]> git.mxchange.org Git - friendica.git/blob - src/Protocol/ActivityPub/Receiver.php
Separate concerns between postItem and createItem in ActivityPub\Processor
[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\Content\Text\BBCode;
25 use Friendica\Database\DBA;
26 use Friendica\Content\Text\HTML;
27 use Friendica\Content\Text\Markdown;
28 use Friendica\Core\Logger;
29 use Friendica\Core\Protocol;
30 use Friendica\Model\Contact;
31 use Friendica\Model\APContact;
32 use Friendica\Model\Item;
33 use Friendica\Model\User;
34 use Friendica\Protocol\Activity;
35 use Friendica\Protocol\ActivityPub;
36 use Friendica\Util\DateTimeFormat;
37 use Friendica\Util\HTTPSignature;
38 use Friendica\Util\JsonLD;
39 use Friendica\Util\LDSignature;
40 use Friendica\Util\Strings;
41
42 /**
43  * ActivityPub Receiver Protocol class
44  *
45  * To-Do:
46  * @todo Undo Announce
47  *
48  * Check what this is meant to do:
49  * - Add
50  * - Block
51  * - Flag
52  * - Remove
53  * - Undo Block
54  */
55 class Receiver
56 {
57         const PUBLIC_COLLECTION = 'as:Public';
58         const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
59         const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event', 'as:Audio'];
60         const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
61
62         /**
63          * Checks if the web request is done for the AP protocol
64          *
65          * @return bool is it AP?
66          */
67         public static function isRequest()
68         {
69                 return stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/activity+json') ||
70                         stristr($_SERVER['HTTP_ACCEPT'] ?? '', 'application/ld+json');
71         }
72
73         /**
74          * Checks incoming message from the inbox
75          *
76          * @param         $body
77          * @param         $header
78          * @param integer $uid User ID
79          * @throws \Exception
80          */
81         public static function processInbox($body, $header, $uid)
82         {
83                 $http_signer = HTTPSignature::getSigner($body, $header);
84                 if (empty($http_signer)) {
85                         Logger::warning('Invalid HTTP signature, message will be discarded.');
86                         return;
87                 } else {
88                         Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
89                 }
90
91                 $activity = json_decode($body, true);
92
93                 if (empty($activity)) {
94                         Logger::warning('Invalid body.');
95                         return;
96                 }
97
98                 $ldactivity = JsonLD::compact($activity);
99
100                 $actor = JsonLD::fetchElement($ldactivity, 'as:actor', '@id');
101
102                 Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
103
104                 if (LDSignature::isSigned($activity)) {
105                         $ld_signer = LDSignature::getSigner($activity);
106                         if (empty($ld_signer)) {
107                                 Logger::log('Invalid JSON-LD signature from ' . $actor, Logger::DEBUG);
108                         }
109                         if (!empty($ld_signer && ($actor == $http_signer))) {
110                                 Logger::log('The HTTP and the JSON-LD signature belong to ' . $ld_signer, Logger::DEBUG);
111                                 $trust_source = true;
112                         } elseif (!empty($ld_signer)) {
113                                 Logger::log('JSON-LD signature is signed by ' . $ld_signer, Logger::DEBUG);
114                                 $trust_source = true;
115                         } elseif ($actor == $http_signer) {
116                                 Logger::log('Bad JSON-LD signature, but HTTP signer fits the actor.', Logger::DEBUG);
117                                 $trust_source = true;
118                         } else {
119                                 Logger::log('Invalid JSON-LD signature and the HTTP signer is different.', Logger::DEBUG);
120                                 $trust_source = false;
121                         }
122                 } elseif ($actor == $http_signer) {
123                         Logger::log('Trusting post without JSON-LD signature, The actor fits the HTTP signer.', Logger::DEBUG);
124                         $trust_source = true;
125                 } else {
126                         Logger::log('No JSON-LD signature, different actor.', Logger::DEBUG);
127                         $trust_source = false;
128                 }
129
130                 self::processActivity($ldactivity, $body, $uid, $trust_source, true);
131         }
132
133         /**
134          * Fetches the object type for a given object id
135          *
136          * @param array   $activity
137          * @param string  $object_id Object ID of the the provided object
138          * @param integer $uid       User ID
139          *
140          * @return string with object type
141          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
142          * @throws \ImagickException
143          */
144         private static function fetchObjectType($activity, $object_id, $uid = 0)
145         {
146                 if (!empty($activity['as:object'])) {
147                         $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
148                         if (!empty($object_type)) {
149                                 return $object_type;
150                         }
151                 }
152
153                 if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
154                         // We just assume "note" since it doesn't make a difference for the further processing
155                         return 'as:Note';
156                 }
157
158                 $profile = APContact::getByURL($object_id);
159                 if (!empty($profile['type'])) {
160                         return 'as:' . $profile['type'];
161                 }
162
163                 $data = ActivityPub::fetchContent($object_id, $uid);
164                 if (!empty($data)) {
165                         $object = JsonLD::compact($data);
166                         $type = JsonLD::fetchElement($object, '@type');
167                         if (!empty($type)) {
168                                 return $type;
169                         }
170                 }
171
172                 return null;
173         }
174
175         /**
176          * Prepare the object array
177          *
178          * @param array   $activity     Array with activity data
179          * @param integer $uid          User ID
180          * @param boolean $push         Message had been pushed to our system
181          * @param boolean $trust_source Do we trust the source?
182          *
183          * @return array with object data
184          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
185          * @throws \ImagickException
186          */
187         private static function prepareObjectData($activity, $uid, $push, &$trust_source)
188         {
189                 $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
190                 if (empty($actor)) {
191                         Logger::log('Empty actor', Logger::DEBUG);
192                         return [];
193                 }
194
195                 $type = JsonLD::fetchElement($activity, '@type');
196
197                 // Fetch all receivers from to, cc, bto and bcc
198                 $receivers = self::getReceivers($activity, $actor);
199
200                 // When it is a delivery to a personal inbox we add that user to the receivers
201                 if (!empty($uid)) {
202                         $additional = ['uid:' . $uid => $uid];
203                         $receivers = array_merge($receivers, $additional);
204                 } else {
205                         // We possibly need some user to fetch private content,
206                         // so we fetch the first out ot the list.
207                         $uid = self::getFirstUserFromReceivers($receivers);
208                 }
209
210                 Logger::log('Receivers: ' . $uid . ' - ' . json_encode($receivers), Logger::DEBUG);
211
212                 $object_id = JsonLD::fetchElement($activity, 'as:object', '@id');
213                 if (empty($object_id)) {
214                         Logger::log('No object found', Logger::DEBUG);
215                         return [];
216                 }
217
218                 if (!is_string($object_id)) {
219                         Logger::info('Invalid object id', ['object' => $object_id]);
220                         return [];
221                 }
222
223                 $object_type = self::fetchObjectType($activity, $object_id, $uid);
224
225                 // Fetch the content only on activities where this matters
226                 if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
227                         if ($type == 'as:Announce') {
228                                 $trust_source = false;
229                         }
230
231                         $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $uid);
232                         if (empty($object_data)) {
233                                 Logger::log("Object data couldn't be processed", Logger::DEBUG);
234                                 return [];
235                         }
236
237                         $object_data['object_id'] = $object_id;
238
239                         if ($type == 'as:Announce') {
240                                 $object_data['push'] = false;
241                         } else {
242                                 $object_data['push'] = $push;
243                         }
244
245                         // Test if it is an answer to a mail
246                         if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
247                                 $object_data['directmessage'] = true;
248                         } else {
249                                 $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
250                         }
251
252                         // We had been able to retrieve the object data - so we can trust the source
253                         $trust_source = true;
254                 } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
255                         // Create a mostly empty array out of the activity data (instead of the object).
256                         // This way we later don't have to check for the existence of ech individual array element.
257                         $object_data = self::processObject($activity);
258                         $object_data['name'] = $type;
259                         $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
260                         $object_data['object_id'] = $object_id;
261                         $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
262                 } elseif (in_array($type, ['as:Add'])) {
263                         $object_data = [];
264                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
265                         $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
266                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
267                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
268                         $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
269                 } else {
270                         $object_data = [];
271                         $object_data['id'] = JsonLD::fetchElement($activity, '@id');
272                         $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
273                         $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
274                         $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
275                         $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
276
277                         // An Undo is done on the object of an object, so we need that type as well
278                         if (($type == 'as:Undo') && !empty($object_data['object_object'])) {
279                                 $object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object'], $uid);
280                         }
281                 }
282
283                 $object_data = self::addActivityFields($object_data, $activity);
284
285                 if (empty($object_data['object_type'])) {
286                         $object_data['object_type'] = $object_type;
287                 }
288
289                 $object_data['type'] = $type;
290                 $object_data['actor'] = $actor;
291                 $object_data['item_receiver'] = $receivers;
292                 $object_data['receiver'] = array_merge($object_data['receiver'] ?? [], $receivers);
293
294                 Logger::log('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id'], Logger::DEBUG);
295
296                 return $object_data;
297         }
298
299         /**
300          * Fetches the first user id from the receiver array
301          *
302          * @param array $receivers Array with receivers
303          * @return integer user id;
304          */
305         public static function getFirstUserFromReceivers($receivers)
306         {
307                 foreach ($receivers as $receiver) {
308                         if (!empty($receiver)) {
309                                 return $receiver;
310                         }
311                 }
312                 return 0;
313         }
314
315         /**
316          * Processes the activity object
317          *
318          * @param array   $activity     Array with activity data
319          * @param string  $body
320          * @param integer $uid          User ID
321          * @param boolean $trust_source Do we trust the source?
322          * @param boolean $push         Message had been pushed to our system
323          * @throws \Exception
324          */
325         public static function processActivity($activity, $body = '', $uid = null, $trust_source = false, $push = false)
326         {
327                 $type = JsonLD::fetchElement($activity, '@type');
328                 if (!$type) {
329                         Logger::log('Empty type', Logger::DEBUG);
330                         return;
331                 }
332
333                 if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
334                         Logger::log('Empty object', Logger::DEBUG);
335                         return;
336                 }
337
338                 if (!JsonLD::fetchElement($activity, 'as:actor', '@id')) {
339                         Logger::log('Empty actor', Logger::DEBUG);
340                         return;
341                 }
342
343                 // Don't trust the source if "actor" differs from "attributedTo". The content could be forged.
