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DNS.NET Resolver (C#)

, 11 Mar 2013 CPOL
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.Collections.Generic;
using System.Text;

namespace Heijden.DNS
{
	public class RecordReader
	{
		private byte[] m_Data;
		private int m_Position;
		public RecordReader(byte[] data)
		{
			m_Data = data;
			m_Position = 0;
		}

		public int Position
		{
			get
			{
				return m_Position;
			}
			set
			{
				m_Position = value;
			}
		}

		public RecordReader(byte[] data, int Position)
		{
			m_Data = data;
			m_Position = Position;
		}


		public byte ReadByte()
		{
			if (m_Position >= m_Data.Length)
				return 0;
			else
				return m_Data[m_Position++];
		}

		public char ReadChar()
		{
			return (char)ReadByte();
		}

		public ushort ReadShort()
		{
			return (ushort)(ReadByte() << 8 | ReadByte());
		}

		public ushort ReadShort(int offset)
		{
			m_Position += offset;
			return ReadShort();
		}

		public int ReadInt()
		{
			return ReadShort()<<16 | ReadShort();
		}

		public string ReadDomainName()
		{
			StringBuilder name = new StringBuilder();
			int length = 0;

			// get  the length of the first label
			while ((length = ReadByte()) != 0)
			{
				// top 2 bits set denotes domain name compression and to reference elsewhere
				if ((length & 0xc0) == 0xc0)
				{
					// work out the existing domain name, copy this pointer
					RecordReader newRecordReader = new RecordReader(m_Data, (length & 0x3f) << 8 | ReadByte());

					name.Append(newRecordReader.ReadDomainName());
					return name.ToString();
				}

				// if not using compression, copy a char at a time to the domain name
				while (length > 0)
				{
					name.Append(ReadChar());
					length--;
				}
				name.Append('.');
			}
			if (name.Length == 0)
				return ".";
			else
				return name.ToString();
		}

		public string ReadString()
		{
			short length = this.ReadByte();

			StringBuilder name = new StringBuilder();
			for(int intI=0;intI<length;intI++)
				name.Append(ReadChar());
			return name.ToString();
		}

		public byte[] ReadBytes(int intLength)
		{
			List<byte> list = new List<byte>();
			for(int intI=0;intI<intLength;intI++)
				list.Add(ReadByte());
			return list.ToArray();
		}

		public Record ReadRecord(Type type)
		{
			switch (type)
			{
				case Type.A:
					return new RecordA(this);
				case Type.NS:
					return new RecordNS(this);
				case Type.CNAME:
					return new RecordCNAME(this);
				case Type.SOA:
					return new RecordSOA(this);
				case Type.PTR:
					return new RecordPTR(this);
				case Type.HINFO:
					return new RecordHINFO(this);
				case Type.MINFO:
					return new RecordMINFO(this);
				case Type.MX:
					return new RecordMX(this);
				case Type.TXT:
					return new RecordTXT(this);

				// old stuff
				case Type.MD:
					return new RecordMD(this);
				case Type.MF:
					return new RecordMF(this);
				case Type.MB:
					return new RecordMB(this);
				case Type.MG:
					return new RecordMG(this);
				case Type.MR:
					return new RecordMR(this);
				case Type.NULL:
					return new RecordNULL(this);
				case Type.WKS:
					return new RecordWKS(this);

				// RFC 1886 IPV6
				case Type.AAAA:
					return new RecordAAAA(this);

				default:
					return new RecordUnknown(this);
			}
		}

	}
}

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

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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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