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📄 example_test.go // Copyright 2017 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_test import ( "fmt" "net" "strings" "golang.org/x/net/dns/dnsmessage" ) func ExampleParser() { msg := dnsmessage.Message{ Header: dnsmessage.Header{Response: true, Authoritative: true}, Questions: []dnsmessage.Question{ { Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeA, Class: dnsmessage.ClassINET, }, { Name: dnsmessage.MustNewName("bar.example.com."), Type: dnsmessage.TypeA, Class: dnsmessage.ClassINET, }, }, Answers: []dnsmessage.Resource{ { Header: dnsmessage.ResourceHeader{ Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeA, Class: dnsmessage.ClassINET, }, Body: &dnsmessage.AResource{A: [4]byte{127, 0, 0, 1}}, }, { Header: dnsmessage.ResourceHeader{ Name: dnsmessage.MustNewName("bar.example.com."), Type: dnsmessage.TypeA, Class: dnsmessage.ClassINET, }, Body: &dnsmessage.AResource{A: [4]byte{127, 0, 0, 2}}, }, }, } buf, err := msg.Pack() if err != nil { panic(err) } wantName := "bar.example.com." var p dnsmessage.Parser if _, err := p.Start(buf); err != nil { panic(err) } for { q, err := p.Question() if err == dnsmessage.ErrSectionDone { break } if err != nil { panic(err) } if q.Name.String() != wantName { continue } fmt.Println("Found question for name", wantName) if err := p.SkipAllQuestions(); err != nil { panic(err) } break } var gotIPs []net.IP for { h, err := p.AnswerHeader() if err == dnsmessage.ErrSectionDone { break } if err != nil { panic(err) } if (h.Type != dnsmessage.TypeA && h.Type != dnsmessage.TypeAAAA) \|\| h.Class != dnsmessage.ClassINET { continue } if !strings.EqualFold(h.Name.String(), wantName) { if err := p.SkipAnswer(); err != nil { panic(err) } continue } switch h.Type { case dnsmessage.TypeA: r, err := p.AResource() if err != nil { panic(err) } gotIPs = append(gotIPs, r.A[:]) case dnsmessage.TypeAAAA: r, err := p.AAAAResource() if err != nil { panic(err) } gotIPs = append(gotIPs, r.AAAA[:]) } } fmt.Printf("Found A/AAAA records for name %s: %v\n", wantName, gotIPs) // Output: // Found question for name bar.example.com. // Found A/AAAA records for name bar.example.com.: [127.0.0.2] }	2.49 KB	2025-05-25 12:27
📄 message.go // 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 // Header.RCode values. const ( RCodeSuccess RCode = 0 // NoError RCodeFormatError RCode = 1 // FormErr RCodeServerFailure RCode = 2 // ServFail RCodeNameError RCode = 3 // NXDomain RCodeNotImplemented RCode = 4 // NotImp RCodeRefused RCode = 5 // Refused ) 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, 5len(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") errInvalidName = errors.New("invalid dns name") errNilResouceBody = errors.New("nil resource body") errResourceLen = errors.New("insufficient data for resource body length") errSegTooLong = errors.New("segment length too long") errNameTooLong = errors.New("name 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)") ) // 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 AuthenticData bool CheckingDisabled 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 } if m.AuthenticData { bits \|= headerBitAD } if m.CheckingDisabled { bits \|= headerBitCD } 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) + ", " + "AuthenticData: " + printBool(m.AuthenticData) + ", " + "CheckingDisabled: " + printBool(m.CheckingDisabled) + ", " + "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 headerBitAD = 1 << 5 // authentic data headerBitCD = 1 << 4 // checking disabled ) 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, AuthenticData: (h.bits & headerBitAD) != 0, CheckingDisabled: (h.bits & headerBitCD) != 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]uint16, 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]uint16, 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 the [ErrSectionDone] error. // After all Questions have been either parsed or skipped, all // Answers, Authorities and Additionals can be either parsed or skipped in the // same way, and each type of Resource must be fully parsed or skipped before // proceeding to the next type of Resource. // // Parser is safe to copy to preserve the parsing state. // // Note that there is no requirement to fully skip or parse the message. type Parser struct { msg []byte header header section section off int index int resHeaderValid bool resHeaderOffset int resHeaderType Type resHeaderLength uint16 } // 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 { p.off = p.resHeaderOffset } 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.resHeaderOffset = p.off p.resHeaderType = hdr.Type p.resHeaderLength = hdr.Length p.off = off return hdr, nil } func (p Parser) skipResource(sec section) error { if p.resHeaderValid && p.section == sec { newOff := p.off + int(p.resHeaderLength) 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. // // It does not perform a complete validation of the resource header, which means // it may return a nil error when the [AnswerHeader] would actually return an error. 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. // // It does not perform a complete validation of the resource header, which means // it may return a nil error when the [AuthorityHeader] would actually return an error. 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. // // It does not perform a complete validation of the resource header, which means // it may return a nil error when the [AdditionalHeader] would actually return an error. 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.resHeaderType != TypeCNAME { return CNAMEResource{}, ErrNotStarted } r, err := unpackCNAMEResource(p.msg, p.off) if err != nil { return CNAMEResource{}, err } p.off += int(p.resHeaderLength) 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.resHeaderType != TypeMX { return MXResource{}, ErrNotStarted } r, err := unpackMXResource(p.msg, p.off) if err != nil { return MXResource{}, err } p.off += int(p.resHeaderLength) 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.resHeaderType != TypeNS { return NSResource{}, ErrNotStarted } r, err := unpackNSResource(p.msg, p.off) if err != nil { return NSResource{}, err } p.off += int(p.resHeaderLength) 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.resHeaderType != TypePTR { return PTRResource{}, ErrNotStarted } r, err := unpackPTRResource(p.msg, p.off) if err != nil { return PTRResource{}, err } p.off += int(p.resHeaderLength) 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.resHeaderType != TypeSOA { return SOAResource{}, ErrNotStarted } r, err := unpackSOAResource(p.msg, p.off) if err != nil { return SOAResource{}, err } p.off += int(p.resHeaderLength) 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.resHeaderType != TypeTXT { return TXTResource{}, ErrNotStarted } r, err := unpackTXTResource(p.msg, p.off, p.resHeaderLength) if err != nil { return TXTResource{}, err } p.off += int(p.resHeaderLength) 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.resHeaderType != TypeSRV { return SRVResource{}, ErrNotStarted } r, err := unpackSRVResource(p.msg, p.off) if err != nil { return SRVResource{}, err } p.off += int(p.resHeaderLength) 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.resHeaderType != TypeA { return AResource{}, ErrNotStarted } r, err := unpackAResource(p.msg, p.off) if err != nil { return AResource{}, err } p.off += int(p.resHeaderLength) 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.resHeaderType != TypeAAAA { return AAAAResource{}, ErrNotStarted } r, err := unpackAAAAResource(p.msg, p.off) if err != nil { return AAAAResource{}, err } p.off += int(p.resHeaderLength) 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.resHeaderType != TypeOPT { return OPTResource{}, ErrNotStarted } r, err := unpackOPTResource(p.msg, p.off, p.resHeaderLength) if err != nil { return OPTResource{}, err } p.off += int(p.resHeaderLength) p.resHeaderValid = false p.index++ return r, nil } // UnknownResource parses a single UnknownResource. // // One of the XXXHeader methods must have been called before calling this // method. func (p Parser) UnknownResource() (UnknownResource, error) { if !p.resHeaderValid { return UnknownResource{}, ErrNotStarted } r, err := unpackUnknownResource(p.resHeaderType, p.msg, p.off, p.resHeaderLength) if err != nil { return UnknownResource{}, err } p.off += int(p.resHeaderLength) 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]uint16{} 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]uint16 } // 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 includes buf[:len(buf)] and 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]uint16{} } 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 } // UnknownResource adds a single UnknownResource. func (b Builder) UnknownResource(h ResourceHeader, r UnknownResource) 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{"UnknownResource 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]uint16, 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 constants. const ( edns0Version = 0 edns0DNSSECOK = 0x00008000 ednsVersionMask = 0x00ff0000 edns0DNSSECOKMask = 0x00ff8000 ) // SetEDNS0 configures h for EDNS(0). // // The provided extRCode must be an extended RCode. func (h ResourceHeader) SetEDNS0(udpPayloadLen int, extRCode RCode, dnssecOK bool) error { h.Name = Name{Data: [255]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 } // 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 } const nonEncodedNameMax = 254 // A Name is a non-encoded and non-escaped domain name. It is used instead of strings to avoid // allocations. type Name struct { Data [255]byte Length uint8 } // NewName creates a new Name from a string. func NewName(name string) (Name, error) { n := Name{Length: uint8(len(name))} if len(name) > len(n.Data) { return Name{}, errCalcLen } copy(n.Data[:], 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. // // Note: characters inside the labels are not escaped in any way. 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]uint16, compressionOff int) ([]byte, error) { oldMsg := msg if n.Length > nonEncodedNameMax { return nil, errNameTooLong } // 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 } var nameAsStr string // 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:n.Length])]; 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 bits. newPtr := len(msg) - compressionOff if newPtr <= int(^uint16(0)>>2) { if nameAsStr == "" { // allocate n.Data on the heap once, to avoid allocating it // multiple times (for next labels). nameAsStr = string(n.Data[:n.Length]) } compression[nameAsStr[i:]] = uint16(newPtr) } } } 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 } // Reject names containing dots. // See issue golang/go#56246 for _, v := range msg[currOff:endOff] { if v == '.' { return off, errInvalidName } } 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) > nonEncodedNameMax { return off, errNameTooLong } 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]uint16, 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" default: var rb UnknownResource rb, err = unpackUnknownResource(hdr.Type, msg, off, hdr.Length) r = &rb name = "Unknown" } if err != nil { return nil, off, &nestedError{name + " record", err} } 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]uint16, 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]uint16, 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]uint16, 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]uint16, 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]uint16, 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]uint16, 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]uint16, 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.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 } // pack appends the wire format of the AResource to msg. func (r AResource) pack(msg []byte, compression map[string]uint16, 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]uint16, 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]uint16, 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 } // An UnknownResource is a catch-all container for unknown record types. type UnknownResource struct { Type Type Data []byte } func (r UnknownResource) realType() Type { return r.Type } // pack appends the wire format of the UnknownResource to msg. func (r UnknownResource) pack(msg []byte, compression map[string]uint16, compressionOff int) ([]byte, error) { return packBytes(msg, r.Data[:]), nil } // GoString implements fmt.GoStringer.GoString. func (r UnknownResource) GoString() string { return "dnsmessage.UnknownResource{" + "Type: " + r.Type.GoString() + ", " + "Data: []byte{" + printByteSlice(r.Data) + "}}" } func unpackUnknownResource(recordType Type, msg []byte, off int, length uint16) (UnknownResource, error) { parsed := UnknownResource{ Type: recordType, Data: make([]byte, length), } if _, err := unpackBytes(msg, off, parsed.Data); err != nil { return UnknownResource{}, err } return parsed, nil }	68.97 KB	2025-05-25 12:27
📄 message_test.go // 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 import ( "bytes" "fmt" "os" "path/filepath" "reflect" "strings" "testing" ) const ( // This type was selected randomly from the IANA-assigned private use // range of RR TYPEs. privateUseType Type = 65362 ) func TestPrintPaddedUint8(t testing.T) { tests := []struct { num uint8 want string }{ {0, "000"}, {1, "001"}, {9, "009"}, {10, "010"}, {99, "099"}, {100, "100"}, {124, "124"}, {104, "104"}, {120, "120"}, {255, "255"}, } for _, test := range tests { if got := printPaddedUint8(test.num); got != test.want { t.Errorf("got printPaddedUint8(%d) = %s, want = %s", test.num, got, test.want) } } } func TestPrintUint8Bytes(t testing.T) { tests := []uint8{ 0, 1, 9, 10, 99, 100, 124, 104, 120, 255, } for _, test := range tests { if got, want := string(printUint8Bytes(nil, test)), fmt.Sprint(test); got != want { t.Errorf("got printUint8Bytes(%d) = %s, want = %s", test, got, want) } } } func TestPrintUint16(t testing.T) { tests := []uint16{ 65535, 0, 1, 10, 100, 1000, 10000, 324, 304, 320, } for _, test := range tests { if got, want := printUint16(test), fmt.Sprint(test); got != want { t.Errorf("got printUint16(%d) = %s, want = %s", test, got, want) } } } func TestPrintUint32(t testing.T) { tests := []uint32{ 4294967295, 65535, 0, 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000, 324, 304, 320, } for _, test := range tests { if got, want := printUint32(test), fmt.Sprint(test); got != want { t.Errorf("got printUint32(%d) = %s, want = %s", test, got, want) } } } func mustEDNS0ResourceHeader(l int, extrc RCode, do bool) ResourceHeader { h := ResourceHeader{Class: ClassINET} if err := h.SetEDNS0(l, extrc, do); err != nil { panic(err) } return h } func (m Message) String() string { s := fmt.Sprintf("Message: %#v\n", &m.Header) if len(m.Questions) > 0 { s += "-- Questions\n" for _, q := range m.Questions { s += fmt.Sprintf("%#v\n", q) } } if len(m.Answers) > 0 { s += "-- Answers\n" for _, a := range m.Answers { s += fmt.Sprintf("%#v\n", a) } } if len(m.Authorities) > 0 { s += "-- Authorities\n" for _, ns := range m.Authorities { s += fmt.Sprintf("%#v\n", ns) } } if len(m.Additionals) > 0 { s += "-- Additionals\n" for _, e := range m.Additionals { s += fmt.Sprintf("%#v\n", e) } } return s } func TestNameString(t testing.T) { want := "foo" name := MustNewName(want) if got := fmt.Sprint(name); got != want { t.Errorf("got fmt.Sprint(%#v) = %s, want = %s", name, got, want) } } func TestQuestionPackUnpack(t testing.T) { want := Question{ Name: MustNewName("."), Type: TypeA, Class: ClassINET, } buf, err := want.pack(make([]byte, 1, 50), map[string]uint16{}, 1) if err != nil { t.Fatal("Question.pack() =", err) } var p Parser p.msg = buf p.header.questions = 1 p.section = sectionQuestions p.off = 1 got, err := p.Question() if err != nil { t.Fatalf("Parser{%q}.Question() = %v", string(buf[1:]), err) } if p.off != len(buf) { t.Errorf("unpacked different amount than packed: got = %d, want = %d", p.off, len(buf)) } if !reflect.DeepEqual(got, want) { t.Errorf("got from Parser.Question() = %+v, want = %+v", got, want) } } func TestName(t testing.T) { tests := []string{ "", ".", "google..com", "google.com", "google..com.", "google.com.", ".google.com.", "www..google.com.", "www.google.com.", } for _, test := range tests { n, err := NewName(test) if err != nil { t.Errorf("NewName(%q) = %v", test, err) continue } if ns := n.String(); ns != test { t.Errorf("got %#v.String() = %q, want = %q", n, ns, test) continue } } } func TestNameWithDotsUnpack(t testing.T) { name := []byte{3, 'w', '.', 'w', 2, 'g', 'o', 3, 'd', 'e', 'v', 0} var n Name _, err := n.unpack(name, 0) if err != errInvalidName { t.Fatalf("expected %v, got %v", errInvalidName, err) } } func TestNamePackUnpack(t testing.T) { const suffix = ".go.dev." var longDNSPrefix = strings.Repeat("verylongdomainlabel.", 20) tests := []struct { in string err error }{ {"", errNonCanonicalName}, {".", nil}, {"google..com", errNonCanonicalName}, {"google.com", errNonCanonicalName}, {"google..com.", errZeroSegLen}, {"google.com.", nil}, {".google.com.", errZeroSegLen}, {"www..google.com.", errZeroSegLen}, {"www.google.com.", nil}, {in: longDNSPrefix[:254-len(suffix)] + suffix}, // 254B name, with ending dot. {in: longDNSPrefix[:255-len(suffix)] + suffix, err: errNameTooLong}, // 255B name, with ending dot. } for _, test := range tests { in := MustNewName(test.in) buf, err := in.pack(make([]byte, 0, 30), map[string]uint16{}, 0) if err != test.err { t.Errorf("got %q.pack() = %v, want = %v", test.in, err, test.err) continue } if test.err != nil { continue } var got Name n, err := got.unpack(buf, 0) if err != nil { t.Errorf("%q.unpack() = %v", test.in, err) continue } if n != len(buf) { t.Errorf( "unpacked different amount than packed for %q: got = %d, want = %d", test.in, n, len(buf), ) } if got != in { t.Errorf("unpacking packing of %q: got = %#v, want = %#v", test.in, got, in) } } } func TestNameUnpackTooLongName(t testing.T) { var suffix = []byte{2, 'g', 'o', 3, 'd', 'e', 'v', 0} const label = "longdnslabel" labelBinary := append([]byte{byte(len(label))}, []byte(label)...) var longDNSPrefix = bytes.Repeat(labelBinary, 18) longDNSPrefix = longDNSPrefix[:len(longDNSPrefix):len(longDNSPrefix)] prepName := func(length int) []byte { missing := length - (len(longDNSPrefix) + len(suffix) + 1) name := append(longDNSPrefix, byte(missing)) name = append(name, bytes.Repeat([]byte{'a'}, missing)...) return append(name, suffix...) } tests := []struct { name []byte err error }{ {name: prepName(255)}, {name: prepName(256), err: errNameTooLong}, } for i, test := range tests { var got Name _, err := got.unpack(test.name, 0) if err != test.err { t.Errorf("%v: %v: expected error: %v, got %v", i, test.name, test.err, err) } } } func checkErrorPrefix(err error, prefix string) bool { e, ok := err.(nestedError) return ok && e.s == prefix } func TestHeaderUnpackError(t testing.T) { wants := []string{ "id", "bits", "questions", "answers", "authorities", "additionals", } var buf []byte var h header for _, want := range wants { n, err := h.unpack(buf, 0) if n != 0 \|\| !checkErrorPrefix(err, want) { t.Errorf("got header.unpack([%d]byte, 0) = %d, %v, want = 0, %s", len(buf), n, err, want) } buf = append(buf, 0, 0) } } func TestParserStart(t testing.T) { const want = "unpacking header" var p Parser for i := 0; i <= 1; i++ { _, err := p.Start([]byte{}) if !checkErrorPrefix(err, want) { t.Errorf("got Parser.Start(nil) = _, %v, want = _, %s", err, want) } } } func TestResourceNotStarted(t testing.T) { tests := []struct { name string fn func(Parser) error }{ {"CNAMEResource", func(p Parser) error { _, err := p.CNAMEResource(); return err }}, {"MXResource", func(p Parser) error { _, err := p.MXResource(); return err }}, {"NSResource", func(p Parser) error { _, err := p.NSResource(); return err }}, {"PTRResource", func(p Parser) error { _, err := p.PTRResource(); return err }}, {"SOAResource", func(p Parser) error { _, err := p.SOAResource(); return err }}, {"TXTResource", func(p Parser) error { _, err := p.TXTResource(); return err }}, {"SRVResource", func(p Parser) error { _, err := p.SRVResource(); return err }}, {"AResource", func(p Parser) error { _, err := p.AResource(); return err }}, {"AAAAResource", func(p Parser) error { _, err := p.AAAAResource(); return err }}, {"UnknownResource", func(p Parser) error { _, err := p.UnknownResource(); return err }}, } for _, test := range tests { if err := test.fn(&Parser{}); err != ErrNotStarted { t.Errorf("got Parser.%s() = _ , %v, want = _, %v", test.name, err, ErrNotStarted) } } } func TestDNSPackUnpack(t testing.T) { wants := []Message{ { Questions: []Question{ { Name: MustNewName("."), Type: TypeAAAA, Class: ClassINET, }, }, Answers: []Resource{}, Authorities: []Resource{}, Additionals: []Resource{}, }, largeTestMsg(), } for i, want := range wants { b, err := want.Pack() if err != nil { t.Fatalf("%d: Message.Pack() = %v", i, err) } var got Message err = got.Unpack(b) if err != nil { t.Fatalf("%d: Message.Unapck() = %v", i, err) } if !reflect.DeepEqual(got, want) { t.Errorf("%d: Message.Pack/Unpack() roundtrip: got = %+v, want = %+v", i, &got, &want) } } } func TestDNSAppendPackUnpack(t testing.T) { wants := []Message{ { Questions: []Question{ { Name: MustNewName("."), Type: TypeAAAA, Class: ClassINET, }, }, Answers: []Resource{}, Authorities: []Resource{}, Additionals: []Resource{}, }, largeTestMsg(), } for i, want := range wants { b := make([]byte, 2, 514) b, err := want.AppendPack(b) if err != nil { t.Fatalf("%d: Message.AppendPack() = %v", i, err) } b = b[2:] var got Message err = got.Unpack(b) if err != nil { t.Fatalf("%d: Message.Unapck() = %v", i, err) } if !reflect.DeepEqual(got, want) { t.Errorf("%d: Message.AppendPack/Unpack() roundtrip: got = %+v, want = %+v", i, &got, &want) } } } func TestSkipAll(t testing.T) { msg := largeTestMsg() buf, err := msg.Pack() if err != nil { t.Fatal("Message.Pack() =", err) } var p Parser if _, err := p.Start(buf); err != nil { t.Fatal("Parser.Start(non-nil) =", err) } tests := []struct { name string f func() error }{ {"SkipAllQuestions", p.SkipAllQuestions}, {"SkipAllAnswers", p.SkipAllAnswers}, {"SkipAllAuthorities", p.SkipAllAuthorities}, {"SkipAllAdditionals", p.SkipAllAdditionals}, } for _, test := range tests { for i := 1; i <= 3; i++ { if err := test.f(); err != nil { t.Errorf("%d: Parser.