reverse_proxy.ex 10.5 KB
Newer Older
href's avatar
href committed
1
defmodule Pleroma.ReverseProxy do
href's avatar
href committed
2
  @keep_req_headers ~w(accept user-agent accept-encoding cache-control if-modified-since if-unmodified-since if-none-match if-range range)
href's avatar
href committed
3
4
  @resp_cache_headers ~w(etag date last-modified cache-control)
  @keep_resp_headers @resp_cache_headers ++
href's avatar
href committed
5
                       ~w(content-type content-disposition content-encoding content-range accept-ranges vary)
href's avatar
href committed
6
7
  @default_cache_control_header "public, max-age=1209600"
  @valid_resp_codes [200, 206, 304]
8
  @max_read_duration :timer.seconds(30)
href's avatar
href committed
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
  @max_body_length :infinity
  @methods ~w(GET HEAD)

  @moduledoc """
  A reverse proxy.

      Pleroma.ReverseProxy.call(conn, url, options)

  It is not meant to be added into a plug pipeline, but to be called from another plug or controller.

  Supports `#{inspect(@methods)}` HTTP methods, and only allows `#{inspect(@valid_resp_codes)}` status codes.

  Responses are chunked to the client while downloading from the upstream.

  Some request / responses headers are preserved:

  * request: `#{inspect(@keep_req_headers)}`
  * response: `#{inspect(@keep_resp_headers)}`

  If no caching headers (`#{inspect(@resp_cache_headers)}`) are returned by upstream, `cache-control` will be
  set to `#{inspect(@default_cache_control_header)}`.

  Options:

  * `redirect_on_failure` (default `false`). Redirects the client to the real remote URL if there's any HTTP
  errors. Any error during body processing will not be redirected as the response is chunked. This may expose
  remote URL, clients IPs, ….

  * `max_body_length` (default `#{inspect(@max_body_length)}`): limits the content length to be approximately the
  specified length. It is validated with the `content-length` header and also verified when proxying.

  * `max_read_duration` (default `#{inspect(@max_read_duration)}` ms): the total time the connection is allowed to
  read from the remote upstream.

  * `inline_content_types`:
    * `true` will not alter `content-disposition` (up to the upstream),
    * `false` will add `content-disposition: attachment` to any request,
    * a list of whitelisted content types

    * `keep_user_agent` will forward the client's user-agent to the upstream. This may be useful if the upstream is
    doing content transformation (encoding, …) depending on the request.

  * `req_headers`, `resp_headers` additional headers.

  * `http`: options for [hackney](https://github.com/benoitc/hackney).

  """
  @hackney Application.get_env(:pleroma, :hackney, :hackney)
  @httpoison Application.get_env(:pleroma, :httpoison, HTTPoison)

Hakaba Hitoyo's avatar
Hakaba Hitoyo committed
59
  @default_hackney_options []
href's avatar
href committed
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87

  @inline_content_types [
    "image/gif",
    "image/jpeg",
    "image/jpg",
    "image/png",
    "image/svg+xml",
    "audio/mpeg",
    "audio/mp3",
    "video/webm",
    "video/mp4",
    "video/quicktime"
  ]

  require Logger
  import Plug.Conn

  @type option() ::
          {:keep_user_agent, boolean}
          | {:max_read_duration, :timer.time() | :infinity}
          | {:max_body_length, non_neg_integer() | :infinity}
          | {:http, []}
          | {:req_headers, [{String.t(), String.t()}]}
          | {:resp_headers, [{String.t(), String.t()}]}
          | {:inline_content_types, boolean() | [String.t()]}
          | {:redirect_on_failure, boolean()}

