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\Content\Text\BBCode;
  25 use Friendica\Database\DBA;
  26 use Friendica\Content\Text\HTML;
  27 use Friendica\Content\Text\Markdown;
  28 use Friendica\Core\Logger;
  29 use Friendica\Core\Protocol;
  30 use Friendica\Model\Contact;
  31 use Friendica\Model\APContact;
  32 use Friendica\Model\Item;
  33 use Friendica\Model\User;
  34 use Friendica\Protocol\Activity;
  35 use Friendica\Protocol\ActivityPub;
  36 use Friendica\Util\DateTimeFormat;
  37 use Friendica\Util\HTTPSignature;
  38 use Friendica\Util\JsonLD;
  39 use Friendica\Util\LDSignature;
  40 use Friendica\Util\Strings;
  41
  42 /**
  43  * ActivityPub Receiver Protocol class
  44  *
  45  * To-Do:
  46  * @todo Undo Announce
  47  *
  48  * Check what this is meant to do:
  49  * - Add
  50  * - Block
  51  * - Flag
  52  * - Remove
  53  * - Undo Block
  54  */
  55 class Receiver
  56 {
  57         const PUBLIC_COLLECTION = 'as:Public';
  58         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
  59         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event', 'as:Audio'];
  60         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
  61
  62         /**
  63          * Checks if the web request is done for the AP protocol
  64          *
  65          * @return bool is it AP?
  66          */
  67         public static function isRequest()
  68         {
  69                 return stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/activity+json') ||
  70                         stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/ld+json');
  71         }
  72
  73         /**
  74          * Checks incoming message from the inbox
  75          *
  76          * @param         $body
  77          * @param         $header
  78          * @param integer $uid User ID
  79          * @throws \Exception
  80          */
  81         public static function processInbox($body, $header, $uid)
  82         {
  83                 $http_signer = HTTPSignature::getSigner($body, $header);
  84                 if (empty($http_signer)) {
  85                         Logger::warning('Invalid HTTP signature, message will be discarded.');
  86                         return;
  87                 } else {
  88                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
  89                 }
  90
  91                 $activity = json_decode($body, true);
  92
  93                 if (empty($activity)) {
  94                         Logger::warning('Invalid body.');
  95                         return;
  96                 }
  97
  98                 $ldactivity = JsonLD::compact($activity);
  99
 100                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor', '@id');
 101
 102                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
 103
 104                 if (LDSignature::isSigned($activity)) {
 105                         $ld_signer = LDSignature::getSigner($activity);
 106                         if (empty($ld_signer)) {
 107                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
 108                         }
 109                         if (!empty($ld_signer && ($actor == $http_signer))) {
 110                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
 111                                 $trust_source = true;
 112                         } elseif (!empty($ld_signer)) {
 113                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
 114                                 $trust_source = true;
 115                         } elseif ($actor == $http_signer) {
 116                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
 117                                 $trust_source = true;
 118                         } else {
 119                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
 120                                 $trust_source = false;
 121                         }
 122                 } elseif ($actor == $http_signer) {
 123                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
 124                         $trust_source = true;
 125                 } else {
 126                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
 127                         $trust_source = false;
 128                 }
 129
 130                 self::processActivity($ldactivity, $body, $uid, $trust_source, true);
 131         }
 132
 133         /**
 134          * Fetches the object type for a given object id
 135          *
 136          * @param array   $activity
 137          * @param string  $object_id Object ID of the the provided object
 138          * @param integer $uid       User ID
 139          *
 140          * @return string with object type
 141          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 142          * @throws \ImagickException
 143          */
 144         private static function fetchObjectType($activity, $object_id, $uid = 0)
 145         {
 146                 if (!empty($activity['as:object'])) {
 147                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
 148                         if (!empty($object_type)) {
 149                                 return $object_type;
 150                         }
 151                 }
 152
 153                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
 154                         // We just assume "note" since it doesn't make a difference for the further processing
 155                         return 'as:Note';
 156                 }
 157
 158                 $profile = APContact::getByURL($object_id);
 159                 if (!empty($profile['type'])) {
 160                         return 'as:' . $profile['type'];
 161                 }
 162
 163                 $data = ActivityPub::fetchContent($object_id, $uid);
 164                 if (!empty($data)) {
 165                         $object = JsonLD::compact($data);
 166                         $type = JsonLD::fetchElement($object, '@type');
 167                         if (!empty($type)) {
 168                                 return $type;
 169                         }
 170                 }
 171
 172                 return null;
 173         }
 174
 175         /**
 176          * Prepare the object array
 177          *
 178          * @param array   $activity     Array with activity data
 179          * @param integer $uid          User ID
 180          * @param boolean $push         Message had been pushed to our system
 181          * @param boolean $trust_source Do we trust the source?
