[CORE] Add ActivityPub plugin

This is not the same as the one in https://notabug.org/diogo/gnu-social-activitypub-plugin
Differences to the first "release"
-> Doesn't use guzzle nor has any composer dependencies
-> Supports HTTP Signatures
-> Has basic l10n/i18n
-> Some minor bug fixes

lib/default.php

@@ -352,6 +352,7 @@ $default =
                             'Embed' => array(),
                             'OpenID' => array(),
                             'OpportunisticQM' => array(),
+                            'ActivityPub' => array(),
                             'OStatus' => array(),
                             'Poll' => array(),
                             'SimpleCaptcha' => array(),

plugins/ActivityPub/CONTRIBUTING.md

@@ -0,0 +1,93 @@
+# Contributing
+
+When contributing to this repository, please first discuss the change you wish to make via issue,
+email, or any other method with the owners of this repository before making a change.
+
+Please note we have a code of conduct, please follow it in all your interactions with the project.
+
+# Coding Style
+- We follow every [PSR-2](https://www.php-fig.org/psr/psr-2/) ...
+- ... except camelCase, that's too bad, we use snake_case
+
+## Merge Request Process
+
+1. Ensure you strip any trailing spaces off
+2. Increase the version numbers in any examples files and the README.md to the new version that this
+   Pull Request would represent. The versioning scheme we use is [SemVer](http://semver.org/).
+3. You may merge the Pull Request in once you have the sign-off of two other developers, or if you
+   do not have permission to do that, you may request the second reviewer to merge it for you.
+
+## Code of Conduct
+
+### Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, gender identity and expression, level of experience,
+nationality, personal appearance, race, religion, or sexual identity and
+orientation.
+
+### Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+### Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+### Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project e-mail
+address, posting via an official social media account, or acting as an appointed
+representative at an online or offline event. Representation of a project may be
+further defined and clarified by project maintainers.
+
+### Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the project team at diogo@fc.up.pt. All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate to the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+### Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at [http://contributor-covenant.org/version/1/4][version]
+
+[homepage]: http://contributor-covenant.org
+[version]: http://contributor-covenant.org/version/1/4/

plugins/ActivityPub/COPYING

@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
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+specifically granted under this License.  You may not convey a covered
+work if you are a party to an arrangement with a third party that is
+in the business of distributing software, under which you make payment
+to the third party based on the extent of your activity of conveying
+the work, and under which the third party grants, to any of the
+parties who would receive the covered work from you, a discriminatory
+patent license (a) in connection with copies of the covered work
+conveyed by you (or copies made from those copies), or (b) primarily
+for and in connection with specific products or compilations that
+contain the covered work, unless you entered into that arrangement,
+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot convey a
+covered work so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you may
+not convey it at all.  For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.
+
+  13. Remote Network Interaction; Use with the GNU General Public License.
+
+  Notwithstanding any other provision of this License, if you modify the
+Program, your modified version must prominently offer all users
+interacting with it remotely through a computer network (if your version
+supports such interaction) an opportunity to receive the Corresponding
+Source of your version by providing access to the Corresponding Source
+from a network server at no charge, through some standard or customary
+means of facilitating copying of software.  This Corresponding Source
+shall include the Corresponding Source for any work covered by version 3
+of the GNU General Public License that is incorporated pursuant to the
+following paragraph.
+
+  Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU General Public License into a single
+combined work, and to convey the resulting work.  The terms of this
+License will continue to apply to the part which is the covered work,
+but the work with which it is combined will remain governed by version
+3 of the GNU General Public License.
+
+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
+the GNU Affero General Public License from time to time.  Such new versions
+will be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU Affero General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU Affero General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU Affero General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program 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.
+
+    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If your software can interact with users remotely through a computer
+network, you should also make sure that it provides a way for users to
+get its source.  For example, if your program is a web application, its
+interface could display a "Source" link that leads users to an archive
+of the code.  There are many ways you could offer source, and different
+solutions will be better for different programs; see section 13 for the
+specific requirements.
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU AGPL, see
+<http://www.gnu.org/licenses/>.

plugins/ActivityPub/README.md

@@ -0,0 +1,42 @@
+# ActivityPub plugin for GNU social
+(c) 2018-2019 Free Software Foundation, Inc
+
+This is the README file for GNU social's ActivityPub plugin.
+It includes general information about the plugin.
+
+## About
+
+This plugin adds [ActivityPub](https://www.w3.org/TR/activitypub/) support to GNU social.
+
+## Credits
+
+* **[Diogo Cordeiro](https://www.diogo.site/)**
+
+## Special thanks
+
+* **[Daniel Supernault](https://github.com/dansup)**
+* **[Mikael Nordfeldth](https://mmn-o.se/)**
+
+## License
+
+This program 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.
+
+This program 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 this program, in the file "COPYING".  If not, see
+<http://www.gnu.org/licenses/>.
+
+    IMPORTANT NOTE: The GNU Affero General Public License (AGPL) has
+    *different requirements* from the "regular" GPL. In particular, if
+    you make modifications to the plugin source code on your server,
+    you *MUST MAKE AVAILABLE* the modified version of the source code
+    to your users under the same license. This is a legal requirement
+    of using the software, and if you do not wish to share your
+    modifications, *YOU MAY NOT USE THIS PLUGIN*.

plugins/ActivityPub/actions/apactorfollowers.php

@@ -0,0 +1,134 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * Actor's Followers Collection
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class apActorFollowersAction extends ManagedAction
+{
+    protected $needLogin = false;
+    protected $canPost   = true;
+
+    /**
+     * Handle the Followers Collection request
+     *
+     * @return void
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    protected function handle()
+    {
+        try {
+            $profile = Profile::getByID($this->trimmed('id'));
+            $profile_id = $profile->getID();
+        } catch (Exception $e) {
+            ActivityPubReturn::error('Invalid Actor URI.', 404);
+        }
+
+        if (!$profile->isLocal()) {
+            ActivityPubReturn::error("This is not a local user.", 403);
+        }
+
+        if (!isset($_GET["page"])) {
+            $page = 0;
+        } else {
+            $page = intval($this->trimmed('page'));
+        }
+
+        if ($page < 0) {
+            ActivityPubReturn::error('Invalid page number.');
+        }
+
+        $since = ($page - 1) * PROFILES_PER_MINILIST;
+        $limit = (($page - 1) == 0 ? 1 : $page) * PROFILES_PER_MINILIST;
+
+        /* Calculate total items */
+        $total_subs  = $profile->subscriberCount();
+        $total_pages = ceil($total_subs / PROFILES_PER_MINILIST);
+
+        $res = [
+            '@context'     => [
+              "https://www.w3.org/ns/activitystreams",
+              "https://w3id.org/security/v1",
+            ],
+            'id'           => common_local_url('apActorFollowers', ['id' => $profile_id]).(($page != 0) ? '?page='.$page : ''),
+            'type'         => ($page == 0 ? 'OrderedCollection' : 'OrderedCollectionPage'),
+            'totalItems'   => $total_subs
+        ];
+
+        if ($page == 0) {
+            $res['first'] = common_local_url('apActorFollowers', ['id' => $profile_id]).'?page=1';
+        } else {
+            $res['orderedItems'] = $this->generate_followers($profile, $since, $limit);
+            $res['partOf'] = common_local_url('apActorFollowers', ['id' => $profile_id]);
+
+            if ($page+1 < $total_pages) {
+                $res['next'] = common_local_url('apActorFollowers', ['id' => $profile_id]).'page='.($page+1 == 1 ? 2 : $page+1);
+            }
+
+            if ($page > 1) {
+                $res['prev'] = common_local_url('apActorFollowers', ['id' => $profile_id]).'?page='.($page-1 <= 0 ? 1 : $page-1);
+            }
+        }
+
+        ActivityPubReturn::answer($res);
+    }
+
+    /**
+     * Generates a list of stalkers for a given profile.
+     *
+     * @param Profile $profile
+     * @param int $since
+     * @param int $limit
+     * @return array of URIs
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function generate_followers($profile, $since, $limit)
+    {
+        /* Fetch Followers */
+        try {
+            $sub = $profile->getSubscribers($since, $limit);
+        } catch (NoResultException $e) {
+            // Just let the exception go on its merry way
+        }
+
+        /* Get followers' URLs */
+        $subs = [];
+        while ($sub->fetch()) {
+            $subs[] = ActivityPubPlugin::actor_uri($sub);
+        }
+
+        return $subs;
+    }
+}

plugins/ActivityPub/actions/apactorfollowing.php

@@ -0,0 +1,133 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * Actor's Following Collection
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class apActorFollowingAction extends ManagedAction
+{
+    protected $needLogin = false;
+    protected $canPost   = true;
+
+    /**
+     * Handle the Following Collection request
+     *
+     * @return void
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    protected function handle()
+    {
+        try {
+            $profile = Profile::getByID($this->trimmed('id'));
+            $profile_id = $profile->getID();
+        } catch (Exception $e) {
+            ActivityPubReturn::error('Invalid Actor URI.', 404);
+        }
+
+        if (!$profile->isLocal()) {
+            ActivityPubReturn::error("This is not a local user.", 403);
+        }
+
+        if (!isset($_GET["page"])) {
+            $page = 0;
+        } else {
+            $page = intval($this->trimmed('page'));
+        }
+
+        if ($page < 0) {
+            ActivityPubReturn::error('Invalid page number.');
+        }
+
+        $since = ($page - 1) * PROFILES_PER_MINILIST;
+        $limit = (($page - 1) == 0 ? 1 : $page) * PROFILES_PER_MINILIST;
+
+        /* Calculate total items */
+        $total_subs  = $profile->subscriptionCount();
+        $total_pages = ceil($total_subs / PROFILES_PER_MINILIST);
+
+        $res = [
+            '@context'     => [
+              "https://www.w3.org/ns/activitystreams",
+              "https://w3id.org/security/v1",
+            ],
+            'id'           => common_local_url('apActorFollowing', ['id' => $profile_id]).(($page != 0) ? '?page='.$page : ''),
+            'type'         => ($page == 0 ? 'OrderedCollection' : 'OrderedCollectionPage'),
+            'totalItems'   => $total_subs
+        ];
+
+        if ($page == 0) {
+            $res['first'] = common_local_url('apActorFollowing', ['id' => $profile_id]).'?page=1';
+        } else {
+            $res['orderedItems'] = $this->generate_following($profile, $since, $limit);
+            $res['partOf'] = common_local_url('apActorFollowing', ['id' => $profile_id]);
+
+            if ($page+1 < $total_pages) {
+                $res['next'] = common_local_url('apActorFollowing', ['id' => $profile_id]).'page='.($page+1 == 1 ? 2 : $page+1);
+            }
+
+            if ($page > 1) {
+                $res['prev'] = common_local_url('apActorFollowing', ['id' => $profile_id]).'?page='.($page-1 <= 0 ? 1 : $page-1);
+            }
+        }
+
+        ActivityPubReturn::answer($res);
+    }
+
+    /**
+     * Generates the list of those a given profile is stalking.
+     *
+     * @param Profile $profile
+     * @param int $since
+     * @param int $limit
+     * @return array of URIs
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function generate_following($profile, $since, $limit)
+    {
+        /* Fetch Following */
+        try {
+            $sub = $profile->getSubscribed($since, $limit);
+        } catch (NoResultException $e) {
+            // Just let the exception go on its merry way
+        }
+
+        /* Get followed' URLs */
+        $subs = [];
+        while ($sub->fetch()) {
+            $subs[] = ActivityPubPlugin::actor_uri($sub);
+        }
+        return $subs;
+    }
+}

plugins/ActivityPub/actions/apactorliked.php

@@ -0,0 +1,153 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * Actor's Liked Collection
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class apActorLikedAction extends ManagedAction
+{
+    protected $needLogin = false;
+    protected $canPost   = true;
+
+    /**
+     * Handle the Liked Collection request
+     *
+     * @return void
+     * @throws EmptyPkeyValueException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    protected function handle()
+    {
+        try {
+            $profile = Profile::getByID($this->trimmed('id'));
+            $profile_id = $profile->getID();
+        } catch (Exception $e) {
+            ActivityPubReturn::error('Invalid Actor URI.', 404);
+        }
+
+        if (!$profile->isLocal()) {
+            ActivityPubReturn::error("This is not a local user.", 403);
+        }
+
+        $limit    = intval($this->trimmed('limit'));
+        $since_id = intval($this->trimmed('since_id'));
+        $max_id   = intval($this->trimmed('max_id'));
+
+        $limit    = empty($limit) ? 40 : $limit;       // Default is 40
+        $since_id = empty($since_id) ? null : $since_id;
+        $max_id   = empty($max_id) ? null : $max_id;
+
+        // Max is 80
+        if ($limit > 80) {
+            $limit = 80;
+        }
+
+        $fave = $this->fetch_faves($profile_id, $limit, $since_id, $max_id);
+
+        $faves = array();
+        while ($fave->fetch()) {
+            $faves[] = $this->pretty_fave(clone ($fave));
+        }
+
+        $res = [
+            '@context'     => [
+              "https://www.w3.org/ns/activitystreams",
+              "https://w3id.org/security/v1",
+            ],
+            'id'           => common_local_url('apActorLiked', ['id' => $profile_id]),
+            'type'         => 'OrderedCollection',
+            'totalItems'   => Fave::countByProfile($profile),
+            'orderedItems' => $faves
+        ];
+
+        ActivityPubReturn::answer($res);
+    }
+
+    /**
+     * Take a fave object and turns it in a pretty array to be used
+     * as a plugin answer
+     *
+     * @param Fave $fave_object
+     * @return array pretty array representating a Fave
+     * @throws EmptyPkeyValueException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    protected function pretty_fave($fave_object)
+    {
+        $res = [
+            'created' => $fave_object->created,
+            'object' => Activitypub_notice::notice_to_array(Notice::getByID($fave_object->notice_id))
+        ];
+
+        return $res;
+    }
+
+    /**
+     * Fetch faves
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param int $user_id
+     * @param int $limit
+     * @param int $since_id
+     * @param int $max_id
+     * @return Fave fetchable fave collection
+     */
+    private static function fetch_faves(
+        $user_id,
+        $limit = 40,
+        $since_id = null,
+        $max_id = null
+        ) {
+        $fav = new Fave();
+
+        $fav->user_id = $user_id;
+
+        $fav->orderBy('modified DESC');
+
+        if ($since_id != null) {
+            $fav->whereAdd("notice_id  > {$since_id}");
+        }
+
+        if ($max_id != null) {
+            $fav->whereAdd("notice_id  < {$max_id}");
+        }
+
+        $fav->limit($limit);
+
+        $fav->find();
+
+        return $fav;
+    }
+}

plugins/ActivityPub/actions/apactoroutbox.php

@@ -0,0 +1,134 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * Inbox Request Handler
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class apActorOutboxAction extends ManagedAction
+{
+    protected $needLogin = false;
+    protected $canPost   = true;
+
+    /**
+     * Handle the Outbox request
+     *
+     * @author Daniel Supernault <danielsupernault@gmail.com>
+     */
+    protected function handle()
+    {
+        try {
+            $profile = Profile::getByID($this->trimmed('id'));
+            $profile_id = $profile->getID();
+        } catch (Exception $e) {
+            ActivityPubReturn::error('Invalid Actor URI.', 404);
+        }
+
+        if (!$profile->isLocal()) {
+            ActivityPubReturn::error("This is not a local user.", 403);
+        }
+
+        if (!isset($_GET["page"])) {
+            $page = 0;
+        } else {
+            $page = intval($this->trimmed('page'));
+        }
+
+        if ($page < 0) {
+            ActivityPubReturn::error('Invalid page number.');
+        }
+
+        $since = ($page - 1) * PROFILES_PER_MINILIST;
+        $limit = (($page - 1) == 0 ? 1 : $page) * PROFILES_PER_MINILIST;
+
+        /* Calculate total items */
+        $total_notes = $profile->noticeCount();
+        $total_pages = ceil($total_notes / PROFILES_PER_MINILIST);
+
+        $res = [
+            '@context'     => [
+              "https://www.w3.org/ns/activitystreams",
+              "https://w3id.org/security/v1",
+            ],
+            'id'           => common_local_url('apActorOutbox', ['id' => $profile_id]).(($page != 0) ? '?page='.$page : ''),
+            'type'         => ($page == 0 ? 'OrderedCollection' : 'OrderedCollectionPage'),
+            'totalItems'   => $total_notes
+        ];
+
+        if ($page == 0) {
+            $res['first'] = common_local_url('apActorOutbox', ['id' => $profile_id]).'?page=1';
+        } else {
+            $res['orderedItems'] = $this->generate_outbox($profile);
+            $res['partOf'] = common_local_url('apActorOutbox', ['id' => $profile_id]);
+
+            if ($page+1 < $total_pages) {
+                $res['next'] = common_local_url('apActorOutbox', ['id' => $profile_id]).'page='.($page+1 == 1 ? 2 : $page+1);
+            }
+
+            if ($page > 1) {
+                $res['prev'] = common_local_url('apActorOutbox', ['id' => $profile_id]).'?page='.($page-1 <= 0 ? 1 : $page-1);
+            }
+        }
+
+        ActivityPubReturn::answer($res);
+    }
+
+    /**
+     * Generates a list of people following given profile.
+     *
+     * @param Profile $profile
+     * @return array of Notices
+     * @throws EmptyPkeyValueException
+     * @throws InvalidUrlException
+     * @throws ServerException
+     * @author Daniel Supernault <danielsupernault@gmail.com>
+     */
+    public function generate_outbox($profile)
+    {
+        /* Fetch Notices */
+        $notices = [];
+        $notice = $profile->getNotices();
+        while ($notice->fetch()) {
+            $note = $notice;
+
+            // TODO: Handle other types
+            if ($note->object_type == 'http://activitystrea.ms/schema/1.0/note') {
+                $notices[] = Activitypub_create::create_to_array(
+                    ActivityPubPlugin::actor_uri($note->getProfile()),
+                    Activitypub_notice::notice_to_array($note)
+                );
+            }
+        }
+
+        return $notices;
+    }
+}

plugins/ActivityPub/actions/apactorprofile.php

@@ -0,0 +1,75 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * Actor's profile (Local users only)
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class apActorProfileAction extends ManagedAction
+{
+    protected $needLogin = false;
+    protected $canPost   = true;
+
+    /**
+     * Handle the Actor Profile request
+     *
+     * @return void
+     * @throws InvalidUrlException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    protected function handle()
+    {
+        if (!empty($id = $this->trimmed('id'))) {
+            try {
+                $profile = Profile::getByID($id);
+            } catch (Exception $e) {
+                ActivityPubReturn::error('Invalid Actor URI.', 404);
+            }
+            unset($id);
+        } else {
+            try {
+                $profile = User::getByNickname($this->trimmed('nickname'))->getProfile();
+            } catch (Exception $e) {
+                ActivityPubReturn::error('Invalid username.', 404);
+            }
+        }
+
+        if (!$profile->isLocal()) {
+            ActivityPubReturn::error("This is not a local user.", 403);
+        }
+
+        $res = Activitypub_profile::profile_to_array($profile);
+
+        ActivityPubReturn::answer($res, 200);
+    }
+}

