Codeigniter 3.011 base_url detection

config.php

<?php
# Source: https://codeigniter.com/userguide3/installation/upgrade_303.html

$config['base_url'] = ['domain1.tld', 'domain2.tld'];

if (in_array($_SERVER['HTTP_HOST'], $config['base_url'], true)) {
    $domain = $_SERVER['HTTP_HOST'];
} else {
    $domain = $config['base_url'][0];
}
if (! empty($_SERVER['HTTPS'])) {
    $config['base_url'] = 'https://'.$domain;
} else {
    $config['base_url'] = 'http://'.$domain;
}