[root@ip-xxx-xxx-xxx-xxx public]# vim index.php    

if ($trustedProxies = $_SERVER['TRUSTED_PROXIES'] ?? false) {
    Request::HEADER_X_FORWARDED_AWS_ELB;
}

if ($trustedHosts = $_SERVER['TRUSTED_HOSTS'] ?? false) {
    Request::setTrustedHosts(array('^(.+\.)?XXXX\.XXX$'));
}

[root@ip-xxx-xxx-xxx-xxx public]# php index.php

Notice: Uninitialized string offset: 0 in /var/app/current/vendor/symfony/http-foundation/Request.php on line 1988

Notice: Uninitialized string offset: 0 in /var/app/current/vendor/symfony/http-foundation/Request.php on line 1988

Warning: ini_set(): Headers already sent. You cannot change the session module's ini settings at this time in /var/app/current/vendor/symfony/http-foundation/Session/Storage/Handler/NativeFileSessionHandler.php on line 52

Warning: ini_set(): Headers already sent. You cannot change the session module's ini settings at this time in /var/app/current/vendor/symfony/http-foundation/Session/Storage/Handler/NativeFileSessionHandler.php on line 53



private function normalizeAndFilterClientIps(array $clientIps, $ip)
{
    if (!$clientIps) {
        return array();
    }
    $clientIps[] = $ip; // Complete the IP chain with the IP the request actually came from
    $firstTrustedIp = null;

    foreach ($clientIps as $key => $clientIp) {
        if (strpos($clientIp, '.')) {
            // Strip :port from IPv4 addresses. This is allowed in Forwarded
            // and may occur in X-Forwarded-For.
            $i = strpos($clientIp, ':');
            if ($i) {
                $clientIps[$key] = $clientIp = substr($clientIp, 0, $i);
            }
        // line 1988 ---->
        } elseif ('[' == $clientIp[0]) {
            // Strip brackets and :port from IPv6 addresses.
            $i = strpos($clientIp, ']', 1);
            $clientIps[$key] = $clientIp = substr($clientIp, 1, $i - 1);
        }

        if (!filter_var($clientIp, FILTER_VALIDATE_IP)) {
            unset($clientIps[$key]);

            continue;
        }

        if (IpUtils::checkIp($clientIp, self::$trustedProxies)) {
            unset($clientIps[$key]);

            // Fallback to this when the client IP falls into the range of trusted proxies
            if (null === $firstTrustedIp) {
                $firstTrustedIp = $clientIp;
            }
        }
    }

    // Now the IP chain contains only untrusted proxies and the client IP
    return $clientIps ? array_reverse($clientIps) : array($firstTrustedIp);
}