344                 if ($trust_source && ($type == 'as:Create') && is_array($activity['as:object'])) {
345                         $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
346                         $attributed_to = JsonLD::fetchElement($activity['as:object'], 'as:attributedTo', '@id');
347                         $trust_source = ($actor == $attributed_to);
348                         if (!$trust_source) {
349                                 Logger::log('Not trusting actor: ' . $actor . '. It differs from attributedTo: ' . $attributed_to, Logger::DEBUG);
350                         }
351                 }
352
353                 // $trust_source is called by reference and is set to true if the content was retrieved successfully
354                 $object_data = self::prepareObjectData($activity, $uid, $push, $trust_source);
355                 if (empty($object_data)) {
356                         Logger::log('No object data found', Logger::DEBUG);
357                         return;
358                 }
359
360                 if (!$trust_source) {
361                         Logger::log('No trust for activity type "' . $type . '", so we quit now.', Logger::DEBUG);
362                         return;
363                 }
364
365                 if (!empty($body) && empty($object_data['raw'])) {
366                         $object_data['raw'] = $body;
367                 }
368
369                 // Internal flag for thread completion. See Processor.php
370                 if (!empty($activity['thread-completion'])) {
371                         $object_data['thread-completion'] = $activity['thread-completion'];
372                 }
373
374                 switch ($type) {
375                         case 'as:Create':
376                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
377                                         $item = ActivityPub\Processor::createItem($object_data);
378                                         ActivityPub\Processor::postItem($object_data, $item);
379                                 }
380                                 break;
381
382                         case 'as:Add':
383                                 if ($object_data['object_type'] == 'as:tag') {
384                                         ActivityPub\Processor::addTag($object_data);
385                                 }
386                                 break;
387
388                         case 'as:Announce':
389                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
390                                         $profile = APContact::getByURL($object_data['actor']);
391                                         // Reshared posts from persons appear as summary at the bottom
392                                         // If this isn't set, then a single reshare appears on top. This is used for groups.
393                                         $object_data['thread-completion'] = ($profile['type'] != 'Group');
394
395                                         $item = ActivityPub\Processor::createItem($object_data);
396                                         ActivityPub\Processor::postItem($object_data, $item);
397
398                                         // Add the bottom reshare information only for persons
399                                         if ($profile['type'] != 'Group') {
400                                                 $announce_object_data = self::processObject($activity);
401                                                 $announce_object_data['name'] = $type;
402                                                 $announce_object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
403                                                 $announce_object_data['object_id'] = $object_data['object_id'];
404                                                 $announce_object_data['object_type'] = $object_data['object_type'];
405                                                 $announce_object_data['push'] = $push;
406
407                                                 if (!empty($body)) {
408                                                         $announce_object_data['raw'] = $body;
409                                                 }
410
411                                                 ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
412                                         }
413                                 }
414                                 break;
415
416                         case 'as:Like':
417                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
418                                         ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
419                                 }
420                                 break;
421
422                         case 'as:Dislike':
423                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
424                                         ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
425                                 }
426                                 break;
427
428                         case 'as:TentativeAccept':
429                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
430                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDMAYBE);
431                                 }
432                                 break;
433
434                         case 'as:Update':
435                                 if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
436                                         ActivityPub\Processor::updateItem($object_data);
437                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
438                                         ActivityPub\Processor::updatePerson($object_data);
439                                 }
440                                 break;
441
442                         case 'as:Delete':
443                                 if ($object_data['object_type'] == 'as:Tombstone') {
444                                         ActivityPub\Processor::deleteItem($object_data);
445                                 } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
446                                         ActivityPub\Processor::deletePerson($object_data);
447                                 }
448                                 break;
449
450                         case 'as:Follow':
451                                 if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
452                                         ActivityPub\Processor::followUser($object_data);
453                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
454                                         $object_data['reply-to-id'] = $object_data['object_id'];
455                                         ActivityPub\Processor::createActivity($object_data, Activity::FOLLOW);
456                                 }
457                                 break;
458
459                         case 'as:Accept':
460                                 if ($object_data['object_type'] == 'as:Follow') {
461                                         ActivityPub\Processor::acceptFollowUser($object_data);
462                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
463                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
464                                 }
465                                 break;
466
467                         case 'as:Reject':
468                                 if ($object_data['object_type'] == 'as:Follow') {
469                                         ActivityPub\Processor::rejectFollowUser($object_data);
470                                 } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
471                                         ActivityPub\Processor::createActivity($object_data, Activity::ATTENDNO);
472                                 }
473                                 break;
474
475                         case 'as:Undo':
476                                 if (($object_data['object_type'] == 'as:Follow') &&
477                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
478                                         ActivityPub\Processor::undoFollowUser($object_data);
479                                 } elseif (($object_data['object_type'] == 'as:Accept') &&
480                                         in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
481                                         ActivityPub\Processor::rejectFollowUser($object_data);
482                                 } elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
483                                         in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
484                                         ActivityPub\Processor::undoActivity($object_data);
