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