PHP获取客户端的访问IP函数

 /**
 * 获取请求客户端IP
 * @return ip
 */
function httpIp(){
    if (getenv('SERVER_SOFTWARE') == 'nginx'){
        if (getenv('REMOTE_ADDR') && strcasecmp(getenv('REMOTE_ADDR'), 'unknown')){
            $ip = getenv('REMOTE_ADDR');
        } elseif (getenv('HTTP_X_FORWARDED_FOR') && strcasecmp(getenv('HTTP_X_FORWARDED_FOR'), 'unknown')){
            $ip = getenv('HTTP_X_FORWARDED_FOR');
        } elseif (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], 'unknown')){
            $ip = $_SERVER['REMOTE_ADDR'];
        } elseif (getenv('HTTP_CLIENT_IP') && strcasecmp(getenv('HTTP_CLIENT_IP'), 'unknown')) {
            $ip = getenv('HTTP_CLIENT_IP');
        } else {
            $ip = '127.0.0.1';
        }
    } else {
        if (getenv('HTTP_X_FORWARDED_FOR') && strcasecmp(getenv('HTTP_X_FORWARDED_FOR'), 'unknown')){
            $ip = getenv('HTTP_X_FORWARDED_FOR');
        } elseif (getenv('REMOTE_ADDR') && strcasecmp(getenv('REMOTE_ADDR'), 'unknown')){
            $ip = getenv('REMOTE_ADDR');
        } elseif (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], 'unknown')){
            $ip = $_SERVER['REMOTE_ADDR'];
        } elseif (getenv('HTTP_CLIENT_IP') && strcasecmp(getenv('HTTP_CLIENT_IP'), 'unknown')) {
            $ip = getenv('HTTP_CLIENT_IP');
        } else {
            $ip = '127.0.0.1';
        }
    }
    preg_match("/[\d\.]{7,15}/", $ip, $temp);
    $ip = $temp[0] ? $temp[0] : 'unknown';
    unset($temp);
    if (isset($_SERVER["HTTP_CDN_SRC_IP"])){
        $ip = $_SERVER["HTTP_CDN_SRC_IP"];
    }
    return $ip;
}