]> git.mxchange.org Git - friendica.git/blobdiff - src/Protocol/ActivityPub/Receiver.php
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[friendica.git] / src / Protocol / ActivityPub / Receiver.php
index c05f3c332e178009c5a9dec4d2936fc5e92c2917..a18a1092848a366bd878408dc1568d577f007d00 100644 (file)
@@ -1,6 +1,6 @@
 <?php
 /**
- * @copyright Copyright (C) 2010-2022, the Friendica project
+ * @copyright Copyright (C) 2010-2023, the Friendica project
  *
  * @license GNU AGPL version 3 or any later version
  *
@@ -63,7 +63,7 @@ class Receiver
        const PUBLIC_COLLECTION = 'as:Public';
        const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
        const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event', 'as:Audio', 'as:Page', 'as:Question'];
-       const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
+       const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept', 'as:View', 'as:Read', 'litepub:EmojiReact'];
 
        const TARGET_UNKNOWN = 0;
        const TARGET_TO = 1;
@@ -74,11 +74,11 @@ class Receiver
        const TARGET_ANSWER = 6;
        const TARGET_GLOBAL = 7;
 
-       const COMPLETION_NONE    = 0;
-       const COMPLETION_ANNOUCE = 1;
-       const COMPLETION_RELAY   = 2;
-       const COMPLETION_MANUAL  = 3;
-       const COMPLETION_AUTO    = 4;
+       const COMPLETION_NONE     = 0;
+       const COMPLETION_ANNOUNCE = 1;
+       const COMPLETION_RELAY    = 2;
+       const COMPLETION_MANUAL   = 3;
+       const COMPLETION_AUTO     = 4;
 
        /**
         * Checks incoming message from the inbox
@@ -122,20 +122,21 @@ class Receiver
 
                $http_signer = HTTPSignature::getSigner($body, $header);
                if ($http_signer === false) {
-                       Logger::warning('Invalid HTTP signature, message will be discarded.', ['uid' => $uid, 'actor' => $actor, 'header' => $header, 'body' => $body]);
-                       return;
+                       Logger::notice('Invalid HTTP signature, message will not be trusted.', ['uid' => $uid, 'actor' => $actor, 'header' => $header, 'body' => $body]);
+                       $signer = [];
                } elseif (empty($http_signer)) {
                        Logger::info('Signer is a tombstone. The message will be discarded, the signer account is deleted.');
                        return;
                } else {
                        Logger::info('Valid HTTP signature', ['signer' => $http_signer]);
+                       $signer = [$http_signer];
                }
 
-               $signer = [$http_signer];
-
                Logger::info('Message for user ' . $uid . ' is from actor ' . $actor);
 
-               if (LDSignature::isSigned($activity)) {
+               if ($http_signer === false) {
+                       $trust_source = false;
+               } elseif (LDSignature::isSigned($activity)) {
                        $ld_signer = LDSignature::getSigner($activity);
                        if (empty($ld_signer)) {
                                Logger::info('Invalid JSON-LD signature from ' . $actor);
@@ -208,7 +209,7 @@ class Receiver
                                Logger::notice('No object data found', ['type' => $type, 'object_type' => $object_type, 'object_id' => $object_id, 'actor' => $actor, 'activity' => $activity]);
                                return;
                        }
-       
+
                        if (self::routeActivities($object_data, $type, true)) {
                                Logger::debug('Handled activity', ['type' => $type, 'object_type' => $object_type, 'object_id' => $object_id, 'actor' => $actor]);
                        } else {
@@ -247,14 +248,14 @@ class Receiver
         * Fetches the object type for a given object id
         *
         * @param array   $activity
-        * @param string  $object_id Object ID of the the provided object
+        * @param string  $object_id Object ID of the provided object
         * @param integer $uid       User ID
         *
         * @return string with object type or NULL
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
-       private static function fetchObjectType(array $activity, string $object_id, int $uid = 0)
+       public static function fetchObjectType(array $activity, string $object_id, int $uid = 0)
        {
                if (!empty($activity['as:object'])) {
                        $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
@@ -263,7 +264,7 @@ class Receiver
                        }
                }
 
-               if (Post::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
+               if (Post::exists(['uri' => $object_id, 'gravity' => [Item::GRAVITY_PARENT, Item::GRAVITY_COMMENT]])) {
                        // We just assume "note" since it doesn't make a difference for the further processing
                        return 'as:Note';
                }
@@ -314,12 +315,15 @@ class Receiver
                        $object_type = JsonLD::fetchElement($activity['as:object'], '@type');
                }
 
