Permit Mastodon's weird HTML through

activities/admin.py

@@ -7,6 +7,12 @@ from activities.models import FanOut, Post, PostInteraction, TimelineEvent
 class PostAdmin(admin.ModelAdmin):
     list_display = ["id", "state", "author", "created"]
     raw_id_fields = ["to", "mentions"]
+    actions = ["force_fetch"]
+
+    @admin.action(description="Force Fetch")
+    def force_fetch(self, request, queryset):
+        for instance in queryset:
+            instance.debug_fetch()
 
 
 @admin.register(TimelineEvent)

activities/models/post.py

@@ -274,3 +274,18 @@ class Post(StatorModel):
             TimelineEvent.add_post(follow.source, post)
         # Force it into fanned_out as it's not ours
         post.transition_perform(PostStates.fanned_out)
+
+    def debug_fetch(self):
+        """
+        Fetches the Post from its original URL again and updates us with it
+        """
+        response = httpx.get(
+            self.object_uri,
+            headers={"Accept": "application/json"},
+            follow_redirects=True,
+        )
+        if 200 <= response.status_code < 300:
+            return self.by_ap(
+                canonicalise(response.json(), include_security=True),
+                update=True,
+            )

core/html.py

@@ -1,11 +1,31 @@
 import bleach
+from bleach.linkifier import LinkifyFilter
 from django.utils.safestring import mark_safe
 
 
+def allow_a(tag: str, name: str, value: str):
+    if name in ["href", "title", "class"]:
+        return True
+    elif name == "rel":
+        # Only allow rel attributes with a small subset of values
+        # (we're defending against, for example, rel=me)
+        rel_values = value.split()
+        if all(v in ["nofollow", "noopener", "noreferrer", "tag"] for v in rel_values):
+            return True
+    return False
+
+
 def sanitize_post(post_html: str) -> str:
     """
     Only allows a, br, p and span tags, and class attributes.
     """
-    return mark_safe(
+    cleaner = bleach.Cleaner(
-        bleach.clean(post_html, tags=["a", "br", "p", "span"], attributes=["class"])
+        tags=["a", "br", "p", "span"],
+        attributes={  # type:ignore
+            "a": allow_a,
+            "p": ["class"],
+            "span": ["class"],
+        },
+        filters=[LinkifyFilter],
     )
+    return mark_safe(cleaner.clean(post_html))

templates/activities/_post.html

@@ -1,6 +1,6 @@
 {% load static %}
 {% load activity_tags %}
-<div class="post">
+<div class="post" data-takahe-id="{{ post.id }}">
 
     {% if post.author.icon_uri %}
         <img src="{{post.author.icon_uri}}" class="icon">

users/views/activitypub.py

@@ -118,7 +118,7 @@ class Inbox(View):
             # See if we can fetch it right now
             async_to_sync(identity.fetch_actor)()
         if not identity.public_key:
-            print("Cannot get actor")
+            print("Cannot get actor", document["actor"])
             return HttpResponseBadRequest("Cannot retrieve actor")
         # If there's a "signature" payload, verify against that
         if "signature" in document: