staticnoCT

lib/pleroma/web/plugs/static_no_content_type.ex

@@ -0,0 +1,469 @@
+# This is almost identical to Plug.Static from Plug 1.15.3 (2024-01-16)
+# It being copied is a temporary measure to fix an urgent bug without
+# needing to wait for merge of a suitable patch upstream
+# The differences are:
+#  - this leading comment
+#  - renaming of the module from 'Plug.Static' to 'Pleroma.Web.Plugs.StaticNoCT'
+#  - additon of set_content_type option
+
+defmodule Pleroma.Web.Plugs.StaticNoCT do
+  @moduledoc """
+  A plug for serving static assets.
+
+  It requires two options:
+
+    * `:at` - the request path to reach for static assets.
+      It must be a string.
+
+    * `:from` - the file system path to read static assets from.
+      It can be either: a string containing a file system path, an
+      atom representing the application name (where assets will
+      be served from `priv/static`), a tuple containing the
+      application name and the directory to serve assets from (besides
+      `priv/static`), or an MFA tuple.
+
+  The preferred form is to use `:from` with an atom or tuple, since
+  it will make your application independent from the starting directory.
+  For example, if you pass:
+
+      plug Plug.Static, from: "priv/app/path"
+
+  Plug.Static will be unable to serve assets if you build releases
+  or if you change the current directory. Instead do:
+
+      plug Plug.Static, from: {:app_name, "priv/app/path"}
+
+  If a static asset cannot be found, `Plug.Static` simply forwards
+  the connection to the rest of the pipeline.
+
+  ## Cache mechanisms
+
+  `Plug.Static` uses etags for HTTP caching. This means browsers/clients
+  should cache assets on the first request and validate the cache on
+  following requests, not downloading the static asset once again if it
+  has not changed. The cache-control for etags is specified by the
+  `cache_control_for_etags` option and defaults to `"public"`.
+
+  However, `Plug.Static` also supports direct cache control by using
+  versioned query strings. If the request query string starts with
+  "?vsn=", `Plug.Static` assumes the application is versioning assets
+  and does not set the `ETag` header, meaning the cache behaviour will
+  be specified solely by the `cache_control_for_vsn_requests` config,
+  which defaults to `"public, max-age=31536000"`.
+
+  ## Options
+
+    * `:encodings` - list of 2-ary tuples where first value is value of
+      the `Accept-Encoding` header and second is extension of the file to
+      be served if given encoding is accepted by client. Entries will be tested
+      in order in list, so entries higher in list will be preferred. Defaults
+      to: `[]`.
+
+      In addition to setting this value directly it supports 2 additional
+      options for compatibility reasons:
+
+        + `:brotli` - will append `{"br", ".br"}` to the encodings list.
+        + `:gzip` - will append `{"gzip", ".gz"}` to the encodings list.
+
+      Additional options will be added in the above order (Brotli takes
+      preference over Gzip) to reflect older behaviour which was set due
+      to fact that Brotli in general provides better compression ratio than
+      Gzip.
+
+    * `:cache_control_for_etags` - sets the cache header for requests
+      that use etags. Defaults to `"public"`.
+
+    * `:etag_generation` - specify a `{module, function, args}` to be used
+      to generate   an etag. The `path` of the resource will be passed to
+      the function, as well as the `args`. If this option is not supplied,
+      etags will be generated based off of file size and modification time.
+      Note it is [recommended for the etag value to be quoted](https://tools.ietf.org/html/rfc7232#section-2.3),
+      which Plug won't do automatically.
+
+    * `:cache_control_for_vsn_requests` - sets the cache header for
+      requests starting with "?vsn=" in the query string. Defaults to
+      `"public, max-age=31536000"`.
+
+    * `:only` - filters which requests to serve. This is useful to avoid
+      file system access on every request when this plug is mounted
+      at `"/"`. For example, if `only: ["images", "favicon.ico"]` is
+      specified, only files in the "images" directory and the
+      "favicon.ico" file will be served by `Plug.Static`.
+      Note that `Plug.Static` matches these filters against request
+      uri and not against the filesystem. When requesting
+      a file with name containing non-ascii or special characters,
+      you should use urlencoded form. For example, you should write
+      `only: ["file%20name"]` instead of `only: ["file name"]`.
+      Defaults to `nil` (no filtering).
+
+    * `:only_matching` - a relaxed version of `:only` that will
+      serve any request as long as one of the given values matches the
+      given path. For example, `only_matching: ["images", "favicon"]`
+      will match any request that starts at "images" or "favicon",
+      be it "/images/foo.png", "/images-high/foo.png", "/favicon.ico"
+      or "/favicon-high.ico". Such matches are useful when serving
+      digested files at the root. Defaults to `nil` (no filtering).
+
+    * `:headers` - other headers to be set when serving static assets. Specify either
+      an enum of key-value pairs or a `{module, function, args}` to return an enum. The
+      `conn` will be passed to the function, as well as the `args`.
+
+    * `:content_types` - custom MIME type mapping. As a map with filename as key
+      and content type as value. For example:
+      `content_types: %{"apple-app-site-association" => "application/json"}`.
+
+    * `:set_content_type` - by default Plug.Static (re)sets the content type header
+      using auto-detection and the `:content_types` map. But when set to `false`
+      no content-type header will be inserted instead retaining the original
+      value or lack thereof. This can be useful when custom logic for appropiate
+      content types is needed which cannot be reasonably expressed as a static
+      filename map.
+
+  ## Examples
+
+  This plug can be mounted in a `Plug.Builder` pipeline as follows:
+
+      defmodule MyPlug do
+        use Plug.Builder
+
+        plug Plug.Static,
+          at: "/public",
+          from: :my_app,
+          only: ~w(images robots.txt)
+        plug :not_found
+
+        def not_found(conn, _) do
+          send_resp(conn, 404, "not found")
+        end
+      end
+
+  """
+
+  @behaviour Plug
+  @allowed_methods ~w(GET HEAD)
+
+  import Plug.Conn
+  alias Plug.Conn
+
+  # In this module, the `:prim_file` Erlang module along with the `:file_info`
+  # record are used instead of the more common and Elixir-y `File` module and
+  # `File.Stat` struct, respectively. The reason behind this is performance: all
+  # the `File` operations pass through a single process in order to support node
+  # operations that we simply don't need when serving assets.
+
+  require Record
+  Record.defrecordp(:file_info, Record.extract(:file_info, from_lib: "kernel/include/file.hrl"))
+
+  defmodule InvalidPathError do
+    defexception message: "invalid path for static asset", plug_status: 400
+  end
+
+  @impl true
+  def init(opts) do
+    from =
+      case Keyword.fetch!(opts, :from) do
+        {_, _} = from -> from
+        {_, _, _} = from -> from
+        from when is_atom(from) -> {from, "priv/static"}
+        from when is_binary(from) -> from
+        _ -> raise ArgumentError, ":from must be an atom, a binary or a tuple"
+      end
+
+    encodings =
+      opts
+      |> Keyword.get(:encodings, [])
+      |> maybe_add("br", ".br", Keyword.get(opts, :brotli, false))
+      |> maybe_add("gzip", ".gz", Keyword.get(opts, :gzip, false))
+
+    %{
+      encodings: encodings,
+      only_rules: {Keyword.get(opts, :only, []), Keyword.get(opts, :only_matching, [])},
+      qs_cache: Keyword.get(opts, :cache_control_for_vsn_requests, "public, max-age=31536000"),
+      et_cache: Keyword.get(opts, :cache_control_for_etags, "public"),
+      et_generation: Keyword.get(opts, :etag_generation, nil),
+      headers: Keyword.get(opts, :headers, %{}),
+      content_types: Keyword.get(opts, :content_types, %{}),
+      set_content_type: Keyword.get(opts, :set_content_type, true),
+      from: from,
+      at: opts |> Keyword.fetch!(:at) |> Plug.Router.Utils.split()
+    }
+  end
+
+  @impl true
+  def call(
+        conn = %Conn{method: meth},
+        %{at: at, only_rules: only_rules, from: from, encodings: encodings} = options
+      )
+      when meth in @allowed_methods do
+    segments = subset(at, conn.path_info)
+
+    if allowed?(only_rules, segments) do
+      segments = Enum.map(segments, &uri_decode/1)
+
+      if invalid_path?(segments) do
