dns

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 Go to latest Published: Feb 24, 2021 License: BSD-3-Clause Imports: 27 Imported by: 4

README

CodeQL go builder verifier

Alternative (slimmer) client approach to miekg/dns

Less is more.

Complete and usable DNS library. All Resource Records are supported, including the DNSSEC types. It follows a lean and mean philosophy. If there is stuff you should know as a DNS programmer there isn't a convenience function for it.

Server side and client side programming is NOT supported

This repository tries to keep the "master" branch as sane as possible and at the bleeding edge of standards, avoiding breaking changes whoever responsible.

Goals

  • Slim;

Users

A not-so-up-to-date-list-that-may-be-actually-current:

Send pull request if you want to be listed here.

Features

  • DNSSEC: signing, validating and key generation for DSA, RSA, ECDSA and Ed25519
  • EDNS0, NSID, Cookies
  • AXFR/IXFR
  • TSIG, SIG(0)
  • DNS name compression

Have fun!

AZ-X 2021

Building

This library uses Go modules and uses semantic versioning. Building is done with the go tool, so the following should work:

go get github.com/AZ-X/dns
go build github.com/AZ-X/dns

Documentation

Overview

Package dns implements a full featured interface to the Domain Name System. Both server- and client-side programming is supported. The package allows complete control over what is sent out to the DNS. The API follows the less-is-more principle, by presenting a small, clean interface.

It supports (asynchronous) querying/replying, incoming/outgoing zone transfers, TSIG, EDNS0, dynamic updates, notifies and DNSSEC validation/signing.

Note that domain names MUST be fully qualified before sending them, unqualified names in a message will result in a packing failure.

Resource records are native types. They are not stored in wire format. Basic usage pattern for creating a new resource record: 

r := new(dns.MX)
r.Hdr = dns.RR_Header{Name: "miek.nl.", Rrtype: dns.TypeMX, Class: dns.ClassINET, Ttl: 3600}
r.Preference = 10
r.Mx = "mx.miek.nl."

Or directly from a string: 

mx, err := dns.NewRR("miek.nl. 3600 IN MX 10 mx.miek.nl.")

Or when the default origin (.) and TTL (3600) and class (IN) suit you: 

mx, err := dns.NewRR("miek.nl MX 10 mx.miek.nl")

Or even: 

mx, err := dns.NewRR("$ORIGIN nl.\nmiek 1H IN MX 10 mx.miek")

In the DNS messages are exchanged, these messages contain resource records (sets). Use pattern for creating a message: 

m := new(dns.Msg)
m.SetQuestion("miek.nl.", dns.TypeMX)

Or when not certain if the domain name is fully qualified: 

m.SetQuestion(dns.Fqdn("miek.nl"), dns.TypeMX)

The message m is now a message with the question section set to ask the MX records for the miek.nl. zone.

The following is slightly more verbose, but more flexible: 

m1 := new(dns.Msg)
m1.Id = dns.Id()
m1.RecursionDesired = true
m1.Question = make([]dns.Question, 1)
m1.Question[0] = dns.Question{"miek.nl.", dns.TypeMX, dns.ClassINET}

After creating a message it can be sent. Basic use pattern for synchronous querying the DNS at a server configured on 127.0.0.1 and port 53: 

c := new(dns.Client)
in, rtt, err := c.Exchange(m1, "127.0.0.1:53")

Suppressing multiple outstanding queries (with the same question, type and class) is as easy as setting: 

c.SingleInflight = true

More advanced options are available using a net.Dialer and the corresponding API. For example it is possible to set a timeout, or to specify a source IP address and port to use for the connection: 

c := new(dns.Client)
laddr := net.UDPAddr{
	IP: net.ParseIP("[::1]"),
	Port: 12345,
	Zone: "",
}
c.Dialer := &net.Dialer{
	Timeout: 200 * time.Millisecond,
	LocalAddr: &laddr,
}
in, rtt, err := c.Exchange(m1, "8.8.8.8:53")

If these "advanced" features are not needed, a simple UDP query can be sent, with: 

in, err := dns.Exchange(m1, "127.0.0.1:53")

When this functions returns you will get DNS message. A DNS message consists out of four sections. The question section: in.Question, the answer section: in.Answer, the authority section: in.Ns and the additional section: in.Extra.

Each of these sections (except the Question section) contain a []RR. Basic use pattern for accessing the rdata of a TXT RR as the first RR in the Answer section: 

if t, ok := in.Answer[0].(*dns.TXT); ok {
	// do something with t.Txt
}

Domain Name and TXT Character String Representations

Both domain names and TXT character strings are converted to presentation form both when unpacked and when converted to strings.

