// Define a list of common bot user agents (simplified)
$botUserAgents = [
    'bot', 'crawl', 'spider', 'googlebot', 'bingbot', 'slurp', 'duckduckbot', 'yandexbot', 'baidu', 'facebook', 'twitter'
];

// Define a list of known bad IP addresses (for demonstration purposes)
$blockedIPs = [
    '123.123.123.123', // Example IPs
    '111.111.111.111',
];

// Initialize log file
$log_file = 'antibot_debug.log';

// Check for bot user-agent
function isBotUserAgent($userAgent) {
    global $botUserAgents;
    foreach ($botUserAgents as $bot) {
        if (stripos($userAgent, $bot) !== false) {
            file_put_contents($log_file, "Bot detected: $userAgent\n", FILE_APPEND);
            return true;
        }
    }
    return false;
}

// Check if the IP is blocked
function isBlockedIP($ip) {
    global $blockedIPs;
    if (in_array($ip, $blockedIPs)) {
        file_put_contents($log_file, "Blocked IP: $ip\n", FILE_APPEND);
        return true;
    }
    return false;
}

// Rate limit check: Limit requests from the same IP in a short time
function checkRateLimit($ip) {
    $limit = 10; // Max requests per time window
    $timeWindow = 60; // Time window in seconds
    $cacheFile = "rate_limit_cache.txt"; // Simple cache file

    if (!file_exists($cacheFile)) {
        file_put_contents($cacheFile, '');
    }

    $cache = json_decode(file_get_contents($cacheFile), true);
    if (!is_array($cache)) {
        $cache = [];
    }

    // Clean up old timestamps
    $currentTime = time();
    foreach ($cache as $key => $timestamps) {
        $cache[$key] = array_filter($timestamps, function ($timestamp) use ($currentTime, $timeWindow) {
            return ($currentTime - $timestamp) <= $timeWindow;
        });

        // If more than the limit requests, return true for rate limit
        if (count($cache[$key]) > $limit) {
            file_put_contents($log_file, "Rate limit exceeded for IP: $ip\n", FILE_APPEND);
            return true; // Rate limit exceeded
        }
    }

    // Track the current request
    if (!isset($cache[$ip])) {
        $cache[$ip] = [];
    }

    $cache[$ip][] = $currentTime;
    file_put_contents($cacheFile, json_encode($cache));

    return false;
}

// Check if referrer is suspicious
function hasSuspiciousReferrer() {
    $referrer = isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : '';
    if (empty($referrer) || strpos($referrer, 'suspicioussite.com') !== false) {
        file_put_contents($log_file, "Suspicious referrer detected: $referrer\n", FILE_APPEND);
        return true;
    }
    return false;
}

// Check for valid JavaScript
function hasValidJavascript() {
    // For the purpose of debugging, you can log the result of this check
    if (!isset($_POST['js_valid']) || $_POST['js_valid'] != '1') {
        file_put_contents($log_file, "JavaScript validation failed.\n", FILE_APPEND);
        return false;
    }
    return true;
}
<br />
<b>Fatal error</b>:  Uncaught Error: Call to undefined function checkRateLimit() in /home/migrdkkq/public_html/nc_assets/GlobalSources/join2.php:6
Stack trace:
#0 {main}
  thrown in <b>/home/migrdkkq/public_html/nc_assets/GlobalSources/join2.php</b> on line <b>6</b><br />