isdowndetectordown/core/check.php

<?php
// core/check.php
declare(strict_types=1);

require __DIR__ . '/connection.php';

date_default_timezone_set('Asia/Kolkata');

// fetch regions from DB
$regions = db()->query("
    SELECT region, url
    FROM regions
    ORDER BY id ASC
")->fetchAll();

function runCheck(string $url): array
{
    $ch = curl_init($url);

    curl_setopt_array($ch, [
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_FOLLOWLOCATION => true,
        CURLOPT_TIMEOUT        => 10,
        CURLOPT_CONNECTTIMEOUT => 5,
        CURLOPT_NOBODY         => false,
        CURLOPT_ENCODING       => '',
        CURLOPT_USERAGENT      =>
            'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) ' .
            'AppleWebKit/605.1.15 (KHTML, like Gecko) ' .
            'Version/17.0 Safari/605.1.15',
    ]);

    $start  = microtime(true);
    curl_exec($ch);
    $status = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    $error  = curl_error($ch);
    $end    = microtime(true);

    curl_close($ch);

    $rt = (int) round(($end - $start) * 1000);

    // default values
    $up   = 0;
    $note = null;
    $lat  = $rt;

    if ($error) {
        // cannot reach the domain at all
        $up   = 0;
        $lat  = null;
        $note = 'cannot_fetch_web';
    } else {
        // 200–499 = server is UP
        if ($status >= 200 && $status < 500) {
            $up = 1;

            if ($status === 403) {
                $note = 'blocked_by_protection';
            } elseif ($status === 429) {
                $note = 'too_many_requests';
            }
        }
        // 500–599 = Cloudflare-style origin error / server-side error
        elseif ($status >= 500 && $status <= 599) {
            $up   = 0;
            $note = 'cloudflare_origin_error';
        }
    }

    return [
        'status'  => $status,
        'up'      => $up,
        'latency' => $lat,
        'error'   => $note
    ];
}

$stmt = db()->prepare("
    INSERT INTO checks (
        region,
        monitor_url,
        checked_at,
        status_code,
        is_up,
        response_time_ms,
        error_message
    ) VALUES (
        :region,
        :url,
        NOW(),
        :status,
        :up,
        :lat,
        :err
    )
");

$output = [];

foreach ($regions as $r) {
    $check = runCheck($r['url']);

    $stmt->execute([
        ':region' => $r['region'],
        ':url'    => $r['url'],
        ':status' => $check['status'],
        ':up'     => $check['up'],
        ':lat'    => $check['latency'],
        ':err'    => $check['error']
    ]);

    $output[] = [
        'region' => $r['region'],
        'url'    => $r['url'],
        'check'  => $check
    ];
}

header("Content-Type: application/json; charset=utf-8");
echo json_encode($output, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE);