A PHP script to check and display SSL certificate expiration in Google and .ical calendars

certificate_checker.php

<?php

$urls[] = array(
        "name" => "Domain 1 Name",
        "url" => "https://domain.com"
);

$urls[] = array(
        "name" => "Domain 2 Name",
        "url" => "https://subdomain.domain.org"
);

$urls[] = array(
        "name" => "Domain 3 Name",
        "url" => "https://domain.io"
);






echo 'BEGIN:VCALENDAR' . "\n";
echo 'VERSION:2.0' . "\n";
echo 'PRODID:-//hacksw/handcal//NONSGML v1.0//EN' . "\n\n";

foreach($urls as $value) {
   
    $orignal_parse = parse_url($value['url'], PHP_URL_HOST);
    $get = stream_context_create(array("ssl" => array("capture_peer_cert" => TRUE)));
    $read = stream_socket_client("ssl://".$orignal_parse.":443", $errno, $errstr, 30, STREAM_CLIENT_CONNECT, $get);
    $cert = stream_context_get_params($read);
    $certinfo = openssl_x509_parse($cert['options']['ssl']['peer_certificate']);
    $valid_to_unix = $certinfo['validTo_time_t'];
    
    echo "BEGIN:VEVENT\n";
    echo "UID:" . uniqid() . "\n";
    echo "DTSTAMP:".date("Ymd")."T".date("His")."Z\n";
    echo "DTSTART:".date("Ymd", $valid_to_unix)."T080000Z\n";
    echo "DTEND:".date("Ymd", $valid_to_unix)."T160000Z\n";
    echo "SUMMARY:SSL Cert - {$value['name']}\n";
    echo "END:VEVENT\n\n";
    
}

echo "END:VCALENDAR";

Thank you for posting this code! It's much easier than calling openssl from the command line.

You're very welcome! Thank you for leaving a comment! I've got about 10 domains on it and it's been so useful.