1 # Pleroma: A lightweight social networking server
2 # Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
3 # SPDX-License-Identifier: AGPL-3.0-only
5 defmodule Pleroma.ReverseProxy do
8 @keep_req_headers ~w(accept user-agent accept-encoding cache-control if-modified-since) ++
9 ~w(if-unmodified-since if-none-match if-range range)
10 @resp_cache_headers ~w(etag date last-modified)
11 @keep_resp_headers @resp_cache_headers ++
12 ~w(content-type content-disposition content-encoding content-range) ++
13 ~w(accept-ranges vary)
14 @default_cache_control_header "public, max-age=1209600"
15 @valid_resp_codes [200, 206, 304]
16 @max_read_duration :timer.seconds(30)
17 @max_body_length :infinity
18 @failed_request_ttl :timer.seconds(60)
24 Pleroma.ReverseProxy.call(conn, url, options)
26 It is not meant to be added into a plug pipeline, but to be called from another plug or controller.
28 Supports `#{inspect(@methods)}` HTTP methods, and only allows `#{inspect(@valid_resp_codes)}` status codes.
30 Responses are chunked to the client while downloading from the upstream.
32 Some request / responses headers are preserved:
34 * request: `#{inspect(@keep_req_headers)}`
35 * response: `#{inspect(@keep_resp_headers)}`
39 * `redirect_on_failure` (default `false`). Redirects the client to the real remote URL if there's any HTTP
40 errors. Any error during body processing will not be redirected as the response is chunked. This may expose
41 remote URL, clients IPs, ….
43 * `max_body_length` (default `#{inspect(@max_body_length)}`): limits the content length to be approximately the
44 specified length. It is validated with the `content-length` header and also verified when proxying.
46 * `max_read_duration` (default `#{inspect(@max_read_duration)}` ms): the total time the connection is allowed to
47 read from the remote upstream.
49 * `failed_request_ttl` (default `#{inspect(@failed_request_ttl)}` ms): the time the failed request is cached and cannot be retried.
51 * `inline_content_types`:
52 * `true` will not alter `content-disposition` (up to the upstream),
53 * `false` will add `content-disposition: attachment` to any request,
54 * a list of whitelisted content types
56 * `keep_user_agent` will forward the client's user-agent to the upstream. This may be useful if the upstream is
57 doing content transformation (encoding, …) depending on the request.
59 * `req_headers`, `resp_headers` additional headers.
61 * `http`: options for [hackney](https://github.com/benoitc/hackney).
64 @default_hackney_options [pool: :media]
66 @inline_content_types [
83 {:keep_user_agent, boolean}
84 | {:max_read_duration, :timer.time() | :infinity}
85 | {:max_body_length, non_neg_integer() | :infinity}
86 | {:failed_request_ttl, :timer.time() | :infinity}
88 | {:req_headers, [{String.t(), String.t()}]}
89 | {:resp_headers, [{String.t(), String.t()}]}
90 | {:inline_content_types, boolean() | [String.t()]}
91 | {:redirect_on_failure, boolean()}
93 @spec call(Plug.Conn.t(), url :: String.t(), [option()]) :: Plug.Conn.t()
94 def call(_conn, _url, _opts \\ [])
96 def call(conn = %{method: method}, url, opts) when method in @methods do
98 Pleroma.HTTP.Connection.hackney_options([])
99 |> Keyword.merge(@default_hackney_options)
100 |> Keyword.merge(Keyword.get(opts, :http, []))
101 |> HTTP.process_request_options()
103 req_headers = build_req_headers(conn.req_headers, opts)
106 if filename = Pleroma.Web.MediaProxy.filename(url) do
107 Keyword.put_new(opts, :attachment_name, filename)
112 with {:ok, nil} <- Cachex.get(:failed_proxy_url_cache, url),
113 {:ok, code, headers, client} <- request(method, url, req_headers, hackney_opts),
115 header_length_constraint(
117 Keyword.get(opts, :max_body_length, @max_body_length)
119 response(conn, client, url, code, headers, opts)
123 |> error_or_redirect(url, 500, "Request failed", opts)
126 {:ok, code, headers} ->
127 head_response(conn, url, code, headers, opts)
130 {:error, {:invalid_http_response, code}} ->
131 Logger.error("#{__MODULE__}: request to #{inspect(url)} failed with HTTP status #{code}")
132 track_failed_url(url, code, opts)
135 |> error_or_redirect(
138 "Request failed: " <> Plug.Conn.Status.reason_phrase(code),
144 Logger.error("#{__MODULE__}: request to #{inspect(url)} failed: #{inspect(error)}")
145 track_failed_url(url, error, opts)
148 |> error_or_redirect(url, 500, "Request failed", opts)
153 def call(conn, _, _) do
155 |> send_resp(400, Plug.Conn.Status.reason_phrase(400))
159 defp request(method, url, headers, hackney_opts) do
160 Logger.debug("#{__MODULE__} #{method} #{url} #{inspect(headers)}")
161 method = method |> String.downcase() |> String.to_existing_atom()
163 case client().request(method, url, headers, "", hackney_opts) do
164 {:ok, code, headers, client} when code in @valid_resp_codes ->
165 {:ok, code, downcase_headers(headers), client}
