src/Protocol/ActivityPub/Receiver.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2020, Friendica
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Protocol\ActivityPub;
  23
  24 use Friendica\Database\DBA;
  25 use Friendica\Content\Text\HTML;
  26 use Friendica\Content\Text\Markdown;
  27 use Friendica\Core\Logger;
  28 use Friendica\Core\Protocol;
  29 use Friendica\Model\Contact;
  30 use Friendica\Model\APContact;
  31 use Friendica\Model\Item;
  32 use Friendica\Model\User;
  33 use Friendica\Protocol\Activity;
  34 use Friendica\Protocol\ActivityPub;
  35 use Friendica\Util\DateTimeFormat;
  36 use Friendica\Util\HTTPSignature;
  37 use Friendica\Util\JsonLD;
  38 use Friendica\Util\LDSignature;
  39 use Friendica\Util\Strings;
  40
  41 /**
  42  * ActivityPub Receiver Protocol class
  43  *
  44  * To-Do:
  45  * @todo Undo Announce
  46  *
  47  * Check what this is meant to do:
  48  * - Add
  49  * - Block
  50  * - Flag
  51  * - Remove
  52  * - Undo Block
  53  */
  54 class Receiver
  55 {
  56         const PUBLIC_COLLECTION = 'as:Public';
  57         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  58         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event'];
  59         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  60
  61         /**
  62          * Checks if the web request is done for the AP protocol
  63          *
  64          * @return bool is it AP?
  65          */
  66         public static function isRequest()
  67         {
  68                 return stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/activity+json') ||
  69                         stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/ld+json');
  70         }
  71
  72         /**
  73          * Checks incoming message from the inbox
  74          *
  75          * @param         $body
  76          * @param         $header
  77          * @param integer $uid User ID
  78          * @throws \Exception
  79          */
  80         public static function processInbox($body, $header, $uid)
  81         {
  82                 $http_signer = HTTPSignature::getSigner($body, $header);
  83                 if (empty($http_signer)) {
  84                         Logger::warning('Invalid HTTP signature, message will be discarded.');
  85                         return;
  86                 } else {
  87                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
  88                 }
  89
  90                 $activity = json_decode($body, true);
  91
  92                 if (empty($activity)) {
  93                         Logger::warning('Invalid body.');
  94                         return;
  95                 }
  96
  97                 $ldactivity = JsonLD::compact($activity);
  98
  99                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor', '@id');
 100
 101                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
 102
 103                 if (LDSignature::isSigned($activity)) {
 104                         $ld_signer = LDSignature::getSigner($activity);
 105                         if (empty($ld_signer)) {
 106                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
 107                         }
 108                         if (!empty($ld_signer && ($actor == $http_signer))) {
 109                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
 110                                 $trust_source = true;
 111                         } elseif (!empty($ld_signer)) {
 112                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
 113                                 $trust_source = true;
 114                         } elseif ($actor == $http_signer) {
 115                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
 116                                 $trust_source = true;
 117                         } else {
 118                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
 119                                 $trust_source = false;
 120                         }
 121                 } elseif ($actor == $http_signer) {
 122                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
 123                         $trust_source = true;
 124                 } else {
 125                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
 126                         $trust_source = false;
 127                 }
 128
 129                 self::processActivity($ldactivity, $body, $uid, $trust_source);
 130         }
 131
 132         /**
 133          * Fetches the object type for a given object id
 134          *
 135          * @param array   $activity
 136          * @param string  $object_id Object ID of the the provided object
 137          * @param integer $uid       User ID
 138          *
 139          * @return string with object type
 140          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 141          * @throws \ImagickException
 142          */
 143         private static function fetchObjectType($activity, $object_id, $uid = 0)
 144         {
 145                 if (!empty($activity['as:object'])) {
 146                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 147                         if (!empty($object_type)) {
 148                                 return $object_type;
 149                         }
 150                 }
 151
 152                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 153                         // We just assume "note" since it doesn't make a difference for the further processing
 154                         return 'as:Note';
 155                 }
 156
 157                 $profile = APContact::getByURL($object_id);
 158                 if (!empty($profile['type'])) {
 159                         return 'as:' . $profile['type'];
 160                 }
 161
 162                 $data = ActivityPub::fetchContent($object_id, $uid);
 163                 if (!empty($data)) {
 164                         $object = JsonLD::compact($data);
 165                         $type = JsonLD::fetchElement($object, '@type');
 166                         if (!empty($type)) {
 167                                 return $type;
 168                         }
 169                 }
 170
 171                 return null;
 172         }
 173
 174         /**
 175          * Prepare the object array
 176          *
 177          * @param array   $activity
 178          * @param integer $uid User ID
 179          * @param         $trust_source
 180          *
 181          * @return array with object data
 182          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 183          * @throws \ImagickException
 184          */
 185         private static function prepareObjectData($activity, $uid, &$trust_source)
 186         {
 187                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 188                 if (empty($actor)) {
 189                         Logger::log('Empty actor', Logger::DEBUG);
 190                         return [];
 191                 }
 192
 193                 $type = JsonLD::fetchElement($activity, '@type');
 194
 195                 // Fetch all receivers from to, cc, bto and bcc
 196                 $receivers = self::getReceivers($activity, $actor);
 197
 198                 // When it is a delivery to a personal inbox we add that user to the receivers
 199                 if (!empty($uid)) {
 200                         $additional = ['uid:' . $uid => $uid];
 201                         $receivers = array_merge($receivers, $additional);
 202                 } else {
 203                         // We possibly need some user to fetch private content,
 204                         // so we fetch the first out ot the list.
 205                         $uid = self::getFirstUserFromReceivers($receivers);
 206                 }
 207
 208                 Logger::log('Receivers: ' . $uid . ' - ' . json_encode($receivers), Logger::DEBUG);
 209
 210                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 211                 if (empty($object_id)) {
 212                         Logger::log('No object found', Logger::DEBUG);
 213                         return [];
 214                 }
 215
 216                 if (!is_string($object_id)) {
 217                         Logger::info('Invalid object id', ['object' => $object_id]);
 218                         return [];
 219                 }
 220
 221                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
 222
 223                 // Fetch the content only on activities where this matters
 224                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 225                         if ($type == 'as:Announce') {
 226                                 $trust_source = false;
 227                         }
 228                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $uid);
 229                         if (empty($object_data)) {
 230                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
 231                                 return [];
 232                         }
 233                         $object_data['object_id'] = $object_id;
 234
 235                         // Test if it is an answer to a mail
 236                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 237                                 $object_data['directmessage'] = true;
 238                         } else {
 239                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 240                         }
 241
 242                         // We had been able to retrieve the object data - so we can trust the source
 243                         $trust_source = true;
 244                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 245                         // Create a mostly empty array out of the activity data (instead of the object).
 246                         // This way we later don't have to check for the existence of ech individual array element.
 247                         $object_data = self::processObject($activity);
 248                         $object_data['name'] = $type;
 249                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 250                         $object_data['object_id'] = $object_id;
 251                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 252                 } elseif (in_array($type, ['as:Add'])) {
 253                         $object_data = [];
 254                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 255                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 256                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 257                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 258                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 259                 } else {
 260                         $object_data = [];
 261                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 262                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 263                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 264                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 265                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 266
 267                         // An Undo is done on the object of an object, so we need that type as well
 268                         if ($type == 'as:Undo') {
 269                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 270                         }
 271                 }
 272
 273                 $object_data = self::addActivityFields($object_data, $activity);
 274
 275                 if (empty($object_data['object_type'])) {
 276                         $object_data['object_type'] = $object_type;
 277                 }
 278
 279                 $object_data['type'] = $type;
 280                 $object_data['actor'] = $actor;
 281                 $object_data['item_receiver'] = $receivers;
 282                 $object_data['receiver'] = array_merge($object_data['receiver'] ?? [], $receivers);
 283
 284                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 285
 286                 return $object_data;
 287         }
 288
 289         /**
 290          * Fetches the first user id from the receiver array
 291          *
 292          * @param array $receivers Array with receivers
 293          * @return integer user id;
 294          */
 295         public static function getFirstUserFromReceivers($receivers)
 296         {
 297                 foreach ($receivers as $receiver) {
 298                         if (!empty($receiver)) {
 299                                 return $receiver;
 300                         }
 301                 }
 302                 return 0;
 303         }
 304
 305         /**
 306          * Processes the activity object
 307          *
 308          * @param array   $activity     Array with activity data
 309          * @param string  $body
 310          * @param integer $uid          User ID
 311          * @param boolean $trust_source Do we trust the source?
