[AP] Support Private Messaging

ActivityPubPlugin:
- Subscribe DirectMessage events

Activitypub_inbox_handler:
- Update handle_create_note to create private messages

Activitypub_postman:
- Add create_direct_note for sending private messages

Activitypub_create:
- Update create_to_array to support the 'directMessage' attribute
- Add isPrivateNote to verify private activities

Activitypub_notice:
- Update create_note to support the 'directMessage' attribute
- Remove isPrivateNote

lib/models:
- Add Activitypub_message, the model in charge of private notes

plugins/ActivityPub/ActivityPubPlugin.php

@@ -286,6 +286,46 @@ class ActivityPubPlugin extends Plugin
         return true;
     }
 
+    /**
+     * Add AP-subscriptions for private messaging
+     *
+     * @param User $current current logged user
+     * @param array &$recipients
+     * @return void
+     */
+    public function onFillDirectMessageRecipients(User $current, array &$recipients): void {
+        try {
+            $subs = Activitypub_profile::getSubscribed($current->getProfile());
+            foreach ($subs as $sub) {
+                if (!$sub->isLocal()) { // AP plugin adds AP users
+                    try {
+                        $value = 'profile:'.$sub->getID();
+                        $recipients[$value] = substr($sub->getAcctUri(), 5) . " [{$sub->getBestName()}]";
+                    } catch (ProfileNoAcctUriException $e) {
+                        $recipients[$value] = "[?@?] " . $e->profile->getBestName();
+                    }
+                }
+            }
+        } catch (NoResultException $e) {
+            // let it go
+        }
+    }
+
+    /**
+     * Validate AP-recipients for profile page message action addition
+     * 
+     * @param Profile $recipient
+     * @return bool hook return value
+     */
+    public function onDirectMessageProfilePageActions(Profile $recipient): bool {
+        $to = Activitypub_profile::getKV('profile_id', $recipient->getID());
+        if ($to instanceof Activitypub_profile) {
+            return false; // we can validate this profile, signal it
+        }
+
+        return true;
+    }
+
     /**
      * Plugin Nodeinfo information
      *
@@ -815,12 +855,10 @@ class ActivityPubPlugin extends Plugin
             return true;
         }
 
-        // We handle things locally either because:
+        // Handle delete locally either because:
-        // 1. the deleting user has special permissions to do so,
+        // 1. There's no undo-share logic yet
-        //    but still doesn't own the notice
+        // 2. The deleting user has previleges to do so (locally)
-        // 2. the notice is an announce, and there's no undo-share
+        if ($notice->isRepeat() || ($notice->getProfile()->getID() != $profile->getID())) {
-        //    logic in GS's AP implementation
-        if (!$notice->isLocal() || $notice->isRepeat()) {
             return true;
         }
 
@@ -855,6 +893,29 @@ class ActivityPubPlugin extends Plugin
         return true;
     }
 
+    /**
+     * Federate private message
+     *
+     * @param Notice $message
+     * @return void
+     */
+    public function onSendDirectMessage(Notice $message): void {
+        $from = $message->getProfile();
+        if (!$from->isLocal()) {
+            // nothing to do
+            return;
+        }
+
+        $to = Activitypub_profile::from_profile_collection(
+            $message->getAttentionProfiles()
+        );
+
+        if (!empty($to)) {
+            $postman = new Activitypub_postman($from, $to);
+            $postman->create_direct_note($message);
+        }
+    }
+
     /**
      * Override the "from ActivityPub" bit in notice lists to link to the
      * original post and show the domain it came from.

plugins/ActivityPub/lib/inbox_handler.php

@@ -206,8 +206,8 @@ class Activitypub_inbox_handler
      */
     private function handle_create_note()
     {
-        if (Activitypub_notice::isPrivateNote($this->activity)) {
+        if (Activitypub_create::isPrivateNote($this->activity)) {
-            // Plugin DirectMessage must handle this
+            Activitypub_message::create_message($this->object, $this->actor);
         } else {
             Activitypub_notice::create_notice($this->object, $this->actor);
         }
@@ -226,8 +226,7 @@ class Activitypub_inbox_handler
             $object = $object['id'];
         }
 
