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\Content\Text\HTML;
   9 use Friendica\Content\Text\Markdown;
  10 use Friendica\Core\Logger;
  11 use Friendica\Core\Protocol;
  12 use Friendica\Model\Contact;
  13 use Friendica\Model\APContact;
  14 use Friendica\Model\Conversation;
  15 use Friendica\Model\Item;
  16 use Friendica\Model\User;
  17 use Friendica\Protocol\Activity;
  18 use Friendica\Protocol\ActivityPub;
  19 use Friendica\Util\DateTimeFormat;
  20 use Friendica\Util\HTTPSignature;
  21 use Friendica\Util\JsonLD;
  22 use Friendica\Util\LDSignature;
  23 use Friendica\Util\Strings;
  24
  25 /**
  26  * @brief ActivityPub Receiver Protocol class
  27  *
  28  * To-Do:
  29  * - Undo Announce
  30  *
  31  * Check what this is meant to do:
  32  * - Add
  33  * - Block
  34  * - Flag
  35  * - Remove
  36  * - Undo Block
  37  */
  38 class Receiver
  39 {
  40         const PUBLIC_COLLECTION = 'as:Public';
  41         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  42         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event'];
  43         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  44
  45         /**
  46          * Checks if the web request is done for the AP protocol
  47          *
  48          * @return bool is it AP?
  49          */
  50         public static function isRequest()
  51         {
  52                 return stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/activity+json') ||
  53                         stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/ld+json');
  54         }
  55
  56         /**
  57          * Checks incoming message from the inbox
  58          *
  59          * @param         $body
  60          * @param         $header
  61          * @param integer $uid User ID
  62          * @throws \Exception
  63          */
  64         public static function processInbox($body, $header, $uid)
  65         {
  66                 $http_signer = HTTPSignature::getSigner($body, $header);
  67                 if (empty($http_signer)) {
  68                         Logger::warning('Invalid HTTP signature, message will be discarded.');
  69                         return;
  70                 } else {
  71                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
  72                 }
  73
  74                 $activity = json_decode($body, true);
  75
  76                 if (empty($activity)) {
  77                         Logger::warning('Invalid body.');
  78                         return;
  79                 }
  80
  81                 $ldactivity = JsonLD::compact($activity);
  82
  83                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor', '@id');
  84
  85                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
  86
  87                 if (LDSignature::isSigned($activity)) {
  88                         $ld_signer = LDSignature::getSigner($activity);
  89                         if (empty($ld_signer)) {
  90                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
  91                         }
  92                         if (!empty($ld_signer && ($actor == $http_signer))) {
  93                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
  94                                 $trust_source = true;
  95                         } elseif (!empty($ld_signer)) {
  96                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
  97                                 $trust_source = true;
  98                         } elseif ($actor == $http_signer) {
  99                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
 100                                 $trust_source = true;
 101                         } else {
 102                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
 103                                 $trust_source = false;
 104                         }
 105                 } elseif ($actor == $http_signer) {
 106                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
 107                         $trust_source = true;
 108                 } else {
 109                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
 110                         $trust_source = false;
 111                 }
 112
 113                 self::processActivity($ldactivity, $body, $uid, $trust_source);
 114         }
 115
 116         /**
 117          * Fetches the object type for a given object id
 118          *
 119          * @param array   $activity
 120          * @param string  $object_id Object ID of the the provided object
 121          * @param integer $uid       User ID
 122          *
 123          * @return string with object type
 124          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 125          * @throws \ImagickException
 126          */
 127         private static function fetchObjectType($activity, $object_id, $uid = 0)
 128         {
 129                 if (!empty($activity['as:object'])) {
 130                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 131                         if (!empty($object_type)) {
 132                                 return $object_type;
 133                         }
 134                 }
 135
 136                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 137                         // We just assume "note" since it doesn't make a difference for the further processing
 138                         return 'as:Note';
 139                 }
 140
 141                 $profile = APContact::getByURL($object_id);
 142                 if (!empty($profile['type'])) {
 143                         return 'as:' . $profile['type'];
 144                 }
 145
 146                 $data = ActivityPub::fetchContent($object_id, $uid);
 147                 if (!empty($data)) {
 148                         $object = JsonLD::compact($data);
 149                         $type = JsonLD::fetchElement($object, '@type');
 150                         if (!empty($type)) {
 151                                 return $type;
 152                         }
 153                 }
 154
 155                 return null;
 156         }
 157
 158         /**
 159          * Prepare the object array
 160          *
 161          * @param array   $activity
 162          * @param integer $uid User ID
 163          * @param         $trust_source
 164          *
 165          * @return array with object data
