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 isRequest()
  59         {
  60                 return stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/activity+json') ||
  61                         stristr(defaults($_SERVER, 'HTTP_ACCEPT', ''), 'application/ld+json');
  62         }
  63
  64         public static function transmit($data, $target, $uid)
  65         {
  66                 $owner = User::getOwnerDataById($uid);
  67
  68                 if (!$owner) {
  69                         return;
  70                 }
  71
  72                 $content = json_encode($data);
  73
  74                 // Header data that is about to be signed.
  75                 $host = parse_url($target, PHP_URL_HOST);
  76                 $path = parse_url($target, PHP_URL_PATH);
  77                 $digest = 'SHA-256=' . base64_encode(hash('sha256', $content, true));
  78                 $content_length = strlen($content);
  79
  80                 $headers = ['Content-Length: ' . $content_length, 'Digest: ' . $digest, 'Host: ' . $host];
  81
  82                 $signed_data = "(request-target): post " . $path . "\ncontent-length: " . $content_length . "\ndigest: " . $digest . "\nhost: " . $host;
  83
  84                 $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
  85
  86                 $headers[] = 'Signature: keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) content-length digest host",signature="' . $signature . '"';
  87
  88                 $headers[] = 'Content-Type: application/activity+json';
  89
  90                 Network::post($target, $content, $headers);
  91                 $return_code = BaseObject::getApp()->get_curl_code();
  92
  93                 logger('Transmit to ' . $target . ' returned ' . $return_code);
  94         }
  95
  96         /**
  97          * Return the ActivityPub profile of the given user
  98          *
  99          * @param integer $uid User ID
 100          * @return array
 101          */
 102         public static function profile($uid)
 103         {
 104                 $accounttype = ['Person', 'Organization', 'Service', 'Group', 'Application', 'page-flags'];
 105                 $condition = ['uid' => $uid, 'blocked' => false, 'account_expired' => false,
 106                         'account_removed' => false, 'verified' => true];
 107                 $fields = ['guid', 'nickname', 'pubkey', 'account-type'];
 108                 $user = DBA::selectFirst('user', $fields, $condition);
 109                 if (!DBA::isResult($user)) {
 110                         return [];
 111                 }
 112
 113                 $fields = ['locality', 'region', 'country-name'];
 114                 $profile = DBA::selectFirst('profile', $fields, ['uid' => $uid, 'is-default' => true]);
 115                 if (!DBA::isResult($profile)) {
 116                         return [];
 117                 }
 118
 119                 $fields = ['name', 'url', 'location', 'about', 'avatar'];
 120                 $contact = DBA::selectFirst('contact', $fields, ['uid' => $uid, 'self' => true]);
 121                 if (!DBA::isResult($contact)) {
 122                         return [];
 123                 }
 124
 125                 $data = ['@context' => ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1',
 126                         ['uuid' => 'http://schema.org/identifier', 'sensitive' => 'as:sensitive',
 127                         'manuallyApprovesFollowers' => 'as:manuallyApprovesFollowers',
 128                         'vcard' => 'http://www.w3.org/2006/vcard/ns#']]];
 129
 130                 $data['id'] = $contact['url'];
 131                 $data['uuid'] = $user['guid'];
 132                 $data['type'] = $accounttype[$user['account-type']];
 133                 $data['following'] = System::baseUrl() . '/following/' . $user['nickname'];
 134                 $data['followers'] = System::baseUrl() . '/followers/' . $user['nickname'];
 135                 $data['inbox'] = System::baseUrl() . '/inbox/' . $user['nickname'];
 136                 $data['outbox'] = System::baseUrl() . '/outbox/' . $user['nickname'];
 137                 $data['preferredUsername'] = $user['nickname'];
 138                 $data['name'] = $contact['name'];
 139                 $data['vcard:hasAddress'] = ['@type' => 'vcard:Home', 'vcard:country-name' => $profile['country-name'],
 140                         'vcard:region' => $profile['region'], 'vcard:locality' => $profile['locality']];
 141                 $data['summary'] = $contact['about'];
 142                 $data['url'] = $contact['url'];
 143                 $data['manuallyApprovesFollowers'] = in_array($profile['page-flags'], [Contact::PAGE_NORMAL, Contact::PAGE_PRVGROUP]);
 144                 $data['publicKey'] = ['id' => $contact['url'] . '#main-key',
 145                         'owner' => $contact['url'],
 146                         'publicKeyPem' => $user['pubkey']];
 147                 $data['endpoints'] = ['sharedInbox' => System::baseUrl() . '/inbox'];
 148                 $data['icon'] = ['type' => 'Image',
 149                         'url' => $contact['avatar']];
 150
 151                 // tags: https://kitty.town/@inmysocks/100656097926961126.json
 152                 return $data;
 153         }
 154
 155         public static function createActivityFromItem($item_id)
 156         {
 157                 $item = Item::selectFirst([], ['id' => $item_id]);
 158
 159                 $data = ['@context' => ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1',
 160                         ['Emoji' => 'toot:Emoji', 'Hashtag' => 'as:Hashtag', 'atomUri' => 'ostatus:atomUri',
 161                         'conversation' => 'ostatus:conversation', 'inReplyToAtomUri' => 'ostatus:inReplyToAtomUri',
 162                         'ostatus' => 'http://ostatus.org#', 'sensitive' => 'as:sensitive',
 163                         'toot' => 'http://joinmastodon.org/ns#']]];
 164
 165                 $data['type'] = 'Create';
 166                 $data['id'] = $item['uri'] . '/activity';
 167                 $data['actor'] = $item['author-link'];
 168                 $data['to'] = 'https://www.w3.org/ns/activitystreams#Public';
 169                 $data['object'] = self::createNote($item);
 170                 return $data;
 171         }
 172
 173         public static function createNote($item)
 174         {
 175                 $data = [];
 176                 $data['type'] = 'Note';
 177                 $data['id'] = $item['uri'];
 178
 179                 if ($item['uri'] != $item['thr-parent']) {
 180                         $data['inReplyTo'] = $item['thr-parent'];
 181                 }
 182
 183                 $conversation = DBA::selectFirst('conversation', ['conversation-uri'], ['item-uri' => $item['parent-uri']]);
 184                 if (DBA::isResult($conversation) && !empty($conversation['conversation-uri'])) {
 185                         $conversation_uri = $conversation['conversation-uri'];