+               $fetched = false;
+
                if (!empty($id) && !$trust_source) {
                        $fetch_uid = $uid ?: self::getBestUserForActivity($activity);
 
                        $fetched_activity = Processor::fetchCachedActivity($fetch_id, $fetch_uid);
                        if (!empty($fetched_activity)) {
-                               $object = JsonLD::compact($fetched_activity);
+                               $fetched = true;
+                               $object  = JsonLD::compact($fetched_activity);
 
                                $fetched_id   = JsonLD::fetchElement($object, '@id');
                                $fetched_type = JsonLD::fetchElement($object, '@type');
@@ -350,7 +354,7 @@ class Receiver
                $type = JsonLD::fetchElement($activity, '@type');
 
                // Fetch all receivers from to, cc, bto and bcc
-               $receiverdata = self::getReceivers($activity, $actor);
+               $receiverdata = self::getReceivers($activity, $actor, [], false, $push || $fetched);
                $receivers = $reception_types = [];
                foreach ($receiverdata as $key => $data) {
                        $receivers[$key] = $data['uid'];
@@ -405,23 +409,27 @@ class Receiver
                }
 
                // Any activities on account types must not be altered
-               if (in_array($object_type, self::ACCOUNT_TYPES)) {
+               if (in_array($type, ['as:Flag'])) {
+                       $object_data = [];
+                       $object_data['id'] = JsonLD::fetchElement($activity, '@id');
+                       $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
+                       $object_data['object_ids'] = JsonLD::fetchElementArray($activity, 'as:object', '@id');
+                       $object_data['content'] = JsonLD::fetchElement($activity, 'as:content', '@type');
+               } elseif (in_array($object_type, self::ACCOUNT_TYPES)) {
                        $object_data = [];
                        $object_data['id'] = JsonLD::fetchElement($activity, '@id');
                        $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
                        $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
                        $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
                        $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
-                       $object_data['push'] = $push;
                        if (!$trust_source && ($type == 'as:Delete')) {
                                $apcontact = APContact::getByURL($object_data['object_id'], true);
                                $trust_source = empty($apcontact) || ($apcontact['type'] == 'Tombstone') || $apcontact['suspended'];
                        }
-               } elseif (in_array($type, ['as:Create', 'as:Update', 'as:Announce', 'as:Invite']) || strpos($type, '#emojiReaction')) {
+               } elseif (in_array($type, ['as:Create', 'as:Update', 'as:Invite']) || strpos($type, '#emojiReaction')) {
                        // Fetch the content only on activities where this matters
                        // We can receive "#emojiReaction" when fetching content from Hubzilla systems
-                       // Always fetch on "Announce"
-                       $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source && ($type != 'as:Announce'), $fetch_uid);
+                       $object_data = self::fetchObject($object_id, $activity['as:object'], $trust_source, $fetch_uid);
                        if (empty($object_data)) {
                                Logger::info("Object data couldn't be processed");
                                return [];
@@ -429,19 +437,13 @@ class Receiver
 
                        $object_data['object_id'] = $object_id;
 
-                       if ($type == 'as:Announce') {
-                               $object_data['push'] = false;
-                       } else {
-                               $object_data['push'] = $push;
-                       }
-
                        // Test if it is an answer to a mail
                        if (DBA::exists('mail', ['uri' => $object_data['reply-to-id']])) {
                                $object_data['directmessage'] = true;
                        } else {
                                $object_data['directmessage'] = JsonLD::fetchElement($activity, 'litepub:directMessage');
                        }
-               } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Follow', 'litepub:EmojiReact', 'as:View'])) && in_array($object_type, self::CONTENT_TYPES)) {
+               } elseif (in_array($type, array_merge(self::ACTIVITY_TYPES, ['as:Announce', 'as:Follow'])) && in_array($object_type, self::CONTENT_TYPES)) {
                        // Create a mostly empty array out of the activity data (instead of the object).
                        // This way we later don't have to check for the existence of each individual array element.
                        $object_data = self::processObject($activity);
@@ -449,15 +451,13 @@ class Receiver
                        $object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
                        $object_data['object_id'] = $object_id;
                        $object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
-                       $object_data['push'] = $push;
-               } elseif (in_array($type, ['as:Add', 'as:Remove'])) {
+               } elseif (in_array($type, ['as:Add', 'as:Remove', 'as:Move'])) {
                        $object_data = [];
                        $object_data['id'] = JsonLD::fetchElement($activity, '@id');
                        $object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
                        $object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
                        $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
                        $object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
-                       $object_data['push'] = $push;
                } else {
                        $object_data = [];
                        $object_data['id'] = JsonLD::fetchElement($activity, '@id');
@@ -465,7 +465,6 @@ class Receiver
                        $object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor', '@id');
                        $object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
                        $object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
-                       $object_data['push'] = $push;
 
