[#2497] Configurability of :min_content_length (preview proxy). Refactoring, documentation, tests.

lib/pleroma/helpers/media_helper.ex

@@ -58,6 +58,7 @@ defmodule Pleroma.Helpers.MediaHelper do
 
   defp prepare_image_resize_args(_), do: {:error, :missing_options}
 
+  # Note: video thumbnail is intentionally not resized (always has original dimensions)
   def video_framegrab(url) do
     with executable when is_binary(executable) <- System.find_executable("ffmpeg"),
          {:ok, env} <- HTTP.get(url, [], pool: :media),

lib/pleroma/web/media_proxy/media_proxy_controller.ex

@@ -12,8 +12,6 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
   alias Pleroma.Web.MediaProxy
   alias Plug.Conn
 
-  @min_content_length_for_preview 100 * 1024
-
   def remote(conn, %{"sig" => sig64, "url" => url64}) do
     with {_, true} <- {:enabled, MediaProxy.enabled?()},
          {:ok, url} <- MediaProxy.decode_url(sig64, url64),
@@ -37,7 +35,8 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
 
   def preview(%Conn{} = conn, %{"sig" => sig64, "url" => url64}) do
     with {_, true} <- {:enabled, MediaProxy.preview_enabled?()},
-         {:ok, url} <- MediaProxy.decode_url(sig64, url64) do
+         {:ok, url} <- MediaProxy.decode_url(sig64, url64),
+         :ok <- MediaProxy.verify_request_path_and_url(conn, url) do
       handle_preview(conn, url)
     else
       {:enabled, false} ->
@@ -59,8 +58,25 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
       content_type = Tesla.get_header(head_response, "content-type")
       content_length = Tesla.get_header(head_response, "content-length")
       content_length = content_length && String.to_integer(content_length)
+      static = conn.params["static"] in ["true", true]
 
-      handle_preview(content_type, content_length, conn, media_proxy_url)
+      cond do
+        static and content_type == "image/gif" ->
+          handle_jpeg_preview(conn, media_proxy_url)
+
+        static ->
+          drop_static_param_and_redirect(conn)
+
+        content_type == "image/gif" ->
+          redirect(conn, external: media_proxy_url)
+
+        min_content_length_for_preview() > 0 and content_length > 0 and
+            content_length < min_content_length_for_preview() ->
+          redirect(conn, external: media_proxy_url)
+
+        true ->
+          handle_preview(content_type, conn, media_proxy_url)
+      end
     else
       # If HEAD failed, redirecting to media proxy URI doesn't make much sense; returning an error
       {_, %{status: status}} ->
@@ -74,58 +90,27 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
     end
   end
 
-  defp handle_preview(
-         "image/gif" = _content_type,
-         _content_length,
-         %{params: %{"static" => static}} = conn,
-         media_proxy_url
-       )
-       when static in ["true", true] do
-    handle_jpeg_preview(conn, media_proxy_url)
-  end
-
-  defp handle_preview(
-         _content_type,
-         _content_length,
-         %{params: %{"static" => static}} = conn,
-         _media_proxy_url
-       )
-       when static in ["true", true] do
-    uri_without_static_param = UriHelper.modify_uri_params(current_url(conn), %{}, ["static"])
-    redirect(conn, external: uri_without_static_param)
-  end
-
-  defp handle_preview("image/gif" = _content_type, _content_length, conn, media_proxy_url) do
-    redirect(conn, external: media_proxy_url)
-  end
-
-  defp handle_preview("image/" <> _ = _content_type, content_length, conn, media_proxy_url)
-       when is_integer(content_length) and content_length > 0 and
-              content_length < @min_content_length_for_preview do
-    redirect(conn, external: media_proxy_url)
-  end
-
-  defp handle_preview("image/png" <> _ = _content_type, _content_length, conn, media_proxy_url) do
+  defp handle_preview("image/png" <> _ = _content_type, conn, media_proxy_url) do
     handle_png_preview(conn, media_proxy_url)
   end
 
-  defp handle_preview("image/" <> _ = _content_type, _content_length, conn, media_proxy_url) do
+  defp handle_preview("image/" <> _ = _content_type, conn, media_proxy_url) do
     handle_jpeg_preview(conn, media_proxy_url)
   end
 
-  defp handle_preview("video/" <> _ = _content_type, _content_length, conn, media_proxy_url) do
+  defp handle_preview("video/" <> _ = _content_type, conn, media_proxy_url) do
     handle_video_preview(conn, media_proxy_url)
   end
 
-  defp handle_preview(_unsupported_content_type, _content_length, conn, media_proxy_url) do
+  defp handle_preview(_unsupported_content_type, conn, media_proxy_url) do
     fallback_on_preview_error(conn, media_proxy_url)
   end
 
   defp handle_png_preview(conn, media_proxy_url) do
     quality = Config.get!([:media_preview_proxy, :image_quality])
+    {thumbnail_max_width, thumbnail_max_height} = thumbnail_max_dimensions()
 
-    with {thumbnail_max_width, thumbnail_max_height} <- thumbnail_max_dimensions(),
-         {:ok, thumbnail_binary} <-
+    with {:ok, thumbnail_binary} <-
            MediaHelper.image_resize(
              media_proxy_url,
              %{
@@ -146,9 +131,9 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
 
   defp handle_jpeg_preview(conn, media_proxy_url) do
     quality = Config.get!([:media_preview_proxy, :image_quality])
+    {thumbnail_max_width, thumbnail_max_height} = thumbnail_max_dimensions()
 
-    with {thumbnail_max_width, thumbnail_max_height} <- thumbnail_max_dimensions(),
-         {:ok, thumbnail_binary} <-
+    with {:ok, thumbnail_binary} <-
            MediaHelper.image_resize(
              media_proxy_url,
              %{max_width: thumbnail_max_width, max_height: thumbnail_max_height, quality: quality}
@@ -174,6 +159,15 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
     end
   end
 
+  defp drop_static_param_and_redirect(conn) do
+    uri_without_static_param =
+      conn
+      |> current_url()
+      |> UriHelper.modify_uri_params(%{}, ["static"])
+
+    redirect(conn, external: uri_without_static_param)
+  end
+
   defp fallback_on_preview_error(conn, media_proxy_url) do
     redirect(conn, external: media_proxy_url)
   end
@@ -189,7 +183,7 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
   end
 
   defp thumbnail_max_dimensions do
-    config = Config.get([:media_preview_proxy], [])
+    config = media_preview_proxy_config()
 
     thumbnail_max_width = Keyword.fetch!(config, :thumbnail_max_width)
     thumbnail_max_height = Keyword.fetch!(config, :thumbnail_max_height)
@@ -197,6 +191,14 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
     {thumbnail_max_width, thumbnail_max_height}
   end
 
+  defp min_content_length_for_preview do
+    Keyword.get(media_preview_proxy_config(), :min_content_length, 0)
+  end
+
+  defp media_preview_proxy_config do
+    Config.get!([:media_preview_proxy])
+  end
+
   defp media_proxy_opts do
     Config.get([:media_proxy, :proxy_opts], [])
   end