src/Protocol/ActivityPub/Processor.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2020, Friendica
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Protocol\ActivityPub;
  23
  24 use Friendica\Content\PageInfo;
  25 use Friendica\Content\Text\BBCode;
  26 use Friendica\Content\Text\HTML;
  27 use Friendica\Core\Logger;
  28 use Friendica\Core\Protocol;
  29 use Friendica\Database\DBA;
  30 use Friendica\DI;
  31 use Friendica\Model\APContact;
  32 use Friendica\Model\Contact;
  33 use Friendica\Model\Conversation;
  34 use Friendica\Model\Event;
  35 use Friendica\Model\Item;
  36 use Friendica\Model\ItemURI;
  37 use Friendica\Model\Mail;
  38 use Friendica\Model\Tag;
  39 use Friendica\Model\User;
  40 use Friendica\Protocol\Activity;
  41 use Friendica\Protocol\ActivityPub;
  42 use Friendica\Protocol\Relay;
  43 use Friendica\Util\DateTimeFormat;
  44 use Friendica\Util\JsonLD;
  45 use Friendica\Util\Strings;
  46
  47 /**
  48  * ActivityPub Processor Protocol class
  49  */
  50 class Processor
  51 {
  52         /**
  53          * Converts mentions from Pleroma into the Friendica format
  54          *
  55          * @param string $body
  56          *
  57          * @return string converted body
  58          */
  59         private static function convertMentions($body)
  60         {
  61                 $URLSearchString = "^\[\]";
  62                 $body = preg_replace("/\[url\=([$URLSearchString]*)\]([#@!])(.*?)\[\/url\]/ism", '$2[url=$1]$3[/url]', $body);
  63
  64                 return $body;
  65         }
  66
  67         /**
  68          * Replaces emojis in the body
  69          *
  70          * @param array $emojis
  71          * @param string $body
  72          *
  73          * @return string with replaced emojis
  74          */
  75         private static function replaceEmojis($body, array $emojis)
  76         {
  77                 foreach ($emojis as $emoji) {
  78                         $replace = '[class=emoji mastodon][img=' . $emoji['href'] . ']' . $emoji['name'] . '[/img][/class]';
  79                         $body = str_replace($emoji['name'], $replace, $body);
  80                 }
  81                 return $body;
  82         }
  83
  84         /**
  85          * Add attachment data to the item array
  86          *
  87          * @param array   $activity
  88          * @param array   $item
  89          *
  90          * @return array array
  91          */
  92         private static function constructAttachList($activity, $item)
  93         {
  94                 if (empty($activity['attachments'])) {
  95                         return $item;
  96                 }
  97
  98                 foreach ($activity['attachments'] as $attach) {
  99                         switch ($attach['type']) {
 100                                 case 'link':
 101                                         $data = [
 102                                                 'url'      => $attach['url'],
 103                                                 'type'     => $attach['type'],
 104                                                 'title'    => $attach['title'] ?? '',
 105                                                 'text'     => $attach['desc']  ?? '',
 106                                                 'image'    => $attach['image'] ?? '',
 107                                                 'images'   => [],
 108                                                 'keywords' => [],
 109                                         ];
 110                                         $item['body'] = PageInfo::appendDataToBody($item['body'], $data);
 111                                         break;
 112                                 default:
 113                                         $filetype = strtolower(substr($attach['mediaType'], 0, strpos($attach['mediaType'], '/')));
 114                                         if ($filetype == 'image') {
 115                                                 if (!empty($activity['source']) && strpos($activity['source'], $attach['url'])) {
 116                                                         continue 2;
 117                                                 }
 118
 119                                                 $item['body'] .= "\n";
 120
 121                                                 // image is the preview/thumbnail URL
 122                                                 if (!empty($attach['image'])) {
 123                                                         $item['body'] .= '[url=' . $attach['url'] . ']';
 124                                                         $attach['url'] = $attach['image'];
 125                                                 }
 126
 127                                                 if (empty($attach['name'])) {
 128                                                         $item['body'] .= '[img]' . $attach['url'] . '[/img]';
 129                                                 } else {
 130                                                         $item['body'] .= '[img=' . $attach['url'] . ']' . $attach['name'] . '[/img]';
 131                                                 }
 132
 133                                                 if (!empty($attach['image'])) {
 134                                                         $item['body'] .= '[/url]';
 135                                                 }
 136                                         } elseif ($filetype == 'audio') {
 137                                                 if (!empty($activity['source']) && strpos($activity['source'], $attach['url'])) {
 138                                                         continue 2;
 139                                                 }
 140
 141                                                 $item['body'] .= "\n[audio]" . $attach['url'] . '[/audio]';
 142                                         } elseif ($filetype == 'video') {
 143                                                 if (!empty($activity['source']) && strpos($activity['source'], $attach['url'])) {
 144                                                         continue 2;
 145                                                 }
 146
 147                                                 $item['body'] .= "\n[video]" . $attach['url'] . '[/video]';
 148                                         } else {
 149                                                 if (!empty($item["attach"])) {
 150                                                         $item["attach"] .= ',';
 151                                                 } else {
 152                                                         $item["attach"] = '';
