src/Protocol/ActivityPub/Receiver.php

   1 <?php
   2 /**
   3  * @file src/Protocol/ActivityPub/Receiver.php
   4  */
   5 namespace Friendica\Protocol\ActivityPub;
   6
   7 use Friendica\Database\DBA;
   8 use Friendica\Util\HTTPSignature;
   9 use Friendica\Core\Logger;
  10 use Friendica\Core\Protocol;
  11 use Friendica\Model\Contact;
  12 use Friendica\Model\APContact;
  13 use Friendica\Model\Item;
  14 use Friendica\Model\User;
  15 use Friendica\Util\JsonLD;
  16 use Friendica\Util\LDSignature;
  17 use Friendica\Protocol\ActivityPub;
  18 use Friendica\Model\Conversation;
  19 use Friendica\Util\DateTimeFormat;
  20
  21 /**
  22  * @brief ActivityPub Receiver Protocol class
  23  *
  24  * To-Do:
  25  * - Undo Announce
  26  *
  27  * Check what this is meant to do:
  28  * - Add
  29  * - Block
  30  * - Flag
  31  * - Remove
  32  * - Undo Block
  33  */
  34 class Receiver
  35 {
  36         const PUBLIC_COLLECTION = 'as:Public';
  37         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  38         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event'];
  39         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  40
  41         /**
  42          * Checks if the web request is done for the AP protocol
  43          *
  44          * @return is it AP?
  45          */
  46         public static function isRequest()
  47         {
  48                 return stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json') ||
  49                         stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/ld+json');
  50         }
  51
  52         /**
  53          * Checks incoming message from the inbox
  54          *
  55          * @param $body
  56          * @param $header
  57          * @param integer $uid User ID
  58          */
  59         public static function processInbox($body, $header, $uid)
  60         {
  61                 $http_signer = HTTPSignature::getSigner($body, $header);
  62                 if (empty($http_signer)) {
  63                         Logger::log('Invalid HTTP signature, message will be discarded.', Logger::DEBUG);
  64                         return;
  65                 } else {
  66                         Logger::log('HTTP signature is signed by ' . $http_signer, Logger::DEBUG);
  67                 }
  68
  69                 $activity = json_decode($body, true);
  70
  71                 if (empty($activity)) {
  72                         Logger::log('Invalid body.', Logger::DEBUG);
  73                         return;
  74                 }
  75
  76                 $ldactivity = JsonLD::compact($activity);
  77
  78                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor');
  79
  80                 Logger::log('Message for user ' . $uid . ' is from actor ' . $actor, Logger::DEBUG);
  81
  82                 if (LDSignature::isSigned($activity)) {
  83                         $ld_signer = LDSignature::getSigner($activity);
  84                         if (empty($ld_signer)) {
  85                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
  86                         }
  87                         if (!empty($ld_signer && ($actor == $http_signer))) {
  88                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
  89                                 $trust_source = true;
  90                         } elseif (!empty($ld_signer)) {
  91                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
  92                                 $trust_source = true;
  93                         } elseif ($actor == $http_signer) {
  94                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
  95                                 $trust_source = true;
  96                         } else {
  97                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
  98                                 $trust_source = false;
  99                         }
 100                 } elseif ($actor == $http_signer) {
 101                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
 102                         $trust_source = true;
 103                 } else {
 104                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
 105                         $trust_source = false;
 106                 }
 107
 108                 self::processActivity($ldactivity, $body, $uid, $trust_source);
 109         }
 110
 111         /**
 112          * Fetches the object type for a given object id
 113          *
 114          * @param array   $activity
 115          * @param string  $object_id Object ID of the the provided object
 116          * @param integer $uid User ID
 117          *
 118          * @return string with object type
 119          */
 120         private static function fetchObjectType($activity, $object_id, $uid = 0)
 121         {
 122                 if (!empty($activity['as:object'])) {
 123                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 124                         if (!empty($object_type)) {
 125                                 return $object_type;
 126                         }
 127                 }
 128
 129                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 130                         // We just assume "note" since it doesn't make a difference for the further processing
 131                         return 'as:Note';
 132                 }
 133
 134                 $profile = APContact::getByURL($object_id);
 135                 if (!empty($profile['type'])) {
 136                         return 'as:' . $profile['type'];
 137                 }
 138
 139                 $data = ActivityPub::fetchContent($object_id, $uid);
 140                 if (!empty($data)) {
 141                         $object = JsonLD::compact($data);