plugins/ActivityPub/actions/apinbox.php

@@ -0,0 +1,135 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * Inbox Request Handler
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class apInboxAction extends ManagedAction
+{
+    protected $needLogin = false;
+    protected $canPost   = true;
+
+    /**
+     * Handle the Inbox request
+     *
+     * @return void
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    protected function handle()
+    {
+        $path = !empty($this->trimmed('id')) ? common_local_url('apInbox', ['id' => $this->trimmed('id')]) : common_local_url('apInbox');
+        $path = parse_url($path, PHP_URL_PATH);
+
+        if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
+            ActivityPubReturn::error('Only POST requests allowed.');
+        }
+
+        common_debug('ActivityPub Inbox: Received a POST request.');
+        $body = $data = file_get_contents('php://input');
+        common_debug('ActivityPub Inbox: Request contents: '.$data);
+        $data = json_decode(file_get_contents('php://input'), true);
+
+        if (!isset($data['actor'])) {
+            ActivityPubReturn::error('Actor not found in the request.');
+        }
+
+        $actor = Activitypub_explorer::get_profile_from_url($data['actor']);
+        $aprofile = Activitypub_profile::from_profile($actor);
+
+        $actor_public_key = new Activitypub_rsa();
+        $actor_public_key = $actor_public_key->ensure_public_key($actor);
+
+        common_debug('ActivityPub Inbox: HTTP Signature: Validation will now start!');
+
+        $headers = $this->get_all_headers();
+        common_debug('ActivityPub Inbox: Request Headers: '.print_r($headers, true));
+
+        if (!isset($headers['signature'])) {
+            common_debug('ActivityPub Inbox: HTTP Signature: Missing Signature header.');
+            ActivityPubReturn::error('Missing Signature header.', 400);
+        }
+
+        // Extract the signature properties
+        $signatureData = HTTPSignature::parseSignatureHeader($headers['signature']);
+        common_debug('ActivityPub Inbox: HTTP Signature Data: '.print_r($signatureData, true));
+        if (isset($signatureData['error'])) {
+            common_debug('ActivityPub Inbox: HTTP Signature: '.json_encode($signatureData, true));
+            ActivityPubReturn::error(json_encode($signatureData, true), 400);
+        }
+
+        list($verified, $headers) = HTTPSignature::verify($actor_public_key, $signatureData, $headers, $path, $body);
+
+        // If the signature fails verification the first time, update profile as it might have change public key
+        if($verified !== 1) {
+            $res = Activitypub_explorer::get_remote_user_activity($aprofile->getUri());
+            $actor = Activitypub_profile::update_profile($aprofile, $res);
+            $actor_public_key = new Activitypub_rsa();
+            $actor_public_key = $actor_public_key->ensure_public_key($actor);
+            list($verified, $headers) = HTTPSignature::verify($actor_public_key, $signatureData, $headers, $path, $body);
+        }
+
+        // If it still failed despite profile update
+        if($verified !== 1) {
+            common_debug('ActivityPub Inbox: HTTP Signature: Invalid signature.');
+            ActivityPubReturn::error('Invalid signature.');
+        }
+
+        // HTTP signature checked out, make sure the "actor" of the activity matches that of the signature
+        common_debug('ActivityPub Inbox: HTTP Signature: Authorized request. Will now start the inbox handler.');
+
+        try {
+            new Activitypub_inbox_handler($data, $actor);
+            ActivityPubReturn::answer();
+        } catch (Exception $e) {
+            ActivityPubReturn::error($e->getMessage());
+        }
+    }
+
+    /**
+     * Get all HTTP header key/values as an associative array for the current request.
+     *
+     * @return array [string] The HTTP header key/value pairs.
+     * @author PHP Manual Contributed Notes <joyview@gmail.com>
+     */
+    private function get_all_headers()
+    {
+        $headers = [];
+        foreach ($_SERVER as $name => $value) {
+            if (substr($name, 0, 5) == 'HTTP_') {
+                $headers[strtolower(str_replace(' ', '-', ucwords(strtolower(str_replace('_', ' ', substr($name, 5))))))] = $value;
+            }
+        }
+        return $headers;
+    }
+}

plugins/ActivityPub/actions/apnotice.php

@@ -0,0 +1,67 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * Notice (Local notices only)
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class apNoticeAction extends ManagedAction
+{
+    protected $needLogin = false;
+    protected $canPost   = true;
+
+    /**
+     * Handle the Notice request
+     *
+     * @return void
+     * @throws EmptyPkeyValueException
+     * @throws InvalidUrlException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    protected function handle()
+    {
+        try {
+            $notice = Notice::getByID($this->trimmed('id'));
+        } catch (Exception $e) {
+            ActivityPubReturn::error('Invalid Notice URI.', 404);
+        }
+
+        if (!$notice->isLocal()) {
+            ActivityPubReturn::error("This is not a local notice.", 403);
+        }
+
+        $res = Activitypub_notice::notice_to_array($notice);
+
+        ActivityPubReturn::answer($res);
+    }
+}

plugins/ActivityPub/classes/Activitypub_accept.php

@@ -0,0 +1,86 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub error representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_accept extends Managed_DataObject
+{
+    /**
+     * Generates an ActivityPub representation of a Accept
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param array $object
+     * @return array pretty array to be used in a response
+     */
+    public static function accept_to_array($object)
+    {
+        $res = [
+            '@context' => 'https://www.w3.org/ns/activitystreams',
+            'id'     => common_root_url().'accept_follow_from_'.urlencode($object['actor']).'_to_'.urlencode($object['object']),
+            'type'   => 'Accept',
+            'actor'  => $object['object'],
+            'object' => $object
+        ];
+        return $res;
+    }
+
+    /**
+     * Verifies if a given object is acceptable for an Accept Activity.
+     *
+     * @param array $object
+     * @return bool
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function validate_object($object)
+    {
+        if (!is_array($object)) {
+            throw new Exception('Invalid Object Format for Accept Activity.');
+        }
+        if (!isset($object['type'])) {
+            throw new Exception('Object type was not specified for Accept Activity.');
+        }
+        switch ($object['type']) {
+            case 'Follow':
+                // Validate data
+                if (!filter_var($object['object'], FILTER_VALIDATE_URL)) {
+                    throw new Exception("Object is not a valid Object URI for Activity.");
+                }
+                break;
+            default:
+                throw new Exception('This is not a supported Object Type for Accept Activity.');
+        }
+        return true;
+    }
+}

plugins/ActivityPub/classes/Activitypub_announce.php

@@ -0,0 +1,57 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub error representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_announce extends Managed_DataObject
+{
+    /**
+     * Generates an ActivityPub representation of a Announce
+     *
+     * @param $actor
+     * @param array $object
+     * @return array pretty array to be used in a response
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function announce_to_array($actor, $object)
+    {
+        $res = [
+            '@context' => 'https://www.w3.org/ns/activitystreams',
+            "type"   => "Announce",
+            "actor"  => $actor,
+            "object" => $object
+        ];
+        return $res;
+    }
+}

plugins/ActivityPub/classes/Activitypub_attachment.php

@@ -0,0 +1,67 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub Attachment representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_attachment extends Managed_DataObject
+{
+    /**
+     * Generates a pretty array from an Attachment object
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param Attachment $attachment
+     * @return array pretty array to be used in a response
+     */
+    public static function attachment_to_array($attachment)
+    {
+        $res = [
+            '@context' => 'https://www.w3.org/ns/activitystreams',
+            'type'      => 'Document',
+            'mediaType' => $attachment->mimetype,
+            'url'       => $attachment->getUrl(),
+            'size'      => $attachment->getSize(),
+            'name'      => $attachment->getTitle(),
+        ];
+
+        // Image
+        if (substr($res["mediaType"], 0, 5) == "image") {
+            $res["meta"]= [
+                'width'  => $attachment->width,
+                'height' => $attachment->height
+            ];
+        }
+
+        return $res;
+    }
+}

plugins/ActivityPub/classes/Activitypub_create.php

@@ -0,0 +1,85 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub error representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_create extends Managed_DataObject
+{
+    /**
+     * Generates an ActivityPub representation of a Create
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param string $actor
+     * @param array $object
+     * @return array pretty array to be used in a response
+     */
+    public static function create_to_array($actor, $object)
+    {
+        $res = [
+            '@context' => 'https://www.w3.org/ns/activitystreams',
+            'id'     => $object['id'].'/create',
+            'type'   => 'Create',
+            'to'     => $object['to'],
+            'cc'     => $object['cc'],
+            'actor'  => $actor,
+            'object' => $object
+        ];
+        return $res;
+    }
+
+    /**
+     * Verifies if a given object is acceptable for a Create Activity.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param array $object
+     * @throws Exception
+     */
+    public static function validate_object($object)
+    {
+        if (!is_array($object)) {
+            throw new Exception('Invalid Object Format for Create Activity.');
+        }
+        if (!isset($object['type'])) {
+            throw new Exception('Object type was not specified for Create Activity.');
+        }
+        switch ($object['type']) {
+            case 'Note':
+                // Validate data
+                Activitypub_notice::validate_note($object);
+                break;
+            default:
+                throw new Exception('This is not a supported Object Type for Create Activity.');
+        }
+    }
+}

plugins/ActivityPub/classes/Activitypub_delete.php

@@ -0,0 +1,58 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub error representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_delete extends Managed_DataObject
+{
+    /**
+     * Generates an ActivityPub representation of a Delete
+     *
+     * @param $actor
+     * @param array $object
+     * @return array pretty array to be used in a response
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function delete_to_array($actor, $object)
+    {
+        $res = [
+            '@context' => 'https://www.w3.org/ns/activitystreams',
+            'id'     => $object.'/delete',
+            'type'   => 'Delete',
+            'actor'  => $actor,
+            'object' => $object
+        ];
+        return $res;
+    }
+}

plugins/ActivityPub/classes/Activitypub_error.php

@@ -0,0 +1,53 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub error representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_error extends Managed_DataObject
+{
+    /**
+     * Generates a pretty error from a string
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param string $m
+     * @return array pretty array to be used in a response
+     */
+    public static function error_message_to_array($m)
+    {
+        $res = [
+            'error'=> $m
+        ];
+        return $res;
+    }
+}

plugins/ActivityPub/classes/Activitypub_follow.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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub error representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_follow extends Managed_DataObject
+{
+    /**
+     * Generates an ActivityPub representation of a subscription
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param string $actor
+     * @param string $object
+     * @return array pretty array to be used in a response
+     */
+    public static function follow_to_array($actor, $object)
+    {
+        $res = [
+            '@context' => 'https://www.w3.org/ns/activitystreams',
+            'id'     => common_root_url().'follow_from_'.urlencode($actor).'_to_'.urlencode($object),
+            'type'   => 'Follow',
+            'actor'  => $actor,
+            'object' => $object
+       ];
+        return $res;
+    }
+
+    /**
+     * Handles a Follow Activity received by our inbox.
+     *
+     * @param Profile $actor_profile Remote Actor
+     * @param string $object Local Actor
+     * @throws AlreadyFulfilledException
+     * @throws HTTP_Request2_Exception
+     * @throws NoProfileException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function follow($actor_profile, $object)
+    {
+        // Get Actor's Aprofile
+        $actor_aprofile = Activitypub_profile::from_profile($actor_profile);
+
+        // Get Object profile
+        $object_profile = new Activitypub_explorer;
+        $object_profile = $object_profile->lookup($object)[0];
+
+        if (!Subscription::exists($actor_profile, $object_profile)) {
+            Subscription::start($actor_profile, $object_profile);
+            common_debug('ActivityPubPlugin: Accepted Follow request from '.ActivityPubPlugin::actor_uri($actor_profile).' to '.$object);
+        } else {
+            common_debug('ActivityPubPlugin: Received a repeated Follow request from '.ActivityPubPlugin::actor_uri($actor_profile).' to '.$object);
+        }
+
+        // Notify remote instance that we have accepted their request
+        common_debug('ActivityPubPlugin: Notifying remote instance that we have accepted their Follow request request from '.ActivityPubPlugin::actor_uri($actor_profile).' to '.$object);
+        $postman = new Activitypub_postman($actor_profile, [$actor_aprofile]);
+        $postman->accept_follow();
+    }
+}

plugins/ActivityPub/classes/Activitypub_like.php

@@ -0,0 +1,58 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub error representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_like extends Managed_DataObject
+{
+    /**
+     * Generates an ActivityPub representation of a Like
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param string $actor  Actor URI
+     * @param string $object Notice URI
+     * @return array pretty array to be used in a response
+     */
+    public static function like_to_array($actor, $object)
+    {
+        $res = [
+            '@context' => 'https://www.w3.org/ns/activitystreams',
+            'id'     => common_root_url().'like_from_'.urlencode($actor).'_to_'.urlencode($object),
+            "type"   => "Like",
+            "actor"  => $actor,
+            "object" => $object
+        ];
+        return $res;
+    }
+}

plugins/ActivityPub/classes/Activitypub_mention_tag.php

@@ -0,0 +1,57 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub Mention Tag representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_mention_tag extends Managed_DataObject
+{
+    /**
+     * Generates an ActivityPub representation of a Mention Tag
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param string $href Actor Uri
+     * @param array $name Mention name
+     * @return array pretty array to be used in a response
+     */
+    public static function mention_tag_to_array_from_values($href, $name)
+    {
+        $res = [
+            '@context' => 'https://www.w3.org/ns/activitystreams',
+            "type" => "Mention",
+            "href" => $href,
+            "name" => $name
+         ];
+        return $res;
+    }
+}

plugins/ActivityPub/classes/Activitypub_notice.php

@@ -0,0 +1,252 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub notice representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_notice extends Managed_DataObject
+{
+    /**
+     * Generates a pretty notice from a Notice object
+     *
+     * @param Notice $notice
+     * @return array array to be used in a response
+     * @throws EmptyPkeyValueException
+     * @throws InvalidUrlException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function notice_to_array($notice)
+    {
+        $profile = $notice->getProfile();
+        $attachments = [];
+        foreach ($notice->attachments() as $attachment) {
+            $attachments[] = Activitypub_attachment::attachment_to_array($attachment);
+        }
+
+        $tags = [];
+        foreach ($notice->getTags() as $tag) {
+            if ($tag != "") {       // Hacky workaround to avoid stupid outputs
+                $tags[] = Activitypub_tag::tag_to_array($tag);
+            }
+        }
+
+        $cc = [common_local_url('apActorFollowers', ['id' => $profile->getID()])];
+        foreach ($notice->getAttentionProfiles() as $to_profile) {
+            $cc[]  = $href = $to_profile->getUri();
+            $tags[] = Activitypub_mention_tag::mention_tag_to_array_from_values($href, $to_profile->getNickname().'@'.parse_url($href, PHP_URL_HOST));
+        }
+
+        // In a world without walls and fences, we should make everything Public!
+        $to[]= 'https://www.w3.org/ns/activitystreams#Public';
+
+        $item = [
+            '@context' => 'https://www.w3.org/ns/activitystreams',
+            'id'           => common_local_url('apNotice', ['id' => $notice->getID()]),
+            'type'         => 'Note',
+            'published'    => str_replace(' ', 'T', $notice->getCreated()).'Z',
+            'url'          => $notice->getUrl(),
+            'attributedTo' => ActivityPubPlugin::actor_uri($profile),
+            'to'           => ['https://www.w3.org/ns/activitystreams#Public'],
+            'cc'           => $cc,
+            'atomUri'      => $notice->getUrl(),
+            'conversation' => $notice->getConversationUrl(),
+            'content'      => $notice->getRendered(),
+            'isLocal'      => $notice->isLocal(),
+            'attachment'   => $attachments,
+            'tag'          => $tags
+        ];
+
+        // Is this a reply?
+        if (!empty($notice->reply_to)) {
+            $item['inReplyTo'] = common_local_url('apNotice', ['id' => $notice->getID()]);
+            $item['inReplyToAtomUri'] = Notice::getById($notice->reply_to)->getUrl();
+        }
+
+        // Do we have a location for this notice?
+        try {
+            $location = Notice_location::locFromStored($notice);
+            $item['latitude']  = $location->lat;
+            $item['longitude'] = $location->lon;
+        } catch (Exception $e) {
+            // Apparently no.
+        }
+
+        return $item;
+    }
+
+    /**
+     * Create a Notice via ActivityPub Note Object.
+     * Returns created Notice.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param array $object
+     * @param Profile|null $actor_profile
+     * @return Notice
+     * @throws Exception
+     */
+    public static function create_notice($object, $actor_profile = null)
+    {
+        $id      = $object['id'];         // int
+        $url     = $object['url'];        // string
+        $content = $object['content'];    // string
+
+        // possible keys: ['inReplyTo', 'latitude', 'longitude']
+        $settings = [];
+        if (isset($object['inReplyTo'])) {
+            $settings['inReplyTo'] = $object['inReplyTo'];
+        }
+        if (isset($object['latitude'])) {
+            $settings['latitude']  = $object['latitude'];
+        }
+        if (isset($object['longitude'])) {
+            $settings['longitude'] = $object['longitude'];
+        }
+
+        // Ensure Actor Profile
+        if (is_null($actor_profile)) {
+            $actor_profile = ActivityPub_explorer::get_profile_from_url($object['actor']);
+        }
+
+        $act = new Activity();
+        $act->verb = ActivityVerb::POST;
+        $act->time = time();
+        $act->actor = $actor_profile->asActivityObject();
+        $act->context = new ActivityContext();
+        $options = ['source' => 'ActivityPub', 'uri' => $id, 'url' => $url];
+
+        // Is this a reply?
+        if (isset($settings['inReplyTo'])) {
+            try {
+                $inReplyTo = ActivityPubPlugin::grab_notice_from_url($settings['inReplyTo']);
+                $act->context->replyToID  = $inReplyTo->getUri();
+                $act->context->replyToUrl = $inReplyTo->getUrl();
+            } catch (Exception $e) {
+                // It failed to grab, maybe we got this note from another source
+                // (e.g.: OStatus) that handles this differently or we really
+                // failed to get it...
+                // Welp, nothing that we can do about, let's
+                // just fake we don't have such notice.
+            }
+        } else {
+            $inReplyTo = null;
+        }
+
+        // Mentions
+        $mentions = [];
+        if (isset($object['tag']) && is_array($object['tag'])) {
+            foreach ($object['tag'] as $tag) {
+                if ($tag['type'] == 'Mention') {
+                    $mentions[] = $tag['href'];
+                }
+            }
+        }
+        $mentions_profiles = [];
+        $discovery = new Activitypub_explorer;
+        foreach ($mentions as $mention) {
+            try {
+                $mentions_profiles[] = $discovery->lookup($mention)[0];
+            } catch (Exception $e) {
+                // Invalid actor found, just let it go. // TODO: Fallback to OStatus
+            }
+        }
+        unset($discovery);
+
+        foreach ($mentions_profiles as $mp) {
+            $act->context->attention[ActivityPubPlugin::actor_uri($mp)] = 'http://activitystrea.ms/schema/1.0/person';
+        }
+
+        // Add location if that is set
+        if (isset($settings['latitude'], $settings['longitude'])) {
+            $act->context->location = Location::fromLatLon($settings['latitude'], $settings['longitude']);
+        }
+
+        /* Reject notice if it is too long (without the HTML)
+        if (Notice::contentTooLong($content)) {
+            throw new Exception('That\'s too long. Maximum notice size is %d character.');
+        }*/
+
+        $actobj = new ActivityObject();
+        $actobj->type = ActivityObject::NOTE;
+        $actobj->content = strip_tags($content, '<p><b><i><u><a><ul><ol><li>');
+
+        // Finally add the activity object to our activity
+        $act->objects[] = $actobj;
+
+        $note = Notice::saveActivity($act, $actor_profile, $options);
+
+        return $note;
+    }
+
+    /**
+     * Validates a note.
+     *
+     * @param array $object
+     * @return bool
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function validate_note($object)
+    {
+        if (!isset($object['attributedTo'])) {
+            common_debug('ActivityPub Notice Validator: Rejected because attributedTo was not specified.');
+            throw new Exception('No attributedTo specified.');
+        }
+        if (!isset($object['id'])) {
+            common_debug('ActivityPub Notice Validator: Rejected because Object ID was not specified.');
+            throw new Exception('Object ID not specified.');
+        } elseif (!filter_var($object['id'], FILTER_VALIDATE_URL)) {
+            common_debug('ActivityPub Notice Validator: Rejected because Object ID is invalid.');
+            throw new Exception('Invalid Object ID.');
+        }
+        if (!isset($object['type']) || $object['type'] !== 'Note') {
+            common_debug('ActivityPub Notice Validator: Rejected because of Type.');
+            throw new Exception('Invalid Object type.');
+        }
+        if (!isset($object['content'])) {
+            common_debug('ActivityPub Notice Validator: Rejected because Content was not specified.');
+            throw new Exception('Object content was not specified.');
+        }
+        if (!isset($object['url'])) {
+            throw new Exception('Object URL was not specified.');
+        } elseif (!filter_var($object['url'], FILTER_VALIDATE_URL)) {
+            common_debug('ActivityPub Notice Validator: Rejected because Object URL is invalid.');
+            throw new Exception('Invalid Object URL.');
+        }
+        if (!isset($object['cc'])) {
+            common_debug('ActivityPub Notice Validator: Rejected because Object CC was not specified.');
+            throw new Exception('Object CC was not specified.');
+        }
+        return true;
+    }
+}

