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     Array with activity data
 178          * @param integer $uid          User ID
 179          * @param boolean $push         Message had been pushed to our system
 180          * @param boolean $trust_source Do we trust the source?
 181          *
 182          * @return array with object data
 183          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 184          * @throws \ImagickException
 185          */
 186         private static function prepareObjectData($activity, $uid, $push, &$trust_source)
 187         {
 188                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 189                 if (empty($actor)) {
 190                         Logger::log('Empty actor', Logger::DEBUG);
 191                         return [];
 192                 }
 193
 194                 $type = JsonLD::fetchElement($activity, '@type');
 195
 196                 // Fetch all receivers from to, cc, bto and bcc
 197                 $receivers = self::getReceivers($activity, $actor);
 198
 199                 // When it is a delivery to a personal inbox we add that user to the receivers
 200                 if (!empty($uid)) {
 201                         $additional = ['uid:' . $uid => $uid];
 202                         $receivers = array_merge($receivers, $additional);
 203                 } else {
 204                         // We possibly need some user to fetch private content,
 205                         // so we fetch the first out ot the list.
 206                         $uid = self::getFirstUserFromReceivers($receivers);
 207                 }
 208
 209                 Logger::log('Receivers: ' . $uid . ' - ' . json_encode($receivers), Logger::DEBUG);
 210
 211                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 212                 if (empty($object_id)) {
 213                         Logger::log('No object found', Logger::DEBUG);
 214                         return [];
 215                 }
 216
 217                 if (!is_string($object_id)) {
 218                         Logger::info('Invalid object id', ['object' => $object_id]);
 219                         return [];
 220                 }
 221
 222                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
 223
 224                 // Fetch the content only on activities where this matters
 225                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 226                         if ($type == 'as:Announce') {
 227                                 $trust_source = false;
 228                                 $push = false;
 229                         }
 230                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $uid);
 231                         if (empty($object_data)) {
 232                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
 233                                 return [];
 234                         }
 235
 236                         $object_data['object_id'] = $object_id;
 237                         $object_data['push'] = $push;
 238
 239                         // Test if it is an answer to a mail
 240                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 241                                 $object_data['directmessage'] = true;
 242                         } else {
 243                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 244                         }
 245
 246                         // We had been able to retrieve the object data - so we can trust the source
 247                         $trust_source = true;
 248                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 249                         // Create a mostly empty array out of the activity data (instead of the object).
 250                         // This way we later don't have to check for the existence of ech individual array element.
 251                         $object_data = self::processObject($activity);
 252                         $object_data['name'] = $type;
 253                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 254                         $object_data['object_id'] = $object_id;
 255                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 256                 } elseif (in_array($type, ['as:Add'])) {
 257                         $object_data = [];
 258                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 259                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 260                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 261                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 262                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 263                 } else {
 264                         $object_data = [];
 265                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 266                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 267                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 268                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 269                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 270
 271                         // An Undo is done on the object of an object, so we need that type as well
 272                         if ($type == 'as:Undo') {
 273                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 274                         }
 275                 }
 276
 277                 $object_data = self::addActivityFields($object_data, $activity);
 278
 279                 if (empty($object_data['object_type'])) {
 280                         $object_data['object_type'] = $object_type;
 281                 }
 282
 283                 $object_data['type'] = $type;
 284                 $object_data['actor'] = $actor;
 285                 $object_data['item_receiver'] = $receivers;
 286                 $object_data['receiver'] = array_merge($object_data['receiver'] ?? [], $receivers);
 287
 288                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 289
 290                 return $object_data;
 291         }
 292
 293         /**
 294          * Fetches the first user id from the receiver array
 295          *
 296          * @param array $receivers Array with receivers
 297          * @return integer user id;
 298          */
 299         public static function getFirstUserFromReceivers($receivers)
 300         {
 301                 foreach ($receivers as $receiver) {
 302                         if (!empty($receiver)) {
 303                                 return $receiver;
 304                         }
 305                 }
 306                 return 0;
 307         }
 308
 309         /**
 310          * Processes the activity object
 311          *
 312          * @param array   $activity     Array with activity data
 313          * @param string  $body
 314          * @param integer $uid          User ID
 315          * @param boolean $trust_source Do we trust the source?