485                                 }
486                                 break;
487
488                         default:
489                                 Logger::log('Unknown activity: ' . $type . ' ' . $object_data['object_type'], Logger::DEBUG);
490                                 break;
491                 }
492         }
493
494         /**
495          * Fetch the receiver list from an activity array
496          *
497          * @param array   $activity
498          * @param string  $actor
499          * @param array   $tags
500          * @param boolean $fetch_unlisted 
501          *
502          * @return array with receivers (user id)
503          * @throws \Exception
504          */
505         private static function getReceivers($activity, $actor, $tags = [], $fetch_unlisted = false)
506         {
507                 $receivers = [];
508
509                 // When it is an answer, we inherite the receivers from the parent
510                 $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
511                 if (!empty($replyto)) {
512                         // Fix possibly wrong item URI (could be an answer to a plink uri)
513                         $fixedReplyTo = Item::getURIByLink($replyto);
514                         $replyto = $fixedReplyTo ?: $replyto;
515
516                         $parents = Item::select(['uid'], ['uri' => $replyto]);
517                         while ($parent = Item::fetch($parents)) {
518                                 $receivers['uid:' . $parent['uid']] = $parent['uid'];
519                         }
520                 }
521
522                 if (!empty($actor)) {
523                         $profile = APContact::getByURL($actor);
524                         $followers = $profile['followers'] ?? '';
525
526                         Logger::log('Actor: ' . $actor . ' - Followers: ' . $followers, Logger::DEBUG);
527                 } else {
528                         Logger::log('Empty actor', Logger::DEBUG);
529                         $followers = '';
530                 }
531
532                 foreach (['as:to', 'as:cc', 'as:bto', 'as:bcc'] as $element) {
533                         $receiver_list = JsonLD::fetchElementArray($activity, $element, '@id');
534                         if (empty($receiver_list)) {
535                                 continue;
536                         }
537
538                         foreach ($receiver_list as $receiver) {
539                                 if ($receiver == self::PUBLIC_COLLECTION) {
540                                         $receivers['uid:0'] = 0;
541                                 }
542
543                                 // Add receiver "-1" for unlisted posts 
544                                 if ($fetch_unlisted && ($receiver == self::PUBLIC_COLLECTION) && ($element == 'as:cc')) {
545                                         $receivers['uid:-1'] = -1;
546                                 }
547
548                                 if (($receiver == self::PUBLIC_COLLECTION) && !empty($actor)) {
549                                         // This will most likely catch all OStatus connections to Mastodon
550                                         $condition = ['alias' => [$actor, Strings::normaliseLink($actor)], 'rel' => [Contact::SHARING, Contact::FRIEND]
551                                                 , 'archive' => false, 'pending' => false];
552                                         $contacts = DBA::select('contact', ['uid'], $condition);
553                                         while ($contact = DBA::fetch($contacts)) {
554                                                 if ($contact['uid'] != 0) {
555                                                         $receivers['uid:' . $contact['uid']] = $contact['uid'];
556                                                 }
557                                         }
558                                         DBA::close($contacts);
559                                 }
560
561                                 if (in_array($receiver, [$followers, self::PUBLIC_COLLECTION]) && !empty($actor)) {
562                                         $receivers = array_merge($receivers, self::getReceiverForActor($actor, $tags));
563                                         continue;
564                                 }
565
566                                 // Fetching all directly addressed receivers
567                                 $condition = ['self' => true, 'nurl' => Strings::normaliseLink($receiver)];
568                                 $contact = DBA::selectFirst('contact', ['uid', 'contact-type'], $condition);
569                                 if (!DBA::isResult($contact)) {
570                                         continue;
571                                 }
572
573                                 // Check if the potential receiver is following the actor
574                                 // Exception: The receiver is targetted via "to" or this is a comment
575                                 if ((($element != 'as:to') && empty($replyto)) || ($contact['contact-type'] == Contact::TYPE_COMMUNITY)) {
576                                         $networks = Protocol::FEDERATED;
577                                         $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND],
578                                                 'network' => $networks, 'archive' => false, 'pending' => false, 'uid' => $contact['uid']];
579
580                                         // Forum posts are only accepted from forum contacts
581                                         if ($contact['contact-type'] == Contact::TYPE_COMMUNITY) {
582                                                 $condition['rel'] = [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER];
583                                         }
584
585                                         if (!DBA::exists('contact', $condition)) {
586                                                 continue;
587                                         }
588                                 }
589
590                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
591                         }
592                 }
593
594                 self::switchContacts($receivers, $actor);
595
596                 return $receivers;
597         }
598
599         /**
600          * Fetch the receiver list of a given actor
601          *
602          * @param string $actor
603          * @param array  $tags
604          *
605          * @return array with receivers (user id)
606          * @throws \Exception
607          */
608         public static function getReceiverForActor($actor, $tags)
609         {
610                 $receivers = [];
611                 $networks = Protocol::FEDERATED;
612                 $condition = ['nurl' => Strings::normaliseLink($actor), 'rel' => [Contact::SHARING, Contact::FRIEND, Contact::FOLLOWER],
613                         'network' => $networks, 'archive' => false, 'pending' => false];
614                 $contacts = DBA::select('contact', ['uid', 'rel'], $condition);
615                 while ($contact = DBA::fetch($contacts)) {
616                         if (self::isValidReceiverForActor($contact, $actor, $tags)) {
617                                 $receivers['uid:' . $contact['uid']] = $contact['uid'];
618                         }
619                 }
620                 DBA::close($contacts);
621                 return $receivers;
622         }
623
624         /**
625          * Tests if the contact is a valid receiver for this actor
626          *
627          * @param array  $contact
628          * @param string $actor
629          * @param array  $tags
630          *
631          * @return bool with receivers (user id)
632          * @throws \Exception
633          */
634         private static function isValidReceiverForActor($contact, $actor, $tags)
635         {
636                 // Public contacts are no valid receiver
637                 if ($contact['uid'] == 0) {
638                         return false;
639                 }
640
641                 // Are we following the contact? Then this is a valid receiver
642                 if (in_array($contact['rel'], [Contact::SHARING, Contact::FRIEND])) {
643                         return true;
644                 }
645
646                 // When the possible receiver isn't a community, then it is no valid receiver
647                 $owner = User::getOwnerDataById($contact['uid']);
648                 if (empty($owner) || ($owner['contact-type'] != Contact::TYPE_COMMUNITY)) {
649                         return false;
650                 }
651
652                 // Is the community account tagged?
