使用 PHP 获取网站 SSL 证书信息

前两天，有用户反馈网站突然打不开了，看了一下用户给的截图，应该是网站的证书过期了。 赶紧爬起来更新了一下证书。为了避免再次发生这种尴尬的事情，想着写一个简单的脚本， 监控网站的证书到期时间，以便提醒自己及时更新证书。

因为自己平时还是和 php 打交道比较多，也有现成的短信、邮件、企业微信等通知方式可用， 所以还是决定用 php 来实现。 关于如何使用PHP获取网站的SSL证书，经过简单的搜索和尝试，还是比较简单的，直接附上代码：

$url = 'https://www.httpbin.org/';
$host = parse_url($url, PHP_URL_HOST);
$streamContext = stream_context_create(['ssl' => ['capture_peer_cert' => true]]);
$socket = stream_socket_client(
    'ssl://'.$host.':443',
    $errorNo,
    $errorMessage,
    30,
    STREAM_CLIENT_CONNECT,
    $streamContext
);
if ($socket === false) {
    echo "[ERROR] Failed to open socket connection: {$errorNo} - {$errorMessage}".PHP_EOL;
    exit(1);
}
$parameters = stream_context_get_params($socket);
$certificate = openssl_x509_parse($parameters['options']['ssl']['peer_certificate']);
print_r($certificate);

解析后的证书信息如下：

[
    'name' => '/CN=httpbin.org',
    'subject' => [
        'CN' => 'httpbin.org',
    ],
    'hash' => '5a356b71',
    'issuer' => [
        'C' => 'US',
        'O' => 'Amazon',
        'OU' => 'Server CA 1B',
        'CN' => 'Amazon',
    ],
    'version' => 2,
    'serialNumber' => '15511154429359216763915851913648262204',
    'serialNumberHex' => '0BAB56F52FC9F721C8C35BFC58E9CC3C',
    'validFrom' => '200118000000Z',
    'validTo' => '210218120000Z',
    'validFrom_time_t' => 1579305600,
    'validTo_time_t' => 1613649600,
    'signatureTypeSN' => 'RSA-SHA256',
    'signatureTypeLN' => 'sha256WithRSAEncryption',
    'signatureTypeNID' => 668,
    'purposes' => [
        1 => [
            true,
            false,
            'sslclient',
        ],
        2 => [
            true,
            false,
            'sslserver',
        ],
        3 => [
            true,
            false,
            'nssslserver',
        ],
        4 => [
            false,
            false,
            'smimesign',
        ],
        5 => [
            false,
            false,
            'smimeencrypt',
        ],
        6 => [
            false,
            false,
            'crlsign',
        ],
        7 => [
            true,
            true,
            'any',
        ],
        8 => [
            true,
            false,
            'ocsphelper',
        ],
        9 => [
            false,
            false,
            'timestampsign',
        ],
    ],
    'extensions' => [
        'authorityKeyIdentifier' => "keyid:59:A4:66:06:52:A0:7B:95:92:3C:A3:94:07:27:96:74:5B:F9:3D:D0\n",
        'subjectKeyIdentifier' => '4D:47:D7:1B:DA:3A:E5:FB:D0:31:40:CA:CE:35:D6:54:B9:C8:EF:A5',
        'subjectAltName' => 'DNS:httpbin.org, DNS:*.httpbin.org',
        'keyUsage' => 'Digital Signature, Key Encipherment',
        'extendedKeyUsage' => 'TLS Web Server Authentication, TLS Web Client Authentication',
        'crlDistributionPoints' => "
         \n
         Full Name:\n
           URI:http://crl.sca1b.amazontrust.com/sca1b.crl\n
         ",
        'certificatePolicies' => "
         Policy: 2.16.840.1.114412.1.2\n
         Policy: 2.23.140.1.2.1\n
         ",
        'authorityInfoAccess' => "
         OCSP - URI:http://ocsp.sca1b.amazontrust.com\n
         CA Issuers - URI:http://crt.sca1b.amazontrust.com/sca1b.crt\n
         ",
        'basicConstraints' => 'CA:FALSE',
        'ct_precert_scts' => "
         Signed Certificate Timestamp:\n
             Version   : v1 (0x0)\n
             Log ID    : EE:4B:BD:B7:75:CE:60:BA:E1:42:69:1F:AB:E1:9E:66:\n
                         A3:0F:7E:5F:B0:72:D8:83:00:C4:7B:89:7A:A8:FD:CB\n
             Timestamp : Jan 18 01:26:21.019 2020 GMT\n
             Extensions: none\n
             Signature : ecdsa-with-SHA256\n
                         30:45:02:21:00:81:00:82:78:B4:00:81:AD:D1:F0:07:\n
                         86:67:18:81:93:CB:7F:FD:17:1B:99:F4:62:28:1E:07:\n
                         D7:E5:18:DE:7D:02:20:79:76:3E:C7:BA:16:42:62:12:\n
                         85:70:AB:05:27:6A:79:36:17:AE:CC:50:71:61:3A:66:\n
                         90:32:43:17:2C:75:45\n
         Signed Certificate Timestamp:\n
             Version   : v1 (0x0)\n
             Log ID    : 87:75:BF:E7:59:7C:F8:8C:43:99:5F:BD:F3:6E:FF:56:\n
                         8D:47:56:36:FF:4A:B5:60:C1:B4:EA:FF:5E:A0:83:0F\n
             Timestamp : Jan 18 01:26:21.098 2020 GMT\n
             Extensions: none\n
             Signature : ecdsa-with-SHA256\n
                         30:45:02:20:10:CC:62:29:B6:B0:5F:1E:1E:95:B5:67:\n
                         BF:F2:43:59:62:4F:06:BC:21:14:A3:89:D0:5D:F5:95:\n
                         48:C1:EE:A6:02:21:00:EC:33:CE:4D:A4:60:73:F7:07:\n
                         DC:EC:C8:19:2B:BA:74:B6:9E:7B:91:7F:61:19:26:0B:\n
                         D4:E2:91:68:96:4C:2F
         ",
    ],
]

可以看到证书信息中的 validTo_time_t 就是证书到期时间。简单的配合 CRONTAB 每天检查一遍，就可以提前通知自己“证书即将到期，请及时更新”。