plugins/ActivityPub/classes/Activitypub_pending_follow_requests.php

@@ -0,0 +1,109 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub's Pending follow requests
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_pending_follow_requests extends Managed_DataObject
+{
+    public $__table = 'activitypub_pending_follow_requests';
+    public $local_profile_id;
+    public $remote_profile_id;
+    private $_reldb = null;
+
+    /**
+     * Return table definition for Schema setup and DB_DataObject usage.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @return array array of column definitions
+     */
+    public static function schemaDef()
+    {
+        return [
+            'fields' => [
+                'local_profile_id'  => ['type' => 'integer', 'not null' => true],
+                'remote_profile_id' => ['type' => 'integer', 'not null' => true],
+                'relation_id'       => ['type' => 'serial',  'not null' => true],
+            ],
+            'primary key' => ['relation_id'],
+            'foreign keys' => [
+                'activitypub_pending_follow_requests_local_profile_id_fkey'  => ['profile', ['local_profile_id' => 'id']],
+                'activitypub_pending_follow_requests_remote_profile_id_fkey' => ['profile', ['remote_profile_id' => 'id']],
+            ],
+        ];
+    }
+
+    public function __construct($actor, $remote_actor)
+    {
+        $this->local_profile_id  = $actor;
+        $this->remote_profile_id = $remote_actor;
+    }
+
+    /**
+     * Add Follow request to table.
+     *
+     * @return boolean true if added, false otherwise
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function add()
+    {
+        return !$this->exists() && $this->insert();
+    }
+
+    /**
+     * Check if a Follow request is pending.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @return boolean true if is pending, false otherwise
+     */
+    public function exists()
+    {
+        $this->_reldb = clone($this);
+        if ($this->_reldb->find() > 0) {
+            $this->_reldb->fetch();
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Remove a request from the pending table.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @return boolean true if removed, false otherwise
+     */
+    public function remove()
+    {
+        return $this->exists() && $this->_reldb->delete();
+    }
+}

plugins/ActivityPub/classes/Activitypub_profile.php

@@ -0,0 +1,476 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub Profile
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_profile extends Managed_DataObject
+{
+    public $__table = 'activitypub_profile';
+    public $uri;                             // text()   not_null
+    public $profile_id;                      // int(4)  primary_key not_null
+    public $inboxuri;                        // text()   not_null
+    public $sharedInboxuri;                  // text()
+    public $nickname;                        // varchar(64)  multiple_key not_null
+    public $fullname;                        // text()
+    public $profileurl;                      // text()
+    public $homepage;                        // text()
+    public $bio;                             // text()  multiple_key
+    public $location;                        // text()
+    public $created;                         // datetime()   not_null default_CURRENT_TIMESTAMP
+    public $modified;                        // datetime()   not_null default_CURRENT_TIMESTAMP
+
+    /**
+     * Return table definition for Schema setup and DB_DataObject usage.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @return array array of column definitions
+     */
+    public static function schemaDef()
+    {
+        return [
+            'fields' => [
+                'uri' => ['type' => 'text', 'not null' => true],
+                'profile_id' => ['type' => 'integer'],
+                'inboxuri' => ['type' => 'text', 'not null' => true],
+                'sharedInboxuri' => ['type' => 'text'],
+                'created' => ['type' => 'datetime', 'not null' => true, 'default' => 'CURRENT_TIMESTAMP', 'description' => 'date this record was created'],
+                'modified' => ['type' => 'datetime', 'not null' => true, 'default' => 'CURRENT_TIMESTAMP', 'description' => 'date this record was modified'],
+            ],
+            'primary key' => ['profile_id'],
+            'foreign keys' => [
+                'activitypub_profile_profile_id_fkey' => ['profile', ['profile_id' => 'id']],
+            ],
+        ];
+    }
+
+    /**
+     * Generates a pretty profile from a Profile object
+     *
+     * @param Profile $profile
+     * @return array array to be used in a response
+     * @throws InvalidUrlException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function profile_to_array($profile)
+    {
+        $uri = ActivityPubPlugin::actor_uri($profile);
+        $id = $profile->getID();
+        $rsa = new Activitypub_rsa();
+        $public_key = $rsa->ensure_public_key($profile);
+        unset($rsa);
+        $res = [
+            '@context'          => [
+                'https://www.w3.org/ns/activitystreams',
+                'https://w3id.org/security/v1',
+                [
+                    'manuallyApprovesFollowers' => 'as:manuallyApprovesFollowers'
+                ]
+            ],
+            'id'                => $uri,
+            'type'              => 'Person',
+            'following'         => common_local_url('apActorFollowing', ['id' => $id]),
+            'followers'         => common_local_url('apActorFollowers', ['id' => $id]),
+            'liked'             => common_local_url('apActorLiked', ['id' => $id]),
+            'inbox'             => common_local_url('apInbox', ['id' => $id]),
+            'outbox'            => common_local_url('apActorOutbox', ['id' => $id]),
+            'preferredUsername' => $profile->getNickname(),
+            'name'              => $profile->getBestName(),
+            'summary'           => ($desc = $profile->getDescription()) == null ? "" : $desc,
+            'url'               => $profile->getUrl(),
+            'manuallyApprovesFollowers' => false,
+            'publicKey' => [
+                'id'    => $uri."#public-key",
+                'owner' => $uri,
+                'publicKeyPem' => $public_key
+            ],
+            'tag' => [],
+            'attachment' => [],
+            'icon' => [
+                'type'      => 'Image',
+                'mediaType' => 'image/png',
+                'height'    => AVATAR_PROFILE_SIZE,
+                'width'     => AVATAR_PROFILE_SIZE,
+                'url'       => $profile->avatarUrl(AVATAR_PROFILE_SIZE)
+            ]
+        ];
+
+        if ($profile->isLocal()) {
+            $res['endpoints']['sharedInbox'] = common_local_url('apInbox');
+        } else {
+            $aprofile = new Activitypub_profile();
+            $aprofile = $aprofile->from_profile($profile);
+            $res['endpoints']['sharedInbox'] = $aprofile->sharedInboxuri;
+        }
+
+        return $res;
+    }
+
+    /**
+     * Insert the current object variables into the database
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @access public
+     * @throws ServerException
+     */
+    public function do_insert()
+    {
+        $profile = new Profile();
+
+        $profile->created = $this->created = $this->modified = common_sql_now();
+
+        $fields = [
+                    'uri'      => 'profileurl',
+                    'nickname' => 'nickname',
+                    'fullname' => 'fullname',
+                    'bio'      => 'bio'
+                    ];
+
+        foreach ($fields as $af => $pf) {
+            $profile->$pf = $this->$af;
+        }
+
+        $this->profile_id = $profile->insert();
+        if ($this->profile_id === false) {
+            $profile->query('ROLLBACK');
+            throw new ServerException('Profile insertion failed.');
+        }
+
+        $ok = $this->insert();
+
+        if ($ok === false) {
+            $profile->query('ROLLBACK');
+            $this->query('ROLLBACK');
+            throw new ServerException('Cannot save ActivityPub profile.');
+        }
+    }
+
+    /**
+     * Fetch the locally stored profile for this Activitypub_profile
+     *
+     * @return Profile
+     * @throws NoProfileException if it was not found
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function local_profile()
+    {
+        $profile = Profile::getKV('id', $this->profile_id);
+        if (!$profile instanceof Profile) {
+            throw new NoProfileException($this->profile_id);
+        }
+        return $profile;
+    }
+
+    /**
+     * Generates an Activitypub_profile from a Profile
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param Profile $profile
+     * @return Activitypub_profile
+     * @throws Exception if no Activitypub_profile exists for given Profile
+     */
+    public static function from_profile(Profile $profile)
+    {
+        $profile_id = $profile->getID();
+
+        $aprofile = self::getKV('profile_id', $profile_id);
+        if (!$aprofile instanceof Activitypub_profile) {
+            // No Activitypub_profile for this profile_id,
+            if (!$profile->isLocal()) {
+                // create one!
+                $aprofile = self::create_from_local_profile($profile);
+            } else {
+                throw new Exception('No Activitypub_profile for Profile ID: '.$profile_id. ', this is a local user.');
+            }
+        }
+
+        $fields = [
+                    'uri'      => 'profileurl',
+                    'nickname' => 'nickname',
+                    'fullname' => 'fullname',
+                    'bio'      => 'bio'
+                    ];
+
+        foreach ($fields as $af => $pf) {
+            $aprofile->$af = $profile->$pf;
+        }
+
+        return $aprofile;
+    }
+
+    /**
+     * Given an existent local profile creates an ActivityPub profile.
+     * One must be careful not to give a user profile to this function
+     * as only remote users have ActivityPub_profiles on local instance
+     *
+     * @param Profile $profile
+     * @return Activitypub_profile
+     * @throws HTTP_Request2_Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private static function create_from_local_profile(Profile $profile)
+    {
+        $aprofile = new Activitypub_profile();
+
+        $url = $profile->getUri();
+        $inboxes = Activitypub_explorer::get_actor_inboxes_uri($url);
+
+        if ($inboxes == null) {
+            throw new Exception('This is not an ActivityPub user thus AProfile is politely refusing to proceed.');
+        }
+
+        $aprofile->created = $aprofile->modified = common_sql_now();
+
+        $aprofile                 = new Activitypub_profile;
+        $aprofile->profile_id     = $profile->getID();
+        $aprofile->uri            = $url;
+        $aprofile->nickname       = $profile->getNickname();
+        $aprofile->fullname       = $profile->getFullname();
+        $aprofile->bio            = substr($profile->getDescription(), 0, 1000);
+        $aprofile->inboxuri       = $inboxes["inbox"];
+        $aprofile->sharedInboxuri = $inboxes["sharedInbox"];
+
+        $aprofile->insert();
+
+        return $aprofile;
+    }
+
+    /**
+     * Returns sharedInbox if possible, inbox otherwise
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @return string Inbox URL
+     */
+    public function get_inbox()
+    {
+        if (is_null($this->sharedInboxuri)) {
+            return $this->inboxuri;
+        }
+
+        return $this->sharedInboxuri;
+    }
+
+    /**
+     * Getter for uri property
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @return string URI
+     */
+    public function getUri()
+    {
+        return $this->uri;
+    }
+
+    /**
+     * Getter for url property
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @return string URL
+     */
+    public function getUrl()
+    {
+        return $this->getUri();
+    }
+
+    /**
+     * Getter for id property
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @return int
+     */
+    public function getID()
+    {
+        return $this->profile_id;
+    }
+
+    /**
+     * Ensures a valid Activitypub_profile when provided with a valid URI.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param string $url
+     * @return Activitypub_profile
+     * @throws Exception if it isn't possible to return an Activitypub_profile
+     */
+    public static function fromUri($url)
+    {
+        try {
+            return self::from_profile(Activitypub_explorer::get_profile_from_url($url));
+        } catch (Exception $e) {
+            throw new Exception('No valid ActivityPub profile found for given URI.');
+        }
+    }
+
+    /**
+     * Look up, and if necessary create, an Activitypub_profile for the remote
+     * entity with the given webfinger address.
+     * This should never return null -- you will either get an object or
+     * an exception will be thrown.
+     *
+     * @author GNU social
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param string $addr webfinger address
+     * @return Activitypub_profile
+     * @throws Exception on error conditions
+     */
+    public static function ensure_web_finger($addr)
+    {
+        // Normalize $addr, i.e. add 'acct:' if missing
+        $addr = Discovery::normalize($addr);
+
+        // Try the cache
+        $uri = self::cacheGet(sprintf('activitypub_profile:webfinger:%s', $addr));
+
+        if ($uri !== false) {
+            if (is_null($uri)) {
+                // Negative cache entry
+                // TRANS: Exception.
+                throw new Exception(_m('Not a valid webfinger address (via cache).'));
+            }
+            try {
+                return self::fromUri($uri);
+            } catch (Exception $e) {
+                common_log(LOG_ERR, sprintf(__METHOD__ . ': Webfinger address cache inconsistent with database, did not find Activitypub_profile uri==%s', $uri));
+                self::cacheSet(sprintf('activitypub_profile:webfinger:%s', $addr), false);
+            }
+        }
+
+        // Now, try some discovery
+
+        $disco = new Discovery();
+
+        try {
+            $xrd = $disco->lookup($addr);
+        } catch (Exception $e) {
+            // Save negative cache entry so we don't waste time looking it up again.
+            // @todo FIXME: Distinguish temporary failures?
+            self::cacheSet(sprintf('activitypub_profile:webfinger:%s', $addr), null);
+            // TRANS: Exception.
+            throw new Exception(_m('Not a valid webfinger address.'));
+        }
+
+        $hints = array_merge(
+            array('webfinger' => $addr),
+            DiscoveryHints::fromXRD($xrd)
+                );
+
+        // If there's an Hcard, let's grab its info
+        if (array_key_exists('hcard', $hints)) {
+            if (!array_key_exists('profileurl', $hints) ||
+                        $hints['hcard'] != $hints['profileurl']) {
+                $hcardHints = DiscoveryHints::fromHcardUrl($hints['hcard']);
+                $hints = array_merge($hcardHints, $hints);
+            }
+        }
+
+        // If we got a profile page, try that!
+        $profileUrl = null;
+        if (array_key_exists('profileurl', $hints)) {
+            $profileUrl = $hints['profileurl'];
+            try {
+                common_log(LOG_INFO, "Discovery on acct:$addr with profile URL $profileUrl");
+                $aprofile = self::fromUri($hints['profileurl']);
+                self::cacheSet(sprintf('activitypub_profile:webfinger:%s', $addr), $aprofile->getUri());
+                return $aprofile;
+            } catch (Exception $e) {
+                common_log(LOG_WARNING, "Failed creating profile from profile URL '$profileUrl': " . $e->getMessage());
+                // keep looking
+                                //
+                                // @todo FIXME: This means an error discovering from profile page
+                                // may give us a corrupt entry using the webfinger URI, which
+                                // will obscure the correct page-keyed profile later on.
+            }
+        }
+
+        // XXX: try hcard
+        // XXX: try FOAF
+
+        // TRANS: Exception. %s is a webfinger address.
+        throw new Exception(sprintf(_m('Could not find a valid profile for "%s".'), $addr));
+    }
+
+    /**
+     * Update remote user profile in local instance
+     * Depends on do_update
+     *
+     * @param Activitypub_profile $aprofile
+     * @param array $res remote response
+     * @return Profile remote Profile object
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function update_profile($aprofile, $res)
+    {
+        // ActivityPub Profile
+        $aprofile->uri            = $res['id'];
+        $aprofile->nickname       = $res['preferredUsername'];
+        $aprofile->fullname       = isset($res['name']) ? $res['name'] : null;
+        $aprofile->bio            = isset($res['summary']) ? substr(strip_tags($res['summary']), 0, 1000) : null;
+        $aprofile->inboxuri       = $res['inbox'];
+        $aprofile->sharedInboxuri = isset($res['endpoints']['sharedInbox']) ? $res['endpoints']['sharedInbox'] : $res['inbox'];
+
+        $profile = $aprofile->local_profile();
+
+        $profile->modified = $aprofile->modified = common_sql_now();
+
+        $fields = [
+                    'uri'      => 'profileurl',
+                    'nickname' => 'nickname',
+                    'fullname' => 'fullname',
+                    'bio'      => 'bio'
+                    ];
+
+        foreach ($fields as $af => $pf) {
+            $profile->$pf = $aprofile->$af;
+        }
+
+        // Profile
+        $profile->update();
+        $aprofile->update();
+
+        // Public Key
+        Activitypub_rsa::update_public_key($profile, $res['publicKey']['publicKeyPem']);
+
+        // Avatar
+        if (isset($res['icon']['url'])) {
+            try {
+                Activitypub_explorer::update_avatar($profile, $res['icon']['url']);
+            } catch (Exception $e) {
+                // Let the exception go, it isn't a serious issue
+                common_debug('An error ocurred while grabbing remote avatar'.$e->getMessage());
+            }
+        }
+
+        return $profile;
+    }
+}

plugins/ActivityPub/classes/Activitypub_reject.php

@@ -0,0 +1,55 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub error representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_reject extends Managed_DataObject
+{
+    /**
+     * Generates an ActivityPub representation of a Reject
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param array $object
+     * @return array pretty array to be used in a response
+     */
+    public static function reject_to_array($object)
+    {
+        $res = [
+                '@context' => 'https://www.w3.org/ns/activitystreams',
+                'type'     => 'Reject',
+                'object'   => $object
+        ];
+        return $res;
+    }
+}