 312          * @throws \Exception
 313          */
 314         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false)
 315         {
 316                 $type = JsonLD::fetchElement($activity, '@type');
 317                 if (!$type) {
 318                         Logger::log('Empty type', Logger::DEBUG);
 319                         return;
 320                 }
 321
 322                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 323                         Logger::log('Empty object', Logger::DEBUG);
 324                         return;
 325                 }
 326
 327                 if (!JsonLD::fetchElement($activity, 'as:actor', '@id')) {
 328                         Logger::log('Empty actor', Logger::DEBUG);
 329                         return;
 330
 331                 }
 332
 333                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
 334                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
 335                         $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 336                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 337                         $trust_source = ($actor == $attributed_to);
 338                         if (!$trust_source) {
 339                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
 340                         }
 341                 }
 342
 343                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 344                 $object_data = self::prepareObjectData($activity, $uid, $trust_source);
 345                 if (empty($object_data)) {
 346                         Logger::log('No object data found', Logger::DEBUG);
 347                         return;
 348                 }
 349
 350                 if (!$trust_source) {
 351                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
 352                         return;
 353                 }
 354
 355                 if (!empty($body)) {
 356                         $object_data['raw'] = $body;
 357                 }
 358
 359                 // Internal flag for thread completion. See Processor.php
 360                 if (!empty($activity['thread-completion'])) {
 361                         $object_data['thread-completion'] = $activity['thread-completion'];
 362                 }
 363
 364                 switch ($type) {
 365                         case 'as:Create':
 366                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 367                                         ActivityPub\Processor::createItem($object_data);
 368                                 }
 369                                 break;
 370
 371                         case 'as:Add':
 372                                 if ($object_data['object_type'] == 'as:tag') {
 373                                         ActivityPub\Processor::addTag($object_data);
 374                                 }
 375                                 break;
 376
 377                         case 'as:Announce':
 378                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 379                                         $profile = APContact::getByURL($object_data['actor']);
 380                                         // Reshared posts from persons appear as summary at the bottom
 381                                         // If this isn't set, then a single reshare appears on top. This is used for groups.
