xref: /webtrees/app/Http/Middleware/BadBotBlocker.php (revision 87380fa884f63642e77a891fd8b6744322c8f79f) 
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        'ia_archiver',
76        'Linguee',
77        'MJ12bot',
78        'netEstate NE',
79        'panscient',
80        'PetalBot',
81        'proximic',
82        'SemrushBot',
83        'SEOkicks',
84        'SiteKiosk',
85        'Turnitin',
86        'XoviBot',
87        'ZoominfoBot',
88    ];
89
90    /**
91     * Some search engines use reverse/forward DNS to verify the IP address.
92     *
93     * @see https://developer.amazon.com/support/amazonbot
94     * @see https://support.google.com/webmasters/answer/80553?hl=en
95     * @see https://www.bing.com/webmaster/help/which-crawlers-does-bing-use-8c184ec0
96     * @see https://www.bing.com/webmaster/help/how-to-verify-bingbot-3905dc26
97     * @see https://yandex.com/support/webmaster/robot-workings/check-yandex-robots.html
98     * @see https://www.mojeek.com/bot.html
99     * @see https://support.apple.com/en-gb/HT204683
100     */
101    private const ROBOT_REV_FWD_DNS = [
102        'Amazonbot'   => ['.crawl.amazon.com'],
103        'Applebot'    => ['.applebot.apple.com'],
104        'bingbot'     => ['.search.msn.com'],
105        'BingPreview' => ['.search.msn.com'],
106        'Google'      => ['.google.com', '.googlebot.com'],
107        'MojeekBot'   => ['.mojeek.com'],
108        'Mail.RU_Bot' => ['.mail.ru'],
109        'msnbot'      => ['.search.msn.com'],
110        'Qwantify'    => ['.search.qwant.com'],
111        'Sogou'       => ['.crawl.sogou.com'],
112        'Yahoo'       => ['.crawl.yahoo.net'],
113        'Yandex'      => ['.yandex.ru', '.yandex.net', '.yandex.com'],
114    ];
115
116    /**
117     * Some search engines only use reverse DNS to verify the IP address.
118     *
119     * @see https://help.baidu.com/question?prod_id=99&class=0&id=3001
120     * @see https://napoveda.seznam.cz/en/full-text-search/seznambot-crawler
121     * @see https://www.ionos.de/terms-gtc/faq-crawler
122     */
123    private const ROBOT_REV_ONLY_DNS = [
124        'Baiduspider' => ['.baidu.com', '.baidu.jp'],
125        'FreshBot'    => ['.seznam.cz'],
126        'IonCrawl'    => ['.1und1.org'],
127        'Neevabot'    => ['.neeva.com'],
128    ];
129
130    /**
131     * Some search engines operate from designated IP addresses.
132     *
133     * @see https://www.apple.com/go/applebot
134     * @see https://help.duckduckgo.com/duckduckgo-help-pages/results/duckduckbot
135     */
136    private const ROBOT_IPS = [
137        'AppleBot'    => [
138            '17.0.0.0/8',
139        ],
140        'Ask Jeeves'  => [
141            '65.214.45.143',
142            '65.214.45.148',
143            '66.235.124.192',
144            '66.235.124.7',
145            '66.235.124.101',
146            '66.235.124.193',
147            '66.235.124.73',
148            '66.235.124.196',
149            '66.235.124.74',
150            '63.123.238.8',
151            '202.143.148.61',
152        ],
153        'DuckDuckBot' => [
154            '23.21.227.69',
155            '50.16.241.113',
156            '50.16.241.114',
157            '50.16.241.117',
158            '50.16.247.234',
159            '52.204.97.54',
160            '52.5.190.19',
161            '54.197.234.188',
162            '54.208.100.253',
163            '54.208.102.37',
164            '107.21.1.8',
165        ],
166    ];
167
168    /**
169     * Some search engines operate from designated IP addresses.
170     *
171     * @see https://bot.seekport.com/
172     */
173    private const ROBOT_IP_FILES = [
174        'SeekportBot' => 'https://bot.seekport.com/seekportbot_ips.txt',
175    ];
176
177    /**
178     * Some search engines operate from within a designated autonomous system.
179     *
180     * @see https://developers.facebook.com/docs/sharing/webmasters/crawler
181     * @see https://www.facebook.com/peering/
182     */
183    private const ROBOT_ASNS = [
184        'facebook' => ['AS32934', 'AS63293'],
185        'twitter'  => ['AS13414'],
186    ];
187
188    /**
189     * @param ServerRequestInterface  $request
190     * @param RequestHandlerInterface $handler
191     *
192     * @return ResponseInterface
193     */
194    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
195    {
196        $ua      = Validator::serverParams($request)->string('HTTP_USER_AGENT', '');
197        $ip      = Validator::attributes($request)->string('client-ip');
198        $address = IPFactory::parseAddressString($ip);
199        assert($address instanceof AddressInterface);
200
201        foreach (self::BAD_ROBOTS as $robot) {
202            if (str_contains($ua, $robot)) {
203                return $this->response();
204            }
205        }
206
207        foreach (self::ROBOT_REV_FWD_DNS as $robot => $valid_domains) {
208            if (str_contains($ua, $robot) && !$this->checkRobotDNS($ip, $valid_domains, false)) {
209                return $this->response();
210            }
211        }
212
213        foreach (self::ROBOT_REV_ONLY_DNS as $robot => $valid_domains) {
214            if (str_contains($ua, $robot) && !$this->checkRobotDNS($ip, $valid_domains, true)) {
215                return $this->response();
216            }
217        }
218
219        foreach (self::ROBOT_IPS as $robot => $valid_ip_ranges) {
220            if (str_contains($ua, $robot)) {
221                foreach ($valid_ip_ranges as $ip_range) {
222                    $range = IPFactory::parseRangeString($ip_range);
223
224                    if ($range instanceof RangeInterface && $range->contains($address)) {
225                        continue 2;
226                    }
227                }
228
229                return $this->response();
230            }
231        }
232
233        foreach (self::ROBOT_IP_FILES as $robot => $url) {
234            if (str_contains($ua, $robot)) {
235                $valid_ip_ranges = $this->fetchIpRangesForUrl($robot, $url);
236
237                foreach ($valid_ip_ranges as $ip_range) {
238                    $range = IPFactory::parseRangeString($ip_range);
239
240                    if ($range instanceof RangeInterface && $range->contains($address)) {
241                        continue 2;
242                    }
243                }
244
245                return $this->response();
246            }
247        }
248
249        foreach (self::ROBOT_ASNS as $robot => $asns) {
250            foreach ($asns as $asn) {
251                if (str_contains($ua, $robot)) {
252                    foreach ($this->fetchIpRangesForAsn($asn) as $range) {
253                        if ($range->contains($address)) {
254                            continue 2;
255                        }
256                    }
257
258                    return $this->response();
259                }
260            }
261        }
262
263        // Allow sites to block access from entire networks.
264        $block_asn = Validator::attributes($request)->string('block_asn', '');
265        preg_match_all('/(AS\d+)/', $block_asn, $matches);
266
267        foreach ($matches[1] as $asn) {
268            foreach ($this->fetchIpRangesForAsn($asn) as $range) {
269                if ($range->contains($address)) {
270                    return $this->response();
271                }
272            }
273        }
274
275        return $handler->handle($request);
276    }
277
278    /**
279     * Check that an IP address belongs to a robot operator using a forward/reverse DNS lookup.
280     *
281     * @param string        $ip
282     * @param array<string> $valid_domains
283     * @param bool          $reverse_only
284     *
285     * @return bool
286     */
287    private function checkRobotDNS(string $ip, array $valid_domains, bool $reverse_only): bool
288    {
289        $host = gethostbyaddr($ip);
290
291        if ($host === false) {
292            return false;
293        }
294
295        foreach ($valid_domains as $domain) {
296            if (str_ends_with($host, $domain)) {
297                return $reverse_only || $ip === gethostbyname($host);
298            }
299        }
300
301        return false;
302    }
303
304    /**
305     * Perform a whois search for an ASN.
306     *
307     * @param string $asn - The autonomous system number to query
308     *
309     * @return array<RangeInterface>
310     */
311    private function fetchIpRangesForAsn(string $asn): array
312    {
313        return Registry::cache()->file()->remember('whois-asn-' . $asn, static function () use ($asn): array {
314            $mapper = static fn (AsnRouteInfo $route_info): ?RangeInterface => IPFactory::parseRangeString($route_info->route ?: $route_info->route6);
315
316            try {
317                $loader = new CurlLoader(self::WHOIS_TIMEOUT);
318                $whois  = new Whois($loader);
319                $info   = $whois->loadAsnInfo($asn);
320                $routes = $info->routes;
321                $ranges = array_map($mapper, $routes);
322
323                return array_filter($ranges);
324            } catch (Throwable) {
325                return [];
326            }
327        }, random_int(self::WHOIS_TTL_MIN, self::WHOIS_TTL_MAX));
328    }
329
330    /**
331     * Fetch a list of IP addresses from a remote file.
332     *
333     * @param string $ua
334     * @param string $url
335     *
336     * @return array<string>
337     */
338    private function fetchIpRangesForUrl(string $ua, string $url): array
339    {
340        return Registry::cache()->file()->remember('url-ip-list-' . $ua, static function () use ($url): array {
341            try {
342                $client   = new Client();
343                $response = $client->get($url, ['timeout' => 5]);
344                $contents = $response->getBody()->getContents();
345
346                preg_match_all(self::REGEX_IPV4, $contents, $matches);
347
348                return $matches[0];
349            } catch (GuzzleException) {
350                return [];
351            }
352        }, random_int(self::WHOIS_TTL_MIN, self::WHOIS_TTL_MAX));
353    }
354
355    /**
356     * @return ResponseInterface
357     */
358    private function response(): ResponseInterface
359    {
360        return response('Not acceptable', StatusCodeInterface::STATUS_NOT_ACCEPTABLE);
361    }
362}
363