Click here to Skip to main content
Click here to Skip to main content
Add your own
alternative version

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.vshost.exe
DnsDig.vshost.exe.manifest
nunit.framework.dll
DnsDig.csproj.user
DnsDig.AboutForm.resources
DnsDig.exe
DnsDig.MainForm.resources
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;
/*
 *  http://www.ietf.org/rfc/rfc2782.txt
 * 
   Priority
        The priority of this target host.  A client MUST attempt to
        contact the target host with the lowest-numbered priority it can
        reach; target hosts with the same priority SHOULD be tried in an
        order defined by the weight field.  The range is 0-65535.  This
        is a 16 bit unsigned integer in network byte order.

   Weight
        A server selection mechanism.  The weight field specifies a
        relative weight for entries with the same priority. Larger
        weights SHOULD be given a proportionately higher probability of
        being selected. The range of this number is 0-65535.  This is a
        16 bit unsigned integer in network byte order.  Domain
        administrators SHOULD use Weight 0 when there isn't any server
        selection to do, to make the RR easier to read for humans (less
        noisy).  In the presence of records containing weights greater
        than 0, records with weight 0 should have a very small chance of
        being selected.

        In the absence of a protocol whose specification calls for the
        use of other weighting information, a client arranges the SRV
        RRs of the same Priority in the order in which target hosts,
        specified by the SRV RRs, will be contacted. The following
        algorithm SHOULD be used to order the SRV RRs of the same
        priority:

        To select a target to be contacted next, arrange all SRV RRs
        (that have not been ordered yet) in any order, except that all
        those with weight 0 are placed at the beginning of the list.

        Compute the sum of the weights of those RRs, and with each RR
        associate the running sum in the selected order. Then choose a
        uniform random number between 0 and the sum computed
        (inclusive), and select the RR whose running sum value is the
        first in the selected order which is greater than or equal to
        the random number selected. The target host specified in the
        selected SRV RR is the next one to be contacted by the client.
        Remove this SRV RR from the set of the unordered SRV RRs and
        apply the described algorithm to the unordered SRV RRs to select
        the next target host.  Continue the ordering process until there
        are no unordered SRV RRs.  This process is repeated for each
        Priority.

   Port
        The port on this target host of this service.  The range is 0-
        65535.  This is a 16 bit unsigned integer in network byte order.
        This is often as specified in Assigned Numbers but need not be.

   Target
        The domain name of the target host.  There MUST be one or more
        address records for this name, the name MUST NOT be an alias (in
        the sense of RFC 1034 or RFC 2181).  Implementors are urged, but
        not required, to return the address record(s) in the Additional
        Data section.  Unless and until permitted by future standards
        action, name compression is not to be used for this field.

        A Target of "." means that the service is decidedly not
        available at this domain.

 */

namespace Heijden.DNS
{
	public class RecordSRV : Record
	{
		public ushort PRIORITY;
		public ushort WEIGHT;
		public ushort PORT;
		public string TARGET;

		public RecordSRV(RecordReader rr)
		{
			PRIORITY = rr.ReadUInt16();
			WEIGHT = rr.ReadUInt16();
			PORT = rr.ReadUInt16();
			TARGET = rr.ReadDomainName();
		}

		public override string ToString()
		{
			return string.Format("{0} {1} {2} {3}",
				PRIORITY,
				WEIGHT,
				PORT,
				TARGET);
		}

	}
}

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.

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)

| Advertise | Privacy | Mobile
Web04 | 2.8.140721.1 | Last Updated 11 Mar 2013
Article Copyright 2008 by Alphons van der Heijden
Everything else Copyright © CodeProject, 1999-2014
Terms of Service
Layout: fixed | fluid