plugins/ActivityPub/classes/Activitypub_rsa.php

@@ -0,0 +1,179 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub Keys System
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_rsa extends Managed_DataObject
+{
+    public $__table = 'activitypub_rsa';
+    public $profile_id;                      // int(4)  primary_key not_null
+    public $private_key;                     // text()   not_null
+    public $public_key;                      // text()   not_null
+    public $created;                         // datetime()   not_null default_CURRENT_TIMESTAMP
+    public $modified;                        // datetime()   not_null default_CURRENT_TIMESTAMP
+
+    /**
+     * Return table definition for Schema setup and DB_DataObject usage.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @return array array of column definitions
+     */
+    public static function schemaDef()
+    {
+        return [
+                'fields' => [
+                    'profile_id'  => ['type' => 'integer'],
+                    'private_key' => ['type' => 'text'],
+                    'public_key'  => ['type' => 'text', 'not null' => true],
+                    'created' => ['type' => 'datetime', 'not null' => true, 'default' => 'CURRENT_TIMESTAMP', 'description' => 'date this record was created'],
+                    'modified' => ['type' => 'datetime', 'not null' => true, 'default' => 'CURRENT_TIMESTAMP', 'description' => 'date this record was modified'],
+                ],
+                'primary key' => ['profile_id'],
+                'foreign keys' => [
+                    'activitypub_profile_profile_id_fkey' => ['profile', ['profile_id' => 'id']],
+                ],
+        ];
+    }
+
+    public function get_private_key($profile)
+    {
+        $this->profile_id = $profile->getID();
+        $apRSA = self::getKV('profile_id', $this->profile_id);
+        if (!$apRSA instanceof Activitypub_rsa) {
+            // No existing key pair for this profile
+            if ($profile->isLocal()) {
+                self::generate_keys($this->private_key, $this->public_key);
+                $this->store_keys();
+            } else {
+                throw new Exception('This is a remote Profile, there is no Private Key for this Profile.');
+            }
+        }
+        return $apRSA->private_key;
+    }
+
+    /**
+     * Guarantees a Public Key for a given profile.
+     *
+     * @param Profile $profile
+     * @param bool $fetch
+     * @return string The public key
+     * @throws ServerException It should never occur, but if so, we break everything!
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function ensure_public_key($profile, $fetch = true)
+    {
+        $this->profile_id = $profile->getID();
+        $apRSA = self::getKV('profile_id', $this->profile_id);
+        if (!$apRSA instanceof Activitypub_rsa) {
+            // No existing key pair for this profile
+            if ($profile->isLocal()) {
+                self::generate_keys($this->private_key, $this->public_key);
+                $this->store_keys();
+            } else {
+                // This should never happen, but try to recover!
+                if ($fetch) {
+                    $res = Activitypub_explorer::get_remote_user_activity(ActivityPubPlugin::actor_uri($profile));
+                    Activitypub_rsa::update_public_key($profile, $res['publicKey']['publicKeyPem']);
+                    return self::ensure_public_key($profile, false);
+                } else {
+                    throw new ServerException('Activitypub_rsa: Failed to find keys for given profile. That should have not happened!');
+                }
+            }
+        }
+        return $apRSA->public_key;
+    }
+
+    /**
+     * Insert the current object variables into the database.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @access public
+     * @throws ServerException
+     */
+    public function store_keys()
+    {
+        $this->created = $this->modified = common_sql_now();
+        $ok = $this->insert();
+        if ($ok === false) {
+            throw new ServerException('Cannot save ActivityPub RSA.');
+        }
+    }
+
+    /**
+     * Generates a pair of RSA keys.
+     *
+     * @author PHP Manual Contributed Notes <dirt@awoms.com>
+     * @param string $private_key in/out
+     * @param string $public_key in/out
+     */
+    public static function generate_keys(&$private_key, &$public_key)
+    {
+        $config = [
+            'digest_alg'       => 'sha512',
+            'private_key_bits' => 2048,
+            'private_key_type' => OPENSSL_KEYTYPE_RSA,
+        ];
+
+        // Create the private and public key
+        $res = openssl_pkey_new($config);
+
+        // Extract the private key from $res to $private_key
+        openssl_pkey_export($res, $private_key);
+
+        // Extract the public key from $res to $pubKey
+        $pubKey = openssl_pkey_get_details($res);
+        $public_key = $pubKey["key"];
+        unset($pubKey);
+    }
+
+    /**
+     * Update public key.
+     *
+     * @param Profile $profile
+     * @param string $public_key
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function update_public_key($profile, $public_key)
+    {
+        // Public Key
+        $apRSA = new Activitypub_rsa();
+        $apRSA->profile_id = $profile->getID();
+        $apRSA->public_key = $public_key;
+        $apRSA->modified = common_sql_now();
+        if (!$apRSA->update()) {
+            $apRSA->insert();
+        }
+    }
+}

plugins/ActivityPub/classes/Activitypub_tag.php

@@ -0,0 +1,55 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub representation of a Tag
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_tag extends Managed_DataObject
+{
+    /**
+     * Generates a pretty tag from a Tag object
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param array Tag $tag
+     * @return array pretty array to be used in a response
+     */
+    public static function tag_to_array($tag)
+    {
+        $res = [
+            '@context' => 'https://www.w3.org/ns/activitystreams',
+            'name' => $tag,
+            'url'  => common_local_url('tag', ['tag' => $tag])
+        ];
+        return $res;
+    }
+}

plugins/ActivityPub/classes/Activitypub_undo.php

@@ -0,0 +1,87 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub error representation
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_undo extends Managed_DataObject
+{
+    /**
+     * Generates an ActivityPub representation of a Undo
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param array $object
+     * @return array pretty array to be used in a response
+     */
+    public static function undo_to_array($object)
+    {
+        $res = [
+            '@context' => 'https://www.w3.org/ns/activitystreams',
+            'id'     => $object['id'].'/undo',
+            'type'   => 'Undo',
+            'actor'  => $object['actor'],
+            'object' => $object
+        ];
+        return $res;
+    }
+
+    /**
+     * Verifies if a given object is acceptable for a Undo Activity.
+     *
+     * @param array $object
+     * @return bool
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function validate_object($object)
+    {
+        if (!is_array($object)) {
+            throw new Exception('Invalid Object Format for Undo Activity.');
+        }
+        if (!isset($object['type'])) {
+            throw new Exception('Object type was not specified for Undo Activity.');
+        }
+        switch ($object['type']) {
+            case 'Follow':
+            case 'Like':
+                // Validate data
+                if (!filter_var($object['object'], FILTER_VALIDATE_URL)) {
+                    throw new Exception('Object is not a valid Object URI for Activity.');
+                }
+                break;
+            default:
+                throw new Exception('This is not a supported Object Type for Undo Activity.');
+        }
+        return true;
+    }
+}

plugins/ActivityPub/doc/index.html

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <title>ActivityPub plugin for GNU Social API Documentation</title>
+    <!-- needed for adaptive design -->
+    <meta charset="utf-8"/>
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <link href="https://fonts.googleapis.com/css?family=Montserrat:300,400,700|Roboto:300,400,700" rel="stylesheet">
+    <link rel="icon" href="https://git.gnu.io/gnu/gnu-social/raw/b286e8798b7f89cd72ef19dc335624100f43ce94/theme/neo-gnu/favicon.ico">
+    <!--
+    ReDoc doesn't change outer page styles
+    -->
+    <style>
+      body {
+        margin: 0;
+        padding: 0;
+      }
+    </style>
+  </head>
+  <body>
+    <redoc spec-url='openapi.json'></redoc>
+    <script src="https://cdn.jsdelivr.net/npm/redoc@next/bundles/redoc.standalone.js"> </script>
+  </body>
+</html>

plugins/ActivityPub/doc/objects_and_activities.md

@@ -0,0 +1,101 @@
+ActivityPub Plugin for GNU Social Doc
+=====================================
+
+## Contents
+
+- [Objects](#entities)
+    - [Attachment](#attachment)
+    - [Error](#error)
+    - [Image](#image)
+    - [Notice](#notice)
+    - [Profile](#profile)
+    - [Tag](#tag)
+- [Activities](#activities)
+    - [Create](#create)
+    - [Announce](#announce)
+    - [Delete](#delete)
+    - [Undo](#undo)
+    - [Accept](#accept)
+    - [Reject](#reject)
+    - [Like](#like)
+    - [Follow](#follow)
+
+## Objects
+
+### Attachment
+
+| Attribute                | Description                                     | Nullable | Type    |
+| ------------------------ | ----------------------------------------------- | -------- | ------- |
+| `id`                     | ID of the attachment                            | no       | int32   |
+| `mimetype`               | Mimetype                                        | no       | string  |
+| `url`                    | URL of the locally hosted version of the image  | no       | string  |
+| `meta`                   | See **attachment metadata** below               | yes      | Array   |
+| `title`                  | Attachment title                                | no       | string  |
+
+**Attachment metadata:**
+
+Images may contain `width`, `height`, `size`.
+
+### Error
+
+The most important part of an error response is the HTTP status code. Standard semantics are followed. The body of an error is a JSON object with this structure:
+
+| Attribute                | Description                         | Nullable | Type    |
+| ------------------------ | ----------------------------------- | -------- | ------- |
+| `error`                  | A textual description of the error  | no       | string  |
+
+### Image
+
+| Attribute                | Description     | Nullable | Type    |
+| ------------------------ | --------------- | -------- | ------- |
+| `type`                   | "Image"         | no       | string  |
+| `width`                  | Image's width   | no       | int32   |
+| `height`                 | Image's height  | no       | int32   |
+| `url`                    | Image URL       | no       | string  |
+
+### Notice
+
+| Attribute                | Description                                       | Nullable | Type                                 |
+| ------------------------ | ------------------------------------------------- | -------- | ------------------------------------ |
+| `id`                     | Notice's URL                                      | no       | string                               |
+| `type`                   | Notice's Type                                     | no       | string                               |
+| `actor`                  | URL of Notice owner profile page (can be remote)  | no       | string                               |
+| `published`              | DateTime of notice creation                       | no       | datetime                             |
+| `to`                     | To                                                | no       | string                               |
+| `cc`                     | CC                                                | no       | string                               |
+| `content`                | Notice's Content in plain text                    | no       | string                               |
+| `url`                    | Notice's URL                                      | no       | string                               |
+| `reply_to`               | ID of the notice this replies                     | yes      | int32                                |
+| `is_local`               | Boolean, true if local, false otherwise           | no       | bool                                 |
+| `conversation`           | Notice conversation id                            | no       | int32                                |
+| `attachment`             | Array of [Attachments](#attachment)               | no       | Array of [Attachments](#attachment)  |
+| `tag`                    | Array of [Tags](#tag)                             | no       | Array of [Tags](#tag)                |
+
+### Profile
+
+| Attribute                | Description                                      | Nullable | Type             |
+| ------------------------ | ------------------------------------------------ | -------- | ---------------- |
+| `@context`               | Standard compliance                              | no       | string           |
+| `id`                     | Actor's id                                       | no       | int32            |
+| `type`                   | "Person"                                         | no       | string           |
+| `nickname`               | Actor's nickname                                 | no       | string           |
+| `is_local`               | True if local, false otherwise                   | no       | bool             |
+| `inbox`                  | URL to Actor's inbox endpoint                    | no       | string           |
+| `outbox`                 | URL to Actor's outbox endpoint                   | no       | string           |
+| `display_name`           | The Actor's display name                         | no       | string           |
+| `followers`              | URL to Actor's followers endpoint                | no       | string           |
+| `followers_count`        | Total number of followers                        | no       | int32            |
+| `following`              | URL to Actor's following endpoint                | no       | string           |
+| `following_count`        | Total number of following                        | no       | int32            |
+| `liked`                  | URL to Actor's Liked collection endpoint         | no       | string           |
+| `liked_count`            | Total number of favorites                        | no       | int32            |
+| `summary`                | Actor's biography                                | no       | string           |
+| `url`                    | URL of the Actor's profile page (can be remote)  | no       | string           |
+| `avatar`                 | Actor's avatar                                   | no       | [Image](#image)  |
+
+### Tag
+
+| Attribute                | Description                                  | Nullable | Type       |
+| ------------------------ | -------------------------------------------- | -------- | ---------- |
+| `name`                   | The hashtag, not including the preceding `#` | no       | string     |
+| `url`                    | The URL of the hashtag                       | no       | string     |

plugins/ActivityPub/doc/openapi.json

@@ -0,0 +1,673 @@
+{
+    "openapi": "3.0.0",
+    "info": {
+        "description": "## Retrieving objects\nThe HTTP GET method may be dereferenced against an object's `id` property to retrieve the activity.\nThe plugin supports HTTP content negotiation as defined in [RFC7231](https://tools.ietf.org/html/rfc7231) in every endpoint suffixed with .json .\nThe plugin always presents ActivityStreams object representation in response to every request.\nThe client MUST specify an `Accept` header with the `application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\"` media type in order to retrieve the activity.\n\n## Selecting ranges\n\nFor most `GET` operations that return arrays, the query parameters `max_id` and `since_id` can be used to specify the range of IDs to return.\nAPI methods that return collections of items can return a `Link` header containing URLs for the `next` and `prev` pages.\nSee the [Link header RFC](https://tools.ietf.org/html/rfc5988) for more information.\n\n## Pretty output\n\nFor most operations if the `pretty` parameter is set a formated output will be generated (useful for learning about the API or debuging purposes).\n\n## Errors\n\nIf the request you make doesn't go through, the plugin will usually respond with an [Error](#error).\n\n___\n\n> **Note:** Some attributes in the payload can have ``null`` value and are marked as _nullable_ on the tables below. Attributes that are not nullable are guaranteed to return a valid value.",
+        "version": "1.0.0",
+        "title": "ActivityPub plugin for GNU Social",
+        "contact": {
+            "email": "diogo@fc.up.pt"
+        },
+        "license": {
+            "name": "AGPLv3",
+            "url": "https://git.gnu.io/gnu/GS-ActivityPub-plugin/blob/COPYING"
+        }
+    },
+    "externalDocs": {
+        "description": "For a complete definition of the objects and activities available click here.",
+        "url": "https://git.gnu.io/gnu/GS-ActivityPub-plugin/doc/objects_and_activities.md"
+    },
+    "paths": {
+        "/{nickname}": {
+            "get": {
+                "summary": "Fetching an Actor's profile",
+                "description": "Returns a Profile.",
+                "responses": {
+                    "200": {
+                        "description": "Returns a Profile",
+                        "content": {
+                            "application/json": {
+                                "schema": {
+                                    "type": "array",
+                                    "items": {
+                                        "$ref": "#/components/schemas/Profile"
+                                    }
+                                }
+                            }
+                        }
+                    }
+                },
+                "parameters": [
+                    {
+                        "name": "Content-Type",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/json"
+                        }
+                    },
+                    {
+                        "name": "Accept",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/activity+json"
+                        }
+                    }
+                ]
+            }
+        },
+        "/{nickname}/inbox.json": {
+            "post": {
+                "summary": "Actor Inbox endpoint",
+                "description": "Allows the publish of activities with attention to a given Actor",
+                "parameters": [
+                    {
+                        "name": "Content-Type",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/json"
+                        }
+                    },
+                    {
+                        "name": "Accept",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/activity+json"
+                        }
+                    }
+                ],
+                "responses": {
+                    "200": {
+                        "description": "Returns the same activity it received"
+                    }
+                }
+            }
+        },
+        "/{nickname}/liked.json": {
+            "get": {
+                "summary": "Liked Collection",
+                "description": "Getting an Actor's Liked Collection",
+                "parameters": [
+                    {
+                        "name": "Content-Type",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/json"
+                        }
+                    },
+                    {
+                        "name": "Accept",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/activity+json"
+                        }
+                    },
+                    {
+                        "name": "max_id",
+                        "in": "query",
+                        "required": false,
+                        "schema": {
+                            "type": "integer",
+                            "format": "int32"
+                        },
+                        "description": "Get a list of likes with ID less than this value",
+                        "format": "int32"
+                    },
+                    {
+                        "name": "since_id",
+                        "in": "query",
+                        "required": false,
+                        "schema": {
+                            "type": "integer",
+                            "format": "int32"
+                        },
+                        "description": "Get a list of likes with ID greater than this value"
+                    },
+                    {
+                        "name": "limit",
+                        "in": "query",
+                        "required": false,
+                        "schema": {
+                            "type": "integer",
+                            "format": "int32",
+                            "default": "40"
+                        },
+                        "description": "Maximum number of likes to get (Max 80)"
+                    }
+                ],
+                "responses": {
+                    "200": {
+                        "description": "Returns Actor's Liked Collection",
+                        "content": {
+                            "application/json": {
+                                "schema": {
+                                    "type": "array",
+                                    "items": {
+                                        "$ref": "#/components/schemas/Liked Collection"
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        },
+        "/{nickname}/followers.json": {
+            "get": {
+                "summary": "Followers Collection",
+                "description": "Getting an Actor's Followers Collection",
+                "parameters": [
+                    {
+                        "name": "Content-Type",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/json"
+                        }
+                    },
+                    {
+                        "name": "Accept",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/activity+json"
+                        }
+                    },
+                    {
+                        "name": "page",
+                        "in": "query",
+                        "required": false,
+                        "schema": {
+                            "type": "integer",
+                            "format": "int32",
+                            "default": "1"
+                        },
+                        "description": "Page index (starts in 1)"
+                    }
+                ],
+                "responses": {
+                    "200": {
+                        "description": "Returns Actor's Followers Collection",
+                        "content": {
+                            "application/json": {
+                                "schema": {
+                                    "type": "array",
+                                    "items": {
+                                        "$ref": "#/components/schemas/Follow Collection"
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        },
+        "/{nickname}/following.json": {
+            "get": {
+                "summary": "Following Collection",
+                "description": "Getting an Actor's Following Collection",
+                "parameters": [
+                    {
+                        "name": "Content-Type",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/json"
+                        }
+                    },
+                    {
+                        "name": "Accept",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/activity+json"
+                        }
+                    },
+                    {
+                        "name": "page",
+                        "in": "query",
+                        "required": false,
+                        "schema": {
+                            "type": "integer",
+                            "format": "int32",
+                            "default": "1"
+                        },
+                        "description": "Page index (starts in 1)"
+                    }
+                ],
+                "responses": {
+                    "200": {
+                        "description": "Returns Actor's Following Collection",
+                        "content": {
+                            "application/json": {
+                                "schema": {
+                                    "type": "array",
+                                    "items": {
+                                        "$ref": "#/components/schemas/Follow Collection"
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        },
+        "/inbox.json": {
+            "post": {
+                "summary": "SharedInbox endpoint",
+                "description": "Allows the publish of activities",
+                "parameters": [
+                    {
+                        "name": "Content-Type",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/json"
+                        }
+                    },
+                    {
+                        "name": "Accept",
+                        "in": "header",
+                        "required": true,
+                        "schema": {
+                            "type": "string",
+                            "default": "application/activity+json"
+                        }
+                    }
+                ],
+                "responses": {
+                    "200": {
+                        "description": "Returns the same activity it received"
+                    }
+                }
+            }
+        }
+    },
+    "components": {
+        "schemas": {
+            "Note": {
+                "type": "object",
+                "required": [
+                    "@context",
+                    "id",
+                    "type",
+                    "actor",
+                    "published",
+                    "to",
+                    "cc",
+                    "content",
+                    "url",
+                    "reply_to",
+                    "is_local",
+                    "conversation",
+                    "attachment",
+                    "tag"
+                ],
+                "properties": {
+                    "@context": {
+                        "type": "string",
+                        "value": "https://www.w3.org/ns/activitystreams",
+                        "default": "https://www.w3.org/ns/activitystreams"
+                    },
+                    "id": {
+                        "description": "Notice's URI",
+                        "type": "string"
+                    },
+                    "type": {
+                        "description": "Notice's Type",
+                        "type": "string"
+                    },
+                    "actor": {
+                        "description": "URL of Notice owner profile page (can be remote)",
+                        "type": "string"
+                    },
+                    "published": {
+                        "description": "DateTime of notice creation",
+                        "type": "string",
+                        "format": "date-time"
+                    },
+                    "to": {
+                        "description": "To",
+                        "type": "string"
+                    },
+                    "cc": {
+                        "description": "CC",
+                        "type": "string"
+                    },
+                    "content": {
+                        "description": "Notice's Content in plain text",
+                        "type": "string"
+                    },
+                    "url": {
+                        "description": "Notice's URL",
+                        "type": "string"
+                    },
+                    "reply_to": {
+                        "description": "ID of the notice this replies",
+                        "type": "string"
+                    },
+                    "is_local": {
+                        "description": "true if local, false otherwise",
+                        "type": "string"
+                    },
+                    "conversation": {
+                        "description": "Notice conversation id",
+                        "type": "integer",
+                        "format": "int32"
+                    },
+                    "attachment": {
+                        "description": "Array of Attachments",
+                        "type": "Array of Attachments"
+                    },
+                    "tag": {
+                        "description": "Array of Tags",
+                        "type": "Array of Tags"
+                    }
+                },
+                "xml": {
+                    "name": "Note"
+                }
+            },
+            "Image": {
+                "type": "object",
+                "required": [
+                    "@context",
+                    "type",
+                    "width",
+                    "height",
+                    "url"
+                ],
+                "properties": {
+                    "@context": {
+                        "type": "string",
+                        "value": "https://www.w3.org/ns/activitystreams",
+                        "default": "https://www.w3.org/ns/activitystreams"
+                    },
+                    "type": {
+                        "description": "Image",
+                        "type": "string"
+                    },
+                    "width": {
+                        "description": "Image's width",
+                        "type": "integer",
+                        "format": "int32"
+                    },
+                    "height": {
+                        "description": "Image's height",
+                        "type": "integer",
+                        "format": "int32"
+                    },
+                    "url": {
+                        "description": "Image URL",
+                        "type": "string"
+                    }
+                },
+                "xml": {
+                    "name": "Image"
+                }
+            },
+            "Attachment": {
+                "type": "object",
+                "required": [
+                    "@context",
+                    "id",
+                    "mimetype",
+                    "url",
+                    "title"
+                ],
+                "properties": {
+                    "@context": {
+                        "type": "string",
+                        "value": "https://www.w3.org/ns/activitystreams",
+                        "default": "https://www.w3.org/ns/activitystreams"
+                    },
+                    "id": {
+                        "type": "integer",
+                        "format": "int32",
+                        "description": "Id of the Attachment"
+                    },
+                    "mimetype": {
+                        "type": "string",
+                        "description": "Mimetype"
+                    },
+                    "url": {
+                        "type": "string",
+                        "description": "URL of locally hosted version of the attachment"
+                    },
+                    "meta": {
+                        "type": "array",
+                        "description": "Attachment metadata:\n\nImages may contain *width*, *height*, *size*.",
+                        "items": {}
+                    },
+                    "title": {
+                        "type": "string",
+                        "description": "Attachment title"
+                    }
+                },
+                "xml": {
+                    "name": "Attachment"
+                }
+            },
+            "Profile": {
+                "type": "object",
+                "required": [
+                    "@context",
+                    "id",
+                    "nickname",
+                    "is_local",
+                    "inbox",
+                    "outbox",
+                    "display_name",
+                    "followers",
+                    "followers_count",
+                    "following",
+                    "following_count",
+                    "liked",
+                    "liked_count",
+                    "summary",
+                    "url",
+                    "avatar"
+                ],
+                "properties": {
+                    "@context": {
+                        "type": "string",
+                        "value": "https://www.w3.org/ns/activitystreams",
+                        "default": "https://www.w3.org/ns/activitystreams"
+                    },
+                    "id": {
+                        "type": "string",
+                        "description": "Local URI"
+                    },
+                    "type": "Person",
+                    "nickname": {
+                        "type": "string",
+                        "description": "Actor's nickname"
+                    },
+                    "is_local": {
+                        "type": "boolean",
+                        "description": "True if local, false otherwise"
+                    },
+                    "inbox": {
+                        "type": "string",
+                        "description": "URL to Actor's inbox endpoint"
+                    },
+                    "sharedInbox": {
+                        "type": "string",
+                        "description": "URL to Actor's sharedInbox endpoint"
+                    },
+                    "outbox": {
+                        "type": "string",
+                        "description": "URL to Actor's outbox endpoint"
+                    },
+                    "display_name": {
+                        "type": "string",
+                        "description": "The Actor's display name"
+                    },
+                    "followers": {
+                        "type": "string",
+                        "description": "URL to Actor's followers collection"
+                    },
+                    "followers_count": {
+                        "type": "integer",
+                        "format": "int32",
+                        "description": "Total number of followers"
+                    },
+                    "following": {
+                        "type": "string",
+                        "description": "URL to Actor's following collection"
+                    },
+                    "following_count": {
+                        "type": "integer",
+                        "format": "int32",
+                        "description": "Total number of following"
+                    },
+                    "liked": {
+                        "type": "string",
+                        "description": "URL to Actor's Liked collection"
+                    },
+                    "liked_count": {
+                        "type": "integer",
+                        "format": "int32",
+                        "description": "Total number of favorites"
+                    },
+                    "summary": {
+                        "type": "string",
+                        "description": "Actor's biography"
+                    },
+                    "url": {
+                        "type": "string",
+                        "description": "URL of the Actor's profile page (can be remote)"
+                    },
+                    "avatar": {
+                        "type": "Image",
+                        "description": "Actor's avatar"
+                    }
+                },
+                "xml": {
+                    "name": "Profile"
+                }
+            },
+            "Tag": {
+                "type": "object",
+                "required": [
+                    "@context",
+                    "name",
+                    "url"
+                ],
+                "properties": {
+                    "@context": {
+                        "type": "string",
+                        "value": "https://www.w3.org/ns/activitystreams",
+                        "default": "https://www.w3.org/ns/activitystreams"
+                    },
+                    "name": {
+                        "type": "string",
+                        "description": "The hashtag, not including the preceding #"
+                    },
+                    "url": {
+                        "type": "string",
+                        "description": "The URL of the hashtag"
+                    }
+                },
+                "xml": {
+                    "name": "Tag"
+                }
+            },
+            "Liked Collection": {
+                "type": "object",
+                "required": [
+                    "@context",
+                    "id",
+                    "type",
+                    "totalItems",
+                    "orderedItems"
+                ],
+                "properties": {
+                    "@context": {
+                        "type": "string",
+                        "value": "https://www.w3.org/ns/activitystreams",
+                        "default": "https://www.w3.org/ns/activitystreams"
+                    },
+                    "id": {
+                        "type": "string",
+                        "description": "URL for current endpoint"
+                    },
+                    "type": {
+                        "type": "string",
+                        "description": "OrderedCollection"
+                    },
+                    "totalItems": {
+                        "type": "integer",
+                        "format": "int32",
+                        "description": "Total number of favorites"
+                    },
+                    "orderedItems": {
+                        "type": "Array of Notices",
+                        "description": "Array of Notices"
+                    }
+                }
+            },
+            "Follow Collection": {
+                "type": "object",
+                "required": [
+                    "@context",
+                    "id",
+                    "type",
+                    "totalItems",
+                    "orderedItems"
+                ],
+                "properties": {
+                    "@context": {
+                        "type": "string",
+                        "value": "https://www.w3.org/ns/activitystreams",
+                        "default": "https://www.w3.org/ns/activitystreams"
+                    },
+                    "id": {
+                        "type": "string",
+                        "description": "URL for current endpoint"
+                    },
+                    "type": {
+                        "type": "string",
+                        "description": "OrderedCollection"
+                    },
+                    "totalItems": {
+                        "type": "integer",
+                        "format": "int32",
+                        "description": "Total number of items"
+                    },
+                    "prev": {
+                        "type": "string",
+                        "description": "Previous page URL"
+                    },
+                    "next": {
+                        "type": "string",
+                        "description": "Next page URL"
+                    },
+                    "orderedItems": {
+                        "type": "Array of string",
+                        "description": "The URL of each profile"
+                    }
+                }
+            }
+        },
+        "links": {},
+        "callbacks": {}
+    },
+    "security": [],
+    "servers": []
+}

