Revert MediaProxy Host header validation

Something is going wrong here even though the tests are correct.

changelog.d/3896.add

@@ -1 +1 @@
-Validate Host header for MediaProxy and Uploads and return a 302 if the base_url has changed
+Validate Host header for Uploads and return a 302 if the base_url has changed

lib/pleroma/web/media_proxy/media_proxy_controller.ex

@@ -12,7 +12,6 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
   alias Pleroma.Web.MediaProxy
   alias Plug.Conn
 
-  plug(:validate_host)
   plug(:sandbox)
 
   def remote(conn, %{"sig" => sig64, "url" => url64}) do
@@ -206,30 +205,6 @@ defp media_proxy_opts do
     Config.get([:media_proxy, :proxy_opts], [])
   end
 
-  defp validate_host(conn, _params) do
-    %{scheme: proxy_scheme, host: proxy_host, port: proxy_port} =
-      MediaProxy.base_url() |> URI.parse()
-
-    if match?(^proxy_host, conn.host) do
-      conn
-    else
-      redirect_url =
-        %URI{
-          scheme: proxy_scheme,
-          host: proxy_host,
-          port: proxy_port,
-          path: conn.request_path,
-          query: conn.query_string
-        }
-        |> URI.to_string()
-        |> String.trim_trailing("?")
-
-      conn
-      |> Phoenix.Controller.redirect(external: redirect_url)
-      |> halt()
-    end
-  end
-
   defp sandbox(conn, _params) do
     conn
     |> merge_resp_headers([{"content-security-policy", "sandbox;"}])

test/pleroma/web/media_proxy/media_proxy_controller_test.exs

@@ -54,35 +54,6 @@ test "it returns 403 for invalid signature", %{conn: conn, url: url} do
              } = get(conn, "/proxy/hhgfh/eeee/fff")
     end
 
-    test "it returns a 302 for invalid host", %{conn: conn} do
-      new_proxy_base = "http://mp.localhost/"
-
-      %{scheme: new_proxy_scheme, host: new_proxy_host, port: new_proxy_port} =
-        URI.parse(new_proxy_base)
-
-      clear_config([:media_proxy, :base_url], new_proxy_base)
-
-      proxy_url =
-        MediaProxy.encode_url("https://pleroma.social/logo.jpeg")
-        |> URI.parse()
-        |> Map.put(:host, "wronghost")
-        |> URI.to_string()
-
-      expected_url =
-        URI.parse(proxy_url)
-        |> Map.put(:host, new_proxy_host)
-        |> Map.put(:port, new_proxy_port)
-        |> Map.put(:scheme, new_proxy_scheme)
-        |> URI.to_string()
-
-      with_mock Pleroma.ReverseProxy,
-        call: fn _conn, _url, _opts -> %Conn{status: :success} end do
-        conn = get(conn, proxy_url)
-
-        assert redirected_to(conn, 302) == expected_url
-      end
-    end
-
     test "redirects to valid url when filename is invalidated", %{conn: conn, url: url} do
       invalid_url = String.replace(url, "test.png", "test-file.png")
       response = get(conn, invalid_url)

test/support/conn_case.ex

@@ -120,9 +120,6 @@ defp json_response_and_validate_schema(conn, _status) do
 
     Mox.verify_on_exit!()
 
-    {:ok,
-     conn:
-       Phoenix.ConnTest.build_conn()
-       |> Map.put(:host, Pleroma.Web.Endpoint.host())}
+    {:ok, conn: Phoenix.ConnTest.build_conn()}
   end
 end