 186                 } else {
 187                         $conversation_uri = $item['parent-uri'];
 188                 }
 189
 190                 $data['context'] = $data['conversation'] = $conversation_uri;
 191                 $data['actor'] = $item['author-link'];
 192                 if (!$item['private']) {
 193                         $data['to'] = 'https://www.w3.org/ns/activitystreams#Public';
 194                 }
 195                 $data['published'] = DateTimeFormat::utc($item["created"]."+00:00", DateTimeFormat::ATOM);
 196                 $data['updated'] = DateTimeFormat::utc($item["edited"]."+00:00", DateTimeFormat::ATOM);
 197                 $data['attributedTo'] = $item['author-link'];
 198                 $data['name'] = BBCode::convert($item['title'], false, 7);
 199                 $data['content'] = BBCode::convert($item['body'], false, 7);
 200                 $data['source'] = ['content' => $item['body'], 'mediaType' => "text/bbcode"];
 201                 //$data['summary'] = ''; // Ignore by now
 202                 //$data['sensitive'] = false; // - Query NSFW
 203                 //$data['emoji'] = []; // Ignore by now
 204                 //$data['tag'] = []; /// @ToDo
 205                 //$data['attachment'] = []; // @ToDo
 206                 return $data;
 207         }
 208
 209         public static function transmitActivity($activity, $target, $uid)
 210         {
 211                 $profile = Probe::uri($target, Protocol::ACTIVITYPUB);
 212
 213                 $owner = User::getOwnerDataById($uid);
 214
 215                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 216                         'id' => System::baseUrl() . '/activity/' . System::createGUID(),
 217                         'type' => $activity,
 218                         'actor' => $owner['url'],
 219                         'object' => $profile['url'],
 220                         'to' => $profile['url']];
 221
 222                 logger('Sending activity ' . $activity . ' to ' . $target . ' for user ' . $uid, LOGGER_DEBUG);
 223                 return self::transmit($data,  $profile['notify'], $uid);
 224         }
 225
 226         public static function transmitContactAccept($target, $id, $uid)
 227         {
 228                 $profile = Probe::uri($target, Protocol::ACTIVITYPUB);
 229
 230                 $owner = User::getOwnerDataById($uid);
 231                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 232                         'id' => System::baseUrl() . '/activity/' . System::createGUID(),
 233                         'type' => 'Accept',
 234                         'actor' => $owner['url'],
 235                         'object' => ['id' => $id, 'type' => 'Follow',
 236                                 'actor' => $profile['url'],
 237                                 'object' => $owner['url']],
 238                         'to' => $profile['url']];
 239
 240                 logger('Sending accept to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 241                 return self::transmit($data,  $profile['notify'], $uid);
 242         }
 243
 244         public static function transmitContactReject($target, $id, $uid)
 245         {
 246                 $profile = Probe::uri($target, Protocol::ACTIVITYPUB);
 247
 248                 $owner = User::getOwnerDataById($uid);
 249                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 250                         'id' => System::baseUrl() . '/activity/' . System::createGUID(),
 251                         'type' => 'Reject',
 252                         'actor' => $owner['url'],
 253                         'object' => ['id' => $id, 'type' => 'Follow',
 254                                 'actor' => $profile['url'],
 255                                 'object' => $owner['url']],
 256                         'to' => $profile['url']];
 257
 258                 logger('Sending reject to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 259                 return self::transmit($data,  $profile['notify'], $uid);
 260         }
 261
 262         public static function transmitContactUndo($target, $uid)
 263         {
 264                 $profile = Probe::uri($target, Protocol::ACTIVITYPUB);
 265
 266                 $id = System::baseUrl() . '/activity/' . System::createGUID();
 267
 268                 $owner = User::getOwnerDataById($uid);
 269                 $data = ['@context' => 'https://www.w3.org/ns/activitystreams',
 270                         'id' => $id,
 271                         'type' => 'Undo',
 272                         'actor' => $owner['url'],
 273                         'object' => ['id' => $id, 'type' => 'Follow',
 274                                 'actor' => $owner['url'],
 275                                 'object' => $profile['url']],
 276                         'to' => $profile['url']];
 277
 278                 logger('Sending undo to ' . $target . ' for user ' . $uid . ' with id ' . $id, LOGGER_DEBUG);
 279                 return self::transmit($data,  $profile['notify'], $uid);
 280         }
 281
 282         /**
 283          * Fetches ActivityPub content from the given url
 284          *
 285          * @param string $url content url
 286          * @return array
 287          */
 288         public static function fetchContent($url)
 289         {
 290                 $ret = Network::curl($url, false, $redirects, ['accept_content' => 'application/activity+json, application/ld+json']);
 291                 if (!$ret['success'] || empty($ret['body'])) {
 292                         return;
 293                 }
 294
 295                 return json_decode($ret['body'], true);
 296         }
 297
 298         /**
 299          * Resolves the profile url from the address by using webfinger
 300          *
 301          * @param string $addr profile address (user@domain.tld)
 302          * @return string url
 303          */
 304         private static function addrToUrl($addr)
 305         {
 306                 $addr_parts = explode('@', $addr);
 307                 if (count($addr_parts) != 2) {
 308                         return false;
 309                 }
 310
 311                 $webfinger = 'https://' . $addr_parts[1] . '/.well-known/webfinger?resource=acct:' . urlencode($addr);
 312
 313                 $ret = Network::curl($webfinger, false, $redirects, ['accept_content' => 'application/jrd+json,application/json']);
 314                 if (!$ret['success'] || empty($ret['body'])) {
 315                         return false;
 316                 }
 317
 318                 $data = json_decode($ret['body'], true);
 319
 320                 if (empty($data['links'])) {
 321                         return false;
 322                 }
 323
 324                 foreach ($data['links'] as $link) {
 325                         if (empty($link['href']) || empty($link['rel']) || empty($link['type'])) {
 326                                 continue;
 327                         }
 328
