src/Protocol/ActivityPub.php

   1 <?php
   2 /**
   3  * @file src/Protocol/ActivityPub.php
   4  */
   5 namespace Friendica\Protocol;
   6
   7 use Friendica\Database\DBA;
   8 use Friendica\Core\System;
   9 use Friendica\BaseObject;
  10 use Friendica\Util\Network;
  11 use Friendica\Util\HTTPSignature;
  12 use Friendica\Core\Protocol;
  13 use Friendica\Model\Conversation;
  14 use Friendica\Model\Contact;
  15 use Friendica\Model\Item;
  16 use Friendica\Model\Term;
  17 use Friendica\Model\User;
  18 use Friendica\Util\DateTimeFormat;
  19 use Friendica\Util\Crypto;
  20 use Friendica\Content\Text\BBCode;
  21 use Friendica\Content\Text\HTML;
  22 use Friendica\Core\Cache;
  23 use digitalbazaar\jsonld;
  24
  25 /**
  26  * @brief ActivityPub Protocol class
  27  * The ActivityPub Protocol is a message exchange protocol defined by the W3C.
  28  * https://www.w3.org/TR/activitypub/
  29  * https://www.w3.org/TR/activitystreams-core/
  30  * https://www.w3.org/TR/activitystreams-vocabulary/
  31  *
  32  * https://blog.joinmastodon.org/2018/06/how-to-implement-a-basic-activitypub-server/
  33  * https://blog.joinmastodon.org/2018/07/how-to-make-friends-and-verify-requests/
  34  *
  35  * Digest: https://tools.ietf.org/html/rfc5843
  36  * https://tools.ietf.org/html/draft-cavage-http-signatures-10#ref-15
  37  * https://github.com/digitalbazaar/php-json-ld
  38  *
  39  * Part of the code for HTTP signing is taken from the Osada project.
  40  * https://framagit.org/macgirvin/osada
  41  *
  42  * To-do:
  43  *
  44  * Receiver:
  45  * - Activities: Dislike, Update, Delete
  46  * - Object Types: Person, Tombstome
  47  *
  48  * Transmitter:
  49  * - Activities: Like, Dislike, Update, Delete
  50  * - Object Tyoes: Article, Announce, Person, Tombstone
  51  *
  52  * General:
  53  * - Message distribution
  54  * - Endpoints: Outbox, Object, Follower, Following
  55  * - General cleanup
  56  */
  57 class ActivityPub
  58 {
  59         const PUBLIC = 'https://www.w3.org/ns/activitystreams#Public';
  60
  61 public static function jsonld_document_loader($url)
  62 {
  63         $recursion = 0;
  64
  65         $x = debug_backtrace();
  66         if ($x) {
  67                 foreach ($x as $n) {
  68                         if ($n['function'] === __FUNCTION__)  {
  69                                 $recursion ++;
  70                         }
  71                 }
  72         }
  73
  74         if ($recursion > 5) {
  75                 logger('jsonld bomb detected at: ' . $url);
  76                 exit();
  77         }
  78
  79         $result = Cache::get('jsonld_document_loader:' . $url);
  80         if (!is_null($result)) {
  81                 return $result;
  82         }
  83
  84         $data = jsonld_default_document_loader($url);
  85         Cache::set('jsonld_document_loader:' . $url, $data, CACHE_DAY);
  86         return $data;
  87 }
  88
  89         public static function compactJsonLD($json)
  90         {
  91                 jsonld_set_document_loader('Friendica\Protocol\ActivityPub::jsonld_document_loader');
  92
  93                 $context = (object)['as' => 'https://www.w3.org/ns/activitystreams',
  94                         'w3sec' => 'https://w3id.org/security',
  95                         'ostatus' => (object)['@id' => 'http://ostatus.org#', '@type' => '@id'],
  96                         'vcard' => (object)['@id' => 'http://www.w3.org/2006/vcard/ns#', '@type' => '@id'],
  97                         'uuid' => (object)['@id' => 'http://schema.org/identifier', '@type' => '@id']];
  98
  99                 $jsonobj = json_decode(json_encode($json));
 100
 101                 $compacted = jsonld_compact($jsonobj, $context);
 102
 103                 return json_decode(json_encode($compacted), true);
 104         }
 105
 106         public static function isRequest()
 107         {
 108                 return stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json') ||
 109                         stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/ld+json');
 110         }
 111
 112         public static function transmit($data, $target, $uid)
 113         {
 114                 $owner = User::getOwnerDataById($uid);
 115
 116                 if (!$owner) {
 117                         return;
 118                 }
 119
 120                 $content = json_encode($data);
 121
 122                 // Header data that is about to be signed.
 123                 $host = parse_url($target, PHP_URL_HOST);
 124                 $path = parse_url($target, PHP_URL_PATH);
 125                 $digest = 'SHA-256=' . base64_encode(hash('sha256', $content, true));
 126                 $content_length = strlen($content);
 127
 128                 $headers = ['Content-Length: ' . $content_length, 'Digest: ' . $digest, 'Host: ' . $host];
 129
 130                 $signed_data = "(request-target): post " . $path . "\ncontent-length: " . $content_length . "\ndigest: " . $digest . "\nhost: " . $host;
 131
 132                 $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 133
 134                 $headers[] = 'Signature: keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) content-length digest host",signature="' . $signature . '"';
 135
 136                 $headers[] = 'Content-Type: application/activity+json';
 137
 138                 Network::post($target, $content, $headers);
 139                 $return_code = BaseObject::getApp()->get_curl_code();
 140
 141                 logger('Transmit to ' . $target . ' returned ' . $return_code);
 142         }
 143
 144         /**
 145          * Return the ActivityPub profile of the given user
 146          *
 147          * @param integer $uid User ID
 148          * @return array
 149          */
 150         public static function profile($uid)
 151         {
 152                 $accounttype = ['Person', 'Organization', 'Service', 'Group', 'Application', 'page-flags'];
 153                 $condition = ['uid' => $uid, 'blocked' => false, 'account_expired' => false,
 154                         'account_removed' => false, 'verified' => true];
 155                 $fields = ['guid', 'nickname', 'pubkey', 'account-type'];
 156                 $user = DBA::selectFirst('user', $fields, $condition);
 157                 if (!DBA::isResult($user)) {
 158                         return [];
 159                 }
 160
 161                 $fields = ['locality', 'region', 'country-name'];
 162                 $profile = DBA::selectFirst('profile', $fields, ['uid' => $uid, 'is-default' => true]);
 163                 if (!DBA::isResult($profile)) {
 164                         return [];
 165                 }
 166
 167                 $fields = ['name', 'url', 'location', 'about', 'avatar'];
 168                 $contact = DBA::selectFirst('contact', $fields, ['uid' => $uid, 'self' => true]);
 169                 if (!DBA::isResult($contact)) {
 170                         return [];
 171                 }
 172
 173                 $data = ['@context' => ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1',
 174                         ['vcard' => 'http://www.w3.org/2006/vcard/ns#', 'uuid' => 'http://schema.org/identifier',
 175                         'sensitive' => 'as:sensitive', 'manuallyApprovesFollowers' => 'as:manuallyApprovesFollowers']]];
 176
 177                 $data['id'] = $contact['url'];
 178                 $data['uuid'] = $user['guid'];
 179                 $data['type'] = $accounttype[$user['account-type']];
 180                 $data['following'] = System::baseUrl() . '/following/' . $user['nickname'];
 181                 $data['followers'] = System::baseUrl() . '/followers/' . $user['nickname'];
 182                 $data['inbox'] = System::baseUrl() . '/inbox/' . $user['nickname'];
 183                 $data['outbox'] = System::baseUrl() . '/outbox/' . $user['nickname'];
 184                 $data['preferredUsername'] = $user['nickname'];
 185                 $data['name'] = $contact['name'];
 186                 $data['vcard:hasAddress'] = ['@type' => 'vcard:Home', 'vcard:country-name' => $profile['country-name'],
 187                         'vcard:region' => $profile['region'], 'vcard:locality' => $profile['locality']];
 188                 $data['summary'] = $contact['about'];
 189                 $data['url'] = $contact['url'];
 190                 $data['manuallyApprovesFollowers'] = in_array($profile['page-flags'], [Contact::PAGE_NORMAL, Contact::PAGE_PRVGROUP]);
 191                 $data['publicKey'] = ['id' => $contact['url'] . '#main-key',
 192                         'owner' => $contact['url'],
