src/Protocol/ActivityPub/Receiver.php

   1 <?php
   2 /**
   3  * @file src/Protocol/ActivityPub/Receiver.php
   4  */
   5 namespace Friendica\Protocol\ActivityPub;
   6
   7 use Friendica\Database\DBA;
   8 use Friendica\Core\Logger;
   9 use Friendica\Core\Protocol;
  10 use Friendica\Model\Contact;
  11 use Friendica\Model\APContact;
  12 use Friendica\Model\Conversation;
  13 use Friendica\Model\Item;
  14 use Friendica\Model\User;
  15 use Friendica\Protocol\ActivityPub;
  16 use Friendica\Util\DateTimeFormat;
  17 use Friendica\Util\HTTPSignature;
  18 use Friendica\Util\JsonLD;
  19 use Friendica\Util\LDSignature;
  20 use Friendica\Util\Strings;
  21
  22 /**
  23  * @brief ActivityPub Receiver Protocol class
  24  *
  25  * To-Do:
  26  * - Undo Announce
  27  *
  28  * Check what this is meant to do:
  29  * - Add
  30  * - Block
  31  * - Flag
  32  * - Remove
  33  * - Undo Block
  34  */
  35 class Receiver
  36 {
  37         const PUBLIC_COLLECTION = 'as:Public';
  38         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  39         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event'];
  40         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  41
  42         /**
  43          * Checks if the web request is done for the AP protocol
  44          *
  45          * @return is it AP?
  46          */
  47         public static function isRequest()
  48         {
  49                 return stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json') ||
  50                         stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/ld+json');
  51         }
  52
  53         /**
  54          * Checks incoming message from the inbox
  55          *
  56          * @param $body
  57          * @param $header
  58          * @param integer $uid User ID
  59          */
  60         public static function processInbox($body, $header, $uid)
  61         {
  62                 $http_signer = HTTPSignature::getSigner($body, $header);
  63                 if (empty($http_signer)) {
  64                         Logger::log('Invalid HTTP signature, message will be discarded.', Logger::DEBUG);
  65                         return;
  66                 } else {
  67                         Logger::log('HTTP signature is signed by ' . $http_signer, Logger::DEBUG);
  68                 }
  69
  70                 $activity = json_decode($body, true);
  71
  72                 if (empty($activity)) {
  73                         Logger::log('Invalid body.', Logger::DEBUG);
  74                         return;
  75                 }
  76
  77                 $ldactivity = JsonLD::compact($activity);
  78
  79                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor');
  80
  81                 Logger::log('Message for user ' . $uid . ' is from actor ' . $actor, Logger::DEBUG);
  82
  83                 if (LDSignature::isSigned($activity)) {
  84                         $ld_signer = LDSignature::getSigner($activity);
  85                         if (empty($ld_signer)) {
  86                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
  87                         }
  88                         if (!empty($ld_signer && ($actor == $http_signer))) {
  89                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
  90                                 $trust_source = true;
  91                         } elseif (!empty($ld_signer)) {
  92                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
  93                                 $trust_source = true;
  94                         } elseif ($actor == $http_signer) {
  95                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
  96                                 $trust_source = true;
  97                         } else {
  98                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
  99                                 $trust_source = false;
 100                         }
 101                 } elseif ($actor == $http_signer) {
 102                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
 103                         $trust_source = true;
 104                 } else {
 105                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
 106                         $trust_source = false;
 107                 }
 108
 109                 self::processActivity($ldactivity, $body, $uid, $trust_source);
 110         }
 111
 112         /**
 113          * Fetches the object type for a given object id
 114          *
 115          * @param array   $activity
 116          * @param string  $object_id Object ID of the the provided object
 117          * @param integer $uid User ID
 118          *
 119          * @return string with object type
 120          */
 121         private static function fetchObjectType($activity, $object_id, $uid = 0)
 122         {
 123                 if (!empty($activity['as:object'])) {
 124                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 125                         if (!empty($object_type)) {
 126                                 return $object_type;
 127                         }
 128                 }
 129
 130                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 131                         // We just assume "note" since it doesn't make a difference for the further processing
 132                         return 'as:Note';
 133                 }
 134
 135                 $profile = APContact::getByURL($object_id);
 136                 if (!empty($profile['type'])) {
 137                         return 'as:' . $profile['type'];
 138                 }
 139
 140                 $data = ActivityPub::fetchContent($object_id, $uid);
 141                 if (!empty($data)) {
 142                         $object = JsonLD::compact($data);
 143                         $type = JsonLD::fetchElement($object, '@type');
 144                         if (!empty($type)) {
 145                                 return $type;
 146                         }
 147                 }
 148
 149                 return null;
 150         }
 151
 152         /**
 153          * Prepare the object array
 154          *
 155          * @param array $activity
 156          * @param integer $uid User ID
 157          * @param $trust_source
 158          *
 159          * @return array with object data
 160          */
 161         private static function prepareObjectData($activity, $uid, &$trust_source)
 162         {
 163                 $actor = JsonLD::fetchElement($activity, 'as:actor');
 164                 if (empty($actor)) {
 165                         Logger::log('Empty actor', Logger::DEBUG);
 166                         return [];
 167                 }
 168
 169                 $type = JsonLD::fetchElement($activity, '@type');
 170
 171                 // Fetch all receivers from to, cc, bto and bcc
 172                 $receivers = self::getReceivers($activity, $actor);
 173
 174                 // When it is a delivery to a personal inbox we add that user to the receivers
 175                 if (!empty($uid)) {
 176                         $additional = ['uid:' . $uid => $uid];
 177                         $receivers = array_merge($receivers, $additional);
 178                 } else {
 179                         // We possibly need some user to fetch private content,
 180                         // so we fetch the first out ot the list.