 382                                         $object_data['thread-completion'] = ($profile['type'] != 'Group');
 383
 384                                         ActivityPub\Processor::createItem($object_data);
 385
 386                                         // Add the bottom reshare information only for persons
 387                                         if ($profile['type'] != 'Group') {
 388                                                 $announce_object_data = self::processObject($activity);
 389                                                 $announce_object_data['name'] = $type;
 390                                                 $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 391                                                 $announce_object_data['object_id'] = $object_data['object_id'];
 392                                                 $announce_object_data['object_type'] = $object_data['object_type'];
 393
 394                                                 ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 395                                         }
 396                                 }
 397                                 break;
 398
 399                         case 'as:Like':
 400                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 401                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 402                                 }
 403                                 break;
 404
 405                         case 'as:Dislike':
 406                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 407                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 408                                 }
 409                                 break;
 410
 411                         case 'as:TentativeAccept':
 412                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 413                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 414                                 }
 415                                 break;
 416
 417                         case 'as:Update':
 418                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 419                                         ActivityPub\Processor::updateItem($object_data);
 420                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 421                                         ActivityPub\Processor::updatePerson($object_data);
 422                                 }
 423                                 break;
 424
 425                         case 'as:Delete':
 426                                 if ($object_data['object_type'] == 'as:Tombstone') {
 427                                         ActivityPub\Processor::deleteItem($object_data);
 428                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 429                                         ActivityPub\Processor::deletePerson($object_data);
 430                                 }
 431                                 break;
 432
 433                         case 'as:Follow':
 434                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 435                                         ActivityPub\Processor::followUser($object_data);
 436                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 437                                         $object_data['reply-to-id'] = $object_data['object_id'];
 438                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 439                                 }
 440                                 break;
 441
 442                         case 'as:Accept':
 443                                 if ($object_data['object_type'] == 'as:Follow') {
 444                                         ActivityPub\Processor::acceptFollowUser($object_data);
 445                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 446                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 447                                 }
 448                                 break;
 449
 450                         case 'as:Reject':
 451                                 if ($object_data['object_type'] == 'as:Follow') {
 452                                         ActivityPub\Processor::rejectFollowUser($object_data);
 453                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 454                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 455                                 }
 456                                 break;
 457
 458                         case 'as:Undo':
 459                                 if (($object_data['object_type'] == 'as:Follow') &&
 460                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 461                                         ActivityPub\Processor::undoFollowUser($object_data);
 462                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 463                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 464                                         ActivityPub\Processor::rejectFollowUser($object_data);
 465                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 466                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 467                                         ActivityPub\Processor::undoActivity($object_data);
 468                                 }
 469                                 break;
 470
 471                         default:
 472                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 473                                 break;
 474                 }
 475         }
 476
 477         /**
 478          * Fetch the receiver list from an activity array
 479          *
 480          * @param array   $activity
 481          * @param string  $actor
 482          * @param array   $tags
 483          * @param boolean $fetch_unlisted
 484          *
 485          * @return array with receivers (user id)
 486          * @throws \Exception
 487          */
 488         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 489         {
 490                 $receivers = [];
 491
 492                 // When it is an answer, we inherite the receivers from the parent
 493                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 494                 if (!empty($replyto)) {
 495                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 496                         $fixedReplyTo = Item::getURIByLink($replyto);
 497                         $replyto = $fixedReplyTo ?: $replyto;
 498
 499                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 500                         while ($parent = Item::fetch($parents)) {
 501                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 502                         }
 503                 }
 504
 505                 if (!empty($actor)) {
 506                         $profile = APContact::getByURL($actor);
 507                         $followers = $profile['followers'] ?? '';
 508
 509                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 510                 } else {
 511                         Logger::log('Empty actor', Logger::DEBUG);
 512                         $followers = '';
 513                 }
 514
 515                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 516                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 517                         if (empty($receiver_list)) {
 518                                 continue;
 519                         }
 520
 521                         foreach ($receiver_list as $receiver) {
 522                                 if ($receiver == self::PUBLIC_COLLECTION) {
 523                                         $receivers['uid:0'] = 0;
 524                                 }
 525
 526                                 // Add receiver "-1" for unlisted posts
 527                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 528                                         $receivers['uid:-1'] = -1;
 529                                 }
 530
 531                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 532                                         // This will most likely catch all OStatus connections to Mastodon
 533                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 534                                                 , 'archive' => false, 'pending' => false];
 535                                         $contacts = DBA::select('contact', ['uid'], $condition);
 536                                         while ($contact = DBA::fetch($contacts)) {
 537                                                 if ($contact['uid'] != 0) {
 538                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 539                                                 }
