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-rw-r--r--vendor/golang.org/x/net/dns/dnsmessage/message.go2606
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diff --git a/vendor/golang.org/x/net/dns/dnsmessage/message.go b/vendor/golang.org/x/net/dns/dnsmessage/message.go
new file mode 100644
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--- /dev/null
+++ b/vendor/golang.org/x/net/dns/dnsmessage/message.go
@@ -0,0 +1,2606 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package dnsmessage provides a mostly RFC 1035 compliant implementation of
+// DNS message packing and unpacking.
+//
+// The package also supports messages with Extension Mechanisms for DNS
+// (EDNS(0)) as defined in RFC 6891.
+//
+// This implementation is designed to minimize heap allocations and avoid
+// unnecessary packing and unpacking as much as possible.
+package dnsmessage
+
+import (
+ "errors"
+)
+
+// Message formats
+
+// A Type is a type of DNS request and response.
+type Type uint16
+
+const (
+ // ResourceHeader.Type and Question.Type
+ TypeA Type = 1
+ TypeNS Type = 2
+ TypeCNAME Type = 5
+ TypeSOA Type = 6
+ TypePTR Type = 12
+ TypeMX Type = 15
+ TypeTXT Type = 16
+ TypeAAAA Type = 28
+ TypeSRV Type = 33
+ TypeOPT Type = 41
+
+ // Question.Type
+ TypeWKS Type = 11
+ TypeHINFO Type = 13
+ TypeMINFO Type = 14
+ TypeAXFR Type = 252
+ TypeALL Type = 255
+)
+
+var typeNames = map[Type]string{
+ TypeA: "TypeA",
+ TypeNS: "TypeNS",
+ TypeCNAME: "TypeCNAME",
+ TypeSOA: "TypeSOA",
+ TypePTR: "TypePTR",
+ TypeMX: "TypeMX",
+ TypeTXT: "TypeTXT",
+ TypeAAAA: "TypeAAAA",
+ TypeSRV: "TypeSRV",
+ TypeOPT: "TypeOPT",
+ TypeWKS: "TypeWKS",
+ TypeHINFO: "TypeHINFO",
+ TypeMINFO: "TypeMINFO",
+ TypeAXFR: "TypeAXFR",
+ TypeALL: "TypeALL",
+}
+
+// String implements fmt.Stringer.String.
+func (t Type) String() string {
+ if n, ok := typeNames[t]; ok {
+ return n
+ }
+ return printUint16(uint16(t))
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (t Type) GoString() string {
+ if n, ok := typeNames[t]; ok {
+ return "dnsmessage." + n
+ }
+ return printUint16(uint16(t))
+}
+
+// A Class is a type of network.
+type Class uint16
+
+const (
+ // ResourceHeader.Class and Question.Class
+ ClassINET Class = 1
+ ClassCSNET Class = 2
+ ClassCHAOS Class = 3
+ ClassHESIOD Class = 4
+
+ // Question.Class
+ ClassANY Class = 255
+)
+
+var classNames = map[Class]string{
+ ClassINET: "ClassINET",
+ ClassCSNET: "ClassCSNET",
+ ClassCHAOS: "ClassCHAOS",
+ ClassHESIOD: "ClassHESIOD",
+ ClassANY: "ClassANY",
+}
+
+// String implements fmt.Stringer.String.
+func (c Class) String() string {
+ if n, ok := classNames[c]; ok {
+ return n
+ }
+ return printUint16(uint16(c))
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (c Class) GoString() string {
+ if n, ok := classNames[c]; ok {
+ return "dnsmessage." + n
+ }
+ return printUint16(uint16(c))
+}
+
+// An OpCode is a DNS operation code.
+type OpCode uint16
+
+// GoString implements fmt.GoStringer.GoString.
+func (o OpCode) GoString() string {
+ return printUint16(uint16(o))
+}
+
+// An RCode is a DNS response status code.
+type RCode uint16
+
+const (
+ // Message.Rcode
+ RCodeSuccess RCode = 0
+ RCodeFormatError RCode = 1
+ RCodeServerFailure RCode = 2
+ RCodeNameError RCode = 3
+ RCodeNotImplemented RCode = 4
+ RCodeRefused RCode = 5
+)
+
+var rCodeNames = map[RCode]string{
+ RCodeSuccess: "RCodeSuccess",
+ RCodeFormatError: "RCodeFormatError",
+ RCodeServerFailure: "RCodeServerFailure",
+ RCodeNameError: "RCodeNameError",
+ RCodeNotImplemented: "RCodeNotImplemented",
+ RCodeRefused: "RCodeRefused",
+}
+
+// String implements fmt.Stringer.String.
+func (r RCode) String() string {
+ if n, ok := rCodeNames[r]; ok {
+ return n
+ }
+ return printUint16(uint16(r))
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (r RCode) GoString() string {
+ if n, ok := rCodeNames[r]; ok {
+ return "dnsmessage." + n
+ }
+ return printUint16(uint16(r))
+}
+
+func printPaddedUint8(i uint8) string {
+ b := byte(i)
+ return string([]byte{
+ b/100 + '0',
+ b/10%10 + '0',
+ b%10 + '0',
+ })
+}
+
+func printUint8Bytes(buf []byte, i uint8) []byte {
+ b := byte(i)
+ if i >= 100 {
+ buf = append(buf, b/100+'0')
+ }
+ if i >= 10 {
+ buf = append(buf, b/10%10+'0')
+ }
+ return append(buf, b%10+'0')
+}
+
+func printByteSlice(b []byte) string {
+ if len(b) == 0 {
+ return ""
+ }
+ buf := make([]byte, 0, 5*len(b))
+ buf = printUint8Bytes(buf, uint8(b[0]))
+ for _, n := range b[1:] {
+ buf = append(buf, ',', ' ')
+ buf = printUint8Bytes(buf, uint8(n))
+ }
+ return string(buf)
+}
+
+const hexDigits = "0123456789abcdef"
+
+func printString(str []byte) string {
+ buf := make([]byte, 0, len(str))
+ for i := 0; i < len(str); i++ {
+ c := str[i]
+ if c == '.' || c == '-' || c == ' ' ||
+ 'A' <= c && c <= 'Z' ||
+ 'a' <= c && c <= 'z' ||
+ '0' <= c && c <= '9' {
+ buf = append(buf, c)
+ continue
+ }
+
+ upper := c >> 4
+ lower := (c << 4) >> 4
+ buf = append(
+ buf,
+ '\\',
+ 'x',
+ hexDigits[upper],
+ hexDigits[lower],
+ )
+ }
+ return string(buf)
+}
+
+func printUint16(i uint16) string {
+ return printUint32(uint32(i))
+}
+
+func printUint32(i uint32) string {
+ // Max value is 4294967295.
+ buf := make([]byte, 10)
+ for b, d := buf, uint32(1000000000); d > 0; d /= 10 {
+ b[0] = byte(i/d%10 + '0')
+ if b[0] == '0' && len(b) == len(buf) && len(buf) > 1 {
+ buf = buf[1:]
+ }
+ b = b[1:]
+ i %= d
+ }
+ return string(buf)
+}
+
+func printBool(b bool) string {
+ if b {
+ return "true"
+ }
+ return "false"
+}
+
+var (
+ // ErrNotStarted indicates that the prerequisite information isn't
+ // available yet because the previous records haven't been appropriately
+ // parsed, skipped or finished.
+ ErrNotStarted = errors.New("parsing/packing of this type isn't available yet")
+
+ // ErrSectionDone indicated that all records in the section have been
+ // parsed or finished.
+ ErrSectionDone = errors.New("parsing/packing of this section has completed")
+
+ errBaseLen = errors.New("insufficient data for base length type")
+ errCalcLen = errors.New("insufficient data for calculated length type")
+ errReserved = errors.New("segment prefix is reserved")
+ errTooManyPtr = errors.New("too many pointers (>10)")
+ errInvalidPtr = errors.New("invalid pointer")
+ errNilResouceBody = errors.New("nil resource body")
+ errResourceLen = errors.New("insufficient data for resource body length")
+ errSegTooLong = errors.New("segment length too long")
+ errZeroSegLen = errors.New("zero length segment")
+ errResTooLong = errors.New("resource length too long")
+ errTooManyQuestions = errors.New("too many Questions to pack (>65535)")
+ errTooManyAnswers = errors.New("too many Answers to pack (>65535)")
+ errTooManyAuthorities = errors.New("too many Authorities to pack (>65535)")
+ errTooManyAdditionals = errors.New("too many Additionals to pack (>65535)")
+ errNonCanonicalName = errors.New("name is not in canonical format (it must end with a .)")
+ errStringTooLong = errors.New("character string exceeds maximum length (255)")
+ errCompressedSRV = errors.New("compressed name in SRV resource data")
+)
+
+// Internal constants.
+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.
+ packStartingCap = 512
+
+ // uint16Len is the length (in bytes) of a uint16.
+ uint16Len = 2
+
+ // uint32Len is the length (in bytes) of a uint32.
+ uint32Len = 4
+
+ // headerLen is the length (in bytes) of a DNS header.
+ //
+ // A header is comprised of 6 uint16s and no padding.
+ headerLen = 6 * uint16Len
+)
+
+type nestedError struct {
+ // s is the current level's error message.
+ s string
+
+ // err is the nested error.
+ err error
+}
+
+// nestedError implements error.Error.
