honkoma/lib/pleroma/web/media_proxy/media_proxy.ex

71 lines
1.8 KiB
Elixir

# 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])
base64 = Base.url_encode64(url, @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
end