%s() = %v", i, test.name, err) } } } } func TestSkipEach(t testing.T) { msg := smallTestMsg() buf, err := msg.Pack() if err != nil { t.Fatal("Message.Pack() =", err) } var p Parser if _, err := p.Start(buf); err != nil { t.Fatal("Parser.Start(non-nil) =", err) } tests := []struct { name string f func() error }{ {"SkipQuestion", p.SkipQuestion}, {"SkipAnswer", p.SkipAnswer}, {"SkipAuthority", p.SkipAuthority}, {"SkipAdditional", p.SkipAdditional}, } for _, test := range tests { if err := test.f(); err != nil { t.Errorf("first Parser.%s() = %v, want = nil", test.name, err) } if err := test.f(); err != ErrSectionDone { t.Errorf("second Parser.%s() = %v, want = %v", test.name, err, ErrSectionDone) } } } func TestSkipAfterRead(t testing.T) { msg := smallTestMsg() buf, err := msg.Pack() if err != nil { t.Fatal("Message.Pack() =", err) } var p Parser if _, err := p.Start(buf); err != nil { t.Fatal("Parser.Srart(non-nil) =", err) } tests := []struct { name string skip func() error read func() error }{ {"Question", p.SkipQuestion, func() error { _, err := p.Question(); return err }}, {"Answer", p.SkipAnswer, func() error { _, err := p.Answer(); return err }}, {"Authority", p.SkipAuthority, func() error { _, err := p.Authority(); return err }}, {"Additional", p.SkipAdditional, func() error { _, err := p.Additional(); return err }}, } for _, test := range tests { if err := test.read(); err != nil { t.Errorf("got Parser.%s() = _, %v, want = _, nil", test.name, err) } if err := test.skip(); err != ErrSectionDone { t.Errorf("got Parser.Skip%s() = %v, want = %v", test.name, err, ErrSectionDone) } } } func TestSkipNotStarted(t testing.T) { var p Parser tests := []struct { name string f func() error }{ {"SkipAllQuestions", p.SkipAllQuestions}, {"SkipAllAnswers", p.SkipAllAnswers}, {"SkipAllAuthorities", p.SkipAllAuthorities}, {"SkipAllAdditionals", p.SkipAllAdditionals}, } for _, test := range tests { if err := test.f(); err != ErrNotStarted { t.Errorf("got Parser.%s() = %v, want = %v", test.name, err, ErrNotStarted) } } } func TestTooManyRecords(t testing.T) { const recs = int(^uint16(0)) + 1 tests := []struct { name string msg Message want error }{ { "Questions", Message{ Questions: make([]Question, recs), }, errTooManyQuestions, }, { "Answers", Message{ Answers: make([]Resource, recs), }, errTooManyAnswers, }, { "Authorities", Message{ Authorities: make([]Resource, recs), }, errTooManyAuthorities, }, { "Additionals", Message{ Additionals: make([]Resource, recs), }, errTooManyAdditionals, }, } for _, test := range tests { if _, got := test.msg.Pack(); got != test.want { t.Errorf("got Message.Pack() for %d %s = %v, want = %v", recs, test.name, got, test.want) } } } func TestVeryLongTxt(t testing.T) { want := Resource{ ResourceHeader{ Name: MustNewName("foo.bar.example.com."), Type: TypeTXT, Class: ClassINET, }, &TXTResource{[]string{ "", "", "foo bar", "", "www.example.com", "www.example.com.", strings.Repeat(".", 255), }}, } buf, err := want.pack(make([]byte, 0, 8000), map[string]uint16{}, 0) if err != nil { t.Fatal("Resource.pack() =", err) } var got Resource off, err := got.Header.unpack(buf, 0) if err != nil { t.Fatal("ResourceHeader.unpack() =", err) } body, n, err := unpackResourceBody(buf, off, got.Header) if err != nil { t.Fatal("unpackResourceBody() =", err) } got.Body = body if n != len(buf) { t.Errorf("unpacked different amount than packed: got = %d, want = %d", n, len(buf)) } if !reflect.DeepEqual(got, want) { t.Errorf("Resource.pack/unpack() roundtrip: got = %#v, want = %#v", got, want) } } func TestTooLongTxt(t testing.T) { rb := TXTResource{[]string{strings.Repeat(".", 256)}} if _, err := rb.pack(make([]byte, 0, 8000), map[string]uint16{}, 0); err != errStringTooLong { t.Errorf("packing TXTResource with 256 character string: got err = %v, want = %v", err, errStringTooLong) } } func TestStartAppends(t testing.T) { buf := make([]byte, 2, 514) wantBuf := []byte{4, 44} copy(buf, wantBuf) b := NewBuilder(buf, Header{}) b.EnableCompression() buf, err := b.Finish() if err != nil { t.Fatal("Builder.Finish() =", err) } if got, want := len(buf), headerLen+2; got != want { t.Errorf("got len(buf) = %d, want = %d", got, want) } if string(buf[:2]) != string(wantBuf) { t.Errorf("original data not preserved, got = %#v, want = %#v", buf[:2], wantBuf) } } func TestStartError(t testing.T) { tests := []struct { name string fn func(Builder) error }{ {"Questions", func(b Builder) error { return b.StartQuestions() }}, {"Answers", func(b Builder) error { return b.StartAnswers() }}, {"Authorities", func(b Builder) error { return b.StartAuthorities() }}, {"Additionals", func(b Builder) error { return b.StartAdditionals() }}, } envs := []struct { name string fn func() Builder want error }{ {"sectionNotStarted", func() Builder { return &Builder{section: sectionNotStarted} }, ErrNotStarted}, {"sectionDone", func() Builder { return &Builder{section: sectionDone} }, ErrSectionDone}, } for _, env := range envs { for _, test := range tests { if got := test.fn(env.fn()); got != env.want { t.Errorf("got Builder{%s}.Start%s() = %v, want = %v", env.name, test.name, got, env.want) } } } } func TestBuilderResourceError(t testing.T) { tests := []struct { name string fn func(Builder) error }{ {"CNAMEResource", func(b Builder) error { return b.CNAMEResource(ResourceHeader{}, CNAMEResource{}) }}, {"MXResource", func(b Builder) error { return b.MXResource(ResourceHeader{}, MXResource{}) }}, {"NSResource", func(b Builder) error { return b.NSResource(ResourceHeader{}, NSResource{}) }}, {"PTRResource", func(b Builder) error { return b.PTRResource(ResourceHeader{}, PTRResource{}) }}, {"SOAResource", func(b Builder) error { return b.SOAResource(ResourceHeader{}, SOAResource{}) }}, {"TXTResource", func(b Builder) error { return b.TXTResource(ResourceHeader{}, TXTResource{}) }}, {"SRVResource", func(b Builder) error { return b.SRVResource(ResourceHeader{}, SRVResource{}) }}, {"AResource", func(b Builder) error { return b.AResource(ResourceHeader{}, AResource{}) }}, {"AAAAResource", func(b Builder) error { return b.AAAAResource(ResourceHeader{}, AAAAResource{}) }}, {"OPTResource", func(b Builder) error { return b.OPTResource(ResourceHeader{}, OPTResource{}) }}, {"UnknownResource", func(b Builder) error { return b.UnknownResource(ResourceHeader{}, UnknownResource{}) }}, } envs := []struct { name string fn func() Builder want error }{ {"sectionNotStarted", func() Builder { return &Builder{section: sectionNotStarted} }, ErrNotStarted}, {"sectionHeader", func() Builder { return &Builder{section: sectionHeader} }, ErrNotStarted}, {"sectionQuestions", func() Builder { return &Builder{section: sectionQuestions} }, ErrNotStarted}, {"sectionDone", func() Builder { return &Builder{section: sectionDone} }, ErrSectionDone}, } for _, env := range envs { for _, test := range tests { if got := test.fn(env.fn()); got != env.want { t.Errorf("got Builder{%s}.