+func (e *nestedError) Error() string {
+ return e.s + ": " + e.err.Error()
+}
+
+// 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
+ RCode RCode
+}
+
+func (m *Header) pack() (id uint16, bits uint16) {
+ id = m.ID
+ bits = uint16(m.OpCode)<<11 | uint16(m.RCode)
+ if m.RecursionAvailable {
+ bits |= headerBitRA
+ }
+ if m.RecursionDesired {
+ bits |= headerBitRD
+ }
+ if m.Truncated {
+ bits |= headerBitTC
+ }
+ if m.Authoritative {
+ bits |= headerBitAA
+ }
+ if m.Response {
+ bits |= headerBitQR
+ }
+ return
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (m *Header) GoString() string {
+ return "dnsmessage.Header{" +
+ "ID: " + printUint16(m.ID) + ", " +
+ "Response: " + printBool(m.Response) + ", " +
+ "OpCode: " + m.OpCode.GoString() + ", " +
+ "Authoritative: " + printBool(m.Authoritative) + ", " +
+ "Truncated: " + printBool(m.Truncated) + ", " +
+ "RecursionDesired: " + printBool(m.RecursionDesired) + ", " +
+ "RecursionAvailable: " + printBool(m.RecursionAvailable) + ", " +
+ "RCode: " + m.RCode.GoString() + "}"
+}
+
+// Message is a representation of a DNS message.
+type Message struct {
+ Header
+ Questions []Question
+ Answers []Resource
+ Authorities []Resource
+ Additionals []Resource
+}
+
+type section uint8
+
+const (
+ sectionNotStarted section = iota
+ sectionHeader
+ sectionQuestions
+ sectionAnswers
+ sectionAuthorities
+ sectionAdditionals
+ sectionDone
+
+ headerBitQR = 1 << 15 // query/response (response=1)
+ headerBitAA = 1 << 10 // authoritative
+ headerBitTC = 1 << 9 // truncated
+ headerBitRD = 1 << 8 // recursion desired
+ headerBitRA = 1 << 7 // recursion available
+)
+
+var sectionNames = map[section]string{
+ sectionHeader: "header",
+ sectionQuestions: "Question",
+ sectionAnswers: "Answer",
+ sectionAuthorities: "Authority",
+ sectionAdditionals: "Additional",
+}
+
+// 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
+}
+
+func (h *header) count(sec section) uint16 {
+ switch sec {
+ case sectionQuestions:
+ return h.questions
+ case sectionAnswers:
+ return h.answers
+ case sectionAuthorities:
+ return h.authorities
+ case sectionAdditionals:
+ return h.additionals
+ }
+ return 0
+}
+
+// pack appends the wire format of the header to msg.
+func (h *header) pack(msg []byte) []byte {
+ msg = packUint16(msg, h.id)
+ msg = packUint16(msg, h.bits)
+ msg = packUint16(msg, h.questions)
+ msg = packUint16(msg, h.answers)
+ msg = packUint16(msg, h.authorities)
+ return packUint16(msg, h.additionals)
+}
+
+func (h *header) unpack(msg []byte, off int) (int, error) {
+ newOff := off
+ var err error
+ if h.id, newOff, err = unpackUint16(msg, newOff); err != nil {
+ return off, &nestedError{"id", err}
+ }
+ if h.bits, newOff, err = unpackUint16(msg, newOff); err != nil {
+ return off, &nestedError{"bits", err}
+ }
+ if h.questions, newOff, err = unpackUint16(msg, newOff); err != nil {
+ return off, &nestedError{"questions", err}
+ }
+ if h.answers, newOff, err = unpackUint16(msg, newOff); err != nil {
+ return off, &nestedError{"answers", err}
+ }
+ if h.authorities, newOff, err = unpackUint16(msg, newOff); err != nil {
+ return off, &nestedError{"authorities", err}
+ }
+ if h.additionals, newOff, err = unpackUint16(msg, newOff); err != nil {
+ return off, &nestedError{"additionals", err}
+ }
+ return newOff, nil
+}
+
+func (h *header) header() Header {
+ return Header{
+ ID: h.id,
+ Response: (h.bits & headerBitQR) != 0,
+ OpCode: OpCode(h.bits>>11) & 0xF,
+ Authoritative: (h.bits & headerBitAA) != 0,
+ Truncated: (h.bits & headerBitTC) != 0,
+ RecursionDesired: (h.bits & headerBitRD) != 0,
+ RecursionAvailable: (h.bits & headerBitRA) != 0,
+ RCode: RCode(h.bits & 0xF),
+ }
+}
+
+// A Resource is a DNS resource record.
+type Resource struct {
+ Header ResourceHeader
+ Body ResourceBody
+}
+
+func (r *Resource) GoString() string {
+ return "dnsmessage.Resource{" +
+ "Header: " + r.Header.GoString() +
+ ", Body: &" + r.Body.GoString() +
+ "}"
+}
+
+// A ResourceBody is a DNS resource record minus the header.
+type ResourceBody interface {
+ // pack packs a Resource except for its header.
+ pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error)
+
+ // realType returns the actual type of the Resource. This is used to
+ // fill in the header Type field.
+ realType() Type
+
+ // GoString implements fmt.GoStringer.GoString.
+ GoString() string
+}
+
+// pack appends the wire format of the Resource to msg.
+func (r *Resource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ if r.Body == nil {
+ return msg, errNilResouceBody
+ }
+ oldMsg := msg
+ r.Header.Type = r.Body.realType()
+ msg, lenOff, err := r.Header.pack(msg, compression, compressionOff)
+ if err != nil {
+ return msg, &nestedError{"ResourceHeader", err}
+ }
+ preLen := len(msg)
+ msg, err = r.Body.pack(msg, compression, compressionOff)
+ if err != nil {
+ return msg, &nestedError{"content", err}
+ }
+ if err := r.Header.fixLen(msg, lenOff, preLen); err != nil {
+ return oldMsg, err
+ }
+ return msg, nil
+}
+
+// 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 (nil, nil) and attempting to skip Questions will return
+// (true, nil). 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.
+//
+// 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
+ resHeader ResourceHeader
+}
+
+// Start parses the header and enables the parsing of Questions.
+func (p *Parser) Start(msg []byte) (Header, error) {
+ if p.msg != nil {
+ *p = Parser{}
+ }
+ p.msg = msg
+ var err error
+ if p.off, err = p.header.unpack(msg, 0); err != nil {
+ return Header{}, &nestedError{"unpacking header", err}
+ }
+ p.section = sectionQuestions
+ return p.header.header(), nil
+}
+
+func (p *Parser) checkAdvance(sec section) error {
+ if p.section < sec {
+ return ErrNotStarted
+ }
+ if p.section > sec {
+ return ErrSectionDone
+ }
+ p.resHeaderValid = false
+ if p.index == int(p.header.count(sec)) {
+ p.index = 0
+ p.section++
+ return ErrSectionDone
+ }
+ return nil
+}
+
+func (p *Parser) resource(sec section) (Resource, error) {
+ var r Resource
+ var err error
+ r.Header, err = p.resourceHeader(sec)
+ if err != nil {
+ return r, err
+ }
+ p.resHeaderValid = false
+ r.Body, p.off, err = unpackResourceBody(p.msg, p.off, r.Header)
+ if err != nil {
+ return Resource{}, &nestedError{"unpacking " + sectionNames[sec], err}
+ }
+ p.index++
+ return r, nil
+}
+
+func (p *Parser) resourceHeader(sec section) (ResourceHeader, error) {
+ if p.resHeaderValid {
+ return p.resHeader, nil
+ }
+ if err := p.checkAdvance(sec); err != nil {
+ return ResourceHeader{}, err
+ }
+ var hdr ResourceHeader
+ off, err := hdr.unpack(p.msg, p.off)
+ if err != nil {
+ return ResourceHeader{}, err
+ }
+ p.resHeaderValid = true
+ p.resHeader = hdr
+ p.off = off
+ return hdr, nil
+}
+
+func (p *Parser) skipResource(sec section) error {
+ if p.resHeaderValid {
+ newOff := p.off + int(p.resHeader.Length)
+ if newOff > len(p.msg) {
+ return errResourceLen
+ }
+ p.off = newOff
+ p.resHeaderValid = false
+ p.index++
+ return nil
+ }
+ if err := p.checkAdvance(sec); err != nil {
+ return err
+ }
+ var err error
+ p.off, err = skipResource(p.msg, p.off)
+ if err != nil {
+ return &nestedError{"skipping: " + sectionNames[sec], err}
+ }
+ p.index++
+ return nil
+}
+
+// Question parses a single Question.
+func (p *Parser) Question() (Question, error) {
+ if err := p.checkAdvance(sectionQuestions); err != nil {
+ return Question{}, err
+ }
+ var name Name
+ off, err := name.unpack(p.msg, p.off)
+ if err != nil {
+ return Question{}, &nestedError{"unpacking Question.Name", err}
+ }
+ typ, off, err := unpackType(p.msg, off)
+ if err != nil {
+ return Question{}, &nestedError{"unpacking Question.Type", err}
+ }
+ class, off, err := unpackClass(p.msg, off)
+ if err != nil {
+ return Question{}, &nestedError{"unpacking Question.Class", err}
+ }
+ p.off = off
+ p.index++
+ return Question{name, typ, class}, nil
+}
+
+// AllQuestions parses all Questions.
+func (p *Parser) AllQuestions() ([]Question, error) {
+ // Multiple questions are valid according to the spec,
+ // but servers don't actually support them. There will
+ // be at most one question here.
+ //
+ // Do not pre-allocate based on info in p.header, since
+ // the data is untrusted.
+ qs := []Question{}
+ for {
+ q, err := p.Question()
+ if err == ErrSectionDone {
+ return qs, nil
+ }
+ if err != nil {
+ return nil, err
+ }
+ qs = append(qs, q)
+ }
+}
+
+// SkipQuestion skips a single Question.
+func (p *Parser) SkipQuestion() error {
+ if err := p.checkAdvance(sectionQuestions); err != nil {
+ return err
+ }
+ off, err := skipName(p.msg, p.off)
+ if err != nil {
+ return &nestedError{"skipping Question Name", err}
+ }
+ if off, err = skipType(p.msg, off); err != nil {
+ return &nestedError{"skipping Question Type", err}
+ }
+ if off, err = skipClass(p.msg, off); err != nil {
+ return &nestedError{"skipping Question Class", err}
+ }
+ p.off = off
+ p.index++
+ return nil
+}
+
+// SkipAllQuestions skips all Questions.
