# Pleroma: A lightweight social networking server # Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/> # SPDX-License-Identifier: AGPL-3.0-only defmodule Pleroma.Web.MediaProxy do @base64_opts [padding: false] def url(nil), do: nil def url(""), do: nil def url("/" <> _ = url), do: url def url(url) do if !enabled?() or local?(url) or whitelisted?(url) do url else encode_url(url) end end defp enabled?, do: Pleroma.Config.get([:media_proxy, :enabled], false) defp local?(url), do: String.starts_with?(url, Pleroma.Web.base_url()) defp whitelisted?(url) do %{host: domain} = URI.parse(url) Enum.any?(Pleroma.Config.get([:media_proxy, :whitelist]), fn pattern -> String.equivalent?(domain, pattern) end) end def encode_url(url) do secret = Pleroma.Config.get([Pleroma.Web.Endpoint, :secret_key_base]) # Must preserve `%2F` for compatibility with S3 # https://git.pleroma.social/pleroma/pleroma/issues/580 replacement = get_replacement(url, ":2F:") # The URL is url-decoded and encoded again to ensure it is correctly encoded and not twice. base64 = url |> String.replace("%2F", replacement) |> URI.decode() |> URI.encode() |> String.replace(replacement, "%2F") |> Base.url_encode64(@base64_opts) sig = :crypto.hmac(:sha, secret, base64) sig64 = sig |> Base.url_encode64(@base64_opts) build_url(sig64, base64, filename(url)) end def decode_url(sig, url) do secret = Pleroma.Config.get([Pleroma.Web.Endpoint, :secret_key_base]) sig = Base.url_decode64!(sig, @base64_opts) local_sig = :crypto.hmac(:sha, secret, url) if local_sig == sig do {:ok, Base.url_decode64!(url, @base64_opts)} else {:error, :invalid_signature} end end def filename(url_or_path) do if path = URI.parse(url_or_path).path, do: Path.basename(path) end def build_url(sig_base64, url_base64, filename \\ nil) do [ Pleroma.Config.get([:media_proxy, :base_url], Pleroma.Web.base_url()), "proxy", sig_base64, url_base64, filename ] |> Enum.filter(fn value -> value end) |> Path.join() end defp get_replacement(url, replacement) do if String.contains?(url, replacement) do get_replacement(url, replacement <> replacement) else replacement end end end