  @spec call(Plug.Conn.t(), url :: String.t(), [option()]) :: Plug.Conn.t()
Maksim's avatar
Maksim committed
88
89
90
  def call(_conn, _url, _opts \\ [])

  def call(conn = %{method: method}, url, opts) when method in @methods do
href's avatar
href committed
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
    hackney_opts =
      @default_hackney_options
      |> Keyword.merge(Keyword.get(opts, :http, []))
      |> @httpoison.process_request_options()

    req_headers = build_req_headers(conn.req_headers, opts)

    opts =
      if filename = Pleroma.Web.MediaProxy.filename(url) do
        Keyword.put_new(opts, :attachment_name, filename)
      else
        opts
      end

    with {:ok, code, headers, client} <- request(method, url, req_headers, hackney_opts),
href's avatar
href committed
106
         :ok <- header_length_constraint(headers, Keyword.get(opts, :max_body_length)) do
href's avatar
href committed
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
      response(conn, client, url, code, headers, opts)
    else
      {:ok, code, headers} ->
        head_response(conn, url, code, headers, opts)
        |> halt()

      {:error, {:invalid_http_response, code}} ->
        Logger.error("#{__MODULE__}: request to #{inspect(url)} failed with HTTP status #{code}")

        conn
        |> error_or_redirect(
          url,
          code,
          "Request failed: " <> Plug.Conn.Status.reason_phrase(code),
          opts
        )
        |> halt()

      {:error, error} ->
        Logger.error("#{__MODULE__}: request to #{inspect(url)} failed: #{inspect(error)}")

        conn
        |> error_or_redirect(url, 500, "Request failed", opts)
        |> halt()
    end
  end

  def call(conn, _, _) do
    conn
    |> send_resp(400, Plug.Conn.Status.reason_phrase(400))
    |> halt()
  end

  defp request(method, url, headers, hackney_opts) do
    Logger.debug("#{__MODULE__} #{method} #{url} #{inspect(headers)}")
    method = method |> String.downcase() |> String.to_existing_atom()

    case @hackney.request(method, url, headers, "", hackney_opts) do
      {:ok, code, headers, client} when code in @valid_resp_codes ->
        {:ok, code, downcase_headers(headers), client}

      {:ok, code, headers} when code in @valid_resp_codes ->
        {:ok, code, downcase_headers(headers)}

      {:ok, code, _, _} ->
        {:error, {:invalid_http_response, code}}

      {:error, error} ->
        {:error, error}
    end
  end

  defp response(conn, client, url, status, headers, opts) do
    result =
      conn
      |> put_resp_headers(build_resp_headers(headers, opts))
      |> send_chunked(status)
      |> chunk_reply(client, opts)

    case result do
      {:ok, conn} ->
        halt(conn)

      {:error, :closed, conn} ->
        :hackney.close(client)
        halt(conn)

      {:error, error, conn} ->
        Logger.warn(
          "#{__MODULE__} request to #{url} failed while reading/chunking: #{inspect(error)}"
        )

        :hackney.close(client)
        halt(conn)
    end
  end

  defp chunk_reply(conn, client, opts) do
    chunk_reply(conn, client, opts, 0, 0)
  end

  defp chunk_reply(conn, client, opts, sent_so_far, duration) do
    with {:ok, duration} <-
           check_read_duration(
             duration,
             Keyword.get(opts, :max_read_duration, @max_read_duration)
           ),
         {:ok, data} <- @hackney.stream_body(client),
         {:ok, duration} <- increase_read_duration(duration),
         sent_so_far = sent_so_far + byte_size(data),
         :ok <- body_size_constraint(sent_so_far, Keyword.get(opts, :max_body_size)),
         {:ok, conn} <- chunk(conn, data) do
      chunk_reply(conn, client, opts, sent_so_far, duration)
    else
      :done -> {:ok, conn}
      {:error, error} -> {:error, error, conn}
    end
  end

  defp head_response(conn, _url, code, headers, opts) do
    conn
    |> put_resp_headers(build_resp_headers(headers, opts))
    |> send_resp(code, "")
  end

  defp error_or_redirect(conn, url, code, body, opts) do
    if Keyword.get(opts, :redirect_on_failure, false) do
      conn
      |> Phoenix.Controller.redirect(external: url)
      |> halt()
    else
      conn
      |> send_resp(code, body)
      |> halt
    end
  end

  defp downcase_headers(headers) do
    Enum.map(headers, fn {k, v} ->
      {String.downcase(k), v}
    end)
  end