For TXT character strings, tabs, carriage returns and line feeds will be converted to \t, \r and \n respectively. Back slashes and quotations marks will be escaped. Bytes below 32 and above 127 will be converted to \DDD form.

For domain names, in addition to the above rules brackets, periods, spaces, semicolons and the at symbol are escaped.

DNSSEC

DNSSEC (DNS Security Extension) adds a layer of security to the DNS. It uses public key cryptography to sign resource records. The public keys are stored in DNSKEY records and the signatures in RRSIG records.

Requesting DNSSEC information for a zone is done by adding the DO (DNSSEC OK) bit to a request. 

m := new(dns.Msg)
m.SetEdns0(4096, true)

Signature generation, signature verification and key generation are all supported.

DYNAMIC UPDATES

Dynamic updates reuses the DNS message format, but renames three of the sections. Question is Zone, Answer is Prerequisite, Authority is Update, only the Additional is not renamed. See RFC 2136 for the gory details.

You can set a rather complex set of rules for the existence of absence of certain resource records or names in a zone to specify if resource records should be added or removed. The table from RFC 2136 supplemented with the Go DNS function shows which functions exist to specify the prerequisites. 

3.2.4 - Table Of Metavalues Used In Prerequisite Section

 CLASS    TYPE     RDATA    Meaning                    Function
 --------------------------------------------------------------
 ANY      ANY      empty    Name is in use             dns.NameUsed
 ANY      rrset    empty    RRset exists (value indep) dns.RRsetUsed
 NONE     ANY      empty    Name is not in use         dns.NameNotUsed
 NONE     rrset    empty    RRset does not exist       dns.RRsetNotUsed
 zone     rrset    rr       RRset exists (value dep)   dns.Used

The prerequisite section can also be left empty. If you have decided on the prerequisites you can tell what RRs should be added or deleted. The next table shows the options you have and what functions to call. 

3.4.2.6 - Table Of Metavalues Used In Update Section

 CLASS    TYPE     RDATA    Meaning                     Function
 ---------------------------------------------------------------
 ANY      ANY      empty    Delete all RRsets from name dns.RemoveName
 ANY      rrset    empty    Delete an RRset             dns.RemoveRRset
 NONE     rrset    rr       Delete an RR from RRset     dns.Remove
 zone     rrset    rr       Add to an RRset             dns.Insert

TRANSACTION SIGNATURE

An TSIG or transaction signature adds a HMAC TSIG record to each message sent. The supported algorithms include: HmacMD5, HmacSHA1, HmacSHA256 and HmacSHA512.

Basic use pattern when querying with a TSIG name "axfr." (note that these key names must be fully qualified - as they are domain names) and the base64 secret "so6ZGir4GPAqINNh9U5c3A==":

If an incoming message contains a TSIG record it MUST be the last record in the additional section (RFC2845 3.2). This means that you should make the call to SetTsig last, right before executing the query. If you make any changes to the RRset after calling SetTsig() the signature will be incorrect. 

c := new(dns.Client)
c.TsigSecret = map[string]string{"axfr.": "so6ZGir4GPAqINNh9U5c3A=="}
m := new(dns.Msg)
m.SetQuestion("miek.nl.", dns.TypeMX)
m.SetTsig("axfr.", dns.HmacMD5, 300, time.Now().Unix())
...
// When sending the TSIG RR is calculated and filled in before sending

When requesting an zone transfer (almost all TSIG usage is when requesting zone transfers), with TSIG, this is the basic use pattern. In this example we request an AXFR for miek.nl. with TSIG key named "axfr." and secret "so6ZGir4GPAqINNh9U5c3A==" and using the server 176.58.119.54: 

t := new(dns.Transfer)
m := new(dns.Msg)
t.TsigSecret = map[string]string{"axfr.": "so6ZGir4GPAqINNh9U5c3A=="}
m.SetAxfr("miek.nl.")
m.SetTsig("axfr.", dns.HmacMD5, 300, time.Now().Unix())
c, err := t.In(m, "176.58.119.54:53")
for r := range c { ... }

You can now read the records from the transfer as they come in. Each envelope is checked with TSIG. If something is not correct an error is returned.