 182          *
 183          * @return array with object data
 184          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 185          * @throws \ImagickException
 186          */
 187         private static function prepareObjectData($activity, $uid, $push, &$trust_source)
 188         {
 189                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 190                 if (empty($actor)) {
 191                         Logger::log('Empty actor', Logger::DEBUG);
 192                         return [];
 193                 }
 194
 195                 $type = JsonLD::fetchElement($activity, '@type');
 196
 197                 // Fetch all receivers from to, cc, bto and bcc
 198                 $receivers = self::getReceivers($activity, $actor);
 199
 200                 // When it is a delivery to a personal inbox we add that user to the receivers
 201                 if (!empty($uid)) {
 202                         $additional = ['uid:' . $uid => $uid];
 203                         $receivers = array_merge($receivers, $additional);
 204                 } else {
 205                         // We possibly need some user to fetch private content,
 206                         // so we fetch the first out ot the list.
 207                         $uid = self::getFirstUserFromReceivers($receivers);
 208                 }
 209
 210                 Logger::log('Receivers: ' . $uid . ' - ' . json_encode($receivers), Logger::DEBUG);
 211
 212                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
 213                 if (empty($object_id)) {
 214                         Logger::log('No object found', Logger::DEBUG);
 215                         return [];
 216                 }
 217
 218                 if (!is_string($object_id)) {
 219                         Logger::info('Invalid object id', ['object' => $object_id]);
 220                         return [];
 221                 }
 222
 223                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
 224
 225                 // Fetch the content only on activities where this matters
 226                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 227                         if ($type == 'as:Announce') {
 228                                 $trust_source = 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'] = $object_id;
 237
 238                         if ($type == 'as:Announce') {
 239                                 $object_data['push'] = false;
 240                         } else {
 241                                 $object_data['push'] = $push;
 242                         }
 243
 244                         // Test if it is an answer to a mail
 245                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
 246                                 $object_data['directmessage'] = true;
 247                         } else {
 248                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
 249                         }
 250
 251                         // We had been able to retrieve the object data - so we can trust the source
 252                         $trust_source = true;
 253                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
 254                         // Create a mostly empty array out of the activity data (instead of the object).
 255                         // This way we later don't have to check for the existence of ech individual array element.