+func (p *Parser) SkipAllQuestions() error {
+ for {
+ if err := p.SkipQuestion(); err == ErrSectionDone {
+ return nil
+ } else if err != nil {
+ return err
+ }
+ }
+}
+
+// AnswerHeader parses a single Answer ResourceHeader.
+func (p *Parser) AnswerHeader() (ResourceHeader, error) {
+ return p.resourceHeader(sectionAnswers)
+}
+
+// Answer parses a single Answer Resource.
+func (p *Parser) Answer() (Resource, error) {
+ return p.resource(sectionAnswers)
+}
+
+// AllAnswers parses all Answer Resources.
+func (p *Parser) AllAnswers() ([]Resource, error) {
+ // The most common query is for A/AAAA, which usually returns
+ // a handful of IPs.
+ //
+ // Pre-allocate up to a certain limit, since p.header is
+ // untrusted data.
+ n := int(p.header.answers)
+ if n > 20 {
+ n = 20
+ }
+ as := make([]Resource, 0, n)
+ for {
+ a, err := p.Answer()
+ if err == ErrSectionDone {
+ return as, nil
+ }
+ if err != nil {
+ return nil, err
+ }
+ as = append(as, a)
+ }
+}
+
+// SkipAnswer skips a single Answer Resource.
+func (p *Parser) SkipAnswer() error {
+ return p.skipResource(sectionAnswers)
+}
+
+// SkipAllAnswers skips all Answer Resources.
+func (p *Parser) SkipAllAnswers() error {
+ for {
+ if err := p.SkipAnswer(); err == ErrSectionDone {
+ return nil
+ } else if err != nil {
+ return err
+ }
+ }
+}
+
+// AuthorityHeader parses a single Authority ResourceHeader.
+func (p *Parser) AuthorityHeader() (ResourceHeader, error) {
+ return p.resourceHeader(sectionAuthorities)
+}
+
+// Authority parses a single Authority Resource.
+func (p *Parser) Authority() (Resource, error) {
+ return p.resource(sectionAuthorities)
+}
+
+// AllAuthorities parses all Authority Resources.
+func (p *Parser) AllAuthorities() ([]Resource, error) {
+ // Authorities contains SOA in case of NXDOMAIN and friends,
+ // otherwise it is empty.
+ //
+ // Pre-allocate up to a certain limit, since p.header is
+ // untrusted data.
+ n := int(p.header.authorities)
+ if n > 10 {
+ n = 10
+ }
+ as := make([]Resource, 0, n)
+ for {
+ a, err := p.Authority()
+ if err == ErrSectionDone {
+ return as, nil
+ }
+ if err != nil {
+ return nil, err
+ }
+ as = append(as, a)
+ }
+}
+
+// SkipAuthority skips a single Authority Resource.
+func (p *Parser) SkipAuthority() error {
+ return p.skipResource(sectionAuthorities)
+}
+
+// SkipAllAuthorities skips all Authority Resources.
+func (p *Parser) SkipAllAuthorities() error {
+ for {
+ if err := p.SkipAuthority(); err == ErrSectionDone {
+ return nil
+ } else if err != nil {
+ return err
+ }
+ }
+}
+
+// AdditionalHeader parses a single Additional ResourceHeader.
+func (p *Parser) AdditionalHeader() (ResourceHeader, error) {
+ return p.resourceHeader(sectionAdditionals)
+}
+
+// Additional parses a single Additional Resource.
+func (p *Parser) Additional() (Resource, error) {
+ return p.resource(sectionAdditionals)
+}
+
+// AllAdditionals parses all Additional Resources.
+func (p *Parser) AllAdditionals() ([]Resource, error) {
+ // Additionals usually contain OPT, and sometimes A/AAAA
+ // glue records.
+ //
+ // Pre-allocate up to a certain limit, since p.header is
+ // untrusted data.
+ n := int(p.header.additionals)
+ if n > 10 {
+ n = 10
+ }
+ as := make([]Resource, 0, n)
+ for {
+ a, err := p.Additional()
+ if err == ErrSectionDone {
+ return as, nil
+ }
+ if err != nil {
+ return nil, err
+ }
+ as = append(as, a)
+ }
+}
+
+// SkipAdditional skips a single Additional Resource.
+func (p *Parser) SkipAdditional() error {
+ return p.skipResource(sectionAdditionals)
+}
+
+// SkipAllAdditionals skips all Additional Resources.
+func (p *Parser) SkipAllAdditionals() error {
+ for {
+ if err := p.SkipAdditional(); err == ErrSectionDone {
+ return nil
+ } else if err != nil {
+ return err
+ }
+ }
+}
+
+// CNAMEResource parses a single CNAMEResource.
+//
+// One of the XXXHeader methods must have been called before calling this
+// method.
+func (p *Parser) CNAMEResource() (CNAMEResource, error) {
+ if !p.resHeaderValid || p.resHeader.Type != TypeCNAME {
+ return CNAMEResource{}, ErrNotStarted
+ }
+ r, err := unpackCNAMEResource(p.msg, p.off)
+ if err != nil {
+ return CNAMEResource{}, err
+ }
+ p.off += int(p.resHeader.Length)
+ p.resHeaderValid = false
+ p.index++
+ return r, nil
+}
+
+// MXResource parses a single MXResource.
+//
+// One of the XXXHeader methods must have been called before calling this
+// method.
+func (p *Parser) MXResource() (MXResource, error) {
+ if !p.resHeaderValid || p.resHeader.Type != TypeMX {
+ return MXResource{}, ErrNotStarted
+ }
+ r, err := unpackMXResource(p.msg, p.off)
+ if err != nil {
+ return MXResource{}, err
+ }
+ p.off += int(p.resHeader.Length)
+ p.resHeaderValid = false
+ p.index++
+ return r, nil
+}
+
+// NSResource parses a single NSResource.
+//
+// One of the XXXHeader methods must have been called before calling this
+// method.
+func (p *Parser) NSResource() (NSResource, error) {
+ if !p.resHeaderValid || p.resHeader.Type != TypeNS {
+ return NSResource{}, ErrNotStarted
+ }
+ r, err := unpackNSResource(p.msg, p.off)
+ if err != nil {
+ return NSResource{}, err
+ }
+ p.off += int(p.resHeader.Length)
+ p.resHeaderValid = false
+ p.index++
+ return r, nil
+}
+
+// PTRResource parses a single PTRResource.
+//
+// One of the XXXHeader methods must have been called before calling this
+// method.
+func (p *Parser) PTRResource() (PTRResource, error) {
+ if !p.resHeaderValid || p.resHeader.Type != TypePTR {
+ return PTRResource{}, ErrNotStarted
+ }
+ r, err := unpackPTRResource(p.msg, p.off)
+ if err != nil {
+ return PTRResource{}, err
+ }
+ p.off += int(p.resHeader.Length)
+ p.resHeaderValid = false
+ p.index++
+ return r, nil
+}
+
+// SOAResource parses a single SOAResource.
+//
+// One of the XXXHeader methods must have been called before calling this
+// method.
+func (p *Parser) SOAResource() (SOAResource, error) {
+ if !p.resHeaderValid || p.resHeader.Type != TypeSOA {
+ return SOAResource{}, ErrNotStarted
+ }
+ r, err := unpackSOAResource(p.msg, p.off)
+ if err != nil {
+ return SOAResource{}, err
+ }
+ p.off += int(p.resHeader.Length)
+ p.resHeaderValid = false
+ p.index++
+ return r, nil
+}
+
+// TXTResource parses a single TXTResource.
+//
+// One of the XXXHeader methods must have been called before calling this
+// method.
+func (p *Parser) TXTResource() (TXTResource, error) {
+ if !p.resHeaderValid || p.resHeader.Type != TypeTXT {
+ return TXTResource{}, ErrNotStarted
+ }
+ r, err := unpackTXTResource(p.msg, p.off, p.resHeader.Length)
+ if err != nil {
+ return TXTResource{}, err
+ }
+ p.off += int(p.resHeader.Length)
+ p.resHeaderValid = false
+ p.index++
+ return r, nil
+}
+
+// SRVResource parses a single SRVResource.
+//
+// One of the XXXHeader methods must have been called before calling this
+// method.
+func (p *Parser) SRVResource() (SRVResource, error) {
+ if !p.resHeaderValid || p.resHeader.Type != TypeSRV {
+ return SRVResource{}, ErrNotStarted
+ }
+ r, err := unpackSRVResource(p.msg, p.off)
+ if err != nil {
+ return SRVResource{}, err
+ }
+ p.off += int(p.resHeader.Length)
+ p.resHeaderValid = false
+ p.index++
+ return r, nil
+}
+
+// AResource parses a single AResource.
+//
+// One of the XXXHeader methods must have been called before calling this
+// method.
+func (p *Parser) AResource() (AResource, error) {
+ if !p.resHeaderValid || p.resHeader.Type != TypeA {
+ return AResource{}, ErrNotStarted
+ }
+ r, err := unpackAResource(p.msg, p.off)
+ if err != nil {
+ return AResource{}, err
+ }
+ p.off += int(p.resHeader.Length)
+ p.resHeaderValid = false
+ p.index++
+ return r, nil
+}
+
+// AAAAResource parses a single AAAAResource.
+//
+// One of the XXXHeader methods must have been called before calling this
+// method.
