Dns.GetHostAddress 和 Dns.GetHostEntry 都只返回 ipv4 地址。如何同时获得 ipv4 和 ipv6 地址？

Question

here 和 here 和 here 提出了一个类似的问题，但似乎没有一个答案有效，所以我发布了实际代码并显示它在支持 ipv6 的机器上运行，希望有人能提出解决方案

这是两个问题的代码

using System;

public class HelloWorld
{
    static public void Main ()
    {
        string hostName = "google.com"; // uri.DnsSafeHost;
        Console.WriteLine("DNS.GetHostAddresses: " + hostName);
        var hostAddresses = System.Net.Dns.GetHostAddresses(hostName);
        Console.WriteLine("DNS.NumAddreses:" + hostAddresses.Length);
        foreach (System.Net.IPAddress hostAddress in hostAddresses)
        {
            Console.WriteLine(
                "addr: " + hostAddress.ToString() + 
                " family: " + hostAddress.AddressFamily.ToString());
        }


        System.Net.IPHostEntry ipHostEntry = System.Net.Dns.GetHostEntry(hostName);
        Console.WriteLine("DNS.GetHostEntry NumAddresses:" + ipHostEntry.AddressList.Length);
        foreach (System.Net.IPAddress hostAddress in ipHostEntry.AddressList)
        {
            Console.WriteLine(
                "addr: " + hostAddress.ToString() + 
                " family: " + hostAddress.AddressFamily.ToString());
        }
    }
}

我在带有 ipv6 的 Ubuntu 14.04 上运行它。以下是一些可能相关的信息

# ip -6 addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 2400:6180:0:d0::691:9001/64 scope global 
       valid_lft forever preferred_lft forever
    inet6 fe80::601:eeff:fe7e:201/64 scope link 
       valid_lft forever preferred_lft forever

证明 Google.com 有一个 ipv6 地址

# dig google.com AAAA +short
2404:6800:4003:c00::8a

显示我可以直接在其 ipv6 地址上 ping google.com

# ping6 2404:6800:4003:c00::8a
PING 2404:6800:4003:c00::8a(2404:6800:4003:c00::8a) 56 data bytes
64 bytes from 2404:6800:4003:c00::8a: icmp_seq=1 ttl=58 time=2.25 ms
64 bytes from 2404:6800:4003:c00::8a: icmp_seq=2 ttl=58 time=2.12 ms
^C

显示我的单声道版本

# mono --version
Mono JIT compiler version 4.2.3 (Stable 4.2.3.4/832de4b Wed Mar 16 13:19:08 UTC 2016)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
    TLS:           __thread
    SIGSEGV:       altstack
    Notifications: epoll
    Architecture:  amd64
    Disabled:      none
    Misc:          softdebug 
    LLVM:          supported, not enabled.
    GC:            sgen
# mcs --version
Mono C# compiler version 4.2.3.0

编译运行上面的例子

# mcs dns.cs
# mono dns.exe
DNS.GetHostAddresses: google.com
DNS.NumAddreses:6
addr: 74.125.200.102 family: InterNetwork
addr: 74.125.200.139 family: InterNetwork
addr: 74.125.200.138 family: InterNetwork
addr: 74.125.200.101 family: InterNetwork
addr: 74.125.200.113 family: InterNetwork
addr: 74.125.200.100 family: InterNetwork
DNS.GetHostEntry NumAddresses:6
addr: 74.125.200.100 family: InterNetwork
addr: 74.125.200.113 family: InterNetwork
addr: 74.125.200.139 family: InterNetwork
addr: 74.125.200.102 family: InterNetwork
addr: 74.125.200.138 family: InterNetwork
addr: 74.125.200.101 family: InterNetwork

一些答案​​/cmets 建议 .NET 在仅 ipv4 的机器上过滤掉 ipv6。这显然不是仅 ipv4 的机器。

注意：这里在同一台机器上的 node.js 中做同样的事情。它正确获取了 ipv6 地址以及 ipv4 地址

# node
> require('dns').lookup("google.com", {all:true}, (err, addresses) => { console.log(addresses); });
GetAddrInfoReqWrap {
  callback: { [Function: asyncCallback] immediately: true },
  family: 0,
  hostname: 'google.com',
  oncomplete: [Function: onlookupall],
  domain: 
   Domain {
     domain: null,
     _events: { error: [Function] },
     _eventsCount: 1,
     _maxListeners: undefined,
     members: [] } }
> [ { address: '74.125.200.101', family: 4 },
  { address: '74.125.200.138', family: 4 },
  { address: '74.125.200.102', family: 4 },
  { address: '74.125.200.139', family: 4 },
  { address: '74.125.200.113', family: 4 },
  { address: '74.125.200.100', family: 4 },
  { address: '2404:6800:4003:c00::65', family: 6 } ]

