diff options
Diffstat (limited to 'vendor/golang.org/x/net/dns/dnsmessage/message.go')
-rw-r--r-- | vendor/golang.org/x/net/dns/dnsmessage/message.go | 2034 |
1 files changed, 0 insertions, 2034 deletions
diff --git a/vendor/golang.org/x/net/dns/dnsmessage/message.go b/vendor/golang.org/x/net/dns/dnsmessage/message.go deleted file mode 100644 index e98fda66e..000000000 --- a/vendor/golang.org/x/net/dns/dnsmessage/message.go +++ /dev/null @@ -1,2034 +0,0 @@ -// 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. -// -// 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 - -// A Class is a type of network. -type Class uint16 - -// An OpCode is a DNS operation code. -type OpCode uint16 - -// An RCode is a DNS response status code. -type RCode uint16 - -// Wire constants. -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 - - // Question.Type - TypeWKS Type = 11 - TypeHINFO Type = 13 - TypeMINFO Type = 14 - TypeAXFR Type = 252 - TypeALL Type = 255 - - // ResourceHeader.Class and Question.Class - ClassINET Class = 1 - ClassCSNET Class = 2 - ClassCHAOS Class = 3 - ClassHESIOD Class = 4 - - // Question.Class - ClassANY Class = 255 - - // Message.Rcode - RCodeSuccess RCode = 0 - RCodeFormatError RCode = 1 - RCodeServerFailure RCode = 2 - RCodeNameError RCode = 3 - RCodeNotImplemented RCode = 4 - RCodeRefused RCode = 5 -) - -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 .)") -) - -// 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 -} - -// 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 -} - -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 -} - -// 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) ([]byte, error) - - // realType returns the actual type of the Resource. This is used to - // fill in the header Type field. - realType() Type -} - -func (r *Resource) pack(msg []byte, compression map[string]int) ([]byte, error) { - if r.Body == nil { - return msg, errNilResouceBody - } - oldMsg := msg - r.Header.Type = r.Body.realType() - msg, length, err := r.Header.pack(msg, compression) - if err != nil { - return msg, &nestedError{"ResourceHeader", err} - } - preLen := len(msg) - msg, err = r.Body.pack(msg, compression) - if err != nil { - return msg, &nestedError{"content", err} - } - if err := r.Header.fixLen(msg, length, 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 -} - -// 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)) - - 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); 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); 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); 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); err != nil { - return nil, &nestedError{"packing Additional", err} - } - } - - return msg, nil -} - -// A Builder allows incrementally packing a DNS message. -type Builder struct { - msg []byte - header header - section section - compression map[string]int -} - -// Start initializes the builder. -// -// buf is optional (nil is fine), but if provided, Start takes ownership of buf. -func (b *Builder) Start(buf []byte, h Header) { - b.StartWithoutCompression(buf, h) - b.compression = map[string]int{} -} - -// StartWithoutCompression initializes the builder with compression disabled. -// -// This 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. -// -// buf is optional (nil is fine), but if provided, Start takes ownership of buf. -func (b *Builder) StartWithoutCompression(buf []byte, h Header) { - *b = Builder{msg: buf} - b.header.id, b.header.bits = h.pack() - if cap(b.msg) < headerLen { - b.msg = make([]byte, 0, packStartingCap) - } - b.msg = b.msg[:headerLen] - b.section = sectionHeader -} - -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) - 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, length, err := h.pack(b.msg, b.compression) - if err != nil { - return &nestedError{"ResourceHeader", err} - } - preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { - return &nestedError{"CNAMEResource body", err} - } - if err := h.fixLen(msg, length, 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, length, err := h.pack(b.msg, b.compression) - if err != nil { - return &nestedError{"ResourceHeader", err} - } - preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { - return &nestedError{"MXResource body", err} - } - if err := h.fixLen(msg, length, 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, length, err := h.pack(b.msg, b.compression) - if err != nil { - return &nestedError{"ResourceHeader", err} - } - preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { - return &nestedError{"NSResource body", err} - } - if err := h.fixLen(msg, length, 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, length, err := h.pack(b.msg, b.compression) - if err != nil { - return &nestedError{"ResourceHeader", err} - } - preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { - return &nestedError{"PTRResource body", err} - } - if err := h.fixLen(msg, length, 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, length, err := h.pack(b.msg, b.compression) - if err != nil { - return &nestedError{"ResourceHeader", err} - } - preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { - return &nestedError{"SOAResource body", err} - } - if err := h.fixLen(msg, length, 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, length, err := h.pack(b.msg, b.compression) - if err != nil { - return &nestedError{"ResourceHeader", err} - } - preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { - return &nestedError{"TXTResource body", err} - } - if err := h.fixLen(msg, length, 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, length, err := h.pack(b.msg, b.compression) - if err != nil { - return &nestedError{"ResourceHeader", err} - } - preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { - return &nestedError{"SRVResource body", err} - } - if err := h.fixLen(msg, length, 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, length, err := h.pack(b.msg, b.compression) - if err != nil { - return &nestedError{"ResourceHeader", err} - } - preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { - return &nestedError{"AResource body", err} - } - if err := h.fixLen(msg, length, 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, length, err := h.pack(b.msg, b.compression) - if err != nil { - return &nestedError{"ResourceHeader", err} - } - preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { - return &nestedError{"AAAAResource body", err} - } - if err := h.fixLen(msg, length, 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 - b.header.pack(b.msg[:0]) - 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 -} - -// pack packs all of the fields in a ResourceHeader except for the length. The -// length bytes are returned as a slice so they can be filled in after the rest -// of the Resource has been packed. -func (h *ResourceHeader) pack(oldMsg []byte, compression map[string]int) (msg []byte, length []byte, err error) { - msg = oldMsg - if msg, err = h.Name.pack(msg, compression); err != nil { - return oldMsg, nil, &nestedError{"Name", err} - } - msg = packType(msg, h.Type) - msg = packClass(msg, h.Class) - msg = packUint32(msg, h.TTL) - lenBegin := len(msg) - msg = packUint16(msg, h.Length) - return msg, msg[lenBegin : lenBegin+uint16Len], 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 -} - -func (h *ResourceHeader) fixLen(msg []byte, length []byte, 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(length[:0], uint16(conLen)) - h.Length = uint16(conLen) - - return nil -} - -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 -} - -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 -} - -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) -} - -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) -} - -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 -} - -func packText(msg []byte, field string) []byte { - for len(field) > 0 { - l := len(field) - if l > 255 { - l = 255 - } - msg = append(msg, byte(l)) - msg = append(msg, field[:l]...) - field = field[l:] - } - return msg -} - -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 -} - -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 -} - -func (n Name) String() string { - return string(n.Data[:n.Length]) -} - -// pack packs a domain name. -// -// 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) ([]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) - } - } - } - return append(msg, 0), nil -} - -// unpack unpacks a domain name. -func (n *Name) unpack(msg []byte, off int) (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 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 -} - -func (q *Question) pack(msg []byte, compression map[string]int) ([]byte, error) { - msg, err := q.Name.pack(msg, compression) - if err != nil { - return msg, &nestedError{"Name", err} - } - msg = packType(msg, q.Type) - return packClass(msg, q.Class), nil -} - -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" - } - 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 -} - -func (r *CNAMEResource) pack(msg []byte, compression map[string]int) ([]byte, error) { - return r.CNAME.pack(msg, compression) -} - -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 -} - -func (r *MXResource) pack(msg []byte, compression map[string]int) ([]byte, error) { - oldMsg := msg - msg = packUint16(msg, r.Pref) - msg, err := r.MX.pack(msg, compression) - if err != nil { - return oldMsg, &nestedError{"MXResource.MX", err} - } - return msg, nil -} - -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 -} - -func (r *NSResource) pack(msg []byte, compression map[string]int) ([]byte, error) { - return r.NS.pack(msg, compression) -} - -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 -} - -func (r *PTRResource) pack(msg []byte, compression map[string]int) ([]byte, error) { - return r.PTR.pack(msg, compression) -} - -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 -} - -func (r *SOAResource) pack(msg []byte, compression map[string]int) ([]byte, error) { - oldMsg := msg - msg, err := r.NS.pack(msg, compression) - if err != nil { - return oldMsg, &nestedError{"SOAResource.NS", err} - } - msg, err = r.MBox.pack(msg, compression) - 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 -} - -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 // Not a domain name. -} - -func (r *TXTResource) realType() Type { - return TypeTXT -} - -func (r *TXTResource) pack(msg []byte, compression map[string]int) ([]byte, error) { - return packText(msg, r.Txt), nil -} - -func unpackTXTResource(msg []byte, off int, length uint16) (TXTResource, error) { - var txt string - 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 - txt += t - } - return TXTResource{txt}, 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 -} - -func (r *SRVResource) pack(msg []byte, compression map[string]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) - if err != nil { - return oldMsg, &nestedError{"SRVResource.Target", err} - } - return msg, nil -} - -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.unpack(msg, off); 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 -} - -func (r *AResource) pack(msg []byte, compression map[string]int) ([]byte, error) { - return packBytes(msg, r.A[:]), nil -} - -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 -} - -func (r *AAAAResource) pack(msg []byte, compression map[string]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 -} |