 256                         $object_data = self::processObject($activity);
 257                         $object_data['name'] = $type;
 258                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 259                         $object_data['object_id'] = $object_id;
 260                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
 261                 } elseif (in_array($type, ['as:Add'])) {
 262                         $object_data = [];
 263                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 264                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
 265                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 266                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 267                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 268                 } else {
 269                         $object_data = [];
 270                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
 271                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
 272                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
 273                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 274                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
 275
 276                         // An Undo is done on the object of an object, so we need that type as well
 277                         if (($type == 'as:Undo') && !empty($object_data['object_object'])) {
 278                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
 279                         }
 280                 }
 281
 282                 $object_data = self::addActivityFields($object_data, $activity);
 283
 284                 if (empty($object_data['object_type'])) {
 285                         $object_data['object_type'] = $object_type;
 286                 }
 287
 288                 $object_data['type'] = $type;
 289                 $object_data['actor'] = $actor;
 290                 $object_data['item_receiver'] = $receivers;
 291                 $object_data['receiver'] = array_merge($object_data['receiver'] ?? [], $receivers);
 292
 293                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
 294
 295                 return $object_data;
 296         }
 297
 298         /**
 299          * Fetches the first user id from the receiver array
 300          *
 301          * @param array $receivers Array with receivers
 302          * @return integer user id;
 303          */
 304         public static function getFirstUserFromReceivers($receivers)
 305         {
 306                 foreach ($receivers as $receiver) {
 307                         if (!empty($receiver)) {
 308                                 return $receiver;
 309                         }
 310                 }
 311                 return 0;
 312         }
 313
 314         /**
 315          * Processes the activity object
 316          *
 317          * @param array   $activity     Array with activity data
 318          * @param string  $body
 319          * @param integer $uid          User ID
 320          * @param boolean $trust_source Do we trust the source?
 321          * @param boolean $push         Message had been pushed to our system
 322          * @throws \Exception
 323          */
 324         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false, $push = false)
 325         {
 326                 $type = JsonLD::fetchElement($activity, '@type');
 327                 if (!$type) {
 328                         Logger::log('Empty type', Logger::DEBUG);
 329                         return;
 330                 }
 331
 332                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
 333                         Logger::log('Empty object', Logger::DEBUG);
 334                         return;
 335                 }
 336
 337                 if (!JsonLD::fetchElement($activity, 'as:actor', '@id')) {
 338                         Logger::log('Empty actor', Logger::DEBUG);
 339                         return;
 340
 341                 }
 342
 343                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
 344                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
 345                         $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
 346                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
 347                         $trust_source = ($actor == $attributed_to);
 348                         if (!$trust_source) {
 349                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
 350                         }
 351                 }
 352
 353                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
 354                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
 355                 if (empty($object_data)) {
 356                         Logger::log('No object data found', Logger::DEBUG);
 357                         return;
 358                 }
 359
 360                 if (!$trust_source) {
 361                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
 362                         return;
 363                 }
 364
 365                 if (!empty($body) && empty($object_data['raw'])) {
 366                         $object_data['raw'] = $body;
 367                 }
 368
 369                 // Internal flag for thread completion. See Processor.php
 370                 if (!empty($activity['thread-completion'])) {
 371                         $object_data['thread-completion'] = $activity['thread-completion'];
 372                 }
 373
 374                 switch ($type) {
 375                         case 'as:Create':
 376                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 377                                         ActivityPub\Processor::createItem($object_data);
 378                                 }
 379                                 break;
 380
 381                         case 'as:Add':
 382                                 if ($object_data['object_type'] == 'as:tag') {
 383                                         ActivityPub\Processor::addTag($object_data);
 384                                 }
 385                                 break;
 386
 387                         case 'as:Announce':
 388                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 389                                         $profile = APContact::getByURL($object_data['actor']);
 390                                         // Reshared posts from persons appear as summary at the bottom
 391                                         // If this isn't set, then a single reshare appears on top. This is used for groups.