 166          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 167          * @throws \ImagickException
 168          */
 169         private static function prepareObjectData($activity, $uid, &$trust_source)
 170         {
 171                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 172                 if (empty($actor)) {
 173                         Logger::log('Empty actor', Logger::DEBUG);
 174                         return [];
 175                 }
 176
 177                 $type = JsonLD::fetchElement($activity, '@type');
 178
 179                 // Fetch all receivers from to, cc, bto and bcc
 180                 $receivers = self::getReceivers($activity, $actor);
 181
 182                 // When it is a delivery to a personal inbox we add that user to the receivers
 183                 if (!empty($uid)) {
 184                         $additional = ['uid:' . $uid => $uid];
 185                         $receivers = array_merge($receivers, $additional);
 186                 } else {
 187                         // We possibly need some user to fetch private content,
 188                         // so we fetch the first out ot the list.
 189                         $uid = self::getFirstUserFromReceivers($receivers);
 190                 }
 191
 192                 Logger::log('Receivers: ' . $uid . ' - ' . json_encode($receivers), Logger::DEBUG);
 193
 194                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 195                 if (empty($object_id)) {
 196                         Logger::log('No object found', Logger::DEBUG);
 197                         return [];
 198                 }
 199
 200                 if (!is_string($object_id)) {
 201                         Logger::info('Invalid object id', ['object' => $object_id]);
 202                         return [];
 203                 }
 204
 205                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
 206
 207                 // Fetch the content only on activities where this matters
 208                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 209                         if ($type == 'as:Announce') {
 210                                 $trust_source = false;
 211                         }
 212                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $uid);
 213                         if (empty($object_data)) {
 214                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
 215                                 return [];
 216                         }
 217                         $object_data['object_id'] = $object_id;
 218
 219                         // Test if it is an answer to a mail
 220                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 221                                 $object_data['directmessage'] = true;
 222                         } else {
 223                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 224                         }
 225
 226                         // We had been able to retrieve the object data - so we can trust the source
 227                         $trust_source = true;
 228                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 229                         // Create a mostly empty array out of the activity data (instead of the object).
 230                         // This way we later don't have to check for the existence of ech individual array element.
 231                         $object_data = self::processObject($activity);
 232                         $object_data['name'] = $type;
 233                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 234                         $object_data['object_id'] = $object_id;
 235                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 236                 } elseif (in_array($type, ['as:Add'])) {
 237                         $object_data = [];
 238                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 239                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 240                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 241                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 242                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 243                 } else {
 244                         $object_data = [];
 245                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 246                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 247                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 248                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 249                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 250
 251                         // An Undo is done on the object of an object, so we need that type as well
 252                         if ($type == 'as:Undo') {
 253                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 254                         }
 255                 }
 256
 257                 $object_data = self::addActivityFields($object_data, $activity);
 258
 259                 if (empty($object_data['object_type'])) {
 260                         $object_data['object_type'] = $object_type;
 261                 }
 262
 263                 $object_data['type'] = $type;
 264                 $object_data['actor'] = $actor;
 265                 $object_data['item_receiver'] = $receivers;
 266                 $object_data['receiver'] = array_merge($object_data['receiver'] ?? [], $receivers);
 267
 268                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 269
 270                 return $object_data;
 271         }
 272
 273         /**
 274          * Fetches the first user id from the receiver array
 275          *
 276          * @param array $receivers Array with receivers
 277          * @return integer user id;
 278          */
 279         public static function getFirstUserFromReceivers($receivers)
 280         {
 281                 foreach ($receivers as $receiver) {
 282                         if (!empty($receiver)) {
 283                                 return $receiver;
 284                         }
 285                 }
 286                 return 0;
 287         }
 288
 289         /**
 290          * Store the unprocessed data into the conversation table
 291          * This has to be done outside the regular function,
 292          * since we store everything - not only item posts.