 193                         'publicKeyPem' => $user['pubkey']];
 194                 $data['endpoints'] = ['sharedInbox' => System::baseUrl() . '/inbox'];
 195                 $data['icon'] = ['type' => 'Image',
 196                         'url' => $contact['avatar']];
 197
 198                 // tags: https://kitty.town/@inmysocks/100656097926961126.json
 199                 return $data;
 200         }
 201
 202         public static function createPermissionBlockForItem($item)
 203         {
 204                 $data = ['to' => [], 'cc' => []];
 205
 206                 $terms = Term::tagArrayFromItemId($item['id']);
 207
 208                 if (!$item['private']) {
 209                         $data['to'][] = self::PUBLIC;
 210                         $data['cc'][] = System::baseUrl() . '/followers/' . $item['author-nick'];
 211
 212                         foreach ($terms as $term) {
 213                                 if ($term['type'] != TERM_MENTION) {
 214                                         continue;
 215                                 }
 216                                 $profile = self::fetchprofile($term['url']);
 217                                 if (!empty($profile)) {
 218                                         $data['cc'][] = $profile['url'];
 219                                 }
 220                         }
 221                 } else {
 222                         //$data['cc'][] = System::baseUrl() . '/followers/' . $item['author-nick'];
 223                         $receiver_list = Item::enumeratePermissions($item);
 224
 225                         $mentioned = [];
 226
 227                         foreach ($terms as $term) {
 228                                 if ($term['type'] != TERM_MENTION) {
 229                                         continue;
 230                                 }
 231                                 $cid = Contact::getIdForURL($term['url'], $item['uid']);
 232                                 if (!empty($cid) && in_array($cid, $receiver_list)) {
 233                                         $contact = DBA::selectFirst('contact', ['url'], ['id' => $cid, 'network' => Protocol::ACTIVITYPUB]);
 234                                         $data['to'][] = $contact['url'];
 235                                 }
 236                         }
 237
 238                         foreach ($receiver_list as $receiver) {
 239                                 $contact = DBA::selectFirst('contact', ['url'], ['id' => $receiver, 'network' => Protocol::ACTIVITYPUB]);
 240                                 $data['cc'][] = $contact['url'];
 241                         }
 242
 243                         if (empty($data['to'])) {
 244                                 $data['to'] = $data['cc'];
 245                                 $data['cc'] = [];
 246                         }
 247                 }
 248
 249                 return $data;
 250         }
 251
 252         public static function fetchTargetInboxes($item)
 253         {
 254                 $inboxes = [];
 255
 256                 $terms = Term::tagArrayFromItemId($item['id']);
 257                 if (!$item['private']) {
 258                         $contacts = DBA::select('contact', ['notify', 'batch'], ['uid' => $item['uid'],
 259                                         'rel' => [Contact::FOLLOWER, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB]);
 260                         while ($contact = DBA::fetch($contacts)) {
 261                                 $contact = defaults($contact, 'batch', $contact['notify']);
 262                                 $inboxes[$contact] = $contact;
 263                         }
 264                         DBA::close($contacts);
 265
 266                         foreach ($terms as $term) {
 267                                 if ($term['type'] != TERM_MENTION) {
 268                                         continue;
 269                                 }
 270                                 $profile = self::fetchprofile($term['url']);
 271                                 if (!empty($profile)) {
 272                                         $target = defaults($profile, 'sharedinbox', $profile['inbox']);
 273                                         $inboxes[$target] = $target;
 274                                 }
 275                         }
 276                 } else {
 277                         $receiver_list = Item::enumeratePermissions($item);
 278
 279                         $mentioned = [];
 280
 281                         foreach ($terms as $term) {
 282                                 if ($term['type'] != TERM_MENTION) {
 283                                         continue;
 284                                 }
 285                                 $cid = Contact::getIdForURL($term['url'], $item['uid']);
 286                                 if (!empty($cid) && in_array($cid, $receiver_list)) {
 287                                         $contact = DBA::selectFirst('contact', ['url'], ['id' => $cid, 'network' => Protocol::ACTIVITYPUB]);
 288                                         $profile = self::fetchprofile($contact['url']);
 289                                         if (!empty($profile['network'])) {
 290                                                 $target = defaults($profile, 'sharedinbox', $profile['inbox']);
 291                                                 $inboxes[$target] = $target;
 292                                         }
 293                                 }
 294                         }
 295
 296                         foreach ($receiver_list as $receiver) {
 297                                 $contact = DBA::selectFirst('contact', ['url'], ['id' => $receiver, 'network' => Protocol::ACTIVITYPUB]);
 298                                 $profile = self::fetchprofile($contact['url']);
 299                                 if (!empty($profile['network'])) {
 300                                         $target = defaults($profile, 'sharedinbox', $profile['inbox']);
 301                                         $inboxes[$target] = $target;
 302                                 }
 303                         }
 304                 }
 305
 306                 $profile = self::fetchprofile($item['author-link']);
 307                 if (!empty($profile['sharedinbox'])) {
 308                         unset($inboxes[$profile['sharedinbox']]);
 309                 }
 310
 311                 if (!empty($profile['inbox'])) {
 312                         unset($inboxes[$profile['inbox']]);
 313                 }
 314
 315                 return $inboxes;
 316         }
 317
 318         public static function createActivityFromItem($item_id)
 319         {
 320                 $item = Item::selectFirst([], ['id' => $item_id]);
 321
 322                 if (!DBA::isResult($item)) {
 323                         return false;
 324                 }
 325
 326                 $condition = ['item-uri' => $item['uri'], 'protocol' => Conversation::PARCEL_ACTIVITYPUB];
 327                 $conversation = DBA::selectFirst('conversation', ['source'], $condition);
 328                 if (DBA::isResult($conversation)) {
 329                         $data = json_decode($conversation['source']);
 330                         if (!empty($data)) {
 331                                 return $data;
 332                         }
 333                 }
 334
 335                 $data = ['@context' => ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1',
 336                         ['ostatus' => 'http://ostatus.org#', 'sensitive' => 'as:sensitive',
 337                         'Hashtag' => 'as:Hashtag', 'atomUri' => 'ostatus:atomUri',
 338                         'conversation' => 'ostatus:conversation',
 339                         'inReplyToAtomUri' => 'ostatus:inReplyToAtomUri']]];
 340
 341                 $data['type'] = 'Create';
 342                 $data['id'] = $item['uri'] . '#activity';
 343                 $data['actor'] = $item['author-link'];
 344
 345                 $data['published'] = DateTimeFormat::utc($item["created"]."+00:00", DateTimeFormat::ATOM);
 346
 347                 if ($item["created"] != $item["edited"]) {
 348                         $data['updated'] = DateTimeFormat::utc($item["edited"]."+00:00", DateTimeFormat::ATOM);
 349                 }
 350
 351                 $data = array_merge($data, ActivityPub::createPermissionBlockForItem($item));
 352
 353                 $data['object'] = self::createNote($item);
 354                 return $data;
 355         }
 356
 357         public static function createObjectFromItemID($item_id)
 358         {