 392                                         $object_data['thread-completion'] = ($profile['type'] != 'Group');
 393
 394                                         ActivityPub\Processor::createItem($object_data);
 395
 396                                         // Add the bottom reshare information only for persons
 397                                         if ($profile['type'] != 'Group') {
 398                                                 $announce_object_data = self::processObject($activity);
 399                                                 $announce_object_data['name'] = $type;
 400                                                 $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 401                                                 $announce_object_data['object_id'] = $object_data['object_id'];
 402                                                 $announce_object_data['object_type'] = $object_data['object_type'];
 403                                                 $announce_object_data['push'] = $push;
 404
 405                                                 if (!empty($body)) {
 406                                                         $announce_object_data['raw'] = $body;
 407                                                 }
 408
 409                                                 ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
 410                                         }
 411                                 }
 412                                 break;
 413
 414                         case 'as:Like':
 415                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 416                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
 417                                 }
 418                                 break;
 419
 420                         case 'as:Dislike':
 421                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 422                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
 423                                 }
 424                                 break;
 425
 426                         case 'as:TentativeAccept':
 427                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 428                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
 429                                 }
 430                                 break;
 431
 432                         case 'as:Update':
 433                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 434                                         ActivityPub\Processor::updateItem($object_data);
 435                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 436                                         ActivityPub\Processor::updatePerson($object_data);
 437                                 }
 438                                 break;
 439
 440                         case 'as:Delete':
 441                                 if ($object_data['object_type'] == 'as:Tombstone') {
 442                                         ActivityPub\Processor::deleteItem($object_data);
 443                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 444                                         ActivityPub\Processor::deletePerson($object_data);
 445                                 }
 446                                 break;
 447
 448                         case 'as:Follow':
 449                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 450                                         ActivityPub\Processor::followUser($object_data);
 451                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 452                                         $object_data['reply-to-id'] = $object_data['object_id'];
 453                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
 454                                 }
 455                                 break;
 456
 457                         case 'as:Accept':
 458                                 if ($object_data['object_type'] == 'as:Follow') {
 459                                         ActivityPub\Processor::acceptFollowUser($object_data);
 460                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 461                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
 462                                 }
 463                                 break;
 464
 465                         case 'as:Reject':
 466                                 if ($object_data['object_type'] == 'as:Follow') {
 467                                         ActivityPub\Processor::rejectFollowUser($object_data);
 468                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 469                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
 470                                 }
 471                                 break;
 472
 473                         case 'as:Undo':
 474                                 if (($object_data['object_type'] == 'as:Follow') &&
 475                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 476                                         ActivityPub\Processor::undoFollowUser($object_data);
 477                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
 478                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 479                                         ActivityPub\Processor::rejectFollowUser($object_data);
 480                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
 481                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 482                                         ActivityPub\Processor::undoActivity($object_data);
 483                                 }
 484                                 break;
 485
 486                         default:
 487                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
 488                                 break;
 489                 }
 490         }
 491
 492         /**
 493          * Fetch the receiver list from an activity array
 494          *
 495          * @param array   $activity
 496          * @param string  $actor
 497          * @param array   $tags
 498          * @param boolean $fetch_unlisted
 499          *
 500          * @return array with receivers (user id)
 501          * @throws \Exception
 502          */
 503         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
 504         {
 505                 $receivers = [];
 506
 507                 // When it is an answer, we inherite the receivers from the parent
 508                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
 509                 if (!empty($replyto)) {
 510                         // Fix possibly wrong item URI (could be an answer to a plink uri)
 511                         $fixedReplyTo = Item::getURIByLink($replyto);
