support GNU Social

[snarfed]

seems to be fully ostatus compatible, i just haven't gotten an end to end test all the way through in testing. next step for me is to add a PuSH hub to snarfed.org's atom, which is where it currently stops:

2017-09-11 14:09:12 LOG_DEBUG: [localhost:49561.bf2ad337 POST /main/salmon/user/1] Salmon envelope parsing failed with: FeedSubNoHubException
2017-09-11 14:09:12 LOG_DEBUG: [localhost:49561.bf2ad337 POST /main/salmon/user/1] action.php - User error '400' on 'usersalmon': FeedSubNoHubException
2017-09-11 14:09:12 LOG_ERR: [localhost:49561.bf2ad337 POST /main/salmon/user/1] Handled clientError (400) but cannot output into desired format (NULL): 'FeedSubNoHubException'

[snarfed]

Tried sending this like to https://gnusocial.net/notice/13746139 , got an ugly HTML 500 response to the AP inbox delivery request:

W 2023-01-17 03:32:16.995925+00:00
File "/layers/google.python.pip/pip/lib/python3.9/site-packages/oauth_dropins/webutil/util.py", line 1598, in call resp.raise_for_status()
File "/layers/google.python.pip/pip/lib/python3.9/site-packages/requests/models.py", line 1021, in raise_for_status raise HTTPError(http_error_msg, response=self)
E 2023-01-17 03:32:17.070592+00:00 : 502 Bad Gateway: 500 Server Error: Internal Server Error for url: https://gnusocial.net/user/1/inbox.json ;

Internal Server Error
Argument 1 passed to Activitypub_explorer::get_profile_from_url() must be of the type string, array given, called in /var/www/gnusocial/plugins/ActivityPub/actions/apinbox.php on line 68

AS2 object that was delivered to https://gnusocial.net/user/1/inbox.json:

{
  "published": "2023-01-16T19:32:08-08:00",
  "content": "likes <a class=\"u-like u-like-of\" href=\"https://gnusocial.net/notice/13746139\">admin de [gnusocial.net](http://gnusocial.net/) (administrator@[gnusocial.net](http://gnusocial.net/))\u2019s status on Sunday, 15-Jan-2023 17:44:44 CET \u2013 [gnusocial.net](http://gnusocial.net/)</a>",
  "url": "https://fed.brid.gy/r/https://snarfed.org/2023-01-16_admin-de-gnusocial-nets-status-on-sunday-15-jan-2023-174444-cet",
  "actor": {
    "url": "https://fed.brid.gy/r/https://snarfed.org/",
    "image": {
      "url": "https://secure.gravatar.com/avatar/947b5f3f323da0ef785b6f02d9c265d6?s=96&d=blank&r=g",
      "type": "Image"
    },
    "type": "Person",
    "name": "Ryan Barrett",
    "icon": {
      "url": "https://secure.gravatar.com/avatar/947b5f3f323da0ef785b6f02d9c265d6?s=96&d=blank&r=g",
      "type": "Image"
    },
    "id": "https://fed.brid.gy/snarfed.org",
    "preferredUsername": "[snarfed.org](http://snarfed.org/)"
  },
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Like",
  "object": "https://gnusocial.net/object/note/13746139",
  "id": "https://fed.brid.gy/r/https://snarfed.org/2023-01-16_admin-de-gnusocial-nets-status-on-sunday-15-jan-2023-174444-cet",
  "cc": [
    "https://gnusocial.net/index.php/user/1",
    "https://www.w3.org/ns/activitystreams#Public",
    "https://gnusocial.net/index.php/user/404464",
    "https://gnusocial.net/user/1/followers.json"
  ],
  "to": [
    "https://www.w3.org/ns/activitystreams#Public"
  ]
}

[snarfed]

gnusocial.net instance details are https://gnusocial.net/doc/about, but I couldn't find the version it's running. GNU Social site is https://www.gnusocial.rocks/, mailing list is https://lists.gnu.org/archive/html/social-discuss/, repo and bug tracker is at https://notabug.org/diogo/gnu-social/issues. I went there to report a bug, but that part of the site is down, and the rest is slow and barely loads either. Ah well.