 359                 $item = Item::selectFirst([], ['id' => $item_id]);
 360
 361                 if (!DBA::isResult($item)) {
 362                         return false;
 363                 }
 364
 365                 $data = ['@context' => ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1',
 366                         ['ostatus' => 'http://ostatus.org#', 'sensitive' => 'as:sensitive',
 367                         'Hashtag' => 'as:Hashtag', 'atomUri' => 'ostatus:atomUri',
 368                         'conversation' => 'ostatus:conversation',
 369                         'inReplyToAtomUri' => 'ostatus:inReplyToAtomUri']]];
 370
 371                 $data = array_merge($data, self::createNote($item));
 372
 373
 374                 return $data;
 375         }
 376
 377         private static function createTagList($item)
 378         {
 379                 $tags = [];
 380
 381                 $terms = Term::tagArrayFromItemId($item['id']);
 382                 foreach ($terms as $term) {
 383                         if ($term['type'] == TERM_MENTION) {
 384                                 $contact = Contact::getDetailsByURL($term['url']);
 385                                 if (!empty($contact['addr'])) {
 386                                         $mention = '@' . $contact['addr'];
 387                                 } else {
 388                                         $mention = '@' . $term['url'];
 389                                 }
 390
 391                                 $tags[] = ['type' => 'Mention', 'href' => $term['url'], 'name' => $mention];
 392                         }
 393                 }
 394
 395                 return $tags;
 396         }
 397
 398         public static function createNote($item)
 399         {
 400                 $data = [];
 401                 $data['type'] = 'Note';
 402                 $data['id'] = $item['uri'];
 403
 404                 if ($item['uri'] != $item['thr-parent']) {
 405                         $data['inReplyTo'] = $item['thr-parent'];
 406                 }
 407
 408                 $conversation = DBA::selectFirst('conversation', ['conversation-uri'], ['item-uri' => $item['parent-uri']]);
 409                 if (DBA::isResult($conversation) && !empty($conversation['conversation-uri'])) {
 410                         $conversation_uri = $conversation['conversation-uri'];
 411                 } else {
 412                         $conversation_uri = $item['parent-uri'];
 413                 }
 414
 415                 $data['context'] = $data['conversation'] = $conversation_uri;
 416                 $data['actor'] = $item['author-link'];
 417                 $data = array_merge($data, ActivityPub::createPermissionBlockForItem($item));
 418                 $data['published'] = DateTimeFormat::utc($item["created"]."+00:00", DateTimeFormat::ATOM);
 419
 420                 if ($item["created"] != $item["edited"]) {
 421                         $data['updated'] = DateTimeFormat::utc($item["edited"]."+00:00", DateTimeFormat::ATOM);
 422                 }
 423
 424                 $data['attributedTo'] = $item['author-link'];
 425                 $data['name'] = BBCode::convert($item['title'], false, 7);
 426                 $data['content'] = BBCode::convert($item['body'], false, 7);
 427                 $data['source'] = ['content' => $item['body'], 'mediaType' => "text/bbcode"];
 428                 $data['summary'] = ''; // Ignore by now
 429                 $data['sensitive'] = false; // - Query NSFW
 430                 //$data['emoji'] = []; // Ignore by now
 431                 $data['tag'] = self::createTagList($item);
 432                 $data['attachment'] = []; // @ToDo
 433                 return $data;
 434         }
 435
 436         public static function transmitActivity($activity, $target, $uid)
 437         {
 438                 $profile = self::fetchprofile($target);
 439
 440                 $owner = User::getOwnerDataById($uid);
 441
 442                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 443                         'id' => System::baseUrl() . '/activity/' . System::createGUID(),
 444                         'type' => $activity,
 445                         'actor' => $owner['url'],
 446                         'object' => $profile['url'],
 447                         'to' => $profile['url']];
 448
 449                 logger('Sending activity ' . $activity . ' to ' . $target . ' for user ' . $uid, LOGGER_DEBUG);
 450                 return self::transmit($data,  $profile['inbox'], $uid);
 451         }
 452
 453         public static function transmitContactAccept($target, $id, $uid)
 454         {
 455                 $profile = self::fetchprofile($target);
 456
 457                 $owner = User::getOwnerDataById($uid);
 458                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 459                         'id' => System::baseUrl() . '/activity/' . System::createGUID(),
 460                         'type' => 'Accept',
 461                         'actor' => $owner['url'],
 462                         'object' => ['id' => $id, 'type' => 'Follow',
 463                                 'actor' => $profile['url'],
 464                                 'object' => $owner['url']],
 465                         'to' => $profile['url']];
 466
 467                 logger('Sending accept to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 468                 return self::transmit($data,  $profile['inbox'], $uid);
 469         }
 470
 471         public static function transmitContactReject($target, $id, $uid)
 472         {
 473                 $profile = self::fetchprofile($target);
 474
 475                 $owner = User::getOwnerDataById($uid);
 476                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 477                         'id' => System::baseUrl() . '/activity/' . System::createGUID(),
 478                         'type' => 'Reject',
 479                         'actor' => $owner['url'],
 480                         'object' => ['id' => $id, 'type' => 'Follow',
 481                                 'actor' => $profile['url'],
 482                                 'object' => $owner['url']],
 483                         'to' => $profile['url']];
 484
 485                 logger('Sending reject to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 486                 return self::transmit($data,  $profile['inbox'], $uid);
 487         }
 488
 489         public static function transmitContactUndo($target, $uid)
 490         {
 491                 $profile = self::fetchprofile($target);
 492
 493                 $id = System::baseUrl() . '/activity/' . System::createGUID();
 494
 495                 $owner = User::getOwnerDataById($uid);
 496                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 497                         'id' => $id,
 498                         'type' => 'Undo',
 499                         'actor' => $owner['url'],
 500                         'object' => ['id' => $id, 'type' => 'Follow',
 501                                 'actor' => $owner['url'],
 502                                 'object' => $profile['url']],
 503                         'to' => $profile['url']];
 504
 505                 logger('Sending undo to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 506                 return self::transmit($data,  $profile['inbox'], $uid);
 507         }
 508
 509         /**
 510          * Fetches ActivityPub content from the given url
 511          *
 512          * @param string $url content url
 513          * @return array
 514          */
 515         public static function fetchContent($url)
 516         {
 517                 $ret = Network::curl($url, false, $redirects, ['accept_content' => 'application/activity+json, application/ld+json']);
 518                 if (!$ret['success'] || empty($ret['body'])) {
 519                         return;
 520                 }
 521
 522                 return json_decode($ret['body'], true);
 523         }
 524
 525         /**
 526          * Resolves the profile url from the address by using webfinger
 527          *
 528          * @param string $addr profile address (user@domain.tld)
 529          * @return string url
 530          */
 531         private static function addrToUrl($addr)
 532         {
 533                 $addr_parts = explode('@', $addr);
 534                 if (count($addr_parts) != 2) {
 535                         return false;
 536                 }
 537
 538                 $webfinger = 'https://' . $addr_parts[1] . '/.well-known/webfinger?resource=acct:' . urlencode($addr);
 539
