist;
1153         }
1154
1155         /**
1156          * Fetch the original source or content with the "language" Markdown or HTML
1157          *
1158          * @param array $object
1159          * @param array $object_data
1160          *
1161          * @return array
1162          * @throws \Exception
1163          */
1164         private static function getSource($object, $object_data)
1165         {
1166                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
1167                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1168                 if (!empty($object_data['source'])) {
1169                         return $object_data;
1170                 }
1171
1172                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
1173                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1174                 if (!empty($object_data['source'])) {
1175                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
1176                         return $object_data;
1177                 }
1178
1179                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
1180                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
1181                 if (!empty($object_data['source'])) {
1182                         $object_data['source'] = HTML::toBBCode($object_data['source']);
1183                         return $object_data;
1184                 }
1185
1186                 return $object_data;
1187         }
1188
1189         /**
1190          * Check if the "as:url" element is an array with multiple links
1191          * This is the case with audio and video posts.
1192          * Then the links are added as attachments
1193          *
1194          * @param array $object      The raw object
1195          * @param array $object_data The parsed object data for later processing
1196          * @return array the object data
1197          */
1198         private static function processAttachmentUrls(array $object, array $object_data) {
1199                 // Check if this is some url with multiple links
1200                 if (empty($object['as:url'])) {
1201                         return $object_data;
1202                 }
1203
1204                 $urls = $object['as:url'];
1205                 $keys = array_keys($urls);
1206                 if (!is_numeric(array_pop($keys))) {
1207                         return $object_data;
1208                 }
1209
1210                 $attachments = [];
1211
1212                 foreach ($urls as $url) {
1213                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
1214                                 continue;
1215                         }
1216
1217                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1218                         if (empty($href)) {
1219                                 continue;
1220                         }
1221
1222                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
1223                         if (empty($mediatype)) {
1224                                 continue;
1225                         }
1226
1227                         if ($mediatype == 'text/html') {
1228                                 $object_data['alternate-url'] = $href;
1229                         }
1230
1231                         $filetype = strtolower(substr($mediatype, 0, strpos($mediatype, '/')));
1232
1233                         if ($filetype == 'audio') {
1234                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href, 'height' => null, 'size' => null];
1235                         } elseif ($filetype == 'video') {
1236                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1237                                 $size = (int)JsonLD::fetchElement($url, 'pt:size', '@value');
1238
1239                                 // We save bandwidth by using a moderate height (alt least 480 pixel height)
1240                                 // Peertube normally uses these heights: 240, 360, 480, 720, 1080
1241                                 if (!empty($attachments[$filetype]['height']) &&
1242                                         ($height > $attachments[$filetype]['height']) && ($attachments[$filetype]['height'] >= 480)) {
1243                                         continue;
1244                                 }
1245
1246                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href, 'height' => $height, 'size' => $size];
1247                         } elseif (in_array($mediatype, ['application/x-bittorrent', 'application/x-bittorrent;x-scheme-handler/magnet'])) {
1248                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1249
1250                                 // For Torrent links we always store the highest resolution
1251                                 if (!empty($attachments[$mediatype]['height']) && ($height < $attachments[$mediatype]['height'])) {
1252                                         continue;
1253                                 }
1254
1255                                 $attachments[$mediatype] = ['type' => $mediatype, 'url' => $href, 'height' => $height, 'size' => null];
1256                         }
1257                 }
1258
1259                 foreach ($attachments as $type => $attachment) {
1260                         $object_data['attachments'][] = ['type' => $type,
1261                                 'mediaType' => $attachment['type'],
1262                                 'height' => $attachment['height'],
1263                                 'size' => $attachment['size'],
1264                                 'name' => '',
1265                                 'url' => $attachment['url']];
1266                 }
1267                 return $object_data;
1268         }
1269
1270         /**
1271          * Fetches data from the object part of an activity
1272          *
1273          * @param array $object
1274          *
1275          * @return array
1276          * @throws \Exception
1277          */
1278         private static function processObject($object)
1279         {
1280                 if (!JsonLD::fetchElement($object, '@id')) {
1281                         return false;
1282                 }
1283
1284                 $object_data = [];
1285                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
1286                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
1287                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
1288
1289                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
1290                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
1291                         $object_data['reply-to-id'] = $object_data['id'];
1292                 } else {
1293                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
1294                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
1295                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
1296                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
1297                                 $object_data['reply-to-id'] = $replyToId;
1298                         }
1299                 }
1300
1301                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
1302                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
1303
1304                 if (empty($object_data['updated'])) {
1305                         $object_data['updated'] = $object_data['published'];
1306                 }
1307
1308                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
1309                         $object_data['published'] = $object_data['updated'];
1310                 }
1311
1312                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
1313                 if (empty($actor)) {
1314                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
1315                 }
1316
1317                 $location = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
1318                 $location = JsonLD::fetchElement($location, 'location', '@value');
1319                 if ($location) {
1320                         // Some AP software allow formatted text in post location, so we run all the text converters we have to boil
1321                         // down to HTML and then finally format to plaintext.
1322                         $location = Markdown::convert($location);
1323                         $location = BBCode::convert($location);
1324                         $location = HTML::toPlaintext($location);
1325                 }
1326
1327                 $object_data['sc:identifier'] = JsonLD::fetchElement($object, 'sc:identifier', '@value');
1328                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
1329                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
1330                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
1331                 $object_data['actor'] = $object_data['author'] = $actor;
1332                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
1333                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
1334                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
1335                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
1336                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
1337                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
1338                 $object_data = self::getSource($object, $object_data);
1339                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
1340                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
1341                 $object_data['location'] = $location;
1342                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
1343                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
1344                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
1345                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
1346                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment') ?? []);
1347                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag') ?? []);
1348                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', null, '@type', 'toot:Emoji') ?? []);
1349                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
1350                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
1351                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
1352
1353                 // Special treatment for Hubzilla links
1354                 if (is_array($object_data['alternate-url'])) {
1355                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
1356
1357                         if (!is_string($object_data['alternate-url'])) {
1358                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1359                         }
1360                 }
1361
1362                 if (in_array($object_data['object_type'], ['as:Audio', 'as:Video'])) {
1363                         $object_data = self::processAttachmentUrls($object, $object_data);
1364                 }
1365
1366                 $receiverdata = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1367                 $receivers = $reception_types = [];
1368                 foreach ($receiverdata as $key => $data) {
1369                         $receivers[$key] = $data['uid'];
1370                         $reception_types[$data['uid']] = $data['type'] ?? 0;
1371                 }
1372
1373                 $object_data['receiver'] = $receivers;
1374                 $object_data['reception_type'] = $reception_types;
1375
1376                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1377                 unset($object_data['receiver'][-1]);
1378                 unset($object_data['reception_type'][-1]);
1379
1380                 // Common object data:
1381
1382                 // Unhandled
1383                 // @context, type, actor, signature, mediaType, duration, replies, icon
1384
1385                 // Also missing: (Defined in the standard, but currently unused)
1386                 // audience, preview, endTime, startTime, image
1387
1388                 // Data in Notes:
1389
1390                 // Unhandled
1391                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1392                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1393
1394                 // Data in video:
1395
1396                 // To-Do?
1397                 // category, licence, language, commentsEnabled
1398
1399                 // Unhandled
1400                 // views, waitTranscoding, state, support, subtitleLanguage
1401                 // likes, dislikes, shares, comments
1402
1403                 return $object_data;
1404         }
1405 }