 153                                                 }
 154
 155                                                 $item["attach"] .= '[attach]href="' . $attach['url'] . '" length="' . ($attach['length'] ?? '0') . '" type="' . $attach['mediaType'] . '" title="' . ($attach['name'] ?? '') . '"[/attach]';
 156                                         }
 157                         }
 158                 }
 159
 160                 return $item;
 161         }
 162
 163         /**
 164          * Updates a message
 165          *
 166          * @param array $activity Activity array
 167          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 168          */
 169         public static function updateItem($activity)
 170         {
 171                 $item = Item::selectFirst(['uri', 'uri-id', 'thr-parent', 'gravity'], ['uri' => $activity['id']]);
 172                 if (!DBA::isResult($item)) {
 173                         Logger::warning('No existing item, item will be created', ['uri' => $activity['id']]);
 174                         $item = self::createItem($activity);
 175                         self::postItem($activity, $item);
 176                         return;
 177                 }
 178
 179                 $item['changed'] = DateTimeFormat::utcNow();
 180                 $item['edited'] = DateTimeFormat::utc($activity['updated']);
 181
 182                 $item = self::processContent($activity, $item);
 183                 if (empty($item)) {
 184                         return;
 185                 }
 186
 187                 Item::update($item, ['uri' => $activity['id']]);
 188         }
 189
 190         /**
 191          * Prepares data for a message
 192          *
 193          * @param array $activity Activity array
 194          * @return array Internal item
 195          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 196          * @throws \ImagickException
 197          */
 198         public static function createItem($activity)
 199         {
 200                 $item = [];
 201                 $item['verb'] = Activity::POST;
 202                 $item['thr-parent'] = $activity['reply-to-id'];
 203
 204                 if ($activity['reply-to-id'] == $activity['id']) {
 205                         $item['gravity'] = GRAVITY_PARENT;
 206                         $item['object-type'] = Activity\ObjectType::NOTE;
 207                 } else {
 208                         $item['gravity'] = GRAVITY_COMMENT;
 209                         $item['object-type'] = Activity\ObjectType::COMMENT;
 210                 }
 211
 212                 if (empty($activity['directmessage']) && ($activity['id'] != $activity['reply-to-id']) && !Item::exists(['uri' => $activity['reply-to-id']])) {
 213                         Logger::notice('Parent not found. Try to refetch it.', ['parent' => $activity['reply-to-id']]);
 214                         self::fetchMissingActivity($activity['reply-to-id'], $activity);
 215                 }
 216
 217                 $item['diaspora_signed_text'] = $activity['diaspora:comment'] ?? '';
 218
 219                 /// @todo What to do with $activity['context']?
 220                 if (empty($activity['directmessage']) && ($item['gravity'] != GRAVITY_PARENT) && !Item::exists(['uri' => $item['thr-parent']])) {
 221                         Logger::info('Parent not found, message will be discarded.', ['thr-parent' => $item['thr-parent']]);
 222                         return [];
 223                 }
 224
 225                 $item['network'] = Protocol::ACTIVITYPUB;
 226                 $item['author-link'] = $activity['author'];
 227                 $item['author-id'] = Contact::getIdForURL($activity['author']);
 228                 $item['owner-link'] = $activity['actor'];
 229                 $item['owner-id'] = Contact::getIdForURL($activity['actor']);
 230
 231                 if (in_array(0, $activity['receiver']) && !empty($activity['unlisted'])) {
 232                         $item['private'] = Item::UNLISTED;
 233                 } elseif (in_array(0, $activity['receiver'])) {
 234                         $item['private'] = Item::PUBLIC;
 235                 } else {
 236                         $item['private'] = Item::PRIVATE;
 237                 }
 238
 239                 if (!empty($activity['raw'])) {
 240                         $item['source'] = $activity['raw'];
 241                         $item['protocol'] = Conversation::PARCEL_ACTIVITYPUB;
 242                         $item['conversation-href'] = $activity['context'] ?? '';
 243                         $item['conversation-uri'] = $activity['conversation'] ?? '';
 244
 245                         if (isset($activity['push'])) {
 246                                 $item['direction'] = $activity['push'] ? Conversation::PUSH : Conversation::PULL;
 247                         }
 248                 }
 249
 250                 $item['isForum'] = false;
 251
 252                 if (!empty($activity['thread-completion'])) {
 253                         if ($activity['thread-completion'] != $item['owner-id']) {
 254                                 $actor = Contact::getById($activity['thread-completion'], ['url']);
 255                                 $item['causer-link'] = $actor['url'];
 256                                 $item['causer-id'] = $activity['thread-completion'];
 257                                 Logger::info('Use inherited actor as causer.', ['id' => $item['owner-id'], 'activity' => $activity['thread-completion'], 'owner' => $item['owner-link'], 'actor' => $actor['url']]);
 258                         } else {
 259                                 // Store the original actor in the "causer" fields to enable the check for ignored or blocked contacts
 260                                 $item['causer-link'] = $item['owner-link'];
 261                                 $item['causer-id'] = $item['owner-id'];
 262                                 Logger::info('Use actor as causer.', ['id' => $item['owner-id'], 'actor' => $item['owner-link']]);
 263                         }
 264
 265                         $item['owner-link'] = $item['author-link'];
 266                         $item['owner-id'] = $item['author-id'];
 267                 } else {
 268                         $actor = APContact::getByURL($item['owner-link'], false);
 269                         $item['isForum'] = ($actor['type'] == 'Group');
 270                 }
 271
 272                 $item['uri'] = $activity['id'];
 273
 274                 $item['created'] = DateTimeFormat::utc($activity['published']);