 293          *
 294          * @param array  $activity Array with activity data
 295          * @param string $body     The raw message
 296          * @throws \Exception
 297          */
 298         private static function storeConversation($activity, $body)
 299         {
 300                 if (empty($body) || empty($activity['id'])) {
 301                         return;
 302                 }
 303
 304                 $conversation = [
 305                         'protocol' => Conversation::PARCEL_ACTIVITYPUB,
 306                         'item-uri' => $activity['id'],
 307                         'reply-to-uri' => $activity['reply-to-id'] ?? '',
 308                         'conversation-href' => $activity['context'] ?? '',
 309                         'conversation-uri' => $activity['conversation'] ?? '',
 310                         'source' => $body,
 311                         'received' => DateTimeFormat::utcNow()];
 312
 313                 DBA::insert('conversation', $conversation, true);
 314         }
 315
 316         /**
 317          * Processes the activity object
 318          *
 319          * @param array   $activity     Array with activity data
 320          * @param string  $body
 321          * @param integer $uid          User ID
 322          * @param boolean $trust_source Do we trust the source?
 323          * @throws \Exception
 324          */
 325         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false)
 326         {
 327                 $type = JsonLD::fetchElement($activity, '@type');
 328                 if (!$type) {
 329                         Logger::log('Empty type', Logger::DEBUG);
 330                         return;
 331                 }
 332
 333                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 334                         Logger::log('Empty object', Logger::DEBUG);
 335                         return;
 336                 }
 337
 338                 if (!JsonLD::fetchElement($activity, 'as:actor', '@id')) {
 339                         Logger::log('Empty actor', Logger::DEBUG);
 340                         return;
 341
 342                 }
 343
 344                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
 345                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
 346                         $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 347                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 348                         $trust_source = ($actor == $attributed_to);
 349                         if (!$trust_source) {
 350                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
 351                         }
 352                 }
 353
 354                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 355                 $object_data = self::prepareObjectData($activity, $uid, $trust_source);
 356                 if (empty($object_data)) {
 357                         Logger::log('No object data found', Logger::DEBUG);
 358                         return;
 359                 }
 360
 361                 if (!$trust_source) {
 362                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
 363                         return;
 364                 }
 365
 366                 // Only store content related stuff - and no announces, since they possibly overwrite the original content
 367                 if (in_array($object_data['object_type'], self::CONTENT_TYPES) && ($type != 'as:Announce')) {
 368                         self::storeConversation($object_data, $body);
 369                 }
 370
 371                 // Internal flag for thread completion. See Processor.php
 372                 if (!empty($activity['thread-completion'])) {
 373                         $object_data['thread-completion'] = $activity['thread-completion'];
 374                 }
 375
 376                 switch ($type) {
 377                         case 'as:Create':
 378                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 379                                         ActivityPub\Processor::createItem($object_data);
 380                                 }
 381                                 break;
 382
 383                         case 'as:Add':
 384                                 if ($object_data['object_type'] == 'as:tag') {
 385                                         ActivityPub\Processor::addTag($object_data);
 386                                 }
 387                                 break;
 388
 389                         case 'as:Announce':
 390                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 391                                         $profile = APContact::getByURL($object_data['actor']);
 392                                         // Reshared posts from persons appear as summary at the bottom
 393                                         // If this isn't set, then a single reshare appears on top. This is used for groups.
