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 "' . $type . '", so we quit now.', Logger::DEBUG);
 332                         return;
 333                 }
 334
 335                 // Only store content related stuff - and no announces, since they possibly overwrite the original content
 336                 if (in_array($object_data['object_type'], self::CONTENT_TYPES) && ($type != 'as:Announce')) {
 337                         self::storeConversation($object_data, $body);
 338                 }
 339
 340                 // Internal flag for thread completion. See Processor.php
 341                 if (!empty($activity['thread-completion'])) {
 342                         $object_data['thread-completion'] = $activity['thread-completion'];
 343                 }
 344
 345                 switch ($type) {
 346                         case 'as:Create':
 347                         case 'as:Announce':
 348                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 349                                         ActivityPub\Processor::createItem($object_data);
 350                                 }
 351                                 break;
 352
 353                         case 'as:Like':
 354                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 355                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_LIKE);
 356                                 }
 357                                 break;
 358
 359                         case 'as:Dislike':
 360                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 361                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_DISLIKE);
 362                                 }
 363                                 break;
 364
 365                         case 'as:TentativeAccept':
 366                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 367                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDMAYBE);
 368                                 }
 369                                 break;
 370
 371                         case 'as:Update':
 372                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 373                                         ActivityPub\Processor::updateItem($object_data);
 374                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 375                                         ActivityPub\Processor::updatePerson($object_data, $body);
 376                                 }
 377                                 break;
 378
 379                         case 'as:Delete':
 380                                 if ($object_data['object_type'] == 'as:Tombstone') {
 381                                         ActivityPub\Processor::deleteItem($object_data, $body);
 382                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 383                                         ActivityPub\Processor::deletePerson($object_data, $body);
 384                                 }
 385                                 break;
 386
 387                         case 'as:Follow':
 388                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 389                                         ActivityPub\Processor::followUser($object_data);
 390                                 }
 391                                 break;
 392
 393                         case 'as:Accept':
 394                                 if ($object_data['object_type'] == 'as:Follow') {
 395                                         ActivityPub\Processor::acceptFollowUser($object_data);
 396                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 397                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTEND);
 398                                 }
 399                                 break;
 400
 401                         case 'as:Reject':
 402                                 if ($object_data['object_type'] == 'as:Follow') {
 403                                         ActivityPub\Processor::rejectFollowUser($object_data);
 404                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 405                                         ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDNO);
 406                                 }
 407                                 break;
 408
 409                         case 'as:Undo':
 410                                 if (($object_data['object_type'] == 'as:Follow') &&
 411                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 412                                         ActivityPub\Processor::undoFollowUser($object_data);
 413                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 414                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 415                                         ActivityPub\Processor::rejectFollowUser($object_data);
 416                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 417                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 418                                         ActivityPub\Processor::undoActivity($object_data);
 419                                 }
 420                                 break;
 421
 422                         default:
 423                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 424                                 break;
 425                 }
 426         }
 427
 428         /**
 429          * Fetch the receiver list from an activity array
 430          *
 431          * @param array $activity
 432          * @param string $actor
 433          * @param array $tags
 434          *
 435          * @return array with receivers (user id)
 436          */
 437         private static function getReceivers($activity, $actor, $tags = [])
 438         {
 439                 $receivers = [];
 440
 441                 // When it is an answer, we inherite the receivers from the parent
 442                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo');
 443                 if (!empty($replyto)) {
 444                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 445                         while ($parent = Item::fetch($parents)) {
 446                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 447                         }
 448                 }
 449