+        raise InvalidPathError, "invalid path for static asset: #{conn.request_path}"
+      end
+
+      path = path(from, segments)
+      range = get_req_header(conn, "range")
+      encoding = file_encoding(conn, path, range, encodings)
+      serve_static(encoding, conn, segments, range, options)
+    else
+      conn
+    end
+  end
+
+  def call(conn, _options) do
+    conn
+  end
+
+  defp uri_decode(path) do
+    # TODO: Remove rescue as this can't fail from Elixir v1.13
+    try do
+      URI.decode(path)
+    rescue
+      ArgumentError ->
+        raise InvalidPathError
+    end
+  end
+
+  defp allowed?(_only_rules, []), do: false
+  defp allowed?({[], []}, _list), do: true
+
+  defp allowed?({full, prefix}, [h | _]) do
+    h in full or (prefix != [] and match?({0, _}, :binary.match(h, prefix)))
+  end
+
+  defp maybe_put_content_type(conn, false, _, _), do: conn
+
+  defp maybe_put_content_type(conn, _, types, filename) do
+    content_type = Map.get(types, filename) || MIME.from_path(filename)
+
+    conn
+    |> put_resp_header("content-type", content_type)
+  end
+
+  defp serve_static({content_encoding, file_info, path}, conn, segments, range, options) do
+    %{
+      qs_cache: qs_cache,
+      et_cache: et_cache,
+      et_generation: et_generation,
+      headers: headers,
+      content_types: types,
+      set_content_type: set_content_type
+    } = options
+
+    case put_cache_header(conn, qs_cache, et_cache, et_generation, file_info, path) do
+      {:stale, conn} ->
+        filename = List.last(segments)
+
+        conn
+        |> maybe_put_content_type(set_content_type, types, filename)
+        |> put_resp_header("accept-ranges", "bytes")
+        |> maybe_add_encoding(content_encoding)
+        |> merge_headers(headers)
+        |> serve_range(file_info, path, range, options)
+
+      {:fresh, conn} ->
+        conn
+        |> maybe_add_vary(options)
+        |> send_resp(304, "")
+        |> halt()
+    end
+  end
+
+  defp serve_static(:error, conn, _segments, _range, _options) do
+    conn
+  end
+
+  defp serve_range(conn, file_info, path, [range], options) do
+    file_info(size: file_size) = file_info
+
+    with %{"bytes" => bytes} <- Plug.Conn.Utils.params(range),
+         {range_start, range_end} <- start_and_end(bytes, file_size) do
+      send_range(conn, path, range_start, range_end, file_size, options)
+    else
+      _ -> send_entire_file(conn, path, options)
+    end
+  end
+
+  defp serve_range(conn, _file_info, path, _range, options) do
+    send_entire_file(conn, path, options)
+  end
+
+  defp start_and_end("-" <> rest, file_size) do
+    case Integer.parse(rest) do
+      {last, ""} when last > 0 and last <= file_size -> {file_size - last, file_size - 1}
+      _ -> :error
+    end
+  end
+
+  defp start_and_end(range, file_size) do
+    case Integer.parse(range) do
+      {first, "-"} when first >= 0 ->
+        {first, file_size - 1}
+
+      {first, "-" <> rest} when first >= 0 ->
+        case Integer.parse(rest) do
+          {last, ""} when last >= first -> {first, min(last, file_size - 1)}
+          _ -> :error
+        end
+
+      _ ->
+        :error
+    end
+  end
+
+  defp send_range(conn, path, 0, range_end, file_size, options) when range_end == file_size - 1 do
+    send_entire_file(conn, path, options)
+  end
+
+  defp send_range(conn, path, range_start, range_end, file_size, _options) do
+    length = range_end - range_start + 1
+
+    conn
+    |> put_resp_header("content-range", "bytes #{range_start}-#{range_end}/#{file_size}")
+    |> send_file(206, path, range_start, length)
+    |> halt()
+  end
+
+  defp send_entire_file(conn, path, options) do
+    conn
+    |> maybe_add_vary(options)
+    |> send_file(200, path)
+    |> halt()
+  end
+
+  defp maybe_add_encoding(conn, nil), do: conn
+  defp maybe_add_encoding(conn, ce), do: put_resp_header(conn, "content-encoding", ce)
+
+  defp maybe_add_vary(conn, %{encodings: encodings}) do
+    # If we serve gzip or brotli at any moment, we need to set the proper vary
+    # header regardless of whether we are serving gzip content right now.
