xref: /webtrees/app/Services/RateLimitService.php (revision 9ed332c7e150b010efb7bb4244cb1f8ef3e2f5dc) 
1<?php
2
3/**
4 * webtrees: online genealogy
5 * Copyright (C) 2021 webtrees development team
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program. If not, see <https://www.gnu.org/licenses/>.
16 */
17
18declare(strict_types=1);
19
20namespace Fisharebest\Webtrees\Services;
21
22use Fisharebest\Webtrees\Contracts\UserInterface;
23use Fisharebest\Webtrees\Http\Exceptions\HttpTooManyRequestsException;
24use Fisharebest\Webtrees\Site;
25use LogicException;
26
27use function array_filter;
28use function explode;
29use function intdiv;
30use function strlen;
31use function time;
32
33/**
34 * Throttle events to prevent abuse.
35 */
36class RateLimitService
37{
38    private int $now;
39
40    /**
41     *
42     */
43    public function __construct()
44    {
45        $this->now = time();
46    }
47
48    /**
49     * Rate limit for actions related to a user, such as password reset request.
50     * Allow $num requests every $seconds
51     *
52     * @param int    $num     allow this number of events
53     * @param int    $seconds in a rolling window of this number of seconds
54     * @param string $limit   name of limit to enforce
55     *
56     * @return void
57     */
58    public function limitRateForSite(int $num, int $seconds, string $limit): void
59    {
60        $history = Site::getPreference($limit);
61
62        $history = $this->checkLimitReached($num, $seconds, $history);
63
64        Site::setPreference($limit, $history);
65    }
66
67    /**
68     * Rate limit for actions related to a user, such as password reset request.
69     * Allow $num requests every $seconds
70     *
71     * @param UserInterface $user    limit events for this user
72     * @param int           $num     allow this number of events
73     * @param int           $seconds in a rolling window of this number of seconds
74     * @param string        $limit   name of limit to enforce
75     *
76     * @return void
77     */
78    public function limitRateForUser(UserInterface $user, int $num, int $seconds, string $limit): void
79    {
80        $history = $user->getPreference($limit);
81
82        $history = $this->checkLimitReached($num, $seconds, $history);
83
84        $user->setPreference($limit, $history);
85    }
86
87    /**
88     * Rate limit - allow $num requests every $seconds
89     *
90     * @param int    $num     allow this number of events
91     * @param int    $seconds in a rolling window of this number of seconds
92     * @param string $history comma-separated list of previous timestamps
93     *
94     * @return string updated list of timestamps
95     * @throws HttpTooManyRequestsException
96     */
97    private function checkLimitReached(int $num, int $seconds, string $history): string
98    {
99        // Make sure we can store enough previous timestamps in a database field.
100        $max = intdiv(256, strlen($this->now . ','));
101        if ($num > $max) {
102            throw new LogicException('Cannot store ' . $num . ' previous events in the database');
103        }
104
105        // Extract the timestamps.
106        $timestamps = array_filter(explode(',', $history));
107
108        // Filter events within our time window.
109        $filter    = fn(string $x): bool => (int) $x >= $this->now - $seconds && (int) $x <= $this->now;
110        $in_window = array_filter($timestamps, $filter);
111
112        if (count($in_window) >= $num) {
113            throw new HttpTooManyRequestsException();
114        }
115
116        $timestamps[] = (string) $this->now;
117
118        while (count($timestamps) > $max) {
119            array_shift($timestamps);
120        }
121
122        return implode(',', $timestamps);
123    }
124}
125