1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
|
# 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
import Pleroma.Web.Gettext
alias Calendar.DateTime
alias Plug.Crypto.KeyGenerator
alias Plug.Crypto.MessageEncryptor
use GenServer
@doc false
def start_link(_) do
GenServer.start_link(__MODULE__, [], name: __MODULE__)
end
@doc false
def init(_) do
{:ok, nil}
end
@doc """
Ask the configured captcha service for a new captcha
"""
def new do
GenServer.call(__MODULE__, :new)
end
@doc """
Ask the configured captcha service to validate the captcha
"""
def validate(token, captcha, answer_data) do
GenServer.call(__MODULE__, {:validate, token, captcha, answer_data})
end
@doc false
def handle_call(:new, _from, state) do
enabled = Pleroma.Config.get([__MODULE__, :enabled])
if !enabled do
{:reply, %{type: :none}, state}
else
new_captcha = method().new()
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")
# 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)
{
:reply,
# Replace the answer with the encrypted answer
%{new_captcha | answer_data: encrypted_captcha_answer},
state
}
end
end
@doc false
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")
# 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 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
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
{:reply, result, state}
end
defp method, do: Pleroma.Config.get!([__MODULE__, :method])
end
|
