using System;
using System.Threading.Tasks;
using System.Net;

namespace DnsLookup
{
    class Program
    {
        /// <summary>
        /// 樣例應(yīng)用程序?qū)崿F(xiàn)一個(gè)控制臺(tái)程序（包），要求用戶輸入主機(jī)名（也可以添加一個(gè)IP地址），
        /// 通過Dns.GetHostEntryAsync得到一個(gè)IPHostEntry。在IPHostEntry中，使用AddressList屬性訪問地址列表。
        /// 主機(jī)的所有地址以及AddressFamily都寫入控制臺(tái)。
        /// 
        /// </summary>
        /// <param name="args"></param>
        /// <returns></returns>
        static async Task Main(string[] args)
        {
            do
            {
                Console.Write("Hostname:\t");
                string hostname = Console.ReadLine();
                if (hostname.CompareTo("exit") == 0)
                {
                    Console.WriteLine("bye!");
                    return;
                }
                await OnLookupAsync(hostname);
                Console.WriteLine();
            } while (true);
        }

        public static async Task OnLookupAsync(string hostname)
        {
            try
            {
                IPHostEntry ipHost = await Dns.GetHostEntryAsync(hostname);
                Console.WriteLine($"Hostname: {ipHost.HostName}");
                foreach (IPAddress address in ipHost.AddressList)
                {
                    Console.WriteLine($"Address Family: {address.AddressFamily}");
                    Console.WriteLine($"Address: {address}");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }
    }
}