 275                 $item['edited'] = DateTimeFormat::utc($activity['updated']);
 276                 $guid = $activity['sc:identifier'] ?: self::getGUIDByURL($item['uri']);
 277                 $item['guid'] = $activity['diaspora:guid'] ?: $guid;
 278
 279                 $item['uri-id'] = ItemURI::insert(['uri' => $item['uri'], 'guid' => $item['guid']]);
 280
 281                 $item = self::processContent($activity, $item);
 282                 if (empty($item)) {
 283                         Logger::info('Message was not processed');
 284                         return [];
 285                 }
 286
 287                 $item['plink'] = $activity['alternate-url'] ?? $item['uri'];
 288
 289                 $item = self::constructAttachList($activity, $item);
 290
 291                 return $item;
 292         }
 293
 294         /**
 295          * Delete items
 296          *
 297          * @param array $activity
 298          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 299          * @throws \ImagickException
 300          */
 301         public static function deleteItem($activity)
 302         {
 303                 $owner = Contact::getIdForURL($activity['actor']);
 304
 305                 Logger::info('Deleting item', ['object' => $activity['object_id'], 'owner'  => $owner]);
 306                 Item::markForDeletion(['uri' => $activity['object_id'], 'owner-id' => $owner]);
 307         }
 308
 309         /**
 310          * Prepare the item array for an activity
 311          *
 312          * @param array $activity Activity array
 313          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 314          * @throws \ImagickException
 315          */
 316         public static function addTag($activity)
 317         {
 318                 if (empty($activity['object_content']) || empty($activity['object_id'])) {
 319                         return;
 320                 }
 321
 322                 foreach ($activity['receiver'] as $receiver) {
 323                         $item = Item::selectFirst(['id', 'uri-id', 'tag', 'origin', 'author-link'], ['uri' => $activity['target_id'], 'uid' => $receiver]);
 324                         if (!DBA::isResult($item)) {
 325                                 // We don't fetch missing content for this purpose
 326                                 continue;
 327                         }
 328
 329                         if (($item['author-link'] != $activity['actor']) && !$item['origin']) {
 330                                 Logger::info('Not origin, not from the author, skipping update', ['id' => $item['id'], 'author' => $item['author-link'], 'actor' => $activity['actor']]);
 331                                 continue;
 332                         }
 333
 334                         Tag::store($item['uri-id'], Tag::HASHTAG, $activity['object_content'], $activity['object_id']);
 335                         Logger::info('Tagged item', ['id' => $item['id'], 'tag' => $activity['object_content'], 'uri' => $activity['target_id'], 'actor' => $activity['actor']]);
 336                 }
 337         }
 338
 339         /**
 340          * Prepare the item array for an activity
 341          *
 342          * @param array  $activity Activity array
 343          * @param string $verb     Activity verb
 344          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 345          * @throws \ImagickException
 346          */
 347         public static function createActivity($activity, $verb)
 348         {
 349                 $item = self::createItem($activity);
 350                 $item['verb'] = $verb;
 351                 $item['thr-parent'] = $activity['object_id'];
 352                 $item['gravity'] = GRAVITY_ACTIVITY;
 353                 $item['object-type'] = Activity\ObjectType::NOTE;
 354
 355                 $item['diaspora_signed_text'] = $activity['diaspora:like'] ?? '';
 356
 357                 self::postItem($activity, $item);
 358         }
 359
 360         /**
 361          * Create an event
 362          *
 363          * @param array $activity Activity array
 364          * @param array $item
 365          * @throws \Exception
 366          */
 367         public static function createEvent($activity, $item)
 368         {
 369                 $event['summary']  = HTML::toBBCode($activity['name']);
 370                 $event['desc']     = HTML::toBBCode($activity['content']);
 371                 $event['start']    = $activity['start-time'];
 372                 $event['finish']   = $activity['end-time'];
 373                 $event['nofinish'] = empty($event['finish']);
 374                 $event['location'] = $activity['location'];
 375                 $event['adjust']   = true;
 376                 $event['cid']      = $item['contact-id'];
 377                 $event['uid']      = $item['uid'];
 378                 $event['uri']      = $item['uri'];
 379                 $event['edited']   = $item['edited'];
 380                 $event['private']  = $item['private'];
 381                 $event['guid']     = $item['guid'];
 382                 $event['plink']    = $item['plink'];
 383
 384                 $condition = ['uri' => $item['uri'], 'uid' => $item['uid']];
 385                 $ev = DBA::selectFirst('event', ['id'], $condition);
 386                 if (DBA::isResult($ev)) {
 387                         $event['id'] = $ev['id'];
 388                 }
 389
 390                 $event_id = Event::store($event);
 391                 Logger::info('Event was stored', ['id' => $event_id]);
 392         }
 393
 394         /**
 395          * Process the content
 396          *
 397          * @param array $activity Activity array
 398          * @param array $item
 399          * @return array|bool Returns the item array or false if there was an unexpected occurrence
 400          * @throws \Exception
 401          */
 402         private static function processContent($activity, $item)
 403         {
 404                 $item['title'] = HTML::toBBCode($activity['name']);
 405
 406                 if (!empty($activity['source'])) {
 407                         $item['body'] = $activity['source'];
 408                 } else {
 409                         $content = HTML::toBBCode($activity['content']);
 410
 411                         if (!empty($activity['emojis'])) {
 412                                 $content = self::replaceEmojis($content, $activity['emojis']);
 413                         }
 414
 415                         $content = self::convertMentions($content);
 416
 417                         if (empty($activity['directmessage']) && ($item['thr-parent'] != $item['uri']) && ($item['gravity'] == GRAVITY_COMMENT)) {