 512                         $replyto = $fixedReplyTo ?: $replyto;
 513
 514                         $parents = Item::select(['uid'], ['uri' => $replyto]);
 515                         while ($parent = Item::fetch($parents)) {
 516                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
 517                         }
 518                 }
 519
 520                 if (!empty($actor)) {
 521                         $profile = APContact::getByURL($actor);
 522                         $followers = $profile['followers'] ?? '';
 523
 524                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
 525                 } else {
 526                         Logger::log('Empty actor', Logger::DEBUG);
 527                         $followers = '';
 528                 }
 529
 530                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
 531                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
 532                         if (empty($receiver_list)) {
 533                                 continue;
 534                         }
 535
 536                         foreach ($receiver_list as $receiver) {
 537                                 if ($receiver == self::PUBLIC_COLLECTION) {
 538                                         $receivers['uid:0'] = 0;
 539                                 }
 540
 541                                 // Add receiver "-1" for unlisted posts
 542                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
 543                                         $receivers['uid:-1'] = -1;
 544                                 }
 545
 546                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
 547                                         // This will most likely catch all OStatus connections to Mastodon
 548                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
 549                                                 , 'archive' => false, 'pending' => false];
 550                                         $contacts = DBA::select('contact', ['uid'], $condition);
 551                                         while ($contact = DBA::fetch($contacts)) {
 552                                                 if ($contact['uid'] != 0) {
 553                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 554                                                 }
 555                                         }
 556                                         DBA::close($contacts);
 557                                 }
 558
 559                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
 560                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
 561                                         continue;
 562                                 }
 563
 564                                 // Fetching all directly addressed receivers
 565                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
 566                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
 567                                 if (!DBA::isResult($contact)) {
 568                                         continue;
 569                                 }
 570
 571                                 // Check if the potential receiver is following the actor
 572                                 // Exception: The receiver is targetted via "to" or this is a comment
 573                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
 574                                         $networks = Protocol::FEDERATED;
 575                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 576                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
 577
 578                                         // Forum posts are only accepted from forum contacts
 579                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
 580                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
 581                                         }
 582
 583                                         if (!DBA::exists('contact', $condition)) {
 584                                                 continue;
 585                                         }
 586                                 }
 587
 588                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 589                         }
 590                 }
 591
 592                 self::switchContacts($receivers, $actor);
 593
 594                 return $receivers;
 595         }
 596
 597         /**
 598          * Fetch the receiver list of a given actor
 599          *
 600          * @param string $actor
 601          * @param array  $tags
 602          *
 603          * @return array with receivers (user id)
 604          * @throws \Exception
 605          */
 606         public static function getReceiverForActor($actor, $tags)
 607         {
 608                 $receivers = [];
 609                 $networks = Protocol::FEDERATED;
 610                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
 611                         'network' => $networks, 'archive' => false, 'pending' => false];
 612                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
 613                 while ($contact = DBA::fetch($contacts)) {
 614                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
 615                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 616                         }
 617                 }
 618                 DBA::close($contacts);
 619                 return $receivers;
 620         }
 621
 622         /**
 623          * Tests if the contact is a valid receiver for this actor
 624          *
 625          * @param array  $contact
 626          * @param string $actor
 627          * @param array  $tags
 628          *
 629          * @return bool with receivers (user id)
 630          * @throws \Exception
 631          */
 632         private static function isValidReceiverForActor($contact, $actor, $tags)
 633         {
 634                 // Public contacts are no valid receiver
 635                 if ($contact['uid'] == 0) {
 636                         return false;
 637                 }
 638
 639                 // Are we following the contact? Then this is a valid receiver
 640                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
 641                         return true;
 642                 }
 643
 644                 // When the possible receiver isn't a community, then it is no valid receiver
 645                 $owner = User::getOwnerDataById($contact['uid']);
 646                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
 647                         return false;
 648                 }
 649
 650                 // Is the community account tagged?
