xref: /webtrees/app/Http/Middleware/BadBotBlocker.php (revision f3d48b691701b372cb536390c0aa5fb478936015) 
1<?php
2
3/**
4 * webtrees: online genealogy
5 * Copyright (C) 2022 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\Http\Middleware;
21
22use Fig\Http\Message\StatusCodeInterface;
23use Fisharebest\Webtrees\Registry;
24use Fisharebest\Webtrees\Validator;
25use GuzzleHttp\Client;
26use GuzzleHttp\Exception\GuzzleException;
27use Iodev\Whois\Loaders\CurlLoader;
28use Iodev\Whois\Modules\Asn\AsnRouteInfo;
29use Iodev\Whois\Whois;
30use IPLib\Address\AddressInterface;
31use IPLib\Factory as IPFactory;
32use IPLib\Range\RangeInterface;
33use Psr\Http\Message\ResponseInterface;
34use Psr\Http\Message\ServerRequestInterface;
35use Psr\Http\Server\MiddlewareInterface;
36use Psr\Http\Server\RequestHandlerInterface;
37use Throwable;
38
39use function array_filter;
40use function array_map;
41use function assert;
42use function gethostbyaddr;
43use function gethostbyname;
44use function preg_match_all;
45use function random_int;
46use function response;
47use function str_contains;
48use function str_ends_with;
49
50/**
51 * Middleware to block bad robots before they waste our valuable CPU cycles.
52 */
53class BadBotBlocker implements MiddlewareInterface
54{
55    private const REGEX_OCTET = '(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)';
56    private const REGEX_IPV4  = '/\\b' . self::REGEX_OCTET . '(?:\\.' . self::REGEX_OCTET . '){3}\\b/';
57
58    // Cache whois requests.  Try to avoid all caches expiring at the same time.
59    private const WHOIS_TTL_MIN = 28 * 86400;
60    private const WHOIS_TTL_MAX = 35 * 86400;
61    private const WHOIS_TIMEOUT = 5;
62
63    // Bad robots - SEO optimisers, advertisers, etc.  This list is shared with robots.txt.
64    public const BAD_ROBOTS = [
65        'admantx',
66        'Adsbot',
67        'AhrefsBot',
68        'Amazonbot', // Until it understands crawl-delay and noindex / nofollow
69        'AspiegelBot',
70        'Barkrowler',
71        'BLEXBot',
72        'DataForSEO',
73        'DotBot',
74        'Grapeshot',
75        'Honolulu-bot', // Aggressive crawer, no info available
76        'ia_archiver',
77        'Linguee',
78        'MJ12bot',
79        'netEstate NE',
80        'panscient',
81        'PetalBot',
82        'proximic',
83        'SemrushBot',
84        'SEOkicks',
85        'SiteKiosk',
86        'Turnitin',
87        'XoviBot',
88        'ZoominfoBot',
89    ];
90
91    /**
92     * Some search engines use reverse/forward DNS to verify the IP address.
93     *
94     * @see https://developer.amazon.com/support/amazonbot
95     * @see https://support.google.com/webmasters/answer/80553?hl=en
96     * @see https://www.bing.com/webmaster/help/which-crawlers-does-bing-use-8c184ec0
97     * @see https://www.bing.com/webmaster/help/how-to-verify-bingbot-3905dc26
98     * @see https://yandex.com/support/webmaster/robot-workings/check-yandex-robots.html
99     * @see https://www.mojeek.com/bot.html
100     * @see https://support.apple.com/en-gb/HT204683
101     */
102    private const ROBOT_REV_FWD_DNS = [
103        'Amazonbot'   => ['.crawl.amazon.com'],
104        'Applebot'    => ['.applebot.apple.com'],
105        'bingbot'     => ['.search.msn.com'],
106        'BingPreview' => ['.search.msn.com'],
107        'Google'      => ['.google.com', '.googlebot.com'],
108        'MojeekBot'   => ['.mojeek.com'],
109        'Mail.RU_Bot' => ['.mail.ru'],
110        'msnbot'      => ['.search.msn.com'],
111        'Qwantify'    => ['.search.qwant.com'],
112        'Sogou'       => ['.crawl.sogou.com'],
113        'Yahoo'       => ['.crawl.yahoo.net'],
114        'Yandex'      => ['.yandex.ru', '.yandex.net', '.yandex.com'],
115    ];
116
117    /**
118     * Some search engines only use reverse DNS to verify the IP address.