A custom TSIG implementation can be used. This requires additional code to perform any session establishment and signature generation/verification. The client must be configured with an implementation of the TsigProvider interface: 

type Provider struct{}

func (*Provider) Generate(msg []byte, tsig *dns.TSIG) ([]byte, error) {
	// Use tsig.Hdr.Name and tsig.Algorithm in your code to
	// generate the MAC using msg as the payload.
}

func (*Provider) Verify(msg []byte, tsig *dns.TSIG) error {
	// Use tsig.Hdr.Name and tsig.Algorithm in your code to verify
	// that msg matches the value in tsig.MAC.
}

c := new(dns.Client)
c.TsigProvider = new(Provider)
m := new(dns.Msg)
m.SetQuestion("miek.nl.", dns.TypeMX)
m.SetTsig(keyname, dns.HmacSHA1, 300, time.Now().Unix())
...
// TSIG RR is calculated by calling your Generate method

Basic use pattern validating and replying to a message that has TSIG set. 

server := &dns.Server{Addr: ":53", Net: "udp"}
server.TsigSecret = map[string]string{"axfr.": "so6ZGir4GPAqINNh9U5c3A=="}
go server.ListenAndServe()
dns.HandleFunc(".", handleRequest)

func handleRequest(w dns.ResponseWriter, r *dns.Msg) {
	m := new(dns.Msg)
	m.SetReply(r)
	if r.IsTsig() != nil {
		if w.TsigStatus() == nil {
			// *Msg r has an TSIG record and it was validated
			m.SetTsig("axfr.", dns.HmacMD5, 300, time.Now().Unix())
		} else {
			// *Msg r has an TSIG records and it was not validated
		}
	}
	w.WriteMsg(m)
}

PRIVATE RRS

RFC 6895 sets aside a range of type codes for private use. This range is 65,280 - 65,534 (0xFF00 - 0xFFFE). When experimenting with new Resource Records these can be used, before requesting an official type code from IANA.

See https://miek.nl/2014/september/21/idn-and-private-rr-in-go-dns/ for more information.

EDNS0

EDNS0 is an extension mechanism for the DNS defined in RFC 2671 and updated by RFC 6891. It defines an new RR type, the OPT RR, which is then completely abused.

Basic use pattern for creating an (empty) OPT RR: 

o := new(dns.OPT)
o.Hdr.Name = "." // MUST be the root zone, per definition.
o.Hdr.Rrtype = dns.TypeOPT

The rdata of an OPT RR consists out of a slice of EDNS0 (RFC 6891) interfaces. Currently only a few have been standardized: EDNS0_NSID (RFC 5001) and EDNS0_SUBNET (RFC 7871). Note that these options may be combined in an OPT RR. Basic use pattern for a server to check if (and which) options are set: 

// o is a dns.OPT
for _, s := range o.Option {
	switch e := s.(type) {
	case *dns.EDNS0_NSID:
		// do stuff with e.Nsid
	case *dns.EDNS0_SUBNET:
		// access e.Family, e.Address, etc.
	}
}

SIG(0)

From RFC 2931: 

SIG(0) provides protection for DNS transactions and requests ....
... protection for glue records, DNS requests, protection for message headers
on requests and responses, and protection of the overall integrity of a response.

It works like TSIG, except that SIG(0) uses public key cryptography, instead of the shared secret approach in TSIG. Supported algorithms: ECDSAP256SHA256, ECDSAP384SHA384, RSASHA1, RSASHA256 and RSASHA512.

Signing subsequent messages in multi-message sessions is not implemented.

Index

Constants

View Source 
const (

	// DefaultMsgSize is the standard default for messages larger than 512 bytes.
	DefaultMsgSize = 4096
	// MinMsgSize is the minimal size of a DNS packet.
	MinMsgSize = 512
	// MaxMsgSize is the largest possible DNS packet.
	MaxMsgSize = 65535
)
View Source 
const (
	RSAMD5 uint8
	DH
	DSA

	RSASHA1
	DSANSEC3SHA1
	RSASHA1NSEC3SHA1
	RSASHA256

	RSASHA512

	ECCGOST
	ECDSAP256SHA256
	ECDSAP384SHA384
	ED25519
	ED448
	INDIRECT   uint8 = 252
	PRIVATEDNS uint8 = 253 // Private (experimental keys)
	PRIVATEOID uint8 = 254
)

DNSSEC encryption algorithm codes.

View Source 
const (
	SHA1   uint8 // RFC 4034
	SHA256       // RFC 4509
	GOST94       // RFC 5933
	SHA384       // Experimental
	SHA512       // Experimental
)

DNSSEC hashing algorithm codes.

View Source 
const (
	SEP    = 1
	REVOKE = 1 << 7
	ZONE   = 1 << 8
)

DNSKEY flag values.