+func (p *Parser) AAAAResource() (AAAAResource, error) {
+ if !p.resHeaderValid || p.resHeader.Type != TypeAAAA {
+ return AAAAResource{}, ErrNotStarted
+ }
+ r, err := unpackAAAAResource(p.msg, p.off)
+ if err != nil {
+ return AAAAResource{}, err
+ }
+ p.off += int(p.resHeader.Length)
+ p.resHeaderValid = false
+ p.index++
+ return r, nil
+}
+
+// OPTResource parses a single OPTResource.
+//
+// One of the XXXHeader methods must have been called before calling this
+// method.
+func (p *Parser) OPTResource() (OPTResource, error) {
+ if !p.resHeaderValid || p.resHeader.Type != TypeOPT {
+ return OPTResource{}, ErrNotStarted
+ }
+ r, err := unpackOPTResource(p.msg, p.off, p.resHeader.Length)
+ if err != nil {
+ return OPTResource{}, err
+ }
+ p.off += int(p.resHeader.Length)
+ p.resHeaderValid = false
+ p.index++
+ return r, nil
+}
+
+// Unpack parses a full Message.
+func (m *Message) Unpack(msg []byte) error {
+ var p Parser
+ var err error
+ if m.Header, err = p.Start(msg); err != nil {
+ return err
+ }
+ if m.Questions, err = p.AllQuestions(); err != nil {
+ return err
+ }
+ if m.Answers, err = p.AllAnswers(); err != nil {
+ return err
+ }
+ if m.Authorities, err = p.AllAuthorities(); err != nil {
+ return err
+ }
+ if m.Additionals, err = p.AllAdditionals(); err != nil {
+ return err
+ }
+ return nil
+}
+
+// Pack packs a full Message.
+func (m *Message) Pack() ([]byte, error) {
+ return m.AppendPack(make([]byte, 0, packStartingCap))
+}
+
+// AppendPack is like Pack but appends the full Message to b and returns the
+// extended buffer.
+func (m *Message) AppendPack(b []byte) ([]byte, error) {
+ // Validate the lengths. It is very unlikely that anyone will try to
+ // pack more than 65535 of any particular type, but it is possible and
+ // we should fail gracefully.
+ if len(m.Questions) > int(^uint16(0)) {
+ return nil, errTooManyQuestions
+ }
+ if len(m.Answers) > int(^uint16(0)) {
+ return nil, errTooManyAnswers
+ }
+ if len(m.Authorities) > int(^uint16(0)) {
+ return nil, errTooManyAuthorities
+ }
+ if len(m.Additionals) > int(^uint16(0)) {
+ return nil, errTooManyAdditionals
+ }
+
+ var h header
+ h.id, h.bits = m.Header.pack()
+
+ h.questions = uint16(len(m.Questions))
+ h.answers = uint16(len(m.Answers))
+ h.authorities = uint16(len(m.Authorities))
+ h.additionals = uint16(len(m.Additionals))
+
+ compressionOff := len(b)
+ msg := h.pack(b)
+
+ // RFC 1035 allows (but does not require) compression for packing. RFC
+ // 1035 requires unpacking implementations to support compression, so
+ // unconditionally enabling it is fine.
+ //
+ // DNS lookups are typically done over UDP, and RFC 1035 states that UDP
+ // DNS messages can be a maximum of 512 bytes long. Without compression,
+ // many DNS response messages are over this limit, so enabling
+ // compression will help ensure compliance.
+ compression := map[string]int{}
+
+ for i := range m.Questions {
+ var err error
+ if msg, err = m.Questions[i].pack(msg, compression, compressionOff); err != nil {
+ return nil, &nestedError{"packing Question", err}
+ }
+ }
+ for i := range m.Answers {
+ var err error
+ if msg, err = m.Answers[i].pack(msg, compression, compressionOff); err != nil {
+ return nil, &nestedError{"packing Answer", err}
+ }
+ }
+ for i := range m.Authorities {
+ var err error
+ if msg, err = m.Authorities[i].pack(msg, compression, compressionOff); err != nil {
+ return nil, &nestedError{"packing Authority", err}
+ }
+ }
+ for i := range m.Additionals {
+ var err error
+ if msg, err = m.Additionals[i].pack(msg, compression, compressionOff); err != nil {
+ return nil, &nestedError{"packing Additional", err}
+ }
+ }
+
+ return msg, nil
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (m *Message) GoString() string {
+ s := "dnsmessage.Message{Header: " + m.Header.GoString() + ", " +
+ "Questions: []dnsmessage.Question{"
+ if len(m.Questions) > 0 {
+ s += m.Questions[0].GoString()
+ for _, q := range m.Questions[1:] {
+ s += ", " + q.GoString()
+ }
+ }
+ s += "}, Answers: []dnsmessage.Resource{"
+ if len(m.Answers) > 0 {
+ s += m.Answers[0].GoString()
+ for _, a := range m.Answers[1:] {
+ s += ", " + a.GoString()
+ }
+ }
+ s += "}, Authorities: []dnsmessage.Resource{"
+ if len(m.Authorities) > 0 {
+ s += m.Authorities[0].GoString()
+ for _, a := range m.Authorities[1:] {
+ s += ", " + a.GoString()
+ }
+ }
+ s += "}, Additionals: []dnsmessage.Resource{"
+ if len(m.Additionals) > 0 {
+ s += m.Additionals[0].GoString()
+ for _, a := range m.Additionals[1:] {
+ s += ", " + a.GoString()
+ }
+ }
+ return s + "}}"
+}
+
+// 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 is the storage for the message being built.
+ msg []byte
+
+ // section keeps track of the current section being built.
+ section section
+
+ // header keeps track of what should go in the header when Finish is
+ // called.
+ header header
+
+ // start is the starting index of the bytes allocated in msg for header.
+ start int
+
+ // compression is a mapping from name suffixes to their starting index
+ // in msg.
+ compression map[string]int
+}
+
+// NewBuilder creates a new builder with compression disabled.
+//
+// Note: Most users will want to immediately enable compression with the
+// EnableCompression method. See that method's comment for why you may or may
+// not want to enable compression.
+//
+// The DNS message is appended to the provided initial buffer buf (which may be
+// nil) as it is built. The final message is returned by the (*Builder).Finish
+// method, which may return the same underlying array if there was sufficient
+// capacity in the slice.
+func NewBuilder(buf []byte, h Header) Builder {
+ if buf == nil {
+ buf = make([]byte, 0, packStartingCap)
+ }
+ b := Builder{msg: buf, start: len(buf)}
+ b.header.id, b.header.bits = h.pack()
+ var hb [headerLen]byte
+ b.msg = append(b.msg, hb[:]...)
+ b.section = sectionHeader
+ return b
+}
+
+// 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() {
+ b.compression = map[string]int{}
+}
+
+func (b *Builder) startCheck(s section) error {
+ if b.section <= sectionNotStarted {
+ return ErrNotStarted
+ }
+ if b.section > s {
+ return ErrSectionDone
+ }
+ return nil
+}
+
+// StartQuestions prepares the builder for packing Questions.
+func (b *Builder) StartQuestions() error {
+ if err := b.startCheck(sectionQuestions); err != nil {
+ return err
+ }
+ b.section = sectionQuestions
+ return nil
+}
+
+// StartAnswers prepares the builder for packing Answers.
+func (b *Builder) StartAnswers() error {
+ if err := b.startCheck(sectionAnswers); err != nil {
+ return err
+ }
+ b.section = sectionAnswers
+ return nil
+}
+
+// StartAuthorities prepares the builder for packing Authorities.
+func (b *Builder) StartAuthorities() error {
+ if err := b.startCheck(sectionAuthorities); err != nil {
+ return err
+ }
+ b.section = sectionAuthorities
+ return nil
+}
+
+// StartAdditionals prepares the builder for packing Additionals.
+func (b *Builder) StartAdditionals() error {
+ if err := b.startCheck(sectionAdditionals); err != nil {
+ return err
+ }
+ b.section = sectionAdditionals
+ return nil
+}
+
+func (b *Builder) incrementSectionCount() error {
+ var count *uint16
+ var err error
+ switch b.section {
+ case sectionQuestions:
+ count = &b.header.questions
+ err = errTooManyQuestions
+ case sectionAnswers:
+ count = &b.header.answers
+ err = errTooManyAnswers
+ case sectionAuthorities:
+ count = &b.header.authorities
+ err = errTooManyAuthorities
+ case sectionAdditionals:
+ count = &b.header.additionals
+ err = errTooManyAdditionals
+ }
+ if *count == ^uint16(0) {
+ return err
+ }
+ *count++
+ return nil
+}
+
+// Question adds a single Question.
+func (b *Builder) Question(q Question) error {
+ if b.section < sectionQuestions {
+ return ErrNotStarted
+ }
+ if b.section > sectionQuestions {
+ return ErrSectionDone
+ }
+ msg, err := q.pack(b.msg, b.compression, b.start)
+ if err != nil {
+ return err
+ }
+ if err := b.incrementSectionCount(); err != nil {
+ return err
+ }
+ b.msg = msg
+ return nil
+}
+
+func (b *Builder) checkResourceSection() error {
+ if b.section < sectionAnswers {
+ return ErrNotStarted
+ }
+ if b.section > sectionAdditionals {
+ return ErrSectionDone
+ }
+ return nil
+}
+
+// CNAMEResource adds a single CNAMEResource.
+func (b *Builder) CNAMEResource(h ResourceHeader, r CNAMEResource) error {
+ if err := b.checkResourceSection(); err != nil {
+ return err
+ }
+ h.Type = r.realType()
+ msg, lenOff, err := h.pack(b.msg, b.compression, b.start)
+ if err != nil {
+ return &nestedError{"ResourceHeader", err}
+ }
+ preLen := len(msg)
+ if msg, err = r.pack(msg, b.compression, b.start); err != nil {
+ return &nestedError{"CNAMEResource body", err}
+ }
+ if err := h.fixLen(msg, lenOff, preLen); err != nil {
+ return err
+ }
+ if err := b.incrementSectionCount(); err != nil {
+ return err
+ }
+ b.msg = msg
+ return nil
+}
+
+// MXResource adds a single MXResource.