 540                 $ret = Network::curl($webfinger, false, $redirects, ['accept_content' => 'application/jrd+json,application/json']);
 541                 if (!$ret['success'] || empty($ret['body'])) {
 542                         return false;
 543                 }
 544
 545                 $data = json_decode($ret['body'], true);
 546
 547                 if (empty($data['links'])) {
 548                         return false;
 549                 }
 550
 551                 foreach ($data['links'] as $link) {
 552                         if (empty($link['href']) || empty($link['rel']) || empty($link['type'])) {
 553                                 continue;
 554                         }
 555
 556                         if (($link['rel'] == 'self') && ($link['type'] == 'application/activity+json')) {
 557                                 return $link['href'];
 558                         }
 559                 }
 560
 561                 return false;
 562         }
 563
 564         public static function verifySignature($content, $http_headers)
 565         {
 566                 $object = json_decode($content, true);
 567
 568                 if (empty($object)) {
 569                         return false;
 570                 }
 571
 572                 $actor = self::processElement($object, 'actor', 'id');
 573
 574                 $headers = [];
 575                 $headers['(request-target)'] = strtolower($http_headers['REQUEST_METHOD']) . ' ' . $http_headers['REQUEST_URI'];
 576
 577                 // First take every header
 578                 foreach ($http_headers as $k => $v) {
 579                         $field = str_replace('_', '-', strtolower($k));
 580                         $headers[$field] = $v;
 581                 }
 582
 583                 // Now add every http header
 584                 foreach ($http_headers as $k => $v) {
 585                         if (strpos($k, 'HTTP_') === 0) {
 586                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
 587                                 $headers[$field] = $v;
 588                         }
 589                 }
 590
 591                 $sig_block = ActivityPub::parseSigHeader($http_headers['HTTP_SIGNATURE']);
 592
 593                 if (empty($sig_block) || empty($sig_block['headers']) || empty($sig_block['keyId'])) {
 594                         return false;
 595                 }
 596
 597                 $signed_data = '';
 598                 foreach ($sig_block['headers'] as $h) {
 599                         if (array_key_exists($h, $headers)) {
 600                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
 601                         }
 602                 }
 603                 $signed_data = rtrim($signed_data, "\n");
 604
 605                 if (empty($signed_data)) {
 606                         return false;
 607                 }
 608
 609                 $algorithm = null;
 610
 611                 if ($sig_block['algorithm'] === 'rsa-sha256') {
 612                         $algorithm = 'sha256';
 613                 }
 614
 615                 if ($sig_block['algorithm'] === 'rsa-sha512') {
 616                         $algorithm = 'sha512';
 617                 }
 618
 619                 if (empty($algorithm)) {
 620                         return false;
 621                 }
 622
 623                 $key = self::fetchKey($sig_block['keyId'], $actor);
 624
 625                 if (empty($key)) {
 626                         return false;
 627                 }
 628
 629                 if (!Crypto::rsaVerify($signed_data, $sig_block['signature'], $key, $algorithm)) {
 630                         return false;
 631                 }
 632
 633                 // Check the digest when it is part of the signed data
 634                 if (in_array('digest', $sig_block['headers'])) {
 635                         $digest = explode('=', $headers['digest'], 2);
 636                         if ($digest[0] === 'SHA-256') {
 637                                 $hashalg = 'sha256';
 638                         }
 639                         if ($digest[0] === 'SHA-512') {
 640                                 $hashalg = 'sha512';
 641                         }
 642
 643                         /// @todo add all hashes from the rfc
 644
 645                         if (!empty($hashalg) && base64_encode(hash($hashalg, $content, true)) != $digest[1]) {
 646                                 return false;
 647                         }
 648                 }
 649
 650                 // Check the content-length when it is part of the signed data
 651                 if (in_array('content-length', $sig_block['headers'])) {
 652                         if (strlen($content) != $headers['content-length']) {
 653                                 return false;
 654                         }
 655                 }
 656
 657                 return true;
 658
 659         }
 660
 661         private static function fetchKey($id, $actor)
 662         {
 663                 $url = (strpos($id, '#') ? substr($id, 0, strpos($id, '#')) : $id);
 664
 665                 $profile = self::fetchprofile($url);
 666                 if (!empty($profile)) {
 667                         return $profile['pubkey'];
 668                 } elseif ($url != $actor) {
 669                         $profile = self::fetchprofile($actor);
 670                         if (!empty($profile)) {
 671                                 return $profile['pubkey'];
 672                         }
 673                 }
 674
 675                 return false;
 676         }
 677
 678         /**
 679          * @brief
 680          *
 681          * @param string $header
 682          * @return array associate array with
 683          *   - \e string \b keyID
 684          *   - \e string \b algorithm
 685          *   - \e array  \b headers
 686          *   - \e string \b signature
 687          */
 688         private static function parseSigHeader($header)
 689         {
 690                 $ret = [];
 691                 $matches = [];
 692
 693                 if (preg_match('/keyId="(.*?)"/ism',$header,$matches)) {
 694                         $ret['keyId'] = $matches[1];
 695                 }
 696
 697                 if (preg_match('/algorithm="(.*?)"/ism',$header,$matches)) {
 698                         $ret['algorithm'] = $matches[1];
 699                 }
 700
 701                 if (preg_match('/headers="(.*?)"/ism',$header,$matches)) {
 702                         $ret['headers'] = explode(' ', $matches[1]);
 703                 }
 704
 705                 if (preg_match('/signature="(.*?)"/ism',$header,$matches)) {
 706                         $ret['signature'] = base64_decode(preg_replace('/\s+/','',$matches[1]));
 707                 }
 708
 709                 return $ret;
 710         }
 711
 712         public static function fetchprofile($url, $update = false)
 713         {
 714                 if (empty($url)) {
 715                         return false;
 716                 }
 717
 718                 if (!$update) {
 719                         $apcontact = DBA::selectFirst('apcontact', [], ['url' => $url]);
 720                         if (DBA::isResult($apcontact)) {
 721                                 return $apcontact;
 722                         }
 723
 724                         $apcontact = DBA::selectFirst('apcontact', [], ['alias' => $url]);
 725                         if (DBA::isResult($apcontact)) {
 726                                 return $apcontact;
 727                         }
 728
 729                         $apcontact = DBA::selectFirst('apcontact', [], ['addr' => $url]);
 730                         if (DBA::isResult($apcontact)) {
 731                                 return $apcontact;
 732                         }
 733                 }
 734
 735                 if (empty(parse_url($url, PHP_URL_SCHEME))) {
 736                         $url = self::addrToUrl($url);
 737                         if (empty($url)) {
 738                                 return false;
 739                         }
 740                 }
 741
 742                 $data = self::fetchContent($url);
 743
 744                 if (empty($data) || empty($data['id']) || empty($data['inbox'])) {
 745                         return false;
 746                 }
 747
 748                 $apcontact = [];
 749                 $apcontact['url'] = $data['id'];
 750                 $apcontact['uuid'] = defaults($data, 'uuid', null);
 751                 $apcontact['type'] = defaults($data, 'type', null);
 752                 $apcontact['following'] = defaults($data, 'following', null);