653                 foreach ($tags as $tag) {
654                         if ($tag['type'] != 'Mention') {
655                                 continue;
656                         }
657
658                         if ($tag['href'] == $owner['url']) {
659                                 return true;
660                         }
661                 }
662
663                 return false;
664         }
665
666         /**
667          * Switches existing contacts to ActivityPub
668          *
669          * @param integer $cid Contact ID
670          * @param integer $uid User ID
671          * @param string  $url Profile URL
672          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
673          * @throws \ImagickException
674          */
675         public static function switchContact($cid, $uid, $url)
676         {
677                 if (DBA::exists('contact', ['id' => $cid, 'network' => Protocol::ACTIVITYPUB])) {
678                         Logger::info('Contact is already ActivityPub', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
679                         return;
680                 }
681
682                 if (Contact::updateFromProbe($cid, '', true)) {
683                         Logger::info('Update was successful', ['id' => $cid, 'uid' => $uid, 'url' => $url]);
684                 }
685
686                 // Send a new follow request to be sure that the connection still exists
687                 if (($uid != 0) && DBA::exists('contact', ['id' => $cid, 'rel' => [Contact::SHARING, Contact::FRIEND], 'network' => Protocol::ACTIVITYPUB])) {
688                         Logger::info('Contact had been switched to ActivityPub. Sending a new follow request.', ['uid' => $uid, 'url' => $url]);
689                         ActivityPub\Transmitter::sendActivity('Follow', $url, $uid);
690                 }
691         }
692
693         /**
694          *
695          *
696          * @param $receivers
697          * @param $actor
698          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
699          * @throws \ImagickException
700          */
701         private static function switchContacts($receivers, $actor)
702         {
703                 if (empty($actor)) {
704                         return;
705                 }
706
707                 foreach ($receivers as $receiver) {
708                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'nurl' => Strings::normaliseLink($actor)]);
709                         if (DBA::isResult($contact)) {
710                                 self::switchContact($contact['id'], $receiver, $actor);
711                         }
712
713                         $contact = DBA::selectFirst('contact', ['id'], ['uid' => $receiver, 'network' => Protocol::OSTATUS, 'alias' => [Strings::normaliseLink($actor), $actor]]);
714                         if (DBA::isResult($contact)) {
715                                 self::switchContact($contact['id'], $receiver, $actor);
716                         }
717                 }
718         }
719
720         /**
721          *
722          *
723          * @param       $object_data
724          * @param array $activity
725          *
726          * @return mixed
727          */
728         private static function addActivityFields($object_data, $activity)
729         {
730                 if (!empty($activity['published']) && empty($object_data['published'])) {
731                         $object_data['published'] = JsonLD::fetchElement($activity, 'as:published', '@value');
732                 }
733
734                 if (!empty($activity['diaspora:guid']) && empty($object_data['diaspora:guid'])) {
735                         $object_data['diaspora:guid'] = JsonLD::fetchElement($activity, 'diaspora:guid', '@value');
736                 }
737
738                 $object_data['service'] = JsonLD::fetchElement($activity, 'as:instrument', 'as:name', '@type', 'as:Service');
739                 $object_data['service'] = JsonLD::fetchElement($object_data, 'service', '@value');
740
741                 if (!empty($object_data['object_id'])) {
742                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
743                         $objectId = Item::getURIByLink($object_data['object_id']);
744                         if (!empty($objectId) && ($object_data['object_id'] != $objectId)) {
745                                 Logger::notice('Fix wrong object-id', ['received' => $object_data['object_id'], 'correct' => $objectId]);
746                                 $object_data['object_id'] = $objectId;
747                         }
748                 }
749
750                 return $object_data;
751         }
752
753         /**
754          * Fetches the object data from external ressources if needed
755          *
756          * @param string  $object_id    Object ID of the the provided object
757          * @param array   $object       The provided object array
758          * @param boolean $trust_source Do we trust the provided object?
759          * @param integer $uid          User ID for the signature that we use to fetch data
760          *
761          * @return array|false with trusted and valid object data
762          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
763          * @throws \ImagickException
764          */
765         private static function fetchObject(string $object_id, array $object = [], bool $trust_source = false, int $uid = 0)
766         {
767                 // By fetching the type we check if the object is complete.