 450                 if (!empty($actor)) {
 451                         $profile = APContact::getByURL($actor);
 452                         $followers = defaults($profile, 'followers', '');
 453
 454                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 455                 } else {
 456                         Logger::log('Empty actor', Logger::DEBUG);
 457                         $followers = '';
 458                 }
 459
 460                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 461                         $receiver_list = JsonLD::fetchElementArray($activity, $element);
 462                         if (empty($receiver_list)) {
 463                                 continue;
 464                         }
 465
 466                         foreach ($receiver_list as $receiver) {
 467                                 if ($receiver == self::PUBLIC_COLLECTION) {
 468                                         $receivers['uid:0'] = 0;
 469                                 }
 470
 471                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 472                                         // This will most likely catch all OStatus connections to Mastodon
 473                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 474                                                 , 'archive' => false, 'pending' => false];
 475                                         $contacts = DBA::select('contact', ['uid'], $condition);
 476                                         while ($contact = DBA::fetch($contacts)) {
 477                                                 if ($contact['uid'] != 0) {
 478                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 479                                                 }
 480                                         }
 481                                         DBA::close($contacts);
 482                                 }
 483
 484                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 485                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 486                                         continue;
 487                                 }
 488
 489                                 // Fetching all directly addressed receivers
 490                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 491                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 492                                 if (!DBA::isResult($contact)) {
 493                                         continue;
 494                                 }
 495
 496                                 // Check if the potential receiver is following the actor
 497                                 // Exception: The receiver is targetted via "to" or this is a comment
 498                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::ACCOUNT_TYPE_COMMUNITY)) {
 499                                         $networks = [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::DIASPORA, Protocol::OSTATUS];
 500                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 501                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 502
 503                                         // Forum posts are only accepted from forum contacts
 504                                         if ($contact['contact-type'] == Contact::ACCOUNT_TYPE_COMMUNITY) {
 505                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 506                                         }
 507
 508                                         if (!DBA::exists('contact', $condition)) {
 509                                                 continue;
 510                                         }
 511                                 }
 512
 513                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 514                         }
 515                 }
 516
 517                 self::switchContacts($receivers, $actor);
 518
 519                 return $receivers;
 520         }
 521
 522         /**
 523          * Fetch the receiver list of a given actor
 524          *
 525          * @param string $actor
 526          * @param array $tags
 527          *
 528          * @return array with receivers (user id)
 529          */
 530         public static function getReceiverForActor($actor, $tags)
 531         {
 532                 $receivers = [];
 533                 $networks = [Protocol::ACTIVITYPUB, Protocol::DFRN, Protocol::DIASPORA, Protocol::OSTATUS];
 534                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 535                         'network' => $networks, 'archive' => false, 'pending' => false];
 536                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 537                 while ($contact = DBA::fetch($contacts)) {
 538                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 539                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 540                         }
 541                 }
 542                 DBA::close($contacts);
 543                 return $receivers;
 544         }
 545
 546         /**
 547          * Tests if the contact is a valid receiver for this actor
 548          *
 549          * @param array $contact
 550          * @param string $actor
 551          * @param array $tags
 552          *
 553          * @return array with receivers (user id)
 554          */
 555         private static function isValidReceiverForActor($contact, $actor, $tags)
 556         {
 557                 // Public contacts are no valid receiver
 558                 if ($contact['uid'] == 0) {
 559                         return false;
 560                 }
 561
 562                 // Are we following the contact? Then this is a valid receiver
 563                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 564                         return true;
 565                 }
 566
 567                 // When the possible receiver isn't a community, then it is no valid receiver
 568                 $owner = User::getOwnerDataById($contact['uid']);
 569                 if (empty($owner) || ($owner['contact-type'] != Contact::ACCOUNT_TYPE_COMMUNITY)) {
 570                         return false;
 571                 }
 572
 573                 // Is the community account tagged?