View Source 
const (
	EDNS0LLQ          = 0x1    // long lived queries: http://tools.ietf.org/html/draft-sekar-dns-llq-01
	EDNS0UL           = 0x2    // update lease draft: http://files.dns-sd.org/draft-sekar-dns-ul.txt
	EDNS0NSID         = 0x3    // nsid (See RFC 5001)
	EDNS0DAU          = 0x5    // DNSSEC Algorithm Understood
	EDNS0DHU          = 0x6    // DS Hash Understood
	EDNS0N3U          = 0x7    // NSEC3 Hash Understood
	EDNS0SUBNET       = 0x8    // client-subnet (See RFC 7871)
	EDNS0EXPIRE       = 0x9    // EDNS0 expire
	EDNS0COOKIE       = 0xa    // EDNS0 Cookie
	EDNS0TCPKEEPALIVE = 0xb    // EDNS0 tcp keep alive (See RFC 7828)
	EDNS0PADDING      = 0xc    // EDNS0 padding (See RFC 7830)
	EDNS0LOCALSTART   = 0xFDE9 // Beginning of range reserved for local/experimental use (See RFC 6891)
	EDNS0LOCALEND     = 0xFFFE // End of range reserved for local/experimental use (See RFC 6891)

)

EDNS0 Option codes.

View Source 
const (
	HmacSHA1   = "hmac-sha1."
	HmacSHA224 = "hmac-sha224."
	HmacSHA256 = "hmac-sha256."
	HmacSHA384 = "hmac-sha384."
	HmacSHA512 = "hmac-sha512."

	HmacMD5 = "hmac-md5.sig-alg.reg.int." // Deprecated: HmacMD5 is no longer supported.
)

HMAC hashing codes. These are transmitted as domain names.

View Source 
const (
	TypeNone       uint16 = 0
	TypeA          uint16 = 1
	TypeNS         uint16 = 2
	TypeMD         uint16 = 3
	TypeMF         uint16 = 4
	TypeCNAME      uint16 = 5
	TypeSOA        uint16 = 6
	TypeMB         uint16 = 7
	TypeMG         uint16 = 8
	TypeMR         uint16 = 9
	TypeNULL       uint16 = 10
	TypePTR        uint16 = 12
	TypeHINFO      uint16 = 13
	TypeMINFO      uint16 = 14
	TypeMX         uint16 = 15
	TypeTXT        uint16 = 16
	TypeRP         uint16 = 17
	TypeAFSDB      uint16 = 18
	TypeX25        uint16 = 19
	TypeISDN       uint16 = 20
	TypeRT         uint16 = 21
	TypeNSAPPTR    uint16 = 23
	TypeSIG        uint16 = 24
	TypeKEY        uint16 = 25
	TypePX         uint16 = 26
	TypeGPOS       uint16 = 27
	TypeAAAA       uint16 = 28
	TypeLOC        uint16 = 29
	TypeNXT        uint16 = 30
	TypeEID        uint16 = 31
	TypeNIMLOC     uint16 = 32
	TypeSRV        uint16 = 33
	TypeATMA       uint16 = 34
	TypeNAPTR      uint16 = 35
	TypeKX         uint16 = 36
	TypeCERT       uint16 = 37
	TypeDNAME      uint16 = 39
	TypeSINK       uint16 = 40 // Donald E. Eastlake
	TypeOPT        uint16 = 41 // EDNS
	TypeAPL        uint16 = 42
	TypeDS         uint16 = 43
	TypeSSHFP      uint16 = 44
	TypeIPSECKEY   uint16 = 45
	TypeRRSIG      uint16 = 46
	TypeNSEC       uint16 = 47
	TypeDNSKEY     uint16 = 48
	TypeDHCID      uint16 = 49
	TypeNSEC3      uint16 = 50
	TypeNSEC3PARAM uint16 = 51
	TypeTLSA       uint16 = 52
	TypeSMIMEA     uint16 = 53
	TypeHIP        uint16 = 55
	TypeNINFO      uint16 = 56
	TypeRKEY       uint16 = 57
	TypeTALINK     uint16 = 58
	TypeCDS        uint16 = 59
	TypeCDNSKEY    uint16 = 60
	TypeOPENPGPKEY uint16 = 61
	TypeCSYNC      uint16 = 62
	TypeSVCB       uint16 = 64
	TypeHTTPS      uint16 = 65
	TypeSPF        uint16 = 99
	TypeUINFO      uint16 = 100
	TypeUID        uint16 = 101
	TypeGID        uint16 = 102
	TypeUNSPEC     uint16 = 103
	TypeNID        uint16 = 104
	TypeL32        uint16 = 105
	TypeL64        uint16 = 106
	TypeLP         uint16 = 107
	TypeEUI48      uint16 = 108
	TypeEUI64      uint16 = 109
	TypeURI        uint16 = 256
	TypeCAA        uint16 = 257
	TypeAVC        uint16 = 258