 316          * @param boolean $push         Message had been pushed to our system
 317          * @throws \Exception
 318          */
 319         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false, $push = false)
 320         {
 321                 $type = JsonLD::fetchElement($activity, '@type');
 322                 if (!$type) {
 323                         Logger::log('Empty type', Logger::DEBUG);
 324                         return;
 325                 }
 326
 327                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 328                         Logger::log('Empty object', Logger::DEBUG);
 329                         return;
 330                 }
 331
 332                 if (!JsonLD::fetchElement($activity, 'as:actor', '@id')) {
 333                         Logger::log('Empty actor', Logger::DEBUG);
 334                         return;
 335
 336                 }
 337
 338                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
 339                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
 340                         $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 341                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 342                         $trust_source = ($actor == $attributed_to);
 343                         if (!$trust_source) {
 344                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
 345                         }
 346                 }
 347
 348                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 349                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
 350                 if (empty($object_data)) {
 351                         Logger::log('No object data found', Logger::DEBUG);
 352                         return;
 353                 }
 354
 355                 if (!$trust_source) {
 356                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
 357                         return;
 358                 }
 359
 360                 if (!empty($body)) {
 361                         $object_data['raw'] = $body;
 362                 }
 363
 364                 // Internal flag for thread completion. See Processor.php
 365                 if (!empty($activity['thread-completion'])) {
 366                         $object_data['thread-completion'] = $activity['thread-completion'];
 367                 }
 368
 369                 switch ($type) {
 370                         case 'as:Create':
 371                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 372                                         ActivityPub\Processor::createItem($object_data);
 373                                 }
 374                                 break;
 375
 376                         case 'as:Add':
 377                                 if ($object_data['object_type'] == 'as:tag') {
 378                                         ActivityPub\Processor::addTag($object_data);
 379                                 }
 380                                 break;
 381
 382                         case 'as:Announce':
 383                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 384                                         $profile = APContact::getByURL($object_data['actor']);
 385                                         // Reshared posts from persons appear as summary at the bottom
 386                                         // If this isn't set, then a single reshare appears on top. This is used for groups.
 387                                         $object_data['thread-completion'] = ($profile['type'] != 'Group');
 388
 389                                         ActivityPub\Processor::createItem($object_data);
 390
 391                                         // Add the bottom reshare information only for persons
 392                                         if ($profile['type'] != 'Group') {
 393                                                 $announce_object_data = self::processObject($activity);
 394                                                 $announce_object_data['name'] = $type;
 395                                                 $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 396                                                 $announce_object_data['object_id'] = $object_data['object_id'];
 397                                                 $announce_object_data['object_type'] = $object_data['object_type'];
 398
 399                                                 ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 400                                         }
 401                                 }
 402                                 break;
 403
 404                         case 'as:Like':
 405                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 406                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 407                                 }
 408                                 break;
 409
 410                         case 'as:Dislike':
 411                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 412                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 413                                 }
 414                                 break;
 415
 416                         case 'as:TentativeAccept':
 417                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 418                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 419                                 }
 420                                 break;
 421
 422                         case 'as:Update':
 423                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 424                                         ActivityPub\Processor::updateItem($object_data);
 425                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 426                                         ActivityPub\Processor::updatePerson($object_data);
 427                                 }
 428                                 break;
 429
 430                         case 'as:Delete':
 431                                 if ($object_data['object_type'] == 'as:Tombstone') {
 432                                         ActivityPub\Processor::deleteItem($object_data);
 433                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 434                                         ActivityPub\Processor::deletePerson($object_data);
 435                                 }
 436                                 break;
 437
 438                         case 'as:Follow':
 439                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 440                                         ActivityPub\Processor::followUser($object_data);
 441                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 442                                         $object_data['reply-to-id'] = $object_data['object_id'];
 443                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 444                                 }
 445                                 break;
 446
 447                         case 'as:Accept':
 448                                 if ($object_data['object_type'] == 'as:Follow') {
 449                                         ActivityPub\Processor::acceptFollowUser($object_data);
 450                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 451                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 452                                 }
 453                                 break;
 454
 455                         case 'as:Reject':
 456                                 if ($object_data['object_type'] == 'as:Follow') {
 457                                         ActivityPub\Processor::rejectFollowUser($object_data);
 458                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 459                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 460                                 }
 461                                 break;
 462
 463                         case 'as:Undo':
 464                                 if (($object_data['object_type'] == 'as:Follow') &&
 465                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 466                                         ActivityPub\Processor::undoFollowUser($object_data);
 467                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 468                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 469                                         ActivityPub\Processor::rejectFollowUser($object_data);
 470                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 471                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 472                                         ActivityPub\Processor::undoActivity($object_data);
 473                                 }
 474                                 break;
 475
 476                         default:
 477                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 478                                 break;
 479                 }
 480         }
 481
 482         /**
 483          * Fetch the receiver list from an activity array
 484          *
 485          * @param array   $activity
 486          * @param string  $actor
 487          * @param array   $tags
 488          * @param boolean $fetch_unlisted
 489          *
 490          * @return array with receivers (user id)
 491          * @throws \Exception
 492          */
 493         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 494         {
 495                 $receivers = [];
 496
 497                 // When it is an answer, we inherite the receivers from the parent
 498                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 499                 if (!empty($replyto)) {
 500                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 501                         $fixedReplyTo = Item::getURIByLink($replyto);
 502                         $replyto = $fixedReplyTo ?: $replyto;
 503
 504                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 505                         while ($parent = Item::fetch($parents)) {
 506                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 507                         }
 508                 }
 509
 510                 if (!empty($actor)) {
 511                         $profile = APContact::getByURL($actor);
 512                         $followers = $profile['followers'] ?? '';
 513
 514                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 515                 } else {
 516                         Logger::log('Empty actor', Logger::DEBUG);
 517                         $followers = '';
 518                 }
 519
 520                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 521                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 522                         if (empty($receiver_list)) {
 523                                 continue;
 524                         }
 525
 526                         foreach ($receiver_list as $receiver) {
 527                                 if ($receiver == self::PUBLIC_COLLECTION) {
 528                                         $receivers['uid:0'] = 0;
 529                                 }
 530
 531                                 // Add receiver "-1" for unlisted posts
 532                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 533                                         $receivers['uid:-1'] = -1;
 534                                 }
 535
 536                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 537                                         // This will most likely catch all OStatus connections to Mastodon
 538                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 539                                                 , 'archive' => false, 'pending' => false];
 540                                         $contacts = DBA::select('contact', ['uid'], $condition);
 541                                         while ($contact = DBA::fetch($contacts)) {
 542                                                 if ($contact['uid'] != 0) {
 543                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 544                                                 }
 545                                         }
 546                                         DBA::close($contacts);
 547                                 }
 548
 549                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 550                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 551                                         continue;
 552                                 }
 553
 554                                 // Fetching all directly addressed receivers
 555                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 556                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 557                                 if (!DBA::isResult($contact)) {
 558                                         continue;
 559                                 }
 560
 561                                 // Check if the potential receiver is following the actor
 562                                 // Exception: The receiver is targetted via "to" or this is a comment
 563                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 564                                         $networks = Protocol::FEDERATED;
 565                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 566                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 567
 568                                         // Forum posts are only accepted from forum contacts
 569                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 570                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 571                                         }
 572
 573                                         if (!DBA::exists('contact', $condition)) {
 574                                                 continue;
 575                                         }
 576                                 }
 577
 578                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 579                         }
 580                 }
 581
 582                 self::switchContacts($receivers, $actor);
 583
 584                 return $receivers;
 585         }
 586
 587         /**
 588          * Fetch the receiver list of a given actor
 589          *
 590          * @param string $actor
 591          * @param array  $tags
 592          *
 593          * @return array with receivers (user id)
 594          * @throws \Exception
 595          */
 596         public static function getReceiverForActor($actor, $tags)
 597         {
 598                 $receivers = [];
 599                 $networks = Protocol::FEDERATED;
 600                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 601                         'network' => $networks, 'archive' => false, 'pending' => false];
 602                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 603                 while ($contact = DBA::fetch($contacts)) {
 604                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 605                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 606                         }
 607                 }
 608                 DBA::close($contacts);
 609                 return $receivers;
 610         }
 611
 612         /**
 613          * Tests if the contact is a valid receiver for this actor
 614          *
 615          * @param array  $contact
 616          * @param string $actor
 617          * @param array  $tags
 618          *
 619          * @return bool with receivers (user id)
 620          * @throws \Exception
 621          */
 622         private static function isValidReceiverForActor($contact, $actor, $tags)
 623         {
 624                 // Public contacts are no valid receiver
 625                 if ($contact['uid'] == 0) {
 626                         return false;
 627                 }
 628
 629                 // Are we following the contact? Then this is a valid receiver
 630                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 631                         return true;
 632                 }
 633
 634                 // When the possible receiver isn't a community, then it is no valid receiver
 635                 $owner = User::getOwnerDataById($contact['uid']);
 636                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 637                         return false;
 638                 }
 639
 640                 // Is the community account tagged?
