Add JPEG-XL, AVIF, and WebP support to the reverse proxy. All three are supported in WebKit browsers; the latter two are supported in Gecko and Blink.
		
			
				
	
	
		
			353 lines
		
	
	
	
		
			11 KiB
		
	
	
	
		
			Elixir
		
	
	
	
	
	
			
		
		
	
	
			353 lines
		
	
	
	
		
			11 KiB
		
	
	
	
		
			Elixir
		
	
	
	
	
	
# Pleroma: A lightweight social networking server
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# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
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# SPDX-License-Identifier: AGPL-3.0-only
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defmodule Pleroma.ReverseProxy do
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  @range_headers ~w(range if-range)
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  @keep_req_headers ~w(accept accept-encoding cache-control if-modified-since) ++
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                      ~w(if-unmodified-since if-none-match) ++ @range_headers
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  @resp_cache_headers ~w(etag date last-modified)
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  @keep_resp_headers @resp_cache_headers ++
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                       ~w(content-length content-type content-disposition content-encoding) ++
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                       ~w(content-range accept-ranges vary expires)
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  @default_cache_control_header "public, max-age=1209600"
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  @valid_resp_codes [200, 206, 304]
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  @max_read_duration :timer.seconds(30)
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  @max_body_length :infinity
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  @failed_request_ttl :timer.seconds(60)
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  @methods ~w(GET HEAD)
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  @cachex Pleroma.Config.get([:cachex, :provider], Cachex)
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  def max_read_duration_default, do: @max_read_duration
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  def default_cache_control_header, do: @default_cache_control_header
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  @moduledoc """
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  A reverse proxy.
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      Pleroma.ReverseProxy.call(conn, url, options)
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  It is not meant to be added into a plug pipeline, but to be called from another plug or controller.
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  Supports `#{inspect(@methods)}` HTTP methods, and only allows `#{inspect(@valid_resp_codes)}` status codes.
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  Responses are chunked to the client while downloading from the upstream.
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  Some request / responses headers are preserved:
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  * request: `#{inspect(@keep_req_headers)}`
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  * response: `#{inspect(@keep_resp_headers)}`
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  Options:
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  * `redirect_on_failure` (default `false`). Redirects the client to the real remote URL if there's any HTTP
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  errors. Any error during body processing will not be redirected as the response is chunked. This may expose
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  remote URL, clients IPs, ….
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  * `max_body_length` (default `#{inspect(@max_body_length)}`): limits the content length to be approximately the
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  specified length. It is validated with the `content-length` header and also verified when proxying.
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  * `max_read_duration` (default `#{inspect(@max_read_duration)}` ms): the total time the connection is allowed to
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  read from the remote upstream.
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  * `failed_request_ttl` (default `#{inspect(@failed_request_ttl)}` ms): the time the failed request is cached and cannot be retried.
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  * `inline_content_types`:
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    * `true` will not alter `content-disposition` (up to the upstream),
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    * `false` will add `content-disposition: attachment` to any request,
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    * a list of whitelisted content types
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  * `req_headers`, `resp_headers` additional headers.
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  """
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  @inline_content_types [
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    "image/avif",
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    "image/gif",
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    "image/jpeg",
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    "image/jpg",
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    "image/jxl",
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    "image/png",
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    "image/svg+xml",
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    "image/webp",
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    "audio/mpeg",
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    "audio/mp3",
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    "video/webm",
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    "video/mp4",
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    "video/quicktime"
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  ]
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  require Logger
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  import Plug.Conn
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  @type option() ::
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          {:max_read_duration, :timer.time() | :infinity}
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          | {:max_body_length, non_neg_integer() | :infinity}
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          | {:failed_request_ttl, :timer.time() | :infinity}
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          | {:http, []}
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          | {:req_headers, [{String.t(), String.t()}]}
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          | {:resp_headers, [{String.t(), String.t()}]}
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          | {:inline_content_types, boolean() | [String.t()]}
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          | {:redirect_on_failure, boolean()}
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  @spec call(Plug.Conn.t(), url :: String.t(), [option()]) :: Plug.Conn.t()
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  def call(_conn, _url, _opts \\ [])
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  def call(conn = %{method: method}, url, opts) when method in @methods do
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    client_opts = Keyword.get(opts, :http, [])
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    req_headers = build_req_headers(conn.req_headers, opts)
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    opts =
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      if filename = Pleroma.Web.MediaProxy.filename(url) do
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        Keyword.put_new(opts, :attachment_name, filename)
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      else
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        opts
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      end
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    with {:ok, nil} <- @cachex.get(:failed_proxy_url_cache, url),
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         {:ok, status, headers, body} <- request(method, url, req_headers, client_opts),
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         :ok <-
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           header_length_constraint(
