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', '@id');
  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', '@id');
 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', '@id');
 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                         $object_data['object_id'] = $object_id;
 210                         $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 211
 212                         // We had been able to retrieve the object data - so we can trust the source
 213                         $trust_source = true;
 214                 } elseif (in_array($type, ['as:Like', 'as:Dislike']) ||
 215                         (($type == 'as:Follow') && in_array($object_type, self::CONTENT_TYPES))) {
 216                         // Create a mostly empty array out of the activity data (instead of the object).
 217                         // This way we later don't have to check for the existence of ech individual array element.
 218                         $object_data = self::processObject($activity);
 219                         $object_data['name'] = $type;
 220                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 221                         $object_data['object_id'] = $object_id;
 222                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 223                 } else {
 224                         $object_data = [];
 225                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 226                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 227                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 228                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 229                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 230
 231                         // An Undo is done on the object of an object, so we need that type as well
 232                         if ($type == 'as:Undo') {
 233                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 234                         }
 235                 }
 236
 237                 $object_data = self::addActivityFields($object_data, $activity);
 238
 239                 if (empty($object_data['object_type'])) {
 240                         $object_data['object_type'] = $object_type;
 241                 }
 242
 243                 $object_data['type'] = $type;
 244                 $object_data['actor'] = $actor;
 245                 $object_data['item_receiver'] = $receivers;
 246                 $object_data['receiver'] = array_merge(defaults($object_data, 'receiver', []), $receivers);
 247
 248                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 249
 250                 return $object_data;
 251         }
 252
 253         /**
 254          * Fetches the first user id from the receiver array
 255          *
 256          * @param array $receivers Array with receivers
 257          * @return integer user id;
 258          */
 259         public static function getFirstUserFromReceivers($receivers)
 260         {
 261                 foreach ($receivers as $receiver) {
 262                         if (!empty($receiver)) {
 263                                 return $receiver;
 264                         }
 265                 }
 266                 return 0;
 267         }
 268
 269         /**
 270          * Store the unprocessed data into the conversation table
 271          * This has to be done outside the regular function,
 272          * since we store everything - not only item posts.
 273          *
 274          * @param array  $activity Array with activity data
 275          * @param string $body     The raw message
 276          * @throws \Exception
 277          */
 278         private static function storeConversation($activity, $body)
 279         {
 280                 if (empty($body) || empty($activity['id'])) {
 281                         return;
 282                 }
 283
 284                 $conversation = [
 285                         'protocol' => Conversation::PARCEL_ACTIVITYPUB,
 286                         'item-uri' => $activity['id'],
 287                         'reply-to-uri' => defaults($activity, 'reply-to-id', ''),
 288                         'conversation-href' => defaults($activity, 'context', ''),
 289                         'conversation-uri' => defaults($activity, 'conversation', ''),
 290                         'source' => $body,
 291                         'received' => DateTimeFormat::utcNow()];
 292
 293                 DBA::insert('conversation', $conversation, true);
 294         }
 295
 296         /**
 297          * Processes the activity object
 298          *
 299          * @param array   $activity     Array with activity data
 300          * @param string  $body
 301          * @param integer $uid          User ID
 302          * @param boolean $trust_source Do we trust the source?
 303          * @throws \Exception
 304          */
 305         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false)
 306         {
 307                 $type = JsonLD::fetchElement($activity, '@type');
 308                 if (!$type) {
 309                         Logger::log('Empty type', Logger::DEBUG);
 310                         return;
 311                 }
 312
 313                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 314                         Logger::log('Empty object', Logger::DEBUG);
 315                         return;
 316                 }
 317
 318                 if (!JsonLD::fetchElement($activity, 'as:actor', '@id')) {
 319                         Logger::log('Empty actor', Logger::DEBUG);
 320                         return;
 321
 322                 }
 323
 324                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
 325                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
 326                         $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 327                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 328                         $trust_source = ($actor == $attributed_to);
 329                         if (!$trust_source) {
 330                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
 331                         }
 332                 }
 333
 334                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 335                 $object_data = self::prepareObjectData($activity, $uid, $trust_source);
 336                 if (empty($object_data)) {
 337                         Logger::log('No object data found', Logger::DEBUG);
 338                         return;
 339                 }
 340
 341                 if (!$trust_source) {
 342                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
 343                         return;
 344                 }
 345
 346                 // Only store content related stuff - and no announces, since they possibly overwrite the original content
 347                 if (in_array($object_data['object_type'], self::CONTENT_TYPES) && ($type != 'as:Announce')) {
 348                         self::storeConversation($object_data, $body);
 349                 }
 350
 351                 // Internal flag for thread completion. See Processor.php
 352                 if (!empty($activity['thread-completion'])) {
 353                         $object_data['thread-completion'] = $activity['thread-completion'];
 354                 }
 355
 356                 switch ($type) {
 357                         case 'as:Create':
 358                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 359                                         ActivityPub\Processor::createItem($object_data);
 360                                 }
 361                                 break;
 362
 363                         case 'as:Announce':
 364                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 365                                         $profile = APContact::getByURL($object_data['actor']);
 366                                         if ($profile['type'] == 'Person') {
 367                                                 // Reshared posts from persons appear as summary at the bottom
 368                                                 // If this isn't set, then a single reshare appears on top. This is used for groups.