 142                         $type = JsonLD::fetchElement($object, '@type');
 143                         if (!empty($type)) {
 144                                 return $type;
 145                         }
 146                 }
 147
 148                 return null;
 149         }
 150
 151         /**
 152          * Prepare the object array
 153          *
 154          * @param array $activity
 155          * @param integer $uid User ID
 156          * @param $trust_source
 157          *
 158          * @return array with object data
 159          */
 160         private static function prepareObjectData($activity, $uid, &$trust_source)
 161         {
 162                 $actor = JsonLD::fetchElement($activity, 'as:actor');
 163                 if (empty($actor)) {
 164                         Logger::log('Empty actor', Logger::DEBUG);
 165                         return [];
 166                 }
 167
 168                 $type = JsonLD::fetchElement($activity, '@type');
 169
 170                 // Fetch all receivers from to, cc, bto and bcc
 171                 $receivers = self::getReceivers($activity, $actor);
 172
 173                 // When it is a delivery to a personal inbox we add that user to the receivers
 174                 if (!empty($uid)) {
 175                         $additional = ['uid:' . $uid => $uid];
 176                         $receivers = array_merge($receivers, $additional);
 177                 } else {
 178                         // We possibly need some user to fetch private content,
 179                         // so we fetch the first out ot the list.
 180                         $uid = self::getFirstUserFromReceivers($receivers);
 181                 }
 182
 183                 Logger::log('Receivers: ' . $uid . ' - ' . json_encode($receivers), Logger::DEBUG);
 184
 185                 $object_id = JsonLD::fetchElement($activity, 'as:object');
 186                 if (empty($object_id)) {
 187                         Logger::log('No object found', Logger::DEBUG);
 188                         return [];
 189                 }
 190
 191                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
 192
 193                 // Fetch the content only on activities where this matters
 194                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 195                         if ($type == 'as:Announce') {
 196                                 $trust_source = false;
 197                         }
 198                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $uid);
 199                         if (empty($object_data)) {
 200                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
 201                                 return [];
 202                         }
 203                         // We had been able to retrieve the object data - so we can trust the source
 204                         $trust_source = true;
 205                 } elseif (in_array($type, ['as:Like', 'as:Dislike'])) {
 206                         // Create a mostly empty array out of the activity data (instead of the object).
 207                         // This way we later don't have to check for the existence of ech individual array element.
 208                         $object_data = self::processObject($activity);
 209                         $object_data['name'] = $type;
 210                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor');
 211                         $object_data['object_id'] = $object_id;
 212                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 213                 } else {
 214                         $object_data = [];
 215                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 216                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object');
 217                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor');
 218                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 219                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 220
 221                         // An Undo is done on the object of an object, so we need that type as well
 222                         if ($type == 'as:Undo') {
 223                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 224                         }
 225                 }
 226
 227                 $object_data = self::addActivityFields($object_data, $activity);
 228
 229                 if (empty($object_data['object_type'])) {
 230                         $object_data['object_type'] = $object_type;
 231                 }
 232
 233                 $object_data['type'] = $type;
 234                 $object_data['actor'] = $actor;
 235                 $object_data['receiver'] = array_merge(defaults($object_data, 'receiver', []), $receivers);
 236
 237                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 238
 239                 return $object_data;
 240         }
 241
 242         /**
 243          * Fetches the first uider id from the receiver array
 244          *
 245          * @param array $receivers Array with receivers
 246          * @return integer user id;
 247          */
 248         public static function getFirstUserFromReceivers($receivers)
 249         {
 250                 foreach ($receivers as $receiver) {
 251                         if (!empty($receiver)) {
 252                                 return $receiver;
 253                         }
 254                 }
 255                 return 0;
 256         }
 257
 258         /**
 259          * Store the unprocessed data into the conversation table
 260          * This has to be done outside the regular function,
 261          * since we store everything - not only item posts.