                        // An Undo is done on the object of an object, so we need that type as well
                        if (($type == 'as:Undo') && !empty($object_data['object_object'])) {
@@ -480,6 +479,8 @@ class Receiver
                        }
                }
 
+               $object_data['push'] = $push;
+
                $object_data = self::addActivityFields($object_data, $activity);
 
                if (empty($object_data['object_type'])) {
@@ -511,7 +512,10 @@ class Receiver
 //                     }
 //             }
 
-               Logger::info('Processing ' . $object_data['type'] . ' ' . $object_data['object_type'] . ' ' . $object_data['id']);
+               $account = Contact::selectFirstAccount(['platform'], ['nurl' => Strings::normaliseLink($actor)]);
+               $platform = $account['platform'] ?? '';
+
+               Logger::info('Processing', ['type' => $object_data['type'], 'object_type' => $object_data['object_type'], 'id' => $object_data['id'], 'actor' => $actor, 'platform' => $platform]);
 
                return $object_data;
        }
@@ -555,6 +559,11 @@ class Receiver
                        return true;
                }
 
+               if (!DI::config()->get('system', 'process_view') && ($type == 'as:View')) {
+                       Logger::info('View activities are ignored.', ['signer' => $signer, 'http_signer' => $http_signer]);
+                       return true;
+               }
+
                if (!JsonLD::fetchElement($activity, 'as:object', '@id')) {
                        Logger::info('Empty object', ['activity' => $activity]);
                        return true;
@@ -634,7 +643,9 @@ class Receiver
                        }
                }
 
-               if (DI::config()->get('system', 'decoupled_receiver') && ($trust_source || DI::config()->get('debug', 'ap_inbox_store_untrusted'))) {
+               $decouple = DI::config()->get('system', 'decoupled_receiver') && !in_array($completion, [self::COMPLETION_MANUAL, self::COMPLETION_ANNOUNCE]);
+
+               if ($decouple && ($trust_source || DI::config()->get('debug', 'ap_inbox_store_untrusted'))) {
                        $object_data = Queue::add($object_data, $type, $uid, $http_signer, $push, $trust_source);
                }
 
@@ -643,12 +654,12 @@ class Receiver
                        return true;
                }
 
-               if (!empty($object_data['entry-id']) && DI::config()->get('system', 'decoupled_receiver') && ($push || ($completion == self::COMPLETION_RELAY))) {
+               if (!empty($object_data['entry-id']) && $decouple && ($push || ($completion == self::COMPLETION_RELAY))) {
                        if (Queue::isProcessable($object_data['entry-id'])) {
                                // We delay by 5 seconds to allow to accumulate all receivers
                                $delayed = date(DateTimeFormat::MYSQL, time() + 5);
                                Logger::debug('Initiate processing', ['id' => $object_data['entry-id'], 'uri' => $object_data['object_id']]);
-                               $wid = Worker::add(['priority' => PRIORITY_HIGH, 'delayed' => $delayed], 'ProcessQueue', $object_data['entry-id']);
+                               $wid = Worker::add(['priority' => Worker::PRIORITY_HIGH, 'delayed' => $delayed], 'ProcessQueue', $object_data['entry-id']);
                                Queue::setWorkerId($object_data['entry-id'], $wid);
                        } else {
                                Logger::debug('Other queue entries need to be processed first.', ['id' => $object_data['entry-id']]);
@@ -660,11 +671,7 @@ class Receiver
                        $object_data['recursion-depth'] = $activity['recursion-depth'];
                }
 