 394                                         $object_data['thread-completion'] = ($profile['type'] != 'Group');
 395
 396                                         ActivityPub\Processor::createItem($object_data);
 397
 398                                         // Add the bottom reshare information only for persons
 399                                         if ($profile['type'] != 'Group') {
 400                                                 $announce_object_data = self::processObject($activity);
 401                                                 $announce_object_data['name'] = $type;
 402                                                 $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 403                                                 $announce_object_data['object_id'] = $object_data['object_id'];
 404                                                 $announce_object_data['object_type'] = $object_data['object_type'];
 405
 406                                                 ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 407                                         }
 408                                 }
 409                                 break;
 410
 411                         case 'as:Like':
 412                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 413                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 414                                 }
 415                                 break;
 416
 417                         case 'as:Dislike':
 418                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 419                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 420                                 }
 421                                 break;
 422
 423                         case 'as:TentativeAccept':
 424                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 425                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 426                                 }
 427                                 break;
 428
 429                         case 'as:Update':
 430                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 431                                         ActivityPub\Processor::updateItem($object_data);
 432                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 433                                         ActivityPub\Processor::updatePerson($object_data);
 434                                 }
 435                                 break;
 436
 437                         case 'as:Delete':
 438                                 if ($object_data['object_type'] == 'as:Tombstone') {
 439                                         ActivityPub\Processor::deleteItem($object_data);
 440                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 441                                         ActivityPub\Processor::deletePerson($object_data);
 442                                 }
 443                                 break;
 444
 445                         case 'as:Follow':
 446                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 447                                         ActivityPub\Processor::followUser($object_data);
 448                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 449                                         $object_data['reply-to-id'] = $object_data['object_id'];
 450                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 451                                 }
 452                                 break;
 453
 454                         case 'as:Accept':
 455                                 if ($object_data['object_type'] == 'as:Follow') {
 456                                         ActivityPub\Processor::acceptFollowUser($object_data);
 457                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 458                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 459                                 }
 460                                 break;
 461
 462                         case 'as:Reject':
 463                                 if ($object_data['object_type'] == 'as:Follow') {
 464                                         ActivityPub\Processor::rejectFollowUser($object_data);
 465                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 466                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 467                                 }
 468                                 break;
 469
 470                         case 'as:Undo':
 471                                 if (($object_data['object_type'] == 'as:Follow') &&
 472                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 473                                         ActivityPub\Processor::undoFollowUser($object_data);
 474                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 475                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 476                                         ActivityPub\Processor::rejectFollowUser($object_data);
 477                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 478                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 479                                         ActivityPub\Processor::undoActivity($object_data);
 480                                 }
 481                                 break;
 482
 483                         default:
 484                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 485                                 break;
 486                 }
 487         }
 488
 489         /**
 490          * Fetch the receiver list from an activity array
 491          *
 492          * @param array  $activity
 493          * @param string $actor
 494          * @param array  $tags
 495          *
 496          * @return array with receivers (user id)
 497          * @throws \Exception
 498          */
 499         private static function getReceivers($activity, $actor, $tags = [])
 500         {
 501                 $receivers = [];
 502
 503                 // When it is an answer, we inherite the receivers from the parent
 504                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 505                 if (!empty($replyto)) {
 506                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 507                         while ($parent = Item::fetch($parents)) {
 508                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 509                         }
 510                 }
 511
 512                 if (!empty($actor)) {
 513                         $profile = APContact::getByURL($actor);
 514                         $followers = $profile['followers'] ?? '';
 515
 516                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 517                 } else {
 518                         Logger::log('Empty actor', Logger::DEBUG);
 519                         $followers = '';
 520                 }
 521
 522                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 523                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 524                         if (empty($receiver_list)) {
 525                                 continue;
 526                         }
 527
 528                         foreach ($receiver_list as $receiver) {
 529                                 if ($receiver == self::PUBLIC_COLLECTION) {
 530                                         $receivers['uid:0'] = 0;
 531                                 }
 532
 533                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 534                                         // This will most likely catch all OStatus connections to Mastodon
 535                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 536                                                 , 'archive' => false, 'pending' => false];
 537                                         $contacts = DBA::select('contact', ['uid'], $condition);
 538                                         while ($contact = DBA::fetch($contacts)) {
 539                                                 if ($contact['uid'] != 0) {
 540                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 541                                                 }
