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, true);
 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, $push, &$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                                 $push = false;
 228                         }
 229                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $uid);
 230                         if (empty($object_data)) {
 231                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
 232                                 return [];
 233                         }
 234
 235                         $object_data['object_id'] = $object_id;
 236                         $object_data['push'] = $push;
 237
 238                         // Test if it is an answer to a mail
 239                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 240                                 $object_data['directmessage'] = true;
 241                         } else {
 242                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 243                         }
 244
 245                         // We had been able to retrieve the object data - so we can trust the source
 246                         $trust_source = true;
 247                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 248                         // Create a mostly empty array out of the activity data (instead of the object).
 249                         // This way we later don't have to check for the existence of ech individual array element.
 250                         $object_data = self::processObject($activity);
 251                         $object_data['name'] = $type;
 252                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 253                         $object_data['object_id'] = $object_id;
 254                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 255                 } elseif (in_array($type, ['as:Add'])) {
 256                         $object_data = [];
 257                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 258                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 259                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 260                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 261                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 262                 } else {
 263                         $object_data = [];
 264                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 265                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 266                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 267                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 268                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 269
 270                         // An Undo is done on the object of an object, so we need that type as well
 271                         if ($type == 'as:Undo') {
 272                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 273                         }
 274                 }
 275
 276                 $object_data = self::addActivityFields($object_data, $activity);
 277
 278                 if (empty($object_data['object_type'])) {
 279                         $object_data['object_type'] = $object_type;
 280                 }
 281
 282                 $object_data['type'] = $type;
 283                 $object_data['actor'] = $actor;
 284                 $object_data['item_receiver'] = $receivers;
 285                 $object_data['receiver'] = array_merge($object_data['receiver'] ?? [], $receivers);
 286
 287                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 288
 289                 return $object_data;
 290         }
 291
 292         /**
 293          * Fetches the first user id from the receiver array
 294          *
 295          * @param array $receivers Array with receivers
 296          * @return integer user id;
 297          */
 298         public static function getFirstUserFromReceivers($receivers)
 299         {
 300                 foreach ($receivers as $receiver) {
 301                         if (!empty($receiver)) {
 302                                 return $receiver;
 303                         }
 304                 }
 305                 return 0;
 306         }
 307
 308         /**
 309          * Processes the activity object
 310          *
 311          * @param array   $activity     Array with activity data
 312          * @param string  $body
 313          * @param integer $uid          User ID
 314          * @param boolean $trust_source Do we trust the source?
 315          * @throws \Exception
 316          */
 317         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false, $push = false)
 318         {
 319                 $type = JsonLD::fetchElement($activity, '@type');
 320                 if (!$type) {
 321                         Logger::log('Empty type', Logger::DEBUG);
 322                         return;
 323                 }
 324
 325                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 326                         Logger::log('Empty object', Logger::DEBUG);
 327                         return;
 328                 }
 329
 330                 if (!JsonLD::fetchElement($activity, 'as:actor', '@id')) {
 331                         Logger::log('Empty actor', Logger::DEBUG);
 332                         return;
 333
 334                 }
 335
 336                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
 337                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
 338                         $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 339                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 340                         $trust_source = ($actor == $attributed_to);
 341                         if (!$trust_source) {
 342                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
 343                         }
 344                 }
 345
 346                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 347                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
 348                 if (empty($object_data)) {
 349                         Logger::log('No object data found', Logger::DEBUG);
 350                         return;
 351                 }
 352
 353                 if (!$trust_source) {
 354                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
 355                         return;
 356                 }
 357
 358                 if (!empty($body)) {
 359                         $object_data['raw'] = $body;
 360                 }
 361
 362                 // Internal flag for thread completion. See Processor.php
 363                 if (!empty($activity['thread-completion'])) {
 364                         $object_data['thread-completion'] = $activity['thread-completion'];
 365                 }
 366
 367                 switch ($type) {
 368                         case 'as:Create':
 369                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 370                                         ActivityPub\Processor::createItem($object_data);
 371                                 }
 372                                 break;
 373
 374                         case 'as:Add':
 375                                 if ($object_data['object_type'] == 'as:tag') {
 376                                         ActivityPub\Processor::addTag($object_data);
 377                                 }
 378                                 break;
 379
 380                         case 'as:Announce':
 381                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 382                                         $profile = APContact::getByURL($object_data['actor']);
 383                                         // Reshared posts from persons appear as summary at the bottom
 384                                         // If this isn't set, then a single reshare appears on top. This is used for groups.
