ML-181: harden assets endpoints

test/music_library/assets/transform_test.exs

@@ -2,4 +2,52 @@ defmodule MusicLibrary.Assets.TransformTest do
   use ExUnit.Case, async: true
 
   doctest MusicLibrary.Assets.Transform
+
+  alias MusicLibrary.Assets.Transform
+
+  defp make_payload(params) do
+    params |> JSON.encode!() |> Base.url_encode64(padding: false)
+  end
+
+  describe "decode/1 width validation" do
+    test "rejects string width" do
+      payload = make_payload(%{hash: "abc", width: "300"})
+      assert {:error, :invalid_payload} = Transform.decode(payload)
+    end
+
+    test "rejects negative width" do
+      payload = make_payload(%{hash: "abc", width: -1})
+      assert {:error, :invalid_payload} = Transform.decode(payload)
+    end
+
+    test "rejects zero width" do
+      payload = make_payload(%{hash: "abc", width: 0})
+      assert {:error, :invalid_payload} = Transform.decode(payload)
+    end
+
+    test "rejects float width" do
+      payload = make_payload(%{hash: "abc", width: 300.5})
+      assert {:error, :invalid_payload} = Transform.decode(payload)
+    end
+
+    test "rejects very large width" do
+      payload = make_payload(%{hash: "abc", width: 99_999})
+      assert {:error, :invalid_payload} = Transform.decode(payload)
+    end
+
+    test "accepts nil width" do
+      payload = make_payload(%{hash: "abc", width: nil})
+      assert {:ok, %Transform{hash: "abc", width: nil}} = Transform.decode(payload)
+    end
+
+    test "accepts max allowed width 2048" do
+      payload = make_payload(%{hash: "abc", width: 2048})
+      assert {:ok, %Transform{hash: "abc", width: 2048}} = Transform.decode(payload)
+    end
+
+    test "accepts width 1" do
+      payload = make_payload(%{hash: "abc", width: 1})
+      assert {:ok, %Transform{hash: "abc", width: 1}} = Transform.decode(payload)
+    end
+  end
 end

test/music_library_web/controllers/asset_controller_test.exs

@@ -87,6 +87,67 @@ defmodule MusicLibraryWeb.AssetControllerTest do
       assert text_response(conn, 404) == "Not found"
     end
 
+    test "400s when payload has string width", %{conn: conn, asset: asset} do
+      payload =
+        %{hash: asset.hash, width: "300"}
+        |> JSON.encode!()
+        |> Base.url_encode64(padding: false)
+
+      conn = get(conn, ~p"/assets/#{payload}")
+      assert text_response(conn, 400) == "Bad request"
+    end
+
+    test "400s when payload has negative width", %{conn: conn, asset: asset} do
+      payload =
+        %{hash: asset.hash, width: -1}
+        |> JSON.encode!()
+        |> Base.url_encode64(padding: false)
+
+      conn = get(conn, ~p"/assets/#{payload}")
+      assert text_response(conn, 400) == "Bad request"
+    end
+
+    test "400s when payload has very large width", %{conn: conn, asset: asset} do
+      payload =
+        %{hash: asset.hash, width: 99_999}
+        |> JSON.encode!()
+        |> Base.url_encode64(padding: false)
+
+      conn = get(conn, ~p"/assets/#{payload}")
+      assert text_response(conn, 400) == "Bad request"
+    end
+
+    test "canonical cache key collapses variant payloads into single ETS entry", %{
+      conn: conn,
+      asset: asset
+    } do
+      # Two variant payloads encoding the same (hash, width)
+      payload_a =
+        %{hash: asset.hash, width: 480}
+        |> JSON.encode!()
+        |> Base.url_encode64(padding: false)
+
+      # Same hash/width but different JSON key order / whitespace
+      payload_b =
+        %{width: 480, hash: asset.hash}
+        |> JSON.encode!()
+        |> Base.url_encode64(padding: false)
+
+      # First request populates the cache
+      conn_a = get(conn, ~p"/assets/#{payload_a}")
+      assert conn_a.status == 200
+      assert get_resp_header(conn_a, "etag") == [payload_a]
+
+      # Second request with different payload but same canonical key
+      # should serve from cache (same content, correct ETag for this payload)
+      conn_b = get(conn, ~p"/assets/#{payload_b}")
+      assert conn_b.status == 200
+      assert get_resp_header(conn_b, "etag") == [payload_b]
+
+      # Both should return the same image content
+      assert conn_a.resp_body == conn_b.resp_body
+    end
+
     @tag :capture_log
     test "404s when asset content is corrupt", %{conn: conn} do
       {:ok, asset} = Assets.store(%{content: "not an image", format: "image/jpeg"})