 181                         $uid = self::getFirstUserFromReceivers($receivers);
 182                 }
 183
 184                 Logger::log('Receivers: ' . $uid . ' - ' . json_encode($receivers), Logger::DEBUG);
 185
 186                 $object_id = JsonLD::fetchElement($activity, 'as:object');
 187                 if (empty($object_id)) {
 188                         Logger::log('No object found', Logger::DEBUG);
 189                         return [];
 190                 }
 191
 192                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
 193
 194                 // Fetch the content only on activities where this matters
 195                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 196                         if ($type == 'as:Announce') {
 197                                 $trust_source = false;
 198                         }
 199                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $uid);
 200                         if (empty($object_data)) {
 201                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
 202                                 return [];
 203                         }
 204                         // We had been able to retrieve the object data - so we can trust the source
 205                         $trust_source = true;
 206                 } elseif (in_array($type, ['as:Like', 'as:Dislike'])) {
 207                         // Create a mostly empty array out of the activity data (instead of the object).
 208                         // This way we later don't have to check for the existence of ech individual array element.
 209                         $object_data = self::processObject($activity);
 210                         $object_data['name'] = $type;
 211                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor');
 212                         $object_data['object_id'] = $object_id;
 213                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 214                 } else {
 215                         $object_data = [];
 216                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 217                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object');
 218                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor');
 219                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 220                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 221
 222                         // An Undo is done on the object of an object, so we need that type as well
 223                         if ($type == 'as:Undo') {
 224                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 225                         }
 226                 }
 227
 228                 $object_data = self::addActivityFields($object_data, $activity);
 229
 230                 if (empty($object_data['object_type'])) {
 231                         $object_data['object_type'] = $object_type;
 232                 }
 233
 234                 $object_data['type'] = $type;
 235                 $object_data['actor'] = $actor;
 236                 $object_data['item_receiver'] = $receivers;
 237                 $object_data['receiver'] = array_merge(defaults($object_data, 'receiver', []), $receivers);
 238
 239                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 240
 241                 return $object_data;
 242         }
 243
 244         /**
 245          * Fetches the first user id from the receiver array
 246          *
 247          * @param array $receivers Array with receivers
 248          * @return integer user id;
 249          */
 250         public static function getFirstUserFromReceivers($receivers)
 251         {
 252                 foreach ($receivers as $receiver) {
 253                         if (!empty($receiver)) {
 254                                 return $receiver;
 255                         }
 256                 }
 257                 return 0;
 258         }
 259
 260         /**
 261          * Store the unprocessed data into the conversation table
 262          * This has to be done outside the regular function,
 263          * since we store everything - not only item posts.
 264          *
 265          * @param array  $activity Array with activity data
 266          * @param string $body     The raw message
 267          */
 268         private static function storeConversation($activity, $body)
 269         {
 270                 if (empty($body) || empty($activity['id'])) {
 271                         return;
 272                 }
 273
 274                 $conversation = [
 275                         'protocol' => Conversation::PARCEL_ACTIVITYPUB,
 276                         'item-uri' => $activity['id'],
 277                         'reply-to-uri' => defaults($activity, 'reply-to-id', ''),
 278                         'conversation-href' => defaults($activity, 'context', ''),
 279                         'conversation-uri' => defaults($activity, 'conversation', ''),
 280                         'source' => $body,
 281                         'received' => DateTimeFormat::utcNow()];
 282
 283                 DBA::insert('conversation', $conversation, true);
 284         }
 285
 286         /**
 287          * Processes the activity object
 288          *
 289          * @param array   $activity     Array with activity data
 290          * @param string  $body
 291          * @param integer $uid          User ID
 292          * @param boolean $trust_source Do we trust the source?