+func (b *Builder) MXResource(h ResourceHeader, r MXResource) error {
+ if err := b.checkResourceSection(); err != nil {
+ return err
+ }
+ h.Type = r.realType()
+ msg, lenOff, err := h.pack(b.msg, b.compression, b.start)
+ if err != nil {
+ return &nestedError{"ResourceHeader", err}
+ }
+ preLen := len(msg)
+ if msg, err = r.pack(msg, b.compression, b.start); err != nil {
+ return &nestedError{"MXResource body", err}
+ }
+ if err := h.fixLen(msg, lenOff, preLen); err != nil {
+ return err
+ }
+ if err := b.incrementSectionCount(); err != nil {
+ return err
+ }
+ b.msg = msg
+ return nil
+}
+
+// NSResource adds a single NSResource.
+func (b *Builder) NSResource(h ResourceHeader, r NSResource) error {
+ if err := b.checkResourceSection(); err != nil {
+ return err
+ }
+ h.Type = r.realType()
+ msg, lenOff, err := h.pack(b.msg, b.compression, b.start)
+ if err != nil {
+ return &nestedError{"ResourceHeader", err}
+ }
+ preLen := len(msg)
+ if msg, err = r.pack(msg, b.compression, b.start); err != nil {
+ return &nestedError{"NSResource body", err}
+ }
+ if err := h.fixLen(msg, lenOff, preLen); err != nil {
+ return err
+ }
+ if err := b.incrementSectionCount(); err != nil {
+ return err
+ }
+ b.msg = msg
+ return nil
+}
+
+// PTRResource adds a single PTRResource.
+func (b *Builder) PTRResource(h ResourceHeader, r PTRResource) error {
+ if err := b.checkResourceSection(); err != nil {
+ return err
+ }
+ h.Type = r.realType()
+ msg, lenOff, err := h.pack(b.msg, b.compression, b.start)
+ if err != nil {
+ return &nestedError{"ResourceHeader", err}
+ }
+ preLen := len(msg)
+ if msg, err = r.pack(msg, b.compression, b.start); err != nil {
+ return &nestedError{"PTRResource body", err}
+ }
+ if err := h.fixLen(msg, lenOff, preLen); err != nil {
+ return err
+ }
+ if err := b.incrementSectionCount(); err != nil {
+ return err
+ }
+ b.msg = msg
+ return nil
+}
+
+// SOAResource adds a single SOAResource.
+func (b *Builder) SOAResource(h ResourceHeader, r SOAResource) error {
+ if err := b.checkResourceSection(); err != nil {
+ return err
+ }
+ h.Type = r.realType()
+ msg, lenOff, err := h.pack(b.msg, b.compression, b.start)
+ if err != nil {
+ return &nestedError{"ResourceHeader", err}
+ }
+ preLen := len(msg)
+ if msg, err = r.pack(msg, b.compression, b.start); err != nil {
+ return &nestedError{"SOAResource body", err}
+ }
+ if err := h.fixLen(msg, lenOff, preLen); err != nil {
+ return err
+ }
+ if err := b.incrementSectionCount(); err != nil {
+ return err
+ }
+ b.msg = msg
+ return nil
+}
+
+// TXTResource adds a single TXTResource.
+func (b *Builder) TXTResource(h ResourceHeader, r TXTResource) error {
+ if err := b.checkResourceSection(); err != nil {
+ return err
+ }
+ h.Type = r.realType()
+ msg, lenOff, err := h.pack(b.msg, b.compression, b.start)
+ if err != nil {
+ return &nestedError{"ResourceHeader", err}
+ }
+ preLen := len(msg)
+ if msg, err = r.pack(msg, b.compression, b.start); err != nil {
+ return &nestedError{"TXTResource body", err}
+ }
+ if err := h.fixLen(msg, lenOff, preLen); err != nil {
+ return err
+ }
+ if err := b.incrementSectionCount(); err != nil {
+ return err
+ }
+ b.msg = msg
+ return nil
+}
+
+// SRVResource adds a single SRVResource.
+func (b *Builder) SRVResource(h ResourceHeader, r SRVResource) error {
+ if err := b.checkResourceSection(); err != nil {
+ return err
+ }
+ h.Type = r.realType()
+ msg, lenOff, err := h.pack(b.msg, b.compression, b.start)
+ if err != nil {
+ return &nestedError{"ResourceHeader", err}
+ }
+ preLen := len(msg)
+ if msg, err = r.pack(msg, b.compression, b.start); err != nil {
+ return &nestedError{"SRVResource body", err}
+ }
+ if err := h.fixLen(msg, lenOff, preLen); err != nil {
+ return err
+ }
+ if err := b.incrementSectionCount(); err != nil {
+ return err
+ }
+ b.msg = msg
+ return nil
+}
+
+// AResource adds a single AResource.
+func (b *Builder) AResource(h ResourceHeader, r AResource) error {
+ if err := b.checkResourceSection(); err != nil {
+ return err
+ }
+ h.Type = r.realType()
+ msg, lenOff, err := h.pack(b.msg, b.compression, b.start)
+ if err != nil {
+ return &nestedError{"ResourceHeader", err}
+ }
+ preLen := len(msg)
+ if msg, err = r.pack(msg, b.compression, b.start); err != nil {
+ return &nestedError{"AResource body", err}
+ }
+ if err := h.fixLen(msg, lenOff, preLen); err != nil {
+ return err
+ }
+ if err := b.incrementSectionCount(); err != nil {
+ return err
+ }
+ b.msg = msg
+ return nil
+}
+
+// AAAAResource adds a single AAAAResource.
+func (b *Builder) AAAAResource(h ResourceHeader, r AAAAResource) error {
+ if err := b.checkResourceSection(); err != nil {
+ return err
+ }
+ h.Type = r.realType()
+ msg, lenOff, err := h.pack(b.msg, b.compression, b.start)
+ if err != nil {
+ return &nestedError{"ResourceHeader", err}
+ }
+ preLen := len(msg)
+ if msg, err = r.pack(msg, b.compression, b.start); err != nil {
+ return &nestedError{"AAAAResource body", err}
+ }
+ if err := h.fixLen(msg, lenOff, preLen); err != nil {
+ return err
+ }
+ if err := b.incrementSectionCount(); err != nil {
+ return err
+ }
+ b.msg = msg
+ return nil
+}
+
+// OPTResource adds a single OPTResource.
+func (b *Builder) OPTResource(h ResourceHeader, r OPTResource) error {
+ if err := b.checkResourceSection(); err != nil {
+ return err
+ }
+ h.Type = r.realType()
+ msg, lenOff, err := h.pack(b.msg, b.compression, b.start)
+ if err != nil {
+ return &nestedError{"ResourceHeader", err}
+ }
+ preLen := len(msg)
+ if msg, err = r.pack(msg, b.compression, b.start); err != nil {
+ return &nestedError{"OPTResource body", err}
+ }
+ if err := h.fixLen(msg, lenOff, preLen); err != nil {
+ return err
+ }
+ if err := b.incrementSectionCount(); err != nil {
+ return err
+ }
+ b.msg = msg
+ return nil
+}
+
+// Finish ends message building and generates a binary message.
+func (b *Builder) Finish() ([]byte, error) {
+ if b.section < sectionHeader {
+ return nil, ErrNotStarted
+ }
+ b.section = sectionDone
+ // Space for the header was allocated in NewBuilder.
+ b.header.pack(b.msg[b.start:b.start])
+ return b.msg, nil
+}
+
+// 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 is the domain name for which this resource record pertains.
+ Name Name
+
+ // Type is the type of DNS resource record.
+ //
+ // This field will be set automatically during packing.
+ Type Type
+
+ // Class is the class of network to which this DNS resource record
+ // pertains.
+ Class Class
+
+ // TTL is the length of time (measured in seconds) which this resource
+ // record is valid for (time to live). All Resources in a set should
+ // have the same TTL (RFC 2181 Section 5.2).
+ TTL uint32
+
+ // Length is the length of data in the resource record after the header.
+ //
+ // This field will be set automatically during packing.
+ Length uint16
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (h *ResourceHeader) GoString() string {
+ return "dnsmessage.ResourceHeader{" +
+ "Name: " + h.Name.GoString() + ", " +
+ "Type: " + h.Type.GoString() + ", " +
+ "Class: " + h.Class.GoString() + ", " +
+ "TTL: " + printUint32(h.TTL) + ", " +
+ "Length: " + printUint16(h.Length) + "}"
+}
+
+// pack appends the wire format of the ResourceHeader to oldMsg.
+//
+// lenOff is the offset in msg where the Length field was packed.
+func (h *ResourceHeader) pack(oldMsg []byte, compression map[string]int, compressionOff int) (msg []byte, lenOff int, err error) {
+ msg = oldMsg
+ if msg, err = h.Name.pack(msg, compression, compressionOff); err != nil {
+ return oldMsg, 0, &nestedError{"Name", err}
+ }
+ msg = packType(msg, h.Type)
+ msg = packClass(msg, h.Class)
+ msg = packUint32(msg, h.TTL)
+ lenOff = len(msg)
+ msg = packUint16(msg, h.Length)
+ return msg, lenOff, nil
+}
+
+func (h *ResourceHeader) unpack(msg []byte, off int) (int, error) {
+ newOff := off
+ var err error
+ if newOff, err = h.Name.unpack(msg, newOff); err != nil {
+ return off, &nestedError{"Name", err}
+ }
+ if h.Type, newOff, err = unpackType(msg, newOff); err != nil {
+ return off, &nestedError{"Type", err}
+ }
+ if h.Class, newOff, err = unpackClass(msg, newOff); err != nil {
+ return off, &nestedError{"Class", err}
+ }
+ if h.TTL, newOff, err = unpackUint32(msg, newOff); err != nil {
+ return off, &nestedError{"TTL", err}
+ }
+ if h.Length, newOff, err = unpackUint16(msg, newOff); err != nil {
+ return off, &nestedError{"Length", err}
+ }
+ return newOff, nil
+}
+
+// fixLen updates a packed ResourceHeader to include the length of the
+// ResourceBody.