%s() = %v, want = %v", env.name, test.name, got, env.want) } } } } func TestFinishError(t testing.T) { var b Builder want := ErrNotStarted if _, got := b.Finish(); got != want { t.Errorf("got Builder.Finish() = %v, want = %v", got, want) } } func TestBuilder(t testing.T) { msg := largeTestMsg() want, err := msg.Pack() if err != nil { t.Fatal("Message.Pack() =", err) } b := NewBuilder(nil, msg.Header) b.EnableCompression() if err := b.StartQuestions(); err != nil { t.Fatal("Builder.StartQuestions() =", err) } for _, q := range msg.Questions { if err := b.Question(q); err != nil { t.Fatalf("Builder.Question(%#v) = %v", q, err) } } if err := b.StartAnswers(); err != nil { t.Fatal("Builder.StartAnswers() =", err) } for _, a := range msg.Answers { switch a.Header.Type { case TypeA: if err := b.AResource(a.Header, a.Body.(AResource)); err != nil { t.Fatalf("Builder.AResource(%#v) = %v", a, err) } case TypeNS: if err := b.NSResource(a.Header, a.Body.(NSResource)); err != nil { t.Fatalf("Builder.NSResource(%#v) = %v", a, err) } case TypeCNAME: if err := b.CNAMEResource(a.Header, a.Body.(CNAMEResource)); err != nil { t.Fatalf("Builder.CNAMEResource(%#v) = %v", a, err) } case TypeSOA: if err := b.SOAResource(a.Header, a.Body.(SOAResource)); err != nil { t.Fatalf("Builder.SOAResource(%#v) = %v", a, err) } case TypePTR: if err := b.PTRResource(a.Header, a.Body.(PTRResource)); err != nil { t.Fatalf("Builder.PTRResource(%#v) = %v", a, err) } case TypeMX: if err := b.MXResource(a.Header, a.Body.(MXResource)); err != nil { t.Fatalf("Builder.MXResource(%#v) = %v", a, err) } case TypeTXT: if err := b.TXTResource(a.Header, a.Body.(TXTResource)); err != nil { t.Fatalf("Builder.TXTResource(%#v) = %v", a, err) } case TypeAAAA: if err := b.AAAAResource(a.Header, a.Body.(AAAAResource)); err != nil { t.Fatalf("Builder.AAAAResource(%#v) = %v", a, err) } case TypeSRV: if err := b.SRVResource(a.Header, a.Body.(SRVResource)); err != nil { t.Fatalf("Builder.SRVResource(%#v) = %v", a, err) } case privateUseType: if err := b.UnknownResource(a.Header, a.Body.(UnknownResource)); err != nil { t.Fatalf("Builder.UnknownResource(%#v) = %v", a, err) } } } if err := b.StartAuthorities(); err != nil { t.Fatal("Builder.StartAuthorities() =", err) } for _, a := range msg.Authorities { if err := b.NSResource(a.Header, a.Body.(NSResource)); err != nil { t.Fatalf("Builder.NSResource(%#v) = %v", a, err) } } if err := b.StartAdditionals(); err != nil { t.Fatal("Builder.StartAdditionals() =", err) } for _, a := range msg.Additionals { switch a.Body.(type) { case TXTResource: if err := b.TXTResource(a.Header, a.Body.(TXTResource)); err != nil { t.Fatalf("Builder.TXTResource(%#v) = %v", a, err) } case OPTResource: if err := b.OPTResource(a.Header, a.Body.(OPTResource)); err != nil { t.Fatalf("Builder.OPTResource(%#v) = %v", a, err) } } } got, err := b.Finish() if err != nil { t.Fatal("Builder.Finish() =", err) } if !bytes.Equal(got, want) { t.Fatalf("got from Builder.Finish() = %#v\nwant = %#v", got, want) } } func TestResourcePack(t testing.T) { for _, tt := range []struct { m Message err error }{ { Message{ Questions: []Question{ { Name: MustNewName("."), Type: TypeAAAA, Class: ClassINET, }, }, Answers: []Resource{{ResourceHeader{}, nil}}, }, &nestedError{"packing Answer", errNilResouceBody}, }, { Message{ Questions: []Question{ { Name: MustNewName("."), Type: TypeAAAA, Class: ClassINET, }, }, Authorities: []Resource{{ResourceHeader{}, (NSResource)(nil)}}, }, &nestedError{"packing Authority", &nestedError{"ResourceHeader", &nestedError{"Name", errNonCanonicalName}, }, }, }, { Message{ Questions: []Question{ { Name: MustNewName("."), Type: TypeA, Class: ClassINET, }, }, Additionals: []Resource{{ResourceHeader{}, nil}}, }, &nestedError{"packing Additional", errNilResouceBody}, }, } { _, err := tt.m.Pack() if !reflect.DeepEqual(err, tt.err) { t.Errorf("got Message{%v}.Pack() = %v, want %v", tt.m, err, tt.err) } } } func TestResourcePackLength(t testing.T) { r := Resource{ ResourceHeader{ Name: MustNewName("."), Type: TypeA, Class: ClassINET, }, &AResource{[4]byte{127, 0, 0, 2}}, } hb, _, err := r.Header.pack(nil, nil, 0) if err != nil { t.Fatal("ResourceHeader.pack() =", err) } buf := make([]byte, 0, len(hb)) buf, err = r.pack(buf, nil, 0) if err != nil { t.Fatal("Resource.pack() =", err) } var hdr ResourceHeader if _, err := hdr.unpack(buf, 0); err != nil { t.Fatal("ResourceHeader.unpack() =", err) } if got, want := int(hdr.Length), len(buf)-len(hb); got != want { t.Errorf("got hdr.Length = %d, want = %d", got, want) } } func TestOptionPackUnpack(t testing.T) { for _, tt := range []struct { name string w []byte // wire format of m.Additionals m Message dnssecOK bool extRCode RCode }{ { name: "without EDNS(0) options", w: []byte{ 0x00, 0x00, 0x29, 0x10, 0x00, 0xfe, 0x00, 0x80, 0x00, 0x00, 0x00, }, m: Message{ Header: Header{RCode: RCodeFormatError}, Questions: []Question{ { Name: MustNewName("."), Type: TypeA, Class: ClassINET, }, }, Additionals: []Resource{ { mustEDNS0ResourceHeader(4096, 0xfe0\|RCodeFormatError, true), &OPTResource{}, }, }, }, dnssecOK: true, extRCode: 0xfe0 \| RCodeFormatError, }, { name: "with EDNS(0) options", w: []byte{ 0x00, 0x00, 0x29, 0x10, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0x0c, 0x00, 0x0c, 0x00, 0x02, 0x00, 0x00, 0x00, 0x0b, 0x00, 0x02, 0x12, 0x34, }, m: Message{ Header: Header{RCode: RCodeServerFailure}, Questions: []Question{ { Name: MustNewName("."), Type: TypeAAAA, Class: ClassINET, }, }, Additionals: []Resource{ { mustEDNS0ResourceHeader(4096, 0xff0\|RCodeServerFailure, false), &OPTResource{ Options: []Option{ { Code: 12, // see RFC 7828 Data: []byte{0x00, 0x00}, }, { Code: 11, // see RFC 7830 Data: []byte{0x12, 0x34}, }, }, }, }, }, }, dnssecOK: false, extRCode: 0xff0 \| RCodeServerFailure, }, { // Containing multiple OPT resources in a // message is invalid, but it's necessary for // protocol conformance testing. name: "with multiple OPT resources", w: []byte{ 0x00, 0x00, 0x29, 0x10, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00, 0x0b, 0x00, 0x02, 0x12, 0x34, 0x00, 0x00, 0x29, 0x10, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00, 0x0c, 0x00, 0x02, 0x00, 0x00, }, m: Message{ Header: Header{RCode: RCodeNameError}, Questions: []Question{ { Name: MustNewName("."), Type: TypeAAAA, Class: ClassINET, }, }, Additionals: []Resource{ { mustEDNS0ResourceHeader(4096, 0xff0\|RCodeNameError, false), &OPTResource{ Options: []Option{ { Code: 11, // see RFC 7830 Data: []byte{0x12, 0x34}, }, }, }, }, { mustEDNS0ResourceHeader(4096, 0xff0\|RCodeNameError, false), &OPTResource{ Options: []Option{ { Code: 12, // see RFC 7828 Data: []byte{0x00, 0x00}, }, }, }, }, }, }, }, } { w, err := tt.m.Pack() if err != nil { t.Errorf("Message.Pack() for %s = %v", tt.name, err) continue } if !bytes.Equal(w[len(w)-len(tt.w):], tt.w) { t.Errorf("got Message.Pack() for %s = %#v, want %#v", tt.name, w[len(w)-len(tt.w):], tt.w) continue } var m Message if err := m.Unpack(w); err != nil { t.Errorf("Message.Unpack() for %s = %v", tt.name, err) continue } if !reflect.DeepEqual(m.Additionals, tt.m.Additionals) { t.Errorf("got Message.Pack/Unpack() roundtrip for %s = %+v, want %+v", tt.name, m, tt.m) continue } } } func smallTestMsgWithUnknownResource() Message { return Message{ Questions: []Question{}, Answers: []Resource{ { Header: ResourceHeader{ Name: MustNewName("."), Type: privateUseType, Class: ClassINET, TTL: uint32(123), }, Body: &UnknownResource{ // The realType() method is called, when // packing, so Type must match the type // claimed by the Header above. Type: privateUseType, Data: []byte{42, 42, 42, 42}, }, }, }, } } func TestUnknownPackUnpack(t testing.T) { msg := smallTestMsgWithUnknownResource() packed, err := msg.Pack() if err != nil { t.Fatalf("Failed to pack UnknownResource: %v", err) } var receivedMsg Message err = receivedMsg.Unpack(packed) if err != nil { t.Fatalf("Failed to unpack UnknownResource: %v", err) } if len(receivedMsg.Answers) != 1 { t.Fatalf("Got %d answers, wanted 1", len(receivedMsg.Answers)) } unknownResource, ok := receivedMsg.Answers[0].Body.