 329                         if (($link['rel'] == 'self') && ($link['type'] == 'application/activity+json')) {
 330                                 return $link['href'];
 331                         }
 332                 }
 333
 334                 return false;
 335         }
 336
 337         public static function verifySignature($content, $http_headers)
 338         {
 339                 $object = json_decode($content, true);
 340
 341                 if (empty($object)) {
 342                         return false;
 343                 }
 344
 345                 $actor = self::processElement($object, 'actor', 'id');
 346
 347                 $headers = [];
 348                 $headers['(request-target)'] = strtolower($http_headers['REQUEST_METHOD']) . ' ' . $http_headers['REQUEST_URI'];
 349
 350                 // First take every header
 351                 foreach ($http_headers as $k => $v) {
 352                         $field = str_replace('_', '-', strtolower($k));
 353                         $headers[$field] = $v;
 354                 }
 355
 356                 // Now add every http header
 357                 foreach ($http_headers as $k => $v) {
 358                         if (strpos($k, 'HTTP_') === 0) {
 359                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
 360                                 $headers[$field] = $v;
 361                         }
 362                 }
 363
 364                 $sig_block = ActivityPub::parseSigHeader($http_headers['HTTP_SIGNATURE']);
 365
 366                 if (empty($sig_block) || empty($sig_block['headers']) || empty($sig_block['keyId'])) {
 367                         return false;
 368                 }
 369
 370                 $signed_data = '';
 371                 foreach ($sig_block['headers'] as $h) {
 372                         if (array_key_exists($h, $headers)) {
 373                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
 374                         }
 375                 }
 376                 $signed_data = rtrim($signed_data, "\n");
 377
 378                 if (empty($signed_data)) {
 379                         return false;
 380                 }
 381
 382                 $algorithm = null;
 383
 384                 if ($sig_block['algorithm'] === 'rsa-sha256') {
 385                         $algorithm = 'sha256';
 386                 }
 387
 388                 if ($sig_block['algorithm'] === 'rsa-sha512') {
 389                         $algorithm = 'sha512';
 390                 }
 391
 392                 if (empty($algorithm)) {
 393                         return false;
 394                 }
 395
 396                 $key = self::fetchKey($sig_block['keyId'], $actor);
 397
 398                 if (empty($key)) {
 399                         return false;
 400                 }
 401
 402                 if (!Crypto::rsaVerify($signed_data, $sig_block['signature'], $key, $algorithm)) {
 403                         return false;
 404                 }
 405
 406                 // Check the digest when it is part of the signed data
 407                 if (in_array('digest', $sig_block['headers'])) {
 408                         $digest = explode('=', $headers['digest'], 2);
 409                         if ($digest[0] === 'SHA-256') {
 410                                 $hashalg = 'sha256';
 411                         }
 412                         if ($digest[0] === 'SHA-512') {
 413                                 $hashalg = 'sha512';
 414                         }
 415
 416                         /// @todo add all hashes from the rfc
 417
 418                         if (!empty($hashalg) && base64_encode(hash($hashalg, $content, true)) != $digest[1]) {
 419                                 return false;
 420                         }
 421                 }
 422
 423                 // Check the content-length when it is part of the signed data
 424                 if (in_array('content-length', $sig_block['headers'])) {
 425                         if (strlen($content) != $headers['content-length']) {
 426                                 return false;
 427                         }
 428                 }
 429
 430                 return true;
 431
 432         }
 433
 434         private static function fetchKey($id, $actor)
 435         {
 436                 $url = (strpos($id, '#') ? substr($id, 0, strpos($id, '#')) : $id);
 437
 438                 $profile = Probe::uri($url, Protocol::ACTIVITYPUB);
 439                 if (!empty($profile)) {
 440                         return $profile['pubkey'];
 441                 } elseif ($url != $actor) {
 442                         $profile = Probe::uri($actor, Protocol::ACTIVITYPUB);
 443                         if (!empty($profile)) {
 444                                 return $profile['pubkey'];
 445                         }
 446                 }
 447
 448                 return false;
 449         }
 450
 451         /**
 452          * @brief
 453          *
 454          * @param string $header
 455          * @return array associate array with
 456          *   - \e string \b keyID
 457          *   - \e string \b algorithm
 458          *   - \e array  \b headers
 459          *   - \e string \b signature
 460          */
 461         private static function parseSigHeader($header)
 462         {
 463                 $ret = [];
 464                 $matches = [];
 465
 466                 if (preg_match('/keyId="(.*?)"/ism',$header,$matches)) {
 467                         $ret['keyId'] = $matches[1];
 468                 }
 469
 470                 if (preg_match('/algorithm="(.*?)"/ism',$header,$matches)) {
 471                         $ret['algorithm'] = $matches[1];
 472                 }
 473
 474                 if (preg_match('/headers="(.*?)"/ism',$header,$matches)) {
 475                         $ret['headers'] = explode(' ', $matches[1]);
 476                 }
 477
 478                 if (preg_match('/signature="(.*?)"/ism',$header,$matches)) {
 479                         $ret['signature'] = base64_decode(preg_replace('/\s+/','',$matches[1]));
 480                 }
 481
 482                 return $ret;
 483         }
 484
 485         /**
 486          * Fetches a profile from the given url
 487          *
 488          * @param string $url profile url
 489          * @return array
 490          */
 491         public static function fetchProfile($url)
 492         {
 493                 if (empty(parse_url($url, PHP_URL_SCHEME))) {
 494                         $url = self::addrToUrl($url);
 495                         if (empty($url)) {
 496                                 return false;
 497                         }
 498                 }
 499
 500                 $data = self::fetchContent($url);
 501
 502                 if (empty($data) || empty($data['id']) || empty($data['inbox'])) {
 503                         return false;
 504                 }
 505
 506                 $profile = ['network' => Protocol::ACTIVITYPUB];