 262          *
 263          * @param array  $activity Array with activity data
 264          * @param string $body     The raw message
 265          */
 266         private static function storeConversation($activity, $body)
 267         {
 268                 if (empty($body) || empty($activity['id'])) {
 269                         return;
 270                 }
 271
 272                 $conversation = [
 273                         'protocol' => Conversation::PARCEL_ACTIVITYPUB,
 274                         'item-uri' => $activity['id'],
 275                         'reply-to-uri' => defaults($activity, 'reply-to-id', ''),
 276                         'conversation-href' => defaults($activity, 'context', ''),
 277                         'conversation-uri' => defaults($activity, 'conversation', ''),
 278                         'source' => $body,
 279                         'received' => DateTimeFormat::utcNow()];
 280
 281                 DBA::insert('conversation', $conversation, true);
 282         }
 283
 284         /**
 285          * Processes the activity object
 286          *
 287          * @param array   $activity     Array with activity data
 288          * @param string  $body
 289          * @param integer $uid          User ID
 290          * @param boolean $trust_source Do we trust the source?
 291          */
 292         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false)
 293         {
 294                 $type = JsonLD::fetchElement($activity, '@type');
 295                 if (!$type) {
 296                         Logger::log('Empty type', Logger::DEBUG);
 297                         return;
 298                 }
 299
 300                 if (!JsonLD::fetchElement($activity, 'as:object')) {
 301                         Logger::log('Empty object', Logger::DEBUG);
 302                         return;
 303                 }
 304
 305                 if (!JsonLD::fetchElement($activity, 'as:actor')) {
 306                         Logger::log('Empty actor', Logger::DEBUG);
 307                         return;
 308
 309                 }
 310
 311                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 312                 $object_data = self::prepareObjectData($activity, $uid, $trust_source);
 313                 if (empty($object_data)) {
 314                         Logger::log('No object data found', Logger::DEBUG);
 315                         return;
 316                 }
 317
 318                 if (!$trust_source) {
 319                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
 320                         return;
 321                 }
 322
 323                 self::storeConversation($object_data, $body);
 324
 325                 // Internal flag for thread completion. See Processor.php
 326                 if (!empty($activity['thread-completion'])) {
 327                         $object_data['thread-completion'] = $activity['thread-completion'];
 328                 }
 329
 330                 switch ($type) {
 331                         case 'as:Create':
 332                         case 'as:Announce':
 333                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 334                                         ActivityPub\Processor::createItem($object_data);
 335                                 }
 336                                 break;
 337
 338                         case 'as:Like':
 339                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 340                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_LIKE);
 341                                 }
 342                                 break;
 343
 344                         case 'as:Dislike':
 345                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 346                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_DISLIKE);
 347                                 }
 348                                 break;
 349
 350                         case 'as:TentativeAccept':
 351                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 352                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDMAYBE);
 353                                 }
 354                                 break;
 355
 356                         case 'as:Update':
 357                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 358                                         ActivityPub\Processor::updateItem($object_data);
 359                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 360                                         ActivityPub\Processor::updatePerson($object_data, $body);
 361                                 }
 362                                 break;
 363
 364                         case 'as:Delete':
 365                                 if ($object_data['object_type'] == 'as:Tombstone') {
 366                                         ActivityPub\Processor::deleteItem($object_data, $body);
 367                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 368                                         ActivityPub\Processor::deletePerson($object_data, $body);
 369                                 }
 370                                 break;
 371
 372                         case 'as:Follow':
 373                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 374                                         ActivityPub\Processor::followUser($object_data);
 375                                 }
 376                                 break;
 377
 378                         case 'as:Accept':
 379                                 if ($object_data['object_type'] == 'as:Follow') {
 380                                         ActivityPub\Processor::acceptFollowUser($object_data);
 381                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 382                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTEND);
 383                                 }
 384                                 break;
 385
 386                         case 'as:Reject':
 387                                 if ($object_data['object_type'] == 'as:Follow') {
 388                                         ActivityPub\Processor::rejectFollowUser($object_data);
 389                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 390                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDNO);
 391                                 }
 392                                 break;
 393
 394                         case 'as:Undo':
 395                                 if (($object_data['object_type'] == 'as:Follow') &&
 396                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 397                                         ActivityPub\Processor::undoFollowUser($object_data);
 398                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 399                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 400                                         ActivityPub\Processor::rejectFollowUser($object_data);
 401                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 402                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 403                                         ActivityPub\Processor::undoActivity($object_data);
 404                                 }
 405                                 break;
 406
 407                         default:
 408                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 409                                 break;
