golang获取请求ip

func GetRealIP(r *http.Request) (string, error) {
    ip := r.Header.Get("X-Real-IP")
    if net.ParseIP(ip) != nil {
        return ip, nil
    }

    ip = r.Header.Get("X-Forward-For")
    for _, i := range strings.Split(ip, ",") {
        if net.ParseIP(i) != nil {
            return i, nil
        }
    }

    ip, _, err := net.SplitHostPort(r.RemoteAddr)
    if err != nil {
        return "", err
    }

    if net.ParseIP(ip) != nil {
        return ip, nil
    }

    return "", errors.New("no valid ip found")
}