如何让DNS.GetHostAddresses 或DNS.GetHostEntry 同时返回 ipv6 和 ipv4 地址？

Answer 1

这取自 MSDN 网站 (https://msdn.microsoft.com/en-us/library/system.net.ipaddress(v=vs.110).aspx)，它展示了如何找到有关地址的所有相关信息，希望对您有所帮助：

// This program shows how to use the IPAddress class to obtain a server 
// IP addressess and related information.

using System;
using System.Net;
using System.Net.Sockets;
using System.Text.RegularExpressions;

namespace Mssc.Services.ConnectionManagement
{

  class TestIPAddress 
  {

    /**
      * The IPAddresses method obtains the selected server IP address information.
      * It then displays the type of address family supported by the server and its 
      * IP address in standard and byte format.
      **/
    private static void IPAddresses(string server) 
    {
      try 
      {
        System.Text.ASCIIEncoding ASCII = new System.Text.ASCIIEncoding();

        // Get server related information.
        IPHostEntry heserver = Dns.GetHostEntry(server);

        // Loop on the AddressList
        foreach (IPAddress curAdd in heserver.AddressList) 
        {


          // Display the type of address family supported by the server. If the
          // server is IPv6-enabled this value is: InternNetworkV6. If the server
          // is also IPv4-enabled there will be an additional value of InterNetwork.
          Console.WriteLine("AddressFamily: " + curAdd.AddressFamily.ToString());

          // Display the ScopeId property in case of IPV6 addresses.
          if(curAdd.AddressFamily.ToString() == ProtocolFamily.InterNetworkV6.ToString())
            Console.WriteLine("Scope Id: " + curAdd.ScopeId.ToString());


          // Display the server IP address in the standard format. In 
          // IPv4 the format will be dotted-quad notation, in IPv6 it will be
          // in in colon-hexadecimal notation.
          Console.WriteLine("Address: " + curAdd.ToString());

          // Display the server IP address in byte format.
          Console.Write("AddressBytes: ");



          Byte[] bytes = curAdd.GetAddressBytes();
          for (int i = 0; i < bytes.Length; i++) 
          {
            Console.Write(bytes[i]);
          }                          

          Console.WriteLine("\r\n");

        }

      }
      catch (Exception e) 
      {
        Console.WriteLine("[DoResolve] Exception: " + e.ToString());
      }
    }

    // This IPAddressAdditionalInfo displays additional server address information.
    private static void IPAddressAdditionalInfo() 
    {
      try 
      {
        // Display the flags that show if the server supports IPv4 or IPv6
        // address schemas.
        Console.WriteLine("\r\nSupportsIPv4: " + Socket.SupportsIPv4);
        Console.WriteLine("SupportsIPv6: " + Socket.SupportsIPv6);

        if (Socket.SupportsIPv6)
        {
          // Display the server Any address. This IP address indicates that the server 
          // should listen for client activity on all network interfaces. 
          Console.WriteLine("\r\nIPv6Any: " + IPAddress.IPv6Any.ToString());

          // Display the server loopback address. 
          Console.WriteLine("IPv6Loopback: " + IPAddress.IPv6Loopback.ToString());

          // Used during autoconfiguration first phase.
          Console.WriteLine("IPv6None: " + IPAddress.IPv6None.ToString());

          Console.WriteLine("IsLoopback(IPv6Loopback): " + IPAddress.IsLoopback(IPAddress.IPv6Loopback));
        }
        Console.WriteLine("IsLoopback(Loopback): " + IPAddress.IsLoopback(IPAddress.Loopback));
      }
      catch (Exception e) 
      {
        Console.WriteLine("[IPAddresses] Exception: " + e.ToString());
      }
    }


    public static void Main(string[] args) 
    {
      string server = null;

      // Define a regular expression to parse user's input.
      // This is a security check. It allows only
      // alphanumeric input string between 2 to 40 character long.
      Regex rex = new Regex(@"^[a-zA-Z]\w{1,39}$");

      if (args.Length < 1)
      {
        // If no server name is passed as an argument to this program, use the current 
        // server name as default.
        server = Dns.GetHostName();
        Console.WriteLine("Using current host: " + server);
      }
      else
      {
        server = args[0];
        if (!(rex.Match(server)).Success)
        {
          Console.WriteLine("Input string format not allowed.");
          return;
        }
      }

      // Get the list of the addresses associated with the requested server.
      IPAddresses(server);

      // Get additonal address information.
      IPAddressAdditionalInfo();
    }

  }
}

编辑

对我的 Win 10 机器的研究表明 IPv6 地址仅返回给本地主机，而不是带有 GetHostEntry 或 GetHostAddresses 的 Internet 主机。会看的更远。