 418                                 $item_private = !in_array(0, $activity['item_receiver']);
 419                                 $parent = Item::selectFirst(['id', 'uri-id', 'private', 'author-link', 'alias'], ['uri' => $item['thr-parent']]);
 420                                 if (!DBA::isResult($parent)) {
 421                                         Logger::warning('Unknown parent item.', ['uri' => $item['thr-parent']]);
 422                                         return false;
 423                                 }
 424                                 if ($item_private && ($parent['private'] != Item::PRIVATE)) {
 425                                         Logger::warning('Item is private but the parent is not. Dropping.', ['item-uri' => $item['uri'], 'thr-parent' => $item['thr-parent']]);
 426                                         return false;
 427                                 }
 428
 429                                 $content = self::removeImplicitMentionsFromBody($content, $parent);
 430                         }
 431                         $item['content-warning'] = HTML::toBBCode($activity['summary']);
 432                         $item['body'] = $content;
 433                 }
 434
 435                 self::storeFromBody($item);
 436                 self::storeTags($item['uri-id'], $activity['tags']);
 437
 438                 $item['location'] = $activity['location'];
 439
 440                 if (!empty($activity['latitude']) && !empty($activity['longitude'])) {
 441                         $item['coord'] = $activity['latitude'] . ' ' . $activity['longitude'];
 442                 }
 443
 444                 $item['app'] = $activity['generator'];
 445
 446                 return $item;
 447         }
 448
 449         /**
 450          * Store hashtags and mentions
 451          *
 452          * @param array $item
 453          */
 454         private static function storeFromBody(array $item)
 455         {
 456                 // Make sure to delete all existing tags (can happen when called via the update functionality)
 457                 DBA::delete('post-tag', ['uri-id' => $item['uri-id']]);
 458
 459                 Tag::storeFromBody($item['uri-id'], $item['body'], '@!');
 460         }
 461
 462         /**
 463          * Generate a GUID out of an URL
 464          *
 465          * @param string $url message URL
 466          * @return string with GUID
 467          */
 468         private static function getGUIDByURL(string $url)
 469         {
 470                 $parsed = parse_url($url);
 471
 472                 $host_hash = hash('crc32', $parsed['host']);
 473
 474                 unset($parsed["scheme"]);
 475                 unset($parsed["host"]);
 476
 477                 $path = implode("/", $parsed);
 478
 479                 return $host_hash . '-'. hash('fnv164', $path) . '-'. hash('joaat', $path);
 480         }
 481
 482         /**
 483          * Creates an item post
 484          *
 485          * @param array $activity Activity data
 486          * @param array $item     item array
 487          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 488          * @throws \ImagickException
 489          */
 490         public static function postItem(array $activity, array $item)
 491         {
 492                 if (empty($item)) {
 493                         return;
 494                 }
 495
 496                 $stored = false;
 497                 ksort($activity['receiver']);
 498
 499                 foreach ($activity['receiver'] as $receiver) {
 500                         if ($receiver == -1) {
 501                                 continue;
 502                         }
 503
 504                         $item['uid'] = $receiver;
 505
 506                         $type = $activity['reception_type'][$receiver] ?? Receiver::TARGET_UNKNOWN;
 507                         switch($type) {
 508                                 case Receiver::TARGET_TO:
 509                                         $item['post-type'] = Item::PT_TO;
 510                                         break;
 511                                 case Receiver::TARGET_CC:
 512                                         $item['post-type'] = Item::PT_CC;
 513                                         break;
 514                                 case Receiver::TARGET_BTO:
 515                                         $item['post-type'] = Item::PT_BTO;
 516                                         break;
 517                                 case Receiver::TARGET_BCC:
 518                                         $item['post-type'] = Item::PT_BCC;
 519                                         break;
 520                                 case Receiver::TARGET_FOLLOWER:
 521                                         $item['post-type'] = Item::PT_FOLLOWER;
 522                                         break;
 523                                 case Receiver::TARGET_ANSWER:
 524                                         $item['post-type'] = Item::PT_COMMENT;
 525                                         break;
 526                                 case Receiver::TARGET_GLOBAL:
 527                                         $item['post-type'] = Item::PT_GLOBAL;
 528                                         break;
 529                                 default:
 530                                         $item['post-type'] = Item::PT_ARTICLE;
 531                         }
 532
 533                         if (!empty($activity['from-relay'])) {
 534                                 $item['post-type'] = Item::PT_RELAY;
 535                         } elseif (!empty($activity['thread-completion'])) {
 536                                 $item['post-type'] = Item::PT_FETCHED;
 537                         }
 538
 539                         if ($item['isForum'] ?? false) {
 540                                 $item['contact-id'] = Contact::getIdForURL($activity['actor'], $receiver);
 541                         } else {
 542                                 $item['contact-id'] = Contact::getIdForURL($activity['author'], $receiver);
 543                         }
 544
 545                         if (($receiver != 0) && empty($item['contact-id'])) {
 546                                 $item['contact-id'] = Contact::getIdForURL($activity['author']);
 547                         }
 548
 549                         if (!empty($activity['directmessage'])) {
 550                                 self::postMail($activity, $item);
 551                                 continue;
 552                         }
 553
