dnsmessage

Imports

Imports #

"errors"

Constants & Variables

ClassANY const #

Question.Class

const ClassANY Class = 255

ClassCHAOS const #

const ClassCHAOS Class = 3

ClassCSNET const #

const ClassCSNET Class = 2

ClassHESIOD const #

const ClassHESIOD Class = 4

ClassINET const #

ResourceHeader.Class and Question.Class

const ClassINET Class = 1

ErrNotStarted var #

ErrNotStarted indicates that the prerequisite information isn't available yet because the previous records haven't been appropriately parsed, skipped or finished.

var ErrNotStarted = *ast.CallExpr

ErrSectionDone var #

ErrSectionDone indicated that all records in the section have been parsed or finished.

var ErrSectionDone = *ast.CallExpr

RCodeFormatError const #

Header.RCode values.

const RCodeFormatError RCode = 1

RCodeNameError const #

Header.RCode values.

const RCodeNameError RCode = 3

RCodeNotImplemented const #

Header.RCode values.

const RCodeNotImplemented RCode = 4

RCodeRefused const #

Header.RCode values.

const RCodeRefused RCode = 5

RCodeServerFailure const #

Header.RCode values.

const RCodeServerFailure RCode = 2

RCodeSuccess const #

Header.RCode values.

const RCodeSuccess RCode = 0

TypeA const #

ResourceHeader.Type and Question.Type

const TypeA Type = 1

TypeAAAA const #

const TypeAAAA Type = 28

TypeALL const #

const TypeALL Type = 255

TypeAXFR const #

const TypeAXFR Type = 252

TypeCNAME const #

const TypeCNAME Type = 5

TypeHINFO const #

const TypeHINFO Type = 13

TypeMINFO const #

const TypeMINFO Type = 14

TypeMX const #

const TypeMX Type = 15

TypeNS const #

const TypeNS Type = 2

TypeOPT const #

const TypeOPT Type = 41

TypePTR const #

const TypePTR Type = 12

TypeSOA const #

const TypeSOA Type = 6

TypeSRV const #

const TypeSRV Type = 33

TypeTXT const #

const TypeTXT Type = 16

TypeWKS const #

Question.Type

const TypeWKS Type = 11

classNames var #

var classNames = map[Class]string{...}

edns0DNSSECOK const #

EDNS(0) wire constants.

const edns0DNSSECOK = 0x00008000

edns0DNSSECOKMask const #

EDNS(0) wire constants.

const edns0DNSSECOKMask = 0x00ff8000

edns0Version const #

EDNS(0) wire constants.

const edns0Version = 0

ednsVersionMask const #

EDNS(0) wire constants.

const ednsVersionMask = 0x00ff0000

errBaseLen var #

var errBaseLen = *ast.CallExpr

errCalcLen var #

var errCalcLen = *ast.CallExpr

errInvalidName var #

var errInvalidName = *ast.CallExpr

errInvalidPtr var #

var errInvalidPtr = *ast.CallExpr

errNameTooLong var #

var errNameTooLong = *ast.CallExpr

errNilResouceBody var #

var errNilResouceBody = *ast.CallExpr

errNonCanonicalName var #

var errNonCanonicalName = *ast.CallExpr

errResTooLong var #

var errResTooLong = *ast.CallExpr

errReserved var #

var errReserved = *ast.CallExpr

errResourceLen var #

var errResourceLen = *ast.CallExpr

errSegTooLong var #

var errSegTooLong = *ast.CallExpr

errStringTooLong var #

var errStringTooLong = *ast.CallExpr

errTooManyAdditionals var #

var errTooManyAdditionals = *ast.CallExpr

errTooManyAnswers var #

var errTooManyAnswers = *ast.CallExpr

errTooManyAuthorities var #

var errTooManyAuthorities = *ast.CallExpr

errTooManyPtr var #

var errTooManyPtr = *ast.CallExpr

errTooManyQuestions var #

var errTooManyQuestions = *ast.CallExpr

errZeroSegLen var #

var errZeroSegLen = *ast.CallExpr

headerBitAA const #

const headerBitAA = *ast.BinaryExpr

headerBitAD const #

const headerBitAD = *ast.BinaryExpr

headerBitCD const #

const headerBitCD = *ast.BinaryExpr

headerBitQR const #

const headerBitQR = *ast.BinaryExpr

headerBitRA const #

const headerBitRA = *ast.BinaryExpr

headerBitRD const #

const headerBitRD = *ast.BinaryExpr

headerBitTC const #

const headerBitTC = *ast.BinaryExpr

headerLen const #

headerLen is the length (in bytes) of a DNS header. A header is comprised of 6 uint16s and no padding.