 507                 $profile['nick'] = $data['preferredUsername'];
 508                 $profile['name'] = defaults($data, 'name', $profile['nick']);
 509                 $profile['guid'] = defaults($data, 'uuid', null);
 510                 $profile['url'] = $data['id'];
 511
 512                 $parts = parse_url($profile['url']);
 513                 unset($parts['scheme']);
 514                 unset($parts['path']);
 515                 $profile['addr'] = $profile['nick'] . '@' . str_replace('//', '', Network::unparseURL($parts));
 516                 $profile['alias'] = self::processElement($data, 'url', 'href');
 517                 $profile['photo'] = self::processElement($data, 'icon', 'url');
 518                 // $profile['community']
 519                 // $profile['keywords']
 520                 // $profile['location']
 521                 $profile['about'] = defaults($data, 'summary', '');
 522                 $profile['batch'] = self::processElement($data, 'endpoints', 'sharedInbox');
 523                 $profile['notify'] = $data['inbox'];
 524                 $profile['poll'] = $data['outbox'];
 525                 $profile['pubkey'] = self::processElement($data, 'publicKey', 'publicKeyPem');
 526
 527                 // Check if the address is resolvable
 528                 if (self::addrToUrl($profile['addr']) == $profile['url']) {
 529                         $parts = parse_url($profile['url']);
 530                         unset($parts['path']);
 531                         $profile['baseurl'] = Network::unparseURL($parts);
 532                 } else {
 533                         unset($profile['addr']);
 534                 }
 535
 536                 if ($profile['url'] == $profile['alias']) {
 537                         unset($profile['alias']);
 538                 }
 539
 540                 // Remove all "null" fields
 541                 foreach ($profile as $field => $content) {
 542                         if (is_null($content)) {
 543                                 unset($profile[$field]);
 544                         }
 545                 }
 546
 547                 // To-Do
 548                 // type, manuallyApprovesFollowers
 549
 550                 // Unhandled
 551                 // @context, tag, attachment, image, nomadicLocations, signature, following, followers, featured, movedTo, liked
 552
 553                 // Unhandled from Misskey
 554                 // sharedInbox, isCat
 555
 556                 // Unhandled from Kroeg
 557                 // kroeg:blocks, updated
 558
 559                 return $profile;
 560         }
 561
 562         public static function processInbox($body, $header, $uid)
 563         {
 564                 logger('Incoming message for user ' . $uid, LOGGER_DEBUG);
 565
 566                 if (!self::verifySignature($body, $header)) {
 567                         logger('Invalid signature, message will be discarded.', LOGGER_DEBUG);
 568                         return;
 569                 }
 570
 571                 $activity = json_decode($body, true);
 572
 573                 if (!is_array($activity)) {
 574                         logger('Invalid body.', LOGGER_DEBUG);
 575                         return;
 576                 }
 577
 578                 self::processActivity($activity, $body, $uid);
 579         }
 580
 581         public static function fetchOutbox($url)
 582         {
 583                 $data = self::fetchContent($url);
 584                 if (empty($data)) {
 585                         return;
 586                 }
 587
 588                 if (!empty($data['orderedItems'])) {
 589                         $items = $data['orderedItems'];
 590                 } elseif (!empty($data['first']['orderedItems'])) {
 591                         $items = $data['first']['orderedItems'];
 592                 } elseif (!empty($data['first'])) {
 593                         self::fetchOutbox($data['first']);
 594                         return;
 595                 } else {
 596                         $items = [];
 597                 }
 598
 599                 foreach ($items as $activity) {
 600                         self::processActivity($activity);
 601                 }
 602         }
 603
 604         private static function prepareObjectData($activity, $uid)
 605         {
 606                 $actor = self::processElement($activity, 'actor', 'id');
 607                 if (empty($actor)) {
 608                         logger('Empty actor', LOGGER_DEBUG);
 609                         return [];
 610                 }
 611
 612                 // Fetch all receivers from to, cc, bto and bcc
 613                 $receivers = self::getReceivers($activity, $actor);
 614
 615                 // When it is a delivery to a personal inbox we add that user to the receivers
 616                 if (!empty($uid)) {
 617                         $owner = User::getOwnerDataById($uid);
 618                         $additional = ['uid:' . $uid => $uid];
 619                         $receivers = array_merge($receivers, $additional);
 620                 }
 621
 622                 logger('Receivers: ' . json_encode($receivers), LOGGER_DEBUG);
 623
 624                 $public = in_array(0, $receivers);
 625
 626                 if (is_string($activity['object'])) {
 627                         $object_url = $activity['object'];
 628                 } elseif (!empty($activity['object']['id'])) {
 629                         $object_url = $activity['object']['id'];
 630                 } else {
 631                         logger('No object found', LOGGER_DEBUG);
 632                         return [];
 633                 }
 634
 635                 // Fetch the content only on activities where this matters
 636                 if (in_array($activity['type'], ['Create', 'Update', 'Announce'])) {
 637                         $object_data = self::fetchObject($object_url, $activity['object']);
 638                         if (empty($object_data)) {
 639                                 logger("Object data couldn't be processed", LOGGER_DEBUG);
 640                                 return [];
 641                         }
 642                 } elseif ($activity['type'] == 'Accept') {
 643                         $object_data = [];
 644                         $object_data['object_type'] = self::processElement($activity, 'object', 'type');
 645                         $object_data['object'] = self::processElement($activity, 'object', 'actor');
 646                 } elseif ($activity['type'] == 'Undo') {
 647                         $object_data = [];
 648                         $object_data['object_type'] = self::processElement($activity, 'object', 'type');
 649                         $object_data['object'] = self::processElement($activity, 'object', 'object');
 650                 } elseif (in_array($activity['type'], ['Like', 'Dislike'])) {
 651                         // Create a mostly empty array out of the activity data (instead of the object).
 652                         // This way we later don't have to check for the existence of ech individual array element.
 653                         $object_data = self::processCommonData($activity);
 654                         $object_data['name'] = $activity['type'];
 655                         $object_data['author'] = $activity['actor'];
 656                         $object_data['object'] = $object_url;
 657                 } elseif ($activity['type'] == 'Follow') {
 658                         $object_data['id'] = $activity['id'];
 659                         $object_data['object'] = $object_url;
 660                 } else {
 661                         $object_data = [];
 662                 }
 663
 664                 $object_data = self::addActivityFields($object_data, $activity);
 665
 666                 $object_data['type'] = $activity['type'];
 667                 $object_data['owner'] = $actor;
 668                 $object_data['receiver'] = array_merge(defaults($object_data, 'receiver', []), $receivers);
 669
 670                 return $object_data;
 671         }
 672
 673         private static function processActivity($activity, $body = '', $uid = null)
 674         {
 675                 if (empty($activity['type'])) {
 676                         logger('Empty type', LOGGER_DEBUG);
 677                         return;
 678                 }
 679
 680                 if (empty($activity['object'])) {
 681                         logger('Empty object', LOGGER_DEBUG);
 682                         return;
 683                 }
 684
 685                 if (empty($activity['actor'])) {
 686                         logger('Empty actor', LOGGER_DEBUG);
 687                         return;
 688
 689                 }
 690
 691                 // Non standard
 692                 // title, atomUri, context_id, statusnetConversationId
 693
 694                 // To-Do?
 695                 // context, location, signature;
 696
 697                 logger('Processing activity: ' . $activity['type'], LOGGER_DEBUG);
 698
 699                 $object_data = self::prepareObjectData($activity, $uid);
 700                 if (empty($object_data)) {
 701                         logger('No object data found', LOGGER_DEBUG);
 702                         return;
 703                 }
 704
 705                 switch ($activity['type']) {
 706                         case 'Create':
 707                         case 'Announce':
 708                                 self::createItem($object_data, $body);
 709                                 break;
 710
 711                         case 'Like':
 712                                 self::likeItem($object_data, $body);
 713                                 break;
 714
 715                         case 'Dislike':
 716                                 break;
 717
 718                         case 'Update':
 719                                 break;
 720
 721                         case 'Delete':
 722                                 break;
 723
 724                         case 'Follow':
 725                                 self::followUser($object_data);
 726                                 break;
 727
 728                         case 'Accept':
 729                                 if ($object_data['object_type'] == 'Follow') {
 730                                         self::acceptFollowUser($object_data);
 731                                 }
 732                                 break;
 733
 734                         case 'Undo':
 735                                 if ($object_data['object_type'] == 'Follow') {
 736                                         self::undoFollowUser($object_data);
 737                                 }
 738                                 break;
 739
 740                         default:
 741                                 logger('Unknown activity: ' . $activity['type'], LOGGER_DEBUG);
 742                                 break;
 743                 }
 744         }
 745
 746         private static function getReceivers($activity, $actor)
 747         {
 748                 $receivers = [];
 749
 750                 if (!empty($actor)) {
 751                         $data = self::fetchContent($actor);
 752                         $followers = defaults($data, 'followers', '');
 753
 754                         logger('Actor: ' . $actor . ' - Followers: ' . $followers, LOGGER_DEBUG);
 755                 } else {
 756                         logger('Empty actor', LOGGER_DEBUG);
 757                         $followers = '';
 758                 }
 759
 760                 $elements = ['to', 'cc', 'bto', 'bcc'];
 761                 foreach ($elements as $element) {
 762                         if (empty($activity[$element])) {
 763                                 continue;
 764                         }
 765
 766                         // The receiver can be an arror or a string
 767                         if (is_string($activity[$element])) {
 768                                 $activity[$element] = [$activity[$element]];
 769                         }
 770
 771                         foreach ($activity[$element] as $receiver) {
 772                                 if ($receiver == self::PUBLIC) {
 773                                         $receivers['uid:0'] = 0;
 774                                 }
 775
 776                                 if (($receiver == self::PUBLIC) && !empty($actor)) {
 777                                         // This will most likely catch all OStatus connections to Mastodon
 778                                         $condition = ['alias' => [$actor, normalise_link($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]];
 779                                         $contacts = DBA::select('contact', ['uid'], $condition);
 780                                         while ($contact = DBA::fetch($contacts)) {
 781                                                 if ($contact['uid'] != 0) {
 782                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 783                                                 }
 784                                         }
 785                                         DBA::close($contacts);
 786                                 }
 787
 788                                 if (in_array($receiver, [$followers, self::PUBLIC]) && !empty($actor)) {
 789                                         $condition = ['nurl' => normalise_link($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
 790                                                 'network' => Protocol::ACTIVITYPUB];
 791                                         $contacts = DBA::select('contact', ['uid'], $condition);
 792                                         while ($contact = DBA::fetch($contacts)) {
 793                                                 if ($contact['uid'] != 0) {
 794                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
 795                                                 }
 796                                         }
 797                                         DBA::close($contacts);
 798                                         continue;
 799                                 }
 800
 801                                 $condition = ['self' => true, 'nurl' => normalise_link($receiver)];