 369                                                 $object_data['thread-completion'] = true;
 370                                         }
 371                                         ActivityPub\Processor::createItem($object_data);
 372
 373                                         // Add the bottom reshare information only for persons
 374                                         if ($profile['type'] == 'Person') {
 375                                                 $announce_object_data = self::processObject($activity);
 376                                                 $announce_object_data['name'] = $type;
 377                                                 $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 378                                                 $announce_object_data['object_id'] = $object_data['object_id'];
 379                                                 $announce_object_data['object_type'] = $object_data['object_type'];
 380
 381                                                 ActivityPub\Processor::createActivity($announce_object_data, ACTIVITY2_ANNOUNCE);
 382                                         }
 383                                 }
 384                                 break;
 385
 386                         case 'as:Like':
 387                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 388                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_LIKE);
 389                                 }
 390                                 break;
 391
 392                         case 'as:Dislike':
 393                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 394                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_DISLIKE);
 395                                 }
 396                                 break;
 397
 398                         case 'as:TentativeAccept':
 399                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 400                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDMAYBE);
 401                                 }
 402                                 break;
 403
 404                         case 'as:Update':
 405                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 406                                         ActivityPub\Processor::updateItem($object_data);
 407                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 408                                         ActivityPub\Processor::updatePerson($object_data);
 409                                 }
 410                                 break;
 411
 412                         case 'as:Delete':
 413                                 if ($object_data['object_type'] == 'as:Tombstone') {
 414                                         ActivityPub\Processor::deleteItem($object_data);
 415                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 416                                         ActivityPub\Processor::deletePerson($object_data);
 417                                 }
 418                                 break;
 419
 420                         case 'as:Follow':
 421                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 422                                         ActivityPub\Processor::followUser($object_data);
 423                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 424                                         $object_data['reply-to-id'] = $object_data['object_id'];
 425                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_FOLLOW);
 426                                 }
 427                                 break;
 428
 429                         case 'as:Accept':
 430                                 if ($object_data['object_type'] == 'as:Follow') {
 431                                         ActivityPub\Processor::acceptFollowUser($object_data);
 432                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 433                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTEND);
 434                                 }
 435                                 break;
 436
 437                         case 'as:Reject':
 438                                 if ($object_data['object_type'] == 'as:Follow') {
 439                                         ActivityPub\Processor::rejectFollowUser($object_data);
 440                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 441                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDNO);
 442                                 }
 443                                 break;
 444
 445                         case 'as:Undo':
 446                                 if (($object_data['object_type'] == 'as:Follow') &&
 447                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 448                                         ActivityPub\Processor::undoFollowUser($object_data);
 449                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 450                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 451                                         ActivityPub\Processor::rejectFollowUser($object_data);
 452                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 453                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 454                                         ActivityPub\Processor::undoActivity($object_data);
 455                                 }
 456                                 break;
 457
 458                         default:
 459                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 460                                 break;
 461                 }
 462         }
 463
 464         /**
 465          * Fetch the receiver list from an activity array
 466          *
 467          * @param array  $activity
 468          * @param string $actor
 469          * @param array  $tags
 470          *
 471          * @return array with receivers (user id)
 472          * @throws \Exception
 473          */
 474         private static function getReceivers($activity, $actor, $tags = [])
 475         {
 476                 $receivers = [];
 477
 478                 // When it is an answer, we inherite the receivers from the parent
 479                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 480                 if (!empty($replyto)) {
 481                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 482                         while ($parent = Item::fetch($parents)) {