-               if (in_array('as:Question', [$object_data['object_type'] ?? '', $object_data['object_object_type'] ?? ''])) {
-                       self::storeUnhandledActivity(false, $type, $object_data, $activity, $body, $uid, $trust_source, $push, $signer);
-               }
-
-               if (!self::routeActivities($object_data, $type, $push)) {
+               if (!self::routeActivities($object_data, $type, $push, true, $uid)) {
                        self::storeUnhandledActivity(true, $type, $object_data, $activity, $body, $uid, $trust_source, $push, $signer);
                        Queue::remove($object_data);
                }
@@ -678,13 +685,12 @@ class Receiver
         * @param string $type
         * @param bool   $push
         * @param bool   $fetch_parents
+        * @param int    $uid
         *
         * @return boolean Could the activity be routed?
         */
-       public static function routeActivities(array $object_data, string $type, bool $push, bool $fetch_parents = true): bool
+       public static function routeActivities(array $object_data, string $type, bool $push, bool $fetch_parents = true, int $uid = 0): bool
        {
-               $activity = $object_data['object_activity']     ?? [];
-
                switch ($type) {
                        case 'as:Create':
                                if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
@@ -693,6 +699,8 @@ class Receiver
                                } elseif (in_array($object_data['object_type'], ['pt:CacheFile'])) {
                                        // Unhandled Peertube activity
                                        Queue::remove($object_data);
+                               } elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
+                                       ActivityPub\Processor::updatePerson($object_data);
                                } else {
                                        return false;
                                }
@@ -712,8 +720,8 @@ class Receiver
                                        ActivityPub\Processor::addTag($object_data);
                                } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
                                        ActivityPub\Processor::addToFeaturedCollection($object_data);
-                               } elseif ($object_data['object_type'] == '') {
-                                       // The object type couldn't be determined. We don't have it and we can't fetch it. We ignore this activity.
+                               } elseif (in_array($object_data['object_type'], ['as:Tombstone', ''])) {
+                                       // We don't have the object here or it is deleted. We ignore this activity.
                                        Queue::remove($object_data);
                                } else {
                                        return false;
@@ -722,42 +730,24 @@ class Receiver
 
                        case 'as:Announce':
                                if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
-                                       $actor = JsonLD::fetchElement($activity, 'as:actor', '@id');
-                                       $object_data['thread-completion'] = Contact::getIdForURL($actor);
-                                       $object_data['completion-mode']   = self::COMPLETION_ANNOUCE;
-
-                                       if (!Post::exists(['uri' => $object_data['id'], 'uid' => 0])) {
-                                               $item = ActivityPub\Processor::createItem($object_data, $fetch_parents);
-                                               if (empty($item)) {
-                                                       Logger::debug('announced id was not created', ['id' => $object_data['id']]);
-                                                       return false;
+                                       if (!Item::searchByLink($object_data['object_id'], $uid)) {
+                                               if (ActivityPub\Processor::fetchMissingActivity($object_data['object_id'], [], $object_data['actor'], self::COMPLETION_ANNOUNCE, $uid)) {
+                                                       Logger::debug('Created announced id', ['uid' => $uid, 'id' => $object_data['object_id']]);
+                                                       Queue::remove($object_data);
+                                               } else {
+                                                       Logger::debug('Announced id was not created', ['uid' => $uid, 'id' => $object_data['object_id']]);
+                                                       Queue::remove($object_data);
+                                                       return true;
                                                }
-
-                                               $item['post-reason'] = Item::PR_ANNOUNCEMENT;
-                                               ActivityPub\Processor::postItem($object_data, $item);
-                                               Logger::debug('Created announced id', ['id' => $object_data['id']]);
                                        } else {
-                                               Logger::info('Announced id already exists', ['id' => $object_data['id']]);
+                                               Logger::info('Announced id already exists', ['uid' => $uid, 'id' => $object_data['object_id']]);
                                                Queue::remove($object_data);
                                        }
 
-                                       if (!empty($activity)) {
-                                               $announce_object_data = self::processObject($activity);
-                                               $announce_object_data['name'] = $type;
-                                               $announce_object_data['author'] = $actor;
-                                               $announce_object_data['object_id'] = $object_data['id'];
-                                               $announce_object_data['object_type'] = $object_data['object_type'];
-                                               $announce_object_data['push'] = $push;
-                                               Logger::debug('Create announce activity', ['id' => $announce_object_data['id'], 'object_data' => $announce_object_data]);
-
-                                               if (!empty($object_data['raw'])) {
-                                                       $announce_object_data['raw'] = $object_data['raw'];
-                                               }
-                                               if (!empty($object_data['raw-object'])) {
-                                                       $announce_object_data['raw-object'] = $object_data['raw-object'];
-                                               }
-                                               ActivityPub\Processor::createActivity($announce_object_data, Activity::ANNOUNCE);
-                                       }
+                                       ActivityPub\Processor::createActivity($object_data, Activity::ANNOUNCE);
+                               } elseif (in_array($object_data['object_type'], ['as:Tombstone', ''])) {
+                                       // We don't have the object here or it is deleted. We ignore this activity.
+                                       Queue::remove($object_data);
                                } else {
                                        return false;
                                }
@@ -766,8 +756,8 @@ class Receiver
                        case 'as:Like':
                                if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
                                        ActivityPub\Processor::createActivity($object_data, Activity::LIKE);
-                               } elseif ($object_data['object_type'] == '') {
-                                       // The object type couldn't be determined. We don't have it and we can't fetch it. We ignore this activity.
+                               } elseif (in_array($object_data['object_type'], ['as:Tombstone', ''])) {
+                                       // We don't have the object here or it is deleted. We ignore this activity.
                                        Queue::remove($object_data);
                                } else {
                                        return false;
@@ -777,8 +767,8 @@ class Receiver
                        case 'as:Dislike':
                                if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
                                        ActivityPub\Processor::createActivity($object_data, Activity::DISLIKE);
-                               } elseif ($object_data['object_type'] == '') {
-                                       // The object type couldn't be determined. We don't have it and we can't fetch it. We ignore this activity.
+                               } elseif (in_array($object_data['object_type'], ['as:Tombstone', ''])) {
+                                       // We don't have the object here or it is deleted. We ignore this activity.
                                        Queue::remove($object_data);
                                } else {
                                        return false;
@@ -819,6 +809,14 @@ class Receiver
                                }
                                break;
 