 293          */
 294         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false)
 295         {
 296                 $type = JsonLD::fetchElement($activity, '@type');
 297                 if (!$type) {
 298                         Logger::log('Empty type', Logger::DEBUG);
 299                         return;
 300                 }
 301
 302                 if (!JsonLD::fetchElement($activity, 'as:object')) {
 303                         Logger::log('Empty object', Logger::DEBUG);
 304                         return;
 305                 }
 306
 307                 if (!JsonLD::fetchElement($activity, 'as:actor')) {
 308                         Logger::log('Empty actor', Logger::DEBUG);
 309                         return;
 310
 311                 }
 312
 313                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
 314                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
 315                         $actor = JsonLD::fetchElement($activity, 'as:actor');
 316                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo');
 317                         $trust_source = ($actor == $attributed_to);
 318                         if (!$trust_source) {
 319                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
 320                         }
 321                 }
 322
 323                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 324                 $object_data = self::prepareObjectData($activity, $uid, $trust_source);
 325                 if (empty($object_data)) {
 326                         Logger::log('No object data found', Logger::DEBUG);
 327                         return;
 328                 }
 329
 330                 if (!$trust_source) {
 331                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
 332                         return;
 333                 }
 334
 335                 self::storeConversation($object_data, $body);
 336
 337                 // Internal flag for thread completion. See Processor.php
 338                 if (!empty($activity['thread-completion'])) {
 339                         $object_data['thread-completion'] = $activity['thread-completion'];
 340                 }
 341
 342                 switch ($type) {
 343                         case 'as:Create':
 344                         case 'as:Announce':
 345                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 346                                         ActivityPub\Processor::createItem($object_data);
 347                                 }
 348                                 break;
 349
 350                         case 'as:Like':
 351                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 352                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_LIKE);
 353                                 }
 354                                 break;
 355
 356                         case 'as:Dislike':
 357                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 358                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_DISLIKE);
 359                                 }
 360                                 break;
 361
 362                         case 'as:TentativeAccept':
 363                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 364                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDMAYBE);
 365                                 }
 366                                 break;
 367
 368                         case 'as:Update':
 369                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 370                                         ActivityPub\Processor::updateItem($object_data);
 371                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 372                                         ActivityPub\Processor::updatePerson($object_data, $body);
 373                                 }
 374                                 break;
 375
 376                         case 'as:Delete':
 377                                 if ($object_data['object_type'] == 'as:Tombstone') {
 378                                         ActivityPub\Processor::deleteItem($object_data, $body);
 379                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 380                                         ActivityPub\Processor::deletePerson($object_data, $body);
 381                                 }
 382                                 break;
 383
 384                         case 'as:Follow':
 385                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 386                                         ActivityPub\Processor::followUser($object_data);
 387                                 }
 388                                 break;
 389
 390                         case 'as:Accept':
 391                                 if ($object_data['object_type'] == 'as:Follow') {
 392                                         ActivityPub\Processor::acceptFollowUser($object_data);
 393                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 394                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTEND);
 395                                 }
 396                                 break;
 397
 398                         case 'as:Reject':
 399                                 if ($object_data['object_type'] == 'as:Follow') {
 400                                         ActivityPub\Processor::rejectFollowUser($object_data);
 401                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 402                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDNO);
 403                                 }
 404                                 break;
 405
 406                         case 'as:Undo':
 407                                 if (($object_data['object_type'] == 'as:Follow') &&
 408                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 409                                         ActivityPub\Processor::undoFollowUser($object_data);
 410                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 411                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 412                                         ActivityPub\Processor::rejectFollowUser($object_data);
 413                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 414                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 415                                         ActivityPub\Processor::undoActivity($object_data);
 416                                 }
 417                                 break;
 418
 419                         default:
 420                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 421                                 break;
 422                 }
 423         }
 424
 425         /**
 426          * Fetch the receiver list from an activity array
 427          *
 428          * @param array $activity
 429          * @param string $actor
 430          * @param array $tags
 431          *