 483                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 484                         }
 485                 }
 486
 487                 if (!empty($actor)) {
 488                         $profile = APContact::getByURL($actor);
 489                         $followers = defaults($profile, 'followers', '');
 490
 491                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 492                 } else {
 493                         Logger::log('Empty actor', Logger::DEBUG);
 494                         $followers = '';
 495                 }
 496
 497                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 498                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 499                         if (empty($receiver_list)) {
 500                                 continue;
 501                         }
 502
 503                         foreach ($receiver_list as $receiver) {
 504                                 if ($receiver == self::PUBLIC_COLLECTION) {
 505                                         $receivers['uid:0'] = 0;
 506                                 }
 507
 508                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 509                                         // This will most likely catch all OStatus connections to Mastodon
 510                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 511                                                 , 'archive' => false, 'pending' => false];
 512                                         $contacts = DBA::select('contact', ['uid'], $condition);
 513                                         while ($contact = DBA::fetch($contacts)) {
 514                                                 if ($contact['uid'] != 0) {
 515                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 516                                                 }
 517                                         }
 518                                         DBA::close($contacts);
 519                                 }
 520
 521                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 522                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 523                                         continue;
 524                                 }
 525
 526                                 // Fetching all directly addressed receivers
 527                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 528                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 529                                 if (!DBA::isResult($contact)) {
 530                                         continue;
 531                                 }
 532
 533                                 // Check if the potential receiver is following the actor
 534                                 // Exception: The receiver is targetted via "to" or this is a comment
 535                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 536                                         $networks = [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::DIASPORA, Protocol::OSTATUS];
 537                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 538                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 539
 540                                         // Forum posts are only accepted from forum contacts
 541                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 542                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 543                                         }
 544
 545                                         if (!DBA::exists('contact', $condition)) {
 546                                                 continue;
 547                                         }
 548                                 }
 549
 550                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 551                         }
 552                 }
 553
 554                 self::switchContacts($receivers, $actor);
 555
 556                 return $receivers;
 557         }
 558
 559         /**
 560          * Fetch the receiver list of a given actor
 561          *
 562          * @param string $actor
 563          * @param array  $tags
 564          *
 565          * @return array with receivers (user id)
 566          * @throws \Exception
 567          */
 568         public static function getReceiverForActor($actor, $tags)
 569         {
 570                 $receivers = [];
 571                 $networks = [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::DIASPORA, Protocol::OSTATUS];
 572                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 573                         'network' => $networks, 'archive' => false, 'pending' => false];
 574                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 575                 while ($contact = DBA::fetch($contacts)) {
 576                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 577                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 578                         }
 579                 }
 580                 DBA::close($contacts);
 581                 return $receivers;
 582         }
 583
 584         /**
 585          * Tests if the contact is a valid receiver for this actor
 586          *
 587          * @param array  $contact
 588          * @param string $actor
 589          * @param array  $tags
 590          *
 591          * @return bool with receivers (user id)
 592          * @throws \Exception
 593          */
 594         private static function isValidReceiverForActor($contact, $actor, $tags)
 595         {
 596                 // Public contacts are no valid receiver
 597                 if ($contact['uid'] == 0) {
 598                         return false;
 599                 }
 600
 601                 // Are we following the contact? Then this is a valid receiver
 602                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 603                         return true;
 604                 }
 605
 606                 // When the possible receiver isn't a community, then it is no valid receiver
 607                 $owner = User::getOwnerDataById($contact['uid']);
 608                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 609                         return false;
 610                 }
 611
 612                 // Is the community account tagged?