 753                 $apcontact['followers'] = defaults($data, 'followers', null);
 754                 $apcontact['inbox'] = defaults($data, 'inbox', null);
 755                 $apcontact['outbox'] = defaults($data, 'outbox', null);
 756                 $apcontact['sharedinbox'] = self::processElement($data, 'endpoints', 'sharedInbox');
 757                 $apcontact['nick'] = defaults($data, 'preferredUsername', null);
 758                 $apcontact['name'] = defaults($data, 'name', $apcontact['nick']);
 759                 $apcontact['about'] = defaults($data, 'summary', '');
 760                 $apcontact['photo'] = self::processElement($data, 'icon', 'url');
 761                 $apcontact['alias'] = self::processElement($data, 'url', 'href');
 762
 763                 $parts = parse_url($apcontact['url']);
 764                 unset($parts['scheme']);
 765                 unset($parts['path']);
 766                 $apcontact['addr'] = $apcontact['nick'] . '@' . str_replace('//', '', Network::unparseURL($parts));
 767
 768                 $apcontact['pubkey'] = trim(self::processElement($data, 'publicKey', 'publicKeyPem'));
 769
 770                 // To-Do
 771                 // manuallyApprovesFollowers
 772
 773                 // Unhandled
 774                 // @context, tag, attachment, image, nomadicLocations, signature, following, followers, featured, movedTo, liked
 775
 776                 // Unhandled from Misskey
 777                 // sharedInbox, isCat
 778
 779                 // Unhandled from Kroeg
 780                 // kroeg:blocks, updated
 781
 782                 // Check if the address is resolvable
 783                 if (self::addrToUrl($apcontact['addr']) == $apcontact['url']) {
 784                         $parts = parse_url($apcontact['url']);
 785                         unset($parts['path']);
 786                         $apcontact['baseurl'] = Network::unparseURL($parts);
 787                 } else {
 788                         $apcontact['addr'] = null;
 789                 }
 790
 791                 if ($apcontact['url'] == $apcontact['alias']) {
 792                         $apcontact['alias'] = null;
 793                 }
 794
 795                 $apcontact['updated'] = DateTimeFormat::utcNow();
 796
 797                 DBA::update('apcontact', $apcontact, ['url' => $url], true);
 798
 799                 return $apcontact;
 800         }
 801
 802         /**
 803          * Fetches a profile from the given url into an array that is compatible to Probe::uri
 804          *
 805          * @param string $url profile url
 806          * @return array
 807          */
 808         public static function probeProfile($url)
 809         {
 810                 $apcontact = self::fetchprofile($url, true);
 811                 if (empty($apcontact)) {
 812                         return false;
 813                 }
 814
 815                 $profile = ['network' => Protocol::ACTIVITYPUB];
 816                 $profile['nick'] = $apcontact['nick'];
 817                 $profile['name'] = $apcontact['name'];
 818                 $profile['guid'] = $apcontact['uuid'];
 819                 $profile['url'] = $apcontact['url'];
 820                 $profile['addr'] = $apcontact['addr'];
 821                 $profile['alias'] = $apcontact['alias'];
 822                 $profile['photo'] = $apcontact['photo'];
 823                 // $profile['community']
 824                 // $profile['keywords']
 825                 // $profile['location']
 826                 $profile['about'] = $apcontact['about'];
 827                 $profile['batch'] = $apcontact['sharedinbox'];
 828                 $profile['notify'] = $apcontact['inbox'];
 829                 $profile['poll'] = $apcontact['outbox'];
 830                 $profile['pubkey'] = $apcontact['pubkey'];
 831                 $profile['baseurl'] = $apcontact['baseurl'];
 832
 833                 // Remove all "null" fields
 834                 foreach ($profile as $field => $content) {
 835                         if (is_null($content)) {
 836                                 unset($profile[$field]);
 837                         }
 838                 }
 839
 840                 return $profile;
 841         }
 842
 843         public static function processInbox($body, $header, $uid)
 844         {
 845                 logger('Incoming message for user ' . $uid, LOGGER_DEBUG);
 846
 847                 if (!self::verifySignature($body, $header)) {
 848                         logger('Invalid signature, message will be discarded.', LOGGER_DEBUG);
 849                         return;
 850                 }
 851
 852                 $activity = json_decode($body, true);
 853
 854                 if (!is_array($activity)) {
 855                         logger('Invalid body.', LOGGER_DEBUG);
 856                         return;
 857                 }
 858
 859                 self::processActivity($activity, $body, $uid);
 860         }
 861
 862         public static function fetchOutbox($url)
 863         {
 864                 $data = self::fetchContent($url);
 865                 if (empty($data)) {
 866                         return;
 867                 }
 868
 869                 if (!empty($data['orderedItems'])) {
 870                         $items = $data['orderedItems'];
 871                 } elseif (!empty($data['first']['orderedItems'])) {
 872                         $items = $data['first']['orderedItems'];
 873                 } elseif (!empty($data['first'])) {
 874                         self::fetchOutbox($data['first']);
 875                         return;
 876                 } else {
 877                         $items = [];
 878                 }
 879
 880                 foreach ($items as $activity) {
 881                         self::processActivity($activity);
 882                 }
 883         }
 884
 885         private static function prepareObjectData($activity, $uid)
 886         {
 887                 $actor = self::processElement($activity, 'actor', 'id');
 888                 if (empty($actor)) {
 889                         logger('Empty actor', LOGGER_DEBUG);
 890                         return [];
 891                 }
 892
 893                 // Fetch all receivers from to, cc, bto and bcc
 894                 $receivers = self::getReceivers($activity, $actor);
 895
 896                 // When it is a delivery to a personal inbox we add that user to the receivers
 897                 if (!empty($uid)) {
 898                         $owner = User::getOwnerDataById($uid);
 899                         $additional = ['uid:' . $uid => $uid];
 900                         $receivers = array_merge($receivers, $additional);
 901                 }
 902
 903                 logger('Receivers: ' . json_encode($receivers), LOGGER_DEBUG);
 904
 905                 $public = in_array(0, $receivers);
 906
 907                 if (is_string($activity['object'])) {
 908                         $object_url = $activity['object'];
 909                 } elseif (!empty($activity['object']['id'])) {
 910                         $object_url = $activity['object']['id'];
 911                 } else {
 912                         logger('No object found', LOGGER_DEBUG);
 913                         return [];
 914                 }
 915
 916                 // Fetch the content only on activities where this matters
 917                 if (in_array($activity['type'], ['Create', 'Update', 'Announce'])) {
 918                         $object_data = self::fetchObject($object_url, $activity['object']);
 919                         if (empty($object_data)) {
 920                                 logger("Object data couldn't be processed", LOGGER_DEBUG);
 921                                 return [];
 922                         }
 923                 } elseif ($activity['type'] == 'Accept') {
 924                         $object_data = [];
 925                         $object_data['object_type'] = self::processElement($activity, 'object', 'type');
 926                         $object_data['object'] = self::processElement($activity, 'object', 'actor');
 927                 } elseif ($activity['type'] == 'Undo') {
 928                         $object_data = [];
 929                         $object_data['object_type'] = self::processElement($activity, 'object', 'type');
 930                         $object_data['object'] = self::processElement($activity, 'object', 'object');
 931                 } elseif (in_array($activity['type'], ['Like', 'Dislike'])) {
 932                         // Create a mostly empty array out of the activity data (instead of the object).