+    # See: http://www.fastly.com/blog/best-practices-for-using-the-vary-header/
+    if encodings != [] do
+      update_in(conn.resp_headers, &[{"vary", "Accept-Encoding"} | &1])
+    else
+      conn
+    end
+  end
+
+  defp put_cache_header(
+         %Conn{query_string: "vsn=" <> _} = conn,
+         qs_cache,
+         _et_cache,
+         _et_generation,
+         _file_info,
+         _path
+       )
+       when is_binary(qs_cache) do
+    {:stale, put_resp_header(conn, "cache-control", qs_cache)}
+  end
+
+  defp put_cache_header(conn, _qs_cache, et_cache, et_generation, file_info, path)
+       when is_binary(et_cache) do
+    etag = etag_for_path(file_info, et_generation, path)
+
+    conn =
+      conn
+      |> put_resp_header("cache-control", et_cache)
+      |> put_resp_header("etag", etag)
+
+    if etag in get_req_header(conn, "if-none-match") do
+      {:fresh, conn}
+    else
+      {:stale, conn}
+    end
+  end
+
+  defp put_cache_header(conn, _, _, _, _, _) do
+    {:stale, conn}
+  end
+
+  defp etag_for_path(file_info, et_generation, path) do
+    case et_generation do
+      {module, function, args} ->
+        apply(module, function, [path | args])
+
+      nil ->
+        file_info(size: size, mtime: mtime) = file_info
+        <<?", {size, mtime} |> :erlang.phash2() |> Integer.to_string(16)::binary, ?">>
+    end
+  end
+
+  defp file_encoding(conn, path, [_range], _encodings) do
+    # We do not support compression for range queries.
+    file_encoding(conn, path, nil, [])
+  end
+
+  defp file_encoding(conn, path, _range, encodings) do
+    encoded =
+      Enum.find_value(encodings, fn {encoding, ext} ->
+        if file_info = accept_encoding?(conn, encoding) && regular_file_info(path <> ext) do
+          {encoding, file_info, path <> ext}
+        end
+      end)
+
+    cond do
+      not is_nil(encoded) ->
+        encoded
+
+      file_info = regular_file_info(path) ->
+        {nil, file_info, path}
+
+      true ->
+        :error
+    end
+  end
+
+  defp regular_file_info(path) do
+    case :prim_file.read_file_info(path) do
+      {:ok, file_info(type: :regular) = file_info} ->
+        file_info
+
+      _ ->
+        nil
+    end
+  end
+
+  defp accept_encoding?(conn, encoding) do
+    encoding? = &String.contains?(&1, [encoding, "*"])
+
+    Enum.any?(get_req_header(conn, "accept-encoding"), fn accept ->
+      accept |> Plug.Conn.Utils.list() |> Enum.any?(encoding?)
+    end)
+  end
+
+  defp maybe_add(list, key, value, true), do: list ++ [{key, value}]
+  defp maybe_add(list, _key, _value, false), do: list
+
+  defp path({module, function, arguments}, segments)
+       when is_atom(module) and is_atom(function) and is_list(arguments),
+       do: Enum.join([apply(module, function, arguments) | segments], "/")
+
+  defp path({app, from}, segments) when is_atom(app) and is_binary(from),
+    do: Enum.join([Application.app_dir(app), from | segments], "/")
+
+  defp path(from, segments),
+    do: Enum.join([from | segments], "/")
+
+  defp subset([h | expected], [h | actual]), do: subset(expected, actual)
+  defp subset([], actual), do: actual
+  defp subset(_, _), do: []
+
+  defp invalid_path?(list) do
+    invalid_path?(list, :binary.compile_pattern(["/", "\\", ":", "\0"]))
+  end
+
+  defp invalid_path?([h | _], _match) when h in [".", "..", ""], do: true
+  defp invalid_path?([h | t], match), do: String.contains?(h, match) or invalid_path?(t)
+  defp invalid_path?([], _match), do: false
+
+  defp merge_headers(conn, {module, function, args}) do
+    merge_headers(conn, apply(module, function, [conn | args]))
+  end
+
+  defp merge_headers(conn, headers) do
+    merge_resp_headers(conn, headers)
+  end
+end