 410                 }
 411         }
 412
 413         /**
 414          * Fetch the receiver list from an activity array
 415          *
 416          * @param array $activity
 417          * @param string $actor
 418          * @param array $tags
 419          *
 420          * @return array with receivers (user id)
 421          */
 422         private static function getReceivers($activity, $actor, $tags = [])
 423         {
 424                 $receivers = [];
 425
 426                 // When it is an answer, we inherite the receivers from the parent
 427                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo');
 428                 if (!empty($replyto)) {
 429                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 430                         while ($parent = Item::fetch($parents)) {
 431                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 432                         }
 433                 }
 434
 435                 if (!empty($actor)) {
 436                         $profile = APContact::getByURL($actor);
 437                         $followers = defaults($profile, 'followers', '');
 438
 439                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 440                 } else {
 441                         Logger::log('Empty actor', Logger::DEBUG);
 442                         $followers = '';
 443                 }
 444
 445                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 446                         $receiver_list = JsonLD::fetchElementArray($activity, $element);
 447                         if (empty($receiver_list)) {
 448                                 continue;
 449                         }
 450
 451                         foreach ($receiver_list as $receiver) {
 452                                 if ($receiver == self::PUBLIC_COLLECTION) {
 453                                         $receivers['uid:0'] = 0;
 454                                 }
 455
 456                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 457                                         // This will most likely catch all OStatus connections to Mastodon
 458                                         $condition = ['alias' => [$actor, normalise_link($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 459                                                 , 'archive' => false, 'pending' => false];
 460                                         $contacts = DBA::select('contact', ['uid'], $condition);
 461                                         while ($contact = DBA::fetch($contacts)) {
 462                                                 if ($contact['uid'] != 0) {
 463                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 464                                                 }
 465                                         }
 466                                         DBA::close($contacts);
 467                                 }
 468
 469                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 470                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 471                                         continue;
 472                                 }
 473
 474                                 // Fetching all directly addressed receivers
 475                                 $condition = ['self' => true, 'nurl' => normalise_link($receiver)];
 476                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 477                                 if (!DBA::isResult($contact)) {
 478                                         continue;
 479                                 }
 480
 481                                 // Check if the potential receiver is following the actor
 482                                 // Exception: The receiver is targetted via "to" or this is a comment
 483                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::ACCOUNT_TYPE_COMMUNITY)) {
 484                                         $networks = [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::DIASPORA, Protocol::OSTATUS];
 485                                         $condition = ['nurl' => normalise_link($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 486                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 487
 488                                         // Forum posts are only accepted from forum contacts
 489                                         if ($contact['contact-type'] == Contact::ACCOUNT_TYPE_COMMUNITY) {
 490                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 491                                         }
 492
 493                                         if (!DBA::exists('contact', $condition)) {
 494                                                 continue;
 495                                         }
 496                                 }
 497
 498                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 499                         }
 500                 }
 501
 502                 self::switchContacts($receivers, $actor);
 503
 504                 return $receivers;
 505         }
 506
 507         /**
 508          * Fetch the receiver list of a given actor
 509          *
 510          * @param string $actor
 511          * @param array $tags
 512          *
 513          * @return array with receivers (user id)
 514          */
 515         public static function getReceiverForActor($actor, $tags)
 516         {
 517                 $receivers = [];
 518                 $networks = [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::DIASPORA, Protocol::OSTATUS];
 519                 $condition = ['nurl' => normalise_link($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 520                         'network' => $networks, 'archive' => false, 'pending' => false];
 521                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 522                 while ($contact = DBA::fetch($contacts)) {
 523                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 524                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 525                         }
 526                 }
 527                 DBA::close($contacts);
 528                 return $receivers;
 529         }
 530
 531         /**
 532          * Tests if the contact is a valid receiver for this actor
 533          *
 534          * @param array $contact
 535          * @param string $actor
 536          * @param array $tags
 537          *
 538          * @return array with receivers (user id)
 539          */
 540         private static function isValidReceiverForActor($contact, $actor, $tags)
 541         {
 542                 // Public contacts are no valid receiver
 543                 if ($contact['uid'] == 0) {
 544                         return false;
 545                 }
 546
 547                 // Are we following the contact? Then this is a valid receiver
 548                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 549                         return true;
 550                 }
 551
 552                 // When the possible receiver isn't a community, then it is no valid receiver
 553                 $owner = User::getOwnerDataById($contact['uid']);
 554                 if (empty($owner) || ($owner['contact-type'] != Contact::ACCOUNT_TYPE_COMMUNITY)) {
 555                         return false;
 556                 }
 557
 558                 // Is the community account tagged?