 540                                         }
 541                                         DBA::close($contacts);
 542                                 }
 543
 544                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 545                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 546                                         continue;
 547                                 }
 548
 549                                 // Fetching all directly addressed receivers
 550                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 551                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 552                                 if (!DBA::isResult($contact)) {
 553                                         continue;
 554                                 }
 555
 556                                 // Check if the potential receiver is following the actor
 557                                 // Exception: The receiver is targetted via "to" or this is a comment
 558                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 559                                         $networks = Protocol::FEDERATED;
 560                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 561                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 562
 563                                         // Forum posts are only accepted from forum contacts
 564                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 565                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 566                                         }
 567
 568                                         if (!DBA::exists('contact', $condition)) {
 569                                                 continue;
 570                                         }
 571                                 }
 572
 573                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 574                         }
 575                 }
 576
 577                 self::switchContacts($receivers, $actor);
 578
 579                 return $receivers;
 580         }
 581
 582         /**
 583          * Fetch the receiver list of a given actor
 584          *
 585          * @param string $actor
 586          * @param array  $tags
 587          *
 588          * @return array with receivers (user id)
 589          * @throws \Exception
 590          */
 591         public static function getReceiverForActor($actor, $tags)
 592         {
 593                 $receivers = [];
 594                 $networks = Protocol::FEDERATED;
 595                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 596                         'network' => $networks, 'archive' => false, 'pending' => false];
 597                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 598                 while ($contact = DBA::fetch($contacts)) {
 599                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 600                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 601                         }
 602                 }
 603                 DBA::close($contacts);
 604                 return $receivers;
 605         }
 606
 607         /**
 608          * Tests if the contact is a valid receiver for this actor
 609          *
 610          * @param array  $contact
 611          * @param string $actor
 612          * @param array  $tags
 613          *
 614          * @return bool with receivers (user id)
 615          * @throws \Exception
 616          */
 617         private static function isValidReceiverForActor($contact, $actor, $tags)
 618         {
 619                 // Public contacts are no valid receiver
 620                 if ($contact['uid'] == 0) {
 621                         return false;
 622                 }
 623
 624                 // Are we following the contact? Then this is a valid receiver
 625                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 626                         return true;
 627                 }
 628
 629                 // When the possible receiver isn't a community, then it is no valid receiver
 630                 $owner = User::getOwnerDataById($contact['uid']);
 631                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 632                         return false;
 633                 }
 634
 635                 // Is the community account tagged?
 636                 foreach ($tags as $tag) {
 637                         if ($tag['type'] != 'Mention') {
 638                                 continue;
 639                         }
 640
 641                         if ($tag['href'] == $owner['url']) {
 642                                 return true;
 643                         }
 644                 }
 645
 646                 return false;
 647         }
 648
 649         /**
 650          * Switches existing contacts to ActivityPub
 651          *
 652          * @param integer $cid Contact ID
 653          * @param integer $uid User ID
 654          * @param string  $url Profile URL
 655          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 656          * @throws \ImagickException
 657          */
 658         public static function switchContact($cid, $uid, $url)
 659         {
 660                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 661                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 662                         return;
 663                 }
 664
 665                 if (Contact::updateFromProbe($cid, '', true)) {
 666                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 667                 }
 668
 669                 // Send a new follow request to be sure that the connection still exists
 670                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 671                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 672                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 673                 }
 674         }
 675
 676         /**
 677          *
 678          *
 679          * @param $receivers
 680          * @param $actor
 681          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 682          * @throws \ImagickException
 683          */
 684         private static function switchContacts($receivers, $actor)
 685         {
 686                 if (empty($actor)) {
 687                         return;
 688                 }
 689
 690                 foreach ($receivers as $receiver) {
 691                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 692                         if (DBA::isResult($contact)) {
 693                                 self::switchContact($contact['id'], $receiver, $actor);
 694                         }
 695
 696                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 697                         if (DBA::isResult($contact)) {
 698                                 self::switchContact($contact['id'], $receiver, $actor);
 699                         }
 700                 }
 701         }
 702
 703         /**
 704          *
 705          *
 706          * @param       $object_data
 707          * @param array $activity
 708          *
 709          * @return mixed
 710          */
 711         private static function addActivityFields($object_data, $activity)
 712         {
 713                 if (!empty($activity['published']) && empty($object_data['published'])) {
 714                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 715                 }
 716
 717                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 718                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 719                 }
 720
 721                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 722                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 723
 724                 if (!empty($object_data['object_id'])) {
 725                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 726                         $objectId = Item::getURIByLink($object_data['object_id']);
 727                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
 728                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
 729                                 $object_data['object_id'] = $objectId;
 730                         }
 731                 }
 732
 733                 return $object_data;
 734         }
 735
 736         /**
 737          * Fetches the object data from external ressources if needed
 738          *
 739          * @param string  $object_id    Object ID of the the provided object
 740          * @param array   $object       The provided object array
 741          * @param boolean $trust_source Do we trust the provided object?
