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* Copyright (c) 2010, j. montgomery *
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using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Net;
using DnDns.Enums;
namespace DnDns.Records
{
///
/// The DnsRecordHeader class contains fields, properties and
/// parsing cababilities within the DNS Record except the the
/// RDATA. The Name, Type, Class, TTL, and RDLength.
///
/// This class is used in the DnsRecordFactory to instantiate
/// concrete DnsRecord Classes.
///
/// RFC 1035
///
/// 3.2.1. Format
///
/// All RRs have the same top level format shown below:
///
/// 1 1 1 1 1 1
/// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/// | |
/// / /
/// / NAME /
/// | |
/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/// | TYPE |
/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/// | CLASS |
/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/// | TTL |
/// | |
/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/// | RDLENGTH |
/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--|
///
/// where:
///
/// NAME an owner name, i.e., the name of the node to which this
/// resource record pertains.
///
/// TYPE two octets containing one of the RR TYPE codes.
///
/// CLASS two octets containing one of the RR CLASS codes.
///
/// TTL a 32 bit signed integer that specifies the time interval
/// that the resource record may be cached before the source
/// of the information should again be consulted. Zero
/// values are interpreted to mean that the RR can only be
/// used for the transaction in progress, and should not be
/// cached. For example, SOA records are always distributed
/// with a zero TTL to prohibit caching. Zero values can
/// also be used for extremely volatile data.
///
/// RDLENGTH an unsigned 16 bit integer that specifies the length in
/// octets of the RDATA field.
///
///
public class RecordHeader
{
#region Fields
// NAME an owner name, i.e., the name of the node to which this
// resource record pertains.
private string _name;
// TYPE two octets containing one of the RR TYPE codes.
private NsType _nsType;
// CLASS - two octets containing one of the RR CLASS codes.
private NsClass _nsClass;
// TTL - a 32 bit signed integer that specifies the time interval
// that the resource record may be cached before the source
// of the information should again be consulted. Zero
// values are interpreted to mean that the RR can only be
// used for the transaction in progress, and should not be
// cached. For example, SOA records are always distributed
// with a zero TTL to prohibit caching. Zero values can
/// also be used for extremely volatile data.
private int _timeToLive;
// RDLENGTH - an unsigned 16 bit integer that specifies the length in
// octets of the RDATA field.
private short _dataLength;
///
/// Initalise the
///
/// The header name
/// The resource type
/// The class type
/// The time to live
public RecordHeader(string name, NsType nsType, NsClass nsClass, int timeToLive)
{
_name = name;
_nsType = nsType;
_nsClass = nsClass;
_timeToLive = timeToLive;
}
public RecordHeader()
{
}
#endregion
#region Properties
///
/// NAME - an owner name, i.e., the name of the node to which this
/// resource record pertains.
///
public string Name
{
get { return _name; }
}
///
/// TYPE two octets containing one of the RR TYPE codes.
///
public NsType NsType
{
get { return _nsType; }
}
///
/// CLASS - two octets containing one of the RR CLASS codes.
///
public NsClass NsClass
{
get { return _nsClass; }
}
///
/// TTL - a 32 bit signed integer that specifies the time interval
/// that the resource record may be cached before the source
/// of the information should again be consulted. Zero
/// values are interpreted to mean that the RR can only be
/// used for the transaction in progress, and should not be
/// cached. For example, SOA records are always distributed
/// with a zero TTL to prohibit caching. Zero values can
/// also be used for extremely volatile data.
///
public int TimeToLive
{
get { return _timeToLive; }
}
///
/// RDLENGTH - an unsigned 16 bit integer that specifies the length in
/// octets of the RDATA field.
///
public short DataLength
{
get { return _dataLength; }
}
#endregion
///
///
///
///
public void ParseRecordHeader(ref MemoryStream ms)
{
byte[] nsType = new byte[2];
byte[] nsClass = new byte[2];
byte[] nsTTL = new byte[4];
byte[] nsDataLength = new byte[2];
// Read the name
_name = DnsRecordBase.ParseName(ref ms);
// Read the data header
ms.Read(nsType, 0, 2);
ms.Read(nsClass, 0, 2);
ms.Read(nsTTL, 0, 4);
ms.Read(nsDataLength, 0, 2);
_nsType = (NsType)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(nsType, 0));
_nsClass = (NsClass)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(nsClass, 0));
_timeToLive = IPAddress.NetworkToHostOrder(BitConverter.ToInt32(nsTTL, 0));
_dataLength = IPAddress.NetworkToHostOrder(BitConverter.ToInt16(nsDataLength, 0));
}
internal byte[] GetMessageBytes()
{
MemoryStream memoryStream = new MemoryStream();
byte[] data = DnsHelpers.CanonicaliseDnsName(_name, false);
memoryStream.Write(data,0,data.Length);
data = BitConverter.GetBytes((ushort)(IPAddress.HostToNetworkOrder((ushort)_nsType) >> 16));
memoryStream.Write(data, 0, data.Length);
data = BitConverter.GetBytes((ushort)(IPAddress.HostToNetworkOrder((ushort)_nsClass) >> 16));
memoryStream.Write(data, 0, data.Length);
data = BitConverter.GetBytes((uint)(IPAddress.HostToNetworkOrder((ushort)_timeToLive) >> 32));
memoryStream.Write(data, 0, data.Length);
data = BitConverter.GetBytes((ushort)(IPAddress.HostToNetworkOrder((ushort)_dataLength) >> 16));
memoryStream.Write(data, 0, data.Length);
return memoryStream.ToArray();
}
}
}