 542                                         }
 543                                         DBA::close($contacts);
 544                                 }
 545
 546                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 547                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 548                                         continue;
 549                                 }
 550
 551                                 // Fetching all directly addressed receivers
 552                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 553                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 554                                 if (!DBA::isResult($contact)) {
 555                                         continue;
 556                                 }
 557
 558                                 // Check if the potential receiver is following the actor
 559                                 // Exception: The receiver is targetted via "to" or this is a comment
 560                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 561                                         $networks = Protocol::FEDERATED;
 562                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 563                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 564
 565                                         // Forum posts are only accepted from forum contacts
 566                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 567                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 568                                         }
 569
 570                                         if (!DBA::exists('contact', $condition)) {
 571                                                 continue;
 572                                         }
 573                                 }
 574
 575                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 576                         }
 577                 }
 578
 579                 self::switchContacts($receivers, $actor);
 580
 581                 return $receivers;
 582         }
 583
 584         /**
 585          * Fetch the receiver list of a given actor
 586          *
 587          * @param string $actor
 588          * @param array  $tags
 589          *
 590          * @return array with receivers (user id)
 591          * @throws \Exception
 592          */
 593         public static function getReceiverForActor($actor, $tags)
 594         {
 595                 $receivers = [];
 596                 $networks = Protocol::FEDERATED;
 597                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 598                         'network' => $networks, 'archive' => false, 'pending' => false];
 599                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 600                 while ($contact = DBA::fetch($contacts)) {
 601                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 602                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 603                         }
 604                 }
 605                 DBA::close($contacts);
 606                 return $receivers;
 607         }
 608
 609         /**
 610          * Tests if the contact is a valid receiver for this actor
 611          *
 612          * @param array  $contact
 613          * @param string $actor
 614          * @param array  $tags
 615          *
 616          * @return bool with receivers (user id)
 617          * @throws \Exception
 618          */
 619         private static function isValidReceiverForActor($contact, $actor, $tags)
 620         {
 621                 // Public contacts are no valid receiver
 622                 if ($contact['uid'] == 0) {
 623                         return false;
 624                 }
 625
 626                 // Are we following the contact? Then this is a valid receiver
 627                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 628                         return true;
 629                 }
 630
 631                 // When the possible receiver isn't a community, then it is no valid receiver
 632                 $owner = User::getOwnerDataById($contact['uid']);
 633                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 634                         return false;
 635                 }
 636
 637                 // Is the community account tagged?
 638                 foreach ($tags as $tag) {
 639                         if ($tag['type'] != 'Mention') {
 640                                 continue;
 641                         }
 642
 643                         if ($tag['href'] == $owner['url']) {
 644                                 return true;
 645                         }
 646                 }
 647
 648                 return false;
 649         }
 650
 651         /**
 652          * Switches existing contacts to ActivityPub
 653          *
 654          * @param integer $cid Contact ID
 655          * @param integer $uid User ID
 656          * @param string  $url Profile URL
 657          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 658          * @throws \ImagickException
 659          */
 660         public static function switchContact($cid, $uid, $url)
 661         {
 662                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 663                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 664                         return;
 665                 }
 666
 667                 if (Contact::updateFromProbe($cid, '', true)) {
 668                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 669                 }
 670
 671                 // Send a new follow request to be sure that the connection still exists
 672                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 673                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 674                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 675                 }
 676         }
 677
 678         /**
 679          *
 680          *
 681          * @param $receivers
 682          * @param $actor
 683          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 684          * @throws \ImagickException
 685          */
 686         private static function switchContacts($receivers, $actor)
 687         {
 688                 if (empty($actor)) {
 689                         return;
 690                 }
 691
 692                 foreach ($receivers as $receiver) {
 693                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 694                         if (DBA::isResult($contact)) {
 695                                 self::switchContact($contact['id'], $receiver, $actor);
 696                         }
 697
 698                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 699                         if (DBA::isResult($contact)) {
 700                                 self::switchContact($contact['id'], $receiver, $actor);
 701                         }
 702                 }
 703         }
 704
 705         /**
 706          *
 707          *
 708          * @param       $object_data
 709          * @param array $activity
 710          *
 711          * @return mixed
 712          */
 713         private static function addActivityFields($object_data, $activity)
 714         {
 715                 if (!empty($activity['published']) && empty($object_data['published'])) {
 716                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 717                 }
 718
 719                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 720                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 721                 }
 722
 723                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 724                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 725
 726                 return $object_data;
 727         }
 728
 729         /**
 730          * Fetches the object data from external ressources if needed
 731          *
 732          * @param string  $object_id    Object ID of the the provided object
 733          * @param array   $object       The provided object array
 734          * @param boolean $trust_source Do we trust the provided object?
