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                         }
 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'] = $object_id;
 236
 237                         if ($type == 'as:Announce') {
 238                                 $object_data['push'] = false;
 239                         } else {
 240                                 $object_data['push'] = $push;
 241                         }
 242
 243                         // Test if it is an answer to a mail
 244                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 245                                 $object_data['directmessage'] = true;
 246                         } else {
 247                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 248                         }
 249
 250                         // We had been able to retrieve the object data - so we can trust the source
 251                         $trust_source = true;
 252                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 253                         // Create a mostly empty array out of the activity data (instead of the object).
 254                         // This way we later don't have to check for the existence of ech individual array element.
 255                         $object_data = self::processObject($activity);
 256                         $object_data['name'] = $type;
 257                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 258                         $object_data['object_id'] = $object_id;
 259                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 260                 } elseif (in_array($type, ['as:Add'])) {
 261                         $object_data = [];
 262                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 263                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 264                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 265                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 266                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 267                 } else {
 268                         $object_data = [];
 269                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 270                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 271                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 272                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 273                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 274
 275                         // An Undo is done on the object of an object, so we need that type as well
 276                         if ($type == 'as:Undo') {
 277                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 278                         }
 279                 }
 280
 281                 $object_data = self::addActivityFields($object_data, $activity);
 282
 283                 if (empty($object_data['object_type'])) {
 284                         $object_data['object_type'] = $object_type;
 285                 }
 286
 287                 $object_data['type'] = $type;
 288                 $object_data['actor'] = $actor;
 289                 $object_data['item_receiver'] = $receivers;
 290                 $object_data['receiver'] = array_merge($object_data['receiver'] ?? [], $receivers);
 291
 292                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 293
 294                 return $object_data;
 295         }
 296
 297         /**
 298          * Fetches the first user id from the receiver array
 299          *
 300          * @param array $receivers Array with receivers
 301          * @return integer user id;
 302          */
 303         public static function getFirstUserFromReceivers($receivers)
 304         {
 305                 foreach ($receivers as $receiver) {
 306                         if (!empty($receiver)) {
 307                                 return $receiver;
 308                         }
 309                 }
 310                 return 0;
 311         }
 312
 313         /**
 314          * Processes the activity object
 315          *
 316          * @param array   $activity     Array with activity data
 317          * @param string  $body
 318          * @param integer $uid          User ID
 319          * @param boolean $trust_source Do we trust the source?
 320          * @param boolean $push         Message had been pushed to our system
 321          * @throws \Exception
 322          */
 323         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false, $push = false)
 324         {
 325                 $type = JsonLD::fetchElement($activity, '@type');
 326                 if (!$type) {
 327                         Logger::log('Empty type', Logger::DEBUG);
 328                         return;
 329                 }
 330
 331                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 332                         Logger::log('Empty object', Logger::DEBUG);
 333                         return;
 334                 }
 335
 336                 if (!JsonLD::fetchElement($activity, 'as:actor', '@id')) {
 337                         Logger::log('Empty actor', Logger::DEBUG);
 338                         return;
 339
 340                 }
 341
 342                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
 343                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
 344                         $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 345                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 346                         $trust_source = ($actor == $attributed_to);
 347                         if (!$trust_source) {
 348                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
 349                         }
 350                 }
 351
 352                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 353                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
 354                 if (empty($object_data)) {
 355                         Logger::log('No object data found', Logger::DEBUG);
 356                         return;
 357                 }
 358
 359                 if (!$trust_source) {
 360                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
 361                         return;
 362                 }
 363
 364                 if (!empty($body) && empty($object_data['raw'])) {
 365                         $object_data['raw'] = $body;
 366                 }
 367
 368                 // Internal flag for thread completion. See Processor.php
 369                 if (!empty($activity['thread-completion'])) {
 370                         $object_data['thread-completion'] = $activity['thread-completion'];
 371                 }
 372
 373                 switch ($type) {
 374                         case 'as:Create':
 375                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 376                                         ActivityPub\Processor::createItem($object_data);
 377                                 }
 378                                 break;
 379
 380                         case 'as:Add':
 381                                 if ($object_data['object_type'] == 'as:tag') {
 382                                         ActivityPub\Processor::addTag($object_data);
 383                                 }
 384                                 break;
 385
 386                         case 'as:Announce':
 387                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 388                                         $profile = APContact::getByURL($object_data['actor']);
 389                                         // Reshared posts from persons appear as summary at the bottom
 390                                         // If this isn't set, then a single reshare appears on top. This is used for groups.
