在C#中解析DNS中的IP地址

Question

我正在尝试与IP地址建立TCP套接字连接.我可以通过直接解析这样的IP地址来做到这一点:

IPAddress ipAddress = IPAddress.Parse("192.168.1.123");
IPEndPoint remoteEP = new IPEndPoint(ipAddress, 80);
// Create a TCP/IP  socket.
Socket sender = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);  // This works!

但是,我无法弄清楚如何从DNS字符串中划分这个IP地址.我尝试了以下各种组合:

IPAddress ipAddress = Dns.Resolve("www.mydns.org");   // No dice
IPAddress ipAddress = Dns.GetHostEntry("www.mydns.org");  // Nada
IPAddress ipAddress = IPAddress.Parse(Dns.Resolve("www.mydns.org"));   // So many errors...
IPAddress ipAddress = IPAddress.Parse(Dns.Resolve("www.mydns.org").toString());  // WTh is this attempt anyway?

你们这些善良的灵魂有没有提示帮助我从DNS中挤出IPAddress？

Answer 1

foreach (IPAddress ip in Dns.GetHostAddresses("www.mydns.org"))
{
    Console.WriteLine(ip.ToString());
}

或者只是IPAddress address = Dns.GetHostAddresses("www.mydns.org")[0];如果你只想要第一个.

Answer 2

我有一个非常简洁的扩展方法就是这样!

我考虑到IPV6可能会作为DNS类返回的地址列表中的第一个地址返回,并允许您在结果上"支持"IPV6或IPV4.以下是完整记录的类(出于简洁的原因,仅针对此案例的相关方法):

using System;
using System.Linq;
using System.Net;
using System.Net.Sockets;

/// <summary>
/// Basic helper methods around networking objects (IPAddress, IpEndPoint, Socket, etc.)
/// </summary>
public static class NetworkingExtensions
{
    /// <summary>
    /// Converts a string representing a host name or address to its <see cref="IPAddress"/> representation, 
    /// optionally opting to return a IpV6 address (defaults to IpV4)
    /// </summary>
    /// <param name="hostNameOrAddress">Host name or address to convert into an <see cref="IPAddress"/></param>
    /// <param name="favorIpV6">When <code>true</code> will return an IpV6 address whenever available, otherwise 
    /// returns an IpV4 address instead.</param>
    /// <returns>The <see cref="IPAddress"/> represented by <paramref name="hostNameOrAddress"/> in either IpV4 or
    /// IpV6 (when available) format depending on <paramref name="favorIpV6"/></returns>
    public static IPAddress ToIPAddress(this string hostNameOrAddress, bool favorIpV6=false)
    {
        var favoredFamily = favorIpV6 ? AddressFamily.InterNetworkV6 : AddressFamily.InterNetwork;
        var addrs = Dns.GetHostAddresses(hostNameOrAddress);
        return addrs.FirstOrDefault(addr => addr.AddressFamily == favoredFamily)
               ??
               addrs.FirstOrDefault();
    }
}

不要忘记将此类放在命名空间中!:-)

现在你可以简单地这样做:

var server = "http://simpax.com.br".ToIPAddress();
var blog = "http://simpax.codax.com.br".ToIPAddress();
var google = "google.com.br".ToIPAddress();
var ipv6Google = "google.com.br".ToIPAddress(true); // if available will be an IPV6