+                       case 'as:Move':
+                               if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
+                                       ActivityPub\Processor::movePerson($object_data);
+                               } else {
+                                       return false;
+                               }
+                               break;
+
                        case 'as:Block':
                                if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
                                        ActivityPub\Processor::blockAccount($object_data);
@@ -827,11 +825,19 @@ class Receiver
                                }
                                break;
 
+                       case 'as:Flag':
+                               if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
+                                       ActivityPub\Processor::ReportAccount($object_data);
+                               } else {
+                                       return false;
+                               }
+                               break;
+
                        case 'as:Remove':
                                if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
                                        ActivityPub\Processor::removeFromFeaturedCollection($object_data);
-                               } elseif ($object_data['object_type'] == '') {
-                                       // The object type couldn't be determined. We don't have it and we can't fetch it. We ignore this activity.
+                               } elseif (in_array($object_data['object_type'], ['as:Tombstone', ''])) {
+                                       // We don't have the object here or it is deleted. We ignore this activity.
                                        Queue::remove($object_data);
                                } else {
                                        return false;
@@ -851,9 +857,16 @@ class Receiver
 
                        case 'as:Accept':
                                if ($object_data['object_type'] == 'as:Follow') {
-                                       ActivityPub\Processor::acceptFollowUser($object_data);
+                                       if (!empty($object_data['object_actor'])) {
+                                               ActivityPub\Processor::acceptFollowUser($object_data);
+                                       } else {
+                                               Logger::notice('Unhandled "accept follow" message.', ['object_data' => $object_data]);
+                                       }
                                } elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
                                        ActivityPub\Processor::createActivity($object_data, Activity::ATTEND);
+                               } elseif (!empty($object_data['object_id']) && empty($object_data['object_actor']) && empty($object_data['object_type'])) {
+                                       // Follow acceptances from gup.pe only contain the object id
+                                       ActivityPub\Processor::acceptFollowUser($object_data);
                                } else {
                                        return false;
                                }
@@ -882,17 +895,23 @@ class Receiver
                                } elseif (($object_data['object_type'] == 'as:Block') &&
                                        in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
                                        ActivityPub\Processor::unblockAccount($object_data);
-                               } elseif (in_array($object_data['object_type'], array_merge(self::ACTIVITY_TYPES, ['as:Announce'])) &&
-                                       in_array($object_data['object_object_type'], array_merge(['as:Tombstone'], self::CONTENT_TYPES))) {
-                                       ActivityPub\Processor::undoActivity($object_data);
                                } elseif (in_array($object_data['object_type'], array_merge(self::ACTIVITY_TYPES, ['as:Announce', 'as:Create', ''])) &&
                                        empty($object_data['object_object_type'])) {
                                        // We cannot detect the target object. So we can ignore it.
                                        Queue::remove($object_data);
+                               } elseif (in_array($object_data['object_type'], array_merge(self::ACTIVITY_TYPES, ['as:Announce'])) &&
+                                       in_array($object_data['object_object_type'], array_merge(['as:Tombstone'], self::CONTENT_TYPES))) {
+                                       ActivityPub\Processor::undoActivity($object_data);
                                } elseif (in_array($object_data['object_type'], ['as:Create']) &&
                                        in_array($object_data['object_object_type'], ['pt:CacheFile'])) {
                                        // Unhandled Peertube activity
                                        Queue::remove($object_data);
+                               } elseif (in_array($object_data['object_type'], ['as:Delete'])) {
+                                       // We cannot undo deletions, so we just ignore this
+                                       Queue::remove($object_data);
+                               } elseif (in_array($object_data['object_object_type'], ['as:Tombstone'])) {
+                                       // The object is a tombstone, we ignore any actions on it.
+                                       Queue::remove($object_data);
                                } else {
                                        return false;
                                }
@@ -901,8 +920,18 @@ class Receiver
                        case 'as:View':
                                if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
                                        ActivityPub\Processor::createActivity($object_data, Activity::VIEW);
-                               } elseif ($object_data['object_type'] == '') {
-                                       // The object type couldn't be determined. Most likely we don't have it here. We ignore this activity.
+                               } elseif (in_array($object_data['object_type'], ['as:Tombstone', ''])) {
+                                       // We don't have the object here or it is deleted. We ignore this activity.
+                                       Queue::remove($object_data);
+                               } else {
+                                       return false;
+                               }
+                               break;
+                       case 'as:Read':
+                               if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
+                                       ActivityPub\Processor::createActivity($object_data, Activity::READ);
+                               } elseif (in_array($object_data['object_type'], ['as:Tombstone', ''])) {
+                                       // We don't have the object here or it is deleted. We ignore this activity.
                                        Queue::remove($object_data);
                                } else {
                                        return false;
@@ -912,8 +941,8 @@ class Receiver
                        case 'litepub:EmojiReact':
                                if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
                                        ActivityPub\Processor::createActivity($object_data, Activity::EMOJIREACT);
-                               } elseif ($object_data['object_type'] == '') {
-                                       // The object type couldn't be determined. We don't have it and we can't fetch it. We ignore this activity.
+                               } elseif (in_array($object_data['object_type'], ['as:Tombstone', ''])) {
+                                       // We don't have the object here or it is deleted. We ignore this activity.
                                        Queue::remove($object_data);
                                } else {
                                        return false;
@@ -959,7 +988,7 @@ class Receiver
 