	TypeTKEY uint16 = 249
	TypeTSIG uint16 = 250

	// valid Question.Qtype only
	TypeIXFR  uint16 = 251
	TypeAXFR  uint16 = 252
	TypeMAILB uint16 = 253
	TypeMAILA uint16 = 254
	TypeANY   uint16 = 255

	TypeTA       uint16 = 32768
	TypeDLV      uint16 = 32769
	TypeReserved uint16 = 65535

	// valid Question.Qclass
	ClassINET   = 1
	ClassCHAOS  = 3
	ClassHESIOD = 4
	ClassNONE   = 254
	ClassANY    = 255

	// Message Response Codes, see https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml
	RcodeSuccess        = 0  // NoError   - No Error                          [DNS]
	RcodeFormatError    = 1  // FormErr   - Format Error                      [DNS]
	RcodeServerFailure  = 2  // ServFail  - Server Failure                    [DNS]
	RcodeNameError      = 3  // NXDomain  - Non-Existent Domain               [DNS]
	RcodeNotImplemented = 4  // NotImp    - Not Implemented                   [DNS]
	RcodeRefused        = 5  // Refused   - Query Refused                     [DNS]
	RcodeYXDomain       = 6  // YXDomain  - Name Exists when it should not    [DNS Update]
	RcodeYXRrset        = 7  // YXRRSet   - RR Set Exists when it should not  [DNS Update]
	RcodeNXRrset        = 8  // NXRRSet   - RR Set that should exist does not [DNS Update]
	RcodeNotAuth        = 9  // NotAuth   - Server Not Authoritative for zone [DNS Update]
	RcodeNotZone        = 10 // NotZone   - Name not contained in zone        [DNS Update/TSIG]
	RcodeBadSig         = 16 // BADSIG    - TSIG Signature Failure            [TSIG]
	RcodeBadVers        = 16 // BADVERS   - Bad OPT Version                   [EDNS0]
	RcodeBadKey         = 17 // BADKEY    - Key not recognized                [TSIG]
	RcodeBadTime        = 18 // BADTIME   - Signature out of time window      [TSIG]
	RcodeBadMode        = 19 // BADMODE   - Bad TKEY Mode                     [TKEY]
	RcodeBadName        = 20 // BADNAME   - Duplicate key name                [TKEY]
	RcodeBadAlg         = 21 // BADALG    - Algorithm not supported           [TKEY]
	RcodeBadTrunc       = 22 // BADTRUNC  - Bad Truncation                    [TSIG]
	RcodeBadCookie      = 23 // BADCOOKIE - Bad/missing Server Cookie         [DNS Cookies]

	// Message Opcodes. There is no 3.
	OpcodeQuery  = 0
	OpcodeIQuery = 1
	OpcodeStatus = 2
	OpcodeNotify = 4
	OpcodeUpdate = 5
)

Wire constants and supported types.

View Source 
const (
	LOC_EQUATOR       = 1 << 31 // RFC 1876, Section 2.
	LOC_PRIMEMERIDIAN = 1 << 31 // RFC 1876, Section 2.
	LOC_HOURS         = 60 * 1000
	LOC_DEGREES       = 60 * LOC_HOURS
	LOC_ALTITUDEBASE  = 100000
)

Various constants used in the LOC RR. See RFC 1887.

View Source 
const (
	CertPKIX = 1 + iota
	CertSPKI
	CertPGP
	CertIPIX
	CertISPKI
	CertIPGP
	CertACPKIX
	CertIACPKIX
	CertURI = 253
	CertOID = 254
)

Different Certificate Types, see RFC 4398, Section 2.1

Variables

View Source 
var (
	ErrAlg           error = &Error{err: "bad algorithm"}                  // ErrAlg indicates an error with the (DNSSEC) algorithm.
	ErrAuth          error = &Error{err: "bad authentication"}             // ErrAuth indicates an error in the TSIG authentication.
	ErrBuf           error = &Error{err: "buffer size too small"}          // ErrBuf indicates that the buffer used is too small for the message.
	ErrConnEmpty     error = &Error{err: "conn has no connection"}         // ErrConnEmpty indicates a connection is being used before it is initialized.
	ErrExtendedRcode error = &Error{err: "bad extended rcode"}             // ErrExtendedRcode ...
	ErrFqdn          error = &Error{err: "domain must be fully qualified"} // ErrFqdn indicates that a domain name does not have a closing dot.
	ErrId            error = &Error{err: "id mismatch"}                    // ErrId indicates there is a mismatch with the message's ID.
	ErrKeyAlg        error = &Error{err: "bad key algorithm"}              // ErrKeyAlg indicates that the algorithm in the key is not valid.
	ErrKey           error = &Error{err: "bad key"}
	ErrKeySize       error = &Error{err: "bad key size"}
	ErrLongDomain    error = &Error{err: fmt.Sprintf("domain name exceeded %d wire-format octets", maxDomainNameWireOctets)}
	ErrNoSig         error = &Error{err: "no signature found"}
	ErrPrivKey       error = &Error{err: "bad private key"}
	ErrRcode         error = &Error{err: "bad rcode"}
	ErrRdata         error = &Error{err: "bad rdata"}
	ErrRRset         error = &Error{err: "bad rrset"}
	ErrSecret        error = &Error{err: "no secrets defined"}
	ErrShortRead     error = &Error{err: "short read"}
	ErrSig           error = &Error{err: "bad signature"} // ErrSig indicates that a signature can not be cryptographically validated.
	ErrSoa           error = &Error{err: "no SOA"}        // ErrSOA indicates that no SOA RR was seen when doing zone transfers.
	ErrTime          error = &Error{err: "bad time"}      // ErrTime indicates a timing error in TSIG authentication.
)

