From 95089c0c6179c9eed6cc05379514cfb7047477fa Mon Sep 17 00:00:00 2001
From: Andrew Godwin <andrew@aeracode.org>
Date: Sun, 12 Nov 2023 12:09:09 -0700
Subject: [PATCH] Ignore some messages at inbox view time

---
 tests/users/views/test_activitypub.py | 53 ++++++++++++++++++++++++++-
 users/views/activitypub.py            | 14 ++++++-
 2 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/tests/users/views/test_activitypub.py b/tests/users/views/test_activitypub.py
index c811e52..beb8642 100644
--- a/tests/users/views/test_activitypub.py
+++ b/tests/users/views/test_activitypub.py
@@ -1,5 +1,7 @@
 import pytest
 
+from users.models import InboxMessage
+
 
 @pytest.mark.django_db
 def test_webfinger_actor(client, identity):
@@ -59,5 +61,54 @@ def test_delete_unknown_actor(client, identity):
     resp = client.post(
         identity.inbox_uri, data=data, content_type="application/activity+json"
     )
-    print(resp.content)
+    assert resp.status_code == 202
+
+
+@pytest.mark.django_db
+def test_ignore_lemmy(client, identity):
+    """
+    Tests that message types we know we cannot handle are ignored immediately
+    """
+    data = {
+        "cc": "https://lemmy.ml/c/asklemmy/followers",
+        "id": "https://lemmy.ml/activities/announce/12345",
+        "to": "as:Public",
+        "type": "Announce",
+        "actor": "https://lemmy.ml/c/asklemmy",
+        "object": {
+            "id": "https://lemmy.world/activities/like/12345",
+            "type": "Like",
+            "actor": "https://lemmy.world/u/Nobody",
+            "object": "https://sopuli.xyz/comment/12345",
+            "audience": "https://lemmy.ml/c/asklemmy",
+        },
+        "@context": [
+            "https://www.w3.org/ns/activitystreams",
+            "https://w3id.org/security/v1",
+            {
+                "pt": "https://joinpeertube.org/ns#",
+                "sc": "http://schema.org/",
+                "lemmy": "https://join-lemmy.org/ns#",
+                "expires": "as:endTime",
+                "litepub": "http://litepub.social/ns#",
+                "language": "sc:inLanguage",
+                "stickied": "lemmy:stickied",
+                "sensitive": "as:sensitive",
+                "identifier": "sc:identifier",
+                "moderators": {"@id": "lemmy:moderators", "@type": "@id"},
+                "removeData": "lemmy:removeData",
+                "ChatMessage": "litepub:ChatMessage",
+                "matrixUserId": "lemmy:matrixUserId",
+                "distinguished": "lemmy:distinguished",
+                "commentsEnabled": "pt:commentsEnabled",
+                "postingRestrictedToMods": "lemmy:postingRestrictedToMods",
+            },
+            "https://w3id.org/security/v1",
+        ],
+    }
+    num_inbox_messages = InboxMessage.objects.count()
+    resp = client.post(
+        identity.inbox_uri, data=data, content_type="application/activity+json"
+    )
+    assert num_inbox_messages == InboxMessage.objects.count()
     assert resp.status_code == 202
diff --git a/users/views/activitypub.py b/users/views/activitypub.py
index 2408bb8..effbf5b 100644
--- a/users/views/activitypub.py
+++ b/users/views/activitypub.py
@@ -138,6 +138,11 @@ class Inbox(View):
             return HttpResponseBadRequest("Payload size too large")
         # Load the LD
         document = canonicalise(json.loads(request.body), include_security=True)
+        document_type = document["type"]
+        document_subtype = None
+        if isinstance(document.get("object"), dict):
+            document_subtype = document["object"].get("type")
+
         # Find the Identity by the actor on the incoming item
         # This ensures that the signature used for the headers matches the actor
         # described in the payload.
@@ -147,7 +152,7 @@ class Inbox(View):
 
         identity = Identity.by_actor_uri(document["actor"], create=True, transient=True)
         if (
-            document["type"] == "Delete"
+            document_type == "Delete"
             and document["actor"] == document["object"]
             and identity._state.adding
         ):
@@ -169,6 +174,11 @@ class Inbox(View):
             )
             return HttpResponse(status=202)
 
+        # See if it's a type of message we know we want to ignore right now
+        # (e.g. Lemmy likes/dislikes, which we can't process anyway)
+        if document_type == "Announce" and document_subtype in ["Like", "Dislike"]:
+            return HttpResponse(status=202)
+
         # authenticate HTTP signature first, if one is present and the actor
         # is already known to us. An invalid signature is an error and message
         # should be discarded. NOTE: for previously unknown actors, we
@@ -182,7 +192,7 @@ class Inbox(View):
                     )
                     logging.debug(
                         "Inbox: %s from %s has good HTTP signature",
-                        document["type"],
+                        document_type,
                         identity,
                     )
                 else: