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\Core\Logger;
   9 use Friendica\Core\Protocol;
  10 use Friendica\Model\Contact;
  11 use Friendica\Model\APContact;
  12 use Friendica\Model\Conversation;
  13 use Friendica\Model\Item;
  14 use Friendica\Model\User;
  15 use Friendica\Protocol\ActivityPub;
  16 use Friendica\Util\DateTimeFormat;
  17 use Friendica\Util\HTTPSignature;
  18 use Friendica\Util\JsonLD;
  19 use Friendica\Util\LDSignature;
  20 use Friendica\Util\Strings;
  21
  22 /**
  23  * @brief ActivityPub Receiver Protocol class
  24  *
  25  * To-Do:
  26  * - Undo Announce
  27  *
  28  * Check what this is meant to do:
  29  * - Add
  30  * - Block
  31  * - Flag
  32  * - Remove
  33  * - Undo Block
  34  */
  35 class Receiver
  36 {
  37         const PUBLIC_COLLECTION = 'as:Public';
  38         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  39         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event'];
  40         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  41
  42         /**
  43          * Checks if the web request is done for the AP protocol
  44          *
  45          * @return bool is it AP?
  46          */
  47         public static function isRequest()
  48         {
  49                 return stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json') ||
  50                         stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/ld+json');
  51         }
  52
  53         /**
  54          * Checks incoming message from the inbox
  55          *
  56          * @param         $body
  57          * @param         $header
  58          * @param integer $uid User ID
  59          * @throws \Exception
  60          */
  61         public static function processInbox($body, $header, $uid)
  62         {
  63                 $http_signer = HTTPSignature::getSigner($body, $header);
  64                 if (empty($http_signer)) {
  65                         Logger::warning('Invalid HTTP signature, message will be discarded.');
  66                         return;
  67                 } else {
  68                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
  69                 }
  70
  71                 $activity = json_decode($body, true);
  72
  73                 if (empty($activity)) {
  74                         Logger::warning('Invalid body.');
  75                         return;
  76                 }
  77
  78                 $ldactivity = JsonLD::compact($activity);
  79
  80                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor');
  81
  82                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
  83
  84                 if (LDSignature::isSigned($activity)) {
  85                         $ld_signer = LDSignature::getSigner($activity);
  86                         if (empty($ld_signer)) {
  87                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
  88                         }
  89                         if (!empty($ld_signer && ($actor == $http_signer))) {
  90                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
  91                                 $trust_source = true;
  92                         } elseif (!empty($ld_signer)) {
  93                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
  94                                 $trust_source = true;
  95                         } elseif ($actor == $http_signer) {
  96                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
  97                                 $trust_source = true;
  98                         } else {
  99                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
 100                                 $trust_source = false;
 101                         }
 102                 } elseif ($actor == $http_signer) {
 103                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
 104                         $trust_source = true;
 105                 } else {
 106                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
 107                         $trust_source = false;
 108                 }
 109
 110                 self::processActivity($ldactivity, $body, $uid, $trust_source);
 111         }
 112
 113         /**
 114          * Fetches the object type for a given object id
 115          *
 116          * @param array   $activity
 117          * @param string  $object_id Object ID of the the provided object
 118          * @param integer $uid       User ID
 119          *
 120          * @return string with object type
 121          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 122          * @throws \ImagickException
 123          */
 124         private static function fetchObjectType($activity, $object_id, $uid = 0)
 125         {
 126                 if (!empty($activity['as:object'])) {
 127                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 128                         if (!empty($object_type)) {
 129                                 return $object_type;
 130                         }
 131                 }
 132
 133                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 134                         // We just assume "note" since it doesn't make a difference for the further processing
 135                         return 'as:Note';
 136                 }
 137
 138                 $profile = APContact::getByURL($object_id);
 139                 if (!empty($profile['type'])) {
 140                         return 'as:' . $profile['type'];
 141                 }
 142
 143                 $data = ActivityPub::fetchContent($object_id, $uid);
 144                 if (!empty($data)) {
 145                         $object = JsonLD::compact($data);
 146                         $type = JsonLD::fetchElement($object, '@type');
 147                         if (!empty($type)) {
 148                                 return $type;
 149                         }
 150                 }
 151
 152                 return null;
 153         }
 154
 155         /**
 156          * Prepare the object array
 157          *
 158          * @param array   $activity
 159          * @param integer $uid User ID
 160          * @param         $trust_source
 161          *
 162          * @return array with object data
 163          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 164          * @throws \ImagickException
 165          */
 166         private static function prepareObjectData($activity, $uid, &$trust_source)
 167         {
 168                 $actor = JsonLD::fetchElement($activity, 'as:actor');
 169                 if (empty($actor)) {
 170                         Logger::log('Empty actor', Logger::DEBUG);
 171                         return [];
 172                 }
 173
 174                 $type = JsonLD::fetchElement($activity, '@type');
 175
 176                 // Fetch all receivers from to, cc, bto and bcc
 177                 $receivers = self::getReceivers($activity, $actor);
 178
 179                 // When it is a delivery to a personal inbox we add that user to the receivers
 180                 if (!empty($uid)) {
 181                         $additional = ['uid:' . $uid => $uid];
 182                         $receivers = array_merge($receivers, $additional);
 183                 } else {
 184                         // We possibly need some user to fetch private content,
 185                         // so we fetch the first out ot the list.
 186                         $uid = self::getFirstUserFromReceivers($receivers);
 187                 }
 188
 189                 Logger::log('Receivers: ' . $uid . ' - ' . json_encode($receivers), Logger::DEBUG);
 190
 191                 $object_id = JsonLD::fetchElement($activity, 'as:object');
 192                 if (empty($object_id)) {
 193                         Logger::log('No object found', Logger::DEBUG);
 194                         return [];
 195                 }
 196
 197                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
 198
 199                 // Fetch the content only on activities where this matters
 200                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 201                         if ($type == 'as:Announce') {
 202                                 $trust_source = false;
 203                         }
 204                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $uid);
 205                         if (empty($object_data)) {
 206                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
 207                                 return [];
 208                         }
 209                         // We had been able to retrieve the object data - so we can trust the source
 210                         $trust_source = true;
 211                 } elseif (in_array($type, ['as:Like', 'as:Dislike']) ||
 212                         (($type == 'as:Follow') && in_array($object_type, self::CONTENT_TYPES))) {
 213                         // Create a mostly empty array out of the activity data (instead of the object).
 214                         // This way we later don't have to check for the existence of ech individual array element.
 215                         $object_data = self::processObject($activity);
 216                         $object_data['name'] = $type;
 217                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor');
 218                         $object_data['object_id'] = $object_id;
 219                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 220                 } else {
 221                         $object_data = [];
 222                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 223                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object');
 224                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor');
 225                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 226                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 227
 228                         // An Undo is done on the object of an object, so we need that type as well
 229                         if ($type == 'as:Undo') {
 230                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 231                         }
 232                 }
 233
 234                 $object_data = self::addActivityFields($object_data, $activity);
 235
 236                 if (empty($object_data['object_type'])) {
 237                         $object_data['object_type'] = $object_type;
 238                 }
 239
 240                 $object_data['type'] = $type;
 241                 $object_data['actor'] = $actor;
 242                 $object_data['item_receiver'] = $receivers;
 243                 $object_data['receiver'] = array_merge(defaults($object_data, 'receiver', []), $receivers);
 244
 245                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 246
 247                 return $object_data;
 248         }
 249
 250         /**
 251          * Fetches the first user id from the receiver array
 252          *
 253          * @param array $receivers Array with receivers
 254          * @return integer user id;
 255          */
 256         public static function getFirstUserFromReceivers($receivers)
 257         {
 258                 foreach ($receivers as $receiver) {
 259                         if (!empty($receiver)) {
 260                                 return $receiver;
 261                         }
 262                 }
 263                 return 0;
 264         }
 265
 266         /**
 267          * Store the unprocessed data into the conversation table
 268          * This has to be done outside the regular function,
 269          * since we store everything - not only item posts.
 270          *
 271          * @param array  $activity Array with activity data
 272          * @param string $body     The raw message
 273          * @throws \Exception
 274          */
 275         private static function storeConversation($activity, $body)
 276         {
 277                 if (empty($body) || empty($activity['id'])) {
 278                         return;
 279                 }
 280
 281                 $conversation = [
 282                         'protocol' => Conversation::PARCEL_ACTIVITYPUB,
 283                         'item-uri' => $activity['id'],
 284                         'reply-to-uri' => defaults($activity, 'reply-to-id', ''),
 285                         'conversation-href' => defaults($activity, 'context', ''),
 286                         'conversation-uri' => defaults($activity, 'conversation', ''),
 287                         'source' => $body,
 288                         'received' => DateTimeFormat::utcNow()];
 289
 290                 DBA::insert('conversation', $conversation, true);
 291         }
 292
 293         /**
 294          * Processes the activity object
 295          *
 296          * @param array   $activity     Array with activity data
 297          * @param string  $body
 298          * @param integer $uid          User ID
 299          * @param boolean $trust_source Do we trust the source?
 300          * @throws \Exception
 301          */
 302         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false)
 303         {
 304                 $type = JsonLD::fetchElement($activity, '@type');
 305                 if (!$type) {
 306                         Logger::log('Empty type', Logger::DEBUG);
 307                         return;
 308                 }
 309
 310                 if (!JsonLD::fetchElement($activity, 'as:object')) {
 311                         Logger::log('Empty object', Logger::DEBUG);
 312                         return;
 313                 }
 314
 315                 if (!JsonLD::fetchElement($activity, 'as:actor')) {
 316                         Logger::log('Empty actor', Logger::DEBUG);
 317                         return;
 318
 319                 }
 320
 321                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
 322                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
 323                         $actor = JsonLD::fetchElement($activity, 'as:actor');
 324                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo');
 325                         $trust_source = ($actor == $attributed_to);
 326                         if (!$trust_source) {
 327                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
 328                         }
 329                 }
 330
 331                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 332                 $object_data = self::prepareObjectData($activity, $uid, $trust_source);
 333                 if (empty($object_data)) {
 334                         Logger::log('No object data found', Logger::DEBUG);
 335                         return;
 336                 }
 337
 338                 if (!$trust_source) {
 339                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
 340                         return;
 341                 }
 342
 343                 // Only store content related stuff - and no announces, since they possibly overwrite the original content
 344                 if (in_array($object_data['object_type'], self::CONTENT_TYPES) && ($type != 'as:Announce')) {
 345                         self::storeConversation($object_data, $body);
 346                 }
 347
 348                 // Internal flag for thread completion. See Processor.php
 349                 if (!empty($activity['thread-completion'])) {
 350                         $object_data['thread-completion'] = $activity['thread-completion'];
 351                 }
 352
 353                 switch ($type) {
 354                         case 'as:Create':
 355                         case 'as:Announce':
 356                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 357                                         ActivityPub\Processor::createItem($object_data);
 358                                 }
 359                                 break;
 360
 361                         case 'as:Like':
 362                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 363                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_LIKE);
 364                                 }
 365                                 break;
 366
 367                         case 'as:Dislike':
 368                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 369                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_DISLIKE);
 370                                 }
 371                                 break;
 372
 373                         case 'as:TentativeAccept':
 374                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 375                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDMAYBE);
 376                                 }
 377                                 break;
 378
 379                         case 'as:Update':
 380                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 381                                         ActivityPub\Processor::updateItem($object_data);
 382                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 383                                         ActivityPub\Processor::updatePerson($object_data);
 384                                 }
 385                                 break;
 386
 387                         case 'as:Delete':
 388                                 if ($object_data['object_type'] == 'as:Tombstone') {
 389                                         ActivityPub\Processor::deleteItem($object_data);
 390                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 391                                         ActivityPub\Processor::deletePerson($object_data);
 392                                 }
 393                                 break;
 394
 395                         case 'as:Follow':
 396                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 397                                         ActivityPub\Processor::followUser($object_data);
 398                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 399                                         $object_data['reply-to-id'] = $object_data['object_id'];
 400                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_FOLLOW);
 401                                 }
 402                                 break;
 403
 404                         case 'as:Accept':
 405                                 if ($object_data['object_type'] == 'as:Follow') {
 406                                         ActivityPub\Processor::acceptFollowUser($object_data);
 407                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 408                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTEND);
 409                                 }
 410                                 break;
 411
 412                         case 'as:Reject':
 413                                 if ($object_data['object_type'] == 'as:Follow') {
 414                                         ActivityPub\Processor::rejectFollowUser($object_data);
 415                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 416                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDNO);
 417                                 }
 418                                 break;
 419
 420                         case 'as:Undo':
 421                                 if (($object_data['object_type'] == 'as:Follow') &&
 422                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 423                                         ActivityPub\Processor::undoFollowUser($object_data);
 424                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 425                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 426                                         ActivityPub\Processor::rejectFollowUser($object_data);
 427                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 428                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 429                                         ActivityPub\Processor::undoActivity($object_data);
 430                                 }
 431                                 break;
 432
 433                         default:
 434                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 435                                 break;