 432          * @return array with receivers (user id)
 433          */
 434         private static function getReceivers($activity, $actor, $tags = [])
 435         {
 436                 $receivers = [];
 437
 438                 // When it is an answer, we inherite the receivers from the parent
 439                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo');
 440                 if (!empty($replyto)) {
 441                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 442                         while ($parent = Item::fetch($parents)) {
 443                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 444                         }
 445                 }
 446
 447                 if (!empty($actor)) {
 448                         $profile = APContact::getByURL($actor);
 449                         $followers = defaults($profile, 'followers', '');
 450
 451                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 452                 } else {
 453                         Logger::log('Empty actor', Logger::DEBUG);
 454                         $followers = '';
 455                 }
 456
 457                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 458                         $receiver_list = JsonLD::fetchElementArray($activity, $element);
 459                         if (empty($receiver_list)) {
 460                                 continue;
 461                         }
 462
 463                         foreach ($receiver_list as $receiver) {
 464                                 if ($receiver == self::PUBLIC_COLLECTION) {
 465                                         $receivers['uid:0'] = 0;
 466                                 }
 467
 468                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 469                                         // This will most likely catch all OStatus connections to Mastodon
 470                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 471                                                 , 'archive' => false, 'pending' => false];
 472                                         $contacts = DBA::select('contact', ['uid'], $condition);
 473                                         while ($contact = DBA::fetch($contacts)) {
 474                                                 if ($contact['uid'] != 0) {
 475                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 476                                                 }
 477                                         }
 478                                         DBA::close($contacts);
 479                                 }
 480
 481                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 482                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 483                                         continue;
 484                                 }
 485
 486                                 // Fetching all directly addressed receivers
 487                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 488                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 489                                 if (!DBA::isResult($contact)) {
 490                                         continue;
 491                                 }
 492
 493                                 // Check if the potential receiver is following the actor
 494                                 // Exception: The receiver is targetted via "to" or this is a comment
 495                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::ACCOUNT_TYPE_COMMUNITY)) {
 496                                         $networks = [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::DIASPORA, Protocol::OSTATUS];
 497                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 498                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 499
 500                                         // Forum posts are only accepted from forum contacts
 501                                         if ($contact['contact-type'] == Contact::ACCOUNT_TYPE_COMMUNITY) {
 502                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 503                                         }
 504
 505                                         if (!DBA::exists('contact', $condition)) {
 506                                                 continue;
 507                                         }
 508                                 }
 509
 510                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 511                         }
 512                 }
 513
 514                 self::switchContacts($receivers, $actor);
 515
 516                 return $receivers;
 517         }
 518
 519         /**
 520          * Fetch the receiver list of a given actor
 521          *
 522          * @param string $actor
 523          * @param array $tags
 524          *
 525          * @return array with receivers (user id)
 526          */
 527         public static function getReceiverForActor($actor, $tags)
 528         {
 529                 $receivers = [];
 530                 $networks = [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::DIASPORA, Protocol::OSTATUS];
 531                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 532                         'network' => $networks, 'archive' => false, 'pending' => false];
 533                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 534                 while ($contact = DBA::fetch($contacts)) {
 535                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 536                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 537                         }
 538                 }
 539                 DBA::close($contacts);
 540                 return $receivers;
 541         }
 542
 543         /**
 544          * Tests if the contact is a valid receiver for this actor
 545          *
 546          * @param array $contact
 547          * @param string $actor
 548          * @param array $tags
 549          *
 550          * @return array with receivers (user id)
 551          */
 552         private static function isValidReceiverForActor($contact, $actor, $tags)
 553         {
 554                 // Public contacts are no valid receiver
 555                 if ($contact['uid'] == 0) {
 556                         return false;
 557                 }
 558
 559                 // Are we following the contact? Then this is a valid receiver
 560                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 561                         return true;
 562                 }
 563
 564                 // When the possible receiver isn't a community, then it is no valid receiver
 565                 $owner = User::getOwnerDataById($contact['uid']);
 566                 if (empty($owner) || ($owner['contact-type'] != Contact::ACCOUNT_TYPE_COMMUNITY)) {
 567                         return false;
 568                 }
 569
 570                 // Is the community account tagged?