                $tempfile = tempnam(System::getTempPath(), $file);
                file_put_contents($tempfile, json_encode(['activity' => $activity, 'body' => $body, 'uid' => $uid, 'trust_source' => $trust_source, 'push' => $push, 'signer' => $signer, 'object_data' => $object_data], JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_PRETTY_PRINT));
-               Logger::notice('Unknown activity stored', ['type' => $type, 'object_type' => $object_data['object_type'], $object_data['object_object_type'] ?? '', 'file' => $tempfile]);
+               Logger::notice('Unknown activity stored', ['type' => $type, 'object_type' => $object_data['object_type'], 'object_object_type' => $object_data['object_object_type'] ?? '', 'file' => $tempfile]);
        }
 
        /**
@@ -975,7 +1004,7 @@ class Receiver
                $uid = 0;
                $actor = JsonLD::fetchElement($activity, 'as:actor', '@id') ?? '';
 
-               $receivers = self::getReceivers($activity, $actor);
+               $receivers = self::getReceivers($activity, $actor, [], false, false);
                foreach ($receivers as $receiver) {
                        if ($receiver['type'] == self::TARGET_GLOBAL) {
                                return 0;
@@ -1008,6 +1037,10 @@ class Receiver
                        }
 
                        foreach ($receiver_list as $receiver) {
+                               if ($receiver == 'Public') {
+                                       Logger::warning('Not compacted public collection found', ['activity' => $activity, 'callstack' => System::callstack(20)]);
+                                       $receiver = ActivityPub::PUBLIC_COLLECTION;
+                               }
                                if ($receiver == self::PUBLIC_COLLECTION) {
                                        $receiver = ActivityPub::PUBLIC_COLLECTION;
                                }
@@ -1022,18 +1055,19 @@ class Receiver
         * Fetch the receiver list from an activity array
         *
         * @param array   $activity
-        * @param string  $actor
-        * @param array   $tags
-        * @param boolean $fetch_unlisted
+        * @param string $actor
+        * @param array  $tags
+        * @param bool   $fetch_unlisted
+        * @param bool   $push
         *
         * @return array with receivers (user id)
         * @throws \Exception
         */
-       private static function getReceivers(array $activity, string $actor, array $tags = [], bool $fetch_unlisted = false): array
+       private static function getReceivers(array $activity, string $actor, array $tags, bool $fetch_unlisted, bool $push): array
        {
                $reply = $receivers = $profile = [];
 
