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@Nico-VanHaaster
Last active July 28, 2020 18:51
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Cancel DNS.BeginGetHostEntry
using System;
using System.Net;
using System.Threading.Tasks;
namespace DnsLookup
{
class Program
{
static void Main(string[] args)
{
ResolveTest("asdfasdfasdfasdfasdfa.ca", 15);
ResolveTest("google.com", 15);
RunTest();
Console.ReadLine();
}
public static async void RunTest()
{
await Resolve("asdfasdfasdfasdfasdfa.ca", 60);
await Resolve("google.com", 60);
}
public static Task<IPHostEntry> GetHostEntryAsync(string hostNameOrAddress)
{
return Task<IPHostEntry>.Factory.FromAsync<string>(new Func<string, AsyncCallback, object, IAsyncResult>(Dns.BeginGetHostEntry), new Func<IAsyncResult, IPHostEntry>(Dns.EndGetHostEntry), hostNameOrAddress, null);
}
public static bool ResolveTest(string hostNameOrAddress, int millisecond_time_out)
{
ResolveState ioContext = new ResolveState(hostNameOrAddress);
var result = Dns.BeginGetHostEntry(ioContext.HostName, null, null);
var success = result.AsyncWaitHandle.WaitOne(TimeSpan.FromMilliseconds(millisecond_time_out), true);
if (!success)
{
ioContext.Result = ResolveType.Timeout;
}
else
{
try
{
var ipList = Dns.EndGetHostEntry(result);
if (ipList == null || ipList.AddressList == null || ipList.AddressList.Length == 0)
ioContext.Result = ResolveType.InvalidHost;
else
ioContext.Result = ResolveType.Completed;
}
catch
{
ioContext.Result = ResolveType.InvalidHost;
}
}
Console.WriteLine($"The result of ResolveTest for {ioContext.HostName} is {ioContext.Result}");
return ioContext.Result == ResolveType.Completed;
}
public static Task<bool> Resolve(string hostNameOrAddress, int millisecond_time_out)
{
return Task.Run(async () =>
{
bool completed = false;
var asCallBack = new AsyncCallback(ar =>
{
ResolveState context = (ResolveState)ar.AsyncState;
if (context.Result == ResolveType.Pending)
{
try
{
var ipList = Dns.EndGetHostEntry(ar);
if (ipList == null || ipList.AddressList == null || ipList.AddressList.Length == 0)
context.Result = ResolveType.InvalidHost;
else
context.Result = ResolveType.Completed;
}
catch
{
context.Result = ResolveType.InvalidHost;
}
}
completed = true;
});
ResolveState ioContext = new ResolveState(hostNameOrAddress);
var result = Dns.BeginGetHostEntry(ioContext.HostName, asCallBack, ioContext);
int miliCount = 0;
while (!completed)
{
miliCount++;
if (miliCount >= millisecond_time_out)
{
result.AsyncWaitHandle.Close();
result = null;
ioContext.Result = ResolveType.Timeout;
break;
}
await Task.Delay(1);
}
Console.WriteLine($"The result of Resolve for {ioContext.HostName} is {ioContext.Result}");
return ioContext.Result == ResolveType.Completed;
});
}
public class ResolveState
{
public ResolveState(string hostName)
{
if (string.IsNullOrWhiteSpace(hostName))
throw new ArgumentNullException(nameof(hostName));
_hostName = hostName;
}
readonly string _hostName;
public ResolveType Result { get; set; } = ResolveType.Pending;
public string HostName => _hostName;
}
public enum ResolveType
{
Pending,
Completed,
InvalidHost,
Timeout
}
}
}
@Nico-VanHaaster
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Author

Updated and added ResolveTest

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