Errors defined in this package.

View Source 
var AlgorithmToHash = map[uint8]crypto.Hash{
	RSAMD5:           crypto.MD5,
	DSA:              crypto.SHA1,
	RSASHA1:          crypto.SHA1,
	RSASHA1NSEC3SHA1: crypto.SHA1,
	RSASHA256:        crypto.SHA256,
	ECDSAP256SHA256:  crypto.SHA256,
	ECDSAP384SHA384:  crypto.SHA384,
	RSASHA512:        crypto.SHA512,
	ED25519:          crypto.Hash(0),
}

AlgorithmToHash is a map of algorithm crypto hash IDs to crypto.Hash's.

View Source 
var AlgorithmToString = map[uint8]string{
	RSAMD5:           "RSAMD5",
	DH:               "DH",
	DSA:              "DSA",
	RSASHA1:          "RSASHA1",
	DSANSEC3SHA1:     "DSA-NSEC3-SHA1",
	RSASHA1NSEC3SHA1: "RSASHA1-NSEC3-SHA1",
	RSASHA256:        "RSASHA256",
	RSASHA512:        "RSASHA512",
	ECCGOST:          "ECC-GOST",
	ECDSAP256SHA256:  "ECDSAP256SHA256",
	ECDSAP384SHA384:  "ECDSAP384SHA384",
	ED25519:          "ED25519",
	ED448:            "ED448",
	INDIRECT:         "INDIRECT",
	PRIVATEDNS:       "PRIVATEDNS",
	PRIVATEOID:       "PRIVATEOID",
}

AlgorithmToString is a map of algorithm IDs to algorithm names.

View Source 
var CertTypeToString = map[uint16]string{
	CertPKIX:    "PKIX",
	CertSPKI:    "SPKI",
	CertPGP:     "PGP",
	CertIPIX:    "IPIX",
	CertISPKI:   "ISPKI",
	CertIPGP:    "IPGP",
	CertACPKIX:  "ACPKIX",
	CertIACPKIX: "IACPKIX",
	CertURI:     "URI",
	CertOID:     "OID",
}

CertTypeToString converts the Cert Type to its string representation. See RFC 4398 and RFC 6944.

View Source 
var ClassToString = map[uint16]string{
	ClassINET:   "IN",
	ClassCHAOS:  "CH",
	ClassHESIOD: "HS",
	ClassNONE:   "NONE",
	ClassANY:    "ANY",
}

ClassToString is a maps Classes to strings for each CLASS wire type.

View Source 
var HashToString = map[uint8]string{
	SHA1:   "SHA1",
	SHA256: "SHA256",
	GOST94: "GOST94",
	SHA384: "SHA384",
	SHA512: "SHA512",
}

HashToString is a map of hash IDs to names.

View Source 
var Id = id

Id by default returns a 16-bit random number to be used as a message id. The number is drawn from a cryptographically secure random number generator. This being a variable the function can be reassigned to a custom function. For instance, to make it return a static value for testing: 

dns.Id = func() uint16 { return 3 }
View Source 
var OpcodeToString = map[int]string{
	OpcodeQuery:  "QUERY",
	OpcodeIQuery: "IQUERY",
	OpcodeStatus: "STATUS",
	OpcodeNotify: "NOTIFY",
	OpcodeUpdate: "UPDATE",
}

OpcodeToString maps Opcodes to strings.

