From d7642e03923d42f95f4a54463dc578f2a74a075d Mon Sep 17 00:00:00 2001
From: Ryan Barrett <git@ryanb.org>
Date: Sat, 17 Aug 2024 16:48:55 -0700
Subject: [PATCH] AP DMs: wrap in post activity, add mention tag, improve DM vs
 public handling

---
 activitypub.py             | 14 ++++++++------
 protocol.py                |  4 ++++
 tests/test_activitypub.py  | 37 ++++++++++++++++++++++++++++++++++++-
 tests/test_integrations.py |  6 +++++-
 4 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/activitypub.py b/activitypub.py
index 9cab442..df48453 100644
--- a/activitypub.py
+++ b/activitypub.py
@@ -785,7 +785,9 @@ def postprocess_as2(activity, orig_obj=None, wrap=True):
     tags = util.get_list(activity, 'tag') + util.get_list(obj, 'tag')
     for tag in tags:
         href = tag.get('href')
-        if (href and tag.get('type') == 'Mention'
+        if (tag.get('type') == 'Mention'
+                and href
+                and href not in util.get_list(obj_or_activity, 'to')
                 and not ActivityPub.is_blocklisted(href)):
             add(cc, href)
 
@@ -794,15 +796,15 @@ def postprocess_as2(activity, orig_obj=None, wrap=True):
             for recip in as1.get_objects(orig_obj, field):
                 add(cc, util.get_url(recip) or recip.get('id'))
 
-    # ideally I'd use as1.is_dm here, but it's for AS1, not AS2
-    to = activity.setdefault('to', [])
-    is_dm = not cc and len(to) == 1
-    if not is_dm:
+    # WARNING: activity here is AS2, but we're using as1.is_dm. right now the
+    # logic is effectively the same for our purposes, but watch out here if that
+    # ever changes.
+    if not as1.is_dm(activity):
         # to public, since Mastodon interprets to public as public, cc public as
         # unlisted:
         # https://socialhub.activitypub.rocks/t/visibility-to-cc-mapping/284
         # https://wordsmith.social/falkreon/securing-activitypub
-        add(to, as2.PUBLIC_AUDIENCE)
+        add(activity.setdefault('to', []), as2.PUBLIC_AUDIENCE)
 
     # hashtags. Mastodon requires:
     # * type: Hashtag
diff --git a/protocol.py b/protocol.py
index 5f987d5..cd5ef74 100644
--- a/protocol.py
+++ b/protocol.py
@@ -1174,6 +1174,10 @@ class Protocol:
                 'id': id,
                 'author': bot.key.id(),
                 'content': text,
+                'tags': [{
+                    'objectType': 'mention',
+                    'url': to_user.key.id(),
+                }],
                 'to': [to_user.key.id()],
             },
             'to': [to_user.key.id()],
diff --git a/tests/test_activitypub.py b/tests/test_activitypub.py
index 0d36c51..91ac8e5 100644
--- a/tests/test_activitypub.py
+++ b/tests/test_activitypub.py
@@ -2456,7 +2456,7 @@ class ActivityPubUtilsTest(TestCase):
         self.assertEqual(['https://masto.foo/@other'],
                          postprocess_as2(obj)['cc'])
 
-    def test_postprocess_as2_dm(self):
+    def test_postprocess_as2_dm_note(self):
         dm = {
             'objectType': 'note',
             'author': 'web.brid.gy',
@@ -2466,6 +2466,41 @@ class ActivityPubUtilsTest(TestCase):
         }
         self.assertEqual(dm, postprocess_as2(copy.deepcopy(dm)))
 
+    def test_postprocess_as2_dm_note_with_mention_tag(self):
+        dm = {
+            'objectType': 'note',
+            'author': 'web.brid.gy',
+            'content': '<p>hello world</p>',
+            'contentMap': {'en': '<p>hello world</p>'},
+            'tags': [{
+                'objectType': 'mention',
+                'url': 'https://inst/user',
+            }],
+            'to': ['http://inst/user'],
+        }
+        self.assertEqual(dm, postprocess_as2(copy.deepcopy(dm)))
+
+    def test_postprocess_as2_dm_create(self):
+        dm = {
+            'objectType': 'activity',
+            'verb': 'post',
+            'id': 'https://inst/dm#create',
+            'actor': 'web.brid.gy',
+            'object': {
+                'objectType': 'note',
+                'id': 'https://inst/dm',
+                'author': 'web.brid.gy',
+                'content': '<p>hello world</p>',
+                'contentMap': {'en': '<p>hello world</p>'},
+                'to': ['http://inst/user'],
+            },
+            'to': ['http://inst/user'],
+        }
+        self.assertEqual({
+            **dm,
+            'id': 'http://localhost/r/https://inst/dm#create',
+        }, postprocess_as2(copy.deepcopy(dm)))
+
     @patch('requests.get')
     def test_signed_get_redirects_manually_with_new_sig_headers(self, mock_get):
         mock_get.side_effect = [
diff --git a/tests/test_integrations.py b/tests/test_integrations.py
index 70dd13e..e95aaf7 100644
--- a/tests/test_integrations.py
+++ b/tests/test_integrations.py
@@ -409,10 +409,14 @@ class IntegrationTests(TestCase):
                 'content': message,
                 'contentMap': {'en': message},
                 'content_is_html': True,
+                'tag': [{
+                    'type': 'Mention',
+                    'href': 'https://inst/alice',
+                }],
                 'to': ['https://inst/alice'],
             },
             'to': ['https://inst/alice'],
-        }, json_loads(kwargs['data']), ignore=['to', '@context'])
+        }, json_loads(kwargs['data']), ignore=['@context'])
 
         # bot user follows back
         args, kwargs = mock_post.call_args_list[2]