 554                         if (DI::pConfig()->get($receiver, 'system', 'accept_only_sharer', false) && ($receiver != 0) && ($item['gravity'] == GRAVITY_PARENT)) {
 555                                 $skip = !Contact::isSharingByURL($activity['author'], $receiver);
 556
 557                                 if ($skip && (($activity['type'] == 'as:Announce') || ($item['isForum'] ?? false))) {
 558                                         $skip = !Contact::isSharingByURL($activity['actor'], $receiver);
 559                                 }
 560
 561                                 if ($skip) {
 562                                         Logger::info('Skipping post', ['uid' => $receiver, 'url' => $item['uri']]);
 563                                         continue;
 564                                 }
 565
 566                                 Logger::info('Accepting post', ['uid' => $receiver, 'url' => $item['uri']]);
 567                         }
 568
 569                         if (($item['gravity'] != GRAVITY_ACTIVITY) && ($activity['object_type'] == 'as:Event')) {
 570                                 self::createEvent($activity, $item);
 571                         }
 572
 573                         $item_id = Item::insert($item);
 574                         if ($item_id) {
 575                                 Logger::info('Item insertion successful', ['user' => $item['uid'], 'item_id' => $item_id]);
 576                         } else {
 577                                 Logger::notice('Item insertion aborted', ['user' => $item['uid']]);
 578                         }
 579
 580                         if ($item['uid'] == 0) {
 581                                 $stored = $item_id;
 582                         }
 583                 }
 584
 585                 // Store send a follow request for every reshare - but only when the item had been stored
 586                 if ($stored && ($item['private'] != Item::PRIVATE) && ($item['gravity'] == GRAVITY_PARENT) && ($item['author-link'] != $item['owner-link'])) {
 587                         $author = APContact::getByURL($item['owner-link'], false);
 588                         // We send automatic follow requests for reshared messages. (We don't need though for forum posts)
 589                         if ($author['type'] != 'Group') {
 590                                 Logger::info('Send follow request', ['uri' => $item['uri'], 'stored' => $stored, 'to' => $item['author-link']]);
 591                                 ActivityPub\Transmitter::sendFollowObject($item['uri'], $item['author-link']);
 592                         }
 593                 }
 594         }
 595
 596         /**
 597          * Store tags and mentions into the tag table
 598          *
 599          * @param integer $uriid
 600          * @param array $tags
 601          */
 602         private static function storeTags(int $uriid, array $tags = null)
 603         {
 604                 foreach ($tags as $tag) {
 605                         if (empty($tag['name']) || empty($tag['type']) || !in_array($tag['type'], ['Mention', 'Hashtag'])) {
 606                                 continue;
 607                         }
 608
 609                         $hash = substr($tag['name'], 0, 1);
 610
 611                         if ($tag['type'] == 'Mention') {
 612                                 if (in_array($hash, [Tag::TAG_CHARACTER[Tag::MENTION],
 613                                         Tag::TAG_CHARACTER[Tag::EXCLUSIVE_MENTION],
 614                                         Tag::TAG_CHARACTER[Tag::IMPLICIT_MENTION]])) {
 615                                         $tag['name'] = substr($tag['name'], 1);
 616                                 }
 617                                 $type = Tag::IMPLICIT_MENTION;
 618
 619                                 if (!empty($tag['href'])) {
 620                                         $apcontact = APContact::getByURL($tag['href']);
 621                                         if (!empty($apcontact['name']) || !empty($apcontact['nick'])) {
 622                                                 $tag['name'] = $apcontact['name'] ?: $apcontact['nick'];
 623                                         }
 624                                 }
 625                         } elseif ($tag['type'] == 'Hashtag') {
 626                                 if ($hash == Tag::TAG_CHARACTER[Tag::HASHTAG]) {
 627                                         $tag['name'] = substr($tag['name'], 1);
 628                                 }
 629                                 $type = Tag::HASHTAG;
 630                         }
 631
 632                         if (empty($tag['name'])) {
 633                                 continue;
 634                         }
 635
 636                         Tag::store($uriid, $type, $tag['name'], $tag['href']);
 637                 }
 638         }
 639
 640         /**
 641          * Creates an mail post
 642          *
 643          * @param array $activity Activity data
 644          * @param array $item     item array
 645          * @return int|bool New mail table row id or false on error
 646          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 647          */
 648         private static function postMail($activity, $item)
 649         {
 650                 if (($item['gravity'] != GRAVITY_PARENT) && !DBA::exists('mail', ['uri' => $item['thr-parent'], 'uid' => $item['uid']])) {
 651                         Logger::info('Parent not found, mail will be discarded.', ['uid' => $item['uid'], 'uri' => $item['thr-parent']]);
 652                         return false;
 653                 }
 654
 655                 Logger::info('Direct Message', $item);
 656
 657                 $msg = [];
 658                 $msg['uid'] = $item['uid'];
 659
 660                 $msg['contact-id'] = $item['contact-id'];
 661
 662                 $contact = Contact::getById($item['contact-id'], ['name', 'url', 'photo']);
 663                 $msg['from-name'] = $contact['name'];
 664                 $msg['from-url'] = $contact['url'];
 665                 $msg['from-photo'] = $contact['photo'];
 666
 667                 $msg['uri'] = $item['uri'];
 668                 $msg['created'] = $item['created'];
 669
 670                 $parent = DBA::selectFirst('mail', ['parent-uri', 'title'], ['uri' => $item['thr-parent']]);
 671                 if (DBA::isResult($parent)) {
 672                         $msg['parent-uri'] = $parent['parent-uri'];
 673                         $msg['title'] = $parent['title'];
 674                 } else {
 675                         $msg['parent-uri'] = $item['thr-parent'];
 676
 677                         if (!empty($item['title'])) {