 802                                 $contact = DBA::selectFirst('contact', ['uid'], $condition);
 803                                 if (!DBA::isResult($contact)) {
 804                                         continue;
 805                                 }
 806                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
 807                         }
 808                 }
 809                 return $receivers;
 810         }
 811
 812         private static function addActivityFields($object_data, $activity)
 813         {
 814                 if (!empty($activity['published']) && empty($object_data['published'])) {
 815                         $object_data['published'] = $activity['published'];
 816                 }
 817
 818                 if (!empty($activity['updated']) && empty($object_data['updated'])) {
 819                         $object_data['updated'] = $activity['updated'];
 820                 }
 821
 822                 if (!empty($activity['inReplyTo']) && empty($object_data['parent-uri'])) {
 823                         $object_data['parent-uri'] = self::processElement($activity, 'inReplyTo', 'id');
 824                 }
 825
 826                 if (!empty($activity['instrument'])) {
 827                         $object_data['service'] = self::processElement($activity, 'instrument', 'name', 'type', 'Service');
 828                 }
 829                 return $object_data;
 830         }
 831
 832         private static function fetchObject($object_url, $object = [], $public = true)
 833         {
 834                 if ($public) {
 835                         $data = self::fetchContent($object_url);
 836                         if (empty($data)) {
 837                                 logger('Empty content for ' . $object_url . ', check if content is available locally.', LOGGER_DEBUG);
 838                                 $data = $object_url;
 839                                 $data = $object;
 840                         }
 841                 } else {
 842                         logger('Using original object for url ' . $object_url, LOGGER_DEBUG);
 843                         $data = $object;
 844                 }
 845
 846                 if (is_string($data)) {
 847                         $item = Item::selectFirst([], ['uri' => $data]);
 848                         if (!DBA::isResult($item)) {
 849                                 logger('Object with url ' . $data . ' was not found locally.', LOGGER_DEBUG);
 850                                 return false;
 851                         }
 852                         logger('Using already stored item for url ' . $object_url, LOGGER_DEBUG);
 853                         $data = self::createNote($item);
 854                 }
 855
 856                 if (empty($data['type'])) {
 857                         logger('Empty type', LOGGER_DEBUG);
 858                         return false;
 859                 } else {
 860                         $type = $data['type'];
 861                         logger('Type ' . $type, LOGGER_DEBUG);
 862                 }
 863
 864                 if (in_array($type, ['Note', 'Article', 'Video'])) {
 865                         $common = self::processCommonData($data);
 866                 }
 867
 868                 switch ($type) {
 869                         case 'Note':
 870                                 return array_merge($common, self::processNote($data));
 871                         case 'Article':
 872                                 return array_merge($common, self::processArticle($data));
 873                         case 'Video':
 874                                 return array_merge($common, self::processVideo($data));
 875
 876                         case 'Announce':
 877                                 if (empty($data['object'])) {
 878                                         return false;
 879                                 }
 880                                 return self::fetchObject($data['object']);
 881
 882                         case 'Person':
 883                         case 'Tombstone':
 884                                 break;
 885
 886                         default:
 887                                 logger('Unknown object type: ' . $data['type'], LOGGER_DEBUG);
 888                                 break;
 889                 }
 890         }
 891
 892         private static function processCommonData(&$object)
 893         {
 894                 if (empty($object['id'])) {
 895                         return false;
 896                 }
 897
 898                 $object_data = [];
 899                 $object_data['type'] = $object['type'];
 900                 $object_data['uri'] = $object['id'];
 901
 902                 if (!empty($object['inReplyTo'])) {
 903                         $object_data['reply-to-uri'] = self::processElement($object, 'inReplyTo', 'id');
 904                 } else {
 905                         $object_data['reply-to-uri'] = $object_data['uri'];
 906                 }
 907
 908                 $object_data['published'] = defaults($object, 'published', null);
 909                 $object_data['updated'] = defaults($object, 'updated', $object_data['published']);
 910
 911                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
 912                         $object_data['published'] = $object_data['updated'];
 913                 }
 914
 915                 $object_data['uuid'] = defaults($object, 'uuid', null);
 916                 $object_data['owner'] = $object_data['author'] = self::processElement($object, 'attributedTo', 'id');
 917                 $object_data['context'] = defaults($object, 'context', null);
 918                 $object_data['conversation'] = defaults($object, 'conversation', null);
 919                 $object_data['sensitive'] = defaults($object, 'sensitive', null);
 920                 $object_data['name'] = defaults($object, 'title', null);
 921                 $object_data['name'] = defaults($object, 'name', $object_data['name']);
 922                 $object_data['summary'] = defaults($object, 'summary', null);
 923                 $object_data['content'] = defaults($object, 'content', null);
 924                 $object_data['source'] = defaults($object, 'source', null);
 925                 $object_data['location'] = self::processElement($object, 'location', 'name', 'type', 'Place');
 926                 $object_data['attachments'] = defaults($object, 'attachment', null);
 927                 $object_data['tags'] = defaults($object, 'tag', null);
 928                 $object_data['service'] = self::processElement($object, 'instrument', 'name', 'type', 'Service');
 929                 $object_data['alternate-url'] = self::processElement($object, 'url', 'href');
 930                 $object_data['receiver'] = self::getReceivers($object, $object_data['owner']);
 931
 932                 // Unhandled
 933                 // @context, type, actor, signature, mediaType, duration, replies, icon
 934
 935                 // Also missing: (Defined in the standard, but currently unused)
 936                 // audience, preview, endTime, startTime, generator, image
 937
 938                 return $object_data;
 939         }
 940
 941         private static function processNote($object)
 942         {
 943                 $object_data = [];
 944
 945                 // To-Do?
