]> git.mxchange.org Git - friendica.git/blob - src/Protocol/ActivityPub/Receiver.php
Merge pull request #8345 from annando/store-raw
[friendica.git] / src / Protocol / ActivityPub / Receiver.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\Database\DBA;
25 use Friendica\Content\Text\HTML;
26 use Friendica\Content\Text\Markdown;
27 use Friendica\Core\Logger;
28 use Friendica\Core\Protocol;
29 use Friendica\Model\Contact;
30 use Friendica\Model\APContact;
31 use Friendica\Model\Item;
32 use Friendica\Model\User;
33 use Friendica\Protocol\Activity;
34 use Friendica\Protocol\ActivityPub;
35 use Friendica\Util\DateTimeFormat;
36 use Friendica\Util\HTTPSignature;
37 use Friendica\Util\JsonLD;
38 use Friendica\Util\LDSignature;
39 use Friendica\Util\Strings;
40
41 /**
42  * ActivityPub Receiver Protocol class
43  *
44  * To-Do:
45  * @todo Undo Announce
46  *
47  * Check what this is meant to do:
48  * - Add
49  * - Block
50  * - Flag
51  * - Remove
52  * - Undo Block
53  */
54 class Receiver
55 {
56         const PUBLIC_COLLECTION = 'as:Public';
57         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
58         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event'];
59         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
60
61         /**
62          * Checks if the web request is done for the AP protocol
63          *
64          * @return bool is it AP?
65          */
66         public static function isRequest()
67         {
68                 return stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/activity+json') ||
69                         stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/ld+json');
70         }
71
72         /**
73          * Checks incoming message from the inbox
74          *
75          * @param         $body
76          * @param         $header
77          * @param integer $uid User ID
78          * @throws \Exception
79          */
80         public static function processInbox($body, $header, $uid)
81         {
82                 $http_signer = HTTPSignature::getSigner($body, $header);
83                 if (empty($http_signer)) {
84                         Logger::warning('Invalid HTTP signature, message will be discarded.');
85                         return;
86                 } else {
87                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
88                 }
89
90                 $activity = json_decode($body, true);
91
92                 if (empty($activity)) {
93                         Logger::warning('Invalid body.');
94                         return;
95                 }
96
97                 $ldactivity = JsonLD::compact($activity);
98
99                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor', '@id');
100
101                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
102
103                 if (LDSignature::isSigned($activity)) {
104                         $ld_signer = LDSignature::getSigner($activity);
105                         if (empty($ld_signer)) {
106                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
107                         }
108                         if (!empty($ld_signer && ($actor == $http_signer))) {
109                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
110                                 $trust_source = true;
111                         } elseif (!empty($ld_signer)) {
112                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
113                                 $trust_source = true;
114                         } elseif ($actor == $http_signer) {
115                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
116                                 $trust_source = true;
117                         } else {
118                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
119                                 $trust_source = false;
120                         }
121                 } elseif ($actor == $http_signer) {
122                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
123                         $trust_source = true;
124                 } else {
125                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
126                         $trust_source = false;
127                 }
128
129                 self::processActivity($ldactivity, $body, $uid, $trust_source);
130         }
131
132         /**
133          * Fetches the object type for a given object id
134          *
135          * @param array   $activity
136          * @param string  $object_id Object ID of the the provided object
137          * @param integer $uid       User ID
138          *
139          * @return string with object type
140          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
141          * @throws \ImagickException
142          */
143         private static function fetchObjectType($activity, $object_id, $uid = 0)
144         {
145                 if (!empty($activity['as:object'])) {
146                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
147                         if (!empty($object_type)) {
148                                 return $object_type;
149                         }
150                 }
151
152                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
153                         // We just assume "note" since it doesn't make a difference for the further processing
154                         return 'as:Note';
155                 }
156
157                 $profile = APContact::getByURL($object_id);
158                 if (!empty($profile['type'])) {
159                         return 'as:' . $profile['type'];
160                 }
161
162                 $data = ActivityPub::fetchContent($object_id, $uid);
163                 if (!empty($data)) {
164                         $object = JsonLD::compact($data);
165                         $type = JsonLD::fetchElement($object, '@type');
166                         if (!empty($type)) {
167                                 return $type;
168                         }
169                 }
170
171                 return null;
172         }
173
174         /**
175          * Prepare the object array
176          *
177          * @param array   $activity
178          * @param integer $uid User ID
179          * @param         $trust_source
180          *
181          * @return array with object data
182          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
183          * @throws \ImagickException
184          */
185         private static function prepareObjectData($activity, $uid, &$trust_source)
186         {
187                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
188                 if (empty($actor)) {
189                         Logger::log('Empty actor', Logger::DEBUG);
190                         return [];
191                 }
192
193                 $type = JsonLD::fetchElement($activity, '@type');
194
195                 // Fetch all receivers from to, cc, bto and bcc
196                 $receivers = self::getReceivers($activity, $actor);
197
198                 // When it is a delivery to a personal inbox we add that user to the receivers
199                 if (!empty($uid)) {
200                         $additional = ['uid:' . $uid => $uid];
201                         $receivers = array_merge($receivers, $additional);
202                 } else {
203                         // We possibly need some user to fetch private content,
204                         // so we fetch the first out ot the list.