+//
+// lenOff is the offset of the ResourceHeader.Length field in msg.
+//
+// preLen is the length that msg was before the ResourceBody was packed.
+func (h *ResourceHeader) fixLen(msg []byte, lenOff int, preLen int) error {
+ conLen := len(msg) - preLen
+ if conLen > int(^uint16(0)) {
+ return errResTooLong
+ }
+
+ // Fill in the length now that we know how long the content is.
+ packUint16(msg[lenOff:lenOff], uint16(conLen))
+ h.Length = uint16(conLen)
+
+ return nil
+}
+
+// EDNS(0) wire costants.
+const (
+ edns0Version = 0
+
+ edns0DNSSECOK = 0x00008000
+ ednsVersionMask = 0x00ff0000
+ edns0DNSSECOKMask = 0x00ff8000
+)
+
+// SetEDNS0 configures h for EDNS(0).
+//
+// The provided extRCode must be an extedned RCode.
+func (h *ResourceHeader) SetEDNS0(udpPayloadLen int, extRCode RCode, dnssecOK bool) error {
+ h.Name = Name{Data: [nameLen]byte{'.'}, Length: 1} // RFC 6891 section 6.1.2
+ h.Type = TypeOPT
+ h.Class = Class(udpPayloadLen)
+ h.TTL = uint32(extRCode) >> 4 << 24
+ if dnssecOK {
+ h.TTL |= edns0DNSSECOK
+ }
+ return nil
+}
+
+// DNSSECAllowed reports whether the DNSSEC OK bit is set.
+func (h *ResourceHeader) DNSSECAllowed() bool {
+ return h.TTL&edns0DNSSECOKMask == edns0DNSSECOK // RFC 6891 section 6.1.3
+}
+
+// ExtendedRCode returns an extended RCode.
+//
+// The provided rcode must be the RCode in DNS message header.
+func (h *ResourceHeader) ExtendedRCode(rcode RCode) RCode {
+ if h.TTL&ednsVersionMask == edns0Version { // RFC 6891 section 6.1.3
+ return RCode(h.TTL>>24<<4) | rcode
+ }
+ return rcode
+}
+
+func skipResource(msg []byte, off int) (int, error) {
+ newOff, err := skipName(msg, off)
+ if err != nil {
+ return off, &nestedError{"Name", err}
+ }
+ if newOff, err = skipType(msg, newOff); err != nil {
+ return off, &nestedError{"Type", err}
+ }
+ if newOff, err = skipClass(msg, newOff); err != nil {
+ return off, &nestedError{"Class", err}
+ }
+ if newOff, err = skipUint32(msg, newOff); err != nil {
+ return off, &nestedError{"TTL", err}
+ }
+ length, newOff, err := unpackUint16(msg, newOff)
+ if err != nil {
+ return off, &nestedError{"Length", err}
+ }
+ if newOff += int(length); newOff > len(msg) {
+ return off, errResourceLen
+ }
+ return newOff, nil
+}
+
+// packUint16 appends the wire format of field to msg.
+func packUint16(msg []byte, field uint16) []byte {
+ return append(msg, byte(field>>8), byte(field))
+}
+
+func unpackUint16(msg []byte, off int) (uint16, int, error) {
+ if off+uint16Len > len(msg) {
+ return 0, off, errBaseLen
+ }
+ return uint16(msg[off])<<8 | uint16(msg[off+1]), off + uint16Len, nil
+}
+
+func skipUint16(msg []byte, off int) (int, error) {
+ if off+uint16Len > len(msg) {
+ return off, errBaseLen
+ }
+ return off + uint16Len, nil
+}
+
+// packType appends the wire format of field to msg.
+func packType(msg []byte, field Type) []byte {
+ return packUint16(msg, uint16(field))
+}
+
+func unpackType(msg []byte, off int) (Type, int, error) {
+ t, o, err := unpackUint16(msg, off)
+ return Type(t), o, err
+}
+
+func skipType(msg []byte, off int) (int, error) {
+ return skipUint16(msg, off)
+}
+
+// packClass appends the wire format of field to msg.
+func packClass(msg []byte, field Class) []byte {
+ return packUint16(msg, uint16(field))
+}
+
+func unpackClass(msg []byte, off int) (Class, int, error) {
+ c, o, err := unpackUint16(msg, off)
+ return Class(c), o, err
+}
+
+func skipClass(msg []byte, off int) (int, error) {
+ return skipUint16(msg, off)
+}
+
+// packUint32 appends the wire format of field to msg.
+func packUint32(msg []byte, field uint32) []byte {
+ return append(
+ msg,
+ byte(field>>24),
+ byte(field>>16),
+ byte(field>>8),
+ byte(field),
+ )
+}
+
+func unpackUint32(msg []byte, off int) (uint32, int, error) {
+ if off+uint32Len > len(msg) {
+ return 0, off, errBaseLen
+ }
+ v := uint32(msg[off])<<24 | uint32(msg[off+1])<<16 | uint32(msg[off+2])<<8 | uint32(msg[off+3])
+ return v, off + uint32Len, nil
+}
+
+func skipUint32(msg []byte, off int) (int, error) {
+ if off+uint32Len > len(msg) {
+ return off, errBaseLen
+ }
+ return off + uint32Len, nil
+}
+
+// packText appends the wire format of field to msg.
+func packText(msg []byte, field string) ([]byte, error) {
+ l := len(field)
+ if l > 255 {
+ return nil, errStringTooLong
+ }
+ msg = append(msg, byte(l))
+ msg = append(msg, field...)
+
+ return msg, nil
+}
+
+func unpackText(msg []byte, off int) (string, int, error) {
+ if off >= len(msg) {
+ return "", off, errBaseLen
+ }
+ beginOff := off + 1
+ endOff := beginOff + int(msg[off])
+ if endOff > len(msg) {
+ return "", off, errCalcLen
+ }
+ return string(msg[beginOff:endOff]), endOff, nil
+}
+
+func skipText(msg []byte, off int) (int, error) {
+ if off >= len(msg) {
+ return off, errBaseLen
+ }
+ endOff := off + 1 + int(msg[off])
+ if endOff > len(msg) {
+ return off, errCalcLen
+ }
+ return endOff, nil
+}
+
+// packBytes appends the wire format of field to msg.
+func packBytes(msg []byte, field []byte) []byte {
+ return append(msg, field...)
+}
+
+func unpackBytes(msg []byte, off int, field []byte) (int, error) {
+ newOff := off + len(field)
+ if newOff > len(msg) {
+ return off, errBaseLen
+ }
+ copy(field, msg[off:newOff])
+ return newOff, nil
+}
+
+func skipBytes(msg []byte, off int, field []byte) (int, error) {
+ newOff := off + len(field)
+ if newOff > len(msg) {
+ return off, errBaseLen
+ }
+ return newOff, nil
+}
+
+const nameLen = 255
+
+// A Name is a non-encoded domain name. It is used instead of strings to avoid
+// allocations.
+type Name struct {
+ Data [nameLen]byte
+ Length uint8
+}
+
+// NewName creates a new Name from a string.
+func NewName(name string) (Name, error) {
+ if len([]byte(name)) > nameLen {
+ return Name{}, errCalcLen
+ }
+ n := Name{Length: uint8(len(name))}
+ copy(n.Data[:], []byte(name))
+ return n, nil
+}
+
+// MustNewName creates a new Name from a string and panics on error.
+func MustNewName(name string) Name {
+ n, err := NewName(name)
+ if err != nil {
+ panic("creating name: " + err.Error())
+ }
+ return n
+}
+
+// String implements fmt.Stringer.String.
+func (n Name) String() string {
+ return string(n.Data[:n.Length])
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (n *Name) GoString() string {
+ return `dnsmessage.MustNewName("` + printString(n.Data[:n.Length]) + `")`
+}
+
+// pack appends the wire format of the Name to msg.
+//
+// Domain names are a sequence of counted strings split at the dots. They end
+// with a zero-length string. Compression can be used to reuse domain suffixes.
+//
+// The compression map will be updated with new domain suffixes. If compression
+// is nil, compression will not be used.
+func (n *Name) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ oldMsg := msg
+
+ // Add a trailing dot to canonicalize name.
+ if n.Length == 0 || n.Data[n.Length-1] != '.' {
+ return oldMsg, errNonCanonicalName
+ }
+
+ // Allow root domain.
+ if n.Data[0] == '.' && n.Length == 1 {
+ return append(msg, 0), nil
+ }
+
+ // Emit sequence of counted strings, chopping at dots.
+ for i, begin := 0, 0; i < int(n.Length); i++ {
+ // Check for the end of the segment.
+ if n.Data[i] == '.' {
+ // The two most significant bits have special meaning.
+ // It isn't allowed for segments to be long enough to
+ // need them.
+ if i-begin >= 1<<6 {
+ return oldMsg, errSegTooLong
+ }
+
+ // Segments must have a non-zero length.
+ if i-begin == 0 {
+ return oldMsg, errZeroSegLen
+ }
+
+ msg = append(msg, byte(i-begin))
+
+ for j := begin; j < i; j++ {
+ msg = append(msg, n.Data[j])
+ }
+
+ begin = i + 1
+ continue
+ }
+
+ // We can only compress domain suffixes starting with a new
+ // segment. A pointer is two bytes with the two most significant
+ // bits set to 1 to indicate that it is a pointer.
+ if (i == 0 || n.Data[i-1] == '.') && compression != nil {
+ if ptr, ok := compression[string(n.Data[i:])]; ok {
+ // Hit. Emit a pointer instead of the rest of
+ // the domain.
+ return append(msg, byte(ptr>>8|0xC0), byte(ptr)), nil
+ }
+
+ // Miss. Add the suffix to the compression table if the
+ // offset can be stored in the available 14 bytes.
+ if len(msg) <= int(^uint16(0)>>2) {
+ compression[string(n.Data[i:])] = len(msg) - compressionOff
+ }
+ }
+ }
+ return append(msg, 0), nil
+}
+
+// unpack unpacks a domain name.
+func (n *Name) unpack(msg []byte, off int) (int, error) {
+ return n.unpackCompressed(msg, off, true /* allowCompression */)
+}
+
+func (n *Name) unpackCompressed(msg []byte, off int, allowCompression bool) (int, error) {
+ // currOff is the current working offset.
+ currOff := off
+
+ // newOff is the offset where the next record will start. Pointers lead
+ // to data that belongs to other names and thus doesn't count towards to
+ // the usage of this name.
+ newOff := off
+
+ // ptr is the number of pointers followed.
+ var ptr int
+
+ // Name is a slice representation of the name data.
+ name := n.Data[:0]
+
+Loop:
+ for {
+ if currOff >= len(msg) {
+ return off, errBaseLen
+ }
+ c := int(msg[currOff])
+ currOff++
+ switch c & 0xC0 {
+ case 0x00: // String segment
+ if c == 0x00 {
+ // A zero length signals the end of the name.
+ break Loop
+ }
+ endOff := currOff + c
+ if endOff > len(msg) {
+ return off, errCalcLen
+ }
+ name = append(name, msg[currOff:endOff]...)
+ name = append(name, '.')
+ currOff = endOff
+ case 0xC0: // Pointer
+ if !allowCompression {
+ return off, errCompressedSRV
+ }
+ if currOff >= len(msg) {
+ return off, errInvalidPtr
+ }
+ c1 := msg[currOff]
+ currOff++
+ if ptr == 0 {
+ newOff = currOff
+ }
+ // Don't follow too many pointers, maybe there's a loop.
+ if ptr++; ptr > 10 {
+ return off, errTooManyPtr
+ }
+ currOff = (c^0xC0)<<8 | int(c1)
+ default:
+ // Prefixes 0x80 and 0x40 are reserved.
+ return off, errReserved
+ }
+ }
+ if len(name) == 0 {
+ name = append(name, '.')
+ }
+ if len(name) > len(n.Data) {
+ return off, errCalcLen
+ }
+ n.Length = uint8(len(name))
+ if ptr == 0 {
+ newOff = currOff
+ }
+ return newOff, nil
+}
+
+func skipName(msg []byte, off int) (int, error) {
+ // newOff is the offset where the next record will start. Pointers lead
+ // to data that belongs to other names and thus doesn't count towards to
+ // the usage of this name.
+ newOff := off
+
+Loop:
+ for {
+ if newOff >= len(msg) {
+ return off, errBaseLen
+ }
+ c := int(msg[newOff])
+ newOff++
+ switch c & 0xC0 {
+ case 0x00:
+ if c == 0x00 {
+ // A zero length signals the end of the name.
+ break Loop
+ }
+ // literal string
+ newOff += c
+ if newOff > len(msg) {
+ return off, errCalcLen
+ }
+ case 0xC0:
+ // Pointer to somewhere else in msg.
+
+ // Pointers are two bytes.
+ newOff++
+
+ // Don't follow the pointer as the data here has ended.
+ break Loop
+ default:
+ // Prefixes 0x80 and 0x40 are reserved.
+ return off, errReserved
+ }
+ }
+
+ return newOff, nil
+}
+
+// A Question is a DNS query.
+type Question struct {
+ Name Name
+ Type Type
+ Class Class
+}
+
+// pack appends the wire format of the Question to msg.
+func (q *Question) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ msg, err := q.Name.pack(msg, compression, compressionOff)
+ if err != nil {
+ return msg, &nestedError{"Name", err}
+ }
+ msg = packType(msg, q.Type)
+ return packClass(msg, q.Class), nil
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (q *Question) GoString() string {
+ return "dnsmessage.Question{" +
+ "Name: " + q.Name.GoString() + ", " +
+ "Type: " + q.Type.GoString() + ", " +
+ "Class: " + q.Class.GoString() + "}"
+}
+
+func unpackResourceBody(msg []byte, off int, hdr ResourceHeader) (ResourceBody, int, error) {
+ var (
+ r ResourceBody
+ err error
+ name string
+ )
+ switch hdr.Type {
+ case TypeA:
+ var rb AResource
+ rb, err = unpackAResource(msg, off)
+ r = &rb
+ name = "A"
+ case TypeNS:
+ var rb NSResource
+ rb, err = unpackNSResource(msg, off)
+ r = &rb
+ name = "NS"
+ case TypeCNAME:
+ var rb CNAMEResource
+ rb, err = unpackCNAMEResource(msg, off)
+ r = &rb
+ name = "CNAME"
+ case TypeSOA:
+ var rb SOAResource
+ rb, err = unpackSOAResource(msg, off)
+ r = &rb
+ name = "SOA"
+ case TypePTR:
+ var rb PTRResource
+ rb, err = unpackPTRResource(msg, off)
+ r = &rb
+ name = "PTR"
+ case TypeMX:
+ var rb MXResource
+ rb, err = unpackMXResource(msg, off)
+ r = &rb
+ name = "MX"
+ case TypeTXT:
+ var rb TXTResource
+ rb, err = unpackTXTResource(msg, off, hdr.Length)
+ r = &rb
+ name = "TXT"
+ case TypeAAAA:
+ var rb AAAAResource
+ rb, err = unpackAAAAResource(msg, off)
+ r = &rb
+ name = "AAAA"
+ case TypeSRV:
+ var rb SRVResource
+ rb, err = unpackSRVResource(msg, off)
+ r = &rb
+ name = "SRV"
+ case TypeOPT:
+ var rb OPTResource
+ rb, err = unpackOPTResource(msg, off, hdr.Length)
+ r = &rb
+ name = "OPT"
+ }
+ if err != nil {
+ return nil, off, &nestedError{name + " record", err}
+ }
+ if r == nil {
+ return nil, off, errors.New("invalid resource type: " + string(hdr.Type+'0'))
+ }
+ return r, off + int(hdr.Length), nil
+}
+
+// A CNAMEResource is a CNAME Resource record.
+type CNAMEResource struct {
+ CNAME Name
+}
+
+func (r *CNAMEResource) realType() Type {
+ return TypeCNAME
+}
+
+// pack appends the wire format of the CNAMEResource to msg.
+func (r *CNAMEResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ return r.CNAME.pack(msg, compression, compressionOff)
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (r *CNAMEResource) GoString() string {
+ return "dnsmessage.CNAMEResource{CNAME: " + r.CNAME.GoString() + "}"
+}
+
+func unpackCNAMEResource(msg []byte, off int) (CNAMEResource, error) {
+ var cname Name
+ if _, err := cname.unpack(msg, off); err != nil {
+ return CNAMEResource{}, err
+ }
+ return CNAMEResource{cname}, nil
+}
+
+// An MXResource is an MX Resource record.
+type MXResource struct {
+ Pref uint16
+ MX Name
+}
+
+func (r *MXResource) realType() Type {
+ return TypeMX
+}
+
+// pack appends the wire format of the MXResource to msg.
+func (r *MXResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ oldMsg := msg
+ msg = packUint16(msg, r.Pref)
+ msg, err := r.MX.pack(msg, compression, compressionOff)
+ if err != nil {
+ return oldMsg, &nestedError{"MXResource.MX", err}
+ }
+ return msg, nil
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (r *MXResource) GoString() string {
+ return "dnsmessage.MXResource{" +
+ "Pref: " + printUint16(r.Pref) + ", " +
+ "MX: " + r.MX.GoString() + "}"
+}
+
+func unpackMXResource(msg []byte, off int) (MXResource, error) {
+ pref, off, err := unpackUint16(msg, off)
+ if err != nil {
+ return MXResource{}, &nestedError{"Pref", err}
+ }
+ var mx Name
+ if _, err := mx.unpack(msg, off); err != nil {
+ return MXResource{}, &nestedError{"MX", err}
+ }
+ return MXResource{pref, mx}, nil
+}
+
+// An NSResource is an NS Resource record.
+type NSResource struct {
+ NS Name
+}
+
+func (r *NSResource) realType() Type {
+ return TypeNS
+}
+
+// pack appends the wire format of the NSResource to msg.
+func (r *NSResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ return r.NS.pack(msg, compression, compressionOff)
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (r *NSResource) GoString() string {
+ return "dnsmessage.NSResource{NS: " + r.NS.GoString() + "}"
+}
+
+func unpackNSResource(msg []byte, off int) (NSResource, error) {
+ var ns Name
+ if _, err := ns.unpack(msg, off); err != nil {
+ return NSResource{}, err
+ }
+ return NSResource{ns}, nil
+}
+
+// A PTRResource is a PTR Resource record.
+type PTRResource struct {
+ PTR Name
+}
+
+func (r *PTRResource) realType() Type {
+ return TypePTR
+}
+
+// pack appends the wire format of the PTRResource to msg.
+func (r *PTRResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ return r.PTR.pack(msg, compression, compressionOff)
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (r *PTRResource) GoString() string {
+ return "dnsmessage.PTRResource{PTR: " + r.PTR.GoString() + "}"
+}
+
+func unpackPTRResource(msg []byte, off int) (PTRResource, error) {
+ var ptr Name
+ if _, err := ptr.unpack(msg, off); err != nil {
+ return PTRResource{}, err
+ }
+ return PTRResource{ptr}, nil
+}
+
+// An SOAResource is an SOA Resource record.