 735          * @param integer $uid          User ID for the signature that we use to fetch data
 736          *
 737          * @return array|false with trusted and valid object data
 738          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 739          * @throws \ImagickException
 740          */
 741         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
 742         {
 743                 // By fetching the type we check if the object is complete.
 744                 $type = JsonLD::fetchElement($object, '@type');
 745
 746                 if (!$trust_source || empty($type)) {
 747                         $data = ActivityPub::fetchContent($object_id, $uid);
 748                         if (!empty($data)) {
 749                                 $object = JsonLD::compact($data);
 750                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 751                         } else {
 752                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 753
 754                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 755                                 if (!DBA::isResult($item)) {
 756                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 757                                         return false;
 758                                 }
 759                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 760                                 $data = ActivityPub\Transmitter::createNote($item);
 761                                 $object = JsonLD::compact($data);
 762                         }
 763                 } else {
 764                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 765                 }
 766
 767                 $type = JsonLD::fetchElement($object, '@type');
 768
 769                 if (empty($type)) {
 770                         Logger::log('Empty type', Logger::DEBUG);
 771                         return false;
 772                 }
 773
 774                 if (in_array($type, self::CONTENT_TYPES)) {
 775                         return self::processObject($object);
 776                 }
 777
 778                 if ($type == 'as:Announce') {
 779                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
 780                         if (empty($object_id) || !is_string($object_id)) {
 781                                 return false;
 782                         }
 783                         return self::fetchObject($object_id, [], false, $uid);
 784                 }
 785
 786                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 787                 return false;
 788         }
 789
 790         /**
 791          * Convert tags from JSON-LD format into a simplified format
 792          *
 793          * @param array $tags Tags in JSON-LD format
 794          *
 795          * @return array with tags in a simplified format
 796          */
 797         private static function processTags($tags)
 798         {
 799                 $taglist = [];
 800
 801                 if (empty($tags)) {
 802                         return [];
 803                 }
 804
 805                 foreach ($tags as $tag) {
 806                         if (empty($tag)) {
 807                                 continue;
 808                         }
 809
 810                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 811                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
 812                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
 813
 814                         if (empty($element['type'])) {
 815                                 continue;
 816                         }
 817
 818                         $taglist[] = $element;
 819                 }
 820                 return $taglist;
 821         }
 822
 823         /**
 824          * Convert emojis from JSON-LD format into a simplified format
 825          *
 826          * @param $emojis
 827          * @return array with emojis in a simplified format
 828          */
 829         private static function processEmojis($emojis)
 830         {
 831                 $emojilist = [];
 832
 833                 if (empty($emojis)) {
 834                         return [];
 835                 }
 836
 837                 foreach ($emojis as $emoji) {
 838                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
 839                                 continue;
 840                         }
 841
 842                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
 843                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
 844                                 'href' => $url];
 845
 846                         $emojilist[] = $element;
 847                 }
 848                 return $emojilist;
 849         }
 850
 851         /**
 852          * Convert attachments from JSON-LD format into a simplified format
 853          *
 854          * @param array $attachments Attachments in JSON-LD format
 855          *
 856          * @return array with attachmants in a simplified format
 857          */
 858         private static function processAttachments($attachments)
 859         {
 860                 $attachlist = [];
 861
 862                 if (empty($attachments)) {
 863                         return [];
 864                 }
 865
 866                 foreach ($attachments as $attachment) {
 867                         if (empty($attachment)) {
 868                                 continue;
 869                         }
 870
 871                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 872                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
 873                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
 874                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')];
 875                 }
 876                 return $attachlist;
 877         }
 878
 879         /**
 880          * Fetch the original source or content with the "language" Markdown or HTML
 881          *
 882          * @param array $object
 883          * @param array $object_data
 884          *
 885          * @return array
 886          * @throws \Exception
 887          */
 888         private static function getSource($object, $object_data)
 889         {
 890                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 891                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 892                 if (!empty($object_data['source'])) {
