From 9fe2e6676c32b93023ae301be587a8ab0d93120f Mon Sep 17 00:00:00 2001
From: Andrew Godwin
Date: Mon, 5 Dec 2022 20:02:35 -0700
Subject: Add a middleware to detect LD Accept headers

---
 activities/views/posts.py |  7 +------
 core/middleware.py        | 19 +++++++++++++++++++
 takahe/settings.py        |  1 +
 users/views/identity.py   |  7 +------
 4 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/activities/views/posts.py b/activities/views/posts.py
index 1962274..adc732c 100644
--- a/activities/views/posts.py
+++ b/activities/views/posts.py
@@ -21,12 +21,7 @@ class Individual(TemplateView):
         self.identity = by_handle_or_404(self.request, handle, local=False)
         self.post_obj = get_object_or_404(self.identity.posts, pk=post_id)
         # If they're coming in looking for JSON, they want the actor
-        accept = request.headers.get("accept", "text/html").lower()
-        if (
-            "application/json" in accept
-            or "application/ld" in accept
-            or "application/activity" in accept
-        ):
+        if request.ap_json:
             # Return post JSON
             return self.serve_object()
         else:
diff --git a/core/middleware.py b/core/middleware.py
index 274f672..de35c4c 100644
--- a/core/middleware.py
+++ b/core/middleware.py
@@ -6,6 +6,25 @@ from core import sentry
 from core.models import Config
 
 
+class AcceptMiddleware:
+    """
+    Detects any Accept headers signifying a fellow AP server is trying to get JSON.
+    """
+
+    def __init__(self, get_response):
+        self.get_response = get_response
+
+    def __call__(self, request):
+        accept = request.headers.get("accept", "text/html").lower()
+        request.ap_json = (
+            "application/json" in accept
+            or "application/ld" in accept
+            or "application/activity" in accept
+        )
+        response = self.get_response(request)
+        return response
+
+
 class ConfigLoadingMiddleware:
     """
     Caches the system config every request
diff --git a/takahe/settings.py b/takahe/settings.py
index d46ec73..f263153 100644
--- a/takahe/settings.py
+++ b/takahe/settings.py
@@ -178,6 +178,7 @@ MIDDLEWARE = [
     "django.contrib.messages.middleware.MessageMiddleware",
     "django.middleware.clickjacking.XFrameOptionsMiddleware",
     "django_htmx.middleware.HtmxMiddleware",
+    "core.middleware.AcceptMiddleware",
     "core.middleware.ConfigLoadingMiddleware",
     "users.middleware.IdentityMiddleware",
 ]
diff --git a/users/views/identity.py b/users/views/identity.py
index 27d2e4e..4996ad7 100644
--- a/users/views/identity.py
+++ b/users/views/identity.py
@@ -42,12 +42,7 @@ class ViewIdentity(ListView):
         ):
             self.identity.transition_perform(IdentityStates.outdated)
         # If they're coming in looking for JSON, they want the actor
-        accept = request.headers.get("accept", "text/html").lower()
-        if (
-            "application/json" in accept
-            or "application/ld" in accept
-            or "application/activity" in accept
-        ):
+        if request.ap_json:
             # Return actor info
             return self.serve_actor(self.identity)
         else:
-- 
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