 641                 foreach ($tags as $tag) {
 642                         if ($tag['type'] != 'Mention') {
 643                                 continue;
 644                         }
 645
 646                         if ($tag['href'] == $owner['url']) {
 647                                 return true;
 648                         }
 649                 }
 650
 651                 return false;
 652         }
 653
 654         /**
 655          * Switches existing contacts to ActivityPub
 656          *
 657          * @param integer $cid Contact ID
 658          * @param integer $uid User ID
 659          * @param string  $url Profile URL
 660          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 661          * @throws \ImagickException
 662          */
 663         public static function switchContact($cid, $uid, $url)
 664         {
 665                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 666                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 667                         return;
 668                 }
 669
 670                 if (Contact::updateFromProbe($cid, '', true)) {
 671                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 672                 }
 673
 674                 // Send a new follow request to be sure that the connection still exists
 675                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 676                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 677                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 678                 }
 679         }
 680
 681         /**
 682          *
 683          *
 684          * @param $receivers
 685          * @param $actor
 686          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 687          * @throws \ImagickException
 688          */
 689         private static function switchContacts($receivers, $actor)
 690         {
 691                 if (empty($actor)) {
 692                         return;
 693                 }
 694
 695                 foreach ($receivers as $receiver) {
 696                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 697                         if (DBA::isResult($contact)) {
 698                                 self::switchContact($contact['id'], $receiver, $actor);
 699                         }
 700
 701                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 702                         if (DBA::isResult($contact)) {
 703                                 self::switchContact($contact['id'], $receiver, $actor);
 704                         }
 705                 }
 706         }
 707
 708         /**
 709          *
 710          *
 711          * @param       $object_data
 712          * @param array $activity
 713          *
 714          * @return mixed
 715          */
 716         private static function addActivityFields($object_data, $activity)
 717         {
 718                 if (!empty($activity['published']) && empty($object_data['published'])) {
 719                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 720                 }
 721
 722                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 723                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 724                 }
 725
 726                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 727                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 728
 729                 if (!empty($object_data['object_id'])) {
 730                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 731                         $objectId = Item::getURIByLink($object_data['object_id']);
 732                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
 733                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
 734                                 $object_data['object_id'] = $objectId;
 735                         }
 736                 }
 737
 738                 return $object_data;
 739         }
 740
 741         /**
 742          * Fetches the object data from external ressources if needed
 743          *
 744          * @param string  $object_id    Object ID of the the provided object
 745          * @param array   $object       The provided object array
 746          * @param boolean $trust_source Do we trust the provided object?
 747          * @param integer $uid          User ID for the signature that we use to fetch data
 748          *
 749          * @return array|false with trusted and valid object data
 750          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 751          * @throws \ImagickException
 752          */
 753         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
 754         {
 755                 // By fetching the type we check if the object is complete.
 756                 $type = JsonLD::fetchElement($object, '@type');
 757
 758                 if (!$trust_source || empty($type)) {
 759                         $data = ActivityPub::fetchContent($object_id, $uid);
 760                         if (!empty($data)) {
 761                                 $object = JsonLD::compact($data);
 762                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 763                         } else {
 764                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 765
 766                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 767                                 if (!DBA::isResult($item)) {
 768                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 769                                         return false;
 770                                 }
 771                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 772                                 $data = ActivityPub\Transmitter::createNote($item);
 773                                 $object = JsonLD::compact($data);
 774                         }
 775                 } else {
 776                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 777                 }
 778
 779                 $type = JsonLD::fetchElement($object, '@type');
 780
 781                 if (empty($type)) {
 782                         Logger::log('Empty type', Logger::DEBUG);
 783                         return false;
 784                 }
 785
 786                 if (in_array($type, self::CONTENT_TYPES)) {
 787                         $object_data = self::processObject($object);
 788                         if (!empty($data)) {
 789                                 $object_data['raw'] = json_encode($data);
 790                         }
 791                         return $object_data;
 792                 }
 793
 794                 if ($type == 'as:Announce') {
 795                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
 796                         if (empty($object_id) || !is_string($object_id)) {
 797                                 return false;
 798                         }
 799                         return self::fetchObject($object_id, [], false, $uid);
 800                 }
 801
 802                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 803                 return false;
 804         }
 805
 806         /**
 807          * Convert tags from JSON-LD format into a simplified format
 808          *
 809          * @param array $tags Tags in JSON-LD format
 810          *
 811          * @return array with tags in a simplified format
 812          */
 813         private static function processTags($tags)
 814         {
 815                 $taglist = [];
 816
 817                 if (empty($tags)) {
 818                         return [];
 819                 }
 820
 821                 foreach ($tags as $tag) {
 822                         if (empty($tag)) {
 823                                 continue;
 824                         }
 825
 826                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 827                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
 828                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
 829
 830                         if (empty($element['type'])) {
 831                                 continue;
 832                         }
 833
 834                         $taglist[] = $element;
 835                 }
 836                 return $taglist;
 837         }
 838
 839         /**
 840          * Convert emojis from JSON-LD format into a simplified format
 841          *
 842          * @param $emojis
 843          * @return array with emojis in a simplified format
 844          */
 845         private static function processEmojis($emojis)
 846         {
 847                 $emojilist = [];
 848
 849                 if (empty($emojis)) {
 850                         return [];
 851                 }
 852
 853                 foreach ($emojis as $emoji) {
 854                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
 855                                 continue;
 856                         }
 857
 858                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
 859                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
 860                                 'href' => $url];
 861
 862                         $emojilist[] = $element;
 863                 }
 864                 return $emojilist;
 865         }
 866
 867         /**
 868          * Convert attachments from JSON-LD format into a simplified format
 869          *
 870          * @param array $attachments Attachments in JSON-LD format
 871          *
 872          * @return array with attachmants in a simplified format
 873          */
 874         private static function processAttachments($attachments)
 875         {
 876                 $attachlist = [];
 877
 878                 if (empty($attachments)) {
 879                         return [];
 880                 }
 881
 882                 foreach ($attachments as $attachment) {
 883                         if (empty($attachment)) {
 884                                 continue;
 885                         }
 886
 887                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 888                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
 889                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
 890                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')];
 891                 }
 892                 return $attachlist;
 893         }
 894
 895         /**
 896          * Fetch the original source or content with the "language" Markdown or HTML
 897          *
 898          * @param array $object
 899          * @param array $object_data
 900          *
 901          * @return array
 902          * @throws \Exception
 903          */
 904         private static function getSource($object, $object_data)
 905         {
 906                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 907                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 908                 if (!empty($object_data['source'])) {
 909                         return $object_data;
 910                 }
 911
 912                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
 913                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 914                 if (!empty($object_data['source'])) {
 915                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
 916                         return $object_data;
 917                 }
 918
 919                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
 920                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 921                 if (!empty($object_data['source'])) {
 922                         $object_data['source'] = HTML::toBBCode($object_data['source']);
 923                         return $object_data;
 924                 }
 925
 926                 return $object_data;
 927         }
 928
 929         /**
 930          * Fetches data from the object part of an activity
 931          *
 932          * @param array $object
 933          *
 934          * @return array
 935          * @throws \Exception
 936          */
 937         private static function processObject($object)
 938         {
 939                 if (!JsonLD::fetchElement($object, '@id')) {
 940                         return false;
 941                 }
 942
 943                 $object_data = [];
 944                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 945                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 946                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
 947
 948                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
 949                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
 950                         $object_data['reply-to-id'] = $object_data['id'];
 951                 } else {
 952                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 953                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
 954                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
 955                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
 956                                 $object_data['reply-to-id'] = $replyToId;
 957                         }
 958                 }
 959
 960                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 961                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 962
 963                 if (empty($object_data['updated'])) {
 964                         $object_data['updated'] = $object_data['published'];
 965                 }
 966
 967                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 968                         $object_data['published'] = $object_data['updated'];
 969                 }
 970
 971                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
 972                 if (empty($actor)) {
 973                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
 974                 }
 975
 976                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
 977                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
 978                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
 979                 $object_data['actor'] = $object_data['author'] = $actor;
 980                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
 981                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
 982                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 983                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
 984                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
 985                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
 986                 $object_data = self::getSource($object, $object_data);
 987                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
 988                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
 989                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
 990                 $object_data['location'] = JsonLD::fetchElement($object_data, 'location', '@value');
 991                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
 992                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
 993                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
 994                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
 995                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
 996                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
 997                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji'));
 998                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
 999                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
1000                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
1001
1002                 // Special treatment for Hubzilla links
1003                 if (is_array($object_data['alternate-url'])) {
1004                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
1005
1006                         if (!is_string($object_data['alternate-url'])) {
1007                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1008                         }
1009                 }
1010
1011                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1012                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1013                 unset($object_data['receiver']['uid:-1']);
1014
1015                 // Common object data:
1016
1017                 // Unhandled
1018                 // @context, type, actor, signature, mediaType, duration, replies, icon
1019
1020                 // Also missing: (Defined in the standard, but currently unused)
1021                 // audience, preview, endTime, startTime, image
1022
1023                 // Data in Notes:
1024
1025                 // Unhandled
1026                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1027                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1028
1029                 // Data in video:
1030
1031                 // To-Do?
1032                 // category, licence, language, commentsEnabled
1033
1034                 // Unhandled
1035                 // views, waitTranscoding, state, support, subtitleLanguage
1036                 // likes, dislikes, shares, comments
1037
1038                 return $object_data;
1039         }
1040 }