 678                                 $msg['title'] = $item['title'];
 679                         } elseif (!empty($item['content-warning'])) {
 680                                 $msg['title'] = $item['content-warning'];
 681                         } else {
 682                                 // Trying to generate a title out of the body
 683                                 $title = $item['body'];
 684
 685                                 while (preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $title, $matches)) {
 686                                         $title = $matches[3];
 687                                 }
 688
 689                                 $title = trim(HTML::toPlaintext(BBCode::convert($title, false, BBCode::API, true), 0));
 690
 691                                 if (strlen($title) > 20) {
 692                                         $title = substr($title, 0, 20) . '...';
 693                                 }
 694
 695                                 $msg['title'] = $title;
 696                         }
 697                 }
 698                 $msg['body'] = $item['body'];
 699
 700                 return Mail::insert($msg);
 701         }
 702
 703         /**
 704          * Fetches missing posts
 705          *
 706          * @param string $url         message URL
 707          * @param array  $child       activity array with the child of this message
 708          * @param string $relay_actor Relay actor
 709          * @return string fetched message URL
 710          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 711          */
 712         public static function fetchMissingActivity(string $url, array $child = [], string $relay_actor = '')
 713         {
 714                 if (!empty($child['receiver'])) {
 715                         $uid = ActivityPub\Receiver::getFirstUserFromReceivers($child['receiver']);
 716                 } else {
 717                         $uid = 0;
 718                 }
 719
 720                 $object = ActivityPub::fetchContent($url, $uid);
 721                 if (empty($object)) {
 722                         Logger::log('Activity ' . $url . ' was not fetchable, aborting.');
 723                         return '';
 724                 }
 725
 726                 if (empty($object['id'])) {
 727                         Logger::log('Activity ' . $url . ' has got not id, aborting. ' . json_encode($object));
 728                         return '';
 729                 }
 730
 731                 if (!empty($object['actor'])) {
 732                         $object_actor = $object['actor'];
 733                 } elseif (!empty($object['attributedTo'])) {
 734                         $object_actor = $object['attributedTo'];
 735                 } else {
 736                         // Shouldn't happen
 737                         $object_actor = '';
 738                 }
 739
 740                 $signer = [$object_actor];
 741
 742                 if (!empty($child['author'])) {
 743                         $actor = $child['author'];
 744                         $signer[] = $actor;
 745                 } else {
 746                         $actor = $object_actor;
 747                 }
 748
 749                 if (!empty($object['published'])) {
 750                         $published = $object['published'];
 751                 } elseif (!empty($child['published'])) {
 752                         $published = $child['published'];
 753                 } else {
 754                         $published = DateTimeFormat::utcNow();
 755                 }
 756
 757                 $activity = [];
 758                 $activity['@context'] = $object['@context'];
 759                 unset($object['@context']);
 760                 $activity['id'] = $object['id'];
 761                 $activity['to'] = $object['to'] ?? [];
 762                 $activity['cc'] = $object['cc'] ?? [];
 763                 $activity['actor'] = $actor;
 764                 $activity['object'] = $object;
 765                 $activity['published'] = $published;
 766                 $activity['type'] = 'Create';
 767
 768                 $ldactivity = JsonLD::compact($activity);
 769
 770                 if (!empty($relay_actor)) {
 771                         $ldactivity['thread-completion'] = $ldactivity['from-relay'] = Contact::getIdForURL($relay_actor);
 772                 } elseif (!empty($child['thread-completion'])) {
 773                         $ldactivity['thread-completion'] = $child['thread-completion'];
 774                 } else {
 775                         $ldactivity['thread-completion'] = Contact::getIdForURL($actor);
 776                 }
 777
 778                 if (!empty($relay_actor) && !self::acceptIncomingMessage($ldactivity, $object['id'])) {
 779                         return '';
 780                 }
 781
 782                 ActivityPub\Receiver::processActivity($ldactivity, json_encode($activity), $uid, true, false, $signer);
 783
 784                 Logger::notice('Activity had been fetched and processed.', ['url' => $url, 'object' => $activity['id']]);
 785
 786                 return $activity['id'];
 787         }
 788
 789         /**
 790          * Test if incoming relay messages should be accepted
 791          *
 792          * @param array $activity activity array
 793          * @param string $id      object ID
 794          * @return boolean true if message is accepted
 795          */
 796         private static function acceptIncomingMessage(array $activity, string $id)
 797         {
 798                 if (empty($activity['as:object'])) {
 799                         Logger::info('No object field in activity - accepted', ['id' => $id]);
 800                         return true;
 801                 }
 802
 803                 $replyto = JsonLD::fetchElement($activity['as:object'], 'as:inReplyTo', '@id');
 804                 if (Item::exists(['uri' => $replyto])) {
 805                         Logger::info('Post is a reply to an existing post - accepted', ['id' => $id, 'replyto' => $replyto]);
 806                         return true;
 807                 }
 808
 809                 $body = HTML::toBBCode(JsonLD::fetchElement($activity['as:object'], 'as:content', '@value'));
 810
 811                 $messageTags = [];
 812                 $tags = Receiver::processTags(JsonLD::fetchElementArray($activity['as:object'], 'as:tag') ?? []);
 813                 if (!empty($tags)) {
 814                         foreach ($tags as $tag) {
 815                                 if ($tag['type'] != 'Hashtag') {
 816                                         continue;
