[WIP] set up streaming route

.sobelow-conf

@@ -9,7 +9,15 @@
   threshold: :low,
   # All of these are ignorable because this app is intended to be single-user and self-hosted.
   # There is an expectation that the user won't intentionally run a FS Traversal on themselves
-  ignore: ["CI.System", "Traversal.FileModule", "Config.HTTPS", "Config.CSP"],
+  ignore:
+    [
+      "CI.System",
+      "Traversal.FileModule",
+      "Config.HTTPS",
+      "Config.CSP",
+      "XSS.ContentType",
+      "Traversal.SendFile"
+    ],
   ignore_files: [],
   version: false
 ]

lib/pinchflat_web/controllers/media_items/media_item_controller.ex

@@ -29,4 +29,68 @@ defmodule PinchflatWeb.MediaItems.MediaItemController do
     |> put_flash(:info, flash_message)
     |> redirect(to: ~p"/sources/#{media_item.source_id}")
   end
+
+  # See here for details on streaming files and range requests:
+  # https://www.zeng.dev/post/2023-http-range-and-play-mp4-in-browser/
+  def stream(conn, %{"id" => id}) do
+    media_item = Media.get_media_item!(id)
+
+    # TODO: show audio vs. video element in UI depending on media type
+    # TODO: consider how a podcast RSS feed would interact with HTTP basic auth
+    # TODO: reconsider the sobelow changes I made
+    # TODO: UUID stuff
+
+    if File.exists?(media_item.media_filepath) do
+      file_size = File.stat!(media_item.media_filepath).size
+      mime_type = MIME.from_path(media_item.media_filepath)
+
+      case parse_range(conn, file_size) do
+        {:ok, {start_pos, end_pos}} ->
+          length = end_pos - start_pos + 1
+
+          conn
+          |> put_resp_content_type(mime_type)
+          |> put_resp_header("accept-ranges", "bytes")
+          |> put_resp_header("content-range", "bytes #{start_pos}-#{end_pos}/#{file_size}")
+          |> put_resp_header("content-length", to_string(length))
+          |> send_file(206, media_item.media_filepath, start_pos, length)
+
+        {:error, :invalid_range} ->
+          conn
+          |> put_resp_content_type(mime_type)
+          |> put_resp_header("content-length", to_string(file_size))
+          |> put_resp_header("accept-ranges", "bytes")
+          |> send_file(200, media_item.media_filepath)
+      end
+    else
+      send_resp(conn, 404, "File not found")
+    end
+  end
+
+  defp parse_range(conn, file_size) do
+    with [range_header | _] <- get_req_header(conn, "range"),
+         ["bytes", range] <- String.split(range_header, "="),
+         [start_pos, end_pos] <- String.split(range, "-") do
+      validate_range(start_pos, end_pos, file_size)
+    else
+      _ -> {:error, :invalid_range}
+    end
+  end
+
+  defp validate_range(start_pos, end_pos, file_size) do
+    case {Integer.parse(start_pos), Integer.parse(end_pos)} do
+      {:error, :error} ->
+        {:error, :invalid_range}
+
+      {{start_pos, _}, :error} ->
+        {:ok, {start_pos, file_size - 1}}
+
+      # See RFC7233
+      {{start_pos, _}, {end_pos, _}} when end_pos >= file_size ->
+        {:ok, {start_pos, file_size - 1}}
+
+      {{start_pos, _}, {end_pos, _}} ->
+        {:ok, {start_pos, end_pos}}
+    end
+  end
 end

lib/pinchflat_web/controllers/media_items/media_item_html/show.html.heex

@@ -13,6 +13,14 @@
     <.tabbed_layout>
       <:tab title="Attributes">
         <div class="flex flex-col gap-10 dark:text-white">
+          <%!-- <audio controls class="w-full">
+            <source src={~p"/media/#{@media_item}/stream"} type="audio/mpeg" />
+            Your browser does not support the audio element.
+          </audio> --%>
+          <video controls class="w-full">
+            <source src={~p"/media/#{@media_item}/stream"} type="video/mp4" />
+            Your browser does not support the video element.
+          </video>
           <h3 class="font-bold text-xl">Attributes</h3>
           <section>
             <strong>Source:</strong>

lib/pinchflat_web/router.ex

@@ -28,10 +28,11 @@ defmodule PinchflatWeb.Router do
     end
   end
 
-  # Other scopes may use custom stacks.
+  # Routes in here are NOT protected by basic auth. This is necessary for
-  # scope "/api", PinchflatWeb do
+  # media streaming to work for RSS podcast feeds.
-  #   pipe_through :api
+  scope "/", PinchflatWeb do
-  # end
+    get "/media/:id/stream", MediaItems.MediaItemController, :stream
+  end
 
   # Enable LiveDashboard and Swoosh mailbox preview in development
   if Application.compile_env(:pinchflat, :dev_routes) do

test/pinchflat_web/controllers/media_item_controller_test.exs

@@ -66,6 +66,147 @@ defmodule PinchflatWeb.MediaItemControllerTest do
     end
   end
 