-        // some moderator could already have deleted the
+        // Already deleted? (By some admin, perhaps?)
-        // notice, so we test it first
         try {
             $found = Deleted_notice::getByUri($object);
             $deleted = ($found instanceof Deleted_notice);

plugins/ActivityPub/lib/models/Activitypub_create.php

@@ -42,15 +42,16 @@ class Activitypub_create
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @param string $actor
      * @param array $object
+     * @param bool $directMesssage whether it is a private Create activity or not
      * @return array pretty array to be used in a response
      */
-    public static function create_to_array(string $actor, array $object): array
+    public static function create_to_array(string $actor, array $object, bool $directMessage = false): array
     {
         $res = [
             '@context'      => 'https://www.w3.org/ns/activitystreams',
             'id'            => $object['id'].'/create',
             'type'          => 'Create',
-            'directMessage' => false,
+            'directMessage' => $directMessage,
             'to'            => $object['to'],
             'cc'            => $object['cc'],
             'actor'         => $actor,
@@ -89,4 +90,21 @@ class Activitypub_create
                 throw new Exception('This is not a supported Object Type for Create Activity.');
         }
     }
+
+    /**
+     * Verify if received note is private (direct).
+     * Note that we're conformant with the (yet) non-standard directMessage attribute:
+     * https://github.com/w3c/activitypub/issues/196#issuecomment-304958984
+     *
+     * @param array $activity received Create-Note activity
+     * @return bool true if note is private, false otherwise
+     * @author Bruno casteleiro <brunoccast@fc.up.pt>
+     */
+    public static function isPrivateNote(array $activity): bool {
+        if (isset($activity['directMessage'])) {
+            return $activity['directMessage'];
+        }
+
+        return empty($activity['cc']) && !in_array('https://www.w3.org/ns/activitystreams#Public', $activity['to']);
+    }
 }

plugins/ActivityPub/lib/models/Activitypub_message.php

@@ -0,0 +1,91 @@
+<?php
+// This file is part of GNU social - https://www.gnu.org/software/social
+//
+// GNU social is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// GNU social is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with GNU social.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * ActivityPub implementation for GNU social
+ *
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @copyright 2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub direct note representation
+ *
+ * @author Bruno Casteleiro <brunoccast@fc.up.pt>
+ * @copyright 2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_message
+{
+    /**
+     * Generates a pretty message from a Notice object
+     *
+     * @param Notice $message
+     * @return array array to be used in a response
+     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
+     */
+    public static function message_to_array(Notice $message): array
+    {
+        $from = $message->getProfile();
+
+        $tags = [];
+        foreach ($message->getTags() as $tag) {
+            if ($tag != "") { // Hacky workaround to avoid stupid outputs
+                $tags[] = Activitypub_tag::tag_to_array($tag);
+            }
+        }
+
+        $to = [];
+        foreach ($message->getAttentionProfiles() as $to_profile) {
+            $to[]   = $href = $to_profile->getUri();
+            $tags[] = Activitypub_mention_tag::mention_tag_to_array_from_values($href, $to_profile->getNickname().'@'.parse_url($href, PHP_URL_HOST));
+        }
+
+        $item = [
+            '@context'      => 'https://www.w3.org/ns/activitystreams',
+            'id'            => common_local_url('showmessage', ['message' => $message->getID()]),
+            'type'          => 'Note',
+            'published'     => str_replace(' ', 'T', $message->created).'Z',
+            'attributedTo'  => ActivityPubPlugin::actor_uri($from),
+            'to'            => $to,
+            'cc'            => [],
+            'content'       => $message->getRendered(),
+            'attachment'    => [],
+            'tag'           => $tags
+        ];
+
+        return $item;
+    }
+
+    /**
+     * Create a private Notice via ActivityPub Note Object.
+     * Returns created Notice.
+     *
+     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
+     * @param array $object
+     * @param Profile $actor_profile
+     * @return Notice
+     * @throws Exception
+     */
+    public static function create_message(array $object, Profile $actor_profile = null): Notice
+    {
+        return Activitypub_notice::create_notice($object, $actor_profile, true);
+    }
+}