plugins/ActivityPub/lib/AcceptHeader.php

@@ -0,0 +1,116 @@
+<?php
+/**
+ * Note : Code is released under the GNU LGPL
+ *
+ * Please do not change the header of this file
+ *
+ * This library is free software; you can redistribute it and/or modify it under the terms of the GNU
+ * Lesser General Public License as published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This library 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 Lesser General Public License for more details.
+ */
+
+/**
+ * The AcceptHeader page will parse and sort the different
+ * allowed types for the content negociations
+ *
+ * @author Pierrick Charron <pierrick@webstart.fr>
+ */
+class AcceptHeader extends \ArrayObject
+{
+    /**
+     * Constructor
+     *
+     * @param string $header Value of the Accept header
+     * @return void
+     */
+    public function __construct($header)
+    {
+        $acceptedTypes = $this->_parse($header);
+        usort($acceptedTypes, [$this, '_compare']);
+        parent::__construct($acceptedTypes);
+    }
+
+    /**
+     * Parse the accept header and return an array containing
+     * all the informations about the Accepted types
+     *
+     * @param string $data Value of the Accept header
+     * @return array
+     */
+    private function _parse($data)
+    {
+        $array = [];
+        $items = explode(',', $data);
+        foreach ($items as $item) {
+            $elems = explode(';', $item);
+
+            $acceptElement = [];
+            $mime = current($elems);
+            list($type, $subtype) = explode('/', $mime);
+            $acceptElement['type'] = trim($type);
+            $acceptElement['subtype'] = trim($subtype);
+            $acceptElement['raw'] = $mime;
+
+            $acceptElement['params'] = [];
+            while (next($elems)) {
+                list($name, $value) = explode('=', current($elems));
+                $acceptElement['params'][trim($name)] = trim($value);
+            }
+
+            $array[] = $acceptElement;
+        }
+        return $array;
+    }
+
+    /**
+     * Compare two Accepted types with their parameters to know
+     * if one media type should be used instead of an other
+     *
+     * @param array $a The first media type and its parameters
+     * @param array $b The second media type and its parameters
+     * @return int
+     */
+    private function _compare($a, $b)
+    {
+        $a_q = isset($a['params']['q']) ? floatval($a['params']['q']) : 1.0;
+        $b_q = isset($b['params']['q']) ? floatval($b['params']['q']) : 1.0;
+        if ($a_q === $b_q) {
+            $a_count = count($a['params']);
+            $b_count = count($b['params']);
+            if ($a_count === $b_count) {
+                if ($r = $this->_compareSubType($a['subtype'], $b['subtype'])) {
+                    return $r;
+                } else {
+                    return $this->_compareSubType($a['type'], $b['type']);
+                }
+            } else {
+                return $a_count < $b_count;
+            }
+        } else {
+            return $a_q < $b_q;
+        }
+    }
+
+    /**
+     * Compare two subtypes
+     *
+     * @param string $a First subtype to compare
+     * @param string $b Second subtype to compare
+     * @return int
+     */
+    private function _compareSubType($a, $b)
+    {
+        if ($a === '*' && $b !== '*') {
+            return 1;
+        } elseif ($b === '*' && $a !== '*') {
+            return -1;
+        } else {
+            return 0;
+        }
+    }
+}

plugins/ActivityPub/lib/Activitypub_activityverb2.php

@@ -0,0 +1,98 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * Utility class to hold a bunch of constant defining default verb types
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_activityverb2 extends Managed_DataObject
+{
+    const FULL_LIST =
+    [
+        'Accept'          => 'https://www.w3.org/ns/activitystreams#Accept',
+        'TentativeAccept' => 'https://www.w3.org/ns/activitystreams#TentativeAccept',
+        'Add'             => 'https://www.w3.org/ns/activitystreams#Add',
+        'Arrive'          => 'https://www.w3.org/ns/activitystreams#Arrive',
+        'Create'          => 'https://www.w3.org/ns/activitystreams#Create',
+        'Delete'          => 'https://www.w3.org/ns/activitystreams#Delete',
+        'Follow'          => 'https://www.w3.org/ns/activitystreams#Follow',
+        'Ignore'          => 'https://www.w3.org/ns/activitystreams#Ignore',
+        'Join'            => 'https://www.w3.org/ns/activitystreams#Join',
+        'Leave'           => 'https://www.w3.org/ns/activitystreams#Leave',
+        'Like'            => 'https://www.w3.org/ns/activitystreams#Like',
+        'Offer'           => 'https://www.w3.org/ns/activitystreams#Offer',
+        'Invite'          => 'https://www.w3.org/ns/activitystreams#Invite',
+        'Reject'          => 'https://www.w3.org/ns/activitystreams#Reject',
+        'TentativeReject' => 'https://www.w3.org/ns/activitystreams#TentativeReject',
+        'Remove'          => 'https://www.w3.org/ns/activitystreams#Remove',
+        'Undo'            => 'https://www.w3.org/ns/activitystreams#Undo',
+        'Update'          => 'https://www.w3.org/ns/activitystreams#Update',
+        'View'            => 'https://www.w3.org/ns/activitystreams#View',
+        'Listen'          => 'https://www.w3.org/ns/activitystreams#Listen',
+        'Read'            => 'https://www.w3.org/ns/activitystreams#Read',
+        'Move'            => 'https://www.w3.org/ns/activitystreams#Move',
+        'Travel'          => 'https://www.w3.org/ns/activitystreams#Travel',
+        'Announce'        => 'https://www.w3.org/ns/activitystreams#Announce',
+        'Block'           => 'https://www.w3.org/ns/activitystreams#Block',
+        'Flag'            => 'https://www.w3.org/ns/activitystreams#Flag',
+        'Dislike'         => 'https://www.w3.org/ns/activitystreams#Dislike',
+        'Question'        => 'https://www.w3.org/ns/activitystreams#Question'
+    ];
+
+    const KNOWN =
+    [
+        'Accept',
+        'Create',
+        'Delete',
+        'Follow',
+        'Like',
+        'Undo',
+        'Announce'
+    ];
+
+    /**
+     * Converts canonical into verb.
+     *
+     * @author GNU social
+     * @param string $verb
+     * @return string
+     */
+    public static function canonical($verb)
+    {
+        $ns = 'https://www.w3.org/ns/activitystreams#';
+        if (substr($verb, 0, mb_strlen($ns)) == $ns) {
+            return substr($verb, mb_strlen($ns));
+        } else {
+            return $verb;
+        }
+    }
+}

plugins/ActivityPub/lib/discoveryhints.php

@@ -0,0 +1,158 @@
+<?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    Evan Prodromou
+ * @author    Brion Vibber
+ * @author    James Walker
+ * @author    Siebrand Mazeland
+ * @author    Mikael Nordfeldth
+ * @author    Diogo Cordeiro
+ * @copyright 2010-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+class DiscoveryHints
+{
+    public static function fromXRD(XML_XRD $xrd)
+    {
+        $hints = [];
+
+        if (Event::handle('StartDiscoveryHintsFromXRD', [$xrd, &$hints])) {
+            foreach ($xrd->links as $link) {
+                switch ($link->rel) {
+                case WebFingerResource_Profile::PROFILEPAGE:
+                    $hints['profileurl'] = $link->href;
+                    break;
+                case Discovery::UPDATESFROM:
+                    if (empty($link->type) || $link->type == 'application/atom+xml') {
+                        $hints['feedurl'] = $link->href;
+                    }
+                    break;
+                case Discovery::HCARD:
+                case Discovery::MF2_HCARD:
+                    $hints['hcard'] = $link->href;
+                    break;
+                default:
+                    break;
+                }
+            }
+            Event::handle('EndDiscoveryHintsFromXRD', [$xrd, &$hints]);
+        }
+
+        return $hints;
+    }
+
+    public static function fromHcardUrl($url)
+    {
+        $client = new HTTPClient();
+        $client->setHeader('Accept', 'text/html,application/xhtml+xml');
+        try {
+            $response = $client->get($url);
+
+            if (!$response->isOk()) {
+                return null;
+            }
+        } catch (HTTP_Request2_Exception $e) {
+            // Any HTTPClient error that might've been thrown
+            common_log(LOG_ERR, __METHOD__ . ':'.$e->getMessage());
+            return null;
+        }
+
+        return self::hcardHints(
+            $response->getBody(),
+            $response->getEffectiveUrl()
+        );
+    }
+
+    public static function hcardHints($body, $url)
+    {
+        $hcard = self::_hcard($body, $url);
+
+        if (empty($hcard)) {
+            return [];
+        }
+
+        $hints = [];
+
+        // XXX: don't copy stuff into an array and then copy it again
+
+        if (array_key_exists('nickname', $hcard) && !empty($hcard['nickname'][0])) {
+            $hints['nickname'] = $hcard['nickname'][0];
+        }
+
+        if (array_key_exists('name', $hcard) && !empty($hcard['name'][0])) {
+            $hints['fullname'] = $hcard['name'][0];
+        }
+
+        if (array_key_exists('photo', $hcard) && count($hcard['photo'])) {
+            $hints['avatar'] = $hcard['photo'][0];
+        }
+
+        if (array_key_exists('note', $hcard) && !empty($hcard['note'][0])) {
+            $hints['bio'] = $hcard['note'][0];
+        }
+
+        if (array_key_exists('adr', $hcard) && !empty($hcard['adr'][0])) {
+            $hints['location'] = $hcard['adr'][0]['value'];
+        }
+
+        if (array_key_exists('url', $hcard) && !empty($hcard['url'][0])) {
+            $hints['homepage'] = $hcard['url'][0];
+        }
+
+        return $hints;
+    }
+
+    public static function _hcard($body, $url)
+    {
+        $mf2 = new Mf2\Parser($body, $url);
+        $mf2 = $mf2->parse();
+
+        if (empty($mf2['items'])) {
+            return null;
+        }
+
+        $hcards = [];
+
+        foreach ($mf2['items'] as $item) {
+            if (!in_array('h-card', $item['type'])) {
+                continue;
+            }
+
+            // We found a match, return it immediately
+            if (isset($item['properties']['url']) && in_array($url, $item['properties']['url'])) {
+                return $item['properties'];
+            }
+
+            // Let's keep all the hcards for later, to return one of them at least
+            $hcards[] = $item['properties'];
+        }
+
+        // No match immediately for the url we expected, but there were h-cards found
+        if (count($hcards) > 0) {
+            return $hcards[0];
+        }
+
+        return null;
+    }
+}

plugins/ActivityPub/lib/explorer.php

@@ -0,0 +1,482 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub's own Explorer
+ *
+ * Allows to discovery new (or the same) Profiles (both local or remote)
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_explorer
+{
+    private $discovered_actor_profiles = [];
+
+    /**
+     * Shortcut function to get a single profile from its URL.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param string $url
+     * @return Profile
+     * @throws Exception
+     */
+    public static function get_profile_from_url($url)
+    {
+        $discovery = new Activitypub_explorer;
+        // Get valid Actor object
+        $actor_profile = $discovery->lookup($url);
+        if (!empty($actor_profile)) {
+            return $actor_profile[0];
+        }
+        throw new Exception('Invalid Actor.');
+    }
+
+    /**
+     * Get every profile from the given URL
+     * This function cleans the $this->discovered_actor_profiles array
+     * so that there is no erroneous data
+     *
+     * @param string $url User's url
+     * @return array of Profile objects
+     * @throws HTTP_Request2_Exception
+     * @throws NoProfileException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function lookup($url)
+    {
+        if (in_array($url, ACTIVITYPUB_PUBLIC_TO)) {
+            return [];
+        }
+
+        common_debug('ActivityPub Explorer: Started now looking for '.$url);
+        $this->discovered_actor_profiles = [];
+
+        return $this->_lookup($url);
+    }
+
+    /**
+     * Get every profile from the given URL
+     * This is a recursive function that will accumulate the results on
+     * $discovered_actor_profiles array
+     *
+     * @param string $url User's url
+     * @return array of Profile objects
+     * @throws HTTP_Request2_Exception
+     * @throws NoProfileException
+     * @throws ServerException
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function _lookup($url)
+    {
+        // First check if we already have it locally and, if so, return it
+        // If the local fetch fails: grab it remotely, store locally and return
+        if (! ($this->grab_local_user($url) || $this->grab_remote_user($url))) {
+            throw new Exception('User not found.');
+        }
+
+        return $this->discovered_actor_profiles;
+    }
+
+    /**
+     * This ensures that we are using a valid ActivityPub URI
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param string $url
+     * @return boolean success state (related to the response)
+     * @throws Exception (If the HTTP request fails)
+     */
+    private function ensure_proper_remote_uri($url)
+    {
+        $client    = new HTTPClient();
+        $headers   = [];
+        $headers[] = 'Accept: application/ld+json; profile="https://www.w3.org/ns/activitystreams"';
+        $headers[] = 'User-Agent: GNUSocialBot v0.1 - https://gnu.io/social';
+        $response  = $client->get($url, $headers);
+        $res = json_decode($response->getBody(), true);
+        if (self::validate_remote_response($res)) {
+            $this->temp_res = $res;
+            return true;
+        } else {
+            common_debug('ActivityPub Explorer: Invalid potential remote actor while ensuring URI: '.$url. '. He returned the following: '.json_encode($res, JSON_UNESCAPED_SLASHES));
+        }
+
+        return false;
+    }
+
+    /**
+     * Get a local user profile from its URL and joins it on
+     * $this->discovered_actor_profiles
+     *
+     * @param string $uri Actor's uri
+     * @param bool $online
+     * @return boolean success state
+     * @throws NoProfileException
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function grab_local_user($uri, $online = false)
+    {
+        if ($online) {
+            common_debug('ActivityPub Explorer: Searching locally for '.$uri. ' with online resources.');
+        } else {
+            common_debug('ActivityPub Explorer: Searching locally for '.$uri. ' offline.');
+        }
+        // Ensure proper remote URI
+        // If an exception occurs here it's better to just leave everything
+        // break than to continue processing
+        if ($online && $this->ensure_proper_remote_uri($uri)) {
+            $uri = $this->temp_res["id"];
+        }
+
+        // Try standard ActivityPub route
+        // Is this a known filthy little mudblood?
+        $aprofile = self::get_aprofile_by_url($uri);
+        if ($aprofile instanceof Activitypub_profile) {
+            $profile = $aprofile->local_profile();
+            common_debug('ActivityPub Explorer: Found a local Aprofile for '.$uri);
+            // We found something!
+            $this->discovered_actor_profiles[]= $profile;
+            unset($this->temp_res); // IMPORTANT to avoid _dangerous_ noise in the Explorer system
+            return true;
+        } else {
+            common_debug('ActivityPub Explorer: Unable to find a local Aprofile for '.$uri.' - looking for a Profile instead.');
+            // Well, maybe it is a pure blood?
+            // Iff, we are in the same instance:
+            $ACTIVITYPUB_BASE_ACTOR_URI_length = strlen(ACTIVITYPUB_BASE_ACTOR_URI);
+            if (substr($uri, 0, $ACTIVITYPUB_BASE_ACTOR_URI_length) == ACTIVITYPUB_BASE_ACTOR_URI) {
+                try {
+                    $profile = Profile::getByID(intval(substr($uri, $ACTIVITYPUB_BASE_ACTOR_URI_length)));
+                    common_debug('ActivityPub Explorer: Found a Profile for '.$uri);
+                    // We found something!
+                    $this->discovered_actor_profiles[]= $profile;
+                    unset($this->temp_res); // IMPORTANT to avoid _dangerous_ noise in the Explorer system
+                    return true;
+                } catch (Exception $e) {
+                    // Let the exception go on its merry way.
+                    common_debug('ActivityPub Explorer: Unable to find a Profile for '.$uri);
+                }
+            }
+        }
+
+        // If offline grabbing failed, attempt again with online resources
+        if (!$online) {
+            common_debug('ActivityPub Explorer: Will try everything again with online resources against: '.$uri);
+            return $this->grab_local_user($uri, true);
+        }
+
+        return false;
+    }
+
+    /**
+     * Get a remote user(s) profile(s) from its URL and joins it on
+     * $this->discovered_actor_profiles
+     *
+     * @param string $url User's url
+     * @return boolean success state
+     * @throws HTTP_Request2_Exception
+     * @throws NoProfileException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function grab_remote_user($url)
+    {
+        common_debug('ActivityPub Explorer: Trying to grab a remote actor for '.$url);
+        if (!isset($this->temp_res)) {
+            $client    = new HTTPClient();
+            $headers   = [];
+            $headers[] = 'Accept: application/ld+json; profile="https://www.w3.org/ns/activitystreams"';
+            $headers[] = 'User-Agent: GNUSocialBot v0.1 - https://gnu.io/social';
+            $response  = $client->get($url, $headers);
+            $res = json_decode($response->getBody(), true);
+        } else {
+            $res = $this->temp_res;
+            unset($this->temp_res);
+        }
+        if (isset($res['type']) && $res['type'] === 'OrderedCollection' && isset($res['first'])) { // It's a potential collection of actors!!!
+            common_debug('ActivityPub Explorer: Found a collection of actors for '.$url);
+            $this->travel_collection($res['first']);
+            return true;
+        } elseif (self::validate_remote_response($res)) {
+            common_debug('ActivityPub Explorer: Found a valid remote actor for '.$url);
+            $this->discovered_actor_profiles[]= $this->store_profile($res);
+            return true;
+        } else {
+            common_debug('ActivityPub Explorer: Invalid potential remote actor while grabbing remotely: '.$url. '. He returned the following: '.json_encode($res, JSON_UNESCAPED_SLASHES));
+        }
+
+        // TODO: Fallback to OStatus
+        return false;
+    }
+
+    /**
+     * Save remote user profile in local instance
+     *
+     * @param array $res remote response
+     * @return Profile remote Profile object
+     * @throws NoProfileException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function store_profile($res)
+    {
+        // ActivityPub Profile
+        $aprofile                 = new Activitypub_profile;
+        $aprofile->uri            = $res['id'];
+        $aprofile->nickname       = $res['preferredUsername'];
+        $aprofile->fullname       = isset($res['name']) ? $res['name'] : null;
+        $aprofile->bio            = isset($res['summary']) ? substr(strip_tags($res['summary']), 0, 1000) : null;
+        $aprofile->inboxuri       = $res['inbox'];
+        $aprofile->sharedInboxuri = isset($res['endpoints']['sharedInbox']) ? $res['endpoints']['sharedInbox'] : $res['inbox'];
+
+        $aprofile->do_insert();
+        $profile = $aprofile->local_profile();
+
+        // Public Key
+        $apRSA = new Activitypub_rsa();
+        $apRSA->profile_id = $profile->getID();
+        $apRSA->public_key = $res['publicKey']['publicKeyPem'];
+        $apRSA->store_keys();
+
+        // Avatar
+        if (isset($res['icon']['url'])) {
+            try {
+                $this->update_avatar($profile, $res['icon']['url']);
+            } catch (Exception $e) {
+                // Let the exception go, it isn't a serious issue
+                common_debug('ActivityPub Explorer: An error ocurred while grabbing remote avatar: '.$e->getMessage());
+            }
+        }
+
+        return $profile;
+    }
+
+    /**
+     * Download and update given avatar image
+     *
+     * @author GNU social
+     * @param  Profile $profile
+     * @param  string $url
+     * @return Avatar    The Avatar we have on disk.
+     * @throws Exception in various failure cases
+     */
+    public static function update_avatar(Profile $profile, $url)
+    {
+        common_debug('ActivityPub Explorer: Started grabbing remote avatar from: '.$url);
+        if (!filter_var($url, FILTER_VALIDATE_URL)) {
+            // TRANS: Server exception. %s is a URL.
+            common_debug('ActivityPub Explorer: Failed because it is an invalid url: '.$url);
+            throw new ServerException(sprintf('Invalid avatar URL %s.', $url));
+        }
+
+        // @todo FIXME: This should be better encapsulated
+        // ripped from oauthstore.php (for old OMB client)
+        $temp_filename = tempnam(sys_get_temp_dir(), 'listener_avatar');
+        try {
+            $imgData = HTTPClient::quickGet($url);
+            // Make sure it's at least an image file. ImageFile can do the rest.
+            if (false === getimagesizefromstring($imgData)) {
+                common_debug('ActivityPub Explorer: Failed because the downloaded avatar: '.$url. 'is not a valid image.');
+                throw new UnsupportedMediaException('Downloaded avatar was not an image.');
+            }
+            file_put_contents($temp_filename, $imgData);
+            unset($imgData);    // No need to carry this in memory.
+            common_debug('ActivityPub Explorer: Stored dowloaded avatar in: '.$temp_filename);
+
+            $id = $profile->getID();
+
+            $imagefile = new ImageFile(null, $temp_filename);
+            $filename = Avatar::filename(
+                $id,
+                image_type_to_extension($imagefile->type),
+                null,
+                common_timestamp()
+            );
+            rename($temp_filename, Avatar::path($filename));
+            common_debug('ActivityPub Explorer: Moved avatar from: '.$temp_filename.' to '.$filename);
+        } catch (Exception $e) {
+            common_debug('ActivityPub Explorer: Something went wrong while processing the avatar from: '.$url.' details: '.$e->getMessage());
+            unlink($temp_filename);
+            throw $e;
+        }
+        // @todo FIXME: Hardcoded chmod is lame, but seems to be necessary to
+        // keep from accidentally saving images from command-line (queues)
+        // that can't be read from web server, which causes hard-to-notice
+        // problems later on:
+        //
+        // http://status.net/open-source/issues/2663
+        chmod(Avatar::path($filename), 0644);
+
+        $profile->setOriginal($filename);
+
+        $orig = clone($profile);
+        $profile->avatar = $url;
+        $profile->update($orig);
+
+        common_debug('ActivityPub Explorer: Seted Avatar from: '.$url.' to profile.');
+        return Avatar::getUploaded($profile);
+    }
+
+    /**
+     * Validates a remote response in order to determine whether this
+     * response is a valid profile or not
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param array $res remote response
+     * @return boolean success state
+     */
+    public static function validate_remote_response($res)
+    {
+        if (!isset($res['id'], $res['preferredUsername'], $res['inbox'], $res['publicKey']['publicKeyPem'])) {
+            return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Get a ActivityPub Profile from it's uri
+     * Unfortunately GNU social cache is not truly reliable when handling
+     * potential ActivityPub remote profiles, as so it is important to use
+     * this hacky workaround (at least for now)
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param string $v URL
+     * @return boolean|Activitypub_profile false if fails | Aprofile object if successful
+     */
+    public static function get_aprofile_by_url($v)
+    {
+        $i = Managed_DataObject::getcached("Activitypub_profile", "uri", $v);
+        if (empty($i)) { // false = cache miss
+            $i = new Activitypub_profile;
+            $result = $i->get("uri", $v);
+            if ($result) {
+                // Hit!
+                $i->encache();
+            } else {
+                return false;
+            }
+        }
+        return $i;
+    }
+
+    /**
+     * Given a valid actor profile url returns its inboxes
+     *
+     * @param string $url of Actor profile
+     * @return boolean|array false if fails | array with inbox and shared inbox if successful
+     * @throws HTTP_Request2_Exception
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function get_actor_inboxes_uri($url)
+    {
+        $client    = new HTTPClient();
+        $headers   = [];
+        $headers[] = 'Accept: application/ld+json; profile="https://www.w3.org/ns/activitystreams"';
+        $headers[] = 'User-Agent: GNUSocialBot v0.1 - https://gnu.io/social';
+        $response  = $client->get($url, $headers);
+        if (!$response->isOk()) {
+            throw new Exception('Invalid Actor URL.');
+        }
+        $res = json_decode($response->getBody(), true);
+        if (self::validate_remote_response($res)) {
+            return [
+                'inbox' => $res['inbox'],
+                'sharedInbox' => isset($res['endpoints']['sharedInbox']) ? $res['endpoints']['sharedInbox'] : $res['inbox']
+            ];
+        }
+
+        return false;
+    }
+
+    /**
+     * Allows the Explorer to transverse a collection of persons.
+     *
+     * @param string $url
+     * @return boolean
+     * @throws HTTP_Request2_Exception
+     * @throws NoProfileException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function travel_collection($url)
+    {
+        $client    = new HTTPClient();
+        $headers   = [];
+        $headers[] = 'Accept: application/ld+json; profile="https://www.w3.org/ns/activitystreams"';
+        $headers[] = 'User-Agent: GNUSocialBot v0.1 - https://gnu.io/social';
+        $response  = $client->get($url, $headers);
+        $res = json_decode($response->getBody(), true);
+
+        if (!isset($res['orderedItems'])) {
+            return false;
+        }
+
+        foreach ($res["orderedItems"] as $profile) {
+            if ($this->_lookup($profile) == false) {
+                common_debug('ActivityPub Explorer: Found an invalid actor for '.$profile);
+                // TODO: Invalid actor found, fallback to OStatus
+            }
+        }
+        // Go through entire collection
+        if (!is_null($res["next"])) {
+            $this->_lookup($res["next"]);
+        }
+
+        return true;
+    }
+
+    /**
+     * Get a remote user array from its URL (this function is only used for
+     * profile updating and shall not be used for anything else)
+     *
+     * @param string $url User's url
+     * @return mixed
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public static function get_remote_user_activity($url)
+    {
+        $client    = new HTTPClient();
+        $headers   = [];
+        $headers[] = 'Accept: application/ld+json; profile="https://www.w3.org/ns/activitystreams"';
+        $headers[] = 'User-Agent: GNUSocialBot v0.1 - https://gnu.io/social';
+        $response  = $client->get($url, $headers);
+        $res = json_decode($response->getBody(), true);
+        if (Activitypub_explorer::validate_remote_response($res)) {
+            common_debug('ActivityPub Explorer: Found a valid remote actor for '.$url);
+            return $res;
+        }
+        throw new Exception('ActivityPub Explorer: Failed to get activity.');
+    }
+}

plugins/ActivityPub/lib/httpsignature.php

@@ -0,0 +1,139 @@
+<?php
+/**
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * @category  Network
+ * @package   Nautilus
+ * @author    Aaron Parecki <aaron@parecki.com>
+ * @license   http://www.apache.org/licenses/LICENSE-2.0 Apache License 2.0
+ * @link      https://github.com/aaronpk/Nautilus/blob/master/app/ActivityPub/HTTPSignature.php
+ */
+
+class HttpSignature
+{
+    public static function sign($user, $url, $body = false, $addlHeaders = [])
+    {
+        $digest = false;
+        if ($body) {
+            $digest = self::_digest($body);
+        }
+        $headers = self::_headersToSign($url, $digest);
+        $headers = array_merge($headers, $addlHeaders);
+        $stringToSign = self::_headersToSigningString($headers);
+        $signedHeaders = implode(' ', array_map('strtolower', array_keys($headers)));
+        $actor_private_key = new Activitypub_rsa();
+        $actor_private_key = $actor_private_key->get_private_key($user);
+        $key = openssl_pkey_get_private($actor_private_key);
+        openssl_sign($stringToSign, $signature, $key, OPENSSL_ALGO_SHA256);
+        $signature = base64_encode($signature);
+        $signatureHeader = 'keyId="' . ActivityPubPlugin::actor_uri($user).'#public-key' . '",headers="' . $signedHeaders . '",algorithm="rsa-sha256",signature="' . $signature . '"';
+        unset($headers['(request-target)']);
+        $headers['Signature'] = $signatureHeader;
+
+        return self::_headersToCurlArray($headers);
+    }
+
+    private static function _digest($body)
+    {
+        if (is_array($body)) {
+            $body = json_encode($body);
+        }
+        return base64_encode(hash('sha256', $body, true));
+    }
+
+    protected static function _headersToSign($url, $digest = false)
+    {
+        $date = new DateTime('UTC');
+
+        $headers = [
+            '(request-target)' => 'post ' . parse_url($url, PHP_URL_PATH),
+            'Date' => $date->format('D, d M Y H:i:s \G\M\T'),
+            'Host' => parse_url($url, PHP_URL_HOST),
+            'Accept' => 'application/ld+json; profile="https://www.w3.org/ns/activitystreams", application/activity+json, application/json',
+            'User-Agent'   => 'GNU social ActivityPub Plugin - https://gnu.io/social',
+            'Content-Type' => 'application/activity+json'
+        ];
+
+        if ($digest) {
+            $headers['Digest'] = 'SHA-256=' . $digest;
+        }
+
+        return $headers;
+    }
+
+    private static function _headersToSigningString($headers)
+    {
+        return implode("\n", array_map(function ($k, $v) {
+            return strtolower($k) . ': ' . $v;
+        }, array_keys($headers), $headers));
+    }
+
+    private static function _headersToCurlArray($headers)
+    {
+        return array_map(function ($k, $v) {
+            return "$k: $v";
+        }, array_keys($headers), $headers);
+    }
+
+    public static function parseSignatureHeader($signature)
+    {
+        $parts = explode(',', $signature);
+        $signatureData = [];
+
+        foreach ($parts as $part) {
+            if (preg_match('/(.+)="(.+)"/', $part, $match)) {
+                $signatureData[$match[1]] = $match[2];
+            }
+        }
+
+        if (!isset($signatureData['keyId'])) {
+            return [
+                'error' => 'No keyId was found in the signature header. Found: ' . implode(', ', array_keys($signatureData))
+            ];
+        }
+
+        if (!filter_var($signatureData['keyId'], FILTER_VALIDATE_URL)) {
+            return [
+                'error' => 'keyId is not a URL: ' . $signatureData['keyId']
+            ];
+        }
+
+        if (!isset($signatureData['headers']) || !isset($signatureData['signature'])) {
+            return [
+                'error' => 'Signature is missing headers or signature parts'
+            ];
+        }
+
+        return $signatureData;
+    }
+
+    public static function verify($publicKey, $signatureData, $inputHeaders, $path, $body)
+    {
+        $digest = 'SHA-256=' . base64_encode(hash('sha256', $body, true));
+        $headersToSign = [];
+        foreach (explode(' ', $signatureData['headers']) as $h) {
+            if ($h == '(request-target)') {
+                $headersToSign[$h] = 'post ' . $path;
+            } elseif ($h == 'digest') {
+                $headersToSign[$h] = $digest;
+            } elseif (isset($inputHeaders[$h][0])) {
+                $headersToSign[$h] = $inputHeaders[$h];
+            }
+        }
+        $signingString = self::_headersToSigningString($headersToSign);
+
+        $verified = openssl_verify($signingString, base64_decode($signatureData['signature']), $publicKey, OPENSSL_ALGO_SHA256);
+
+        return [$verified, $signingString];
+    }
+}