 742          * @param integer $uid          User ID for the signature that we use to fetch data
 743          *
 744          * @return array|false with trusted and valid object data
 745          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 746          * @throws \ImagickException
 747          */
 748         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
 749         {
 750                 // By fetching the type we check if the object is complete.
 751                 $type = JsonLD::fetchElement($object, '@type');
 752
 753                 if (!$trust_source || empty($type)) {
 754                         $data = ActivityPub::fetchContent($object_id, $uid);
 755                         if (!empty($data)) {
 756                                 $object = JsonLD::compact($data);
 757                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 758                         } else {
 759                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 760
 761                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 762                                 if (!DBA::isResult($item)) {
 763                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 764                                         return false;
 765                                 }
 766                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 767                                 $data = ActivityPub\Transmitter::createNote($item);
 768                                 $object = JsonLD::compact($data);
 769                         }
 770                 } else {
 771                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 772                 }
 773
 774                 $type = JsonLD::fetchElement($object, '@type');
 775
 776                 if (empty($type)) {
 777                         Logger::log('Empty type', Logger::DEBUG);
 778                         return false;
 779                 }
 780
 781                 if (in_array($type, self::CONTENT_TYPES)) {
 782                         return self::processObject($object);
 783                 }
 784
 785                 if ($type == 'as:Announce') {
 786                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
 787                         if (empty($object_id) || !is_string($object_id)) {
 788                                 return false;
 789                         }
 790                         return self::fetchObject($object_id, [], false, $uid);
 791                 }
 792
 793                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 794                 return false;
 795         }
 796
 797         /**
 798          * Convert tags from JSON-LD format into a simplified format
 799          *
 800          * @param array $tags Tags in JSON-LD format
 801          *
 802          * @return array with tags in a simplified format
 803          */
 804         private static function processTags($tags)
 805         {
 806                 $taglist = [];
 807
 808                 if (empty($tags)) {
 809                         return [];
 810                 }
 811
 812                 foreach ($tags as $tag) {
 813                         if (empty($tag)) {
 814                                 continue;
 815                         }
 816
 817                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 818                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
 819                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
 820
 821                         if (empty($element['type'])) {
 822                                 continue;
 823                         }
 824
 825                         $taglist[] = $element;
 826                 }
 827                 return $taglist;
 828         }
 829
 830         /**
 831          * Convert emojis from JSON-LD format into a simplified format
 832          *
 833          * @param $emojis
 834          * @return array with emojis in a simplified format
 835          */
 836         private static function processEmojis($emojis)
 837         {
 838                 $emojilist = [];
 839
 840                 if (empty($emojis)) {
 841                         return [];
 842                 }
 843
 844                 foreach ($emojis as $emoji) {
 845                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
 846                                 continue;
 847                         }
 848
 849                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
 850                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
 851                                 'href' => $url];
 852
 853                         $emojilist[] = $element;
 854                 }
 855                 return $emojilist;
 856         }
 857
 858         /**
 859          * Convert attachments from JSON-LD format into a simplified format
 860          *
 861          * @param array $attachments Attachments in JSON-LD format
 862          *
 863          * @return array with attachmants in a simplified format
 864          */
 865         private static function processAttachments($attachments)
 866         {
 867                 $attachlist = [];
 868
 869                 if (empty($attachments)) {
 870                         return [];
 871                 }
 872
 873                 foreach ($attachments as $attachment) {
 874                         if (empty($attachment)) {
 875                                 continue;
 876                         }
 877
 878                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 879                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
 880                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
 881                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')];
 882                 }
 883                 return $attachlist;
 884         }
 885
 886         /**
 887          * Fetch the original source or content with the "language" Markdown or HTML
 888          *
 889          * @param array $object
 890          * @param array $object_data
 891          *
 892          * @return array
 893          * @throws \Exception
 894          */
 895         private static function getSource($object, $object_data)
 896         {
 897                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 898                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 899                 if (!empty($object_data['source'])) {