205                         $uid = self::getFirstUserFromReceivers($receivers);
206                 }
207
208                 Logger::log('Receivers: ' . $uid . ' - ' . json_encode($receivers), Logger::DEBUG);
209
210                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
211                 if (empty($object_id)) {
212                         Logger::log('No object found', Logger::DEBUG);
213                         return [];
214                 }
215
216                 if (!is_string($object_id)) {
217                         Logger::info('Invalid object id', ['object' => $object_id]);
218                         return [];
219                 }
220
221                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
222
223                 // Fetch the content only on activities where this matters
224                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
225                         if ($type == 'as:Announce') {
226                                 $trust_source = false;
227                         }
228                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $uid);
229                         if (empty($object_data)) {
230                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
231                                 return [];
232                         }
233                         $object_data['object_id'] = $object_id;
234
235                         // Test if it is an answer to a mail
236                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
237                                 $object_data['directmessage'] = true;
238                         } else {
239                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
240                         }
241
242                         // We had been able to retrieve the object data - so we can trust the source
243                         $trust_source = true;
244                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
245                         // Create a mostly empty array out of the activity data (instead of the object).
246                         // This way we later don't have to check for the existence of ech individual array element.
247                         $object_data = self::processObject($activity);
248                         $object_data['name'] = $type;
249                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
250                         $object_data['object_id'] = $object_id;
251                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
252                 } elseif (in_array($type, ['as:Add'])) {
253                         $object_data = [];
254                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
255                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
256                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
257                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
258                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
259                 } else {
260                         $object_data = [];
261                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
262                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
263                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
264                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
265                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
266
267                         // An Undo is done on the object of an object, so we need that type as well
268                         if ($type == 'as:Undo') {
269                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
270                         }
271                 }
272
273                 $object_data = self::addActivityFields($object_data, $activity);
274
275                 if (empty($object_data['object_type'])) {
276                         $object_data['object_type'] = $object_type;
277                 }
278
279                 $object_data['type'] = $type;
280                 $object_data['actor'] = $actor;
281                 $object_data['item_receiver'] = $receivers;
282                 $object_data['receiver'] = array_merge($object_data['receiver'] ?? [], $receivers);
283
284                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
285
286                 return $object_data;
287         }
288
289         /**
290          * Fetches the first user id from the receiver array
291          *
292          * @param array $receivers Array with receivers
293          * @return integer user id;
294          */
295         public static function getFirstUserFromReceivers($receivers)
296         {
297                 foreach ($receivers as $receiver) {
298                         if (!empty($receiver)) {
299                                 return $receiver;
300                         }
301                 }
302                 return 0;
303         }
304
305         /**
306          * Processes the activity object
307          *
308          * @param array   $activity     Array with activity data
309          * @param string  $body
310          * @param integer $uid          User ID
311          * @param boolean $trust_source Do we trust the source?