 946                 // emoji, atomUri, inReplyToAtomUri
 947
 948                 // Unhandled
 949                 // contentMap, announcement_count, announcements, context_id, likes, like_count
 950                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
 951
 952                 return $object_data;
 953         }
 954
 955         private static function processArticle($object)
 956         {
 957                 $object_data = [];
 958
 959                 return $object_data;
 960         }
 961
 962         private static function processVideo($object)
 963         {
 964                 $object_data = [];
 965
 966                 // To-Do?
 967                 // category, licence, language, commentsEnabled
 968
 969                 // Unhandled
 970                 // views, waitTranscoding, state, support, subtitleLanguage
 971                 // likes, dislikes, shares, comments
 972
 973                 return $object_data;
 974         }
 975
 976         private static function processElement($array, $element, $key, $type = null, $type_value = null)
 977         {
 978                 if (empty($array)) {
 979                         return false;
 980                 }
 981
 982                 if (empty($array[$element])) {
 983                         return false;
 984                 }
 985
 986                 if (is_string($array[$element])) {
 987                         return $array[$element];
 988                 }
 989
 990                 if (is_null($type_value)) {
 991                         if (!empty($array[$element][$key])) {
 992                                 return $array[$element][$key];
 993                         }
 994
 995                         if (!empty($array[$element][0][$key])) {
 996                                 return $array[$element][0][$key];
 997                         }
 998
 999                         return false;
1000                 }
1001
1002                 if (!empty($array[$element][$key]) && !empty($array[$element][$type]) && ($array[$element][$type] == $type_value)) {
1003                         return $array[$element][$key];
1004                 }
1005
1006                 /// @todo Add array search
1007
1008                 return false;
1009         }
1010
1011         private static function convertMentions($body)
1012         {
1013                 $URLSearchString = "^\[\]";
1014                 $body = preg_replace("/\[url\=([$URLSearchString]*)\]([#@!])(.*?)\[\/url\]/ism", '$2[url=$1]$3[/url]', $body);
1015
1016                 return $body;
1017         }
1018
1019         private static function constructTagList($tags, $sensitive)
1020         {
1021                 if (empty($tags)) {
1022                         return '';
1023                 }
1024
1025                 $tag_text = '';
1026                 foreach ($tags as $tag) {
1027                         if (in_array($tag['type'], ['Mention', 'Hashtag'])) {
1028                                 if (!empty($tag_text)) {
1029                                         $tag_text .= ',';
1030                                 }
1031
1032                                 $tag_text .= substr($tag['name'], 0, 1) . '[url=' . $tag['href'] . ']' . substr($tag['name'], 1) . '[/url]';
1033                         }
1034                 }
1035
1036                 /// @todo add nsfw for $sensitive
1037
1038                 return $tag_text;
1039         }
1040
1041         private static function constructAttachList($attachments, $item)
1042         {
1043                 if (empty($attachments)) {
1044                         return $item;
1045                 }
1046
1047                 foreach ($attachments as $attach) {
1048                         $filetype = strtolower(substr($attach['mediaType'], 0, strpos($attach['mediaType'], '/')));
1049                         if ($filetype == 'image') {
1050                                 $item['body'] .= "\n[img]".$attach['url'].'[/img]';
1051                         } else {
1052                                 if (!empty($item["attach"])) {
1053                                         $item["attach"] .= ',';
1054                                 } else {
1055                                         $item["attach"] = '';
1056                                 }
1057                                 if (!isset($attach['length'])) {
1058                                         $attach['length'] = "0";
1059                                 }
1060                                 $item["attach"] .= '[attach]href="'.$attach['url'].'" length="'.$attach['length'].'" type="'.$attach['mediaType'].'" title="'.defaults($attach, 'name', '').'"[/attach]';
1061                         }
1062                 }
1063
1064                 return $item;
1065         }
1066
1067         private static function createItem($activity, $body)
1068         {
1069                 $item = [];
1070                 $item['verb'] = ACTIVITY_POST;
1071                 $item['parent-uri'] = $activity['reply-to-uri'];
1072
1073                 if ($activity['reply-to-uri'] == $activity['uri']) {
1074                         $item['gravity'] = GRAVITY_PARENT;
1075                         $item['object-type'] = ACTIVITY_OBJ_NOTE;
1076                 } else {
1077                         $item['gravity'] = GRAVITY_COMMENT;
1078                         $item['object-type'] = ACTIVITY_OBJ_COMMENT;
1079                 }
1080
1081                 if (($activity['uri'] != $activity['reply-to-uri']) && !Item::exists(['uri' => $activity['reply-to-uri']])) {
1082                         logger('Parent ' . $activity['reply-to-uri'] . ' not found. Try to refetch it.');
1083                         self::fetchMissingActivity($activity['reply-to-uri'], $activity);
1084                 }
1085
1086                 self::postItem($activity, $item, $body);
1087         }
1088
1089         private static function likeItem($activity, $body)
1090         {
1091                 $item = [];
1092                 $item['verb'] = ACTIVITY_LIKE;
1093                 $item['parent-uri'] = $activity['object'];
1094                 $item['gravity'] = GRAVITY_ACTIVITY;
1095                 $item['object-type'] = ACTIVITY_OBJ_NOTE;
1096
1097                 self::postItem($activity, $item, $body);
1098         }
1099
1100         private static function postItem($activity, $item, $body)
1101         {
1102                 /// @todo What to do with $activity['context']?
