src/Protocol/ActivityPub.php

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