312          * @throws \Exception
313          */
314         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false)
315         {
316                 $type = JsonLD::fetchElement($activity, '@type');
317                 if (!$type) {
318                         Logger::log('Empty type', Logger::DEBUG);
319                         return;
320                 }
321
322                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
323                         Logger::log('Empty object', Logger::DEBUG);
324                         return;
325                 }
326
327                 if (!JsonLD::fetchElement($activity, 'as:actor', '@id')) {
328                         Logger::log('Empty actor', Logger::DEBUG);
329                         return;
330
331                 }
332
333                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
334                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
335                         $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
336                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
337                         $trust_source = ($actor == $attributed_to);
338                         if (!$trust_source) {
339                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
340                         }
341                 }
342
343                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
344                 $object_data = self::prepareObjectData($activity, $uid, $trust_source);
345                 if (empty($object_data)) {
346                         Logger::log('No object data found', Logger::DEBUG);
347                         return;
348                 }
349
350                 if (!$trust_source) {
351                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
352                         return;
353                 }
354
355                 if (!empty($body)) {
356                         $object_data['raw'] = $body;
357                 }
358
359                 // Internal flag for thread completion. See Processor.php
360                 if (!empty($activity['thread-completion'])) {
361                         $object_data['thread-completion'] = $activity['thread-completion'];
362                 }
363
364                 switch ($type) {
365                         case 'as:Create':
366                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
367                                         ActivityPub\Processor::createItem($object_data);
368                                 }
369                                 break;
370
371                         case 'as:Add':
372                                 if ($object_data['object_type'] == 'as:tag') {
373                                         ActivityPub\Processor::addTag($object_data);
374                                 }
375                                 break;
376
377                         case 'as:Announce':
378                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
379                                         $profile = APContact::getByURL($object_data['actor']);
380                                         // Reshared posts from persons appear as summary at the bottom
381                                         // If this isn't set, then a single reshare appears on top. This is used for groups.
382                                         $object_data['thread-completion'] = ($profile['type'] != 'Group');
383
384                                         ActivityPub\Processor::createItem($object_data);
385
386                                         // Add the bottom reshare information only for persons
387                                         if ($profile['type'] != 'Group') {
388                                                 $announce_object_data = self::processObject($activity);
389                                                 $announce_object_data['name'] = $type;
390                                                 $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
391                                                 $announce_object_data['object_id'] = $object_data['object_id'];
392                                                 $announce_object_data['object_type'] = $object_data['object_type'];
393
394                                                 ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
395                                         }
396                                 }
397                                 break;
398
399                         case 'as:Like':
400                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
401                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
402                                 }
403                                 break;
404
405                         case 'as:Dislike':
406                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
407                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
408                                 }
409                                 break;
410
411                         case 'as:TentativeAccept':
412                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
413                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
414                                 }
415                                 break;
416
417                         case 'as:Update':
418                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
419                                         ActivityPub\Processor::updateItem($object_data);
420                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
421                                         ActivityPub\Processor::updatePerson($object_data);
422                                 }
423                                 break;
424
425                         case 'as:Delete':
426                                 if ($object_data['object_type'] == 'as:Tombstone') {
427                                         ActivityPub\Processor::deleteItem($object_data);
428                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
429                                         ActivityPub\Processor::deletePerson($object_data);
430                                 }
431                                 break;
432
433                         case 'as:Follow':
434                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
435                                         ActivityPub\Processor::followUser($object_data);
436                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
437                                         $object_data['reply-to-id'] = $object_data['object_id'];
438                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
439                                 }
440                                 break;
441
442                         case 'as:Accept':
443                                 if ($object_data['object_type'] == 'as:Follow') {
444                                         ActivityPub\Processor::acceptFollowUser($object_data);
445                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
446                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
447                                 }
448                                 break;
449
450                         case 'as:Reject':
451                                 if ($object_data['object_type'] == 'as:Follow') {
452                                         ActivityPub\Processor::rejectFollowUser($object_data);
453                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
454                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
455                                 }
456                                 break;
457
458                         case 'as:Undo':
459                                 if (($object_data['object_type'] == 'as:Follow') &&
460                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