 817                                 }
 818                                 $messageTags[] = ltrim(mb_strtolower($tag['name']), '#');
 819                         }
 820                 }
 821
 822                 return Relay::isSolicitedPost($messageTags, $body, $id, Protocol::ACTIVITYPUB);
 823         }
 824
 825         /**
 826          * perform a "follow" request
 827          *
 828          * @param array $activity
 829          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 830          * @throws \ImagickException
 831          */
 832         public static function followUser($activity)
 833         {
 834                 $uid = User::getIdForURL($activity['object_id']);
 835                 if (empty($uid)) {
 836                         return;
 837                 }
 838
 839                 $owner = User::getOwnerDataById($uid);
 840                 if (empty($owner)) {
 841                         return;
 842                 }
 843
 844                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 845                 if (!empty($cid)) {
 846                         self::switchContact($cid);
 847                         DBA::update('contact', ['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
 848                         $contact = DBA::selectFirst('contact', [], ['id' => $cid, 'network' => Protocol::NATIVE_SUPPORT]);
 849                 } else {
 850                         $contact = [];
 851                 }
 852
 853                 $item = ['author-id' => Contact::getIdForURL($activity['actor']),
 854                         'author-link' => $activity['actor']];
 855
 856                 $note = Strings::escapeTags(trim($activity['content'] ?? ''));
 857
 858                 // Ensure that the contact has got the right network type
 859                 self::switchContact($item['author-id']);
 860
 861                 $result = Contact::addRelationship($owner, $contact, $item, false, $note);
 862                 if ($result === true) {
 863                         ActivityPub\Transmitter::sendContactAccept($item['author-link'], $activity['id'], $owner['uid']);
 864                 }
 865
 866                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 867                 if (empty($cid)) {
 868                         return;
 869                 }
 870
 871                 if (empty($contact)) {
 872                         DBA::update('contact', ['hub-verify' => $activity['id'], 'protocol' => Protocol::ACTIVITYPUB], ['id' => $cid]);
 873                 }
 874
 875                 Logger::log('Follow user ' . $uid . ' from contact ' . $cid . ' with id ' . $activity['id']);
 876         }
 877
 878         /**
 879          * Update the given profile
 880          *
 881          * @param array $activity
 882          * @throws \Exception
 883          */
 884         public static function updatePerson($activity)
 885         {
 886                 if (empty($activity['object_id'])) {
 887                         return;
 888                 }
 889
 890                 Logger::info('Updating profile', ['object' => $activity['object_id']]);
 891                 Contact::updateFromProbeByURL($activity['object_id']);
 892         }
 893
 894         /**
 895          * Delete the given profile
 896          *
 897          * @param array $activity
 898          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 899          */
 900         public static function deletePerson($activity)
 901         {
 902                 if (empty($activity['object_id']) || empty($activity['actor'])) {
 903                         Logger::info('Empty object id or actor.');
 904                         return;
 905                 }
 906
 907                 if ($activity['object_id'] != $activity['actor']) {
 908                         Logger::info('Object id does not match actor.');
 909                         return;
 910                 }
 911
 912                 $contacts = DBA::select('contact', ['id'], ['nurl' => Strings::normaliseLink($activity['object_id'])]);
 913                 while ($contact = DBA::fetch($contacts)) {
 914                         Contact::remove($contact['id']);
 915                 }
 916                 DBA::close($contacts);
 917
 918                 Logger::info('Deleted contact', ['object' => $activity['object_id']]);
 919         }
 920
 921         /**
 922          * Accept a follow request
 923          *
 924          * @param array $activity
 925          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 926          * @throws \ImagickException
 927          */
 928         public static function acceptFollowUser($activity)
 929         {
 930                 $uid = User::getIdForURL($activity['object_actor']);
 931                 if (empty($uid)) {
 932                         return;
 933                 }
 934
 935                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 936                 if (empty($cid)) {
 937                         Logger::info('No contact found', ['actor' => $activity['actor']]);
 938                         return;
 939                 }
 940
 941                 self::switchContact($cid);
 942
 943                 $fields = ['pending' => false];
 944
 945                 $contact = DBA::selectFirst('contact', ['rel'], ['id' => $cid]);
 946                 if ($contact['rel'] == Contact::FOLLOWER) {
 947                         $fields['rel'] = Contact::FRIEND;
 948                 }
 949
 950                 $condition = ['id' => $cid];
 951                 DBA::update('contact', $fields, $condition);
 952                 Logger::info('Accept contact request', ['contact' => $cid, 'user' => $uid]);
 953         }
 954
 955         /**
 956          * Reject a follow request
 957          *
 958          * @param array $activity
 959          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 960          * @throws \ImagickException
 961          */
 962         public static function rejectFollowUser($activity)
 963         {
 964                 $uid = User::getIdForURL($activity['object_actor']);
 965                 if (empty($uid)) {
 966                         return;
 967                 }
 968
 969                 $cid = Contact::getIdForURL($activity['actor'], $uid);
 970                 if (empty($cid)) {
 971                         Logger::info('No contact found', ['actor' => $activity['actor']]);
 972                         return;
 973                 }
 974
 975                 self::switchContact($cid);
 976
 977                 if (DBA::exists('contact', ['id' => $cid, 'rel' => Contact::SHARING])) {
 978                         Contact::remove($cid);
