internal static DnsResourceData Read(DnsDatagram dns, DnsType type, int offsetInDns, int length)
{
DnsResourceData prototype = TryGetPrototype(type);
if (prototype != null)
{
return(prototype.CreateInstance(dns, offsetInDns, length));
}
return(new DnsResourceDataAnything(dns.Subsegment(offsetInDns, length)));
}
/// <summary>
/// Returns the DnsResourceData concrete type that should be created for the given DnsType.
/// </summary>
public static Type GetDnsResourceDataType(DnsType dnsType)
{
DnsResourceData prototype = TryGetPrototype(dnsType);
if (prototype == null)
{
return(null);
}
return(prototype.GetType());
}
internal static DnsDataResourceRecord Parse(DnsDatagram dns, int offsetInDns, out int numBytesRead)
{
DnsDomainName domainName;
DnsType type;
DnsClass dnsClass;
if (!TryParseBase(dns, offsetInDns, out domainName, out type, out dnsClass, out numBytesRead))
{
return(null);
}
if (offsetInDns + numBytesRead + MinimumLengthAfterBase > dns.Length)
{
return(null);
}
int ttl = dns.ReadInt(offsetInDns + numBytesRead + OffsetAfterBase.Ttl, Endianity.Big);
ushort dataLength = dns.ReadUShort(offsetInDns + numBytesRead + OffsetAfterBase.DataLength, Endianity.Big);
numBytesRead += MinimumLengthAfterBase;
if (offsetInDns + numBytesRead + dataLength > dns.Length)
{
return(null);
}
DnsResourceData data = DnsResourceData.Read(dns, type, offsetInDns + numBytesRead, dataLength);
if (data == null)
{
return(null);
}
numBytesRead += dataLength;
if (type == DnsType.Opt)
{
return(new DnsOptResourceRecord(domainName, dnsClass, ttl, data));
}
return(new DnsDataResourceRecord(domainName, type, dnsClass, ttl, data));
}
/// <summary>
/// Creates a resource record from domain name, type, class, ttl and data.
/// </summary>
/// <param name="domainName">An owner name, i.e., the name of the node to which this resource record pertains.</param>
/// <param name="type">Two octets containing one of the RR TYPE codes.</param>
/// <param name="dnsClass">Two octets containing one of the RR CLASS codes.</param>
/// <param name="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.
/// </param>
/// <param name="data">
/// A variable length string of octets that describes the resource.
/// The format of this information varies according to the TYPE and CLASS of the resource record.
/// For example, the if the TYPE is A and the CLASS is IN, the RDATA field is a 4 octet ARPA Internet address.
/// </param>
public DnsDataResourceRecord(DnsDomainName domainName, DnsType type, DnsClass dnsClass, int ttl, DnsResourceData data)
: base(domainName, type, dnsClass)
{
Ttl = ttl;
Data = data;
}
internal DnsOptResourceRecord(DnsDomainName domainName, DnsClass dnsClass, int ttl, DnsResourceData data)
: base(domainName, DnsType.Opt, dnsClass, ttl, data)
{
}