461                                         ActivityPub\Processor::undoFollowUser($object_data);
462                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
463                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
464                                         ActivityPub\Processor::rejectFollowUser($object_data);
465                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
466                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
467                                         ActivityPub\Processor::undoActivity($object_data);
468                                 }
469                                 break;
470
471                         default:
472                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
473                                 break;
474                 }
475         }
476
477         /**
478          * Fetch the receiver list from an activity array
479          *
480          * @param array  $activity
481          * @param string $actor
482          * @param array  $tags
483          *
484          * @return array with receivers (user id)
485          * @throws \Exception
486          */
487         private static function getReceivers($activity, $actor, $tags = [])
488         {
489                 $receivers = [];
490
491                 // When it is an answer, we inherite the receivers from the parent
492                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
493                 if (!empty($replyto)) {
494                         // Fix possibly wrong item URI (could be an answer to a plink uri)
495                         $fixedReplyTo = Item::getURIByLink($replyto);
496                         $replyto = $fixedReplyTo ?: $replyto;
497
498                         $parents = Item::select(['uid'], ['uri' => $replyto]);
499                         while ($parent = Item::fetch($parents)) {
500                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
501                         }
502                 }
503
504                 if (!empty($actor)) {
505                         $profile = APContact::getByURL($actor);
506                         $followers = $profile['followers'] ?? '';
507
508                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
509                 } else {
510                         Logger::log('Empty actor', Logger::DEBUG);
511                         $followers = '';
512                 }
513
514                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
515                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
516                         if (empty($receiver_list)) {
517                                 continue;
518                         }
519
520                         foreach ($receiver_list as $receiver) {
521                                 if ($receiver == self::PUBLIC_COLLECTION) {
522                                         $receivers['uid:0'] = 0;
523                                 }
524
525                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
526                                         // This will most likely catch all OStatus connections to Mastodon
527                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
528                                                 , 'archive' => false, 'pending' => false];
529                                         $contacts = DBA::select('contact', ['uid'], $condition);
530                                         while ($contact = DBA::fetch($contacts)) {
531                                                 if ($contact['uid'] != 0) {
532                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
533                                                 }
534                                         }
535                                         DBA::close($contacts);
536                                 }
537
538                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
539                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
540                                         continue;
541                                 }
542
543                                 // Fetching all directly addressed receivers
544                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
545                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
546                                 if (!DBA::isResult($contact)) {
547                                         continue;
548                                 }
549
550                                 // Check if the potential receiver is following the actor
551                                 // Exception: The receiver is targetted via "to" or this is a comment
552                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
553                                         $networks = Protocol::FEDERATED;
554                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
555                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
556
557                                         // Forum posts are only accepted from forum contacts
558                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
559                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
560                                         }
561
562                                         if (!DBA::exists('contact', $condition)) {
563                                                 continue;
564                                         }
565                                 }
566
567                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
568                         }
569                 }
570
571                 self::switchContacts($receivers, $actor);
572
573                 return $receivers;
574         }
575
576         /**
577          * Fetch the receiver list of a given actor
578          *
579          * @param string $actor
580          * @param array  $tags
581          *
582          * @return array with receivers (user id)
583          * @throws \Exception
584          */
585         public static function getReceiverForActor($actor, $tags)
586         {
587                 $receivers = [];
588                 $networks = Protocol::FEDERATED;
589                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
590                         'network' => $networks, 'archive' => false, 'pending' => false];
591                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
592                 while ($contact = DBA::fetch($contacts)) {
593                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
594                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
595                         }
596                 }
597                 DBA::close($contacts);
598                 return $receivers;
599         }
600
601         /**
602          * Tests if the contact is a valid receiver for this actor
603          *
604          * @param array  $contact
605          * @param string $actor
606          * @param array  $tags
607          *
608          * @return bool with receivers (user id)
609          * @throws \Exception
610          */
611         private static function isValidReceiverForActor($contact, $actor, $tags)
612         {
613                 // Public contacts are no valid receiver
614                 if ($contact['uid'] == 0) {
615                         return false;
616                 }
617
618                 // Are we following the contact? Then this is a valid receiver
619                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
620                         return true;
621                 }
622
623                 // When the possible receiver isn't a community, then it is no valid receiver
624                 $owner = User::getOwnerDataById($contact['uid']);
625                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
626                         return false;
627                 }
628
629                 // Is the community account tagged?