 651                 foreach ($tags as $tag) {
 652                         if ($tag['type'] != 'Mention') {
 653                                 continue;
 654                         }
 655
 656                         if ($tag['href'] == $owner['url']) {
 657                                 return true;
 658                         }
 659                 }
 660
 661                 return false;
 662         }
 663
 664         /**
 665          * Switches existing contacts to ActivityPub
 666          *
 667          * @param integer $cid Contact ID
 668          * @param integer $uid User ID
 669          * @param string  $url Profile URL
 670          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 671          * @throws \ImagickException
 672          */
 673         public static function switchContact($cid, $uid, $url)
 674         {
 675                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
 676                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 677                         return;
 678                 }
 679
 680                 if (Contact::updateFromProbe($cid, '', true)) {
 681                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
 682                 }
 683
 684                 // Send a new follow request to be sure that the connection still exists
 685                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
 686                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
 687                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
 688                 }
 689         }
 690
 691         /**
 692          *
 693          *
 694          * @param $receivers
 695          * @param $actor
 696          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 697          * @throws \ImagickException
 698          */
 699         private static function switchContacts($receivers, $actor)
 700         {
 701                 if (empty($actor)) {
 702                         return;
 703                 }
 704
 705                 foreach ($receivers as $receiver) {
 706                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
 707                         if (DBA::isResult($contact)) {
 708                                 self::switchContact($contact['id'], $receiver, $actor);
 709                         }
 710
 711                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
 712                         if (DBA::isResult($contact)) {
 713                                 self::switchContact($contact['id'], $receiver, $actor);
 714                         }
 715                 }
 716         }
 717
 718         /**
 719          *
 720          *
 721          * @param       $object_data
 722          * @param array $activity
 723          *
 724          * @return mixed
 725          */
 726         private static function addActivityFields($object_data, $activity)
 727         {
 728                 if (!empty($activity['published']) && empty($object_data['published'])) {
 729                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
 730                 }
 731
 732                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
 733                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
 734                 }
 735
 736                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
 737                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
 738
 739                 if (!empty($object_data['object_id'])) {
 740                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
 741                         $objectId = Item::getURIByLink($object_data['object_id']);
 742                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
 743                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
 744                                 $object_data['object_id'] = $objectId;
 745                         }
 746                 }
 747
 748                 return $object_data;
 749         }
 750
 751         /**
 752          * Fetches the object data from external ressources if needed
 753          *
 754          * @param string  $object_id    Object ID of the the provided object
 755          * @param array   $object       The provided object array
 756          * @param boolean $trust_source Do we trust the provided object?
 757          * @param integer $uid          User ID for the signature that we use to fetch data
 758          *
 759          * @return array|false with trusted and valid object data
 760          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 761          * @throws \ImagickException
 762          */
 763         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
 764         {
 765                 // By fetching the type we check if the object is complete.
 766                 $type = JsonLD::fetchElement($object, '@type');
 767
 768                 if (!$trust_source || empty($type)) {
 769                         $data = ActivityPub::fetchContent($object_id, $uid);
 770                         if (!empty($data)) {
 771                                 $object = JsonLD::compact($data);
 772                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
 773                         } else {
 774                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
 775
 776                                 $item = Item::selectFirst([], ['uri' => $object_id]);
 777                                 if (!DBA::isResult($item)) {
 778                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
 779                                         return false;
 780                                 }
 781                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
 782                                 $data = ActivityPub\Transmitter::createNote($item);
 783                                 $object = JsonLD::compact($data);
 784                         }
 785                 } else {
 786                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
 787                 }
 788
 789                 $type = JsonLD::fetchElement($object, '@type');
 790
 791                 if (empty($type)) {
 792                         Logger::log('Empty type', Logger::DEBUG);
 793                         return false;
 794                 }
 795
 796                 if (in_array($type, self::CONTENT_TYPES)) {
 797                         $object_data = self::processObject($object);
 798
 799                         if (!empty($data)) {
 800                                 $object_data['raw'] = json_encode($data);
 801                         }
 802                         return $object_data;
 803                 }
 804
 805                 if ($type == 'as:Announce') {
 806                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
 807                         if (empty($object_id) || !is_string($object_id)) {
 808                                 return false;
 809                         }
 810                         return self::fetchObject($object_id, [], false, $uid);
 811                 }
 812
 813                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
 814                 return false;
 815         }
 816
 817         /**