plugins/ActivityPub/lib/models/Activitypub_notice.php

@@ -118,10 +118,11 @@ class Activitypub_notice
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @param array $object
      * @param Profile $actor_profile
+     * @param bool $directMessage
      * @return Notice
      * @throws Exception
      */
-    public static function create_notice(array $object, Profile $actor_profile = null)
+    public static function create_notice(array $object, Profile $actor_profile = null, bool $directMessage = false): Notice
     {
         $id      = $object['id'];                                // int
         $url     = isset($object['url']) ? $object['url'] : $id; // string
@@ -154,6 +155,10 @@ class Activitypub_notice
                     'url'      => $url,
                     'is_local' => self::getNotePolicyType($object, $actor_profile)];
 
+        if ($directMessage) {
+            $options['scope'] = Notice::MESSAGE_SCOPE;
+        }
+
         // Is this a reply?
         if (isset($settings['inReplyTo'])) {
             try {
@@ -192,8 +197,10 @@ class Activitypub_notice
         unset($discovery);
 
         foreach ($mentions_profiles as $mp) {
+            if (!$mp->hasBlocked($actor_profile)) {
                 $act->context->attention[ActivityPubPlugin::actor_uri($mp)] = 'http://activitystrea.ms/schema/1.0/person';
             }
+        }
 
         // Add location if that is set
         if (isset($settings['latitude'], $settings['longitude'])) {
@@ -291,20 +298,4 @@ class Activitypub_notice
             return Notice::GATEWAY;
         }
     }
-
-    /**
-     * Verify if received note is private (direct).
-     * Note that we're conformant with the (yet) non-standard directMessage attribute:
-     * https://github.com/w3c/activitypub/issues/196#issuecomment-304958984
-     *
-     * @param array $activity received Create-Note activity
-     * @return bool true if note is private, false otherwise
-     */
-    public static function isPrivateNote(array $activity): bool {
-        if (isset($activity['directMessage'])) {
-            return $activity['directMessage'];
-        }
-
-        return empty($activity['cc']) && !in_array('https://www.w3.org/ns/activitystreams#Public', $activity['to']);
-    }
 }

plugins/ActivityPub/lib/postman.php

@@ -48,12 +48,12 @@ class Activitypub_postman
     /**
      * Create a postman to deliver something to someone
      *
-     * @param Profile $from Profile of sender
+     * @param Profile $from sender Profile
-     * @param $to
+     * @param array $to receiver Profiles
      * @throws Exception
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      */
-    public function __construct($from, $to)
+    public function __construct(Profile $from, array $to)
     {
         $this->actor = $from;
         $discovery = new Activitypub_explorer();
@@ -302,6 +302,37 @@ class Activitypub_postman
         }
     }
 
+    /**
+     * Send a Create direct-notification to remote instances
+     *
+     * @param Notice $message
+     * @author Bruno Casteleiro <brunoccast@fc.up.pt>
+     */
+    public function create_direct_note(Notice $message)
+    {
+        $data = Activitypub_create::create_to_array(
+            $this->actor_uri,
+            Activitypub_message::message_to_array($message),
+            true
+        );
+        $data = json_encode($data, JSON_UNESCAPED_SLASHES);
+
+        foreach ($this->to_inbox() as $inbox) {
+            $res = $this->send($data, $inbox);
+
+            // accummulate errors for later use, if needed
+            if (!($res->getStatus() == 200 || $res->getStatus() == 202 || $res->getStatus() == 409)) {
+                $res_body = json_decode($res->getBody(), true);
+                $errors[] = isset($res_body[0]['error']) ?
+                          $res_body[0]['error'] : "An unknown error occurred.";
+            }
+        }
+
+        if (!empty($errors)) {
+            common_log(LOG_ERR, sizeof($errors) . " instance/s failed to handle the create-note activity!");
+        }
+    }
+
     /**
      * Send a Announce notification to remote instances
      *
@@ -368,7 +399,7 @@ class Activitypub_postman
      * @author Diogo Cordeiro <diogo@fc.up.pt>
      * @return array To Inbox URLs
      */
-    private function to_inbox()
+    private function to_inbox(): array
     {
         $to_inboxes = [];
         foreach ($this->to as $to_profile) {