plugins/ActivityPub/lib/inbox_handler.php

@@ -0,0 +1,324 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub Inbox Handler
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_inbox_handler
+{
+    private $activity;
+    private $actor;
+    private $object;
+
+    /**
+     * Create a Inbox Handler to receive something from someone.
+     *
+     * @param array $activity Activity we are receiving
+     * @param Profile $actor_profile Actor originating the activity
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function __construct($activity, $actor_profile = null)
+    {
+        $this->activity = $activity;
+        $this->object = $activity['object'];
+
+        // Validate Activity
+        $this->validate_activity();
+
+        // Get Actor's Profile
+        if (!is_null($actor_profile)) {
+            $this->actor = $actor_profile;
+        } else {
+            $this->actor = ActivityPub_explorer::get_profile_from_url($this->activity['actor']);
+        }
+
+        // Handle the Activity
+        $this->process();
+    }
+
+    /**
+     * Validates if a given Activity is valid. Throws exception if not.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @throws Exception
+     */
+    private function validate_activity()
+    {
+        // Activity validation
+        // Validate data
+        if (!(isset($this->activity['type']))) {
+            throw new Exception('Activity Validation Failed: Type was not specified.');
+        }
+        if (!isset($this->activity['actor'])) {
+            throw new Exception('Activity Validation Failed: Actor was not specified.');
+        }
+        if (!isset($this->activity['object'])) {
+            throw new Exception('Activity Validation Failed: Object was not specified.');
+        }
+
+        // Object validation
+        switch ($this->activity['type']) {
+            case 'Accept':
+                Activitypub_accept::validate_object($this->object);
+                break;
+            case 'Create':
+                Activitypub_create::validate_object($this->object);
+                break;
+            case 'Delete':
+            case 'Follow':
+            case 'Like':
+            case 'Announce':
+                if (!filter_var($this->object, FILTER_VALIDATE_URL)) {
+                    throw new Exception('Object is not a valid Object URI for Activity.');
+                }
+                break;
+            case 'Undo':
+                Activitypub_undo::validate_object($this->object);
+                break;
+            default:
+                throw new Exception('Unknown Activity Type.');
+        }
+    }
+
+    /**
+     * Sends the Activity to proper handler in order to be processed.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function process()
+    {
+        switch ($this->activity['type']) {
+            case 'Accept':
+                $this->handle_accept($this->actor, $this->object);
+                break;
+            case 'Create':
+                $this->handle_create($this->actor, $this->object);
+                break;
+            case 'Delete':
+                $this->handle_delete($this->actor, $this->object);
+                break;
+            case 'Follow':
+                $this->handle_follow($this->actor, $this->object);
+                break;
+            case 'Like':
+                $this->handle_like($this->actor, $this->object);
+                break;
+            case 'Undo':
+                $this->handle_undo($this->actor, $this->object);
+                break;
+            case 'Announce':
+                $this->handle_announce($this->actor, $this->object);
+                break;
+        }
+    }
+
+    /**
+     * Handles an Accept Activity received by our inbox.
+     *
+     * @param Profile $actor Actor
+     * @param array $object Activity
+     * @throws HTTP_Request2_Exception
+     * @throws NoProfileException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function handle_accept($actor, $object)
+    {
+        switch ($object['type']) {
+            case 'Follow':
+                $this->handle_accept_follow($actor, $object);
+                break;
+        }
+    }
+
+    /**
+     * Handles an Accept Follow Activity received by our inbox.
+     *
+     * @param Profile $actor Actor
+     * @param array $object Activity
+     * @throws HTTP_Request2_Exception
+     * @throws NoProfileException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function handle_accept_follow($actor, $object)
+    {
+        // Get valid Object profile
+        $object_profile = new Activitypub_explorer;
+        $object_profile = $object_profile->lookup($object['object'])[0];
+
+        $pending_list = new Activitypub_pending_follow_requests($actor->getID(), $object_profile->getID());
+        $pending_list->remove();
+    }
+
+    /**
+     * Handles a Create Activity received by our inbox.
+     *
+     * @param Profile $actor Actor
+     * @param array $object Activity
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function handle_create($actor, $object)
+    {
+        switch ($object['type']) {
+            case 'Note':
+                Activitypub_notice::create_notice($object, $actor);
+                break;
+        }
+    }
+
+    /**
+     * Handles a Delete Activity received by our inbox.
+     *
+     * @param Profile $actor Actor
+     * @param array $object Activity
+     * @throws AuthorizationException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function handle_delete($actor, $object)
+    {
+        $notice = ActivityPubPlugin::grab_notice_from_url($object['object']);
+        $notice->deleteAs($actor);
+    }
+
+    /**
+     * Handles a Follow Activity received by our inbox.
+     *
+     * @param Profile $actor Actor
+     * @param array $object Activity
+     * @throws AlreadyFulfilledException
+     * @throws HTTP_Request2_Exception
+     * @throws NoProfileException
+     * @throws ServerException
+     * @throws \GuzzleHttp\Exception\GuzzleException
+     * @throws \HttpSignatures\Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function handle_follow($actor, $object)
+    {
+        Activitypub_follow::follow($actor, $object);
+    }
+
+    /**
+     * Handles a Like Activity received by our inbox.
+     *
+     * @param Profile $actor Actor
+     * @param array $object Activity
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function handle_like($actor, $object)
+    {
+        $notice = ActivityPubPlugin::grab_notice_from_url($object);
+        Fave::addNew($actor, $notice);
+    }
+
+    /**
+     * Handles a Undo Activity received by our inbox.
+     *
+     * @param Profile $actor Actor
+     * @param array $object Activity
+     * @throws AlreadyFulfilledException
+     * @throws HTTP_Request2_Exception
+     * @throws NoProfileException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function handle_undo($actor, $object)
+    {
+        switch ($object['type']) {
+            case 'Follow':
+                $this->handle_undo_follow($actor, $object['object']);
+                break;
+            case 'Like':
+                $this->handle_undo_like($actor, $object['object']);
+                break;
+        }
+    }
+
+    /**
+     * Handles a Undo Like Activity received by our inbox.
+     *
+     * @param Profile $actor Actor
+     * @param array $object Activity
+     * @throws AlreadyFulfilledException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    private function handle_undo_like($actor, $object)
+    {
+        $notice = ActivityPubPlugin::grab_notice_from_url($object);
+        Fave::removeEntry($actor, $notice);
+    }
+
+    /**
+     * Handles a Undo Follow Activity received by our inbox.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param Profile $actor Actor
+     * @param array $object Activity
+     * @throws AlreadyFulfilledException
+     * @throws HTTP_Request2_Exception
+     * @throws NoProfileException
+     * @throws ServerException
+     */
+    private function handle_undo_follow($actor, $object)
+    {
+        // Get Object profile
+        $object_profile = new Activitypub_explorer;
+        $object_profile = $object_profile->lookup($object)[0];
+
+        if (Subscription::exists($actor, $object_profile)) {
+            Subscription::cancel($actor, $object_profile);
+        // You are no longer following this person.
+        } else {
+            // 409: You are not following this person already.
+        }
+    }
+
+    /**
+     * Handles a Announce Activity received by our inbox.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @param Profile $actor Actor
+     * @param array $object Activity
+     * @throws Exception
+     */
+    private function handle_announce($actor, $object)
+    {
+        $object_notice = ActivityPubPlugin::grab_notice_from_url($object);
+        $object_notice->repeat($actor, 'ActivityPub');
+    }
+}

plugins/ActivityPub/lib/postman.php

@@ -0,0 +1,348 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * ActivityPub's own Postman
+ *
+ * Standard workflow expects that we send an Explorer to find out destinataries'
+ * inbox address. Then we send our postman to deliver whatever we want to send them.
+ *
+ * @category  Plugin
+ * @package   GNUsocial
+ * @author    Diogo Cordeiro <diogo@fc.up.pt>
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class Activitypub_postman
+{
+    private $actor;
+    private $actor_uri;
+    private $to = [];
+    private $client;
+    private $headers;
+
+    /**
+     * Create a postman to deliver something to someone
+     *
+     * @param Profile $from Profile of sender
+     * @param $to
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function __construct($from, $to)
+    {
+        $this->actor = $from;
+        $discovery = new Activitypub_explorer();
+        $this->to = $to;
+        $followers = apActorFollowersAction::generate_followers($this->actor, 0, null);
+        foreach ($followers as $sub) {
+            try {
+                $to[]= Activitypub_profile::from_profile($discovery->lookup($sub)[0]);
+            } catch (Exception $e) {
+                // Not an ActivityPub Remote Follower, let it go
+            }
+        }
+        unset($discovery);
+
+        $this->actor_uri = ActivityPubPlugin::actor_uri($this->actor);
+
+        $this->client = new HTTPClient();
+    }
+
+    /**
+     * Send something to remote instance
+     *
+     * @param string $data request body
+     * @param string $inbox url of remote inbox
+     * @param string $method request method
+     * @return GNUsocial_HTTPResponse
+     * @throws HTTP_Request2_Exception
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function send($data, $inbox, $method = 'POST')
+    {
+        common_debug('ActivityPub Postman: Delivering '.$data.' to '.$inbox);
+
+        $headers = HttpSignature::sign($this->actor, $inbox, $data);
+
+        common_debug('ActivityPub Postman: Delivery headers were: '.print_r($headers, true));
+
+        $this->client->setBody($data);
+
+        switch ($method) {
+            case 'POST':
+                $response = $this->client->post($inbox, $headers);
+                break;
+            case 'GET':
+                $response = $this->client->get($inbox, $headers);
+                break;
+            default:
+                throw new Exception("Unsupported request method for postman.");
+        }
+
+        common_debug('ActivityPub Postman: Delivery result with status code '.$response->getStatus().': '.$response->getBody());
+        return $response;
+    }
+
+    /**
+     * Send a follow notification to remote instance
+     *
+     * @return bool
+     * @throws HTTP_Request2_Exception
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function follow()
+    {
+        $data = Activitypub_follow::follow_to_array(ActivityPubPlugin::actor_uri($this->actor), $this->to[0]->getUrl());
+        $res = $this->send(json_encode($data, JSON_UNESCAPED_SLASHES), $this->to[0]->get_inbox());
+        $res_body = json_decode($res->getBody());
+
+        if ($res->getStatus() == 200 || $res->getStatus() == 202 || $res->getStatus() == 409) {
+            $pending_list = new Activitypub_pending_follow_requests($this->actor->getID(), $this->to[0]->getID());
+            $pending_list->add();
+            return true;
+        } elseif (isset($res_body[0]->error)) {
+            throw new Exception($res_body[0]->error);
+        }
+
+        throw new Exception("An unknown error occurred.");
+    }
+
+    /**
+     * Send a Undo Follow notification to remote instance
+     *
+     * @return bool
+     * @throws HTTP_Request2_Exception
+     * @throws Exception
+     * @throws Exception
+     * @throws Exception
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function undo_follow()
+    {
+        $data = Activitypub_undo::undo_to_array(
+            Activitypub_follow::follow_to_array(
+                ActivityPubPlugin::actor_uri($this->actor),
+                $this->to[0]->getUrl()
+                    )
+                );
+        $res = $this->send(json_encode($data, JSON_UNESCAPED_SLASHES), $this->to[0]->get_inbox());
+        $res_body = json_decode($res->getBody());
+
+        if ($res->getStatus() == 200 || $res->getStatus() == 202 || $res->getStatus() == 409) {
+            $pending_list = new Activitypub_pending_follow_requests($this->actor->getID(), $this->to[0]->getID());
+            $pending_list->remove();
+            return true;
+        }
+        if (isset($res_body[0]->error)) {
+            throw new Exception($res_body[0]->error);
+        }
+        throw new Exception("An unknown error occurred.");
+    }
+
+    /**
+     * Send a Accept Follow notification to remote instance
+     *
+     * @return bool
+     * @throws HTTP_Request2_Exception
+     * @throws Exception
+     * @throws Exception
+     * @throws Exception
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function accept_follow()
+    {
+        $data = Activitypub_accept::accept_to_array(
+            Activitypub_follow::follow_to_array(
+                $this->to[0]->getUrl(),
+                ActivityPubPlugin::actor_uri($this->actor)
+
+                    )
+               );
+        $res = $this->send(json_encode($data, JSON_UNESCAPED_SLASHES), $this->to[0]->get_inbox());
+        $res_body = json_decode($res->getBody());
+
+        if ($res->getStatus() == 200 || $res->getStatus() == 202 || $res->getStatus() == 409) {
+            $pending_list = new Activitypub_pending_follow_requests($this->actor->getID(), $this->to[0]->getID());
+            $pending_list->remove();
+            return true;
+        }
+        if (isset($res_body[0]->error)) {
+            throw new Exception($res_body[0]->error);
+        }
+        throw new Exception("An unknown error occurred.");
+    }
+
+    /**
+     * Send a Like notification to remote instances holding the notice
+     *
+     * @param Notice $notice
+     * @throws HTTP_Request2_Exception
+     * @throws InvalidUrlException
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function like($notice)
+    {
+        $data = Activitypub_like::like_to_array(
+            ActivityPubPlugin::actor_uri($this->actor),
+            $notice->getUrl()
+                );
+        $data = json_encode($data, JSON_UNESCAPED_SLASHES);
+
+        foreach ($this->to_inbox() as $inbox) {
+            $this->send($data, $inbox);
+        }
+    }
+
+    /**
+     * Send a Undo Like notification to remote instances holding the notice
+     *
+     * @param Notice $notice
+     * @throws HTTP_Request2_Exception
+     * @throws InvalidUrlException
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function undo_like($notice)
+    {
+        $data = Activitypub_undo::undo_to_array(
+            Activitypub_like::like_to_array(
+                ActivityPubPlugin::actor_uri($this->actor),
+                $notice->getUrl()
+                         )
+                );
+        $data = json_encode($data, JSON_UNESCAPED_SLASHES);
+
+        foreach ($this->to_inbox() as $inbox) {
+            $this->send($data, $inbox);
+        }
+    }
+
+    /**
+     * Send a Create notification to remote instances
+     *
+     * @param Notice $notice
+     * @throws EmptyPkeyValueException
+     * @throws HTTP_Request2_Exception
+     * @throws InvalidUrlException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function create_note($notice)
+    {
+        $data = Activitypub_create::create_to_array(
+            $this->actor_uri,
+            Activitypub_notice::notice_to_array($notice)
+                );
+        $data = json_encode($data, JSON_UNESCAPED_SLASHES);
+
+        foreach ($this->to_inbox() as $inbox) {
+            $this->send($data, $inbox);
+        }
+    }
+
+    /**
+     * Send a Announce notification to remote instances
+     *
+     * @param Notice $notice
+     * @throws HTTP_Request2_Exception
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function announce($notice)
+    {
+        $data = Activitypub_announce::announce_to_array(
+            ActivityPubPlugin::actor_uri($this->actor),
+            $notice->getUri()
+                        );
+        $data = json_encode($data, JSON_UNESCAPED_SLASHES);
+
+        foreach ($this->to_inbox() as $inbox) {
+            $this->send($data, $inbox);
+        }
+    }
+
+    /**
+     * Send a Delete notification to remote instances holding the notice
+     *
+     * @param Notice $notice
+     * @throws HTTP_Request2_Exception
+     * @throws InvalidUrlException
+     * @throws Exception
+     * @throws Exception
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function delete($notice)
+    {
+        $data = Activitypub_delete::delete_to_array(
+            ActivityPubPlugin::actor_uri($notice->getProfile()),
+            $notice->getUrl()
+                );
+        $errors = [];
+        $data = json_encode($data, JSON_UNESCAPED_SLASHES);
+        foreach ($this->to_inbox() as $inbox) {
+            $res = $this->send($data, $inbox);
+            if (!$res->getStatus() == 200) {
+                $res_body = json_decode($res->getBody(), true);
+                if (isset($res_body[0]['error'])) {
+                    $errors[] = ($res_body[0]['error']);
+                    continue;
+                }
+                $errors[] = ("An unknown error occurred.");
+            }
+        }
+        if (!empty($errors)) {
+            throw new Exception(json_encode($errors));
+        }
+    }
+
+    /**
+     * Clean list of inboxes to deliver messages
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @return array To Inbox URLs
+     */
+    private function to_inbox()
+    {
+        $to_inboxes = [];
+        foreach ($this->to as $to_profile) {
+            $i = $to_profile->get_inbox();
+            // Prevent delivering to self
+            if ($i == [common_local_url('apInbox')]) {
+                continue;
+            }
+            $to_inboxes[] = $i;
+        }
+
+        return array_unique($to_inboxes);
+    }
+}

plugins/ActivityPub/locale/ActivityPub.pot

@@ -0,0 +1,51 @@
+# SOME DESCRIPTIVE TITLE.
+# Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER
+# This file is distributed under the same license as the PACKAGE package.
+# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
+#
+#, fuzzy
+msgid ""
+msgstr ""
+"Project-Id-Version: PACKAGE VERSION\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2019-06-12 01:23+0100\n"
+"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
+"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"Language-Team: LANGUAGE <LL@li.org>\n"
+"Language: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=CHARSET\n"
+"Content-Transfer-Encoding: 8bit\n"
+
+#. TRANS: Plugin description.
+#: ActivityPubPlugin.php:212
+msgid ""
+"Follow people across social networks that implement <a href=\"https://"
+"activitypub.rocks/\">ActivityPub</a>."
+msgstr ""
+
+#: ActivityPubPlugin.php:254
+msgid "Remote Profile"
+msgstr ""
+
+#. TRANS: Title. %s is a domain name.
+#: ActivityPubPlugin.php:909
+#, php-format
+msgid "Sent from %s via ActivityPub"
+msgstr ""
+
+#. TRANS: Exception.
+#: classes/Activitypub_profile.php:355
+msgid "Not a valid webfinger address (via cache)."
+msgstr ""
+
+#. TRANS: Exception.
+#: classes/Activitypub_profile.php:376
+msgid "Not a valid webfinger address."
+msgstr ""
+
+#. TRANS: Exception. %s is a webfinger address.
+#: classes/Activitypub_profile.php:416
+#, php-format
+msgid "Could not find a valid profile for \"%s\"."
+msgstr ""

plugins/ActivityPub/locale/en_GB/LC_MESSAGES/ActivityPub.po

@@ -0,0 +1,54 @@
+# Translation file for GNU social - the free software social networking platform
+# Copyright (C) 2015 - 2019 Free Software Foundation, Inc http://www.fsf.org
+# This file is under https://www.gnu.org/licenses/agpl v3 or later
+# 
+# Translators:
+# Diogo Cordeiro <diogo@fc.up.pt>, 2019
+msgid ""
+msgstr ""
+"Project-Id-Version: GNU social\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2019-06-12 01:23+0100\n"
+"PO-Revision-Date: 2019-06-12 01:23+0100\n"
+"Last-Translator: Diogo Cordeiro <diogo@fc.up.pt>\n"
+"Language-Team: English (United Kingdom) (http://www.transifex.com/gnu-social/gnu-social/language/en_GB/)\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Language: en_GB\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+#. TRANS: Plugin description.
+#: ActivityPubPlugin.php:212
+msgid ""
+"Follow people across social networks that implement <a href=\"https://"
+"activitypub.rocks/\">ActivityPub</a>."
+msgstr ""
+"Follow people across social networks that implement <a href=\"https://"
+"activitypub.rocks/\">ActivityPub</a>."
+
+#: ActivityPubPlugin.php:254
+msgid "Remote Profile"
+msgstr "Remote Profile"
+
+#. TRANS: Title. %s is a domain name.
+#: ActivityPubPlugin.php:909
+#, php-format
+msgid "Sent from %s via ActivityPub"
+msgstr "Sent from %s via ActivityPub"
+
+#. TRANS: Exception.
+#: classes/Activitypub_profile.php:355
+msgid "Not a valid webfinger address (via cache)."
+msgstr "Not a valid WebFinger address (via cache)."
+
+#. TRANS: Exception.
+#: classes/Activitypub_profile.php:376
+msgid "Not a valid webfinger address."
+msgstr "Not a valid WebFinger address."
+
+#. TRANS: Exception. %s is a webfinger address.
+#: classes/Activitypub_profile.php:416
+#, php-format
+msgid "Could not find a valid profile for \"%s\"."
+msgstr "Could not find a valid profile for \"%s\"."

plugins/ActivityPub/locale/pt/LC_MESSAGES/ActivityPub.po

@@ -0,0 +1,54 @@
+# Translation file for GNU social - the free software social networking platform
+# Copyright (C) 2015 - 2019 Free Software Foundation, Inc http://www.fsf.org
+# This file is under https://www.gnu.org/licenses/agpl v3 or later
+# 
+# Translators:
+# Diogo Cordeiro <diogo@fc.up.pt>, 2019
+msgid ""
+msgstr ""
+"Project-Id-Version: GNU social\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2019-06-12 01:23+0100\n"
+"PO-Revision-Date: 2019-06-12 01:23+0100\n"
+"Last-Translator: Diogo Cordeiro <diogo@fc.up.pt>\n"
+"Language-Team: Portuguese (http://www.transifex.com/gnu-social/gnu-social/language/pt/)\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Language: pt\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+#. TRANS: Plugin description.
+#: ActivityPubPlugin.php:212
+msgid ""
+"Follow people across social networks that implement <a href=\"https://"
+"activitypub.rocks/\">ActivityPub</a>."
+msgstr ""
+"Segue pessoas em redes sociais que implementam <a href=\"https://"
+"activitypub.rocks/\">ActivityPub</a>."
+
+#: ActivityPubPlugin.php:254
+msgid "Remote Profile"
+msgstr "Perfil Remoto"
+
+#. TRANS: Title. %s is a domain name.
+#: ActivityPubPlugin.php:909
+#, php-format
+msgid "Sent from %s via ActivityPub"
+msgstr "Enviado por %s via ActivityPub"
+
+#. TRANS: Exception.
+#: classes/Activitypub_profile.php:355
+msgid "Not a valid webfinger address (via cache)."
+msgstr "Endereço WebFinger inválido (via cache)."
+
+#. TRANS: Exception.
+#: classes/Activitypub_profile.php:376
+msgid "Not a valid webfinger address."
+msgstr "Endereço WebFinger inválido."
+
+#. TRANS: Exception. %s is a webfinger address.
+#: classes/Activitypub_profile.php:416
+#, php-format
+msgid "Could not find a valid profile for \"%s\"."
+msgstr "Não foi possível encontrar um perfil válido para \"%s\"."