119     *
120     * @see https://help.baidu.com/question?prod_id=99&class=0&id=3001
121     * @see https://napoveda.seznam.cz/en/full-text-search/seznambot-crawler
122     * @see https://www.ionos.de/terms-gtc/faq-crawler
123     */
124    private const ROBOT_REV_ONLY_DNS = [
125        'Baiduspider' => ['.baidu.com', '.baidu.jp'],
126        'FreshBot'    => ['.seznam.cz'],
127        'IonCrawl'    => ['.1und1.org'],
128        'Neevabot'    => ['.neeva.com'],
129    ];
130
131    /**
132     * Some search engines operate from designated IP addresses.
133     *
134     * @see https://www.apple.com/go/applebot
135     * @see https://help.duckduckgo.com/duckduckgo-help-pages/results/duckduckbot
136     */
137    private const ROBOT_IPS = [
138        'AppleBot'    => [
139            '17.0.0.0/8',
140        ],
141        'Ask Jeeves'  => [
142            '65.214.45.143',
143            '65.214.45.148',
144            '66.235.124.192',
145            '66.235.124.7',
146            '66.235.124.101',
147            '66.235.124.193',
148            '66.235.124.73',
149            '66.235.124.196',
150            '66.235.124.74',
151            '63.123.238.8',
152            '202.143.148.61',
153        ],
154        'DuckDuckBot' => [
155            '23.21.227.69',
156            '50.16.241.113',
157            '50.16.241.114',
158            '50.16.241.117',
159            '50.16.247.234',
160            '52.204.97.54',
161            '52.5.190.19',
162            '54.197.234.188',
163            '54.208.100.253',
164            '54.208.102.37',
165            '107.21.1.8',
166        ],
167    ];
168
169    /**
170     * Some search engines operate from designated IP addresses.
171     *
172     * @see https://bot.seekport.com/
173     */
174    private const ROBOT_IP_FILES = [
175        'SeekportBot' => 'https://bot.seekport.com/seekportbot_ips.txt',
176    ];
177
178    /**
179     * Some search engines operate from within a designated autonomous system.
180     *
181     * @see https://developers.facebook.com/docs/sharing/webmasters/crawler
182     * @see https://www.facebook.com/peering/
183     */
184    private const ROBOT_ASNS = [
185        'facebook' => ['AS32934', 'AS63293'],
186        'twitter'  => ['AS13414'],
187    ];
188
189    /**
190     * @param ServerRequestInterface  $request
191     * @param RequestHandlerInterface $handler
192     *
193     * @return ResponseInterface
194     */
195    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
196    {
197        $ua      = Validator::serverParams($request)->string('HTTP_USER_AGENT', '');
198        $ip      = Validator::attributes($request)->string('client-ip');
199        $address = IPFactory::parseAddressString($ip);
200        assert($address instanceof AddressInterface);
201
202        foreach (self::BAD_ROBOTS as $robot) {
203            if (str_contains($ua, $robot)) {
204                return $this->response();
205            }
206        }
207
208        foreach (self::ROBOT_REV_FWD_DNS as $robot => $valid_domains) {
209            if (str_contains($ua, $robot) && !$this->checkRobotDNS($ip, $valid_domains, false)) {
210                return $this->response();
211            }
212        }
213
214        foreach (self::ROBOT_REV_ONLY_DNS as $robot => $valid_domains) {
215            if (str_contains($ua, $robot) && !$this->checkRobotDNS($ip, $valid_domains, true)) {
216                return $this->response();
217            }
218        }
219
220        foreach (self::ROBOT_IPS as $robot => $valid_ip_ranges) {
221            if (str_contains($ua, $robot)) {
222                foreach ($valid_ip_ranges as $ip_range) {
223                    $range = IPFactory::parseRangeString($ip_range);
224
225                    if ($range instanceof RangeInterface && $range->contains($address)) {
226                        continue 2;
227                    }
228                }
229
230                return $this->response();
231            }
232        }
233
234        foreach (self::ROBOT_IP_FILES as $robot => $url) {
235            if (str_contains($ua, $robot)) {
236                $valid_ip_ranges = $this->fetchIpRangesForUrl($robot, $url);
237
238                foreach ($valid_ip_ranges as $ip_range) {
239                    $range = IPFactory::parseRangeString($ip_range);
240
241                    if ($range instanceof RangeInterface && $range->contains($address)) {
242                        continue 2;
243                    }
244                }
245
246                return $this->response();
247            }
248        }
249
250        foreach (self::ROBOT_ASNS as $robot => $asns) {
251            foreach ($asns as $asn) {
252                if (str_contains($ua, $robot)) {
253                    foreach ($this->fetchIpRangesForAsn($asn) as $range) {
254                        if ($range->contains($address)) {
255                            continue 2;
256                        }
257                    }
258
259                    return $this->response();
260                }
261            }
262        }
263
264        // Allow sites to block access from entire networks.