768                 $type = JsonLD::fetchElement($object, '@type');
769
770                 if (!$trust_source || empty($type)) {
771                         $data = ActivityPub::fetchContent($object_id, $uid);
772                         if (!empty($data)) {
773                                 $object = JsonLD::compact($data);
774                                 Logger::log('Fetched content for ' . $object_id, Logger::DEBUG);
775                         } else {
776                                 Logger::log('Empty content for ' . $object_id . ', check if content is available locally.', Logger::DEBUG);
777
778                                 $item = Item::selectFirst([], ['uri' => $object_id]);
779                                 if (!DBA::isResult($item)) {
780                                         Logger::log('Object with url ' . $object_id . ' was not found locally.', Logger::DEBUG);
781                                         return false;
782                                 }
783                                 Logger::log('Using already stored item for url ' . $object_id, Logger::DEBUG);
784                                 $data = ActivityPub\Transmitter::createNote($item);
785                                 $object = JsonLD::compact($data);
786                         }
787                 } else {
788                         Logger::log('Using original object for url ' . $object_id, Logger::DEBUG);
789                 }
790
791                 $type = JsonLD::fetchElement($object, '@type');
792
793                 if (empty($type)) {
794                         Logger::log('Empty type', Logger::DEBUG);
795                         return false;
796                 }
797
798                 if (in_array($type, self::CONTENT_TYPES)) {
799                         $object_data = self::processObject($object);
800
801                         if (!empty($data)) {
802                                 $object_data['raw'] = json_encode($data);
803                         }
804                         return $object_data;
805                 }
806
807                 if ($type == 'as:Announce') {
808                         $object_id = JsonLD::fetchElement($object, 'object', '@id');
809                         if (empty($object_id) || !is_string($object_id)) {
810                                 return false;
811                         }
812                         return self::fetchObject($object_id, [], false, $uid);
813                 }
814
815                 Logger::log('Unhandled object type: ' . $type, Logger::DEBUG);
816                 return false;
817         }
818
819         /**
820          * Convert tags from JSON-LD format into a simplified format
821          *
822          * @param array $tags Tags in JSON-LD format
823          *
824          * @return array with tags in a simplified format
825          */
826         private static function processTags(array $tags)
827         {
828                 $taglist = [];
829
830                 foreach ($tags as $tag) {
831                         if (empty($tag)) {
832                                 continue;
833                         }
834
835                         $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
836                                 'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
837                                 'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
838
839                         if (empty($element['type'])) {
840                                 continue;
841                         }
842
843                         if (empty($element['href'])) {
844                                 $element['href'] = $element['name'];
845                         }
846
847                         $taglist[] = $element;
848                 }
849                 return $taglist;
850         }
851
852         /**
853          * Convert emojis from JSON-LD format into a simplified format
854          *
855          * @param array $emojis
856          * @return array with emojis in a simplified format
857          */
858         private static function processEmojis(array $emojis)
859         {
860                 $emojilist = [];
861
862                 foreach ($emojis as $emoji) {
863                         if (empty($emoji) || (JsonLD::fetchElement($emoji, '@type') != 'toot:Emoji') || empty($emoji['as:icon'])) {
864                                 continue;
865                         }
866
867                         $url = JsonLD::fetchElement($emoji['as:icon'], 'as:url', '@id');
868                         $element = ['name' => JsonLD::fetchElement($emoji, 'as:name', '@value'),
869                                 'href' => $url];
870
871                         $emojilist[] = $element;
872                 }
873
874                 return $emojilist;
875         }
876
877         /**
878          * Convert attachments from JSON-LD format into a simplified format
879          *
880          * @param array $attachments Attachments in JSON-LD format
881          *
882          * @return array with attachmants in a simplified format
883          */
884         private static function processAttachments(array $attachments)
885         {
886                 $attachlist = [];
887
888                 // Removes empty values
889                 $attachments = array_filter($attachments);
890
891                 foreach ($attachments as $attachment) {
892                         switch (JsonLD::fetchElement($attachment, '@type')) {
893                                 case 'as:Page':
894                                         $pageUrl = null;
895                                         $pageImage = null;
896
897                                         $urls = JsonLD::fetchElementArray($attachment, 'as:url');
898                                         foreach ($urls as $url) {
899                                                 // Single scalar URL case
900                                                 if (is_string($url)) {
901                                                         $pageUrl = $url;
902                                                         continue;
903                                                 }
904
905                                                 $href = JsonLD::fetchElement($url, 'as:href', '@id');
906                                                 $mediaType = JsonLD::fetchElement($url, 'as:mediaType', '@value');
907                                                 if (Strings::startsWith($mediaType, 'image')) {
908                                                         $pageImage = $href;
909                                                 } else {
910                                                         $pageUrl = $href;
911                                                 }
912                                         }
913
914                                         $attachlist[] = [
915                                                 'type'  => 'link',
916                                                 'title' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
917                                                 'desc'  => JsonLD::fetchElement($attachment, 'as:summary', '@value'),
918                                                 'url'   => $pageUrl,
919                                                 'image' => $pageImage,
920                                         ];