-               // When it is an answer, we inherite the receivers from the parent
+               // When it is an answer, we inherit the receivers from the parent
                $replyto = JsonLD::fetchElement($activity, 'as:inReplyTo', '@id');
                if (!empty($replyto)) {
                        $reply = [$replyto];
@@ -1051,18 +1085,13 @@ class Receiver
                        $reply[] = $object_id;
                }
 
-               if (!empty($reply)) {
-                       $parents = Post::select(['uid'], DBA::mergeConditions(['uri' => $reply], ["`uid` != ?", 0]));
-                       while ($parent = Post::fetch($parents)) {
-                               $receivers[$parent['uid']] = ['uid' => $parent['uid'], 'type' => self::TARGET_ANSWER];
-                       }
-                       DBA::close($parents);
-               }
-
                if (!empty($actor)) {
                        $profile   = APContact::getByURL($actor);
                        $followers = $profile['followers'] ?? '';
                        $is_forum  = ($actor['type'] ?? '') == 'Group';
+                       if ($push) {
+                               Contact::updateByUrlIfNeeded($actor);
+                       }
                        Logger::info('Got actor and followers', ['actor' => $actor, 'followers' => $followers]);
                } else {
                        Logger::info('Empty actor', ['activity' => $activity]);
@@ -1141,8 +1170,27 @@ class Receiver
                        }
                }
 
+               if (!empty($reply) && (!empty($receivers[0]) || !empty($receivers[-1]))) {
+                       $parents = Post::select(['uid'], DBA::mergeConditions(['uri' => $reply], ["`uid` != ?", 0]));
+                       while ($parent = Post::fetch($parents)) {
+                               $receivers[$parent['uid']] = ['uid' => $parent['uid'], 'type' => self::TARGET_ANSWER];
+                       }
+                       DBA::close($parents);
+               }
+
                self::switchContacts($receivers, $actor);
 
+               // "birdsitelive" is a service that mirrors tweets into the fediverse
+               // These posts can be fetched without authentification, but are not marked as public
+               // We treat them as unlisted posts to be able to handle them.
+               if (empty($receivers) && $fetch_unlisted && Contact::isPlatform($actor, 'birdsitelive')) {
+                       $receivers[0]  = ['uid' => 0, 'type' => self::TARGET_GLOBAL];
+                       $receivers[-1] = ['uid' => -1, 'type' => self::TARGET_GLOBAL];
+                       Logger::notice('Post from "birdsitelive" is set to "unlisted"', ['id' => JsonLD::fetchElement($activity, '@id')]);
+               } elseif (empty($receivers)) {
+                       Logger::notice('Post has got no receivers', ['fetch_unlisted' => $fetch_unlisted, 'actor' => $actor, 'id' => JsonLD::fetchElement($activity, '@id'), 'type' => JsonLD::fetchElement($activity, '@type')]);
+               }
+
                return $receivers;
        }
 
@@ -1324,7 +1372,7 @@ class Receiver
        /**
         * Fetches the object data from external ressources if needed
         *
-        * @param string  $object_id    Object ID of the the provided object
+        * @param string  $object_id    Object ID of the provided object
         * @param array   $object       The provided object array
         * @param boolean $trust_source Do we trust the provided object?
         * @param integer $uid          User ID for the signature that we use to fetch data
@@ -1398,14 +1446,6 @@ class Receiver
                        return $object_data;
                }
 
-               if ($type == 'as:Announce') {
-                       $object_id = JsonLD::fetchElement($object, 'object', '@id');
-                       if (empty($object_id) || !is_string($object_id)) {
-                               return false;
-                       }
-                       return self::fetchObject($object_id, [], false, $uid);
-               }
-
                Logger::info('Unhandled object type: ' . $type);
                return false;
        }
@@ -1448,7 +1488,7 @@ class Receiver
                                continue;
                        }
 
-                       $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type')),
+                       $element = ['type' => str_replace('as:', '', JsonLD::fetchElement($tag, '@type') ?? ''),
                                'href' => JsonLD::fetchElement($tag, 'as:href', '@id'),
                                'name' => JsonLD::fetchElement($tag, 'as:name', '@value')];
 
@@ -1813,6 +1853,35 @@ class Receiver
                        return false;
                }
 
