+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
defmodule Pleroma.Captcha do
- use GenServer
+ import Pleroma.Web.Gettext
- @ets_options [:ordered_set, :private, :named_table, {:read_concurrency, true}]
+ alias Calendar.DateTime
+ alias Plug.Crypto.KeyGenerator
+ alias Plug.Crypto.MessageEncryptor
+
+ use GenServer
@doc false
- def start_link() do
+ def start_link(_) do
GenServer.start_link(__MODULE__, [], name: __MODULE__)
end
@doc false
def init(_) do
- # Create a ETS table to store captchas
- ets_name = Module.concat(method(), Ets)
- ^ets_name = :ets.new(Module.concat(method(), Ets), @ets_options)
-
{:ok, nil}
end
@doc """
Ask the configured captcha service for a new captcha
"""
- def new() do
+ def new do
GenServer.call(__MODULE__, :new)
end
@doc """
Ask the configured captcha service to validate the captcha
"""
- def validate(token, captcha) do
- GenServer.call(__MODULE__, {:validate, token, captcha})
+ def validate(token, captcha, answer_data) do
+ GenServer.call(__MODULE__, {:validate, token, captcha, answer_data})
end
@doc false
else
new_captcha = method().new()
- seconds_retained = Pleroma.Config.get!([__MODULE__, :seconds_retained])
- # Wait several minutes and if the captcha is still there, delete it
- Process.send_after(self(), {:cleanup, new_captcha.token}, 1000 * seconds_retained)
+ secret_key_base = Pleroma.Config.get!([Pleroma.Web.Endpoint, :secret_key_base])
+
+ # This make salt a little different for two keys
+ token = new_captcha[:token]
+ secret = KeyGenerator.generate(secret_key_base, token <> "_encrypt")
+ sign_secret = KeyGenerator.generate(secret_key_base, token <> "_sign")
+ # Basicallty copy what Phoenix.Token does here, add the time to
+ # the actual data and make it a binary to then encrypt it
+ encrypted_captcha_answer =
+ %{
+ at: DateTime.now_utc(),
+ answer_data: new_captcha[:answer_data]
+ }
+ |> :erlang.term_to_binary()
+ |> MessageEncryptor.encrypt(secret, sign_secret)
- {:reply, new_captcha, state}
+ {
+ :reply,
+ # Repalce the answer with the encrypted answer
+ %{new_captcha | answer_data: encrypted_captcha_answer},
+ state
+ }
end
end
@doc false
- def handle_call({:validate, token, captcha}, _from, state) do
- {:reply, method().validate(token, captcha), state}
- end
+ def handle_call({:validate, token, captcha, answer_data}, _from, state) do
+ secret_key_base = Pleroma.Config.get!([Pleroma.Web.Endpoint, :secret_key_base])
+ secret = KeyGenerator.generate(secret_key_base, token <> "_encrypt")
+ sign_secret = KeyGenerator.generate(secret_key_base, token <> "_sign")
- @doc false
- def handle_info({:cleanup, token}, state) do
- method().cleanup(token)
+ # If the time found is less than (current_time-seconds_valid) then the time has already passed
+ # Later we check that the time found is more than the presumed invalidatation time, that means
+ # that the data is still valid and the captcha can be checked
+ seconds_valid = Pleroma.Config.get!([Pleroma.Captcha, :seconds_valid])
+ valid_if_after = DateTime.subtract!(DateTime.now_utc(), seconds_valid)
+
+ result =
+ with {:ok, data} <- MessageEncryptor.decrypt(answer_data, secret, sign_secret),
+ %{at: at, answer_data: answer_md5} <- :erlang.binary_to_term(data) do
+ try do
+ if DateTime.before?(at, valid_if_after),
+ do: throw({:error, dgettext("errors", "CAPTCHA expired")})
+
+ if not is_nil(Cachex.get!(:used_captcha_cache, token)),
+ do: throw({:error, dgettext("errors", "CAPTCHA already used")})
+
+ res = method().validate(token, captcha, answer_md5)
+ # Throw if an error occurs
+ if res != :ok, do: throw(res)
+
+ # Mark this captcha as used
+ {:ok, _} =
+ Cachex.put(:used_captcha_cache, token, true, ttl: :timer.seconds(seconds_valid))
+
+ :ok
+ catch
+ :throw, e -> e
+ end
+ else
+ _ -> {:error, dgettext("errors", "Invalid answer data")}
+ end
- {:noreply, state}
+ {:reply, result, state}
end
defp method, do: Pleroma.Config.get!([__MODULE__, :method])