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             headers,
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             Keyword.get(opts, :max_body_length, @max_body_length)
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           ) do
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      conn
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      |> put_private(:proxied_url, url)
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      |> response(body, status, headers, opts)
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    else
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      {:ok, true} ->
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        conn
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        |> put_private(:proxied_url, url)
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        |> error_or_redirect(500, "Request failed", opts)
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        |> halt()
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      {:ok, status, headers} ->
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        conn
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        |> put_private(:proxied_url, url)
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        |> head_response(status, headers, opts)
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        |> halt()
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      {:error, {:invalid_http_response, status}} ->
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        Logger.error(
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          "#{__MODULE__}: request to #{inspect(url)} failed with HTTP status #{status}"
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        )
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        track_failed_url(url, status, opts)
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        conn
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        |> put_private(:proxied_url, url)
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        |> error_or_redirect(
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          status,
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          "Request failed: " <> Plug.Conn.Status.reason_phrase(status),
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          opts
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        )
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        |> halt()
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      {:error, error} ->
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        Logger.error("#{__MODULE__}: request to #{inspect(url)} failed: #{inspect(error)}")
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        track_failed_url(url, error, opts)
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        conn
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        |> put_private(:proxied_url, url)
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        |> error_or_redirect(500, "Request failed", opts)
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        |> halt()
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    end
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  end
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  def call(conn, _, _) do
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    conn
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    |> send_resp(400, Plug.Conn.Status.reason_phrase(400))
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    |> halt()
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  end
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  defp request(method, url, headers, opts) do
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    Logger.debug("#{__MODULE__} #{method} #{url} #{inspect(headers)}")
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    method = method |> String.downcase() |> String.to_existing_atom()
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    opts = opts ++ [receive_timeout: @max_read_duration]
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    case Pleroma.HTTP.request(method, url, "", headers, opts) do
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      {:ok, %Tesla.Env{status: status, headers: headers, body: body}}
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      when status in @valid_resp_codes ->
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        {:ok, status, downcase_headers(headers), body}
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      {:ok, %Tesla.Env{status: status, headers: headers}} when status in @valid_resp_codes ->
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        {:ok, status, downcase_headers(headers)}
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      {:ok, %Tesla.Env{status: status}} ->
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        {:error, {:invalid_http_response, status}}
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      {:error, error} ->
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        {:error, error}
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    end
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  end
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  defp response(conn, body, status, headers, opts) do
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    Logger.debug("#{__MODULE__} #{status} #{conn.private[:proxied_url]} #{inspect(headers)}")
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    conn
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    |> put_resp_headers(build_resp_headers(headers, opts))
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    |> send_resp(status, body)
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  end
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  defp head_response(conn, status, headers, opts) do
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    Logger.debug("#{__MODULE__} #{status} #{conn.private[:proxied_url]} #{inspect(headers)}")
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    conn
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    |> put_resp_headers(build_resp_headers(headers, opts))
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    |> send_resp(status, "")
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  end
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  defp error_or_redirect(conn, status, body, opts) do
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    if Keyword.get(opts, :redirect_on_failure, false) do
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      conn
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      |> Phoenix.Controller.redirect(external: conn.private[:proxied_url])
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      |> halt()
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    else
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      conn
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      |> send_resp(status, body)
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      |> halt
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    end
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  end
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  defp downcase_headers(headers) do
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    Enum.map(headers, fn {k, v} ->
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      {String.downcase(k), v}
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    end)
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  end
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  defp get_content_type(headers) do
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    {_, content_type} =
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      List.keyfind(headers, "content-type", 0, {"content-type", "application/octet-stream"})
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    [content_type | _] = String.split(content_type, ";")
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    content_type
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  end
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  defp put_resp_headers(conn, headers) do
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    Enum.reduce(headers, conn, fn {k, v}, conn ->
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      put_resp_header(conn, k, v)
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    end)
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  end
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  defp build_req_headers(headers, opts) do