const headerLen = *ast.BinaryExpr

hexDigits const #

const hexDigits = "0123456789abcdef"

nonEncodedNameMax const #

const nonEncodedNameMax = 254

packStartingCap const #

packStartingCap is the default initial buffer size allocated during packing. The starting capacity doesn't matter too much, but most DNS responses Will be <= 512 bytes as it is the limit for DNS over UDP.

const packStartingCap = 512

rCodeNames var #

var rCodeNames = map[RCode]string{...}

sectionAdditionals const #

const sectionAdditionals

sectionAnswers const #

const sectionAnswers

sectionAuthorities const #

const sectionAuthorities

sectionDone const #

const sectionDone

sectionHeader const #

const sectionHeader

sectionNames var #

var sectionNames = map[section]string{...}

sectionNotStarted const #

const sectionNotStarted section = iota

sectionQuestions const #

const sectionQuestions

typeNames var #

var typeNames = map[Type]string{...}

uint16Len const #

uint16Len is the length (in bytes) of a uint16.

const uint16Len = 2

uint32Len const #

uint32Len is the length (in bytes) of a uint32.

const uint32Len = 4

Type Aliases

Class type #

A Class is a type of network.

type Class uint16

OpCode type #

An OpCode is a DNS operation code.

type OpCode uint16

RCode type #

An RCode is a DNS response status code.

type RCode uint16

Type type #

A Type is a type of DNS request and response.

type Type uint16

section type #

type section uint8

Interfaces

ResourceBody interface #

A ResourceBody is a DNS resource record minus the header.

type ResourceBody interface {
pack(msg []byte, compression map[string]uint16, compressionOff int) ([]byte, error)
realType() Type
GoString() string
}

Structs

AAAAResource struct #

An AAAAResource is an AAAA Resource record.

type AAAAResource struct {
AAAA [16]byte
}

AResource struct #

An AResource is an A Resource record.

type AResource struct {
A [4]byte
}

Builder struct #

A Builder allows incrementally packing a DNS message. Example usage: buf := make([]byte, 2, 514) b := NewBuilder(buf, Header{...}) b.EnableCompression() // Optionally start a section and add things to that section. // Repeat adding sections as necessary. buf, err := b.Finish() // If err is nil, buf[2:] will contain the built bytes.

type Builder struct {
msg []byte
section section
header header
start int
compression map[string]uint16
}

CNAMEResource struct #

A CNAMEResource is a CNAME Resource record.

type CNAMEResource struct {
CNAME Name
}

Header struct #

Header is a representation of a DNS message header.

type Header struct {
ID uint16
Response bool
OpCode OpCode
Authoritative bool
Truncated bool
RecursionDesired bool
RecursionAvailable bool
AuthenticData bool
CheckingDisabled bool
RCode RCode
}

MXResource struct #

An MXResource is an MX Resource record.

type MXResource struct {
Pref uint16
MX Name
}

Message struct #

Message is a representation of a DNS message.

type Message struct {
Header
Questions []Question
Answers []Resource
Authorities []Resource
Additionals []Resource
}

NSResource struct #

An NSResource is an NS Resource record.

type NSResource struct {
NS Name
}

Name struct #

A Name is a non-encoded and non-escaped domain name. It is used instead of strings to avoid allocations.

type Name struct {
Data [255]byte
Length uint8
}

OPTResource struct #

An OPTResource is an OPT pseudo Resource record. The pseudo resource record is part of the extension mechanisms for DNS as defined in RFC 6891.

type OPTResource struct {
Options []Option
}

Option struct #

An Option represents a DNS message option within OPTResource. The message option is part of the extension mechanisms for DNS as defined in RFC 6891.

type Option struct {
Code uint16
Data []byte
}

PTRResource struct #

A PTRResource is a PTR Resource record.

type PTRResource struct {
PTR Name
}

Parser struct #

A Parser allows incrementally parsing a DNS message. When parsing is started, the Header is parsed. Next, each Question can be either parsed or skipped. Alternatively, all Questions can be skipped at once. When all Questions have been parsed, attempting to parse Questions will return the [ErrSectionDone] error. After all Questions have been either parsed or skipped, all Answers, Authorities and Additionals can be either parsed or skipped in the same way, and each type of Resource must be fully parsed or skipped before proceeding to the next type of Resource. Parser is safe to copy to preserve the parsing state. Note that there is no requirement to fully skip or parse the message.

type Parser struct {
msg []byte
header header
section section
off int
index int
resHeaderValid bool
resHeaderOffset int
resHeaderType Type
resHeaderLength uint16
}