 574                 foreach ($tags as $tag) {
 575                         if ($tag['type'] != 'Mention') {
 576                                 continue;
 577                         }
 578
 579                         if ($tag['href'] == $owner['url']) {
 580                                 return true;
 581                         }
 582                 }
 583
 584                 return false;
 585         }
 586
 587         /**
 588          * Switches existing contacts to ActivityPub
 589          *
 590          * @param integer $cid Contact ID
 591          * @param integer $uid User ID
 592          * @param string $url Profile URL
 593          */
 594         public static function switchContact($cid, $uid, $url)
 595         {
 596                 $profile = ActivityPub::probeProfile($url);
 597                 if (empty($profile)) {
 598                         return;
 599                 }
 600
 601                 Logger::log('Switch contact ' . $cid . ' (' . $profile['url'] . ') for user ' . $uid . ' to ActivityPub');
 602
 603                 $photo = defaults($profile, 'photo', null);
 604                 unset($profile['photo']);
 605                 unset($profile['baseurl']);
 606                 unset($profile['guid']);
 607
 608                 $profile['nurl'] = Strings::normaliseLink($profile['url']);
 609                 DBA::update('contact', $profile, ['id' => $cid]);
 610
 611                 Contact::updateAvatar($photo, $uid, $cid);
 612
 613                 // Send a new follow request to be sure that the connection still exists
 614                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND]])) {
 615                         ActivityPub\Transmitter::sendActivity('Follow', $profile['url'], $uid);
 616                         Logger::log('Send a new follow request to ' . $profile['url'] . ' for user ' . $uid, Logger::DEBUG);
 617                 }
 618         }
 619
 620         /**
 621          *
 622          *
 623          * @param $receivers
 624          * @param $actor
 625          */
 626         private static function switchContacts($receivers, $actor)
 627         {
 628                 if (empty($actor)) {
 629                         return;
 630                 }
 631
 632                 foreach ($receivers as $receiver) {
 633                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 634                         if (DBA::isResult($contact)) {
 635                                 self::switchContact($contact['id'], $receiver, $actor);
 636                         }
 637
 638                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 639                         if (DBA::isResult($contact)) {
 640                                 self::switchContact($contact['id'], $receiver, $actor);
 641                         }
 642                 }
 643         }
 644
 645         /**
 646          *
 647          *
 648          * @param $object_data
 649          * @param array $activity
 650          *
 651          * @return
 652          */
 653         private static function addActivityFields($object_data, $activity)
 654         {
 655                 if (!empty($activity['published']) && empty($object_data['published'])) {
 656                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 657                 }
 658
 659                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 660                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid');
 661                 }
 662
 663                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 664
 665                 return $object_data;
 666         }
 667
 668         /**
 669          * Fetches the object data from external ressources if needed
 670          *
 671          * @param string  $object_id    Object ID of the the provided object
 672          * @param array   $object       The provided object array
 673          * @param boolean $trust_source Do we trust the provided object?
 674          * @param integer $uid          User ID for the signature that we use to fetch data
 675          *
 676          * @return array with trusted and valid object data
 677          */
 678         private static function fetchObject($object_id, $object = [], $trust_source = false, $uid = 0)
 679         {
 680                 // By fetching the type we check if the object is complete.
 681                 $type = JsonLD::fetchElement($object, '@type');
 682
 683                 if (!$trust_source || empty($type)) {
 684                         $data = ActivityPub::fetchContent($object_id, $uid);
 685                         if (!empty($data)) {
 686                                 $object = JsonLD::compact($data);
 687                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 688                         } else {
 689                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 690
 691                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 692                                 if (!DBA::isResult($item)) {
 693                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 694                                         return false;
 695                                 }
 696                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 697                                 $data = ActivityPub\Transmitter::createNote($item);
 698                                 $object = JsonLD::compact($data);
 699                         }
 700                 } else {
 701                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 702                 }
 703
 704                 $type = JsonLD::fetchElement($object, '@type');
 705
 706                 if (empty($type)) {
 707                         Logger::log('Empty type', Logger::DEBUG);
 708                         return false;
 709                 }
 710
 711                 if (in_array($type, self::CONTENT_TYPES)) {
 712                         return self::processObject($object);
 713                 }
 714
 715                 if ($type == 'as:Announce') {
 716                         $object_id = JsonLD::fetchElement($object, 'object');
 717                         if (empty($object_id)) {
 718                                 return false;
 719                         }
 720                         return self::fetchObject($object_id, [], false, $uid);
 721                 }
 722
 723                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 724         }
 725
 726         /**
 727          * Convert tags from JSON-LD format into a simplified format
 728          *
 729          * @param array $tags Tags in JSON-LD format
 730          *
 731          * @return array with tags in a simplified format
 732          */
 733         private static function processTags($tags)
 734         {
 735                 $taglist = [];
 736
 737                 if (empty($tags)) {
 738                         return [];
 739                 }
 740
 741                 foreach ($tags as $tag) {
 742                         if (empty($tag)) {
 743                                 continue;
 744                         }
 745
 746                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 747                                 'href' => JsonLD::fetchElement($tag, 'as:href'),
 748                                 'name' => JsonLD::fetchElement($tag, 'as:name')];
 749