 571                 foreach ($tags as $tag) {
 572                         if ($tag['type'] != 'Mention') {
 573                                 continue;
 574                         }
 575
 576                         if ($tag['href'] == $owner['url']) {
 577                                 return true;
 578                         }
 579                 }
 580
 581                 return false;
 582         }
 583
 584         /**
 585          * Switches existing contacts to ActivityPub
 586          *
 587          * @param integer $cid Contact ID
 588          * @param integer $uid User ID
 589          * @param string $url Profile URL
 590          */
 591         public static function switchContact($cid, $uid, $url)
 592         {
 593                 $profile = ActivityPub::probeProfile($url);
 594                 if (empty($profile)) {
 595                         return;
 596                 }
 597
 598                 Logger::log('Switch contact ' . $cid . ' (' . $profile['url'] . ') for user ' . $uid . ' to ActivityPub');
 599
 600                 $photo = defaults($profile, 'photo', null);
 601                 unset($profile['photo']);
 602                 unset($profile['baseurl']);
 603                 unset($profile['guid']);
 604
 605                 $profile['nurl'] = Strings::normaliseLink($profile['url']);
 606                 DBA::update('contact', $profile, ['id' => $cid]);
 607
 608                 Contact::updateAvatar($photo, $uid, $cid);
 609
 610                 // Send a new follow request to be sure that the connection still exists
 611                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND]])) {
 612                         ActivityPub\Transmitter::sendActivity('Follow', $profile['url'], $uid);
 613                         Logger::log('Send a new follow request to ' . $profile['url'] . ' for user ' . $uid, Logger::DEBUG);
 614                 }
 615         }
 616
 617         /**
 618          *
 619          *
 620          * @param $receivers
 621          * @param $actor
 622          */
 623         private static function switchContacts($receivers, $actor)
 624         {
 625                 if (empty($actor)) {
 626                         return;
 627                 }
 628
 629                 foreach ($receivers as $receiver) {
 630                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 631                         if (DBA::isResult($contact)) {
 632                                 self::switchContact($contact['id'], $receiver, $actor);
 633                         }
 634
 635                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 636                         if (DBA::isResult($contact)) {
 637                                 self::switchContact($contact['id'], $receiver, $actor);
 638                         }
 639                 }
 640         }
 641
 642         /**
 643          *
 644          *
 645          * @param $object_data
 646          * @param array $activity
 647          *
 648          * @return
 649          */
 650         private static function addActivityFields($object_data, $activity)
 651         {
 652                 if (!empty($activity['published']) && empty($object_data['published'])) {
 653                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 654                 }
 655
 656                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 657                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid');
 658                 }
 659
 660                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 661
 662                 return $object_data;
 663         }
 664
 665         /**
 666          * Fetches the object data from external ressources if needed
 667          *
 668          * @param string  $object_id    Object ID of the the provided object
 669          * @param array   $object       The provided object array
 670          * @param boolean $trust_source Do we trust the provided object?
 671          * @param integer $uid          User ID for the signature that we use to fetch data
 672          *
 673          * @return array with trusted and valid object data
 674          */
 675         private static function fetchObject($object_id, $object = [], $trust_source = false, $uid = 0)
 676         {
 677                 // By fetching the type we check if the object is complete.
 678                 $type = JsonLD::fetchElement($object, '@type');
 679
 680                 if (!$trust_source || empty($type)) {
 681                         $data = ActivityPub::fetchContent($object_id, $uid);
 682                         if (!empty($data)) {
 683                                 $object = JsonLD::compact($data);
 684                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 685                         } else {
 686                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 687
 688                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 689                                 if (!DBA::isResult($item)) {
 690                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 691                                         return false;
 692                                 }
 693                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 694                                 $data = ActivityPub\Transmitter::createNote($item);
 695                                 $object = JsonLD::compact($data);
 696                         }
 697                 } else {
 698                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 699                 }
 700
 701                 $type = JsonLD::fetchElement($object, '@type');
 702
 703                 if (empty($type)) {
 704                         Logger::log('Empty type', Logger::DEBUG);
 705                         return false;
 706                 }
 707
 708                 if (in_array($type, self::CONTENT_TYPES)) {
 709                         return self::processObject($object);
 710                 }
 711
 712                 if ($type == 'as:Announce') {
 713                         $object_id = JsonLD::fetchElement($object, 'object');
 714                         if (empty($object_id)) {
 715                                 return false;
 716                         }
 717                         return self::fetchObject($object_id, [], false, $uid);
 718                 }
 719
 720                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 721         }
 722
 723         /**
 724          * Convert tags from JSON-LD format into a simplified format
 725          *
 726          * @param array $tags Tags in JSON-LD format
 727          *
 728          * @return array with tags in a simplified format
 729          */
 730         private static function processTags($tags)
 731         {
 732                 $taglist = [];
 733
 734                 if (empty($tags)) {
 735                         return [];
 736                 }
 737
 738                 foreach ($tags as $tag) {
 739                         if (empty($tag)) {
 740                                 continue;
 741                         }
 742
 743                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 744                                 'href' => JsonLD::fetchElement($tag, 'as:href'),
 745                                 'name' => JsonLD::fetchElement($tag, 'as:name')];
 746
