获取公共IP地址

Question

所以我试图创建一个应用程序，告诉你你的公共IP地址，我已经让它工作，但是当离线它只是打破程序，我想让它在文本框中说“没有连接”而不是刚破坏......这就是我到目前为止所做的。

private string getMyIPAddress()
{
    string Address = "";
    WebRequest request = WebRequest.Create("http://checkip.dyndns.com");
    using (WebResponse response = request.GetResponse())
    using (StreamReader stream = new StreamReader(response.GetResponseStream()))
    {
        Address = stream.ReadToEnd();
    }
    int first = Address.IndexOf("Address: ") + 9;
    int last = Address.IndexOf("</body>");
    Address = Address.Substring(first, last - first);
    textBox4.Text = Address;

    return Address;
}