 436                 }
 437         }
 438
 439         /**
 440          * Fetch the receiver list from an activity array
 441          *
 442          * @param array  $activity
 443          * @param string $actor
 444          * @param array  $tags
 445          *
 446          * @return array with receivers (user id)
 447          * @throws \Exception
 448          */
 449         private static function getReceivers($activity, $actor, $tags = [])
 450         {
 451                 $receivers = [];
 452
 453                 // When it is an answer, we inherite the receivers from the parent
 454                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo');
 455                 if (!empty($replyto)) {
 456                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 457                         while ($parent = Item::fetch($parents)) {
 458                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 459                         }
 460                 }
 461
 462                 if (!empty($actor)) {
 463                         $profile = APContact::getByURL($actor);
 464                         $followers = defaults($profile, 'followers', '');
 465
 466                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 467                 } else {
 468                         Logger::log('Empty actor', Logger::DEBUG);
 469                         $followers = '';
 470                 }
 471
 472                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 473                         $receiver_list = JsonLD::fetchElementArray($activity, $element);
 474                         if (empty($receiver_list)) {
 475                                 continue;
 476                         }
 477
 478                         foreach ($receiver_list as $receiver) {
 479                                 if ($receiver == self::PUBLIC_COLLECTION) {
 480                                         $receivers['uid:0'] = 0;
 481                                 }
 482
 483                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 484                                         // This will most likely catch all OStatus connections to Mastodon
 485                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 486                                                 , 'archive' => false, 'pending' => false];
 487                                         $contacts = DBA::select('contact', ['uid'], $condition);
 488                                         while ($contact = DBA::fetch($contacts)) {
 489                                                 if ($contact['uid'] != 0) {
 490                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 491                                                 }
 492                                         }
 493                                         DBA::close($contacts);
 494                                 }
 495
 496                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 497                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 498                                         continue;
 499                                 }
 500
 501                                 // Fetching all directly addressed receivers
 502                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 503                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 504                                 if (!DBA::isResult($contact)) {
 505                                         continue;
 506                                 }
 507
 508                                 // Check if the potential receiver is following the actor
 509                                 // Exception: The receiver is targetted via "to" or this is a comment
 510                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 511                                         $networks = [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::DIASPORA, Protocol::OSTATUS];
 512                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 513                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 514
 515                                         // Forum posts are only accepted from forum contacts
 516                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 517                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 518                                         }
 519
 520                                         if (!DBA::exists('contact', $condition)) {
 521                                                 continue;
 522                                         }
 523                                 }
 524
 525                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 526                         }
 527                 }
 528
 529                 self::switchContacts($receivers, $actor);
 530
 531                 return $receivers;
 532         }
 533
 534         /**
 535          * Fetch the receiver list of a given actor
 536          *
 537          * @param string $actor
 538          * @param array  $tags
 539          *
 540          * @return array with receivers (user id)
 541          * @throws \Exception
 542          */
 543         public static function getReceiverForActor($actor, $tags)
 544         {
 545                 $receivers = [];
 546                 $networks = [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::DIASPORA, Protocol::OSTATUS];
 547                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 548                         'network' => $networks, 'archive' => false, 'pending' => false];
 549                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 550                 while ($contact = DBA::fetch($contacts)) {
 551                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 552                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 553                         }
 554                 }
 555                 DBA::close($contacts);
 556                 return $receivers;
 557         }
 558
 559         /**
 560          * Tests if the contact is a valid receiver for this actor
 561          *
 562          * @param array  $contact
 563          * @param string $actor
 564          * @param array  $tags
 565          *
 566          * @return bool with receivers (user id)
 567          * @throws \Exception
 568          */
 569         private static function isValidReceiverForActor($contact, $actor, $tags)
 570         {
 571                 // Public contacts are no valid receiver
 572                 if ($contact['uid'] == 0) {
 573                         return false;
 574                 }
 575
 576                 // Are we following the contact? Then this is a valid receiver
 577                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 578                         return true;
 579                 }
 580
 581                 // When the possible receiver isn't a community, then it is no valid receiver
 582                 $owner = User::getOwnerDataById($contact['uid']);
 583                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 584                         return false;
 585                 }
 586
 587                 // Is the community account tagged?
