/// <summary>
/// Construct a resource record from a pointer to a byte array
/// </summary>
/// <param name="pointer">the position in the byte array of the record</param>
internal ResourceRecord(Pointer pointer)
{
// extract the domain, question type, question class and Ttl
_domain = pointer.ReadDomain();
_dnsType = (DnsType)pointer.ReadShort();
_dnsClass = (DnsClass)pointer.ReadShort();
_Ttl = pointer.ReadInt();
// the next short is the record length, we only use it for unrecognised record types
int recordLength = pointer.ReadShort();
// and create the appropriate RDATA record based on the dnsType
switch (_dnsType)
{
case DnsType.NS: _record = new NSRecord(pointer); break;
case DnsType.MX: _record = new MXRecord(pointer); break;
case DnsType.ANAME: _record = new ANameRecord(pointer); break;
case DnsType.SOA: _record = new SoaRecord(pointer); break;
default:
{
// move the pointer over this unrecognised record
pointer += recordLength;
break;
}
}
}
/// <summary>
/// Construct the question reading from a DNS Server response. Consult RFC1035 4.1.2
/// for byte-wise details of this structure in byte array form
/// </summary>
/// <param name="pointer">a logical pointer to the Question in byte array form</param>
internal Question(Pointer pointer)
{
// extract from the message
_domain = pointer.ReadDomain();
_dnsType = (DnsType)pointer.ReadShort();
_dnsClass = (DnsClass)pointer.ReadShort();
}
/// <summary>
/// Constructs an MX record by reading bytes from a return message
/// </summary>
/// <param name="pointer">A logical pointer to the bytes holding the record</param>
internal MXRecord(Pointer pointer)
{
_preference = pointer.ReadShort();
_domainName = pointer.ReadDomain();
}