 933                         // This way we later don't have to check for the existence of ech individual array element.
 934                         $object_data = self::processCommonData($activity);
 935                         $object_data['name'] = $activity['type'];
 936                         $object_data['author'] = $activity['actor'];
 937                         $object_data['object'] = $object_url;
 938                 } elseif ($activity['type'] == 'Follow') {
 939                         $object_data['id'] = $activity['id'];
 940                         $object_data['object'] = $object_url;
 941                 } else {
 942                         $object_data = [];
 943                 }
 944
 945                 $object_data = self::addActivityFields($object_data, $activity);
 946
 947                 $object_data['type'] = $activity['type'];
 948                 $object_data['owner'] = $actor;
 949                 $object_data['receiver'] = array_merge(defaults($object_data, 'receiver', []), $receivers);
 950
 951                 return $object_data;
 952         }
 953
 954         private static function processActivity($activity, $body = '', $uid = null)
 955         {
 956                 if (empty($activity['type'])) {
 957                         logger('Empty type', LOGGER_DEBUG);
 958                         return;
 959                 }
 960
 961                 if (empty($activity['object'])) {
 962                         logger('Empty object', LOGGER_DEBUG);
 963                         return;
 964                 }
 965
 966                 if (empty($activity['actor'])) {
 967                         logger('Empty actor', LOGGER_DEBUG);
 968                         return;
 969
 970                 }
 971
 972                 // Non standard
 973                 // title, atomUri, context_id, statusnetConversationId
 974
 975                 // To-Do?
 976                 // context, location, signature;
 977
 978                 logger('Processing activity: ' . $activity['type'], LOGGER_DEBUG);
 979
 980                 $object_data = self::prepareObjectData($activity, $uid);
 981                 if (empty($object_data)) {
 982                         logger('No object data found', LOGGER_DEBUG);
 983                         return;
 984                 }
 985
 986                 switch ($activity['type']) {
 987                         case 'Create':
 988                         case 'Announce':
 989                                 self::createItem($object_data, $body);
 990                                 break;
 991
 992                         case 'Like':
 993                                 self::likeItem($object_data, $body);
 994                                 break;
 995
 996                         case 'Dislike':
 997                                 break;
 998
 999                         case 'Update':
1000                                 break;
1001
1002                         case 'Delete':
1003                                 break;
1004
1005                         case 'Follow':
1006                                 self::followUser($object_data);
1007                                 break;
1008
1009                         case 'Accept':
1010                                 if ($object_data['object_type'] == 'Follow') {
1011                                         self::acceptFollowUser($object_data);
1012                                 }
1013                                 break;
1014
1015                         case 'Undo':
1016                                 if ($object_data['object_type'] == 'Follow') {
1017                                         self::undoFollowUser($object_data);
1018                                 }
1019                                 break;
1020
1021                         default:
1022                                 logger('Unknown activity: ' . $activity['type'], LOGGER_DEBUG);
1023                                 break;
1024                 }
1025         }
1026
1027         private static function getReceivers($activity, $actor)
1028         {
1029                 $receivers = [];
1030
1031                 if (!empty($actor)) {
1032                         $profile = self::fetchprofile($actor);
1033                         $followers = defaults($profile, 'followers', '');
1034
1035                         logger('Actor: ' . $actor . ' - Followers: ' . $followers, LOGGER_DEBUG);
1036                 } else {
1037                         logger('Empty actor', LOGGER_DEBUG);
1038                         $followers = '';
1039                 }
1040
1041                 $elements = ['to', 'cc', 'bto', 'bcc'];
1042                 foreach ($elements as $element) {
1043                         if (empty($activity[$element])) {
1044                                 continue;
1045                         }
1046
1047                         // The receiver can be an arror or a string
1048                         if (is_string($activity[$element])) {
1049                                 $activity[$element] = [$activity[$element]];
1050                         }
1051
1052                         foreach ($activity[$element] as $receiver) {
1053                                 if ($receiver == self::PUBLIC) {
1054                                         $receivers['uid:0'] = 0;
1055                                 }
1056
1057                                 if (($receiver == self::PUBLIC) && !empty($actor)) {
1058                                         // This will most likely catch all OStatus connections to Mastodon
1059                                         $condition = ['alias' => [$actor, normalise_link($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]];
1060                                         $contacts = DBA::select('contact', ['uid'], $condition);
1061                                         while ($contact = DBA::fetch($contacts)) {
1062                                                 if ($contact['uid'] != 0) {
1063                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
1064                                                 }
1065                                         }
1066                                         DBA::close($contacts);
1067                                 }
1068
1069                                 if (in_array($receiver, [$followers, self::PUBLIC]) && !empty($actor)) {
1070                                         $condition = ['nurl' => normalise_link($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
1071                                                 'network' => Protocol::ACTIVITYPUB];
1072                                         $contacts = DBA::select('contact', ['uid'], $condition);
1073                                         while ($contact = DBA::fetch($contacts)) {
1074                                                 if ($contact['uid'] != 0) {
1075                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
1076                                                 }
1077                                         }
1078                                         DBA::close($contacts);
1079                                         continue;
1080                                 }
1081
1082                                 $condition = ['self' => true, 'nurl' => normalise_link($receiver)];
1083                                 $contact = DBA::selectFirst('contact', ['uid'], $condition);
1084                                 if (!DBA::isResult($contact)) {
1085                                         continue;
1086                                 }
1087                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
1088                         }
1089                 }
1090                 return $receivers;
1091         }
1092
1093         private static function addActivityFields($object_data, $activity)
1094         {
1095                 if (!empty($activity['published']) && empty($object_data['published'])) {
1096                         $object_data['published'] = $activity['published'];
1097                 }
1098
1099                 if (!empty($activity['updated']) && empty($object_data['updated'])) {
1100                         $object_data['updated'] = $activity['updated'];
1101                 }
1102
1103                 if (!empty($activity['inReplyTo']) && empty($object_data['parent-uri'])) {
1104                         $object_data['parent-uri'] = self::processElement($activity, 'inReplyTo', 'id');
1105                 }
1106
1107                 if (!empty($activity['instrument'])) {
1108                         $object_data['service'] = self::processElement($activity, 'instrument', 'name', 'type', 'Service');
1109                 }
1110                 return $object_data;
1111         }
1112
1113         private static function fetchObject($object_url, $object = [], $public = true)
1114         {
1115                 if ($public) {
1116                         $data = self::fetchContent($object_url);
1117                         if (empty($data)) {
1118                                 logger('Empty content for ' . $object_url . ', check if content is available locally.', LOGGER_DEBUG);
1119                                 $data = $object_url;
1120                                 $data = $object;
1121                         }
1122                 } else {
1123                         logger('Using original object for url ' . $object_url, LOGGER_DEBUG);
1124                         $data = $object;
1125                 }
1126
1127                 if (is_string($data)) {
1128                         $item = Item::selectFirst([], ['uri' => $data]);
1129                         if (!DBA::isResult($item)) {
1130                                 logger('Object with url ' . $data . ' was not found locally.', LOGGER_DEBUG);
1131                                 return false;
1132                         }
1133                         logger('Using already stored item for url ' . $object_url, LOGGER_DEBUG);
1134                         $data = self::createNote($item);
1135                 }
1136
1137                 if (empty($data['type'])) {
1138                         logger('Empty type', LOGGER_DEBUG);
1139                         return false;
1140                 } else {
1141                         $type = $data['type'];
1142                         logger('Type ' . $type, LOGGER_DEBUG);
1143                 }
1144
1145                 if (in_array($type, ['Note', 'Article', 'Video'])) {
1146                         $common = self::processCommonData($data);
1147                 }
1148
1149                 switch ($type) {
1150                         case 'Note':