1103
1104                 $item['network'] = Protocol::ACTIVITYPUB;
1105                 $item['private'] = !in_array(0, $activity['receiver']);
1106                 $item['author-id'] = Contact::getIdForURL($activity['author'], 0, true);
1107                 $item['owner-id'] = Contact::getIdForURL($activity['owner'], 0, true);
1108                 $item['uri'] = $activity['uri'];
1109                 $item['created'] = $activity['published'];
1110                 $item['edited'] = $activity['updated'];
1111                 $item['guid'] = $activity['uuid'];
1112                 $item['title'] = HTML::toBBCode($activity['name']);
1113                 $item['content-warning'] = HTML::toBBCode($activity['summary']);
1114                 $item['body'] = self::convertMentions(HTML::toBBCode($activity['content']));
1115                 $item['location'] = $activity['location'];
1116                 $item['tag'] = self::constructTagList($activity['tags'], $activity['sensitive']);
1117                 $item['app'] = $activity['service'];
1118                 $item['plink'] = defaults($activity, 'alternate-url', $item['uri']);
1119
1120                 $item = self::constructAttachList($activity['attachments'], $item);
1121
1122                 $source = self::processElement($activity, 'source', 'content', 'mediaType', 'text/bbcode');
1123                 if (!empty($source)) {
1124                         $item['body'] = $source;
1125                 }
1126
1127                 $item['protocol'] = Conversation::PARCEL_ACTIVITYPUB;
1128                 $item['source'] = $body;
1129                 $item['conversation-uri'] = $activity['conversation'];
1130
1131                 foreach ($activity['receiver'] as $receiver) {
1132                         $item['uid'] = $receiver;
1133                         $item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver, true);
1134
1135                         if (($receiver != 0) && empty($item['contact-id'])) {
1136                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], 0, true);
1137                         }
1138
1139                         $item_id = Item::insert($item);
1140                         logger('Storing for user ' . $item['uid'] . ': ' . $item_id);
1141                 }
1142         }
1143
1144         private static function fetchMissingActivity($url, $child)
1145         {
1146                 $object = ActivityPub::fetchContent($url);
1147                 if (empty($object)) {
1148                         logger('Activity ' . $url . ' was not fetchable, aborting.');
1149                         return;
1150                 }
1151
1152                 $activity = [];
1153                 $activity['@context'] = $object['@context'];
1154                 unset($object['@context']);
1155                 $activity['id'] = $object['id'];
1156                 $activity['to'] = defaults($object, 'to', []);
1157                 $activity['cc'] = defaults($object, 'cc', []);
1158                 $activity['actor'] = $activity['author'];
1159                 $activity['object'] = $object;
1160                 $activity['published'] = $object['published'];
1161                 $activity['type'] = 'Create';
1162                 self::processActivity($activity);
1163                 logger('Activity ' . $url . ' had been fetched and processed.');
1164         }
1165
1166         private static function getUserOfObject($object)
1167         {
1168                 $self = DBA::selectFirst('contact', ['uid'], ['nurl' => normalise_link($object), 'self' => true]);
1169                 if (!DBA::isResult($self)) {
1170                         return false;
1171                 } else {
1172                         return $self['uid'];
1173                 }
1174         }
1175
1176         private static function followUser($activity)
1177         {
1178                 $uid = self::getUserOfObject($activity['object']);
1179                 if (empty($uid)) {
1180                         return;
1181                 }
1182
1183                 $owner = User::getOwnerDataById($uid);
1184
1185                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1186                 if (!empty($cid)) {
1187                         $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
1188                 } else {
1189                         $contact = false;
1190                 }
1191
1192                 $item = ['author-id' => Contact::getIdForURL($activity['owner']),
1193                         'author-link' => $activity['owner']];
1194
1195                 Contact::addRelationship($owner, $contact, $item);
1196                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1197                 if (empty($cid)) {
1198                         return;
1199                 }
1200
1201                 $contact = DBA::selectFirst('contact', ['network'], ['id' => $cid]);
1202                 if ($contact['network'] != Protocol::ACTIVITYPUB) {
1203                         Contact::updateFromProbe($cid, Protocol::ACTIVITYPUB);
1204                 }
1205
1206                 DBA::update('contact', ['hub-verify' => $activity['id']], ['id' => $cid]);
1207                 logger('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
1208         }
1209
1210         private static function acceptFollowUser($activity)
1211         {
1212                 $uid = self::getUserOfObject($activity['object']);
1213                 if (empty($uid)) {
1214                         return;
1215                 }
1216
1217                 $owner = User::getOwnerDataById($uid);
1218
1219                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1220                 if (empty($cid)) {
1221                         logger('No contact found for ' . $activity['owner'], LOGGER_DEBUG);
1222                         return;
1223                 }
1224
1225                 $fields = ['pending' => false];
1226
1227                 $contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
1228                 if ($contact['rel'] == Contact::FOLLOWER) {
1229                         $fields['rel'] = Contact::FRIEND;
1230                 }
1231
1232                 $condition = ['id' => $cid];
1233                 DBA::update('contact', $fields, $condition);
1234                 logger('Accept contact request from contact ' . $cid . ' for user ' . $uid, LOGGER_DEBUG);
1235         }
1236
1237         private static function undoFollowUser($activity)
1238         {
1239                 $uid = self::getUserOfObject($activity['object']);
1240                 if (empty($uid)) {
1241                         return;
1242                 }
1243
1244                 $owner = User::getOwnerDataById($uid);
1245
1246                 $cid = Contact::getIdForURL($activity['owner'], $uid);
1247                 if (empty($cid)) {
1248                         logger('No contact found for ' . $activity['owner'], LOGGER_DEBUG);
1249                         return;
1250                 }
1251
1252                 $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
1253                 if (!DBA::isResult($contact)) {
1254                         return;
1255                 }
1256
1257                 Contact::removeFollower($owner, $contact);
1258                 logger('Undo following request from contact ' . $cid . ' for user ' . $uid, LOGGER_DEBUG);
1259         }
1260 }