 391                                         $object_data['thread-completion'] = ($profile['type'] != 'Group');
 392
 393                                         ActivityPub\Processor::createItem($object_data);
 394
 395                                         // Add the bottom reshare information only for persons
 396                                         if ($profile['type'] != 'Group') {
 397                                                 $announce_object_data = self::processObject($activity);
 398                                                 $announce_object_data['name'] = $type;
 399                                                 $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 400                                                 $announce_object_data['object_id'] = $object_data['object_id'];
 401                                                 $announce_object_data['object_type'] = $object_data['object_type'];
 402                                                 $announce_object_data['push'] = $push;
 403
 404                                                 if (!empty($body)) {
 405                                                         $announce_object_data['raw'] = $body;
 406                                                 }
 407
 408                                                 ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 409                                         }
 410                                 }
 411                                 break;
 412
 413                         case 'as:Like':
 414                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 415                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 416                                 }
 417                                 break;
 418
 419                         case 'as:Dislike':
 420                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 421                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 422                                 }
 423                                 break;
 424
 425                         case 'as:TentativeAccept':
 426                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 427                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 428                                 }
 429                                 break;
 430
 431                         case 'as:Update':
 432                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 433                                         ActivityPub\Processor::updateItem($object_data);
 434                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 435                                         ActivityPub\Processor::updatePerson($object_data);
 436                                 }
 437                                 break;
 438
 439                         case 'as:Delete':
 440                                 if ($object_data['object_type'] == 'as:Tombstone') {
 441                                         ActivityPub\Processor::deleteItem($object_data);
 442                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 443                                         ActivityPub\Processor::deletePerson($object_data);
 444                                 }
 445                                 break;
 446
 447                         case 'as:Follow':
 448                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 449                                         ActivityPub\Processor::followUser($object_data);
 450                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 451                                         $object_data['reply-to-id'] = $object_data['object_id'];
 452                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 453                                 }
 454                                 break;
 455
 456                         case 'as:Accept':
 457                                 if ($object_data['object_type'] == 'as:Follow') {
 458                                         ActivityPub\Processor::acceptFollowUser($object_data);
 459                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 460                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 461                                 }
 462                                 break;
 463
 464                         case 'as:Reject':
 465                                 if ($object_data['object_type'] == 'as:Follow') {
 466                                         ActivityPub\Processor::rejectFollowUser($object_data);
 467                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 468                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 469                                 }
 470                                 break;
 471
 472                         case 'as:Undo':
 473                                 if (($object_data['object_type'] == 'as:Follow') &&
 474                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 475                                         ActivityPub\Processor::undoFollowUser($object_data);
 476                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 477                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 478                                         ActivityPub\Processor::rejectFollowUser($object_data);
 479                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 480                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 481                                         ActivityPub\Processor::undoActivity($object_data);
 482                                 }
 483                                 break;
 484
 485                         default:
 486                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 487                                 break;
 488                 }
 489         }
 490
 491         /**
 492          * Fetch the receiver list from an activity array
 493          *
 494          * @param array   $activity
 495          * @param string  $actor
 496          * @param array   $tags
 497          * @param boolean $fetch_unlisted
 498          *
 499          * @return array with receivers (user id)
 500          * @throws \Exception
 501          */
 502         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 503         {
 504                 $receivers = [];
 505
 506                 // When it is an answer, we inherite the receivers from the parent
 507                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 508                 if (!empty($replyto)) {
 509                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 510                         $fixedReplyTo = Item::getURIByLink($replyto);