+  describe "streaming media" do
+    test "returns 404 if the media isn't found", %{conn: conn} do
+      media_item = media_item_fixture()
+      conn = get(conn, ~p"/media/#{media_item.id}/stream")
+
+      assert conn.status == 404
+    end
+
+    test "automatically sets the content type", %{conn: conn} do
+      media_item = media_item_with_attachments()
+      conn = get(conn, ~p"/media/#{media_item.id}/stream")
+
+      assert {"content-type", "video/mp4; charset=utf-8"} in conn.resp_headers
+    end
+
+    test "sets the content length", %{conn: conn} do
+      media_item = media_item_with_attachments()
+      filesize = File.stat!(media_item.media_filepath).size
+
+      conn = get(conn, ~p"/media/#{media_item.id}/stream")
+
+      assert {"content-length", to_string(filesize)} in conn.resp_headers
+    end
+  end
+
+  describe "streaming media when range is valid" do
+    setup do
+      media_item = media_item_with_attachments()
+
+      %{media_item: media_item}
+    end
+
+    test "sets the correct status and headers", %{conn: conn, media_item: media_item} do
+      filesize = File.stat!(media_item.media_filepath).size
+
+      conn =
+        conn
+        |> put_req_header("range", "bytes=0-100")
+        |> get(~p"/media/#{media_item.id}/stream")
+
+      assert conn.status == 206
+      assert {"content-range", "bytes 0-100/#{filesize}"} in conn.resp_headers
+      assert {"content-length", "101"} in conn.resp_headers
+    end
+
+    test "streams the specified range", %{conn: conn, media_item: media_item} do
+      conn =
+        conn
+        |> put_req_header("range", "bytes=0-100")
+        |> get(~p"/media/#{media_item.id}/stream")
+
+      assert byte_size(conn.resp_body) == 101
+    end
+
+    test "supports range offsets", %{conn: conn, media_item: media_item} do
+      contents = File.read!(media_item.media_filepath)
+      expected = String.slice(contents, 100..200)
+
+      conn =
+        conn
+        |> put_req_header("range", "bytes=100-200")
+        |> get(~p"/media/#{media_item.id}/stream")
+
+      assert conn.resp_body == expected
+    end
+
+    test "returns as expected if the requested range is larger than the file", %{conn: conn, media_item: media_item} do
+      contents = File.read!(media_item.media_filepath)
+      filesize = File.stat!(media_item.media_filepath).size
+
+      conn =
+        conn
+        |> put_req_header("range", "bytes=0-#{filesize * 10}")
+        |> get(~p"/media/#{media_item.id}/stream")
+
+      assert conn.resp_body == contents
+      assert {"content-range", "bytes 0-#{filesize - 1}/#{filesize}"} in conn.resp_headers
+      assert {"content-length", to_string(filesize)} in conn.resp_headers
+    end
+
+    test "supports endless ranges", %{conn: conn, media_item: media_item} do
+      contents = File.read!(media_item.media_filepath)
+
+      conn =
+        conn
+        |> put_req_header("range", "bytes=0-")
+        |> get(~p"/media/#{media_item.id}/stream")
+
+      assert conn.resp_body == contents
+    end
+
+    test "supports endless ranges with offsets", %{conn: conn, media_item: media_item} do
+      contents = File.read!(media_item.media_filepath)
+      {_, expected} = String.split_at(contents, 100)
+
+      conn =
+        conn
+        |> put_req_header("range", "bytes=100-")
+        |> get(~p"/media/#{media_item.id}/stream")
+
+      assert conn.resp_body == expected
+    end
+  end
+
+  describe "streaming media when range is invalid or not present" do
+    setup do
+      media_item = media_item_with_attachments()
+
+      %{media_item: media_item}
+    end
+
+    test "sets the correct status and headers", %{conn: conn, media_item: media_item} do
+      filesize = File.stat!(media_item.media_filepath).size
+
+      conn = get(conn, ~p"/media/#{media_item.id}/stream")
+
+      assert conn.status == 200
+      assert {"content-length", to_string(filesize)} in conn.resp_headers
+    end
+
+    test "streams the entire file", %{conn: conn, media_item: media_item} do
+      contents = File.read!(media_item.media_filepath)
+
+      conn = get(conn, ~p"/media/#{media_item.id}/stream")
+
+      assert conn.resp_body == contents
+    end
+
+    test "doesn't blow up if the range header is invalid", %{conn: conn, media_item: media_item} do
+      contents = File.read!(media_item.media_filepath)
+
+      conn =
+        conn
+        |> put_req_header("range", "bytes=-")
+        |> get(~p"/media/#{media_item.id}/stream")
+
+      assert conn.status == 200
+      assert conn.resp_body == contents
+    end
+  end
+
   defp create_media_item(_) do
     media_item = media_item_fixture()
     %{media_item: media_item}

test/support/fixtures/media_fixtures.ex

@@ -49,7 +49,7 @@ defmodule Pinchflat.MediaFixtures do
       Path.join([
         Application.get_env(:pinchflat, :media_directory),
         "#{:rand.uniform(1_000_000)}",
-        "#{:rand.uniform(1_000_000)}_media.mkv"
+        "#{:rand.uniform(1_000_000)}_media.mp4"
       ])
 
     fixture_media_filepath =