 900                         return $object_data;
 901                 }
 902
 903                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
 904                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 905                 if (!empty($object_data['source'])) {
 906                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
 907                         return $object_data;
 908                 }
 909
 910                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
 911                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 912                 if (!empty($object_data['source'])) {
 913                         $object_data['source'] = HTML::toBBCode($object_data['source']);
 914                         return $object_data;
 915                 }
 916
 917                 return $object_data;
 918         }
 919
 920         /**
 921          * Fetches data from the object part of an activity
 922          *
 923          * @param array $object
 924          *
 925          * @return array
 926          * @throws \Exception
 927          */
 928         private static function processObject($object)
 929         {
 930                 if (!JsonLD::fetchElement($object, '@id')) {
 931                         return false;
 932                 }
 933
 934                 $object_data = [];
 935                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 936                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 937                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
 938
 939                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
 940                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
 941                         $object_data['reply-to-id'] = $object_data['id'];
 942                 } else {
 943                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 944                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
 945                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
 946                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
 947                                 $object_data['reply-to-id'] = $replyToId;
 948                         }
 949                 }
 950
 951                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 952                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 953
 954                 if (empty($object_data['updated'])) {
 955                         $object_data['updated'] = $object_data['published'];
 956                 }
 957
 958                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 959                         $object_data['published'] = $object_data['updated'];
 960                 }
 961
 962                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
 963                 if (empty($actor)) {
 964                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
 965                 }
 966
 967                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
 968                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
 969                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
 970                 $object_data['actor'] = $object_data['author'] = $actor;
 971                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
 972                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
 973                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 974                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
 975                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
 976                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
 977                 $object_data = self::getSource($object, $object_data);
 978                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
 979                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
 980                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
 981                 $object_data['location'] = JsonLD::fetchElement($object_data, 'location', '@value');
 982                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
 983                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
 984                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
 985                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
 986                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
 987                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
 988                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji'));
 989                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
 990                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
 991                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
 992
 993                 // Special treatment for Hubzilla links
 994                 if (is_array($object_data['alternate-url'])) {
 995                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
 996
 997                         if (!is_string($object_data['alternate-url'])) {
 998                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
 999                         }
1000                 }
1001
1002                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1003                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1004                 unset($object_data['receiver']['uid:-1']);
1005
1006                 // Common object data:
1007
1008                 // Unhandled
1009                 // @context, type, actor, signature, mediaType, duration, replies, icon
1010
1011                 // Also missing: (Defined in the standard, but currently unused)
1012                 // audience, preview, endTime, startTime, image
1013
1014                 // Data in Notes:
1015
1016                 // Unhandled
1017                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1018                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1019
1020                 // Data in video:
1021
1022                 // To-Do?
1023                 // category, licence, language, commentsEnabled
1024
1025                 // Unhandled
1026                 // views, waitTranscoding, state, support, subtitleLanguage
1027                 // likes, dislikes, shares, comments
1028
1029                 return $object_data;
1030         }
1031 }