 511                         $replyto = $fixedReplyTo ?: $replyto;
 512
 513                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 514                         while ($parent = Item::fetch($parents)) {
 515                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 516                         }
 517                 }
 518
 519                 if (!empty($actor)) {
 520                         $profile = APContact::getByURL($actor);
 521                         $followers = $profile['followers'] ?? '';
 522
 523                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 524                 } else {
 525                         Logger::log('Empty actor', Logger::DEBUG);
 526                         $followers = '';
 527                 }
 528
 529                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 530                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 531                         if (empty($receiver_list)) {
 532                                 continue;
 533                         }
 534
 535                         foreach ($receiver_list as $receiver) {
 536                                 if ($receiver == self::PUBLIC_COLLECTION) {
 537                                         $receivers['uid:0'] = 0;
 538                                 }
 539
 540                                 // Add receiver "-1" for unlisted posts
 541                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 542                                         $receivers['uid:-1'] = -1;
 543                                 }
 544
 545                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 546                                         // This will most likely catch all OStatus connections to Mastodon
 547                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 548                                                 , 'archive' => false, 'pending' => false];
 549                                         $contacts = DBA::select('contact', ['uid'], $condition);
 550                                         while ($contact = DBA::fetch($contacts)) {
 551                                                 if ($contact['uid'] != 0) {
 552                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 553                                                 }
 554                                         }
 555                                         DBA::close($contacts);
 556                                 }
 557
 558                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 559                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 560                                         continue;
 561                                 }
 562
 563                                 // Fetching all directly addressed receivers
 564                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 565                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 566                                 if (!DBA::isResult($contact)) {
 567                                         continue;
 568                                 }
 569
 570                                 // Check if the potential receiver is following the actor
 571                                 // Exception: The receiver is targetted via "to" or this is a comment
 572                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 573                                         $networks = Protocol::FEDERATED;
 574                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 575                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 576
 577                                         // Forum posts are only accepted from forum contacts
 578                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 579                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 580                                         }
 581
 582                                         if (!DBA::exists('contact', $condition)) {
 583                                                 continue;
 584                                         }
 585                                 }
 586
 587                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 588                         }
 589                 }
 590
 591                 self::switchContacts($receivers, $actor);
 592
 593                 return $receivers;
 594         }
 595
 596         /**
 597          * Fetch the receiver list of a given actor
 598          *
 599          * @param string $actor
 600          * @param array  $tags
 601          *
 602          * @return array with receivers (user id)
 603          * @throws \Exception
 604          */
 605         public static function getReceiverForActor($actor, $tags)
 606         {
 607                 $receivers = [];
 608                 $networks = Protocol::FEDERATED;
 609                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 610                         'network' => $networks, 'archive' => false, 'pending' => false];
 611                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 612                 while ($contact = DBA::fetch($contacts)) {
 613                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 614                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 615                         }
 616                 }
 617                 DBA::close($contacts);
 618                 return $receivers;
 619         }
 620
 621         /**
 622          * Tests if the contact is a valid receiver for this actor
 623          *
 624          * @param array  $contact
 625          * @param string $actor
 626          * @param array  $tags
 627          *
 628          * @return bool with receivers (user id)
 629          * @throws \Exception
 630          */
 631         private static function isValidReceiverForActor($contact, $actor, $tags)
 632         {
 633                 // Public contacts are no valid receiver
 634                 if ($contact['uid'] == 0) {
 635                         return false;
 636                 }
 637
 638                 // Are we following the contact? Then this is a valid receiver
 639                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 640                         return true;
 641                 }
 642
 643                 // When the possible receiver isn't a community, then it is no valid receiver
 644                 $owner = User::getOwnerDataById($contact['uid']);
 645                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 646                         return false;
 647                 }
 648
 649                 // Is the community account tagged?