167 {:ok, code, headers} when code in @valid_resp_codes ->
168 {:ok, code, downcase_headers(headers)}
171 {:error, {:invalid_http_response, code}}
178 defp response(conn, client, url, status, headers, opts) do
181 |> put_resp_headers(build_resp_headers(headers, opts))
182 |> send_chunked(status)
183 |> chunk_reply(client, opts)
189 {:error, :closed, conn} ->
190 client().close(client)
193 {:error, error, conn} ->
195 "#{__MODULE__} request to #{url} failed while reading/chunking: #{inspect(error)}"
198 client().close(client)
203 defp chunk_reply(conn, client, opts) do
204 chunk_reply(conn, client, opts, 0, 0)
207 defp chunk_reply(conn, client, opts, sent_so_far, duration) do
208 with {:ok, duration} <-
211 Keyword.get(opts, :max_read_duration, @max_read_duration)
213 {:ok, data} <- client().stream_body(client),
214 {:ok, duration} <- increase_read_duration(duration),
215 sent_so_far = sent_so_far + byte_size(data),
217 body_size_constraint(
219 Keyword.get(opts, :max_body_length, @max_body_length)
221 {:ok, conn} <- chunk(conn, data) do
222 chunk_reply(conn, client, opts, sent_so_far, duration)
225 {:error, error} -> {:error, error, conn}
229 defp head_response(conn, _url, code, headers, opts) do
231 |> put_resp_headers(build_resp_headers(headers, opts))
232 |> send_resp(code, "")
235 defp error_or_redirect(conn, url, code, body, opts) do
236 if Keyword.get(opts, :redirect_on_failure, false) do
238 |> Phoenix.Controller.redirect(external: url)
242 |> send_resp(code, body)
247 defp downcase_headers(headers) do
248 Enum.map(headers, fn {k, v} ->
249 {String.downcase(k), v}
253 defp get_content_type(headers) do
255 List.keyfind(headers, "content-type", 0, {"content-type", "application/octet-stream"})
257 [content_type | _] = String.split(content_type, ";")
261 defp put_resp_headers(conn, headers) do
262 Enum.reduce(headers, conn, fn {k, v}, conn ->
263 put_resp_header(conn, k, v)
267 defp build_req_headers(headers, opts) do
269 |> downcase_headers()
270 |> Enum.filter(fn {k, _} -> k in @keep_req_headers end)
272 headers = headers ++ Keyword.get(opts, :req_headers, [])
274 if Keyword.get(opts, :keep_user_agent, false) do
279 {"user-agent", Pleroma.Application.user_agent()}
287 defp build_resp_headers(headers, opts) do
289 |> Enum.filter(fn {k, _} -> k in @keep_resp_headers end)
290 |> build_resp_cache_headers(opts)
291 |> build_resp_content_disposition_header(opts)
292 |> (fn headers -> headers ++ Keyword.get(opts, :resp_headers, []) end).()
295 defp build_resp_cache_headers(headers, _opts) do
296 has_cache? = Enum.any?(headers, fn {k, _} -> k in @resp_cache_headers end)
300 # There's caching header present but no cache-control -- we need to set our own
301 # as Plug defaults to "max-age=0, private, must-revalidate"
306 {"cache-control", @default_cache_control_header}
314 {"cache-control", @default_cache_control_header}
319 defp build_resp_content_disposition_header(headers, opts) do
320 opt = Keyword.get(opts, :inline_content_types, @inline_content_types)
322 content_type = get_content_type(headers)
326 is_list(opt) && !Enum.member?(opt, content_type) -> true
334 {{"content-disposition", content_disposition_string}, _} =
335 List.keytake(headers, "content-disposition", 0)
339 ~r/filename="((?:[^"\\]|\\.)*)"/u,
340 content_disposition_string || "",
341 capture: :all_but_first
346 MatchError -> Keyword.get(opts, :attachment_name, "attachment")
349 disposition = "attachment; filename=\"#{name}\""
351 List.keystore(headers, "content-disposition", 0, {"content-disposition", disposition})
357 defp header_length_constraint(headers, limit) when is_integer(limit) and limit > 0 do
358 with {_, size} <- List.keyfind(headers, "content-length", 0),
359 {size, _} <- Integer.parse(size),
360 true <- size <= limit do
364 {:error, :body_too_large}
371 defp header_length_constraint(_, _), do: :ok
373 defp body_size_constraint(size, limit) when is_integer(limit) and limit > 0 and size >= limit do
374 {:error, :body_too_large}
377 defp body_size_constraint(_, _), do: :ok
379 defp check_read_duration(duration, max)
380 when is_integer(duration) and is_integer(max) and max > 0 do
382 {:error, :read_duration_exceeded}
384 {:ok, {duration, :erlang.system_time(:millisecond)}}
388 defp check_read_duration(_, _), do: {:ok, :no_duration_limit, :no_duration_limit}
390 defp increase_read_duration({previous_duration, started})
391 when is_integer(previous_duration) and is_integer(started) do
392 duration = :erlang.system_time(:millisecond) - started
393 {:ok, previous_duration + duration}
396 defp increase_read_duration(_) do
397 {:ok, :no_duration_limit, :no_duration_limit}
400 defp client, do: Pleroma.ReverseProxy.Client
402 defp track_failed_url(url, error, opts) do
404 unless error in [:body_too_large, 400, 204] do
405 Keyword.get(opts, :failed_request_ttl, @failed_request_ttl)
410 Cachex.put(:failed_proxy_url_cache, url, true, ttl: ttl)