akkoma/lib/pleroma/web/media_proxy/controller.ex

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defmodule Pleroma.Web.MediaProxy.MediaProxyController do
use Pleroma.Web, :controller
require Logger
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@httpoison Application.get_env(:pleroma, :httpoison)
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@max_body_length 25 * 1_048_576
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@cache_control %{
default: "public, max-age=1209600",
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error: "public, must-revalidate, max-age=160"
}
# Content-types that will not be returned as content-disposition attachments
# Override with :media_proxy, :safe_content_types in the configuration
@safe_content_types [
"image/gif",
"image/jpeg",
"image/jpg",
"image/png",
"image/svg+xml",
"audio/mpeg",
"audio/mp3",
"video/webm",
"video/mp4"
]
def remote(conn, params = %{"sig" => sig, "url" => url}) do
config = Application.get_env(:pleroma, :media_proxy, [])
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with true <- Keyword.get(config, :enabled, false),
{:ok, url} <- Pleroma.Web.MediaProxy.decode_url(sig, url),
filename <- Path.basename(url),
true <-
if(Map.get(params, "filename"),
do: filename == Path.basename(conn.request_path),
else: true
),
{:ok, content_type, body} <- proxy_request(url),
safe_content_type <-
Enum.member?(
Keyword.get(config, :safe_content_types, @safe_content_types),
content_type
) do
conn
|> put_resp_content_type(content_type)
|> set_cache_header(:default)
|> put_resp_header(
"content-security-policy",
"default-src 'none'; style-src 'unsafe-inline'; media-src data:; img-src 'self' data:"
)
|> put_resp_header("x-xss-protection", "1; mode=block")
|> put_resp_header("x-content-type-options", "nosniff")
|> put_attachement_header(safe_content_type, filename)
|> send_resp(200, body)
else
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false ->
send_error(conn, 404)
{:error, :invalid_signature} ->
send_error(conn, 403)
{:error, {:http, _, url}} ->
redirect_or_error(conn, url, Keyword.get(config, :redirect_on_failure, true))
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end
end
defp proxy_request(link) do
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headers = [
{"user-agent",
"Pleroma/MediaProxy; #{Pleroma.Web.base_url()} <#{
Application.get_env(:pleroma, :instance)[:email]
}>"}
]
options =
@httpoison.process_request_options([:insecure, {:follow_redirect, true}]) ++
[{:pool, :default}]
with {:ok, 200, headers, client} <- :hackney.request(:get, link, headers, "", options),
headers = Enum.into(headers, Map.new()),
{:ok, body} <- proxy_request_body(client),
content_type <- proxy_request_content_type(headers, body) do
{:ok, content_type, body}
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else
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{:ok, status, _, _} ->
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Logger.warn("MediaProxy: request failed, status #{status}, link: #{link}")
{:error, {:http, :bad_status, link}}
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{:error, error} ->
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Logger.warn("MediaProxy: request failed, error #{inspect(error)}, link: #{link}")
{:error, {:http, error, link}}
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end
end
defp set_cache_header(conn, key) do
Plug.Conn.put_resp_header(conn, "cache-control", @cache_control[key])
end
defp redirect_or_error(conn, url, true), do: redirect(conn, external: url)
defp redirect_or_error(conn, url, _), do: send_error(conn, 502, "Media proxy error: " <> url)
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defp send_error(conn, code, body \\ "") do
conn
|> set_cache_header(:error)
|> send_resp(code, body)
end
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defp proxy_request_body(client), do: proxy_request_body(client, <<>>)
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defp proxy_request_body(client, body) when byte_size(body) < @max_body_length do
case :hackney.stream_body(client) do
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{:ok, data} -> proxy_request_body(client, <<body::binary, data::binary>>)
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:done -> {:ok, body}
{:error, reason} -> {:error, reason}
end
end
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defp proxy_request_body(client, _) do
:hackney.close(client)
{:error, :body_too_large}
end
# TODO: the body is passed here as well because some hosts do not provide a content-type.
# At some point we may want to use magic numbers to discover the content-type and reply a proper one.
defp proxy_request_content_type(headers, _body) do
headers["Content-Type"] || headers["content-type"] || "application/octet-stream"
end
defp put_attachement_header(conn, true, _), do: conn
defp put_attachement_header(conn, false, filename) do
put_resp_header(conn, "content-disposition", "attachment; filename='#{filename}'")
end
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end