 818          * Convert tags from JSON-LD format into a simplified format
 819          *
 820          * @param array $tags Tags in JSON-LD format
 821          *
 822          * @return array with tags in a simplified format
 823          */
 824         private static function processTags($tags)
 825         {
 826                 $taglist = [];
 827
 828                 if (empty($tags)) {
 829                         return [];
 830                 }
 831
 832                 foreach ($tags as $tag) {
 833                         if (empty($tag)) {
 834                                 continue;
 835                         }
 836
 837                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
 838                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
 839                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
 840
 841                         if (empty($element['type'])) {
 842                                 continue;
 843                         }
 844
 845                         if (empty($element['href'])) {
 846                                 $element['href'] = $element['name'];
 847                         }
 848
 849                         $taglist[] = $element;
 850                 }
 851                 return $taglist;
 852         }
 853
 854         /**
 855          * Convert emojis from JSON-LD format into a simplified format
 856          *
 857          * @param $emojis
 858          * @return array with emojis in a simplified format
 859          */
 860         private static function processEmojis($emojis)
 861         {
 862                 $emojilist = [];
 863
 864                 if (empty($emojis)) {
 865                         return [];
 866                 }
 867
 868                 foreach ($emojis as $emoji) {
 869                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
 870                                 continue;
 871                         }
 872
 873                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
 874                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
 875                                 'href' => $url];
 876
 877                         $emojilist[] = $element;
 878                 }
 879                 return $emojilist;
 880         }
 881
 882         /**
 883          * Convert attachments from JSON-LD format into a simplified format
 884          *
 885          * @param array $attachments Attachments in JSON-LD format
 886          *
 887          * @return array with attachmants in a simplified format
 888          */
 889         private static function processAttachments($attachments)
 890         {
 891                 $attachlist = [];
 892
 893                 if (empty($attachments)) {
 894                         return [];
 895                 }
 896
 897                 foreach ($attachments as $attachment) {
 898                         if (empty($attachment)) {
 899                                 continue;
 900                         }
 901
 902                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
 903                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
 904                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
 905                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')];
 906                 }
 907                 return $attachlist;
 908         }
 909
 910         /**
 911          * Fetch the original source or content with the "language" Markdown or HTML
 912          *
 913          * @param array $object
 914          * @param array $object_data
 915          *
 916          * @return array
 917          * @throws \Exception
 918          */
 919         private static function getSource($object, $object_data)
 920         {
 921                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
 922                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 923                 if (!empty($object_data['source'])) {
 924                         return $object_data;
 925                 }
 926
 927                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
 928                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 929                 if (!empty($object_data['source'])) {
 930                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
 931                         return $object_data;
 932                 }
 933
 934                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
 935                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
 936                 if (!empty($object_data['source'])) {
 937                         $object_data['source'] = HTML::toBBCode($object_data['source']);
 938                         return $object_data;
 939                 }
 940
 941                 return $object_data;
 942         }
 943
 944         /**
 945          * Check if the "as:url" element is an array with multiple links
 946          * This is the case with audio and video posts.
 947          * Then the links are added as attachments
 948          *
 949          * @param array $object      The raw object
 950          * @param array $object_data The parsed object data for later processing
 951          * @return array the object data
 952          */
 953         private static function processAttachmentUrls(array $object, array $object_data) {
 954                 // Check if this is some url with multiple links
 955                 if (empty($object['as:url'])) {
 956                         return $object_data;
 957                 }
 958
 959                 $urls = $object['as:url'];
 960                 $keys = array_keys($urls);
 961                 if (!is_numeric(array_pop($keys))) {
 962                         return $object_data;
 963                 }
 964
 965                 $attachments = [];
 966
 967                 foreach ($urls as $url) {
 968                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
 969                                 continue;
 970                         }
 971
 972                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
 973                         if (empty($href)) {
 974                                 continue;
 975                         }
 976
 977                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
 978                         if (empty($mediatype)) {
 979                                 continue;
 980                         }
 981
 982                         if ($mediatype == 'text/html') {
 983                                 $object_data['alternate-url'] = $href;
 984                         }
 985
 986                         $filetype = strtolower(substr($mediatype, 0, strpos($mediatype, '/')));
 987
 988                         if ($filetype == 'audio') {
 989                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href];
 990                         } elseif ($filetype == 'video') {
 991                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
 992
 993                                 // We save bandwidth by using a moderate height
 994                                 // Peertube normally uses these heights: 240, 360, 480, 720, 1080
 995                                 if (!empty($attachments[$filetype]['height']) &&
