forked from mirrors/akkoma
103 lines
3.2 KiB
Elixir
103 lines
3.2 KiB
Elixir
# Pleroma: A lightweight social networking server
|
|
# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
|
|
# SPDX-License-Identifier: AGPL-3.0-only
|
|
|
|
defmodule Pleroma.Captcha do
|
|
alias Calendar.DateTime
|
|
alias Plug.Crypto.KeyGenerator
|
|
alias Plug.Crypto.MessageEncryptor
|
|
|
|
@doc """
|
|
Ask the configured captcha service for a new captcha
|
|
"""
|
|
def new do
|
|
if not enabled?() do
|
|
%{type: :none}
|
|
else
|
|
new_captcha = method().new()
|
|
|
|
# This make salt a little different for two keys
|
|
{secret, sign_secret} = secret_pair(new_captcha[:token])
|
|
|
|
# Basically 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)
|
|
|
|
# Replace the answer with the encrypted answer
|
|
%{new_captcha | answer_data: encrypted_captcha_answer}
|
|
end
|
|
end
|
|
|
|
@doc """
|
|
Ask the configured captcha service to validate the captcha
|
|
"""
|
|
def validate(token, captcha, answer_data) do
|
|
with {:ok, %{at: at, answer_data: answer_md5}} <- validate_answer_data(token, answer_data),
|
|
:ok <- validate_expiration(at),
|
|
:ok <- validate_usage(token),
|
|
:ok <- method().validate(token, captcha, answer_md5),
|
|
{:ok, _} <- mark_captcha_as_used(token) do
|
|
:ok
|
|
end
|
|
end
|
|
|
|
def enabled?, do: Pleroma.Config.get([__MODULE__, :enabled], false)
|
|
|
|
defp seconds_valid, do: Pleroma.Config.get!([__MODULE__, :seconds_valid])
|
|
|
|
defp secret_pair(token) 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")
|
|
|
|
{secret, sign_secret}
|
|
end
|
|
|
|
defp validate_answer_data(token, answer_data) do
|
|
{secret, sign_secret} = secret_pair(token)
|
|
|
|
with false <- is_nil(answer_data),
|
|
{:ok, data} <- MessageEncryptor.decrypt(answer_data, secret, sign_secret),
|
|
%{at: at, answer_data: answer_md5} <- :erlang.binary_to_term(data) do
|
|
{:ok, %{at: at, answer_data: answer_md5}}
|
|
else
|
|
_ -> {:error, :invalid_answer_data}
|
|
end
|
|
end
|
|
|
|
defp validate_expiration(created_at) do
|
|
# 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
|
|
|
|
valid_if_after = DateTime.subtract!(DateTime.now_utc(), seconds_valid())
|
|
|
|
if DateTime.before?(created_at, valid_if_after) do
|
|
{:error, :expired}
|
|
else
|
|
:ok
|
|
end
|
|
end
|
|
|
|
defp validate_usage(token) do
|
|
if is_nil(Cachex.get!(:used_captcha_cache, token)) do
|
|
:ok
|
|
else
|
|
{:error, :already_used}
|
|
end
|
|
end
|
|
|
|
defp mark_captcha_as_used(token) do
|
|
ttl = seconds_valid() |> :timer.seconds()
|
|
Cachex.put(:used_captcha_cache, token, true, ttl: ttl)
|
|
end
|
|
|
|
defp method, do: Pleroma.Config.get!([__MODULE__, :method])
|
|
end
|