plugins/ActivityPub/locale/pt_BR/LC_MESSAGES/ActivityPub.po

@@ -0,0 +1,54 @@
+# Translation file for GNU social - the free software social networking platform
+# Copyright (C) 2015 - 2019 Free Software Foundation, Inc http://www.fsf.org
+# This file is under https://www.gnu.org/licenses/agpl v3 or later
+# 
+# Translators:
+# Diogo Cordeiro <diogo@fc.up.pt>, 2019
+msgid ""
+msgstr ""
+"Project-Id-Version: GNU social\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2019-06-12 01:23+0100\n"
+"PO-Revision-Date: 2019-06-12 02:24+0100\n"
+"Last-Translator: Diogo Cordeiro <diogo@fc.up.pt>\n"
+"Language-Team: Portuguese (Brazil) (http://www.transifex.com/gnu-social/gnu-social/language/pt_BR/)\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Language: pt_BR\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+#. TRANS: Plugin description.
+#: ActivityPubPlugin.php:212
+msgid ""
+"Follow people across social networks that implement <a href=\"https://"
+"activitypub.rocks/\">ActivityPub</a>."
+msgstr ""
+"Segue pessoas em redes sociais que implementam <a href=\"https://"
+"activitypub.rocks/\">ActivityPub</a>."
+
+#: ActivityPubPlugin.php:254
+msgid "Remote Profile"
+msgstr "Perfil Remoto"
+
+#. TRANS: Title. %s is a domain name.
+#: ActivityPubPlugin.php:909
+#, php-format
+msgid "Sent from %s via ActivityPub"
+msgstr "Enviado por %s via ActivityPub"
+
+#. TRANS: Exception.
+#: classes/Activitypub_profile.php:355
+msgid "Not a valid webfinger address (via cache)."
+msgstr "Endereço WebFinger inválido (via cache)."
+
+#. TRANS: Exception.
+#: classes/Activitypub_profile.php:376
+msgid "Not a valid webfinger address."
+msgstr "Endereço WebFinger inválido."
+
+#. TRANS: Exception. %s is a webfinger address.
+#: classes/Activitypub_profile.php:416
+#, php-format
+msgid "Could not find a valid profile for \"%s\"."
+msgstr "Não foi possível encontrar um perfil válido para \"%s\"."

plugins/ActivityPub/phpunit.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit backupGlobals="false"
+         backupStaticAttributes="false"
+         bootstrap="vendor/autoload.php"
+         colors="true"
+         convertErrorsToExceptions="true"
+         convertNoticesToExceptions="true"
+         convertWarningsToExceptions="true"
+         processIsolation="false"
+         stopOnFailure="false">
+    <testsuites>
+        <testsuite name="Feature">
+            <directory suffix="Test.php">./tests/Feature</directory>
+        </testsuite>
+
+        <testsuite name="Unit">
+            <directory suffix="Test.php">./tests/Unit</directory>
+        </testsuite>
+    </testsuites>
+    <filter>
+        <whitelist processUncoveredFilesFromWhitelist="true">
+            <directory suffix=".php">./app</directory>
+        </whitelist>
+    </filter>
+</phpunit>

plugins/ActivityPub/scripts/update_activitypub_profiles.php

@@ -0,0 +1,104 @@
+#!/usr/bin/env php
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+define('INSTALLDIR', realpath(__DIR__ . '/../../..'));
+
+$shortoptions = 'u:af';
+$longoptions = ['uri=', 'all', 'force'];
+
+$helptext = <<<END_OF_HELP
+update_activitypub_profiles.php [options]
+Refetch / update ActivityPub RSA keys, profile info and avatars. Useful if you
+do something like accidentally delete your avatars directory when
+you have no backup.
+
+    -u --uri ActivityPub profile URI to update
+    -a --all update all
+
+END_OF_HELP;
+
+require_once INSTALLDIR.'/scripts/commandline.inc';
+
+$quiet = have_option('q', 'quiet');
+
+if (!$quiet) {
+    echo "ActivityPub Profiles updater will now start!\n";
+    echo "Summoning Diogo Cordeiro, Richard Stallman and Chuck Norris to help us with this task!\n";
+}
+
+if (have_option('u', 'uri')) {
+    $uri = get_option_value('u', 'uri');
+    $discovery = new Activitypub_explorer();
+    $discovery = $discovery->lookup($uri);
+    if (empty($discovery)) {
+        echo "Bad URI\n";
+        exit(1);
+    }
+    $user = $discovery->lookup($uri)[0];
+    try {
+        $res = Activitypub_explorer::get_remote_user_activity($uri);
+    } catch (Exception $e) {
+        echo $e->getMessage()."\n";
+        exit(1);
+    }
+    if (!$quiet) {
+        echo "Updated ".Activitypub_profile::update_profile($user, $res)->getBestName()."\n";
+    }
+} elseif (!have_option('a', 'all')) {
+    show_help();
+    exit(1);
+}
+
+$user = new Activitypub_profile();
+$cnt = $user->find();
+if (!empty($cnt)) {
+    if (!$quiet) {
+        echo "Found {$cnt} ActivityPub profiles:\n";
+    }
+} else {
+    if (have_option('u', 'uri')) {
+        if (!$quiet) {
+            echo "Couldn't find an existing ActivityPub profile with that URI.\n";
+        }
+    } else {
+        if (!$quiet) {
+            echo "Couldn't find any existing ActivityPub profiles.\n";
+        }
+    }
+    exit(0);
+}
+while ($user->fetch()) {
+    try {
+        $res = Activitypub_explorer::get_remote_user_activity($user->uri);
+        $updated_profile = Activitypub_profile::update_profile($user, $res);
+        if (!$quiet) {
+            echo "Updated ".$updated_profile->getBestName()."\n";
+        }
+    } catch (Exception $e) {
+        // let it go
+    }
+}

plugins/ActivityPub/tests/CreatesApplication.php

@@ -0,0 +1,52 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+namespace Tests;
+
+trait CreatesApplication
+{
+    /**
+     * Creates the application.
+     *
+     * @return todo
+     */
+    public static function createApplication()
+    {
+        if (!defined('INSTALLDIR')) {
+            define('INSTALLDIR', __DIR__ . '/../../../');
+        }
+        if (!defined('GNUSOCIAL')) {
+            define('GNUSOCIAL', true);
+        }
+        if (!defined('STATUSNET')) {
+            define('STATUSNET', true);  // compatibility
+        }
+
+        require INSTALLDIR . '/lib/common.php';
+
+        return true;
+    }
+}

plugins/ActivityPub/tests/TestCase.php

@@ -0,0 +1,39 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+namespace Tests;
+
+use PHPUnit\Framework\TestCase as BaseTestCase;
+
+abstract class TestCase extends BaseTestCase
+{
+    use CreatesApplication;
+
+    protected function setUp()
+    {
+        $this->createApplication();
+    }
+}

plugins/ActivityPub/tests/Unit/AcceptHeaderTest.php

@@ -0,0 +1,67 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+require 'AcceptHeader.php';
+
+class ContainerTest extends \PHPUnit_Framework_TestCase
+{
+    public function testHeader1()
+    {
+        $acceptHeader = new AcceptHeader('audio/*; q=0.2, audio/basic');
+        $this->assertEquals('audio/basic', $this->_getMedia($acceptHeader[0]));
+        $this->assertEquals('audio/*; q=0.2', $this->_getMedia($acceptHeader[1]));
+    }
+
+    public function testHeader2()
+    {
+        $acceptHeader = new AcceptHeader('text/*;q=0.3, text/html;q=0.7, text/html;level=1, text/html;level=2;q=0.4, */*;q=0.5');
+        $this->assertEquals('text/html; level=1', $this->_getMedia($acceptHeader[0]));
+        $this->assertEquals('text/html; q=0.7', $this->_getMedia($acceptHeader[1]));
+        $this->assertEquals('*/*; q=0.5', $this->_getMedia($acceptHeader[2]));
+        $this->assertEquals('text/html; level=2; q=0.4', $this->_getMedia($acceptHeader[3]));
+        $this->assertEquals('text/*; q=0.3', $this->_getMedia($acceptHeader[4]));
+    }
+
+    public function testHeader3()
+    {
+        $acceptHeader = new AcceptHeader('text/*, text/html, text/html;level=1, */*');
+        $this->assertEquals('text/html; level=1', $this->_getMedia($acceptHeader[0]));
+        $this->assertEquals('text/html', $this->_getMedia($acceptHeader[1]));
+        $this->assertEquals('text/*', $this->_getMedia($acceptHeader[2]));
+        $this->assertEquals('*/*', $this->_getMedia($acceptHeader[3]));
+    }
+
+    private function _getMedia(array $mediaType)
+    {
+        $str = $mediaType['type'] . '/' . $mediaType['subtype'];
+        if (!empty($mediaType['params'])) {
+            foreach ($mediaType['params'] as $k => $v) {
+                $str .= '; ' . $k . '=' . $v;
+            }
+        }
+        return $str;
+    }
+}

plugins/ActivityPub/tests/Unit/ActivitypubProfileTest.php

@@ -0,0 +1,183 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+namespace Tests\Unit;
+
+use Tests\TestCase;
+
+class ProfileObjectTest extends TestCase
+{
+    public function testLibraryInstalled()
+    {
+        $this->assertTrue(class_exists('\Activitypub_profile'));
+    }
+
+    public function testActivitypubProfile()
+    {
+        // Mimic proper ACCEPT header
+        $_SERVER['HTTP_ACCEPT'] = 'application/ld+json; profile="https://www.w3.org/ns/activitystreams';
+
+        /* Test do_insert() */
+        $aprofile = new \Activitypub_profile();
+        $aprofile->uri = 'https://testinstance.net/index.php/user/1';
+        $aprofile->nickname = 'test1';
+        $aprofile->fullname = 'Test User 1';
+        $aprofile->bio      = 'I am a nice test 1 guy';
+        $aprofile->inboxuri = "https://testinstance.net/index.php/user/1/inbox.json";
+        $aprofile->sharedInboxuri = "https://testinstance.net/inbox.json";
+        $aprofile->do_insert();
+
+        /* Test local_profile() */
+        $profile = $aprofile->local_profile();
+
+        /* Test from_profile() and create_from_local_profile() */
+        $this->assertTrue($this->compare_aprofiles($aprofile, \Activitypub_profile::from_profile($profile)));
+
+        /* Create Keys for Test User 1 */
+        $apRSA = new \Activitypub_rsa();
+        $apRSA->profile_id = $profile->getID();
+        \Activitypub_rsa::generate_keys($apRSA->private_key, $apRSA->public_key);
+        $apRSA->store_keys();
+
+        /* Test profile_to_array() */
+        // Fetch ActivityPub Actor Object representation
+        $profile_array = \Activitypub_profile::profile_to_array($profile);
+        // Check type
+        $this->assertTrue(is_array($profile_array));
+        // Test with Explorer's Profile Tester
+        $this->assertTrue(\Activitypub_explorer::validate_remote_response($profile_array));
+
+        /* Test get_inbox() */
+        $this->assertTrue($aprofile->sharedInboxuri == $aprofile->get_inbox());
+
+        /* Test getUri() */
+        $this->assertTrue($aprofile->uri == $aprofile->getUri());
+
+        /* Test getUrl() */
+        $this->assertTrue($profile->getUrl() == $aprofile->getUrl());
+
+        /* Test getID() */
+        $this->assertTrue($profile->getID() == $aprofile->getID());
+
+        /* Test fromUri() */
+        $this->assertTrue($this->compare_aprofiles($aprofile, \Activitypub_profile::fromUri($aprofile->uri)));
+
+        /* Remove Remote User Test 1 */
+        $old_id = $profile->getID();
+        $apRSA->delete();
+        $aprofile->delete();
+        $profile->delete();
+        // Check if successfuly removed
+        try {
+            \Profile::getById($old_id);
+            $this->assertTrue(false);
+        } catch (\NoResultException $e) {
+            $this->assertTrue(true);
+        }
+
+        /* Test ensure_web_finger() */
+        // TODO: Maybe elaborate on this function's tests
+        try {
+            \Activitypub_profile::ensure_web_finger('test1@testinstance.net');
+            $this->assertTrue(false);
+        } catch (\Exception $e) {
+            $this->assertTrue($e->getMessage() == 'Not a valid webfinger address.' ||
+                              $e->getMessage() == 'Not a valid webfinger address (via cache).');
+        }
+    }
+
+    // Helpers
+
+    private function compare_profiles(\Profile $a, \Profile $b)
+    {
+        if (($av = $a->getID()) != ($bv = $b->getID())) {
+            throw new Exception('Compare Profiles 1 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->getNickname()) != ($bv = $b->getNickname())) {
+            throw new Exception('Compare Profiles 2 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->getFullname()) != ($bv = $b->getFullname())) {
+            throw new Exception('Compare Profiles 3 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->getUrl()) != ($bv = $b->getUrl())) {
+            throw new Exception('Compare Profiles 4 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->getDescription()) != ($bv = $b->getDescription())) {
+            throw new Exception('Compare Profiles 5 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->getLocation()) != ($bv = $b->getLocation())) {
+            throw new Exception('Compare Profiles 6 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->getNickname()) != ($bv = $b->getNickname())) {
+            throw new Exception('Compare Profiles 7 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->lat) != ($bv = $b->lat)) {
+            throw new Exception('Compare Profiles 8 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->lon) != ($bv = $b->lon)) {
+            throw new Exception('Compare Profiles 9 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        return true;
+    }
+
+    private function compare_aprofiles(\Activitypub_profile $a, \Activitypub_profile $b)
+    {
+        if (($av = $a->getUri()) != ($bv = $b->getUri())) {
+            throw new Exception('Compare AProfiles 1 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->getUrl()) != ($bv = $b->getUrl())) {
+            throw new Exception('Compare AProfiles 2 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->getID()) != ($bv = $b->getID())) {
+            throw new Exception('Compare AProfiles 3 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->profile_id) != ($bv = $b->profile_id)) {
+            throw new Exception('Compare AProfiles 4 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->inboxuri) != ($bv = $b->inboxuri)) {
+            throw new Exception('Compare AProfiles 5 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        if (($av = $a->sharedInboxuri) != ($bv = $b->sharedInboxuri)) {
+            throw new Exception('Compare AProfiles 6 Fail: $a: '.$av.' is different from $b: '.$bv);
+        }
+
+        return true;
+    }
+}

plugins/ActivityPub/tests/Unit/ExampleTest.php

@@ -0,0 +1,42 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+namespace Tests\Unit;
+
+use Tests\TestCase;
+
+class ExampleTest extends TestCase
+{
+    /**
+     * A basic test example.
+     *
+     * @return void
+     */
+    public function testBasicTest()
+    {
+        $this->assertTrue(true);
+    }
+}

plugins/ActivityPub/tests/Unit/HTTPSignatureTest.php

@@ -0,0 +1,165 @@
+<?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 2018-2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ * @link      http://www.gnu.org/software/social/
+ */
+
+namespace Tests\Unit;
+
+use Tests\TestCase;
+use GuzzleHttp\Client;
+use GuzzleHttp\Handler\CurlHandler;
+use GuzzleHttp\Handler\MockHandler;
+use GuzzleHttp\HandlerStack;
+use GuzzleHttp\Middleware;
+use GuzzleHttp\Psr7\Request;
+use GuzzleHttp\Psr7\Response;
+use HttpSignatures\Context;
+use HttpSignatures\GuzzleHttpSignatures;
+
+class HTTPSignatureTest extends TestCase
+{
+    /**
+     * @var Context
+     */
+    private $context;
+    /**
+     * @var Client
+     */
+    private $client;
+    /**
+     * @var
+     */
+    private $history = [];
+
+    public function testLibraryInstalled()
+    {
+        $this->assertTrue(class_exists('\GuzzleHttp\Client'));
+        $this->assertTrue(class_exists('\HttpSignatures\Context'));
+        $this->assertTrue(class_exists('\HttpSignatures\GuzzleHttpSignatures'));
+    }
+
+    public function setUp()
+    {
+        $this->context = new Context([
+            'keys' => ['pda' => 'secret'],
+            'algorithm' => 'hmac-sha256',
+            'headers' => ['(request-target)', 'date'],
+        ]);
+        $stack = new HandlerStack();
+        $stack->setHandler(new MockHandler([
+            new Response(200, ['Content-Length' => 0]),
+        ]));
+        $stack->push(GuzzleHttpSignatures::middlewareFromContext($this->context));
+        $stack->push(Middleware::history($this->history));
+        $this->client = new Client(['handler' => $stack]);
+    }
+    /**
+     * test signing a message
+     */
+    public function testGuzzleRequestHasExpectedHeaders()
+    {
+        $this->client->get('/path?query=123', [
+            'headers' => ['date' => 'today', 'accept' => 'llamas']
+        ]);
+        // get last request
+        $message = end($this->history);
+        /** @var Request $request */
+        $request = $message['request'];
+        /** @var Response $response */
+        $response = $message['request'];
+        $expectedString = implode(
+            ',',
+            [
+                'keyId="pda"',
+                'algorithm="hmac-sha256"',
+                'headers="(request-target) date"',
+                'signature="SFlytCGpsqb/9qYaKCQklGDvwgmrwfIERFnwt+yqPJw="',
+            ]
+        );
+        $this->assertEquals(
+            [$expectedString],
+            $request->getHeader('Signature')
+        );
+        $this->assertEquals(
+            ['Signature ' . $expectedString],
+            $request->getHeader('Authorization')
+        );
+    }
+    /**
+     * test signing a message with a URL that doesn't contain a ?query
+     */
+    public function testGuzzleRequestHasExpectedHeaders2()
+    {
+        $this->client->get('/path', [
+            'headers' => ['date' => 'today', 'accept' => 'llamas']
+        ]);
+        // get last request
+        $message = end($this->history);
+        /** @var Request $request */
+        $request = $message['request'];
+        /** @var Response $response */
+        $response = $message['request'];
+        $expectedString = implode(
+            ',',
+            [
+                'keyId="pda"',
+                'algorithm="hmac-sha256"',
+                'headers="(request-target) date"',
+                'signature="DAtF133khP05pS5Gh8f+zF/UF7mVUojMj7iJZO3Xk4o="',
+            ]
+        );
+        $this->assertEquals(
+            [$expectedString],
+            $request->getHeader('Signature')
+        );
+        $this->assertEquals(
+            ['Signature ' . $expectedString],
+            $request->getHeader('Authorization')
+        );
+    }
+    public function getVerifyGuzzleRequestVectors()
+    {
+        return [
+            /* path, headers */
+            ['/path?query=123', ['date' => 'today', 'accept' => 'llamas']],
+            ['/path?z=zebra&a=antelope', ['date' => 'today']],
+        ];
+    }
+    /**
+     * @dataProvider getVerifyGuzzleRequestVectors
+     * @param string $path
+     * @param array $headers
+     */
+    public function testVerifyGuzzleRequest($path, $headers)
+    {
+        $this->client->get($path, ['headers' => $headers]);
+        // get last request
+        $message = end($this->history);
+        /** @var Request $request */
+        $request = $message['request'];
+        /** @var Response $response */
+        $response = $message['request'];
+        $this->assertTrue($this->context->verifier()->isValid($request));
+    }
+}