230
  defp get_content_type(headers) do
href's avatar
href committed
231
232
233
234
    {_, content_type} =
      List.keyfind(headers, "content-type", 0, {"content-type", "application/octet-stream"})

    [content_type | _] = String.split(content_type, ";")
235
236
237
    content_type
  end

href's avatar
href committed
238
239
240
241
242
243
244
  defp put_resp_headers(conn, headers) do
    Enum.reduce(headers, conn, fn {k, v}, conn ->
      put_resp_header(conn, k, v)
    end)
  end

  defp build_req_headers(headers, opts) do
Maksim's avatar
Maksim committed
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
    headers
    |> downcase_headers()
    |> Enum.filter(fn {k, _} -> k in @keep_req_headers end)
    |> (fn headers ->
          headers = headers ++ Keyword.get(opts, :req_headers, [])

          if Keyword.get(opts, :keep_user_agent, false) do
            List.keystore(
              headers,
              "user-agent",
              0,
              {"user-agent", Pleroma.Application.user_agent()}
            )
          else
            headers
          end
        end).()
href's avatar
href committed
262
263
264
  end

  defp build_resp_headers(headers, opts) do
href's avatar
href committed
265
266
267
268
269
    headers
    |> Enum.filter(fn {k, _} -> k in @keep_resp_headers end)
    |> build_resp_cache_headers(opts)
    |> build_resp_content_disposition_header(opts)
    |> (fn headers -> headers ++ Keyword.get(opts, :resp_headers, []) end).()
href's avatar
href committed
270
271
  end

Maksim's avatar
Maksim committed
272
  defp build_resp_cache_headers(headers, _opts) do
href's avatar
href committed
273
274
275
276
277
278
279
280
281
282
283
284
    has_cache? = Enum.any?(headers, fn {k, _} -> k in @resp_cache_headers end)

    if has_cache? do
      headers
    else
      List.keystore(headers, "cache-control", 0, {"cache-control", @default_cache_control_header})
    end
  end

  defp build_resp_content_disposition_header(headers, opts) do
    opt = Keyword.get(opts, :inline_content_types, @inline_content_types)

285
    content_type = get_content_type(headers)
href's avatar
href committed
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301

    attachment? =
      cond do
        is_list(opt) && !Enum.member?(opt, content_type) -> true
        opt == false -> true
        true -> false
      end

    if attachment? do
      disposition = "attachment; filename=" <> Keyword.get(opts, :attachment_name, "attachment")
      List.keystore(headers, "content-disposition", 0, {"content-disposition", disposition})
    else
      headers
    end
  end

href's avatar
href committed
302
  defp header_length_constraint(headers, limit) when is_integer(limit) and limit > 0 do
href's avatar
href committed
303
304
305
306
307
308
309
310
311
312
313
314
315
    with {_, size} <- List.keyfind(headers, "content-length", 0),
         {size, _} <- Integer.parse(size),
         true <- size <= limit do
      :ok
    else
      false ->
        {:error, :body_too_large}

      _ ->
        :ok
    end
  end

href's avatar
href committed
316
  defp header_length_constraint(_, _), do: :ok
href's avatar
href committed
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344

  defp body_size_constraint(size, limit) when is_integer(limit) and limit > 0 and size >= limit do
    {:error, :body_too_large}
  end

  defp body_size_constraint(_, _), do: :ok

  defp check_read_duration(duration, max)
       when is_integer(duration) and is_integer(max) and max > 0 do
    if duration > max do
      {:error, :read_duration_exceeded}
    else
      {:ok, {duration, :erlang.system_time(:millisecond)}}
    end
  end

  defp check_read_duration(_, _), do: {:ok, :no_duration_limit, :no_duration_limit}

  defp increase_read_duration({previous_duration, started})
       when is_integer(previous_duration) and is_integer(started) do
    duration = :erlang.system_time(:millisecond) - started
    {:ok, previous_duration + duration}
  end

  defp increase_read_duration(_) do
    {:ok, :no_duration_limit, :no_duration_limit}
  end
end