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