+type SOAResource struct {
+ NS Name
+ MBox Name
+ Serial uint32
+ Refresh uint32
+ Retry uint32
+ Expire uint32
+
+ // MinTTL the is the default TTL of Resources records which did not
+ // contain a TTL value and the TTL of negative responses. (RFC 2308
+ // Section 4)
+ MinTTL uint32
+}
+
+func (r *SOAResource) realType() Type {
+ return TypeSOA
+}
+
+// pack appends the wire format of the SOAResource to msg.
+func (r *SOAResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ oldMsg := msg
+ msg, err := r.NS.pack(msg, compression, compressionOff)
+ if err != nil {
+ return oldMsg, &nestedError{"SOAResource.NS", err}
+ }
+ msg, err = r.MBox.pack(msg, compression, compressionOff)
+ if err != nil {
+ return oldMsg, &nestedError{"SOAResource.MBox", err}
+ }
+ msg = packUint32(msg, r.Serial)
+ msg = packUint32(msg, r.Refresh)
+ msg = packUint32(msg, r.Retry)
+ msg = packUint32(msg, r.Expire)
+ return packUint32(msg, r.MinTTL), nil
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (r *SOAResource) GoString() string {
+ return "dnsmessage.SOAResource{" +
+ "NS: " + r.NS.GoString() + ", " +
+ "MBox: " + r.MBox.GoString() + ", " +
+ "Serial: " + printUint32(r.Serial) + ", " +
+ "Refresh: " + printUint32(r.Refresh) + ", " +
+ "Retry: " + printUint32(r.Retry) + ", " +
+ "Expire: " + printUint32(r.Expire) + ", " +
+ "MinTTL: " + printUint32(r.MinTTL) + "}"
+}
+
+func unpackSOAResource(msg []byte, off int) (SOAResource, error) {
+ var ns Name
+ off, err := ns.unpack(msg, off)
+ if err != nil {
+ return SOAResource{}, &nestedError{"NS", err}
+ }
+ var mbox Name
+ if off, err = mbox.unpack(msg, off); err != nil {
+ return SOAResource{}, &nestedError{"MBox", err}
+ }
+ serial, off, err := unpackUint32(msg, off)
+ if err != nil {
+ return SOAResource{}, &nestedError{"Serial", err}
+ }
+ refresh, off, err := unpackUint32(msg, off)
+ if err != nil {
+ return SOAResource{}, &nestedError{"Refresh", err}
+ }
+ retry, off, err := unpackUint32(msg, off)
+ if err != nil {
+ return SOAResource{}, &nestedError{"Retry", err}
+ }
+ expire, off, err := unpackUint32(msg, off)
+ if err != nil {
+ return SOAResource{}, &nestedError{"Expire", err}
+ }
+ minTTL, _, err := unpackUint32(msg, off)
+ if err != nil {
+ return SOAResource{}, &nestedError{"MinTTL", err}
+ }
+ return SOAResource{ns, mbox, serial, refresh, retry, expire, minTTL}, nil
+}
+
+// A TXTResource is a TXT Resource record.
+type TXTResource struct {
+ TXT []string
+}
+
+func (r *TXTResource) realType() Type {
+ return TypeTXT
+}
+
+// pack appends the wire format of the TXTResource to msg.
+func (r *TXTResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ oldMsg := msg
+ for _, s := range r.TXT {
+ var err error
+ msg, err = packText(msg, s)
+ if err != nil {
+ return oldMsg, err
+ }
+ }
+ return msg, nil
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (r *TXTResource) GoString() string {
+ s := "dnsmessage.TXTResource{TXT: []string{"
+ if len(r.TXT) == 0 {
+ return s + "}}"
+ }
+ s += `"` + printString([]byte(r.TXT[0]))
+ for _, t := range r.TXT[1:] {
+ s += `", "` + printString([]byte(t))
+ }
+ return s + `"}}`
+}
+
+func unpackTXTResource(msg []byte, off int, length uint16) (TXTResource, error) {
+ txts := make([]string, 0, 1)
+ for n := uint16(0); n < length; {
+ var t string
+ var err error
+ if t, off, err = unpackText(msg, off); err != nil {
+ return TXTResource{}, &nestedError{"text", err}
+ }
+ // Check if we got too many bytes.
+ if length-n < uint16(len(t))+1 {
+ return TXTResource{}, errCalcLen
+ }
+ n += uint16(len(t)) + 1
+ txts = append(txts, t)
+ }
+ return TXTResource{txts}, nil
+}
+
+// An SRVResource is an SRV Resource record.
+type SRVResource struct {
+ Priority uint16
+ Weight uint16
+ Port uint16
+ Target Name // Not compressed as per RFC 2782.
+}
+
+func (r *SRVResource) realType() Type {
+ return TypeSRV
+}
+
+// pack appends the wire format of the SRVResource to msg.
+func (r *SRVResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ oldMsg := msg
+ msg = packUint16(msg, r.Priority)
+ msg = packUint16(msg, r.Weight)
+ msg = packUint16(msg, r.Port)
+ msg, err := r.Target.pack(msg, nil, compressionOff)
+ if err != nil {
+ return oldMsg, &nestedError{"SRVResource.Target", err}
+ }
+ return msg, nil
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (r *SRVResource) GoString() string {
+ return "dnsmessage.SRVResource{" +
+ "Priority: " + printUint16(r.Priority) + ", " +
+ "Weight: " + printUint16(r.Weight) + ", " +
+ "Port: " + printUint16(r.Port) + ", " +
+ "Target: " + r.Target.GoString() + "}"
+}
+
+func unpackSRVResource(msg []byte, off int) (SRVResource, error) {
+ priority, off, err := unpackUint16(msg, off)
+ if err != nil {
+ return SRVResource{}, &nestedError{"Priority", err}
+ }
+ weight, off, err := unpackUint16(msg, off)
+ if err != nil {
+ return SRVResource{}, &nestedError{"Weight", err}
+ }
+ port, off, err := unpackUint16(msg, off)
+ if err != nil {
+ return SRVResource{}, &nestedError{"Port", err}
+ }
+ var target Name
+ if _, err := target.unpackCompressed(msg, off, false /* allowCompression */); err != nil {
+ return SRVResource{}, &nestedError{"Target", err}
+ }
+ return SRVResource{priority, weight, port, target}, nil
+}
+
+// An AResource is an A Resource record.
+type AResource struct {
+ A [4]byte
+}
+
+func (r *AResource) realType() Type {
+ return TypeA
+}
+
+// pack appends the wire format of the AResource to msg.
+func (r *AResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ return packBytes(msg, r.A[:]), nil
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (r *AResource) GoString() string {
+ return "dnsmessage.AResource{" +
+ "A: [4]byte{" + printByteSlice(r.A[:]) + "}}"
+}
+
+func unpackAResource(msg []byte, off int) (AResource, error) {
+ var a [4]byte
+ if _, err := unpackBytes(msg, off, a[:]); err != nil {
+ return AResource{}, err
+ }
+ return AResource{a}, nil
+}
+
+// An AAAAResource is an AAAA Resource record.
+type AAAAResource struct {
+ AAAA [16]byte
+}
+
+func (r *AAAAResource) realType() Type {
+ return TypeAAAA
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (r *AAAAResource) GoString() string {
+ return "dnsmessage.AAAAResource{" +
+ "AAAA: [16]byte{" + printByteSlice(r.AAAA[:]) + "}}"
+}
+
+// pack appends the wire format of the AAAAResource to msg.
+func (r *AAAAResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ return packBytes(msg, r.AAAA[:]), nil
+}
+
+func unpackAAAAResource(msg []byte, off int) (AAAAResource, error) {
+ var aaaa [16]byte
+ if _, err := unpackBytes(msg, off, aaaa[:]); err != nil {
+ return AAAAResource{}, err
+ }
+ return AAAAResource{aaaa}, nil
+}
+
+// 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
+}
+
+// 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 // option code
+ Data []byte
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (o *Option) GoString() string {
+ return "dnsmessage.Option{" +
+ "Code: " + printUint16(o.Code) + ", " +
+ "Data: []byte{" + printByteSlice(o.Data) + "}}"
+}
+
+func (r *OPTResource) realType() Type {
+ return TypeOPT
+}
+
+func (r *OPTResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) {
+ for _, opt := range r.Options {
+ msg = packUint16(msg, opt.Code)
+ l := uint16(len(opt.Data))
+ msg = packUint16(msg, l)
+ msg = packBytes(msg, opt.Data)
+ }
+ return msg, nil
+}
+
+// GoString implements fmt.GoStringer.GoString.
+func (r *OPTResource) GoString() string {
+ s := "dnsmessage.OPTResource{Options: []dnsmessage.Option{"
+ if len(r.Options) == 0 {
+ return s + "}}"
+ }
+ s += r.Options[0].GoString()
+ for _, o := range r.Options[1:] {
+ s += ", " + o.GoString()
+ }
+ return s + "}}"
+}
+
+func unpackOPTResource(msg []byte, off int, length uint16) (OPTResource, error) {
+ var opts []Option
+ for oldOff := off; off < oldOff+int(length); {
+ var err error
+ var o Option
+ o.Code, off, err = unpackUint16(msg, off)
+ if err != nil {
+ return OPTResource{}, &nestedError{"Code", err}
+ }
+ var l uint16
+ l, off, err = unpackUint16(msg, off)
+ if err != nil {
+ return OPTResource{}, &nestedError{"Data", err}
+ }
+ o.Data = make([]byte, l)
+ if copy(o.Data, msg[off:]) != int(l) {
+ return OPTResource{}, &nestedError{"Data", errCalcLen}
+ }
+ off += int(l)
+ opts = append(opts, o)
+ }
+ return OPTResource{opts}, nil
+}