1151                                 return array_merge($common, self::processNote($data));
1152                         case 'Article':
1153                                 return array_merge($common, self::processArticle($data));
1154                         case 'Video':
1155                                 return array_merge($common, self::processVideo($data));
1156
1157                         case 'Announce':
1158                                 if (empty($data['object'])) {
1159                                         return false;
1160                                 }
1161                                 return self::fetchObject($data['object']);
1162
1163                         case 'Person':
1164                         case 'Tombstone':
1165                                 break;
1166
1167                         default:
1168                                 logger('Unknown object type: ' . $data['type'], LOGGER_DEBUG);
1169                                 break;
1170                 }
1171         }
1172
1173         private static function processCommonData(&$object)
1174         {
1175                 if (empty($object['id'])) {
1176                         return false;
1177                 }
1178
1179                 $object_data = [];
1180                 $object_data['type'] = $object['type'];
1181                 $object_data['uri'] = $object['id'];
1182
1183                 if (!empty($object['inReplyTo'])) {
1184                         $object_data['reply-to-uri'] = self::processElement($object, 'inReplyTo', 'id');
1185                 } else {
1186                         $object_data['reply-to-uri'] = $object_data['uri'];
1187                 }
1188
1189                 $object_data['published'] = defaults($object, 'published', null);
1190                 $object_data['updated'] = defaults($object, 'updated', $object_data['published']);
1191
1192                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
1193                         $object_data['published'] = $object_data['updated'];
1194                 }
1195
1196                 $object_data['uuid'] = defaults($object, 'uuid', null);
1197                 $object_data['owner'] = $object_data['author'] = self::processElement($object, 'attributedTo', 'id');
1198                 $object_data['context'] = defaults($object, 'context', null);
1199                 $object_data['conversation'] = defaults($object, 'conversation', null);
1200                 $object_data['sensitive'] = defaults($object, 'sensitive', null);
1201                 $object_data['name'] = defaults($object, 'title', null);
1202                 $object_data['name'] = defaults($object, 'name', $object_data['name']);
1203                 $object_data['summary'] = defaults($object, 'summary', null);
1204                 $object_data['content'] = defaults($object, 'content', null);
1205                 $object_data['source'] = defaults($object, 'source', null);
1206                 $object_data['location'] = self::processElement($object, 'location', 'name', 'type', 'Place');
1207                 $object_data['attachments'] = defaults($object, 'attachment', null);
1208                 $object_data['tags'] = defaults($object, 'tag', null);
1209                 $object_data['service'] = self::processElement($object, 'instrument', 'name', 'type', 'Service');
1210                 $object_data['alternate-url'] = self::processElement($object, 'url', 'href');
1211                 $object_data['receiver'] = self::getReceivers($object, $object_data['owner']);
1212
1213                 // Unhandled
1214                 // @context, type, actor, signature, mediaType, duration, replies, icon
1215
1216                 // Also missing: (Defined in the standard, but currently unused)
1217                 // audience, preview, endTime, startTime, generator, image
1218
1219                 return $object_data;
1220         }
1221
1222         private static function processNote($object)
1223         {
1224                 $object_data = [];
1225
1226                 // To-Do?
1227                 // emoji, atomUri, inReplyToAtomUri
1228
1229                 // Unhandled
1230                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1231                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1232
1233                 return $object_data;
1234         }
1235
1236         private static function processArticle($object)
1237         {
1238                 $object_data = [];
1239
1240                 return $object_data;
1241         }
1242
1243         private static function processVideo($object)
1244         {
1245                 $object_data = [];
1246
1247                 // To-Do?
1248                 // category, licence, language, commentsEnabled
1249
1250                 // Unhandled
1251                 // views, waitTranscoding, state, support, subtitleLanguage
1252                 // likes, dislikes, shares, comments
1253
1254                 return $object_data;
1255         }
1256
1257         private static function processElement($array, $element, $key, $type = null, $type_value = null)
1258         {
1259                 if (empty($array)) {
1260                         return false;
1261                 }
1262
1263                 if (empty($array[$element])) {
1264                         return false;
1265                 }
1266
1267                 if (is_string($array[$element])) {
1268                         return $array[$element];
1269                 }
1270
1271                 if (is_null($type_value)) {
1272                         if (!empty($array[$element][$key])) {
1273                                 return $array[$element][$key];
1274                         }
1275
1276                         if (!empty($array[$element][0][$key])) {
1277                                 return $array[$element][0][$key];
1278                         }
1279
1280                         return false;
1281                 }
1282
1283                 if (!empty($array[$element][$key]) && !empty($array[$element][$type]) && ($array[$element][$type] == $type_value)) {
1284                         return $array[$element][$key];
1285                 }
1286
1287                 /// @todo Add array search
1288
1289                 return false;
1290         }
1291
1292         private static function convertMentions($body)
1293         {
1294                 $URLSearchString = "^\[\]";
1295                 $body = preg_replace("/\[url\=([$URLSearchString]*)\]([#@!])(.*?)\[\/url\]/ism", '$2[url=$1]$3[/url]', $body);
1296
1297                 return $body;
1298         }
1299
1300         private static function constructTagList($tags, $sensitive)
1301         {
1302                 if (empty($tags)) {
1303                         return '';
1304                 }
1305
1306                 $tag_text = '';
1307                 foreach ($tags as $tag) {
1308                         if (in_array($tag['type'], ['Mention', 'Hashtag'])) {
1309                                 if (!empty($tag_text)) {
1310                                         $tag_text .= ',';
1311                                 }
1312
1313                                 if (empty($tag['href'])) {
1314                                         //$tag['href']
1315                                         logger('Blubb!');
1316                                 }
1317
1318                                 $tag_text .= substr($tag['name'], 0, 1) . '[url=' . $tag['href'] . ']' . substr($tag['name'], 1) . '[/url]';
1319                         }
1320                 }
1321
1322                 /// @todo add nsfw for $sensitive
1323
1324                 return $tag_text;
1325         }
1326
1327         private static function constructAttachList($attachments, $item)
1328         {
1329                 if (empty($attachments)) {
1330                         return $item;
1331                 }
1332
1333                 foreach ($attachments as $attach) {
1334                         $filetype = strtolower(substr($attach['mediaType'], 0, strpos($attach['mediaType'], '/')));
1335                         if ($filetype == 'image') {
1336                                 $item['body'] .= "\n[img]".$attach['url'].'[/img]';
1337                         } else {
1338                                 if (!empty($item["attach"])) {
1339                                         $item["attach"] .= ',';
1340                                 } else {
1341                                         $item["attach"] = '';
1342                                 }
1343                                 if (!isset($attach['length'])) {
1344                                         $attach['length'] = "0";
1345                                 }
1346                                 $item["attach"] .= '[attach]href="'.$attach['url'].'" length="'.$attach['length'].'" type="'.$attach['mediaType'].'" title="'.defaults($attach, 'name', '').'"[/attach]';
1347                         }
1348                 }
1349
1350                 return $item;
1351         }
1352
1353         private static function createItem($activity, $body)
1354         {
1355                 $item = [];
1356                 $item['verb'] = ACTIVITY_POST;
1357                 $item['parent-uri'] = $activity['reply-to-uri'];
1358
1359                 if ($activity['reply-to-uri'] == $activity['uri']) {
1360                         $item['gravity'] = GRAVITY_PARENT;
1361                         $item['object-type'] = ACTIVITY_OBJ_NOTE;
1362                 } else {
1363                         $item['gravity'] = GRAVITY_COMMENT;
1364                         $item['object-type'] = ACTIVITY_OBJ_COMMENT;
1365                 }
1366
1367                 if (($activity['uri'] != $activity['reply-to-uri']) && !Item::exists(['uri' => $activity['reply-to-uri']])) {
1368                         logger('Parent ' . $activity['reply-to-uri'] . ' not found. Try to refetch it.');
1369                         self::fetchMissingActivity($activity['reply-to-uri'], $activity);
1370                 }
1371
1372                 self::postItem($activity, $item, $body);
1373         }
1374
1375         private static function likeItem($activity, $body)
1376         {
1377                 $item = [];
1378                 $item['verb'] = ACTIVITY_LIKE;
1379                 $item['parent-uri'] = $activity['object'];
1380                 $item['gravity'] = GRAVITY_ACTIVITY;
1381                 $item['object-type'] = ACTIVITY_OBJ_NOTE;
1382
1383                 self::postItem($activity, $item, $body);
1384         }
1385
1386         private static function postItem($activity, $item, $body)
1387         {
1388                 /// @todo What to do with $activity['context']?