 613                 foreach ($tags as $tag) {
 614                         if ($tag['type'] != 'Mention') {
 615                                 continue;
 616                         }
 617
 618                         if ($tag['href'] == $owner['url']) {
 619                                 return true;
 620                         }
 621                 }
 622
 623                 return false;
 624         }
 625
 626         /**
 627          * Switches existing contacts to ActivityPub
 628          *
 629          * @param integer $cid Contact ID
 630          * @param integer $uid User ID
 631          * @param string  $url Profile URL
 632          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 633          * @throws \ImagickException
 634          */
 635         public static function switchContact($cid, $uid, $url)
 636         {
 637                 $profile = ActivityPub::probeProfile($url);
 638                 if (empty($profile)) {
 639                         return;
 640                 }
 641
 642                 Logger::log('Switch contact ' . $cid . ' (' . $profile['url'] . ') for user ' . $uid . ' to ActivityPub');
 643
 644                 $photo = defaults($profile, 'photo', null);
 645                 unset($profile['photo']);
 646                 unset($profile['baseurl']);
 647                 unset($profile['guid']);
 648
 649                 $profile['nurl'] = Strings::normaliseLink($profile['url']);
 650                 DBA::update('contact', $profile, ['id' => $cid]);
 651
 652                 Contact::updateAvatar($photo, $uid, $cid);
 653
 654                 // Send a new follow request to be sure that the connection still exists
 655                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND]])) {
 656                         ActivityPub\Transmitter::sendActivity('Follow', $profile['url'], $uid);
 657                         Logger::log('Send a new follow request to ' . $profile['url'] . ' for user ' . $uid, Logger::DEBUG);
 658                 }
 659         }
 660
 661         /**
 662          *
 663          *
 664          * @param $receivers
 665          * @param $actor
 666          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 667          * @throws \ImagickException
 668          */
 669         private static function switchContacts($receivers, $actor)
 670         {
 671                 if (empty($actor)) {
 672                         return;
 673                 }
 674
 675                 foreach ($receivers as $receiver) {
 676                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 677                         if (DBA::isResult($contact)) {
 678                                 self::switchContact($contact['id'], $receiver, $actor);
 679                         }
 680
 681                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 682                         if (DBA::isResult($contact)) {
 683                                 self::switchContact($contact['id'], $receiver, $actor);
 684                         }
 685                 }
 686         }
 687
 688         /**
 689          *
 690          *
 691          * @param       $object_data
 692          * @param array $activity
 693          *
 694          * @return mixed
 695          */
 696         private static function addActivityFields($object_data, $activity)
 697         {
 698                 if (!empty($activity['published']) && empty($object_data['published'])) {
 699                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 700                 }
 701
 702                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 703                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 704                 }
 705
 706                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 707                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 708
 709                 return $object_data;
 710         }
 711
 712         /**
 713          * Fetches the object data from external ressources if needed
 714          *
 715          * @param string  $object_id    Object ID of the the provided object
 716          * @param array   $object       The provided object array
 717          * @param boolean $trust_source Do we trust the provided object?
 718          * @param integer $uid          User ID for the signature that we use to fetch data
 719          *
 720          * @return array with trusted and valid object data
 721          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 722          * @throws \ImagickException
 723          */
 724         private static function fetchObject($object_id, $object = [], $trust_source = false, $uid = 0)
 725         {
 726                 // By fetching the type we check if the object is complete.
 727                 $type = JsonLD::fetchElement($object, '@type');
 728
 729                 if (!$trust_source || empty($type)) {
 730                         $data = ActivityPub::fetchContent($object_id, $uid);
 731                         if (!empty($data)) {
 732                                 $object = JsonLD::compact($data);
 733                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 734                         } else {
 735                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 736
 737                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 738                                 if (!DBA::isResult($item)) {
 739                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 740                                         return false;
 741                                 }
 742                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 743                                 $data = ActivityPub\Transmitter::createNote($item);
 744                                 $object = JsonLD::compact($data);
 745                         }
 746                 } else {
 747                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 748                 }
 749
 750                 $type = JsonLD::fetchElement($object, '@type');
 751
 752                 if (empty($type)) {
 753                         Logger::log('Empty type', Logger::DEBUG);
 754                         return false;
 755                 }
 756
 757                 if (in_array($type, self::CONTENT_TYPES)) {
 758                         return self::processObject($object);
 759                 }
 760
 761                 if ($type == 'as:Announce') {
 762                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
 763                         if (empty($object_id)) {
 764                                 return false;
 765                         }
 766                         return self::fetchObject($object_id, [], false, $uid);
 767                 }
 768
 769                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 770         }
 771
 772         /**
 773          * Convert tags from JSON-LD format into a simplified format
 774          *
 775          * @param array $tags Tags in JSON-LD format
 776          *
 777          * @return array with tags in a simplified format
 778          */
 779         private static function processTags($tags)
 780         {
 781                 $taglist = [];
 782
 783                 if (empty($tags)) {
 784                         return [];
 785                 }
 786
 787                 foreach ($tags as $tag) {
 788                         if (empty($tag)) {
 789                                 continue;
 790                         }
 791
 792                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 793                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
 794                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
