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