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    headers
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    |> downcase_headers()
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    |> Enum.filter(fn {k, _} -> k in @keep_req_headers end)
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    |> build_req_range_or_encoding_header(opts)
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    |> Keyword.merge(Keyword.get(opts, :req_headers, []))
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  end
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  # Disable content-encoding if any @range_headers are requested (see #1823).
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  defp build_req_range_or_encoding_header(headers, _opts) do
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    range? = Enum.any?(headers, fn {header, _} -> Enum.member?(@range_headers, header) end)
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    if range? && List.keymember?(headers, "accept-encoding", 0) do
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      List.keydelete(headers, "accept-encoding", 0)
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    else
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      headers
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    end
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  end
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  defp build_resp_headers(headers, opts) do
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    headers
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    |> Enum.filter(fn {k, _} -> k in @keep_resp_headers end)
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    |> build_resp_cache_headers(opts)
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    |> build_resp_content_disposition_header(opts)
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    |> build_csp_headers()
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    |> Keyword.merge(Keyword.get(opts, :resp_headers, []))
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  end
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  defp build_resp_cache_headers(headers, _opts) do
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    has_cache? = Enum.any?(headers, fn {k, _} -> k in @resp_cache_headers end)
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    cond do
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      has_cache? ->
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        # There's caching header present but no cache-control -- we need to set our own
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        # as Plug defaults to "max-age=0, private, must-revalidate"
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        List.keystore(
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          headers,
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          "cache-control",
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          0,
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          {"cache-control", @default_cache_control_header}
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        )
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      true ->
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        List.keystore(
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          headers,
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          "cache-control",
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          0,
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          {"cache-control", @default_cache_control_header}
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        )
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    end
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  end
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  defp build_resp_content_disposition_header(headers, opts) do
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    opt = Keyword.get(opts, :inline_content_types, @inline_content_types)
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    content_type = get_content_type(headers)
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    attachment? =
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      cond do
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        is_list(opt) && !Enum.member?(opt, content_type) -> true
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        opt == false -> true
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        true -> false
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      end
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    if attachment? do
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      name =
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        try do
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          {{"content-disposition", content_disposition_string}, _} =
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            List.keytake(headers, "content-disposition", 0)
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          [name | _] =
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            Regex.run(
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              ~r/filename="((?:[^"\\]|\\.)*)"/u,
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              content_disposition_string || "",
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              capture: :all_but_first
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            )
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          name
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        rescue
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          MatchError -> Keyword.get(opts, :attachment_name, "attachment")
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        end
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      disposition = "attachment; filename=\"#{name}\""
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      List.keystore(headers, "content-disposition", 0, {"content-disposition", disposition})
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    else
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      headers
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    end
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  end
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  defp build_csp_headers(headers) do
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    List.keystore(headers, "content-security-policy", 0, {"content-security-policy", "sandbox"})
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  end
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  defp header_length_constraint(headers, limit) when is_integer(limit) and limit > 0 do
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    with {_, size} <- List.keyfind(headers, "content-length", 0),
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         {size, _} <- Integer.parse(size),
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         true <- size <= limit do
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      :ok
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    else
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      false ->
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        {:error, :body_too_large}
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      _ ->
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        :ok
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    end
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  end
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  defp header_length_constraint(_, _), do: :ok
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  defp track_failed_url(url, error, opts) do
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    ttl =
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      unless error in [:body_too_large, 400, 204] do
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        Keyword.get(opts, :failed_request_ttl, @failed_request_ttl)
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      else
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        nil
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      end
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    @cachex.put(:failed_proxy_url_cache, url, true, ttl: ttl)
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  end
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end
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