pleroma/lib/pleroma/reverse_proxy.ex
moon.eth b11e8888d1 MediaProxy: improve inline rendering of remote image attachments
Two related changes that ensure remote images render inline in timelines
instead of as clickable links.

reverse_proxy: always force inline for whitelisted content types
  When `inline_content_types` is configured as a whitelist, the upstream's
  `content-disposition` header used to be passed through unchanged. Some
  origins send `content-disposition: attachment` for media we want
  embedded, so the proxy now always emits `content-disposition: inline`
  for whitelisted types (overriding the upstream header), deriving a
  filename from `MIME.extensions/1` (e.g. `inline.gif`) so browsers have
  something to use for "Save As". When the type has no known extension,
  the bare token `inline` is emitted. The `inline_content_types: true`
  (pass-through) and `:false` (always attachment) behaviours are
  unchanged.

ActivityPub: sniff MIME type for extensionless/generic attachments
  Some remotes (e.g. extensionless Cloudflare Images URLs) ship
  attachments with no usable `mediaType` (missing, empty, or
  `application/octet-stream`), which would render as links instead of
  inline images. `AttachmentValidator.fix_media_type/1` now fetches the
  first 8 KB of the URL and runs it through libmagic when the declared
  type carries no real information. Only `image/*` results replace the
  declared type; any other result, non-2xx response, transport error, or
  exception yields `nil` and the original type is kept, so ingestion
  never blocks and non-image media is never reclassified. Present real
  types are left untouched (no fetch is attempted).

The new logic lives in `Pleroma.Web.ActivityPub.ObjectValidators.AttachmentTypeSniffer`.

Tests: comprehensive coverage of both changes, including a dedicated
suite for the sniffer covering happy paths, non-image bodies, HTTP
failures, raised exceptions, guard clauses, and verification that the
Range header is sent; AttachmentValidator tests for mimeType fallback,
empty-string mediaType, multi-URL sniffing, and HTTP-failure fallback;
ReverseProxy tests for inline_content_types `true`/`false`/custom
whitelists, bare-inline for types without a MIME extension, and
attachment_name handling.
2026-07-14 15:04:06 +09:00

