Update spoofed activity test

Turns out we already had a test for activities spoofed via upload due
to an exploit several years. Back then *oma did not verify content-type
at all and doing so was the only adopted countermeasure.
Even the added test sample though suffered from a mismatching id, yet
nobody seems to have thought it a good idea to tighten id checks, huh

Since we will add stricter id checks later, make id and URL match
and also add a testcase for no content type at all. The new section
will be expanded in subsequent commits.

test/pleroma/object/fetcher_test.exs

@@ -14,6 +14,17 @@ defmodule Pleroma.Object.FetcherTest do
   import Mock
   import Tesla.Mock
 
+  defp spoofed_object_with_ids(
+         id \\ "https://patch.cx/objects/spoof",
+         actor_id \\ "https://patch.cx/users/rin"
+       ) do
+    File.read!("test/fixtures/spoofed-object.json")
+    |> Jason.decode!()
+    |> Map.put("id", id)
+    |> Map.put("actor", actor_id)
+    |> Jason.encode!()
+  end
+
   setup do
     mock(fn
       %{method: :get, url: "https://mastodon.example.org/users/userisgone"} ->
@@ -22,15 +33,28 @@ defmodule Pleroma.Object.FetcherTest do
       %{method: :get, url: "https://mastodon.example.org/users/userisgone404"} ->
         %Tesla.Env{status: 404}
 
+      # Spoof: wrong Content-Type
       %{
         method: :get,
-        url:
-          "https://patch.cx/media/03ca3c8b4ac3ddd08bf0f84be7885f2f88de0f709112131a22d83650819e36c2.json"
+        url: "https://patch.cx/objects/spoof_content_type.json"
       } ->
         %Tesla.Env{
           status: 200,
+          url: "https://patch.cx/objects/spoof_content_type.json",
           headers: [{"content-type", "application/json"}],
-          body: File.read!("test/fixtures/spoofed-object.json")
+          body: spoofed_object_with_ids("https://patch.cx/objects/spoof_content_type.json")
+        }
+
+      # Spoof: no Content-Type
+      %{
+        method: :get,
+        url: "https://patch.cx/objects/spoof_content_type"
+      } ->
+        %Tesla.Env{
+          status: 200,
+          url: "https://patch.cx/objects/spoof_content_type",
+          headers: [],
+          body: spoofed_object_with_ids("https://patch.cx/objects/spoof_content_type")
         }
 
       env ->
@@ -129,6 +153,22 @@ test "it rejects objects when attributedTo is wrong (variant 2)" do
     end
   end
 
+  describe "fetcher security and auth checks" do
+    test "it does not fetch a spoofed object without content type" do
+      assert {:error, {:content_type, nil}} =
+               Fetcher.fetch_and_contain_remote_object_from_id(
+                 "https://patch.cx/objects/spoof_content_type"
+               )
+    end
+
+    test "it does not fetch a spoofed object with wrong content type" do
+      assert {:error, {:content_type, _}} =
+               Fetcher.fetch_and_contain_remote_object_from_id(
+                 "https://patch.cx/objects/spoof_content_type.json"
+               )
+    end
+  end
+
   describe "fetching an object" do
     test "it fetches an object" do
       {:ok, object} =
@@ -155,13 +195,6 @@ test "Return MRF reason when fetched status is rejected by one" do
                )
     end
 
-    test "it does not fetch a spoofed object uploaded on an instance as an attachment" do
-      assert {:error, _} =
-               Fetcher.fetch_object_from_id(
-                 "https://patch.cx/media/03ca3c8b4ac3ddd08bf0f84be7885f2f88de0f709112131a22d83650819e36c2.json"
-               )
-    end
-
     test "does not fetch anything from a rejected instance" do
       clear_config([:mrf_simple, :reject], [{"evil.example.org", "i said so"}])