 385                                         $object_data['thread-completion'] = ($profile['type'] != 'Group');
 386
 387                                         ActivityPub\Processor::createItem($object_data);
 388
 389                                         // Add the bottom reshare information only for persons
 390                                         if ($profile['type'] != 'Group') {
 391                                                 $announce_object_data = self::processObject($activity);
 392                                                 $announce_object_data['name'] = $type;
 393                                                 $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 394                                                 $announce_object_data['object_id'] = $object_data['object_id'];
 395                                                 $announce_object_data['object_type'] = $object_data['object_type'];
 396
 397                                                 ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 398                                         }
 399                                 }
 400                                 break;
 401
 402                         case 'as:Like':
 403                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 404                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 405                                 }
 406                                 break;
 407
 408                         case 'as:Dislike':
 409                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 410                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 411                                 }
 412                                 break;
 413
 414                         case 'as:TentativeAccept':
 415                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 416                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 417                                 }
 418                                 break;
 419
 420                         case 'as:Update':
 421                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 422                                         ActivityPub\Processor::updateItem($object_data);
 423                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 424                                         ActivityPub\Processor::updatePerson($object_data);
 425                                 }
 426                                 break;
 427
 428                         case 'as:Delete':
 429                                 if ($object_data['object_type'] == 'as:Tombstone') {
 430                                         ActivityPub\Processor::deleteItem($object_data);
 431                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 432                                         ActivityPub\Processor::deletePerson($object_data);
 433                                 }
 434                                 break;
 435
 436                         case 'as:Follow':
 437                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 438                                         ActivityPub\Processor::followUser($object_data);
 439                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 440                                         $object_data['reply-to-id'] = $object_data['object_id'];
 441                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 442                                 }
 443                                 break;
 444
 445                         case 'as:Accept':
 446                                 if ($object_data['object_type'] == 'as:Follow') {
 447                                         ActivityPub\Processor::acceptFollowUser($object_data);
 448                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 449                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 450                                 }
 451                                 break;
 452
 453                         case 'as:Reject':
 454                                 if ($object_data['object_type'] == 'as:Follow') {
 455                                         ActivityPub\Processor::rejectFollowUser($object_data);
 456                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 457                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 458                                 }
 459                                 break;
 460
 461                         case 'as:Undo':
 462                                 if (($object_data['object_type'] == 'as:Follow') &&
 463                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 464                                         ActivityPub\Processor::undoFollowUser($object_data);
 465                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 466                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 467                                         ActivityPub\Processor::rejectFollowUser($object_data);
 468                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 469                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 470                                         ActivityPub\Processor::undoActivity($object_data);
 471                                 }
 472                                 break;
 473
 474                         default:
 475                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 476                                 break;
 477                 }
 478         }
 479
 480         /**
 481          * Fetch the receiver list from an activity array
 482          *
 483          * @param array   $activity
 484          * @param string  $actor
 485          * @param array   $tags
 486          * @param boolean $fetch_unlisted
 487          *
 488          * @return array with receivers (user id)
 489          * @throws \Exception
 490          */
 491         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 492         {
 493                 $receivers = [];
 494
 495                 // When it is an answer, we inherite the receivers from the parent
 496                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 497                 if (!empty($replyto)) {
 498                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 499                         $fixedReplyTo = Item::getURIByLink($replyto);
 500                         $replyto = $fixedReplyTo ?: $replyto;
 501
 502                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 503                         while ($parent = Item::fetch($parents)) {
 504                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 505                         }
 506                 }
 507
 508                 if (!empty($actor)) {
 509                         $profile = APContact::getByURL($actor);
 510                         $followers = $profile['followers'] ?? '';
 511
 512                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 513                 } else {
 514                         Logger::log('Empty actor', Logger::DEBUG);
 515                         $followers = '';
 516                 }
 517
 518                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 519                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 520                         if (empty($receiver_list)) {
 521                                 continue;
 522                         }
 523
 524                         foreach ($receiver_list as $receiver) {
 525                                 if ($receiver == self::PUBLIC_COLLECTION) {
 526                                         $receivers['uid:0'] = 0;
 527                                 }
 528
 529                                 // Add receiver "-1" for unlisted posts
 530                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 531                                         $receivers['uid:-1'] = -1;
 532                                 }
 533
 534                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 535                                         // This will most likely catch all OStatus connections to Mastodon
 536                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 537                                                 , 'archive' => false, 'pending' => false];
 538                                         $contacts = DBA::select('contact', ['uid'], $condition);
 539                                         while ($contact = DBA::fetch($contacts)) {
 540                                                 if ($contact['uid'] != 0) {
 541                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 542                                                 }
 543                                         }
 544                                         DBA::close($contacts);
 545                                 }
 546
 547                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 548                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 549                                         continue;
 550                                 }
 551
 552                                 // Fetching all directly addressed receivers
 553                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 554                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 555                                 if (!DBA::isResult($contact)) {
 556                                         continue;
 557                                 }
 558
 559                                 // Check if the potential receiver is following the actor
 560                                 // Exception: The receiver is targetted via "to" or this is a comment
 561                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 562                                         $networks = Protocol::FEDERATED;
 563                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 564                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 565
 566                                         // Forum posts are only accepted from forum contacts
 567                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 568                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 569                                         }
 570
 571                                         if (!DBA::exists('contact', $condition)) {
 572                                                 continue;
 573                                         }
 574                                 }
 575
 576                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 577                         }
 578                 }
 579
 580                 self::switchContacts($receivers, $actor);
 581
 582                 return $receivers;
 583         }
 584
 585         /**
 586          * Fetch the receiver list of a given actor
 587          *
 588          * @param string $actor
 589          * @param array  $tags
 590          *
 591          * @return array with receivers (user id)
 592          * @throws \Exception
 593          */
 594         public static function getReceiverForActor($actor, $tags)
 595         {
 596                 $receivers = [];
 597                 $networks = Protocol::FEDERATED;
 598                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 599                         'network' => $networks, 'archive' => false, 'pending' => false];
 600                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 601                 while ($contact = DBA::fetch($contacts)) {
 602                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 603                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 604                         }
 605                 }
 606                 DBA::close($contacts);
 607                 return $receivers;
 608         }
 609
 610         /**
 611          * Tests if the contact is a valid receiver for this actor
 612          *
 613          * @param array  $contact
 614          * @param string $actor
 615          * @param array  $tags
 616          *
 617          * @return bool with receivers (user id)
 618          * @throws \Exception
 619          */
 620         private static function isValidReceiverForActor($contact, $actor, $tags)
 621         {
 622                 // Public contacts are no valid receiver
 623                 if ($contact['uid'] == 0) {
 624                         return false;
 625                 }
 626
 627                 // Are we following the contact? Then this is a valid receiver
 628                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 629                         return true;
 630                 }
 631
 632                 // When the possible receiver isn't a community, then it is no valid receiver
 633                 $owner = User::getOwnerDataById($contact['uid']);
 634                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 635                         return false;
 636                 }
 637
 638                 // Is the community account tagged?
 639                 foreach ($tags as $tag) {
 640                         if ($tag['type'] != 'Mention') {
 641                                 continue;
 642                         }
 643
 644                         if ($tag['href'] == $owner['url']) {
 645                                 return true;
 646                         }
 647                 }
 648
 649                 return false;
 650         }
 651
 652         /**
 653          * Switches existing contacts to ActivityPub
 654          *
 655          * @param integer $cid Contact ID
 656          * @param integer $uid User ID
 657          * @param string  $url Profile URL
 658          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 659          * @throws \ImagickException
 660          */
 661         public static function switchContact($cid, $uid, $url)
 662         {
 663                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 664                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 665                         return;
 666                 }
 667
 668                 if (Contact::updateFromProbe($cid, '', true)) {
 669                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 670                 }
 671
 672                 // Send a new follow request to be sure that the connection still exists
 673                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 674                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 675                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 676                 }
 677         }
 678
 679         /**
 680          *
 681          *
 682          * @param $receivers
 683          * @param $actor
 684          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 685          * @throws \ImagickException
 686          */
 687         private static function switchContacts($receivers, $actor)
 688         {
 689                 if (empty($actor)) {
 690                         return;
 691                 }
 692
 693                 foreach ($receivers as $receiver) {
 694                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 695                         if (DBA::isResult($contact)) {
 696                                 self::switchContact($contact['id'], $receiver, $actor);
 697                         }
 698
 699                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 700                         if (DBA::isResult($contact)) {
 701                                 self::switchContact($contact['id'], $receiver, $actor);
 702                         }
 703                 }
 704         }
 705
 706         /**
 707          *
 708          *
 709          * @param       $object_data
 710          * @param array $activity
 711          *
 712          * @return mixed
 713          */
 714         private static function addActivityFields($object_data, $activity)
 715         {
 716                 if (!empty($activity['published']) && empty($object_data['published'])) {
 717                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 718                 }
 719
 720                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 721                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 722                 }
 723
 724                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 725                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 726
 727                 if (!empty($object_data['object_id'])) {
 728                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 729                         $objectId = Item::getURIByLink($object_data['object_id']);
 730                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
 731                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
 732                                 $object_data['object_id'] = $objectId;
 733                         }
 734                 }
 735
 736                 return $object_data;
 737         }
 738
 739         /**
 740          * Fetches the object data from external ressources if needed
 741          *
 742          * @param string  $object_id    Object ID of the the provided object
 743          * @param array   $object       The provided object array
 744          * @param boolean $trust_source Do we trust the provided object?
 745          * @param integer $uid          User ID for the signature that we use to fetch data
 746          *
 747          * @return array|false with trusted and valid object data
 748          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 749          * @throws \ImagickException
 750          */
 751         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
 752         {
 753                 // By fetching the type we check if the object is complete.
 754                 $type = JsonLD::fetchElement($object, '@type');
 755
 756                 if (!$trust_source || empty($type)) {
 757                         $data = ActivityPub::fetchContent($object_id, $uid);
 758                         if (!empty($data)) {
 759                                 $object = JsonLD::compact($data);
 760                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 761                         } else {
 762                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 763
 764                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 765                                 if (!DBA::isResult($item)) {
 766                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 767                                         return false;
 768                                 }
 769                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 770                                 $data = ActivityPub\Transmitter::createNote($item);
 771                                 $object = JsonLD::compact($data);
 772                         }
 773                 } else {
 774                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 775                 }
 776
 777                 $type = JsonLD::fetchElement($object, '@type');
 778
 779                 if (empty($type)) {
 780                         Logger::log('Empty type', Logger::DEBUG);
 781                         return false;
 782                 }
 783
 784                 if (in_array($type, self::CONTENT_TYPES)) {
 785                         return self::processObject($object);
 786                 }
 787
 788                 if ($type == 'as:Announce') {
 789                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
 790                         if (empty($object_id) || !is_string($object_id)) {
 791                                 return false;
 792                         }
 793                         return self::fetchObject($object_id, [], false, $uid);
 794                 }
 795
 796                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 797                 return false;
 798         }
 799
 800         /**
 801          * Convert tags from JSON-LD format into a simplified format
 802          *
 803          * @param array $tags Tags in JSON-LD format
 804          *
 805          * @return array with tags in a simplified format
 806          */
 807         private static function processTags($tags)
 808         {
 809                 $taglist = [];
 810
 811                 if (empty($tags)) {
 812                         return [];
 813                 }
 814
 815                 foreach ($tags as $tag) {
 816                         if (empty($tag)) {
 817                                 continue;
 818                         }
 819
 820                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 821                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
 822                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
 823
 824                         if (empty($element['type'])) {
 825                                 continue;
 826                         }
 827
 828                         $taglist[] = $element;
 829                 }
 830                 return $taglist;
 831         }
 832
 833         /**
 834          * Convert emojis from JSON-LD format into a simplified format
 835          *
 836          * @param $emojis
 837          * @return array with emojis in a simplified format
 838          */
 839         private static function processEmojis($emojis)
 840         {
 841                 $emojilist = [];
 842
 843                 if (empty($emojis)) {
 844                         return [];
 845                 }
 846
 847                 foreach ($emojis as $emoji) {
 848                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
 849                                 continue;
 850                         }
 851
 852                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
 853                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
 854                                 'href' => $url];
 855
 856                         $emojilist[] = $element;
 857                 }
 858                 return $emojilist;
 859         }
 860
 861         /**
 862          * Convert attachments from JSON-LD format into a simplified format
 863          *
 864          * @param array $attachments Attachments in JSON-LD format
 865          *
 866          * @return array with attachmants in a simplified format
 867          */
 868         private static function processAttachments($attachments)
 869         {
 870                 $attachlist = [];
 871
 872                 if (empty($attachments)) {
 873                         return [];
 874                 }
 875
 876                 foreach ($attachments as $attachment) {
 877                         if (empty($attachment)) {
 878                                 continue;
 879                         }
 880
 881                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 882                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
 883                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
 884                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')];
 885                 }
 886                 return $attachlist;
 887         }
 888
 889         /**
 890          * Fetch the original source or content with the "language" Markdown or HTML
 891          *
 892          * @param array $object
 893          * @param array $object_data
 894          *
 895          * @return array
 896          * @throws \Exception
 897          */
 898         private static function getSource($object, $object_data)
 899         {
 900                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 901                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 902                 if (!empty($object_data['source'])) {
 903                         return $object_data;
 904                 }
 905
 906                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
 907                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 908                 if (!empty($object_data['source'])) {
 909                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
 910                         return $object_data;
 911                 }
 912
 913                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
 914                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 915                 if (!empty($object_data['source'])) {
 916                         $object_data['source'] = HTML::toBBCode($object_data['source']);
 917                         return $object_data;
 918                 }
 919
 920                 return $object_data;
 921         }
 922
 923         /**
 924          * Fetches data from the object part of an activity
 925          *
 926          * @param array $object
 927          *
 928          * @return array
 929          * @throws \Exception
 930          */
 931         private static function processObject($object)
 932         {
 933                 if (!JsonLD::fetchElement($object, '@id')) {
 934                         return false;
 935                 }
 936
 937                 $object_data = [];
 938                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 939                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 940                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
 941
 942                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
 943                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
 944                         $object_data['reply-to-id'] = $object_data['id'];
 945                 } else {
 946                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 947                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
 948                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
 949                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
 950                                 $object_data['reply-to-id'] = $replyToId;
 951                         }
 952                 }
 953
 954                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 955                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 956
 957                 if (empty($object_data['updated'])) {
 958                         $object_data['updated'] = $object_data['published'];
 959                 }
 960
 961                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 962                         $object_data['published'] = $object_data['updated'];
 963                 }
 964
 965                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
 966                 if (empty($actor)) {
 967                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
 968                 }
 969
 970                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
 971                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
 972                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
 973                 $object_data['actor'] = $object_data['author'] = $actor;
 974                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
 975                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
 976                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 977                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
 978                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
 979                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
 980                 $object_data = self::getSource($object, $object_data);
 981                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
 982                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
 983                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
 984                 $object_data['location'] = JsonLD::fetchElement($object_data, 'location', '@value');
 985                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
 986                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
 987                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
 988                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
 989                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
 990                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
 991                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji'));
 992                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
 993                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
 994                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
 995
 996                 // Special treatment for Hubzilla links
 997                 if (is_array($object_data['alternate-url'])) {
 998                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
 999
1000                         if (!is_string($object_data['alternate-url'])) {
1001                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1002                         }
1003                 }
1004
1005                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1006                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1007                 unset($object_data['receiver']['uid:-1']);
1008
1009                 // Common object data:
1010
1011                 // Unhandled
1012                 // @context, type, actor, signature, mediaType, duration, replies, icon
1013
1014                 // Also missing: (Defined in the standard, but currently unused)
1015                 // audience, preview, endTime, startTime, image
1016
1017                 // Data in Notes:
1018
1019                 // Unhandled
1020                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1021                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1022
1023                 // Data in video:
1024
1025                 // To-Do?
1026                 // category, licence, language, commentsEnabled
1027
1028                 // Unhandled
1029                 // views, waitTranscoding, state, support, subtitleLanguage
1030                 // likes, dislikes, shares, comments
1031
1032                 return $object_data;
1033         }
1034 }