 795
 796                         if (empty($element['type'])) {
 797                                 continue;
 798                         }
 799
 800                         $taglist[] = $element;
 801                 }
 802                 return $taglist;
 803         }
 804
 805         /**
 806          * Convert emojis from JSON-LD format into a simplified format
 807          *
 808          * @param $emojis
 809          * @return array with emojis in a simplified format
 810          */
 811         private static function processEmojis($emojis)
 812         {
 813                 $emojilist = [];
 814
 815                 if (empty($emojis)) {
 816                         return [];
 817                 }
 818
 819                 foreach ($emojis as $emoji) {
 820                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
 821                                 continue;
 822                         }
 823
 824                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
 825                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
 826                                 'href' => $url];
 827
 828                         $emojilist[] = $element;
 829                 }
 830                 return $emojilist;
 831         }
 832
 833         /**
 834          * Convert attachments from JSON-LD format into a simplified format
 835          *
 836          * @param array $attachments Attachments in JSON-LD format
 837          *
 838          * @return array with attachmants in a simplified format
 839          */
 840         private static function processAttachments($attachments)
 841         {
 842                 $attachlist = [];
 843
 844                 if (empty($attachments)) {
 845                         return [];
 846                 }
 847
 848                 foreach ($attachments as $attachment) {
 849                         if (empty($attachment)) {
 850                                 continue;
 851                         }
 852
 853                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 854                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
 855                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
 856                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')];
 857                 }
 858                 return $attachlist;
 859         }
 860
 861         /**
 862          * Fetches data from the object part of an activity
 863          *
 864          * @param array $object
 865          *
 866          * @return array
 867          * @throws \Exception
 868          */
 869         private static function processObject($object)
 870         {
 871                 if (!JsonLD::fetchElement($object, '@id')) {
 872                         return false;
 873                 }
 874
 875                 $object_data = [];
 876                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 877                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 878                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
 879
 880                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
 881                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
 882                         $object_data['reply-to-id'] = $object_data['id'];
 883                 }
 884
 885                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 886                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 887
 888                 if (empty($object_data['updated'])) {
 889                         $object_data['updated'] = $object_data['published'];
 890                 }
 891
 892                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 893                         $object_data['published'] = $object_data['updated'];
 894                 }
 895
 896                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
 897                 if (empty($actor)) {
 898                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
 899                 }
 900
 901                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
 902                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
 903                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
 904                 $object_data['actor'] = $object_data['author'] = $actor;
 905                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
 906                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
 907                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 908                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
 909                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
 910                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
 911                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 912                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 913                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
 914                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
 915                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
 916                 $object_data['location'] = JsonLD::fetchElement($object_data, 'location', '@value');
 917                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
 918                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
 919                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
 920                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
 921                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
 922                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
 923                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji'));
 924                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
 925                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
 926                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
 927
 928                 // Special treatment for Hubzilla links
 929                 if (is_array($object_data['alternate-url'])) {
 930                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
 931
 932                         if (!is_string($object_data['alternate-url'])) {
 933                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
 934                         }
 935                 }
 936
 937                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags']);
 938
 939                 // Test if it is an answer to a mail
 940                 if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 941                         $object_data['directmessage'] = true;
 942                 }
 943
 944                 // Common object data:
 945
 946                 // Unhandled
 947                 // @context, type, actor, signature, mediaType, duration, replies, icon
 948
 949                 // Also missing: (Defined in the standard, but currently unused)
 950                 // audience, preview, endTime, startTime, image
 951
 952                 // Data in Notes:
 953
 954                 // Unhandled
 955                 // contentMap, announcement_count, announcements, context_id, likes, like_count
 956                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
 957
 958                 // Data in video:
 959
 960                 // To-Do?
 961                 // category, licence, language, commentsEnabled
 962
 963                 // Unhandled
 964                 // views, waitTranscoding, state, support, subtitleLanguage
 965                 // likes, dislikes, shares, comments
 966
 967                 return $object_data;
 968         }
 969 }