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Googlebot からのアクセスかどうかを厳密にチェックする
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| <?php | |
| /** | |
| * Googlebot からのアクセスかどうかを厳密にチェックするクラス。 | |
| * 使い方: GoogleBotStrictVerifier::isGoogleBot() | |
| */ | |
| class GoogleBotStrictVerifier | |
| { | |
| /** | |
| * User-Agent および IP の逆引きから Googlebot かどうかを判定する。 | |
| * @return boolean | |
| */ | |
| public static function isGoogleBot() | |
| { | |
| if (!self::isGoogleBotUserAgent()) { | |
| return false; | |
| } | |
| return self::isGoogleIpAddr(); | |
| } | |
| /** | |
| * Googlebot の IP アドレスかどうかを DNS 逆引きで判定する。 | |
| * @return boolean | |
| */ | |
| private static function isGoogleIpAddr() | |
| { | |
| $ip = self::getRemoteIpAddr(); | |
| if(!filter_var($ip, FILTER_VALIDATE_IP)) { | |
| return false; | |
| } | |
| $hostname = gethostbyaddr($ip); | |
| if (!preg_match('/(?:\.googlebot|google)\.com$/i', $hostname)) { | |
| return false; | |
| } | |
| $hosts = gethostbynamel($hostname); | |
| return is_array($hosts) && in_array($ip, $hosts, true); | |
| } | |
| /** | |
| * User-Agent が Googlebot かどうかを判定する。 | |
| * @return boolean | |
| */ | |
| private static function isGoogleBotUserAgent() | |
| { | |
| if (!isset($_SERVER['HTTP_USER_AGENT'])) { | |
| return false; | |
| } | |
| return preg_match('/googlebot/i', $_SERVER['HTTP_USER_AGENT']); | |
| } | |
| /** | |
| * クライアント IP アドレスを取得する。 | |
| * @return string | |
| */ | |
| private static function getRemoteIpAddr() | |
| { | |
| if (isset($_SERVER['HTTP_CLIENT_IP']) && !empty($_SERVER['HTTP_CLIENT_IP'])) { | |
| return $_SERVER['HTTP_CLIENT_IP']; | |
| } | |
| if (isset($_SERVER['HTTP_X_FORWARDED_FOR']) && !empty($_SERVER['HTTP_X_FORWARDED_FOR'])) { | |
| $ips = explode(', ', $_SERVER['HTTP_X_FORWARDED_FOR']); | |
| return reset($ips); | |
| } | |
| if (isset($_SERVER['REMOTE_ADDR']) && !empty($_SERVER['REMOTE_ADDR'])) { | |
| return $_SERVER['REMOTE_ADDR']; | |
| } | |
| return '127.0.0.1'; | |
| } | |
| } |
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