 996                                         (($height > 480) || $height < $attachments[$filetype]['height'])) {
 997                                         continue;
 998                                 }
 999
1000                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href, 'height' => $height];
1001                         }
1002                 }
1003
1004                 foreach ($attachments as $type => $attachment) {
1005                         $object_data['attachments'][] = ['type' => $type,
1006                                 'mediaType' => $attachment['type'],
1007                                 'name' => '',
1008                                 'url' => $attachment['url']];
1009                 }
1010                 return $object_data;
1011         }
1012
1013         /**
1014          * Fetches data from the object part of an activity
1015          *
1016          * @param array $object
1017          *
1018          * @return array
1019          * @throws \Exception
1020          */
1021         private static function processObject($object)
1022         {
1023                 if (!JsonLD::fetchElement($object, '@id')) {
1024                         return false;
1025                 }
1026
1027                 $object_data = [];
1028                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
1029                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
1030                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
1031
1032                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
1033                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
1034                         $object_data['reply-to-id'] = $object_data['id'];
1035                 } else {
1036                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
1037                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
1038                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
1039                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
1040                                 $object_data['reply-to-id'] = $replyToId;
1041                         }
1042                 }
1043
1044                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
1045                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
1046
1047                 if (empty($object_data['updated'])) {
1048                         $object_data['updated'] = $object_data['published'];
1049                 }
1050
1051                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
1052                         $object_data['published'] = $object_data['updated'];
1053                 }
1054
1055                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
1056                 if (empty($actor)) {
1057                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
1058                 }
1059
1060                 $location = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
1061                 $location = JsonLD::fetchElement($location, 'location', '@value');
1062                 if ($location) {
1063                         // Some AP software allow formatted text in post location, so we run all the text converters we have to boil
1064                         // down to HTML and then finally format to plaintext.
1065                         $location = Markdown::convert($location);
1066                         $location = BBCode::convert($location);
1067                         $location = HTML::toPlaintext($location);
1068                 }
1069
1070                 $object_data['sc:identifier'] = JsonLD::fetchElement($object, 'sc:identifier', '@value');
1071                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
1072                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
1073                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
1074                 $object_data['actor'] = $object_data['author'] = $actor;
1075                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
1076                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
1077                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
1078                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
1079                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
1080                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
1081                 $object_data = self::getSource($object, $object_data);
1082                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
1083                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
1084                 $object_data['location'] = $location;
1085                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
1086                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
1087                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
1088                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
1089                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
1090                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
1091                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji'));
1092                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
1093                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
1094                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
1095
1096                 // Special treatment for Hubzilla links
1097                 if (is_array($object_data['alternate-url'])) {
1098                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
1099
1100                         if (!is_string($object_data['alternate-url'])) {
1101                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1102                         }
1103                 }
1104
1105                 if (in_array($object_data['object_type'], ['as:Audio', 'as:Video'])) {
1106                         $object_data = self::processAttachmentUrls($object, $object_data);
1107                 }
1108
1109                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1110                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1111                 unset($object_data['receiver']['uid:-1']);
1112
1113                 // Common object data:
1114
1115                 // Unhandled
1116                 // @context, type, actor, signature, mediaType, duration, replies, icon
1117
1118                 // Also missing: (Defined in the standard, but currently unused)
1119                 // audience, preview, endTime, startTime, image
1120
1121                 // Data in Notes:
1122
1123                 // Unhandled
1124                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1125                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1126
1127                 // Data in video:
1128
1129                 // To-Do?
1130                 // category, licence, language, commentsEnabled
1131
1132                 // Unhandled
1133                 // views, waitTranscoding, state, support, subtitleLanguage
1134                 // likes, dislikes, shares, comments
1135
1136                 return $object_data;
1137         }
1138 }