 588                 foreach ($tags as $tag) {
 589                         if ($tag['type'] != 'Mention') {
 590                                 continue;
 591                         }
 592
 593                         if ($tag['href'] == $owner['url']) {
 594                                 return true;
 595                         }
 596                 }
 597
 598                 return false;
 599         }
 600
 601         /**
 602          * Switches existing contacts to ActivityPub
 603          *
 604          * @param integer $cid Contact ID
 605          * @param integer $uid User ID
 606          * @param string  $url Profile URL
 607          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 608          * @throws \ImagickException
 609          */
 610         public static function switchContact($cid, $uid, $url)
 611         {
 612                 $profile = ActivityPub::probeProfile($url);
 613                 if (empty($profile)) {
 614                         return;
 615                 }
 616
 617                 Logger::log('Switch contact ' . $cid . ' (' . $profile['url'] . ') for user ' . $uid . ' to ActivityPub');
 618
 619                 $photo = defaults($profile, 'photo', null);
 620                 unset($profile['photo']);
 621                 unset($profile['baseurl']);
 622                 unset($profile['guid']);
 623
 624                 $profile['nurl'] = Strings::normaliseLink($profile['url']);
 625                 DBA::update('contact', $profile, ['id' => $cid]);
 626
 627                 Contact::updateAvatar($photo, $uid, $cid);
 628
 629                 // Send a new follow request to be sure that the connection still exists
 630                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND]])) {
 631                         ActivityPub\Transmitter::sendActivity('Follow', $profile['url'], $uid);
 632                         Logger::log('Send a new follow request to ' . $profile['url'] . ' for user ' . $uid, Logger::DEBUG);
 633                 }
 634         }
 635
 636         /**
 637          *
 638          *
 639          * @param $receivers
 640          * @param $actor
 641          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 642          * @throws \ImagickException
 643          */
 644         private static function switchContacts($receivers, $actor)
 645         {
 646                 if (empty($actor)) {
 647                         return;
 648                 }
 649
 650                 foreach ($receivers as $receiver) {
 651                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 652                         if (DBA::isResult($contact)) {
 653                                 self::switchContact($contact['id'], $receiver, $actor);
 654                         }
 655
 656                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 657                         if (DBA::isResult($contact)) {
 658                                 self::switchContact($contact['id'], $receiver, $actor);
 659                         }
 660                 }
 661         }
 662
 663         /**
 664          *
 665          *
 666          * @param       $object_data
 667          * @param array $activity
 668          *
 669          * @return mixed
 670          */
 671         private static function addActivityFields($object_data, $activity)
 672         {
 673                 if (!empty($activity['published']) && empty($object_data['published'])) {
 674                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 675                 }
 676
 677                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 678                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid');
 679                 }
 680
 681                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 682
 683                 return $object_data;
 684         }
 685
 686         /**
 687          * Fetches the object data from external ressources if needed
 688          *
 689          * @param string  $object_id    Object ID of the the provided object
 690          * @param array   $object       The provided object array
 691          * @param boolean $trust_source Do we trust the provided object?
 692          * @param integer $uid          User ID for the signature that we use to fetch data
 693          *
 694          * @return array with trusted and valid object data
 695          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 696          * @throws \ImagickException
 697          */
 698         private static function fetchObject($object_id, $object = [], $trust_source = false, $uid = 0)
 699         {
 700                 // By fetching the type we check if the object is complete.
 701                 $type = JsonLD::fetchElement($object, '@type');
 702
 703                 if (!$trust_source || empty($type)) {
 704                         $data = ActivityPub::fetchContent($object_id, $uid);
 705                         if (!empty($data)) {
 706                                 $object = JsonLD::compact($data);
 707                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 708                         } else {
 709                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 710
 711                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 712                                 if (!DBA::isResult($item)) {
 713                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 714                                         return false;
 715                                 }
 716                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 717                                 $data = ActivityPub\Transmitter::createNote($item);
 718                                 $object = JsonLD::compact($data);
 719                         }
 720                 } else {
 721                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 722                 }
 723
 724                 $type = JsonLD::fetchElement($object, '@type');
 725
 726                 if (empty($type)) {
 727                         Logger::log('Empty type', Logger::DEBUG);
 728                         return false;
 729                 }
 730
 731                 if (in_array($type, self::CONTENT_TYPES)) {
 732                         return self::processObject($object);
 733                 }
 734
 735                 if ($type == 'as:Announce') {
 736                         $object_id = JsonLD::fetchElement($object, 'object');
 737                         if (empty($object_id)) {
 738                                 return false;
 739                         }
 740                         return self::fetchObject($object_id, [], false, $uid);
 741                 }
 742
 743                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 744         }
 745
 746         /**
 747          * Convert tags from JSON-LD format into a simplified format
 748          *
 749          * @param array $tags Tags in JSON-LD format
 750          *
 751          * @return array with tags in a simplified format
 752          */
 753         private static function processTags($tags)
 754         {
 755                 $taglist = [];
 756
 757                 if (empty($tags)) {
 758                         return [];
 759                 }
 760
 761                 foreach ($tags as $tag) {
 762                         if (empty($tag)) {
 763                                 continue;
 764                         }
 765
