getenv("HTTP_XXX) return nothing

Why this code return "" :

$ip = "";
if(getenv("HTTP_CLIENT_IP")) 
{
 $ip = getenv("HTTP_CLIENT_IP");
} elseif(getenv("HTTP_X_FORWARDED_FOR")) {
 $ip = getenv("HTTP_X_FORWARDED_FOR");
} else {
 $ip = getenv("REMOTE_ADDR");
}

Environment: W2003EE, IIS 6.0, PHP 5.2.9 (ISAPI)

$_SERVER is a built-in PHP variable. ge开发者_Go百科tenv() looks at the current environment.

In my case i need to use $_SERVER. Thank all!

Try $_SERVER['REMOTE_ADDR'] or $_SERVER['HTTP_X_FORWARDED_FOR']

If you wonder what is set you can dump $_SERVER somewhere.

The value of environment variable REMOTE_ADDR must be empty or not set. If working on linux check its value on terminal by the command echo $REMOTE_ADDR. If it returns null, sets its value before assigning $ip.

The problem may have something to do with IIS working a bit differently. I've had success with these two function from the CakePHP project.

/**
 * Gets remote client IP
 *
 * @return string Client IP address
 * @access public
 */
function getClientIP($safe = true) {
    if (!$safe && env('HTTP_X_FORWARDED_FOR') != null) {
        $ipaddr = preg_replace('/(?:,.*)/', '', env('HTTP_X_FORWARDED_FOR'));
    } else {
        if (env('HTTP_CLIENT_IP') != null) {
            $ipaddr = env('HTTP_CLIENT_IP');
        } else {
            $ipaddr = env('REMOTE_ADDR');
        }
    }

    if (env('HTTP_CLIENTADDRESS') != null) {
        $tmpipaddr = env('HTTP_CLIENTADDRESS');

        if (!empty($tmpipaddr)) {
            $ipaddr = preg_replace('/(?:,.*)/', '', $tmpipaddr);
        }
    }
    return trim($ipaddr);
}

/**
 * Gets an environment variable from available sources, and provides emulation
 * for unsupported or inconsistent environment variables (i.e. DOCUMENT_ROOT on
 * IIS, or SCRIPT_NAME in CGI mode).  Also exposes some additional custom
 * environment information.
 *
 * @param  string $key Environment variable name.
 * @return string Environment variable setting.
 * @link http://book.cakephp.org/view/701/env
 */
    function env($key) {
        if ($key == 'HTTPS') {
            if (isset($_SERVER['HTTPS'])) {
                return (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off');
            }
            return (strpos(env('SCRIPT_URI'), 'https://') === 0);
        }

        if ($key == 'SCRIPT_NAME') {
            if (env('CGI_MODE') && isset($_ENV['SCRIPT_URL'])) {
                $key = 'SCRIPT_URL';
            }
        }

        $val = null;
        if (isset($_SERVER[$key])) {
            $val = $_SERVER[$key];
        } elseif (isset($_ENV[$key])) {
            $val = $_ENV[$key];
        } elseif (getenv($key) !== false) {
            $val = getenv($key);
        }

        if ($key === 'REMOTE_ADDR' && $val === env('SERVER_ADDR')) {
            $addr = env('HTTP_PC_REMOTE_ADDR');
            if ($addr !== null) {
                $val = $addr;
            }
        }

        if ($val !== null) {
            return $val;
        }

        switch ($key) {
            case 'SCRIPT_FILENAME':
                if (defined('SERVER_IIS') && SERVER_IIS === true) {
                    return str_replace('\\\\', '\\', env('PATH_TRANSLATED'));
                }
            break;
            case 'DOCUMENT_ROOT':
                $name = env('SCRIPT_NAME');
                $filename = env('SCRIPT_FILENAME');
                $offset = 0;
                if (!strpos($name, '.php')) {
                    $offset = 4;
                }
                return substr($filename, 0, strlen($filename) - (strlen($name) + $offset));
            break;
            case 'PHP_SELF':
                return str_replace(env('DOCUMENT_ROOT'), '', env('SCRIPT_FILENAME'));
            break;
            case 'CGI_MODE':
                return (PHP_SAPI === 'cgi');
            break;
            case 'HTTP_BASE':
                $host = env('HTTP_HOST');
                if (substr_count($host, '.') !== 1) {
                    return preg_replace('/^([^.])*/i', null, env('HTTP_HOST'));
                }
            return '.' . $host;
            break;
        }
        return null;
    }