incoming Follows: synthesize url into follow object stored in Activity

rendered mf2 HTML proxy pages (in render.py) fall back to redirecting to the follow's AS2 id field, but Mastodon's ids are URLs that don't load in browsers, eg https://jawns.club/ac33c547-ca6b-4351-80d5-d11a6879a7b0. so, set a synthetic URL based on the follower's profile. fixes #336

activitypub.py

@@ -157,10 +157,10 @@ def accept_follow(follow, follow_unwrapped, user):
 
     followee = follow.get('object')
     followee_unwrapped = follow_unwrapped.get('object')
-    if isinstance(followee_unwrapped, dict):
-        followee_unwrapped = followee_unwrapped.get('id')
+    followee_id = (followee_unwrapped.get('id')
+                   if isinstance(followee_unwrapped, dict) else followee_unwrapped)
     follower = follow.get('actor')
-    if not followee or not followee_unwrapped or not follower:
+    if not followee or not followee_id or not follower:
         error('Follow activity requires object and actor. Got: %s' % follow)
 
     inbox = follower.get('inbox')
@@ -168,8 +168,17 @@ def accept_follow(follow, follow_unwrapped, user):
     if not inbox or not follower_id:
         error('Follow actor requires id and inbox. Got: %s', follower)
 
+    # rendered mf2 HTML proxy pages (in render.py) fall back to redirecting to
+    # the follow's AS2 id field, but Mastodon's ids are URLs that don't load in
+    # browsers, eg https://jawns.club/ac33c547-ca6b-4351-80d5-d11a6879a7b0
+    # so, set a synthetic URL based on the follower's profile.
+    # https://github.com/snarfed/bridgy-fed/issues/336
+    follower_url = util.get_url(follower) or follower_id
+    followee_url = util.get_url(followee_unwrapped) or followee_id
+    follow_unwrapped.setdefault('url', f'{follower_url}#followed-{followee_url}')
+
     # store Follower
-    followee_domain = util.domain_from_link(followee_unwrapped, minimize=False)
+    followee_domain = util.domain_from_link(followee_id, minimize=False)
     # follow use_instead, if any
     followee_domain = User.get_or_create(followee_domain).key.id()
     follower = Follower.get_or_create(dest=followee_domain, src=follower_id,

models.py

@@ -292,7 +292,7 @@ class Activity(StringIdModel):
 
         actor = util.get_first(as1, 'actor') or util.get_first(as1, 'author') or {}
         if isinstance(actor, str):
-            return util.pretty_link(url)
+            return util.pretty_link(actor)
 
         url = util.get_first(actor, 'url') or ''
         name = actor.get('displayName') or ''

render.py

@@ -6,6 +6,7 @@ from flask import request
 from granary import as2, atom, microformats2
 from oauth_dropins.webutil import flask_util
 from oauth_dropins.webutil.flask_util import error
+from oauth_dropins.webutil import util
 from oauth_dropins.webutil.util import json_loads
 
 from app import app, cache
@@ -38,5 +39,6 @@ def render():
     # browsers but not for webmention receivers (hopefully).
     html = microformats2.activities_to_html([as1])
     utf8 = '<meta charset="utf-8">'
-    refresh = f'<meta http-equiv="refresh" content="0;url={source}">'
+    url = util.get_url(as1) or as1.get('id') or source
+    refresh = f'<meta http-equiv="refresh" content="0;url={url}">'
     return html.replace(utf8, utf8 + '\n' + refresh)

tests/test_activitypub.py

@@ -399,7 +399,10 @@ class ActivityPubTest(testutil.TestCase):
                                        mock_head, mock_get, mock_post)
 
         activity = Activity.query().get()
-        self.assertEqual(FOLLOW_WITH_ACTOR, json_loads(activity.source_as2))
+        follow = copy.deepcopy(FOLLOW_WITH_ACTOR)
+        follow['url'] = 'https://mastodon.social/users/swentel#followed-https://www.realize.be/'
+
+        self.assertEqual(follow, json_loads(activity.source_as2))
 
         follower = Follower.query().get()
         self.assertEqual(FOLLOW_WRAPPED_WITH_ACTOR, json_loads(follower.last_follow))
@@ -422,13 +425,6 @@ class ActivityPubTest(testutil.TestCase):
 
         self._test_inbox_follow_accept(follow, accept, mock_head, mock_get, mock_post)
 
-        activity = Activity.query().get()
-        follow.update({
-            'actor': FOLLOW_WITH_ACTOR['actor'],
-            'object': unwrapped_user,
-        })
-        self.assertEqual(follow, json_loads(activity.source_as2))
-
         follower = Follower.query().get()
         follow.update({
             'actor': ACTOR,
@@ -436,6 +432,14 @@ class ActivityPubTest(testutil.TestCase):
         })
         self.assertEqual(follow, json_loads(follower.last_follow))
 
+        activity = Activity.query().get()
+        follow.update({
+            'actor': FOLLOW_WITH_ACTOR['actor'],
+            'object': unwrapped_user,
+            'url': 'https://mastodon.social/users/swentel#followed-https://www.realize.be/',
+        })
+        self.assertEqual(follow, json_loads(activity.source_as2))
+
     def _test_inbox_follow_accept(self, follow_as2, accept_as2,
                                   mock_head, mock_get, mock_post):
         mock_head.return_value = requests_response(url='https://www.realize.be/')

tests/test_render.py

@@ -2,6 +2,7 @@
 """Unit tests for render.py."""
 from oauth_dropins.webutil.util import json_dumps
 
+import common
 from models import Activity
 import render
 from . import testutil
@@ -42,7 +43,7 @@ class RenderTest(testutil.TestCase):
 <!DOCTYPE html>
 <html>
 <head><meta charset="utf-8">
-<meta http-equiv="refresh" content="0;url=abc"></head>
+<meta http-equiv="refresh" content="0;url=http://this/reply"></head>
 <body class="">
 <article class="h-entry">
   <span class="p-uid">http://this/reply</span>