1389
1390                 $item['network'] = Protocol::ACTIVITYPUB;
1391                 $item['private'] = !in_array(0, $activity['receiver']);
1392                 $item['author-id'] = Contact::getIdForURL($activity['author'], 0, true);
1393                 $item['owner-id'] = Contact::getIdForURL($activity['owner'], 0, true);
1394                 $item['uri'] = $activity['uri'];
1395                 $item['created'] = $activity['published'];
1396                 $item['edited'] = $activity['updated'];
1397                 $item['guid'] = $activity['uuid'];
1398                 $item['title'] = HTML::toBBCode($activity['name']);
1399                 $item['content-warning'] = HTML::toBBCode($activity['summary']);
1400                 $item['body'] = self::convertMentions(HTML::toBBCode($activity['content']));
1401                 $item['location'] = $activity['location'];
1402                 $item['tag'] = self::constructTagList($activity['tags'], $activity['sensitive']);
1403                 $item['app'] = $activity['service'];
1404                 $item['plink'] = defaults($activity, 'alternate-url', $item['uri']);
1405
1406                 $item = self::constructAttachList($activity['attachments'], $item);
1407
1408                 $source = self::processElement($activity, 'source', 'content', 'mediaType', 'text/bbcode');
1409                 if (!empty($source)) {
1410                         $item['body'] = $source;
1411                 }
1412
1413                 $item['protocol'] = Conversation::PARCEL_ACTIVITYPUB;
1414                 $item['source'] = $body;
1415                 $item['conversation-uri'] = $activity['conversation'];
1416
1417                 foreach ($activity['receiver'] as $receiver) {
1418                         $item['uid'] = $receiver;
1419                         $item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver, true);
1420
1421                         if (($receiver != 0) && empty($item['contact-id'])) {
1422                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], 0, true);
1423                         }
1424
1425                         $item_id = Item::insert($item);
1426                         logger('Storing for user ' . $item['uid'] . ': ' . $item_id);
1427                 }
1428         }
1429
1430         private static function fetchMissingActivity($url, $child)
1431         {
1432                 $object = ActivityPub::fetchContent($url);
1433                 if (empty($object)) {
1434                         logger('Activity ' . $url . ' was not fetchable, aborting.');
1435                         return;
1436                 }
1437
1438                 $activity = [];
1439                 $activity['@context'] = $object['@context'];
1440                 unset($object['@context']);
1441                 $activity['id'] = $object['id'];
1442                 $activity['to'] = defaults($object, 'to', []);
1443                 $activity['cc'] = defaults($object, 'cc', []);
1444                 $activity['actor'] = $child['author'];
1445                 $activity['object'] = $object;
1446                 $activity['published'] = $object['published'];
1447                 $activity['type'] = 'Create';
1448                 self::processActivity($activity);
1449                 logger('Activity ' . $url . ' had been fetched and processed.');
1450         }
1451
1452         private static function getUserOfObject($object)
1453         {
1454                 $self = DBA::selectFirst('contact', ['uid'], ['nurl' => normalise_link($object), 'self' => true]);
1455                 if (!DBA::isResult($self)) {
1456                         return false;
1457                 } else {
1458                         return $self['uid'];
1459                 }
1460         }
1461
1462         private static function followUser($activity)
1463         {
1464                 $uid = self::getUserOfObject($activity['object']);
1465                 if (empty($uid)) {
1466                         return;
1467                 }
1468
1469                 $owner = User::getOwnerDataById($uid);
1470
1471                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1472                 if (!empty($cid)) {
1473                         $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
1474                 } else {
1475                         $contact = false;
1476                 }
1477
1478                 $item = ['author-id' => Contact::getIdForURL($activity['owner']),
1479                         'author-link' => $activity['owner']];
1480
1481                 Contact::addRelationship($owner, $contact, $item);
1482                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1483                 if (empty($cid)) {
1484                         return;
1485                 }
1486
1487                 $contact = DBA::selectFirst('contact', ['network'], ['id' => $cid]);
1488                 if ($contact['network'] != Protocol::ACTIVITYPUB) {
1489                         Contact::updateFromProbe($cid, Protocol::ACTIVITYPUB);
1490                 }
1491
1492                 DBA::update('contact', ['hub-verify' => $activity['id']], ['id' => $cid]);
1493                 logger('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
1494         }
1495
1496         private static function acceptFollowUser($activity)
1497         {
1498                 $uid = self::getUserOfObject($activity['object']);
1499                 if (empty($uid)) {
1500                         return;
1501                 }
1502
1503                 $owner = User::getOwnerDataById($uid);
1504
1505                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1506                 if (empty($cid)) {
1507                         logger('No contact found for ' . $activity['owner'], LOGGER_DEBUG);
1508                         return;
1509                 }
1510
1511                 $fields = ['pending' => false];
1512
1513                 $contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
1514                 if ($contact['rel'] == Contact::FOLLOWER) {
1515                         $fields['rel'] = Contact::FRIEND;
1516                 }
1517
1518                 $condition = ['id' => $cid];
1519                 DBA::update('contact', $fields, $condition);
1520                 logger('Accept contact request from contact ' . $cid . ' for user ' . $uid, LOGGER_DEBUG);
1521         }
1522
1523         private static function undoFollowUser($activity)
1524         {
1525                 $uid = self::getUserOfObject($activity['object']);
1526                 if (empty($uid)) {
1527                         return;
1528                 }
1529
1530                 $owner = User::getOwnerDataById($uid);
1531
1532                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1533                 if (empty($cid)) {
1534                         logger('No contact found for ' . $activity['owner'], LOGGER_DEBUG);
1535                         return;
1536                 }
1537
1538                 $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
1539                 if (!DBA::isResult($contact)) {
1540                         return;
1541                 }
1542
1543                 Contact::removeFollower($owner, $contact);
1544                 logger('Undo following request from contact ' . $cid . ' for user ' . $uid, LOGGER_DEBUG);
1545         }
1546 }