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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.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 int Length
		{
			get
			{
				if (m_Data == null)
					return 0;
				else
					return m_Data.Length;
			}
		}

		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 UInt16 ReadUInt16()
		{
			return (UInt16)(ReadByte() << 8 | ReadByte());
		}

		public UInt16 ReadUInt16(int offset)
		{
			m_Position += offset;
			return ReadUInt16();
		}

		public UInt32 ReadUInt32()
		{
			return (UInt32)(ReadUInt16() << 16 | ReadUInt16());
		}

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

		// changed 28 augustus 2008
		public byte[] ReadBytes(int intLength)
		{
			byte[] list = new byte[intLength];
			for (int intI = 0; intI < intLength; intI++)
				list[intI] = ReadByte();
			return list;
		}

		public Record ReadRecord(Type type, int Length)
		{
			switch (type)
			{
				case Type.A:
					return new RecordA(this);
				case Type.NS:
					return new RecordNS(this);
				case Type.MD:
					return new RecordMD(this);
				case Type.MF:
					return new RecordMF(this);
				case Type.CNAME:
					return new RecordCNAME(this);
				case Type.SOA:
					return new RecordSOA(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);
				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, Length);
				case Type.RP:
					return new RecordRP(this);
				case Type.AFSDB:
					return new RecordAFSDB(this);
				case Type.X25:
					return new RecordX25(this);
				case Type.ISDN:
					return new RecordISDN(this);
				case Type.RT:
					return new RecordRT(this);
				case Type.NSAP:
					return new RecordNSAP(this);
				case Type.NSAPPTR:
					return new RecordNSAPPTR(this);
				case Type.SIG:
					return new RecordSIG(this);
				case Type.KEY:
					return new RecordKEY(this);
				case Type.PX:
					return new RecordPX(this);
				case Type.GPOS:
					return new RecordGPOS(this);
				case Type.AAAA:
					return new RecordAAAA(this);
				case Type.LOC:
					return new RecordLOC(this);
				case Type.NXT:
					return new RecordNXT(this);
				case Type.EID:
					return new RecordEID(this);
				case Type.NIMLOC:
					return new RecordNIMLOC(this);
				case Type.SRV:
					return new RecordSRV(this);
				case Type.ATMA:
					return new RecordATMA(this);
				case Type.NAPTR:
					return new RecordNAPTR(this);
				case Type.KX:
					return new RecordKX(this);
				case Type.CERT:
					return new RecordCERT(this);
				case Type.A6:
					return new RecordA6(this);
				case Type.DNAME:
					return new RecordDNAME(this);
				case Type.SINK:
					return new RecordSINK(this);
				case Type.OPT:
					return new RecordOPT(this);
				case Type.APL:
					return new RecordAPL(this);
				case Type.DS:
					return new RecordDS(this);
				case Type.SSHFP:
					return new RecordSSHFP(this);
				case Type.IPSECKEY:
					return new RecordIPSECKEY(this);
				case Type.RRSIG:
					return new RecordRRSIG(this);
				case Type.NSEC:
					return new RecordNSEC(this);
				case Type.DNSKEY:
					return new RecordDNSKEY(this);
				case Type.DHCID:
					return new RecordDHCID(this);
				case Type.NSEC3:
					return new RecordNSEC3(this);
				case Type.NSEC3PARAM:
					return new RecordNSEC3PARAM(this);
				case Type.HIP:
					return new RecordHIP(this);
				case Type.SPF:
					return new RecordSPF(this);
				case Type.UINFO:
					return new RecordUINFO(this);
				case Type.UID:
					return new RecordUID(this);
				case Type.GID:
					return new RecordGID(this);
				case Type.UNSPEC:
					return new RecordUNSPEC(this);
				case Type.TKEY:
					return new RecordTKEY(this);
				case Type.TSIG:
					return new RecordTSIG(this);
				default:
					return new RecordUnknown(this);
			}
		}

	}
}

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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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