 893                         return $object_data;
 894                 }
 895
 896                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
 897                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 898                 if (!empty($object_data['source'])) {
 899                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
 900                         return $object_data;
 901                 }
 902
 903                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
 904                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 905                 if (!empty($object_data['source'])) {
 906                         $object_data['source'] = HTML::toBBCode($object_data['source']);
 907                         return $object_data;
 908                 }
 909
 910                 $markdown = JsonLD::fetchElement($object, 'as:content', '@value', '@language', 'text/markdown');
 911                 if (!empty($markdown)) {
 912                         $object_data['source'] = Markdown::toBBCode($markdown);
 913                         return $object_data;
 914                 }
 915
 916                 $html = JsonLD::fetchElement($object, 'as:content', '@value', '@language', 'text/html');
 917                 if (!empty($html)) {
 918                         $object_data['source'] = HTML::toBBCode($markdown);
 919                         return $object_data;
 920                 }
 921
 922                 return $object_data;
 923         }
 924
 925         /**
 926          * Fetches data from the object part of an activity
 927          *
 928          * @param array $object
 929          *
 930          * @return array
 931          * @throws \Exception
 932          */
 933         private static function processObject($object)
 934         {
 935                 if (!JsonLD::fetchElement($object, '@id')) {
 936                         return false;
 937                 }
 938
 939                 $object_data = [];
 940                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 941                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 942                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
 943
 944                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
 945                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
 946                         $object_data['reply-to-id'] = $object_data['id'];
 947                 }
 948
 949                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 950                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 951
 952                 if (empty($object_data['updated'])) {
 953                         $object_data['updated'] = $object_data['published'];
 954                 }
 955
 956                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 957                         $object_data['published'] = $object_data['updated'];
 958                 }
 959
 960                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
 961                 if (empty($actor)) {
 962                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
 963                 }
 964
 965                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
 966                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
 967                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
 968                 $object_data['actor'] = $object_data['author'] = $actor;
 969                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
 970                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
 971                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 972                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
 973                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
 974                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
 975                 $object_data = self::getSource($object, $object_data);
 976                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
 977                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
 978                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
 979                 $object_data['location'] = JsonLD::fetchElement($object_data, 'location', '@value');
 980                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
 981                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
 982                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
 983                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
 984                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
 985                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
 986                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji'));
 987                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
 988                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
 989                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
 990
 991                 // Special treatment for Hubzilla links
 992                 if (is_array($object_data['alternate-url'])) {
 993                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
 994
 995                         if (!is_string($object_data['alternate-url'])) {
 996                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
 997                         }
 998                 }
 999
1000                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags']);
1001
1002                 // Common object data:
1003
1004                 // Unhandled
1005                 // @context, type, actor, signature, mediaType, duration, replies, icon
1006
1007                 // Also missing: (Defined in the standard, but currently unused)
1008                 // audience, preview, endTime, startTime, image
1009
1010                 // Data in Notes:
1011
1012                 // Unhandled
1013                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1014                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1015
1016                 // Data in video:
1017
1018                 // To-Do?
1019                 // category, licence, language, commentsEnabled
1020
1021                 // Unhandled
1022                 // views, waitTranscoding, state, support, subtitleLanguage
1023                 // likes, dislikes, shares, comments
1024
1025                 return $object_data;
1026         }
1027 }