(UnknownResource) if !ok { t.Fatalf("Parsed a %T, wanted an UnknownResource", receivedMsg.Answers[0].Body) } wantBody := msg.Answers[0].Body if !reflect.DeepEqual(wantBody, unknownResource) { t.Fatalf("Unpacked resource does not match: %v vs %v", wantBody, unknownResource) } } func TestParseUnknownResource(t testing.T) { msg := smallTestMsgWithUnknownResource() packed, err := msg.Pack() if err != nil { t.Fatalf("Failed to pack UnknownResource: %v", err) } var p Parser if _, err = p.Start(packed); err != nil { t.Fatalf("Parser failed to start: %s", err) } if _, err = p.AllQuestions(); err != nil { t.Fatalf("Failed to parse questions: %s", err) } parsedHeader, err := p.AnswerHeader() if err != nil { t.Fatalf("Error reading answer header: %s", err) } wantHeader := msg.Answers[0].Header if !reflect.DeepEqual(wantHeader, parsedHeader) { t.Fatalf("Parsed header does not match: %v vs %v", wantHeader, wantHeader) } parsedUnknownResource, err := p.UnknownResource() if err != nil { t.Fatalf("Failed to parse UnknownResource: %s", err) } wantBody := msg.Answers[0].Body if !reflect.DeepEqual(wantBody, &parsedUnknownResource) { t.Fatalf("Parsed resource does not match: %v vs %v", wantBody, &parsedUnknownResource) } // Finish parsing the rest of the message to ensure that // (Parser).UnknownResource() leaves the parser in a consistent state. if _, err = p.AnswerHeader(); err != ErrSectionDone { t.Fatalf("Answer section should be fully parsed") } if _, err = p.AllAuthorities(); err != nil { t.Fatalf("Failed to parse authorities: %s", err) } if _, err = p.AllAdditionals(); err != nil { t.Fatalf("Failed to parse additionals: %s", err) } } // TestGoString tests that Message.GoString produces Go code that compiles to // reproduce the Message. // // This test was produced as follows: // 1. Run (Message).GoString on largeTestMsg(). // 2. Remove "dnsmessage." from the output. // 3. Paste the result in the test to store it in msg. // 4. Also put the original output in the test to store in want. func TestGoString(t testing.T) { msg := Message{Header: Header{ID: 0, Response: true, OpCode: 0, Authoritative: true, Truncated: false, RecursionDesired: false, RecursionAvailable: false, RCode: RCodeSuccess}, Questions: []Question{Question{Name: MustNewName("foo.bar.example.com."), Type: TypeA, Class: ClassINET}}, Answers: []Resource{Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypeA, Class: ClassINET, TTL: 0, Length: 0}, Body: &AResource{A: [4]byte{127, 0, 0, 1}}}, Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypeA, Class: ClassINET, TTL: 0, Length: 0}, Body: &AResource{A: [4]byte{127, 0, 0, 2}}}, Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypeAAAA, Class: ClassINET, TTL: 0, Length: 0}, Body: &AAAAResource{AAAA: [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}}}, Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypeCNAME, Class: ClassINET, TTL: 0, Length: 0}, Body: &CNAMEResource{CNAME: MustNewName("alias.example.com.")}}, Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypeSOA, Class: ClassINET, TTL: 0, Length: 0}, Body: &SOAResource{NS: MustNewName("ns1.example.com."), MBox: MustNewName("mb.example.com."), Serial: 1, Refresh: 2, Retry: 3, Expire: 4, MinTTL: 5}}, Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypePTR, Class: ClassINET, TTL: 0, Length: 0}, Body: &PTRResource{PTR: MustNewName("ptr.example.com.")}}, Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypeMX, Class: ClassINET, TTL: 0, Length: 0}, Body: &MXResource{Pref: 7, MX: MustNewName("mx.example.com.")}}, Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypeSRV, Class: ClassINET, TTL: 0, Length: 0}, Body: &SRVResource{Priority: 8, Weight: 9, Port: 11, Target: MustNewName("srv.example.com.")}}, Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: 65362, Class: ClassINET, TTL: 0, Length: 0}, Body: &UnknownResource{Type: 65362, Data: []byte{42, 0, 43, 44}}}}, Authorities: []Resource{Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypeNS, Class: ClassINET, TTL: 0, Length: 0}, Body: &NSResource{NS: MustNewName("ns1.example.com.")}}, Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypeNS, Class: ClassINET, TTL: 0, Length: 0}, Body: &NSResource{NS: MustNewName("ns2.example.com.")}}}, Additionals: []Resource{Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypeTXT, Class: ClassINET, TTL: 0, Length: 0}, Body: &TXTResource{TXT: []string{"So Long\x2c and Thanks for All the Fish"}}}, Resource{Header: ResourceHeader{Name: MustNewName("foo.bar.example.com."), Type: TypeTXT, Class: ClassINET, TTL: 0, Length: 0}, Body: &TXTResource{TXT: []string{"Hamster Huey and the Gooey Kablooie"}}}, Resource{Header: ResourceHeader{Name: MustNewName("."), Type: TypeOPT, Class: 4096, TTL: 4261412864, Length: 0}, Body: &OPTResource{Options: []Option{Option{Code: 10, Data: []byte{1, 35, 69, 103, 137, 171, 205, 239}}}}}}} if !reflect.DeepEqual(msg, largeTestMsg()) { t.Error("Message.GoString lost information or largeTestMsg changed: msg != largeTestMsg()") } got := msg.GoString() want := `dnsmessage.Message{Header: dnsmessage.Header{ID: 0, Response: true, OpCode: 0, Authoritative: true, Truncated: false, RecursionDesired: false, RecursionAvailable: false, AuthenticData: false, CheckingDisabled: false, RCode: dnsmessage.RCodeSuccess}, Questions: []dnsmessage.Question{dnsmessage.Question{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeA, Class: dnsmessage.ClassINET}}, Answers: []dnsmessage.Resource{dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeA, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.AResource{A: [4]byte{127, 0, 0, 1}}}, dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeA, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.AResource{A: [4]byte{127, 0, 0, 2}}}, dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeAAAA, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.AAAAResource{AAAA: [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}}}, dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeCNAME, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.CNAMEResource{CNAME: dnsmessage.MustNewName("alias.example.com.")}}, dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeSOA, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.SOAResource{NS: dnsmessage.MustNewName("ns1.example.com."), MBox: dnsmessage.MustNewName("mb.example.com."), Serial: 1, Refresh: 2, Retry: 3, Expire: 4, MinTTL: 5}}, dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypePTR, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.PTRResource{PTR: dnsmessage.MustNewName("ptr.example.com.")}}, dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeMX, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.MXResource{Pref: 7, MX: dnsmessage.MustNewName("mx.example.com.")}}, dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeSRV, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.SRVResource{Priority: 8, Weight: 9, Port: 11, Target: dnsmessage.MustNewName("srv.example.com.")