Question struct #

A Question is a DNS query.

type Question struct {
Name Name
Type Type
Class Class
}

Resource struct #

A Resource is a DNS resource record.

type Resource struct {
Header ResourceHeader
Body ResourceBody
}

ResourceHeader struct #

A ResourceHeader is the header of a DNS resource record. There are many types of DNS resource records, but they all share the same header.

type ResourceHeader struct {
Name Name
Type Type
Class Class
TTL uint32
Length uint16
}

SOAResource struct #

An SOAResource is an SOA Resource record.

type SOAResource struct {
NS Name
MBox Name
Serial uint32
Refresh uint32
Retry uint32
Expire uint32
MinTTL uint32
}

SRVResource struct #

An SRVResource is an SRV Resource record.

type SRVResource struct {
Priority uint16
Weight uint16
Port uint16
Target Name
}

TXTResource struct #

A TXTResource is a TXT Resource record.

type TXTResource struct {
TXT []string
}

UnknownResource struct #

An UnknownResource is a catch-all container for unknown record types.

type UnknownResource struct {
Type Type
Data []byte
}

header struct #

header is the wire format for a DNS message header.

type header struct {
id uint16
bits uint16
questions uint16
answers uint16
authorities uint16
additionals uint16
}

nestedError struct #

type nestedError struct {
s string
err error
}

Functions

AAAAResource method #

AAAAResource parses a single AAAAResource. One of the XXXHeader methods must have been called before calling this method.

func (p *Parser) AAAAResource() (AAAAResource, error)

AAAAResource method #

AAAAResource adds a single AAAAResource.

func (b *Builder) AAAAResource(h ResourceHeader, r AAAAResource) error

AResource method #

AResource parses a single AResource. One of the XXXHeader methods must have been called before calling this method.

func (p *Parser) AResource() (AResource, error)

AResource method #

AResource adds a single AResource.

func (b *Builder) AResource(h ResourceHeader, r AResource) error

Additional method #

Additional parses a single Additional Resource.

func (p *Parser) Additional() (Resource, error)

AdditionalHeader method #

AdditionalHeader parses a single Additional ResourceHeader.

func (p *Parser) AdditionalHeader() (ResourceHeader, error)

AllAdditionals method #

AllAdditionals parses all Additional Resources.

func (p *Parser) AllAdditionals() ([]Resource, error)

AllAnswers method #

AllAnswers parses all Answer Resources.

func (p *Parser) AllAnswers() ([]Resource, error)

AllAuthorities method #

AllAuthorities parses all Authority Resources.

func (p *Parser) AllAuthorities() ([]Resource, error)

AllQuestions method #

AllQuestions parses all Questions.

func (p *Parser) AllQuestions() ([]Question, error)

Answer method #

Answer parses a single Answer Resource.

func (p *Parser) Answer() (Resource, error)

AnswerHeader method #

AnswerHeader parses a single Answer ResourceHeader.

func (p *Parser) AnswerHeader() (ResourceHeader, error)

AppendPack method #

AppendPack is like Pack but appends the full Message to b and returns the extended buffer.

func (m *Message) AppendPack(b []byte) ([]byte, error)

Authority method #

Authority parses a single Authority Resource.

func (p *Parser) Authority() (Resource, error)

AuthorityHeader method #

AuthorityHeader parses a single Authority ResourceHeader.

func (p *Parser) AuthorityHeader() (ResourceHeader, error)

CNAMEResource method #

CNAMEResource adds a single CNAMEResource.

func (b *Builder) CNAMEResource(h ResourceHeader, r CNAMEResource) error

CNAMEResource method #

CNAMEResource parses a single CNAMEResource. One of the XXXHeader methods must have been called before calling this method.

func (p *Parser) CNAMEResource() (CNAMEResource, error)

DNSSECAllowed method #

DNSSECAllowed reports whether the DNSSEC OK bit is set.

func (h *ResourceHeader) DNSSECAllowed() bool

EnableCompression method #

EnableCompression enables compression in the Builder. Leaving compression disabled avoids compression related allocations, but can result in larger message sizes. Be careful with this mode as it can cause messages to exceed the UDP size limit. According to RFC 1035, section 4.1.4, the use of compression is optional, but all implementations must accept both compressed and uncompressed DNS messages. Compression should be enabled before any sections are added for best results.

func (b *Builder) EnableCompression()

Error method #

nestedError implements error.Error.

func (e *nestedError) Error() string

ExtendedRCode method #

ExtendedRCode returns an extended RCode. The provided rcode must be the RCode in DNS message header.

func (h *ResourceHeader) ExtendedRCode(rcode RCode) RCode