add AP sharedInbox

#285, https://www.w3.org/TR/activitypub/#sharedInbox

activitypub.py

@@ -100,6 +100,7 @@ def actor(domain):
     obj.update({
         'preferredUsername': domain,
         'inbox': f'{request.host_url}{domain}/inbox',
+        'sharedInbox': f'{request.host_url}inbox',
         'outbox': f'{request.host_url}{domain}/outbox',
         'following': f'{request.host_url}{domain}/following',
         'followers': f'{request.host_url}{domain}/followers',
@@ -112,9 +113,10 @@ def actor(domain):
     })
 
 
+@app.post(f'/inbox')
 @app.post(f'/<regex("{common.DOMAIN_RE}"):domain>/inbox')
 def inbox(domain):
-    """Accepts POSTs to /[DOMAIN]/inbox and converts to outbound webmentions."""
+    """Handles ActivityPub inbox delivery."""
     body = request.get_data(as_text=True)
     logger.info(f'Got: {body}')
 

models.py

@@ -43,7 +43,7 @@ class User(StringIdModel):
             # while depending on the amount of randomness available.
             pubexp, mod, privexp = magicsigs.generate()
             user = User(id=domain, mod=mod, public_exponent=pubexp,
-                           private_exponent=privexp)
+                        private_exponent=privexp)
             user.put()
 
         return user

tests/test_activitypub.py

@@ -174,6 +174,7 @@ class ActivityPubTest(testutil.TestCase):
             'id': 'http://localhost/foo.com',
             'url': 'http://localhost/r/https://foo.com/about-me',
             'inbox': 'http://localhost/foo.com/inbox',
+            'sharedInbox': 'http://localhost/inbox',
             'outbox': 'http://localhost/foo.com/outbox',
             'following': 'http://localhost/foo.com/following',
             'followers': 'http://localhost/foo.com/followers',

tests/test_webfinger.py

@@ -63,6 +63,10 @@ class WebfingerTest(testutil.TestCase):
                 'rel': 'inbox',
                 'type': 'application/activity+json',
                 'href': 'http://localhost/foo.com/inbox'
+            }, {
+                'rel': 'sharedInbox',
+                'type': 'application/activity+json',
+                'href': 'http://localhost/inbox'
             }, {
                 'rel': 'http://schemas.google.com/g/2010#updates-from',
                 'type': 'application/atom+xml',

webfinger.py

@@ -123,6 +123,13 @@ class Actor(flask_util.XrdOrJrd):
                 'rel': 'inbox',
                 'type': common.CONTENT_TYPE_AS2,
                 'href': f'{request.host_url}{domain}/inbox',
+            }, {
+                # AP reads this from the AS2 actor, not webfinger, so strictly
+                # speaking, it's probably not needed here.
+                # https://www.w3.org/TR/activitypub/#sharedInbox
+                'rel': 'sharedInbox',
+                'type': common.CONTENT_TYPE_AS2,
+                'href': f'{request.host_url}inbox',
             },
 
             # OStatus