get-ip-address-optimized.php

<?php

function get_ip_address() {

    $ip_keys = array('HTTP_CLIENT_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'REMOTE_ADDR');

    foreach ($ip_keys as $key) {
        
        if (array_key_exists($key, $_SERVER) === true) {
            $items = explode(',', $_SERVER[$key]);
            $value = (is_array($items)) ? end($items) : $items;
            $ip = filter_var(trim($value), FILTER_VALIDATE_IP, FILTER_FLAG_IPV4 | FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE);
        }
	        
    }
	    
    return ($ip) ? $ip : '';

}

get-ip-address.php

<?php
/**
 * Retrieves the best guess of the client's actual IP address.
 * Takes into account numerous HTTP proxy headers due to variations
 * in how different ISPs handle IP addresses in headers between hops.
 */
function get_ip_address() {
 
    $ip_keys = array('HTTP_CLIENT_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'REMOTE_ADDR');
 
    foreach ($ip_keys as $key) {
        
        if (array_key_exists($key, $_SERVER) === true) {
            $value = (is_array($items)) ? end($items) : $items;
            $ip = filter_var(trim($value), FILTER_VALIDATE_IP, FILTER_FLAG_IPV4 | FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE);
        }
	        
    }
	    
    return ($ip) ? $ip : '';
 
}