921                                         break;
922                                 case 'as:Link':
923                                         $attachlist[] = [
924                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
925                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
926                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
927                                                 'url' => JsonLD::fetchElement($attachment, 'as:href', '@id')
928                                         ];
929                                         break;
930                                 default:
931                                         $attachlist[] = [
932                                                 'type' => str_replace('as:', '', JsonLD::fetchElement($attachment, '@type')),
933                                                 'mediaType' => JsonLD::fetchElement($attachment, 'as:mediaType', '@value'),
934                                                 'name' => JsonLD::fetchElement($attachment, 'as:name', '@value'),
935                                                 'url' => JsonLD::fetchElement($attachment, 'as:url', '@id')
936                                         ];
937                         }
938                 }
939
940                 return $attachlist;
941         }
942
943         /**
944          * Fetch the original source or content with the "language" Markdown or HTML
945          *
946          * @param array $object
947          * @param array $object_data
948          *
949          * @return array
950          * @throws \Exception
951          */
952         private static function getSource($object, $object_data)
953         {
954                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/bbcode');
955                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
956                 if (!empty($object_data['source'])) {
957                         return $object_data;
958                 }
959
960                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/markdown');
961                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
962                 if (!empty($object_data['source'])) {
963                         $object_data['source'] = Markdown::toBBCode($object_data['source']);
964                         return $object_data;
965                 }
966
967                 $object_data['source'] = JsonLD::fetchElement($object, 'as:source', 'as:content', 'as:mediaType', 'text/html');
968                 $object_data['source'] = JsonLD::fetchElement($object_data, 'source', '@value');
969                 if (!empty($object_data['source'])) {
970                         $object_data['source'] = HTML::toBBCode($object_data['source']);
971                         return $object_data;
972                 }
973
974                 return $object_data;
975         }
976
977         /**
978          * Check if the "as:url" element is an array with multiple links
979          * This is the case with audio and video posts.
980          * Then the links are added as attachments
981          *
982          * @param array $object      The raw object
983          * @param array $object_data The parsed object data for later processing
984          * @return array the object data
985          */
986         private static function processAttachmentUrls(array $object, array $object_data) {
987                 // Check if this is some url with multiple links
988                 if (empty($object['as:url'])) {
989                         return $object_data;
990                 }
991                 
992                 $urls = $object['as:url'];
993                 $keys = array_keys($urls);
994                 if (!is_numeric(array_pop($keys))) {
995                         return $object_data;
996                 }
997
998                 $attachments = [];
999
1000                 foreach ($urls as $url) {
1001                         if (empty($url['@type']) || ($url['@type'] != 'as:Link')) {
1002                                 continue;
1003                         }
1004
1005                         $href = JsonLD::fetchElement($url, 'as:href', '@id');
1006                         if (empty($href)) {
1007                                 continue;
1008                         }
1009
1010                         $mediatype = JsonLD::fetchElement($url, 'as:mediaType');
1011                         if (empty($mediatype)) {
1012                                 continue;
1013                         }
1014
1015                         if ($mediatype == 'text/html') {
1016                                 $object_data['alternate-url'] = $href;
1017                         }
1018
1019                         $filetype = strtolower(substr($mediatype, 0, strpos($mediatype, '/')));
1020
1021                         if ($filetype == 'audio') {
1022                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href];
1023                         } elseif ($filetype == 'video') {
1024                                 $height = (int)JsonLD::fetchElement($url, 'as:height', '@value');
1025
1026                                 // We save bandwidth by using a moderate height
1027                                 // Peertube normally uses these heights: 240, 360, 480, 720, 1080
1028                                 if (!empty($attachments[$filetype]['height']) &&
1029                                         (($height > 480) || $height < $attachments[$filetype]['height'])) {
1030                                         continue;
1031                                 }
1032
1033                                 $attachments[$filetype] = ['type' => $mediatype, 'url' => $href, 'height' => $height];
1034                         }
1035                 }
1036
1037                 foreach ($attachments as $type => $attachment) {
1038                         $object_data['attachments'][] = ['type' => $type,
1039                                 'mediaType' => $attachment['type'],
1040                                 'name' => '',
1041                                 'url' => $attachment['url']];
1042                 }
1043                 return $object_data;
1044         }
1045
1046         /**
1047          * Fetches data from the object part of an activity
1048          *
1049          * @param array $object
1050          *
1051          * @return array
1052          * @throws \Exception
1053          */
1054         private static function processObject($object)
1055         {
1056                 if (!JsonLD::fetchElement($object, '@id')) {
1057                         return false;
1058                 }
1059
1060                 $object_data = [];
1061                 $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
1062                 $object_data['id'] = JsonLD::fetchElement($object, '@id');
1063                 $object_data['reply-to-id'] = JsonLD::fetchElement($object, 'as:inReplyTo', '@id');
1064
1065                 // An empty "id" field is translated to "./" by the compactor, so we have to check for this content
1066                 if (empty($object_data['reply-to-id']) || ($object_data['reply-to-id'] == './')) {
1067                         $object_data['reply-to-id'] = $object_data['id'];
1068                 } else {
1069                         // Some systems (e.g. GNU Social) don't reply to the "id" field but the "uri" field.