493 lines
15 KiB
Elixir

# Pleroma: A lightweight social networking server
# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.ReverseProxy do
alias Pleroma.Utils.URIEncoding
@range_headers ~w(range if-range)
@keep_req_headers ~w(accept accept-encoding cache-control if-modified-since) ++
~w(if-unmodified-since if-none-match) ++ @range_headers
@resp_cache_headers ~w(etag date last-modified)
@keep_resp_headers @resp_cache_headers ++
~w(content-length content-type content-disposition content-encoding) ++
~w(content-range accept-ranges vary)
@default_cache_control_header "public, max-age=1209600, immutable"
@valid_resp_codes [200, 206, 304]
@max_read_duration :timer.seconds(30)
@max_body_length :infinity
@failed_request_ttl :timer.seconds(60)
@methods ~w(GET HEAD)
@allowed_mime_types Pleroma.Config.get([Pleroma.Upload, :allowed_mime_types], [])
@cachex Pleroma.Config.get([:cachex, :provider], Cachex)
def max_read_duration_default, do: @max_read_duration
def default_cache_control_header, do: @default_cache_control_header
@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)}`
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.
* `failed_request_ttl` (default `#{inspect(@failed_request_ttl)}` ms): the time the failed request is cached and cannot be retried.
* `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 for which `content-disposition: inline`
is always set (overriding any upstream header) so the media can be embedded
in pages; the filename is derived from the content type
* `req_headers`, `resp_headers` additional headers.
* `http`: options for [hackney](https://github.com/benoitc/hackney) or [gun](https://github.com/ninenines/gun).
"""
@default_options [pool: :media]
@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() ::
{:max_read_duration, non_neg_integer() | :infinity}
| {:max_body_length, non_neg_integer() | :infinity}
| {:failed_request_ttl, non_neg_integer() | :infinity}
| {:http, keyword()}
| {:req_headers, [{String.t(), String.t()}]}
| {:resp_headers, [{String.t(), String.t()}]}
| {:inline_content_types, boolean() | list(String.t())}
| {:redirect_on_failure, boolean()}
@spec call(Plug.Conn.t(), String.t(), list(option())) :: Plug.Conn.t()
def call(_conn, _url, _opts \\ [])
def call(conn = %{method: method}, url, opts) when method in @methods do
client_opts = Keyword.merge(@default_options, Keyword.get(opts, :http, []))
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, nil} <- @cachex.get(:failed_proxy_url_cache, url),
{:ok, code, headers, client} <- request(method, url, req_headers, client_opts),
:ok <-
header_length_constraint(
headers,
Keyword.get(opts, :max_body_length, @max_body_length)
) do
response(conn, client, url, code, headers, opts)
else
{:ok, true} ->
conn
|> error_or_redirect(url, 500, "Request failed", opts)
|> halt()
{: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}")
track_failed_url(url, code, opts)
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)}")
track_failed_url(url, error, opts)
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, opts) do
method = method |> String.downcase() |> String.to_existing_atom()
url = maybe_encode_url(url)
Logger.debug("#{__MODULE__} #{method} #{url} #{inspect(headers)}")
case client().request(method, url, headers, "", 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}}
{:ok, code, _} ->
{:error, {:invalid_http_response, code}}
{:error, error} ->
{:error, error}
end
end
defp response(conn, client, url, status, headers, opts) do
Logger.debug("#{__MODULE__} #{status} #{url} #{inspect(headers)}")
result =
conn
|> put_resp_headers(build_resp_headers(headers, opts))
|> streaming_compat
|> send_chunked(status)
|> chunk_reply(client, opts)
case result do
{:ok, conn} ->
halt(conn)
{:error, :closed, conn} ->
client().close(client)
halt(conn)
{:error, error, conn} ->
Logger.warning(
"#{__MODULE__} request to #{url} failed while reading/chunking: #{inspect(error)}"
)
client().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, client} <- client().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_length, @max_body_length)
),
{: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
Logger.debug("#{__MODULE__} #{code} #{url} #{inspect(headers)}")
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
defp get_content_type(headers) do
{_, content_type} =
List.keyfind(headers, "content-type", 0, {"content-type", "application/octet-stream"})
[content_type | _] = String.split(content_type, ";")
content_type
end
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
headers
|> downcase_headers()
|> Enum.filter(fn {k, _} -> k in @keep_req_headers end)
|> build_req_range_or_encoding_header(opts)
|> build_req_user_agent_header(opts)
|> Keyword.merge(Keyword.get(opts, :req_headers, []))
end
# Disable content-encoding if any @range_headers are requested (see #1823).
defp build_req_range_or_encoding_header(headers, _opts) do
range? = Enum.any?(headers, fn {header, _} -> Enum.member?(@range_headers, header) end)
if range? && List.keymember?(headers, "accept-encoding", 0) do
List.keydelete(headers, "accept-encoding", 0)
else
headers
end
end
defp build_req_user_agent_header(headers, _opts) do
List.keystore(
headers,
"user-agent",
0,
{"user-agent", Pleroma.Application.user_agent()}
)
end
defp build_resp_headers(headers, opts) do
headers
|> Enum.filter(fn {k, _} -> k in @keep_resp_headers end)
|> build_resp_cache_headers(opts)
|> sanitise_content_type()
|> build_resp_content_disposition_header(opts)
|> Keyword.merge(Keyword.get(opts, :resp_headers, []))
end
defp sanitise_content_type(headers) do
original_ct = get_content_type(headers)
safe_ct =
Pleroma.Web.Plugs.Utils.get_safe_mime_type(
%{allowed_mime_types: @allowed_mime_types},
original_ct
)
[
{"content-type", safe_ct}
| Enum.filter(headers, fn {k, _v} -> k != "content-type" end)
]
end
defp build_resp_cache_headers(headers, _opts) do
has_cache? = Enum.any?(headers, fn {k, _} -> k in @resp_cache_headers end)
cond do
has_cache? ->
# There's caching header present but no cache-control -- we need to set our own
# as Plug defaults to "max-age=0, private, must-revalidate"
List.keystore(
headers,
"cache-control",
0,
{"cache-control", @default_cache_control_header}
)
true ->
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)
content_type = get_content_type(headers)
attachment? =
cond do
is_list(opt) && !Enum.member?(opt, content_type) -> true
opt == false -> true
true -> false
end
if attachment? do
name =
try do
{{"content-disposition", content_disposition_string}, _} =
List.keytake(headers, "content-disposition", 0)
[name | _] =
Regex.run(
~r/filename="((?:[^"\\]|\\.)*)"/u,
content_disposition_string || "",
capture: :all_but_first
)
name
rescue
MatchError -> Keyword.get(opts, :attachment_name, "attachment")
end
disposition = "attachment; filename=\"#{name}\""
List.keystore(headers, "content-disposition", 0, {"content-disposition", disposition})
else
if opt == true do
headers
else
name = inline_filename(content_type)
disposition =
if name do
"inline; filename=\"#{name}\""
else
"inline"
end
List.keystore(headers, "content-disposition", 0, {"content-disposition", disposition})
end
end
end
defp inline_filename(content_type) do
case MIME.extensions(content_type) do
[ext | _] when ext != "" -> "inline.#{ext}"
_ -> nil
end
end
defp header_length_constraint(headers, limit) when is_integer(limit) and limit > 0 do
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
defp header_length_constraint(_, _), do: :ok
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 client, do: Pleroma.ReverseProxy.Client.Wrapper
defp track_failed_url(url, error, opts) do
ttl =
unless error in [:body_too_large, 400, 204] do
Keyword.get(opts, :failed_request_ttl, @failed_request_ttl)
else
nil
end
@cachex.put(:failed_proxy_url_cache, url, true, ttl: ttl)
end
# When Cowboy handles a chunked response with a content-length header it streams
# over HTTP 1.1 instead of chunking. Bandit cannot stream over HTTP 1.1 so the header
# must be stripped or it breaks RFC compliance for Transfer Encoding: Chunked. RFC9112§6.2
#
# HTTP2 is always streamed for all adapters.
defp streaming_compat(conn) do
with Phoenix.Endpoint.Cowboy2Adapter <- Pleroma.Web.Endpoint.config(:adapter) do
conn
else
_ -> delete_resp_header(conn, "content-length")
end
end
# Only when Tesla adapter is Hackney or Finch does the URL
# need encoding before Reverse Proxying as both end up
# using the raw Hackney client and cannot leverage our
# EncodeUrl Tesla middleware
# Also do it for test environment
defp maybe_encode_url(url) do
case Application.get_env(:tesla, :adapter) do
Tesla.Adapter.Hackney -> URIEncoding.encode_url(url)
{Tesla.Adapter.Finch, _} -> URIEncoding.encode_url(url)
Tesla.Mock -> URIEncoding.encode_url(url)
_ -> url
end
end
end