265        $block_asn = Validator::attributes($request)->string('block_asn', '');
266        preg_match_all('/(AS\d+)/', $block_asn, $matches);
267
268        foreach ($matches[1] as $asn) {
269            foreach ($this->fetchIpRangesForAsn($asn) as $range) {
270                if ($range->contains($address)) {
271                    return $this->response();
272                }
273            }
274        }
275
276        return $handler->handle($request);
277    }
278
279    /**
280     * Check that an IP address belongs to a robot operator using a forward/reverse DNS lookup.
281     *
282     * @param string        $ip
283     * @param array<string> $valid_domains
284     * @param bool          $reverse_only
285     *
286     * @return bool
287     */
288    private function checkRobotDNS(string $ip, array $valid_domains, bool $reverse_only): bool
289    {
290        $host = gethostbyaddr($ip);
291
292        if ($host === false) {
293            return false;
294        }
295
296        foreach ($valid_domains as $domain) {
297            if (str_ends_with($host, $domain)) {
298                return $reverse_only || $ip === gethostbyname($host);
299            }
300        }
301
302        return false;
303    }
304
305    /**
306     * Perform a whois search for an ASN.
307     *
308     * @param string $asn - The autonomous system number to query
309     *
310     * @return array<RangeInterface>
311     */
312    private function fetchIpRangesForAsn(string $asn): array
313    {
314        return Registry::cache()->file()->remember('whois-asn-' . $asn, static function () use ($asn): array {
315            $mapper = static fn (AsnRouteInfo $route_info): ?RangeInterface => IPFactory::parseRangeString($route_info->route ?: $route_info->route6);
316
317            try {
318                $loader = new CurlLoader(self::WHOIS_TIMEOUT);
319                $whois  = new Whois($loader);
320                $info   = $whois->loadAsnInfo($asn);
321                $routes = $info->routes;
322                $ranges = array_map($mapper, $routes);
323
324                return array_filter($ranges);
325            } catch (Throwable) {
326                return [];
327            }
328        }, random_int(self::WHOIS_TTL_MIN, self::WHOIS_TTL_MAX));
329    }
330
331    /**
332     * Fetch a list of IP addresses from a remote file.
333     *
334     * @param string $ua
335     * @param string $url
336     *
337     * @return array<string>
338     */
339    private function fetchIpRangesForUrl(string $ua, string $url): array
340    {
341        return Registry::cache()->file()->remember('url-ip-list-' . $ua, static function () use ($url): array {
342            try {
343                $client   = new Client();
344                $response = $client->get($url, ['timeout' => 5]);
345                $contents = $response->getBody()->getContents();
346
347                preg_match_all(self::REGEX_IPV4, $contents, $matches);
348
349                return $matches[0];
350            } catch (GuzzleException) {
351                return [];
352            }
353        }, random_int(self::WHOIS_TTL_MIN, self::WHOIS_TTL_MAX));
354    }
355
356    /**
357     * @return ResponseInterface
358     */
359    private function response(): ResponseInterface
360    {
361        return response('Not acceptable', StatusCodeInterface::STATUS_NOT_ACCEPTABLE);
362    }
363}
364