 979                         Logger::info('Rejected contact request - contact removed', ['contact' => $cid, 'user' => $uid]);
 980                 } else {
 981                         Logger::info('Rejected contact request', ['contact' => $cid, 'user' => $uid]);
 982                 }
 983         }
 984
 985         /**
 986          * Undo activity like "like" or "dislike"
 987          *
 988          * @param array $activity
 989          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 990          * @throws \ImagickException
 991          */
 992         public static function undoActivity($activity)
 993         {
 994                 if (empty($activity['object_id'])) {
 995                         return;
 996                 }
 997
 998                 if (empty($activity['object_actor'])) {
 999                         return;
1000                 }
1001
1002                 $author_id = Contact::getIdForURL($activity['object_actor']);
1003                 if (empty($author_id)) {
1004                         return;
1005                 }
1006
1007                 Item::markForDeletion(['uri' => $activity['object_id'], 'author-id' => $author_id, 'gravity' => GRAVITY_ACTIVITY]);
1008         }
1009
1010         /**
1011          * Activity to remove a follower
1012          *
1013          * @param array $activity
1014          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1015          * @throws \ImagickException
1016          */
1017         public static function undoFollowUser($activity)
1018         {
1019                 $uid = User::getIdForURL($activity['object_object']);
1020                 if (empty($uid)) {
1021                         return;
1022                 }
1023
1024                 $owner = User::getOwnerDataById($uid);
1025                 if (empty($owner)) {
1026                         return;
1027                 }
1028
1029                 $cid = Contact::getIdForURL($activity['actor'], $uid);
1030                 if (empty($cid)) {
1031                         Logger::info('No contact found', ['actor' => $activity['actor']]);
1032                         return;
1033                 }
1034
1035                 self::switchContact($cid);
1036
1037                 $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
1038                 if (!DBA::isResult($contact)) {
1039                         return;
1040                 }
1041
1042                 Contact::removeFollower($owner, $contact);
1043                 Logger::info('Undo following request', ['contact' => $cid, 'user' => $uid]);
1044         }
1045
1046         /**
1047          * Switches a contact to AP if needed
1048          *
1049          * @param integer $cid Contact ID
1050          * @throws \Exception
1051          */
1052         private static function switchContact($cid)
1053         {
1054                 $contact = DBA::selectFirst('contact', ['network', 'url'], ['id' => $cid]);
1055                 if (!DBA::isResult($contact) || in_array($contact['network'], [Protocol::ACTIVITYPUB, Protocol::DFRN]) || Contact::isLocal($contact['url'])) {
1056                         return;
1057                 }
1058
1059                 Logger::info('Change existing contact', ['cid' => $cid, 'previous' => $contact['network']]);
1060                 Contact::updateFromProbe($cid);
1061         }
1062
1063         /**
1064          * Collects implicit mentions like:
1065          * - the author of the parent item
1066          * - all the mentioned conversants in the parent item
1067          *
1068          * @param array $parent Item array with at least ['id', 'author-link', 'alias']
1069          * @return array
1070          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
1071          */
1072         private static function getImplicitMentionList(array $parent)
1073         {
1074                 $parent_terms = Tag::getByURIId($parent['uri-id'], [Tag::MENTION, Tag::IMPLICIT_MENTION, Tag::EXCLUSIVE_MENTION]);
1075
1076                 $parent_author = Contact::getByURL($parent['author-link'], false, ['url', 'nurl', 'alias']);
1077
1078                 $implicit_mentions = [];
1079                 if (empty($parent_author['url'])) {
1080                         Logger::notice('Author public contact unknown.', ['author-link' => $parent['author-link'], 'item-id' => $parent['id']]);
1081                 } else {
1082                         $implicit_mentions[] = $parent_author['url'];
1083                         $implicit_mentions[] = $parent_author['nurl'];
1084                         $implicit_mentions[] = $parent_author['alias'];
1085                 }
1086
1087                 if (!empty($parent['alias'])) {
1088                         $implicit_mentions[] = $parent['alias'];
1089                 }
1090
1091                 foreach ($parent_terms as $term) {
1092                         $contact = Contact::getByURL($term['url'], false, ['url', 'nurl', 'alias']);
1093                         if (!empty($contact['url'])) {
1094                                 $implicit_mentions[] = $contact['url'];
1095                                 $implicit_mentions[] = $contact['nurl'];
1096                                 $implicit_mentions[] = $contact['alias'];
1097                         }
1098                 }
1099
1100                 return $implicit_mentions;
1101         }
1102
1103         /**
1104          * Strips from the body prepended implicit mentions
1105          *
1106          * @param string $body
1107          * @param array $parent
1108          * @return string
1109          */
1110         private static function removeImplicitMentionsFromBody(string $body, array $parent)
1111         {
1112                 if (DI::config()->get('system', 'disable_implicit_mentions')) {
1113                         return $body;
1114                 }
1115
1116                 $potential_mentions = self::getImplicitMentionList($parent);
1117
1118                 $kept_mentions = [];
1119
1120                 // Extract one prepended mention at a time from the body
1121                 while(preg_match('#^(@\[url=([^\]]+)].*?\[\/url]\s)(.*)#is', $body, $matches)) {
1122                         if (!in_array($matches[2], $potential_mentions)) {
1123                                 $kept_mentions[] = $matches[1];
1124                         }
1125
1126                         $body = $matches[3];
1127                 }
1128
1129                 // Re-appending the kept mentions to the body after extraction
1130                 $kept_mentions[] = $body;
1131
1132                 return implode('', $kept_mentions);
1133         }
1134 }