 750                         if (empty($element['type'])) {
 751                                 continue;
 752                         }
 753
 754                         $taglist[] = $element;
 755                 }
 756                 return $taglist;
 757         }
 758
 759         /**
 760          * Convert emojis from JSON-LD format into a simplified format
 761          *
 762          * @param array $tags Tags in JSON-LD format
 763          *
 764          * @return array with emojis in a simplified format
 765          */
 766         private static function processEmojis($emojis)
 767         {
 768                 $emojilist = [];
 769
 770                 if (empty($emojis)) {
 771                         return [];
 772                 }
 773
 774                 foreach ($emojis as $emoji) {
 775                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
 776                                 continue;
 777                         }
 778
 779                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url');
 780                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name'),
 781                                 'href' => $url];
 782
 783                         $emojilist[] = $element;
 784                 }
 785                 return $emojilist;
 786         }
 787
 788         /**
 789          * Convert attachments from JSON-LD format into a simplified format
 790          *
 791          * @param array $attachments Attachments in JSON-LD format
 792          *
 793          * @return array with attachmants in a simplified format
 794          */
 795         private static function processAttachments($attachments)
 796         {
 797                 $attachlist = [];
 798
 799                 if (empty($attachments)) {
 800                         return [];
 801                 }
 802
 803                 foreach ($attachments as $attachment) {
 804                         if (empty($attachment)) {
 805                                 continue;
 806                         }
 807
 808                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 809                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType'),
 810                                 'name' => JsonLD::fetchElement($attachment, 'as:name'),
 811                                 'url' => JsonLD::fetchElement($attachment, 'as:url')];
 812                 }
 813                 return $attachlist;
 814         }
 815
 816         /**
 817          * Fetches data from the object part of an activity
 818          *
 819          * @param array $object
 820          *
 821          * @return array
 822          */
 823         private static function processObject($object)
 824         {
 825                 if (!JsonLD::fetchElement($object, '@id')) {
 826                         return false;
 827                 }
 828
 829                 $object_data = [];
 830                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 831                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 832                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo');
 833
 834                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
 835                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
 836                         $object_data['reply-to-id'] = $object_data['id'];
 837                 }
 838
 839                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 840                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 841
 842                 if (empty($object_data['updated'])) {
 843                         $object_data['updated'] = $object_data['published'];
 844                 }
 845
 846                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 847                         $object_data['published'] = $object_data['updated'];
 848                 }
 849
 850                 $actor = JsonLD::fetchElement($object, 'as:attributedTo');
 851                 if (empty($actor)) {
 852                         $actor = JsonLD::fetchElement($object, 'as:actor');
 853                 }
 854
 855                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid');
 856                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment');
 857                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like');
 858                 $object_data['actor'] = $object_data['author'] = $actor;
 859                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context');
 860                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation');
 861                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 862                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name');
 863                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary');
 864                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content');
 865                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 866                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
 867                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
 868                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
 869                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
 870                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
 871                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
 872                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
 873                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
 874                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
 875                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji'));
 876                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
 877                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url');
 878
 879                 // Special treatment for Hubzilla links
 880                 if (is_array($object_data['alternate-url'])) {
 881                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href');
 882
 883                         if (!is_string($object_data['alternate-url'])) {
 884                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href');
 885                         }
 886                 }
 887
 888                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags']);
 889
 890                 // Common object data:
 891
 892                 // Unhandled
 893                 // @context, type, actor, signature, mediaType, duration, replies, icon
 894
 895                 // Also missing: (Defined in the standard, but currently unused)
 896                 // audience, preview, endTime, startTime, image
 897
 898                 // Data in Notes:
 899
 900                 // Unhandled
 901                 // contentMap, announcement_count, announcements, context_id, likes, like_count
 902                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
 903
 904                 // Data in video:
 905
 906                 // To-Do?
 907                 // category, licence, language, commentsEnabled
 908
 909                 // Unhandled
 910                 // views, waitTranscoding, state, support, subtitleLanguage
 911                 // likes, dislikes, shares, comments
 912
 913                 return $object_data;
 914         }
 915 }