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- # Pleroma: A lightweight social networking server
- # Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
- # SPDX-License-Identifier: AGPL-3.0-only
-
- defmodule Pleroma.Web.MediaProxy do
- alias Pleroma.Config
- alias Pleroma.Helpers.UriHelper
- alias Pleroma.Upload
- alias Pleroma.Web.Endpoint
- alias Pleroma.Web.MediaProxy.Invalidation
-
- @base64_opts [padding: false]
- @cache_table :banned_urls_cache
-
- @cachex Pleroma.Config.get([:cachex, :provider], Cachex)
-
- def cache_table, do: @cache_table
-
- @spec in_banned_urls(String.t()) :: boolean()
- def in_banned_urls(url), do: elem(@cachex.exists?(@cache_table, url(url)), 1)
-
- def remove_from_banned_urls(urls) when is_list(urls) do
- @cachex.execute!(@cache_table, fn cache ->
- Enum.each(Invalidation.prepare_urls(urls), &@cachex.del(cache, &1))
- end)
- end
-
- def remove_from_banned_urls(url) when is_binary(url) do
- @cachex.del(@cache_table, url(url))
- end
-
- def put_in_banned_urls(urls) when is_list(urls) do
- @cachex.execute!(@cache_table, fn cache ->
- Enum.each(Invalidation.prepare_urls(urls), &@cachex.put(cache, &1, true))
- end)
- end
-
- def put_in_banned_urls(url) when is_binary(url) do
- @cachex.put(@cache_table, url(url), true)
- end
-
- def url(url) when is_nil(url) or url == "", do: nil
- def url("/" <> _ = url), do: url
-
- def url(url) do
- if enabled?() and url_proxiable?(url) do
- encode_url(url)
- else
- url
- end
- end
-
- @spec url_proxiable?(String.t()) :: boolean()
- def url_proxiable?(url) do
- not local?(url) and not whitelisted?(url)
- end
-
- def preview_url(url, preview_params \\ []) do
- if preview_enabled?() do
- encode_preview_url(url, preview_params)
- else
- url(url)
- end
- end
-
- def enabled?, do: Config.get([:media_proxy, :enabled], false)
-
- # Note: media proxy must be enabled for media preview proxy in order to load all
- # non-local non-whitelisted URLs through it and be sure that body size constraint is preserved.
- def preview_enabled?, do: enabled?() and !!Config.get([:media_preview_proxy, :enabled])
-
- def local?(url), do: String.starts_with?(url, Endpoint.url())
-
- def whitelisted?(url) do
- %{host: domain} = URI.parse(url)
-
- mediaproxy_whitelist_domains =
- [:media_proxy, :whitelist]
- |> Config.get()
- |> Kernel.++(["#{Upload.base_url()}"])
- |> Enum.map(&maybe_get_domain_from_url/1)
-
- domain in mediaproxy_whitelist_domains
- end
-
- defp maybe_get_domain_from_url("http" <> _ = url) do
- URI.parse(url).host
- end
-
- defp maybe_get_domain_from_url(domain), do: domain
-
- defp base64_sig64(url) do
- base64 = Base.url_encode64(url, @base64_opts)
-
- sig64 =
- base64
- |> signed_url()
- |> Base.url_encode64(@base64_opts)
-
- {base64, sig64}
- end
-
- def encode_url(url) do
- {base64, sig64} = base64_sig64(url)
-
- build_url(sig64, base64, filename(url))
- end
-
- def encode_preview_url(url, preview_params \\ []) do
- {base64, sig64} = base64_sig64(url)
-
- build_preview_url(sig64, base64, filename(url), preview_params)
- end
-
- def decode_url(sig, url) do
- with {:ok, sig} <- Base.url_decode64(sig, @base64_opts),
- signature when signature == sig <- signed_url(url) do
- {:ok, Base.url_decode64!(url, @base64_opts)}
- else
- _ -> {:error, :invalid_signature}
- end
- end
-
- def decode_url(encoded) do
- [_, "proxy", sig, base64 | _] = URI.parse(encoded).path |> String.split("/")
- decode_url(sig, base64)
- end
-
- defp signed_url(url) do
- :crypto.mac(:hmac, :sha, Config.get([Endpoint, :secret_key_base]), url)
- end
-
- def filename(url_or_path) do
- if path = URI.parse(url_or_path).path, do: Path.basename(path)
- end
-
- def base_url do
- Config.get([:media_proxy, :base_url], Endpoint.url())
- end
-
- defp proxy_url(path, sig_base64, url_base64, filename) do
- [
- base_url(),
- path,
- sig_base64,
- url_base64,
- filename
- ]
- |> Enum.filter(& &1)
- |> Path.join()
- end
-
- def build_url(sig_base64, url_base64, filename \\ nil) do
- proxy_url("proxy", sig_base64, url_base64, filename)
- end
-
- def build_preview_url(sig_base64, url_base64, filename \\ nil, preview_params \\ []) do
- uri = proxy_url("proxy/preview", sig_base64, url_base64, filename)
-
- UriHelper.modify_uri_params(uri, preview_params)
- end
-
- def verify_request_path_and_url(
- %Plug.Conn{params: %{"filename" => _}, request_path: request_path},
- url
- ) do
- verify_request_path_and_url(request_path, url)
- end
-
- def verify_request_path_and_url(request_path, url) when is_binary(request_path) do
- filename = filename(url)
-
- if filename && not basename_matches?(request_path, filename) do
- {:wrong_filename, filename}
- else
- :ok
- end
- end
-
- def verify_request_path_and_url(_, _), do: :ok
-
- defp basename_matches?(path, filename) do
- basename = Path.basename(path)
- basename == filename or URI.decode(basename) == filename or URI.encode(basename) == filename
- end
- end
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