rawdns

type CompressedName struct {
	Offset    uint16
	IsPointer bool
}

type Header struct {

	// ID is an arbitrary 16bit request identifier that is
	// forwarded back in the response so that we can match them up.
	ID uint16

	// QR is an 1bit flag specifying whether this message is a query (0)
	// of a response (1)
	// 1bit
	QR byte

	// Opcode is a 4bit field that specifies the query type.
	// Possible values are:
	// 0		- standard query		(QUERY)
	// 1		- inverse query			(IQUERY)
	// 2		- server status request		(STATUS)
	// 3 to 15	- reserved for future use
	Opcode Opcode

	// AA indicates whether this is an (A)nswer from an (A)uthoritative
	// server.
	// Valid in responses only.
	// 1bit.
	AA byte

	// TC indicates whether the message was (T)run(C)ated due to the length
	// being grater than the permitted on the transmission channel.
	// 1bit.
	TC byte

	// RD indicates whether (R)ecursion is (D)esired or not.
	// 1bit.
	RD byte

	// RA indidicates whether (R)ecursion is (A)vailable or not.
	// 1bit.
	RA byte

	// Z is reserved for future use
	Z byte

	// RCODE contains the (R)esponse (CODE) - it's a 4bit field that is
	// set as part of responses.
	RCODE byte

	// QDCOUNT specifies the number of entries in the question section
	QDCOUNT uint16

	// ANCOUNT specifies the number of resource records (RR) in the answer
	// section
	ANCOUNT uint16

	// NSCOUNT specifies the number of name server resource records in the
	// authority section
	NSCOUNT uint16

	// ARCOUNT specifies the number of resource records in the additional
	// records section
	ARCOUNT uint16
}

type Message struct {

	// Header is always present. It includes fields
	// that specify which of the remaining sections
	// are present, and also specifies whether the
	// message is a query or a response, a standard
	// query of some other opcode etc
	Header

	// Question carries the "question" of the query,
	// defining parameters that determines what's
	// being asked.
	Questions []*Question

	// Answers encapsulates the resource records
	// retrieved when receiving answers from the
	// server queried.
	Answers []*RR
}

type Opcode byte

type QClass uint16

type QType uint16

type Question struct {
	// QNAME refers to the domain name to be resolved in the query.
	// It's represented as a sequence of labels where each label
	// consists
	QNAME string

	// QTYPE specifies the type of the query to perform.
	QTYPE QType

	// QCLASS
	QCLASS QClass
}

type RCODE byte

type RR struct {

	// NAME is the Domain name to which this resource record pertains.
	// It might either come in the compressed format or not, depending
	// on the server.
	// Typically this should come compressed (indicated by the first two
	// bits).
	NAME string

	// TYPE is the type of the RR. It specifies the meaning of the
	// data that RDATA contains.
	TYPE QType

	// CLASS identifies the class of the data holded on RDATA.
	CLASS QClass

	// TTL indicates the time interval in seconds that the resource
	// recorded may be cached before it should be discarded.
	TTL uint32

	// RDLENGTH specifies the length in octets of the RDATA field.
	// ps.: if there's a pointer in the RDATA, this length
	// will not count the final result (expanded), but the
	// actual amount in transfer.
	RDLENGTH uint16

	// RDATA is the generic data from the record.
	// The format of the information contained here varies
	// according to the tupple {TYPE, CLASS} of the RR.
	RDATA []byte
}