/// <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>
/// 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>
/// 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();
}