 650                 foreach ($tags as $tag) {
 651                         if ($tag['type'] != 'Mention') {
 652                                 continue;
 653                         }
 654
 655                         if ($tag['href'] == $owner['url']) {
 656                                 return true;
 657                         }
 658                 }
 659
 660                 return false;
 661         }
 662
 663         /**
 664          * Switches existing contacts to ActivityPub
 665          *
 666          * @param integer $cid Contact ID
 667          * @param integer $uid User ID
 668          * @param string  $url Profile URL
 669          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 670          * @throws \ImagickException
 671          */
 672         public static function switchContact($cid, $uid, $url)
 673         {
 674                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 675                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 676                         return;
 677                 }
 678
 679                 if (Contact::updateFromProbe($cid, '', true)) {
 680                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 681                 }
 682
 683                 // Send a new follow request to be sure that the connection still exists
 684                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 685                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 686                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 687                 }
 688         }
 689
 690         /**
 691          *
 692          *
 693          * @param $receivers
 694          * @param $actor
 695          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 696          * @throws \ImagickException
 697          */
 698         private static function switchContacts($receivers, $actor)
 699         {
 700                 if (empty($actor)) {
 701                         return;
 702                 }
 703
 704                 foreach ($receivers as $receiver) {
 705                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 706                         if (DBA::isResult($contact)) {
 707                                 self::switchContact($contact['id'], $receiver, $actor);
 708                         }
 709
 710                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 711                         if (DBA::isResult($contact)) {
 712                                 self::switchContact($contact['id'], $receiver, $actor);
 713                         }
 714                 }
 715         }
 716
 717         /**
 718          *
 719          *
 720          * @param       $object_data
 721          * @param array $activity
 722          *
 723          * @return mixed
 724          */
 725         private static function addActivityFields($object_data, $activity)
 726         {
 727                 if (!empty($activity['published']) && empty($object_data['published'])) {
 728                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 729                 }
 730
 731                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 732                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 733                 }
 734
 735                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 736                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 737
 738                 if (!empty($object_data['object_id'])) {
 739                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 740                         $objectId = Item::getURIByLink($object_data['object_id']);
 741                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
 742                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
 743                                 $object_data['object_id'] = $objectId;
 744                         }
 745                 }
 746
 747                 return $object_data;
 748         }
 749
 750         /**
 751          * Fetches the object data from external ressources if needed
 752          *
 753          * @param string  $object_id    Object ID of the the provided object
 754          * @param array   $object       The provided object array
 755          * @param boolean $trust_source Do we trust the provided object?
 756          * @param integer $uid          User ID for the signature that we use to fetch data
 757          *
 758          * @return array|false with trusted and valid object data
 759          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 760          * @throws \ImagickException
 761          */
 762         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
 763         {
 764                 // By fetching the type we check if the object is complete.
 765                 $type = JsonLD::fetchElement($object, '@type');
 766
 767                 if (!$trust_source || empty($type)) {
 768                         $data = ActivityPub::fetchContent($object_id, $uid);
 769                         if (!empty($data)) {
 770                                 $object = JsonLD::compact($data);
 771                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 772                         } else {
 773                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 774
 775                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 776                                 if (!DBA::isResult($item)) {
 777                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 778                                         return false;
 779                                 }
 780                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 781                                 $data = ActivityPub\Transmitter::createNote($item);
 782                                 $object = JsonLD::compact($data);
 783                         }
 784                 } else {
 785                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 786                 }
 787
 788                 $type = JsonLD::fetchElement($object, '@type');
 789
 790                 if (empty($type)) {
 791                         Logger::log('Empty type', Logger::DEBUG);
 792                         return false;
 793                 }
 794
 795                 if (in_array($type, self::CONTENT_TYPES)) {
 796                         $object_data = self::processObject($object);
 797
 798                         if (!empty($data)) {
 799                                 $object_data['raw'] = json_encode($data);
 800                         }
 801                         return $object_data;
 802                 }
 803
 804                 if ($type == 'as:Announce') {
 805                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
 806                         if (empty($object_id) || !is_string($object_id)) {
 807                                 return false;
 808                         }
 809                         return self::fetchObject($object_id, [], false, $uid);
 810                 }
 811
 812                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 813                 return false;
 814         }
 815
 816         /**
 817          * Convert tags from JSON-LD format into a simplified format
 818          *
 819          * @param array $tags Tags in JSON-LD format
 820          *
 821          * @return array with tags in a simplified format
 822          */
 823         private static function processTags($tags)
 824         {
 825                 $taglist = [];
 826
 827                 if (empty($tags)) {
 828                         return [];
 829                 }
 830
 831                 foreach ($tags as $tag) {
 832                         if (empty($tag)) {
 833                                 continue;
 834                         }
 835
 836                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 837                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
 838                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
 839
 840                         if (empty($element['type'])) {
 841                                 continue;
 842                         }
 843
 844                         $taglist[] = $element;
 845                 }
 846                 return $taglist;
 847         }
 848
 849         /**
 850          * Convert emojis from JSON-LD format into a simplified format
 851          *
 852          * @param $emojis
 853          * @return array with emojis in a simplified format
 854          */
 855         private static function processEmojis($emojis)
 856         {
 857                 $emojilist = [];
 858
 859                 if (empty($emojis)) {
 860                         return [];
 861                 }
 862