 766                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 767                                 'href' => JsonLD::fetchElement($tag, 'as:href'),
 768                                 'name' => JsonLD::fetchElement($tag, 'as:name')];
 769
 770                         if (empty($element['type'])) {
 771                                 continue;
 772                         }
 773
 774                         $taglist[] = $element;
 775                 }
 776                 return $taglist;
 777         }
 778
 779         /**
 780          * Convert emojis from JSON-LD format into a simplified format
 781          *
 782          * @param $emojis
 783          * @return array with emojis in a simplified format
 784          */
 785         private static function processEmojis($emojis)
 786         {
 787                 $emojilist = [];
 788
 789                 if (empty($emojis)) {
 790                         return [];
 791                 }
 792
 793                 foreach ($emojis as $emoji) {
 794                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
 795                                 continue;
 796                         }
 797
 798                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url');
 799                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name'),
 800                                 'href' => $url];
 801
 802                         $emojilist[] = $element;
 803                 }
 804                 return $emojilist;
 805         }
 806
 807         /**
 808          * Convert attachments from JSON-LD format into a simplified format
 809          *
 810          * @param array $attachments Attachments in JSON-LD format
 811          *
 812          * @return array with attachmants in a simplified format
 813          */
 814         private static function processAttachments($attachments)
 815         {
 816                 $attachlist = [];
 817
 818                 if (empty($attachments)) {
 819                         return [];
 820                 }
 821
 822                 foreach ($attachments as $attachment) {
 823                         if (empty($attachment)) {
 824                                 continue;
 825                         }
 826
 827                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 828                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType'),
 829                                 'name' => JsonLD::fetchElement($attachment, 'as:name'),
 830                                 'url' => JsonLD::fetchElement($attachment, 'as:url')];
 831                 }
 832                 return $attachlist;
 833         }
 834
 835         /**
 836          * Fetches data from the object part of an activity
 837          *
 838          * @param array $object
 839          *
 840          * @return array
 841          * @throws \Exception
 842          */
 843         private static function processObject($object)
 844         {
 845                 if (!JsonLD::fetchElement($object, '@id')) {
 846                         return false;
 847                 }
 848
 849                 $object_data = [];
 850                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 851                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 852                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo');
 853
 854                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
 855                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
 856                         $object_data['reply-to-id'] = $object_data['id'];
 857                 }
 858
 859                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 860                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 861
 862                 if (empty($object_data['updated'])) {
 863                         $object_data['updated'] = $object_data['published'];
 864                 }
 865
 866                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 867                         $object_data['published'] = $object_data['updated'];
 868                 }
 869
 870                 $actor = JsonLD::fetchElement($object, 'as:attributedTo');
 871                 if (empty($actor)) {
 872                         $actor = JsonLD::fetchElement($object, 'as:actor');
 873                 }
 874
 875                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid');
 876                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment');
 877                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like');
 878                 $object_data['actor'] = $object_data['author'] = $actor;
 879                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context');
 880                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation');
 881                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 882                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name');
 883                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary');
 884                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content');
 885                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 886                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
 887                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
 888                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
 889                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
 890                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
 891                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
 892                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
 893                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
 894                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
 895                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji'));
 896                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
 897                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url');
 898
 899                 // Special treatment for Hubzilla links
 900                 if (is_array($object_data['alternate-url'])) {
 901                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href');
 902
 903                         if (!is_string($object_data['alternate-url'])) {
 904                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href');
 905                         }
 906                 }
 907
 908                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags']);
 909
 910                 // Common object data:
 911
 912                 // Unhandled
 913                 // @context, type, actor, signature, mediaType, duration, replies, icon
 914
 915                 // Also missing: (Defined in the standard, but currently unused)
 916                 // audience, preview, endTime, startTime, image
 917
 918                 // Data in Notes:
 919
 920                 // Unhandled
 921                 // contentMap, announcement_count, announcements, context_id, likes, like_count
 922                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
 923
 924                 // Data in video:
 925
 926                 // To-Do?
 927                 // category, licence, language, commentsEnabled
 928
 929                 // Unhandled
 930                 // views, waitTranscoding, state, support, subtitleLanguage
 931                 // likes, dislikes, shares, comments
 932
 933                 return $object_data;
 934         }
 935 }