 559                 foreach ($tags as $tag) {
 560                         if ($tag['type'] != 'Mention') {
 561                                 continue;
 562                         }
 563
 564                         if ($tag['href'] == $owner['url']) {
 565                                 return true;
 566                         }
 567                 }
 568
 569                 return false;
 570         }
 571
 572         /**
 573          * Switches existing contacts to ActivityPub
 574          *
 575          * @param integer $cid Contact ID
 576          * @param integer $uid User ID
 577          * @param string $url Profile URL
 578          */
 579         public static function switchContact($cid, $uid, $url)
 580         {
 581                 $profile = ActivityPub::probeProfile($url);
 582                 if (empty($profile)) {
 583                         return;
 584                 }
 585
 586                 Logger::log('Switch contact ' . $cid . ' (' . $profile['url'] . ') for user ' . $uid . ' to ActivityPub');
 587
 588                 $photo = defaults($profile, 'photo', null);
 589                 unset($profile['photo']);
 590                 unset($profile['baseurl']);
 591
 592                 $profile['nurl'] = normalise_link($profile['url']);
 593                 DBA::update('contact', $profile, ['id' => $cid]);
 594
 595                 Contact::updateAvatar($photo, $uid, $cid);
 596
 597                 // Send a new follow request to be sure that the connection still exists
 598                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND]])) {
 599                         ActivityPub\Transmitter::sendActivity('Follow', $profile['url'], $uid);
 600                         Logger::log('Send a new follow request to ' . $profile['url'] . ' for user ' . $uid, Logger::DEBUG);
 601                 }
 602         }
 603
 604         /**
 605          *
 606          *
 607          * @param $receivers
 608          * @param $actor
 609          */
 610         private static function switchContacts($receivers, $actor)
 611         {
 612                 if (empty($actor)) {
 613                         return;
 614                 }
 615
 616                 foreach ($receivers as $receiver) {
 617                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => normalise_link($actor)]);
 618                         if (DBA::isResult($contact)) {
 619                                 self::switchContact($contact['id'], $receiver, $actor);
 620                         }
 621
 622                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [normalise_link($actor), $actor]]);
 623                         if (DBA::isResult($contact)) {
 624                                 self::switchContact($contact['id'], $receiver, $actor);
 625                         }
 626                 }
 627         }
 628
 629         /**
 630          *
 631          *
 632          * @param $object_data
 633          * @param array $activity
 634          *
 635          * @return
 636          */
 637         private static function addActivityFields($object_data, $activity)
 638         {
 639                 if (!empty($activity['published']) && empty($object_data['published'])) {
 640                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 641                 }
 642
 643                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 644                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid');
 645                 }
 646
 647                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 648
 649                 return $object_data;
 650         }
 651
 652         /**
 653          * Fetches the object data from external ressources if needed
 654          *
 655          * @param string  $object_id    Object ID of the the provided object
 656          * @param array   $object       The provided object array
 657          * @param boolean $trust_source Do we trust the provided object?
 658          * @param integer $uid          User ID for the signature that we use to fetch data
 659          *
 660          * @return array with trusted and valid object data
 661          */
 662         private static function fetchObject($object_id, $object = [], $trust_source = false, $uid = 0)
 663         {
 664                 // By fetching the type we check if the object is complete.