}}, dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: 65362, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.UnknownResource{Type: 65362, Data: []byte{42, 0, 43, 44}}}}, Authorities: []dnsmessage.Resource{dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeNS, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.NSResource{NS: dnsmessage.MustNewName("ns1.example.com.")}}, dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeNS, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.NSResource{NS: dnsmessage.MustNewName("ns2.example.com.")}}}, Additionals: []dnsmessage.Resource{dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeTXT, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.TXTResource{TXT: []string{"So Long\x2c and Thanks for All the Fish"}}}, dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("foo.bar.example.com."), Type: dnsmessage.TypeTXT, Class: dnsmessage.ClassINET, TTL: 0, Length: 0}, Body: &dnsmessage.TXTResource{TXT: []string{"Hamster Huey and the Gooey Kablooie"}}}, dnsmessage.Resource{Header: dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName("."), Type: dnsmessage.TypeOPT, Class: 4096, TTL: 4261412864, Length: 0}, Body: &dnsmessage.OPTResource{Options: []dnsmessage.Option{dnsmessage.Option{Code: 10, Data: []byte{1, 35, 69, 103, 137, 171, 205, 239}}}}}}}` if got != want { t.Errorf("got msg1.GoString() = %s\nwant = %s", got, want) } } func benchmarkParsingSetup() ([]byte, error) { name := MustNewName("foo.bar.example.com.") msg := Message{ Header: Header{Response: true, Authoritative: true}, Questions: []Question{ { Name: name, Type: TypeA, Class: ClassINET, }, }, Answers: []Resource{ { ResourceHeader{ Name: name, Class: ClassINET, }, &AResource{[4]byte{}}, }, { ResourceHeader{ Name: name, Class: ClassINET, }, &AAAAResource{[16]byte{}}, }, { ResourceHeader{ Name: name, Class: ClassINET, }, &CNAMEResource{name}, }, { ResourceHeader{ Name: name, Class: ClassINET, }, &NSResource{name}, }, }, } buf, err := msg.Pack() if err != nil { return nil, fmt.Errorf("Message.Pack() = %v", err) } return buf, nil } func benchmarkParsing(tb testing.TB, buf []byte) { var p Parser if _, err := p.Start(buf); err != nil { tb.Fatal("Parser.Start(non-nil) =", err) } for { _, err := p.Question() if err == ErrSectionDone { break } if err != nil { tb.Fatal("Parser.Question() =", err) } } for { h, err := p.AnswerHeader() if err == ErrSectionDone { break } if err != nil { tb.Fatal("Parser.AnswerHeader() =", err) } switch h.Type { case TypeA: if _, err := p.AResource(); err != nil { tb.Fatal("Parser.AResource() =", err) } case TypeAAAA: if _, err := p.AAAAResource(); err != nil { tb.Fatal("Parser.AAAAResource() =", err) } case TypeCNAME: if _, err := p.CNAMEResource(); err != nil { tb.Fatal("Parser.CNAMEResource() =", err) } case TypeNS: if _, err := p.NSResource(); err != nil { tb.Fatal("Parser.NSResource() =", err) } case TypeOPT: if _, err := p.OPTResource(); err != nil { tb.Fatal("Parser.OPTResource() =", err) } default: tb.Fatalf("got unknown type: %T", h) } } } func BenchmarkParsing(b testing.B) { buf, err := benchmarkParsingSetup() if err != nil { b.Fatal(err) } b.ReportAllocs() for i := 0; i < b.N; i++ { benchmarkParsing(b, buf) } } func TestParsingAllocs(t testing.T) { buf, err := benchmarkParsingSetup() if err != nil { t.Fatal(err) } if allocs := testing.AllocsPerRun(100, func() { benchmarkParsing(t, buf) }); allocs > 0.5 { t.Errorf("allocations during parsing: got = %f, want ~0", allocs) } } func benchmarkBuildingSetup() (Name, []byte) { name := MustNewName("foo.bar.example.com.") buf := make([]byte, 0, packStartingCap) return name, buf } func benchmarkBuilding(tb testing.TB, name Name, buf []byte) { bld := NewBuilder(buf, Header{Response: true, Authoritative: true}) if err := bld.StartQuestions(); err != nil { tb.Fatal("Builder.StartQuestions() =", err) } q := Question{ Name: name, Type: TypeA, Class: ClassINET, } if err := bld.Question(q); err != nil { tb.Fatalf("Builder.Question(%+v) = %v", q, err) } hdr := ResourceHeader{ Name: name, Class: ClassINET, } if err := bld.StartAnswers(); err != nil { tb.Fatal("Builder.StartQuestions() =", err) } ar := AResource{[4]byte{}} if err := bld.AResource(hdr, ar); err != nil { tb.Fatalf("Builder.AResource(%+v, %+v) = %v", hdr, ar, err) } aaar := AAAAResource{[16]byte{}} if err := bld.AAAAResource(hdr, aaar); err != nil { tb.Fatalf("Builder.AAAAResource(%+v, %+v) = %v", hdr, aaar, err) } cnr := CNAMEResource{name} if err := bld.CNAMEResource(hdr, cnr); err != nil { tb.Fatalf("Builder.CNAMEResource(%+v, %+v) = %v", hdr, cnr, err) } nsr := NSResource{name} if err := bld.NSResource(hdr, nsr); err != nil { tb.Fatalf("Builder.NSResource(%+v, %+v) = %v", hdr, nsr, err) } extrc := 0xfe0 \| RCodeNotImplemented if err := (&hdr).SetEDNS0(4096, extrc, true); err != nil { tb.Fatalf("ResourceHeader.SetEDNS0(4096, %#x, true) = %v", extrc, err) } optr := OPTResource{} if err := bld.OPTResource(hdr, optr); err != nil { tb.Fatalf("Builder.OPTResource(%+v, %+v) = %v", hdr, optr, err) } if _, err := bld.Finish(); err != nil { tb.Fatal("Builder.Finish() =", err) } } func BenchmarkBuilding(b testing.B) { name, buf := benchmarkBuildingSetup() b.ReportAllocs() for i := 0; i < b.N; i++ { benchmarkBuilding(b, name, buf) } } func TestBuildingAllocs(t testing.T) { name, buf := benchmarkBuildingSetup() if allocs := testing.AllocsPerRun(100, func() { benchmarkBuilding(t, name, buf) }); allocs > 0.5 { t.Errorf("allocations during building: got = %f, want ~0", allocs) } } func smallTestMsg() Message { name := MustNewName("example.com.") return Message{ Header: Header{Response: true, Authoritative: true}, Questions: []Question{ { Name: name, Type: TypeA, Class: ClassINET, }, }, Answers: []Resource{ { ResourceHeader{ Name: name, Type: TypeA, Class: ClassINET, }, &AResource{[4]byte{127, 0, 0, 1}}, }, }, Authorities: []Resource{ { ResourceHeader{ Name: name, Type: TypeA, Class: ClassINET, }, &AResource{[4]byte{127, 0, 0, 1}}, }, }, Additionals: []Resource{ { ResourceHeader{ Name: name, Type: TypeA, Class: ClassINET, }, &AResource{[4]byte{127, 0, 0, 1}}, }, }, } } func BenchmarkPack(b testing.B) { msg := largeTestMsg() b.ReportAllocs() for i := 0; i < b.N; i++ { if _, err := msg.Pack(); err != nil { b.Fatal("Message.Pack() =", err) } } } func BenchmarkAppendPack(b testing.B) { msg := largeTestMsg() buf := make([]byte, 0, packStartingCap) b.ReportAllocs() for i := 0; i < b.N; i++ { if _, err := msg.AppendPack(buf[:0]); err != nil { b.Fatal("Message.AppendPack() = ", err) } } } func largeTestMsg() Message { name := MustNewName("foo.bar.example.com.") return Message{ Header: Header{Response: true, Authoritative: true}, Questions: []Question{ { Name: name, Type: TypeA, Class: ClassINET, }, }, Answers: []Resource{ { ResourceHeader{ Name: name, Type: TypeA, Class: ClassINET, }, &AResource{[4]byte{127, 0, 0, 1}}, }, { ResourceHeader{ Name: name, Type: TypeA, Class: ClassINET, }, &AResource{[4]byte{127, 0, 0, 2}}, }, { ResourceHeader{ Name: name, Type: TypeAAAA, Class: ClassINET, }, &AAAAResource{[16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}}, }, { ResourceHeader{ Name: name, Type: TypeCNAME, Class: ClassINET, }, &CNAMEResource{MustNewName("alias.example.com.")