1070                         $replyToId = Item::getURIByLink($object_data['reply-to-id']);
1071                         if (!empty($replyToId) && ($object_data['reply-to-id'] != $replyToId)) {
1072                                 Logger::notice('Fix wrong reply-to', ['received' => $object_data['reply-to-id'], 'correct' => $replyToId]);
1073                                 $object_data['reply-to-id'] = $replyToId;
1074                         }
1075                 }
1076
1077                 $object_data['published'] = JsonLD::fetchElement($object, 'as:published', '@value');
1078                 $object_data['updated'] = JsonLD::fetchElement($object, 'as:updated', '@value');
1079
1080                 if (empty($object_data['updated'])) {
1081                         $object_data['updated'] = $object_data['published'];
1082                 }
1083
1084                 if (empty($object_data['published']) && !empty($object_data['updated'])) {
1085                         $object_data['published'] = $object_data['updated'];
1086                 }
1087
1088                 $actor = JsonLD::fetchElement($object, 'as:attributedTo', '@id');
1089                 if (empty($actor)) {
1090                         $actor = JsonLD::fetchElement($object, 'as:actor', '@id');
1091                 }
1092
1093                 $location = JsonLD::fetchElement($object, 'as:location', 'as:name', '@type', 'as:Place');
1094                 $location = JsonLD::fetchElement($location, 'location', '@value');
1095                 if ($location) {
1096                         // Some AP software allow formatted text in post location, so we run all the text converters we have to boil
1097                         // down to HTML and then finally format to plaintext.
1098                         $location = Markdown::convert($location);
1099                         $location = BBCode::convert($location);
1100                         $location = HTML::toPlaintext($location);
1101                 }
1102
1103                 $object_data['sc:identifier'] = JsonLD::fetchElement($object, 'sc:identifier', '@value');
1104                 $object_data['diaspora:guid'] = JsonLD::fetchElement($object, 'diaspora:guid', '@value');
1105                 $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
1106                 $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
1107                 $object_data['actor'] = $object_data['author'] = $actor;
1108                 $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
1109                 $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
1110                 $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
1111                 $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
1112                 $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
1113                 $object_data['content'] = JsonLD::fetchElement($object, 'as:content', '@value');
1114                 $object_data = self::getSource($object, $object_data);
1115                 $object_data['start-time'] = JsonLD::fetchElement($object, 'as:startTime', '@value');
1116                 $object_data['end-time'] = JsonLD::fetchElement($object, 'as:endTime', '@value');
1117                 $object_data['location'] = $location;
1118                 $object_data['latitude'] = JsonLD::fetchElement($object, 'as:location', 'as:latitude', '@type', 'as:Place');
1119                 $object_data['latitude'] = JsonLD::fetchElement($object_data, 'latitude', '@value');
1120                 $object_data['longitude'] = JsonLD::fetchElement($object, 'as:location', 'as:longitude', '@type', 'as:Place');
1121                 $object_data['longitude'] = JsonLD::fetchElement($object_data, 'longitude', '@value');
1122                 $object_data['attachments'] = self::processAttachments(JsonLD::fetchElementArray($object, 'as:attachment') ?? []);
1123                 $object_data['tags'] = self::processTags(JsonLD::fetchElementArray($object, 'as:tag') ?? []);
1124                 $object_data['emojis'] = self::processEmojis(JsonLD::fetchElementArray($object, 'as:tag', 'toot:Emoji') ?? []);
1125                 $object_data['generator'] = JsonLD::fetchElement($object, 'as:generator', 'as:name', '@type', 'as:Application');
1126                 $object_data['generator'] = JsonLD::fetchElement($object_data, 'generator', '@value');
1127                 $object_data['alternate-url'] = JsonLD::fetchElement($object, 'as:url', '@id');
1128
1129                 // Special treatment for Hubzilla links
1130                 if (is_array($object_data['alternate-url'])) {
1131                         $object_data['alternate-url'] = JsonLD::fetchElement($object_data['alternate-url'], 'as:href', '@id');
1132
1133                         if (!is_string($object_data['alternate-url'])) {
1134                                 $object_data['alternate-url'] = JsonLD::fetchElement($object['as:url'], 'as:href', '@id');
1135                         }
1136                 }
1137
1138                 if (in_array($object_data['object_type'], ['as:Audio', 'as:Video'])) {
1139                         $object_data = self::processAttachmentUrls($object, $object_data);
1140                 }
1141
1142                 $object_data['receiver'] = self::getReceivers($object, $object_data['actor'], $object_data['tags'], true);
1143                 $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
1144                 unset($object_data['receiver']['uid:-1']);
1145
1146                 // Common object data:
1147
1148                 // Unhandled
1149                 // @context, type, actor, signature, mediaType, duration, replies, icon
1150
1151                 // Also missing: (Defined in the standard, but currently unused)
1152                 // audience, preview, endTime, startTime, image
1153
1154                 // Data in Notes:
1155
1156                 // Unhandled
1157                 // contentMap, announcement_count, announcements, context_id, likes, like_count
1158                 // inReplyToStatusId, shares, quoteUrl, statusnetConversationId
1159
1160                 // Data in video:
1161
1162                 // To-Do?
1163                 // category, licence, language, commentsEnabled
1164
1165                 // Unhandled
1166                 // views, waitTranscoding, state, support, subtitleLanguage
1167                 // likes, dislikes, shares, comments
1168
1169                 return $object_data;
1170         }
1171 }