 863                 foreach ($emojis as $emoji) {
 864                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
 865                                 continue;
 866                         }
 867
 868                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
 869                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
 870                                 'href' => $url];
 871
 872                         $emojilist[] = $element;
 873                 }
 874                 return $emojilist;
 875         }
 876
 877         /**
 878          * Convert attachments from JSON-LD format into a simplified format
 879          *
 880          * @param array $attachments Attachments in JSON-LD format
 881          *
 882          * @return array with attachmants in a simplified format
 883          */
 884         private static function processAttachments($attachments)
 885         {
 886                 $attachlist = [];
 887
 888                 if (empty($attachments)) {
 889                         return [];
 890                 }
 891
 892                 foreach ($attachments as $attachment) {
 893                         if (empty($attachment)) {
 894                                 continue;
 895                         }
 896
 897                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 898                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
 899                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
 900                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')];
 901                 }
 902                 return $attachlist;
 903         }
 904
 905         /**
 906          * Fetch the original source or content with the "language" Markdown or HTML
 907          *
 908          * @param array $object
 909          * @param array $object_data
 910          *
 911          * @return array
 912          * @throws \Exception
 913          */
 914         private static function getSource($object, $object_data)
 915         {
 916                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 917                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 918                 if (!empty($object_data['source'])) {
 919                         return $object_data;
 920                 }
 921
 922                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
 923                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 924                 if (!empty($object_data['source'])) {
 925                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
 926                         return $object_data;
 927                 }
 928
 929                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
 930                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 931                 if (!empty($object_data['source'])) {
 932                         $object_data['source'] = HTML::toBBCode($object_data['source']);
 933                         return $object_data;
 934                 }
 935
 936                 return $object_data;
 937         }
 938
 939         /**
 940          * Fetches data from the object part of an activity
 941          *
 942          * @param array $object
 943          *
 944          * @return array
 945          * @throws \Exception
 946          */
 947         private static function processObject($object)
 948         {
 949                 if (!JsonLD::fetchElement($object, '@id')) {
 950                         return false;
 951                 }
 952
 953                 $object_data = [];
 954                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
 955                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
 956                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
 957
 958                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
 959                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
 960                         $object_data['reply-to-id'] = $object_data['id'];
 961                 } else {
 962                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 963                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
 964                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
 965                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
 966                                 $object_data['reply-to-id'] = $replyToId;
 967                         }
 968                 }
 969
 970                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
 971                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
 972
 973                 if (empty($object_data['updated'])) {
 974                         $object_data['updated'] = $object_data['published'];
 975                 }
 976
 977                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 978                         $object_data['published'] = $object_data['updated'];
 979                 }
 980
 981                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
 982                 if (empty($actor)) {
 983                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
 984                 }
 985
 986                 $object_data['sc:identifier'] = JsonLD::fetchElement($object, 'sc:identifier', '@value');
 987                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
 988                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
 989                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
 990                 $object_data['actor'] = $object_data['author'] = $actor;
 991                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
 992                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
 993                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
 994                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
 995                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
 996                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
 997                 $object_data = self::getSource($object, $object_data);
 998                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
 999                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
1000                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
1001                 $object_data['location'] = JsonLD::fetchElement($object_data, 'location', '@value');
1002                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
1003                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
1004                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
1005                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
1006                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
1007                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
1008                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji'));
1009                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
1010                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
1011                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
1012
1013                 // Special treatment for Hubzilla links
1014                 if (is_array($object_data['alternate-url'])) {
1015                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
1016
1017                         if (!is_string($object_data['alternate-url'])) {
1018                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1019                         }
1020                 }
1021
1022                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1023                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1024                 unset($object_data['receiver']['uid:-1']);
1025
1026                 // Common object data:
1027
1028                 // Unhandled
1029                 // @context, type, actor, signature, mediaType, duration, replies, icon
1030
1031                 // Also missing: (Defined in the standard, but currently unused)
1032                 // audience, preview, endTime, startTime, image
1033
1034                 // Data in Notes:
1035
1036                 // Unhandled
1037                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1038                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1039
1040                 // Data in video:
1041
1042                 // To-Do?
1043                 // category, licence, language, commentsEnabled
1044
1045                 // Unhandled
1046                 // views, waitTranscoding, state, support, subtitleLanguage
1047                 // likes, dislikes, shares, comments
1048
1049                 return $object_data;
1050         }
1051 }