 747                         if (empty($element['type'])) {
 748                                 continue;
 749                         }
 750
 751                         $taglist[] = $element;
 752                 }
 753                 return $taglist;
 754         }
 755
 756         /**
 757          * Convert emojis from JSON-LD format into a simplified format
 758          *
 759          * @param array $tags Tags in JSON-LD format
 760          *
 761          * @return array with emojis in a simplified format
 762          */
 763         private static function processEmojis($emojis)
 764         {
 765                 $emojilist = [];
 766
 767                 if (empty($emojis)) {
 768                         return [];
 769                 }
 770
 771                 foreach ($emojis as $emoji) {
 772                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
 773                                 continue;
 774                         }
 775
 776                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url');
 777                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name'),
 778                                 'href' => $url];
 779
 780                         $emojilist[] = $element;
 781                 }
 782                 return $emojilist;
 783         }
 784
 785         /**
 786          * Convert attachments from JSON-LD format into a simplified format
 787          *
 788          * @param array $attachments Attachments in JSON-LD format
 789          *
 790          * @return array with attachmants in a simplified format
 791          */
 792         private static function processAttachments($attachments)
 793         {
 794                 $attachlist = [];
 795
 796                 if (empty($attachments)) {
 797                         return [];
 798                 }
 799
 800                 foreach ($attachments as $attachment) {
 801                         if (empty($attachment)) {
 802                                 continue;
 803                         }
 804
 805                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 806                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType'),
 807                                 'name' => JsonLD::fetchElement($attachment, 'as:name'),
 808                                 'url' => JsonLD::fetchElement($attachment, 'as:url')];
 809                 }
 810                 return $attachlist;
 811         }
 812
 813         /**
 814          * Fetches data from the object part of an activity
 815          *
 816          * @param array $object
 817          *
 818          * @return array
 819          */
 820         private static function processObject($object)
 821         {
 822                 if (!JsonLD::fetchElement($object, '@id')) {
 823                         return false;
 824                 }
 825
 826                 $object_data = [];
 827                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 828                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 829                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo');
 830
 831                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
 832                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
 833                         $object_data['reply-to-id'] = $object_data['id'];
 834                 }
 835
 836                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 837                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 838
 839                 if (empty($object_data['updated'])) {
 840                         $object_data['updated'] = $object_data['published'];
 841                 }
 842
 843                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 844                         $object_data['published'] = $object_data['updated'];
 845                 }
 846
 847                 $actor = JsonLD::fetchElement($object, 'as:attributedTo');
 848                 if (empty($actor)) {
 849                         $actor = JsonLD::fetchElement($object, 'as:actor');
 850                 }
 851
 852                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid');
 853                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment');
 854                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like');
 855                 $object_data['actor'] = $object_data['author'] = $actor;
 856                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context');
 857                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation');
 858                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 859                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name');
 860                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary');
 861                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content');
 862                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 863                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
 864                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
 865                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
 866                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
 867                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
 868                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
 869                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
 870                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
 871                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
 872                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji'));
 873                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
 874                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url');
 875
 876                 // Special treatment for Hubzilla links
 877                 if (is_array($object_data['alternate-url'])) {
 878                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href');
 879
 880                         if (!is_string($object_data['alternate-url'])) {
 881                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href');
 882                         }
 883                 }
 884
 885                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags']);
 886
 887                 // Common object data:
 888
 889                 // Unhandled
 890                 // @context, type, actor, signature, mediaType, duration, replies, icon
 891
 892                 // Also missing: (Defined in the standard, but currently unused)
 893                 // audience, preview, endTime, startTime, image
 894
 895                 // Data in Notes:
 896
 897                 // Unhandled
 898                 // contentMap, announcement_count, announcements, context_id, likes, like_count
 899                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
 900
 901                 // Data in video:
 902
 903                 // To-Do?
 904                 // category, licence, language, commentsEnabled
 905
 906                 // Unhandled
 907                 // views, waitTranscoding, state, support, subtitleLanguage
 908                 // likes, dislikes, shares, comments
 909
 910                 return $object_data;
 911         }
 912 }