+               $object_data = self::getObjectDataFromActivity($object);
+
+               $receiverdata = self::getReceivers($object, $object_data['actor'] ?? '', $object_data['tags'], true, false);
+               $receivers = $reception_types = [];
+               foreach ($receiverdata as $key => $data) {
+                       $receivers[$key] = $data['uid'];
+                       $reception_types[$data['uid']] = $data['type'] ?? 0;
+               }
+
+               $object_data['receiver_urls']  = self::getReceiverURL($object);
+               $object_data['receiver']       = $receivers;
+               $object_data['reception_type'] = $reception_types;
+
+               $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
+               unset($object_data['receiver'][-1]);
+               unset($object_data['reception_type'][-1]);
+
+               return $object_data;
+       }
+
+       /**
+        * Create an object data array from a given activity
+        *
+        * @param array $object
+        *
+        * @return array Object data
+        */
+       public static function getObjectDataFromActivity(array $object): array
+       {
                $object_data = [];
                $object_data['object_type'] = JsonLD::fetchElement($object, '@type');
                $object_data['id'] = JsonLD::fetchElement($object, '@id');
@@ -1823,7 +1892,7 @@ class Receiver
                        $object_data['reply-to-id'] = $object_data['id'];
 
                        // On activities the "reply to" is the id of the object it refers to
-                       if (in_array($object_data['object_type'], self::ACTIVITY_TYPES)) {
+                       if (in_array($object_data['object_type'], array_merge(self::ACTIVITY_TYPES, ['as:Announce']))) {
                                $object_id = JsonLD::fetchElement($object, 'as:object', '@id');
                                if (!empty($object_id)) {
                                        $object_data['reply-to-id'] = $object_id;
@@ -1868,8 +1937,10 @@ class Receiver
                $object_data['diaspora:comment'] = JsonLD::fetchElement($object, 'diaspora:comment', '@value');
                $object_data['diaspora:like'] = JsonLD::fetchElement($object, 'diaspora:like', '@value');
                $object_data['actor'] = $object_data['author'] = $actor;
-               $object_data['context'] = JsonLD::fetchElement($object, 'as:context', '@id');
-               $object_data['conversation'] = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
+               $element = JsonLD::fetchElement($object, 'as:context', '@id');
+               $object_data['context'] = $element != './' ? $element : null;
+               $element = JsonLD::fetchElement($object, 'ostatus:conversation', '@id');
+               $object_data['conversation'] = $element != './' ? $element : null;
                $object_data['sensitive'] = JsonLD::fetchElement($object, 'as:sensitive');
                $object_data['name'] = JsonLD::fetchElement($object, 'as:name', '@value');
                $object_data['summary'] = JsonLD::fetchElement($object, 'as:summary', '@value');
@@ -1909,6 +1980,24 @@ class Receiver
                        $object_data['attachments'] = array_merge($object_data['attachments'], self::processAttachmentUrls($object['as:url'] ?? []));
                }
 
+               // Support for quoted posts (Pleroma, Fedibird and Misskey)
+               $object_data['quote-url'] = JsonLD::fetchElement($object, 'as:quoteUrl', '@value');
+               if (empty($object_data['quote-url'])) {
+                       $object_data['quote-url'] = JsonLD::fetchElement($object, 'fedibird:quoteUri', '@value');
+               }
+               if (empty($object_data['quote-url'])) {
+                       $object_data['quote-url'] = JsonLD::fetchElement($object, 'misskey:_misskey_quote', '@value');
+               }
+
+               // Misskey adds some data to the standard "content" value for quoted posts for backwards compatibility.
+               // Their own "_misskey_content" value does then contain the content without this extra data.
+               if (!empty($object_data['quote-url'])) {
+                       $misskey_content = JsonLD::fetchElement($object, 'misskey:_misskey_content', '@value');
+                       if (!empty($misskey_content)) {
+                               $object_data['content'] = $misskey_content;
+                       }
+               }
+
                // For page types we expect that the alternate url posts to some page.
                // So we add this to the attachments if it differs from the id.
                // Currently only Lemmy is using the page type.
@@ -1921,21 +2010,6 @@ class Receiver
                        $object_data['question'] = self::processQuestion($object);
                }
 
-               $receiverdata = self::getReceivers($object, $object_data['actor'] ?? '', $object_data['tags'], true);
-               $receivers = $reception_types = [];
-               foreach ($receiverdata as $key => $data) {
-                       $receivers[$key] = $data['uid'];
-                       $reception_types[$data['uid']] = $data['type'] ?? 0;
-               }
-
-               $object_data['receiver_urls']  = self::getReceiverURL($object);
-               $object_data['receiver']       = $receivers;
-               $object_data['reception_type'] = $reception_types;
-
-               $object_data['unlisted'] = in_array(-1, $object_data['receiver']);
-               unset($object_data['receiver'][-1]);
-               unset($object_data['reception_type'][-1]);
-
                return $object_data;
        }