 665                 $type = JsonLD::fetchElement($object, '@type');
 666
 667                 if (!$trust_source || empty($type)) {
 668                         $data = ActivityPub::fetchContent($object_id, $uid);
 669                         if (!empty($data)) {
 670                                 $object = JsonLD::compact($data);
 671                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 672                         } else {
 673                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 674
 675                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 676                                 if (!DBA::isResult($item)) {
 677                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 678                                         return false;
 679                                 }
 680                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 681                                 $data = ActivityPub\Transmitter::createNote($item);
 682                                 $object = JsonLD::compact($data);
 683                         }
 684                 } else {
 685                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 686                 }
 687
 688                 $type = JsonLD::fetchElement($object, '@type');
 689
 690                 if (empty($type)) {
 691                         Logger::log('Empty type', Logger::DEBUG);
 692                         return false;
 693                 }
 694
 695                 if (in_array($type, self::CONTENT_TYPES)) {
 696                         return self::processObject($object);
 697                 }
 698
 699                 if ($type == 'as:Announce') {
 700                         $object_id = JsonLD::fetchElement($object, 'object');
 701                         if (empty($object_id)) {
 702                                 return false;
 703                         }
 704                         return self::fetchObject($object_id, [], false, $uid);
 705                 }
 706
 707                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 708         }
 709
 710         /**
 711          * Convert tags from JSON-LD format into a simplified format
 712          *
 713          * @param array $tags Tags in JSON-LD format
 714          *
 715          * @return array with tags in a simplified format
 716          */
 717         private static function processTags($tags)
 718         {
 719                 $taglist = [];
 720
 721                 if (empty($tags)) {
 722                         return [];
 723                 }
 724
 725                 foreach ($tags as $tag) {
 726                         if (empty($tag)) {
 727                                 continue;
 728                         }
 729
 730                         $taglist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 731                                 'href' => JsonLD::fetchElement($tag, 'as:href'),
 732                                 'name' => JsonLD::fetchElement($tag, 'as:name')];
 733                 }
 734                 return $taglist;
 735         }
 736
 737         /**
 738          * Convert attachments from JSON-LD format into a simplified format
 739          *
 740          * @param array $attachments Attachments in JSON-LD format
 741          *
 742          * @return array with attachmants in a simplified format
 743          */
 744         private static function processAttachments($attachments)
 745         {
 746                 $attachlist = [];
 747
 748                 if (empty($attachments)) {
 749                         return [];
 750                 }
 751
 752                 foreach ($attachments as $attachment) {
 753                         if (empty($attachment)) {
 754                                 continue;
 755                         }
 756
 757                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 758                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType'),
 759                                 'name' => JsonLD::fetchElement($attachment, 'as:name'),
 760                                 'url' => JsonLD::fetchElement($attachment, 'as:url')];
 761                 }
 762                 return $attachlist;
 763         }
 764
 765         /**
 766          * Fetches data from the object part of an activity
 767          *
 768          * @param array $object
 769          *
 770          * @return array
 771          */
 772         private static function processObject($object)
 773         {
 774                 if (!JsonLD::fetchElement($object, '@id')) {
 775                         return false;
 776                 }
 777
 778                 $object_data = [];
 779                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 780                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 781
 782                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo');
 783
 784                 if (empty($object_data['reply-to-id'])) {
 785                         $object_data['reply-to-id'] = $object_data['id'];
 786                 }
 787
 788                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 789                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 790
 791                 if (empty($object_data['updated'])) {
 792                         $object_data['updated'] = $object_data['published'];
 793                 }
 794
 795                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 796                         $object_data['published'] = $object_data['updated'];
 797                 }
 798
 799                 $actor = JsonLD::fetchElement($object, 'as:attributedTo');
 800                 if (empty($actor)) {
 801                         $actor = JsonLD::fetchElement($object, 'as:actor');
 802                 }
 803
 804                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid');
 805                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment');
 806                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like');
 807                 $object_data['actor'] = $object_data['author'] = $actor;
 808                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context');
 809                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation');
 810                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 811                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name');
 812                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary');
 813                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content');
 814                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 815                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
 816                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
 817                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
 818                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
 819                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
 820                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
 821                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
 822                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
 823                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
 824                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
 825                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url');
 826
 827                 // Special treatment for Hubzilla links
 828                 if (is_array($object_data['alternate-url'])) {
 829                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href');
 830
 831                         if (!is_string($object_data['alternate-url'])) {
 832                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href');
 833                         }
 834                 }
 835
 836                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags']);
 837
 838                 // Common object data:
 839
 840                 // Unhandled
 841                 // @context, type, actor, signature, mediaType, duration, replies, icon
 842
 843                 // Also missing: (Defined in the standard, but currently unused)
 844                 // audience, preview, endTime, startTime, image
 845
 846                 // Data in Notes:
 847
 848                 // Unhandled
 849                 // contentMap, announcement_count, announcements, context_id, likes, like_count
 850                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
 851
 852                 // Data in video:
 853
 854                 // To-Do?
 855                 // category, licence, language, commentsEnabled
 856
 857                 // Unhandled
 858                 // views, waitTranscoding, state, support, subtitleLanguage
 859                 // likes, dislikes, shares, comments
 860
 861                 return $object_data;
 862         }
 863 }