From 786173d270ec97318c74c658f82cc92ab49dff79 Mon Sep 17 00:00:00 2001
From: Ryan Barrett <git@ryanb.org>
Date: Mon, 23 Oct 2017 21:49:43 -0700
Subject: [PATCH] activitypub: point actor ids to bridgy fed, not source web
 site

...since we want to serve them as AS2.

for tootsuite/mastodon#5500
---
 appengine_config.py      |  5 +++++
 common.py                | 45 +++++++++++++++++++++++++++++-----------
 test/test_activitypub.py |  4 ++--
 test/test_webmention.py  |  3 +++
 4 files changed, 43 insertions(+), 14 deletions(-)

diff --git a/appengine_config.py b/appengine_config.py
index 430cf460..6d686139 100644
--- a/appengine_config.py
+++ b/appengine_config.py
@@ -13,6 +13,11 @@ except ValueError as e:
 
 from granary.appengine_config import *
 
+
+if os.environ.get('SERVER_SOFTWARE', '').startswith('Google App Engine/'):
+  HOST = 'fed.brid.gy'
+  HOST_URL = '%s://%s' % (SCHEME, HOST)
+
 # Make requests and urllib3 play nice with App Engine.
 # https://github.com/snarfed/bridgy/issues/396
 # http://stackoverflow.com/questions/34574740
diff --git a/common.py b/common.py
index f827c49d..7c6aba0c 100644
--- a/common.py
+++ b/common.py
@@ -10,11 +10,12 @@ import urlparse
 
 from bs4 import BeautifulSoup
 from granary import as2
-from oauth_dropins.webutil import util
+from oauth_dropins.webutil import handlers, util
 import requests
 from webmentiontools import send
 from webob import exc
 
+import appengine_config
 from models import Response
 
 DOMAIN_RE = r'([^/]+\.[^/]+)'
@@ -56,6 +57,8 @@ SUPPORTED_VERBS = (
     'update',
 )
 
+canonicalize_domain = handlers.redirect('bridgy-federated.appspot.com', 'fed.brid.gy')
+
 
 def requests_get(url, **kwargs):
     return _requests_fn(util.requests_get, url, **kwargs)
@@ -218,18 +221,22 @@ def postprocess_as2(activity, target=None, key=None):
       key: MagicKey, optional. populated into publicKey field if provided.
     """
     type = activity.get('type')
-    if type == 'Person' and not activity.get('publicKey'):
-        # underspecified, inferred from this issue and Mastodon's implementation:
-        # https://github.com/w3c/activitypub/issues/203#issuecomment-297553229
-        # https://github.com/tootsuite/mastodon/blob/bc2c263504e584e154384ecc2d804aeb1afb1ba3/app/services/activitypub/process_account_service.rb#L77
-        activity['publicKey'] = {
-            'publicKeyPem': key.public_pem(),
-        }
+
+    # actor objects
     if type == 'Person':
-        activity.setdefault('preferredUsername', USERNAME)
-    attr = activity.get('attributedTo')
-    if attr:
-        attr[0].setdefault('preferredUsername', USERNAME)
+        postprocess_as2_actor(activity)
+        if not activity.get('publicKey'):
+            # underspecified, inferred from this issue and Mastodon's implementation:
+            # https://github.com/w3c/activitypub/issues/203#issuecomment-297553229
+            # https://github.com/tootsuite/mastodon/blob/bc2c263504e584e154384ecc2d804aeb1afb1ba3/app/services/activitypub/process_account_service.rb#L77
+            activity['publicKey'] = {
+                'publicKeyPem': key.public_pem(),
+            }
+        return activity
+
+    for actor in (util.get_list(activity, 'attributedTo') +
+                  util.get_list(activity, 'actor')):
+        postprocess_as2_actor(actor)
 
     # inReplyTo: singly valued, prefer id over url
     target_id = target.get('id') if target else None
@@ -269,3 +276,17 @@ def postprocess_as2(activity, target=None, key=None):
         }
 
     return util.trim_nulls(activity)
+
+
+def postprocess_as2_actor(actor):
+    """Prepare an AS2 actor object to be served or sent via ActivityPub.
+
+    Args:
+      actor: dict, AS2 actor object
+    """
+    actor.setdefault('preferredUsername', USERNAME)
+
+    url = actor.get('url')
+    if url:
+        actor['id'] = '%s/%s' % (appengine_config.HOST_URL,
+                                 urlparse.urlparse(url).netloc)
diff --git a/test/test_activitypub.py b/test/test_activitypub.py
index f17680cc..ec642800 100644
--- a/test/test_activitypub.py
+++ b/test/test_activitypub.py
@@ -27,7 +27,7 @@ class ActivityPubTest(testutil.TestCase):
     def test_actor_handler(self, mock_get, _):
         mock_get.return_value = requests_response("""
 <body>
-<a class="h-card" rel="me" href="/about-me">Mrs. ☕ Foo</a>
+<a class="h-card u-url" rel="me" href="/about-me">Mrs. ☕ Foo</a>
 </body>
 """, url='https://foo.com/')
 
@@ -41,7 +41,7 @@ class ActivityPubTest(testutil.TestCase):
             'type' : 'Person',
             'name': 'Mrs. ☕ Foo',
             'preferredUsername': 'me',
-            'id': 'https://foo.com/about-me',
+            'id': 'http://localhost/foo.com',
             'url': 'https://foo.com/about-me',
             'inbox': 'http://localhost/foo.com/inbox',
             'publicKey': {
diff --git a/test/test_webmention.py b/test/test_webmention.py
index 7e690058..21f5781f 100644
--- a/test/test_webmention.py
+++ b/test/test_webmention.py
@@ -117,8 +117,10 @@ class WebmentionTest(testutil.TestCase):
             'cc': [AS2_PUBLIC_AUDIENCE, 'tag:orig,2017:as2'],
             'actor': {
                 'type': 'Person',
+                'id': 'http://localhost/orig',
                 'url': 'http://orig',
                 'name': 'Ms. ☕ Baz',
+                'preferredUsername': 'me',
             },
         }
 
@@ -161,6 +163,7 @@ class WebmentionTest(testutil.TestCase):
                 ],
                 'attributedTo': [{
                     'type': 'Person',
+                    'id': 'http://localhost/orig',
                     'url': 'http://orig',
                     'preferredUsername': 'me',
                     'name': 'Ms. ☕ Baz',