}, }, { ResourceHeader{ Name: name, Type: TypeSOA, Class: ClassINET, }, &SOAResource{ NS: MustNewName("ns1.example.com."), MBox: MustNewName("mb.example.com."), Serial: 1, Refresh: 2, Retry: 3, Expire: 4, MinTTL: 5, }, }, { ResourceHeader{ Name: name, Type: TypePTR, Class: ClassINET, }, &PTRResource{MustNewName("ptr.example.com.")}, }, { ResourceHeader{ Name: name, Type: TypeMX, Class: ClassINET, }, &MXResource{ 7, MustNewName("mx.example.com."), }, }, { ResourceHeader{ Name: name, Type: TypeSRV, Class: ClassINET, }, &SRVResource{ 8, 9, 11, MustNewName("srv.example.com."), }, }, { ResourceHeader{ Name: name, Type: privateUseType, Class: ClassINET, }, &UnknownResource{ Type: privateUseType, Data: []byte{42, 0, 43, 44}, }, }, }, Authorities: []Resource{ { ResourceHeader{ Name: name, Type: TypeNS, Class: ClassINET, }, &NSResource{MustNewName("ns1.example.com.")}, }, { ResourceHeader{ Name: name, Type: TypeNS, Class: ClassINET, }, &NSResource{MustNewName("ns2.example.com.")}, }, }, Additionals: []Resource{ { ResourceHeader{ Name: name, Type: TypeTXT, Class: ClassINET, }, &TXTResource{[]string{"So Long, and Thanks for All the Fish"}}, }, { ResourceHeader{ Name: name, Type: TypeTXT, Class: ClassINET, }, &TXTResource{[]string{"Hamster Huey and the Gooey Kablooie"}}, }, { mustEDNS0ResourceHeader(4096, 0xfe0\|RCodeSuccess, false), &OPTResource{ Options: []Option{ { Code: 10, // see RFC 7873 Data: []byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef}, }, }, }, }, }, } } // This package is imported by the standard library net package // and therefore must not use fmt. We'll catch a mistake when vendored // into the standard library, but this test catches the mistake earlier. func TestNoFmt(t testing.T) { files, err := filepath.Glob(".go") if err != nil { t.Fatal(err) } for _, file := range files { if strings.HasSuffix(file, "_test.go") { continue } // Could use something complex like go/build or x/tools/go/packages, // but there's no reason for "fmt" to appear (in quotes) in the source // otherwise, so just use a simple substring search. data, err := os.ReadFile(file) if err != nil { t.Fatal(err) } if bytes.Contains(data, []byte(`"fmt"`)) { t.Errorf(`%s: cannot import "fmt"`, file) } } } func FuzzUnpackPack(f testing.F) { for _, msg := range []Message{smallTestMsg(), largeTestMsg()} { bytes, _ := msg.Pack() f.Add(bytes) } f.Fuzz(func(t testing.T, msg []byte) { var m Message if err := m.Unpack(msg); err != nil { return } msgPacked, err := m.Pack() if err != nil { t.Fatalf("failed to pack message that was successfully unpacked: %v", err) } var m2 Message if err := m2.Unpack(msgPacked); err != nil { t.Fatalf("failed to unpack message that was succesfully packed: %v", err) } if !reflect.DeepEqual(m, m2) { t.Fatal("unpack(msg) is not deep equal to unpack(pack(unpack(msg)))") } }) } func TestParseResourceHeaderMultipleTimes(t testing.T) { msg := Message{ Header: Header{Response: true, Authoritative: true}, Answers: []Resource{ { ResourceHeader{ Name: MustNewName("go.dev."), Type: TypeA, Class: ClassINET, }, &AResource{[4]byte{127, 0, 0, 1}}, }, }, Authorities: []Resource{ { ResourceHeader{ Name: MustNewName("go.dev."), Type: TypeA, Class: ClassINET, }, &AResource{[4]byte{127, 0, 0, 1}}, }, }, } raw, err := msg.Pack() if err != nil { t.Fatal(err) } var p Parser if _, err := p.Start(raw); err != nil { t.Fatal(err) } if err := p.SkipAllQuestions(); err != nil { t.Fatal(err) } hdr1, err := p.AnswerHeader() if err != nil { t.Fatal(err) } hdr2, err := p.AnswerHeader() if err != nil { t.Fatal(err) } if hdr1 != hdr2 { t.Fatal("AnswerHeader called multiple times without parsing the RData returned different headers") } if _, err := p.AResource(); err != nil { t.Fatal(err) } if _, err := p.AnswerHeader(); err != ErrSectionDone { t.Fatalf("unexpected error: %v, want: %v", err, ErrSectionDone) } hdr3, err := p.AuthorityHeader() if err != nil { t.Fatal(err) } hdr4, err := p.AuthorityHeader() if err != nil { t.Fatal(err) } if hdr3 != hdr4 { t.Fatal("AuthorityHeader called multiple times without parsing the RData returned different headers") } if _, err := p.AResource(); err != nil { t.Fatal(err) } if _, err := p.AuthorityHeader(); err != ErrSectionDone { t.Fatalf("unexpected error: %v, want: %v", err, ErrSectionDone) } } func TestParseDifferentResourceHeadersWithoutParsingRData(t testing.T) { msg := smallTestMsg() raw, err := msg.Pack() if err != nil { t.Fatal(err) } var p Parser if _, err := p.Start(raw); err != nil { t.Fatal(err) } if err := p.SkipAllQuestions(); err != nil { t.Fatal(err) } if _, err := p.AnswerHeader(); err != nil { t.Fatal(err) } if _, err := p.AdditionalHeader(); err == nil { t.Errorf("p.AdditionalHeader() unexpected success") } if _, err := p.AuthorityHeader(); err == nil { t.Errorf("p.AuthorityHeader() unexpected success") } } func TestParseWrongSection(t testing.T) { msg := smallTestMsg() raw, err := msg.Pack() if err != nil { t.Fatal(err) } var p Parser if _, err := p.Start(raw); err != nil { t.Fatal(err) } if err := p.SkipAllQuestions(); err != nil { t.Fatalf("p.SkipAllQuestions() = %v", err) } if _, err := p.AnswerHeader(); err != nil { t.Fatalf("p.AnswerHeader() = %v", err) } if _, err := p.AuthorityHeader(); err == nil { t.Fatalf("p.AuthorityHeader(): unexpected success in Answer section") } if err := p.SkipAuthority(); err == nil { t.Fatalf("p.SkipAuthority(): unexpected success in Answer section") } if err := p.SkipAllAuthorities(); err == nil { t.Fatalf("p.SkipAllAuthorities(): unexpected success in Answer section") } } func TestBuilderNameCompressionWithNonZeroedName(t testing.T) { b := NewBuilder(nil, Header{}) b.EnableCompression() if err := b.StartQuestions(); err != nil { t.Fatalf("b.StartQuestions() unexpected error: %v", err) } name := MustNewName("go.dev.") if err := b.Question(Question{Name: name}); err != nil { t.Fatalf("b.Question() unexpected error: %v", err) } // Character that is not part of the name (name.Data[:name.Length]), // shouldn't affect the compression algorithm. name.Data[name.Length] = '1' if err := b.Question(Question{Name: name}); err != nil { t.Fatalf("b.Question() unexpected error: %v", err) } msg, err := b.Finish() if err != nil { t.Fatalf("b.Finish() unexpected error: %v", err) } expect := []byte{ 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, // header 2, 'g', 'o', 3, 'd', 'e', 'v', 0, 0, 0, 0, 0, // question 1 0xC0, 12, 0, 0, 0, 0, // question 2 } if !bytes.Equal(msg, expect) { t.Fatalf("b.Finish() = %v, want: %v", msg, expect) } } func TestBuilderCompressionInAppendMode(t testing.T) { maxPtr := int(^uint16(0) >> 2) b := NewBuilder(make([]byte, maxPtr, maxPtr+512), Header{}) b.EnableCompression() if err := b.StartQuestions(); err != nil { t.Fatalf("b.StartQuestions() unexpected error: %v", err) } if err := b.Question(Question{Name: MustNewName("go.dev.")}); err != nil { t.Fatalf("b.Question() unexpected error: %v", err) } if err := b.Question(Question{Name: MustNewName("go.dev.")}); err != nil { t.Fatalf("b.Question() unexpected error: %v", err) } msg, err := b.Finish() if err != nil { t.Fatalf("b.Finish() unexpected error: %v", err) } expect := []byte{ 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, // header 2, 'g', 'o', 3, 'd', 'e', 'v', 0, 0, 0, 0, 0, // question 1 0xC0, 12, 0, 0, 0, 0, // question 2 } if !bytes.Equal(msg[maxPtr:], expect) { t.Fatalf("msg[maxPtr:] = %v, want: %v", msg[maxPtr:], expect) } }	50.56 KB	2025-05-25 12:27

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