630                 foreach ($tags as $tag) {
631                         if ($tag['type'] != 'Mention') {
632                                 continue;
633                         }
634
635                         if ($tag['href'] == $owner['url']) {
636                                 return true;
637                         }
638                 }
639
640                 return false;
641         }
642
643         /**
644          * Switches existing contacts to ActivityPub
645          *
646          * @param integer $cid Contact ID
647          * @param integer $uid User ID
648          * @param string  $url Profile URL
649          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
650          * @throws \ImagickException
651          */
652         public static function switchContact($cid, $uid, $url)
653         {
654                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
655                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
656                         return;
657                 }
658
659                 if (Contact::updateFromProbe($cid, '', true)) {
660                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
661                 }
662
663                 // Send a new follow request to be sure that the connection still exists
664                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
665                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
666                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
667                 }
668         }
669
670         /**
671          *
672          *
673          * @param $receivers
674          * @param $actor
675          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
676          * @throws \ImagickException
677          */
678         private static function switchContacts($receivers, $actor)
679         {
680                 if (empty($actor)) {
681                         return;
682                 }
683
684                 foreach ($receivers as $receiver) {
685                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
686                         if (DBA::isResult($contact)) {
687                                 self::switchContact($contact['id'], $receiver, $actor);
688                         }
689
690                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
691                         if (DBA::isResult($contact)) {
692                                 self::switchContact($contact['id'], $receiver, $actor);
693                         }
694                 }
695         }
696
697         /**
698          *
699          *
700          * @param       $object_data
701          * @param array $activity
702          *
703          * @return mixed
704          */
705         private static function addActivityFields($object_data, $activity)
706         {
707                 if (!empty($activity['published']) && empty($object_data['published'])) {
708                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
709                 }
710
711                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
712                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
713                 }
714
715                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
716                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
717
718                 if (!empty($object_data['object_id'])) {
719                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
720                         $objectId = Item::getURIByLink($object_data['object_id']);
721                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
722                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
723                                 $object_data['object_id'] = $objectId;
724                         }
725                 }
726
727                 return $object_data;
728         }
729
730         /**
731          * Fetches the object data from external ressources if needed
732          *
733          * @param string  $object_id    Object ID of the the provided object
734          * @param array   $object       The provided object array
735          * @param boolean $trust_source Do we trust the provided object?
736          * @param integer $uid          User ID for the signature that we use to fetch data
737          *
738          * @return array|false with trusted and valid object data
739          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
740          * @throws \ImagickException
741          */
742         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
743         {
744                 // By fetching the type we check if the object is complete.
745                 $type = JsonLD::fetchElement($object, '@type');
746
747                 if (!$trust_source || empty($type)) {
748                         $data = ActivityPub::fetchContent($object_id, $uid);
749                         if (!empty($data)) {
750                                 $object = JsonLD::compact($data);
751                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
752                         } else {
753                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
754
755                                 $item = Item::selectFirst([], ['uri' => $object_id]);
756                                 if (!DBA::isResult($item)) {
757                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
758                                         return false;
759                                 }
760                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
761                                 $data = ActivityPub\Transmitter::createNote($item);
762                                 $object = JsonLD::compact($data);
763                         }
764                 } else {
765                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
766                 }
767
768                 $type = JsonLD::fetchElement($object, '@type');
769
770                 if (empty($type)) {
771                         Logger::log('Empty type', Logger::DEBUG);
772                         return false;
773                 }
774
775                 if (in_array($type, self::CONTENT_TYPES)) {
776                         return self::processObject($object);
777                 }
778
779                 if ($type == 'as:Announce') {
780                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
781                         if (empty($object_id) || !is_string($object_id)) {
782                                 return false;
783                         }
784                         return self::fetchObject($object_id, [], false, $uid);
785                 }
786
787                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
788                 return false;
789         }
790
791         /**
792          * Convert tags from JSON-LD format into a simplified format
793          *
794          * @param array $tags Tags in JSON-LD format
795          *
796          * @return array with tags in a simplified format
797          */
798         private static function processTags($tags)
799         {
800                 $taglist = [];
801
802                 if (empty($tags)) {
803                         return [];
804                 }
805
806                 foreach ($tags as $tag) {
807                         if (empty($tag)) {
808                                 continue;
809                         }
810
811                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
812                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
813                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
814
815                         if (empty($element['type'])) {
816                                 continue;
817                         }
818
819                         $taglist[] = $element;
820                 }
821                 return $taglist;
822         }
823
824         /**
825          * Convert emojis from JSON-LD format into a simplified format
826          *
827          * @param $emojis
828          * @return array with emojis in a simplified format
829          */
830         private static function processEmojis($emojis)
831         {
832                 $emojilist = [];
833
834                 if (empty($emojis)) {
835                         return [];
836                 }
837
838                 foreach ($emojis as $emoji) {
839                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
840                                 continue;
841                         }
842
843                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
844                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
845                                 'href' => $url];
846
847                         $emojilist[] = $element;
848                 }
849                 return $emojilist;
850         }
851
852         /**
853          * Convert attachments from JSON-LD format into a simplified format
854          *
855          * @param array $attachments Attachments in JSON-LD format
856          *
857          * @return array with attachmants in a simplified format
858          */
859         private static function processAttachments($attachments)
860         {
861                 $attachlist = [];
862
863                 if (empty($attachments)) {
864                         return [];
865                 }
866
867                 foreach ($attachments as $attachment) {
868                         if (empty($attachment)) {
869                                 continue;
870                         }
871
872                         $attachlist[] = ['type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
873                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
874                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
875                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')];
876                 }
877                 return $attachlist;
878         }
879
880         /**
881          * Fetch the original source or content with the "language" Markdown or HTML
882          *
883          * @param array $object
884          * @param array $object_data
885          *
886          * @return array
887          * @throws \Exception
888          */
889         private static function getSource($object, $object_data)
890         {
891                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
892                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
893                 if (!empty($object_data['source'])) {
894                         return $object_data;
895                 }
896
897                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
898                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
899                 if (!empty($object_data['source'])) {
900                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
901                         return $object_data;
902                 }
903
904                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
905                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
906                 if (!empty($object_data['source'])) {
907                         $object_data['source'] = HTML::toBBCode($object_data['source']);
908                         return $object_data;
909                 }
910
911                 return $object_data;
912         }
913
914         /**
915          * Fetches data from the object part of an activity
916          *
917          * @param array $object
918          *
919          * @return array
920          * @throws \Exception
921          */
922         private static function processObject($object)
923         {
924                 if (!JsonLD::fetchElement($object, '@id')) {
925                         return false;
926                 }
927
928                 $object_data = [];
929                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
930                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
931                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
932
933                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
934                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
935                         $object_data['reply-to-id'] = $object_data['id'];
936                 } else {
937                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
938                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
939                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
940                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
941                                 $object_data['reply-to-id'] = $replyToId;
942                         }
943                 }
944
945                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
946                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
947
948                 if (empty($object_data['updated'])) {
949                         $object_data['updated'] = $object_data['published'];
950                 }
951
952                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
953                         $object_data['published'] = $object_data['updated'];
954                 }
955
956                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
957                 if (empty($actor)) {
958                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
959                 }
960
961                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
962                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
963                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
964                 $object_data['actor'] = $object_data['author'] = $actor;
965                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
966                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
967                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
968                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
969                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
970                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
971                 $object_data = self::getSource($object, $object_data);
972                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
973                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
974                 $object_data['location'] = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
975                 $object_data['location'] = JsonLD::fetchElement($object_data, 'location', '@value');
976                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
977                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
978                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
979                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
980                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment'));
981                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag'));
982                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji'));
983                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
984                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
985                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
986
987                 // Special treatment for Hubzilla links
988                 if (is_array($object_data['alternate-url'])) {
989                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
990
991                         if (!is_string($object_data['alternate-url'])) {
992                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
993                         }
994                 }
995
996                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags']);
997
998                 // Common object data:
999
1000                 // Unhandled
1001                 // @context, type, actor, signature, mediaType, duration, replies, icon
1002
1003                 // Also missing: (Defined in the standard, but currently unused)
1004                 // audience, preview, endTime, startTime, image
1005
1006                 // Data in Notes:
1007
1008                 // Unhandled
1009                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1010                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1011
1012                 // Data in video:
1013
1014                 // To-Do?
1015                 // category, licence, language, commentsEnabled
1016
1017                 // Unhandled
1018                 // views, waitTranscoding, state, support, subtitleLanguage
1019                 // likes, dislikes, shares, comments
1020
1021                 return $object_data;
1022         }
1023 }