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DNS.NET Resolver (C#)

, 11 Mar 2013
A full implementation of a reusable DNS resolver component and a Dig.Net example application.
Article_Demo.zip
Article_Demo
DnsDig.exe
nunit.framework.dll
article_src-noexe.zip
DnsDig
DnsDig.suo
DnsDig
bin
Debug
Article_Demo.zip
DnsDig.vshost.exe.manifest
Dns
Records
NotUsed
Obsolete
Root
DnsDig.csproj.user
Doc
obj
Debug
DnsDig.AboutForm.resources
DnsDig.MainForm.resources
DnsDig.Properties.Resources.resources
Properties
Settings.settings
article_src.zip
DnsDig.suo
Article_Demo.zip
DnsDig.exe
DnsDig.pdb
DnsDig.vshost.exe
DnsDig.vshost.exe.manifest
nunit.framework.dll
Release
DnsDig.csproj.user
DesignTimeResolveAssemblyReferencesInput.cache
DnsDig.AboutForm.resources
DnsDig.csproj.GenerateResource.Cache
DnsDig.csprojResolveAssemblyReference.cache
DnsDig.exe
DnsDig.MainForm.resources
DnsDig.pdb
DnsDig.Properties.Resources.resources
TempPE
Properties.Resources.Designer.cs.dll
Settings.settings
article_src.zip.zip
DnsDig.suo
DnsDig.csproj.user
DnsExperiment.AboutForm.resources
DnsExperiment.csproj.GenerateResource.Cache
DnsExperiment.MainForm.resources
DnsExperiment.Properties.Resources.resources
Refactor
Properties.Resources.Designer.cs.dll
Settings.settings
using System;

using System.Net;
using System.Diagnostics;

using Heijden.DNS;

using NUnit.Framework;

// Use: C:\Program Files\NUnit\bin\nunit.exe
// Open: dnsdig.exe
//
namespace DnsDig
{
	[TestFixture]
	public class NUnitTester
	{
		Resolver resolver;

		[SetUp]
		public void Init()
		{
			resolver = new Resolver();
		}

		[Test]
		public void Test1()
		{
			Stopwatch sw1 = new Stopwatch();
			Stopwatch sw2 = new Stopwatch();
			Stopwatch sw3 = new Stopwatch();

			// The .NET DNS class uses cached data
			// try > ipconfig /flushdns
			// this clears the cache, and shows real resolving
			sw1.Start();
			IPHostEntry e1 = Dns.GetHostEntry("www.microsoft.com");
			sw1.Stop();

			Console.WriteLine("Dns.GetHostEntry " + sw1.ElapsedMilliseconds + " mSec");

			sw2.Start();
			IPHostEntry e2 = resolver.GetHostEntry("www.microsoft.com");
			sw2.Stop();

			Console.WriteLine("resolver.GetHostEntry " + sw2.ElapsedMilliseconds + " mSec");

			sw3.Start();
			IPHostEntry e3 = resolver.GetHostEntry("www.microsoft.com");
			sw3.Stop();

			Console.WriteLine("resolver.GetHostEntry " + sw3.ElapsedMilliseconds + " mSec");
		}

		[Test]
		public void Test2()
		{
			Response response = resolver.Query("www.microsoft.com", QType.A);
			foreach (RecordA recordA in response.RecordsA)
			{
				Console.WriteLine("RecordA " + recordA.Address);

				// every record has a reference to its Resource Record
				Console.WriteLine("RR TTL " + recordA.RR.TTL);
			}

			// Asynd testing
			IAsyncResult ar = resolver.BeginGetHostEntry("www.microsoft.com", null, null);

			bool blnResult = ar.AsyncWaitHandle.WaitOne(5000, false);

			Console.WriteLine("Result {0}", blnResult);

			IPHostEntry iPHostEntry = resolver.EndGetHostEntry(ar);

			Console.WriteLine("EndGetHostEntry (via HostName) returns {0}", iPHostEntry.HostName);

			ar = resolver.BeginGetHostEntry(IPAddress.Parse("207.46.193.254"), null, null);

			blnResult = ar.AsyncWaitHandle.WaitOne(5000,false);

			Console.WriteLine("Result {0}", blnResult);

			iPHostEntry = resolver.EndGetHostEntry(ar);

			Console.WriteLine("EndGetHostEntry (via IP) returns {0}", iPHostEntry.HostName);

		}


		[Test]
		public void Test3()
		{
			Response resp1 = resolver.Query("microsoft.com", QType.MX);
			foreach (RecordMX recordMX in resp1.RecordsMX)
			{
				Console.WriteLine("RecordMX " + recordMX);
				Response resp2 = resolver.Query(recordMX.EXCHANGE, QType.A);
				foreach (RecordA recordA in resp2.RecordsA)
				{
					Console.WriteLine("->" + recordA);
				}
			}
		}

		[Test]
		public void TestGetArpaFromIp()
		{
			string s = "4321:0:1:2:3:4:567:89ab";

			string a = Resolver.GetArpaFromIp(IPAddress.Parse(s));

			Assert.AreEqual(a, "b.a.9.8.7.6.5.0.4.0.0.0.3.0.0.0.2.0.0.0.1.0.0.0.0.0.0.0.1.2.3.4.ip6.arpa.");
		}

		[Test]
		public void TestNaptr()
		{
			string TelephoneNumber = "+1 800-555-5555";
			//string TelephoneNumber = "+1 567-459-0088";
			Resolver resolver1 = new Resolver();
			resolver1.DnsServer = "E164.org";
			string strEnum = Resolver.GetArpaFromEnum(TelephoneNumber);

			Assert.AreEqual(strEnum, "5.5.5.5.5.5.5.0.0.8.1.e164.arpa.");
			//Assert.AreEqual(strEnum, "8.8.0.0.9.5.4.7.6.5.1.e164.arpa.");
			
			Response response = resolver1.Query(strEnum, QType.NAPTR, QClass.IN);
			foreach (RR rr in response.Answers)
				Console.WriteLine(rr.ToString());
		}

		[Test]
		[ExpectedException(typeof(ArgumentNullException))]
		public void TestGetHostByAddress1()
		{
			string s = null;
			resolver.GetHostByAddress(s);
		}

		[Test]
		[ExpectedException(typeof(NullReferenceException))]
		public void TestGetHostByAddress2()
		{
			IPAddress i = null;
			resolver.GetHostByAddress(i);
		}

	}
}

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License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Alphons van der Heijden
Retired Van der Heijden Holding BV
Netherlands Netherlands
I'm Alphons van der Heijden, living in Lelystad, Netherlands, Europa, Earth. And currently I'm retiring from hard working ( ;- ), owning my own company. Because I'm full of energy, and a little to young to relax ...., I don't sit down, but create and recreate software solutions, that I like. Reinventing the wheel is my second nature. My interest is in the area of Internet technologies, .NET etc. I was there in 1992 when Mosaic came out, and from that point, my life changed dramatically, and so did the world, in fact. (Y)

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