View Source 
var RcodeToString = map[int]string{
	RcodeSuccess:        "NOERROR",
	RcodeFormatError:    "FORMERR",
	RcodeServerFailure:  "SERVFAIL",
	RcodeNameError:      "NXDOMAIN",
	RcodeNotImplemented: "NOTIMP",
	RcodeRefused:        "REFUSED",
	RcodeYXDomain:       "YXDOMAIN",
	RcodeYXRrset:        "YXRRSET",
	RcodeNXRrset:        "NXRRSET",
	RcodeNotAuth:        "NOTAUTH",
	RcodeNotZone:        "NOTZONE",
	RcodeBadSig:         "BADSIG",

	RcodeBadKey:    "BADKEY",
	RcodeBadTime:   "BADTIME",
	RcodeBadMode:   "BADMODE",
	RcodeBadName:   "BADNAME",
	RcodeBadAlg:    "BADALG",
	RcodeBadTrunc:  "BADTRUNC",
	RcodeBadCookie: "BADCOOKIE",
}

RcodeToString maps Rcodes to strings.

View Source 
var StringToAlgorithm = reverseInt8(AlgorithmToString)

StringToAlgorithm is the reverse of AlgorithmToString.

View Source 
var StringToCertType = reverseInt16(CertTypeToString)

StringToCertType is the reverseof CertTypeToString.

View Source 
var StringToClass = reverseInt16(ClassToString)

StringToClass is the reverse of ClassToString, needed for string parsing.

View Source 
var StringToHash = reverseInt8(HashToString)

StringToHash is a map of names to hash IDs.

View Source 
var StringToOpcode = reverseInt(OpcodeToString)

StringToOpcode is a map of opcodes to strings.

View Source 
var StringToRcode = reverseInt(RcodeToString)

StringToRcode is a map of rcodes to strings.

View Source 
var StringToType = reverseInt16(TypeToString)

StringToType is the reverse of TypeToString, needed for string parsing.

View Source 
var TypeToRR = map[uint16]func() RR{
	TypeA:       func() RR { return new(A) },
	TypeAAAA:    func() RR { return new(AAAA) },
	TypeAFSDB:   func() RR { return new(AFSDB) },
	TypeANY:     func() RR { return new(ANY) },
	TypeAPL:     func() RR { return new(APL) },
	TypeAVC:     func() RR { return new(AVC) },
	TypeCAA:     func() RR { return new(CAA) },
	TypeCDNSKEY: func() RR { return new(CDNSKEY) },
	TypeCDS:     func() RR { return new(CDS) },
	TypeCERT:    func() RR { return new(CERT) },
	TypeCNAME:   func() RR { return new(CNAME) },
	TypeCSYNC:   func() RR { return new(CSYNC) },
	TypeDHCID:   func() RR { return new(DHCID) },
	TypeDLV:     func() RR { return new(DLV) },
	TypeDNAME:   func() RR { return new(DNAME) },
	TypeDNSKEY:  func() RR { return new(DNSKEY) },
	TypeDS:      func() RR { return new(DS) },

	TypeEUI48: func() RR { return new(EUI48) },
	TypeEUI64: func() RR { return new(EUI64) },

	TypeGPOS:  func() RR { return new(GPOS) },
	TypeHINFO: func() RR { return new(HINFO) },
	TypeHIP:   func() RR { return new(HIP) },
	TypeHTTPS: func() RR { return new(HTTPS) },
	TypeKEY:   func() RR { return new(KEY) },
	TypeKX:    func() RR { return new(KX) },
	TypeL32:   func() RR { return new(L32) },
	TypeL64:   func() RR { return new(L64) },
	TypeLOC:   func() RR { return new(LOC) },
	TypeLP:    func() RR { return new(LP) },

	TypeMF: func() RR { return new(MF) },

	TypeMINFO: func() RR { return new(MINFO) },

	TypeMX:    func() RR { return new(MX) },
	TypeNAPTR: func() RR { return new(NAPTR) },
	TypeNID:   func() RR { return new(NID) },

	TypeNINFO:      func() RR { return new(NINFO) },
	TypeNS:         func() RR { return new(NS) },
	TypeNSAPPTR:    func() RR { return new(NSAPPTR) },
	TypeNSEC:       func() RR { return new(NSEC) },
	TypeNSEC3:      func() RR { return new(NSEC3) },
	TypeNSEC3PARAM: func() RR { return new(NSEC3PARAM) },

	TypeOPENPGPKEY: func() RR { return new(OPENPGPKEY) },
	TypeOPT:        func() RR { return new(OPT) },
	TypePTR:        func() RR { return new(PTR) },
	TypePX:         func() RR { return new(PX) },
	TypeRKEY:       func() RR { return new(RKEY) },
	TypeRP:         func() RR { return new(RP) },
	TypeRRSIG:      func() RR { return new(RRSIG) },
	TypeRT:         func() RR { return new(RT) },
	TypeSIG:        func() RR { return new(SIG) },
	TypeSMIMEA:     func() RR { return new(SMIMEA) },
	TypeSOA:        func() RR { return new(SOA) },
	TypeSPF:        func() RR { return new(SPF) },
	TypeSRV:        func() RR { return new(SRV) },
	TypeSSHFP:      func() RR { return new(SSHFP) },
	TypeSVCB:       func() RR { return new(SVCB) },
	TypeTA:         func() RR { return new(TA) },
	TypeTALINK:     func() RR { return new(TALINK) },
	TypeTKEY:       func() RR { return new(TKEY) },
	TypeTLSA:       func() RR { return new(TLSA) },
	TypeTSIG:       func() RR { return new(TSIG) },
	TypeTXT:        func() RR { return new(TXT) },

	TypeURI: func() RR { return new(URI) },
	TypeX25: func() RR { return new(X25) },
}

TypeToRR is a map of constructors for each RR type.

View Source 
var TypeToString = map[uint16]string{
	TypeA:          "A",
	TypeAAAA:       "AAAA",
	TypeAFSDB:      "AFSDB",
	TypeANY:        "ANY",
	TypeAPL:        "APL",
	TypeATMA:       "ATMA",
	TypeAVC:        "AVC",
	TypeAXFR:       "AXFR",
	TypeCAA:        "CAA",
	TypeCDNSKEY:    "CDNSKEY",
	TypeCDS:        "CDS",
	TypeCERT:       "CERT",
	TypeCNAME:      "CNAME",
	TypeCSYNC:      "CSYNC",
	TypeDHCID:      "DHCID",
	TypeDLV:        "DLV",
	TypeDNAME:      "DNAME",
	TypeDNSKEY:     "DNSKEY",
	TypeDS:         "DS",
	TypeEID:        "EID",
	TypeEUI48:      "EUI48",
	TypeEUI64:      "EUI64",
	TypeGID:        "GID",
	TypeGPOS:       "GPOS",
	TypeHINFO:      "HINFO",
	TypeHIP:        "HIP",
	TypeHTTPS:      "HTTPS",
	TypeIPSECKEY:   "IPSECKEY",
	TypeISDN:       "ISDN",
	TypeIXFR:       "IXFR",
	TypeKEY:        "KEY",
	TypeKX:         "KX",
	TypeL32:        "L32",
	TypeL64:        "L64",
	TypeLOC:        "LOC",
	TypeLP:         "LP",
	TypeMAILA:      "MAILA",
	TypeMAILB:      "MAILB",
	TypeMB:         "MB",
	TypeMD:         "MD",
	TypeMF:         "MF",
	TypeMG:         "MG",
	TypeMINFO:      "MINFO",
	TypeMR:         "MR",
	TypeMX:         "MX",
	TypeNAPTR:      "NAPTR",
	TypeNID:        "NID",
	TypeNIMLOC:     "NIMLOC",
	TypeNINFO:      "NINFO",
	TypeNS:         "NS",
	TypeNSEC:       "NSEC",
	TypeNSEC3:      "NSEC3",
	TypeNSEC3PARAM: "NSEC3PARAM",
	TypeNULL:       "NULL",
	TypeNXT:        "NXT",
	TypeNone:       "None",
	TypeOPENPGPKEY: "OPENPGPKEY",
	TypeOPT:        "OPT",
	TypePTR:        "PTR",
	TypePX:         "PX",
	TypeRKEY:       "RKEY",
	TypeRP:         "RP",
	TypeRRSIG:      "RRSIG",
	TypeRT:         "RT",
	TypeReserved:   "Reserved",
	TypeSIG:        "SIG",
	TypeSINK:       "SINK",
	TypeSMIMEA:     "SMIMEA",
	TypeSOA:        "SOA",
	TypeSPF:        "SPF",
	TypeSRV:        "SRV",
	TypeSSHFP:      "SSHFP",
	TypeSVCB:       "SVCB",
	TypeTA:         "TA",
	TypeTALINK:     "TALINK",
	TypeTKEY:       "TKEY",
	TypeTLSA:       "TLSA",
	TypeTSIG:       "TSIG",
	TypeTXT:        "TXT",
	TypeUID:        "UID",
	TypeUINFO:      "UINFO",
	TypeUNSPEC:     "UNSPEC",
	TypeURI:        "URI",
	TypeX25:        "X25",
	TypeNSAPPTR:    "NSAP-PTR",
}

TypeToString is a map of strings for each RR type.

View Source 
var Version = v{&shadows, 1, 1, 39}

Version is current release version sync with miekg/dns

Functions

func CanonicalName 

func CanonicalName(s string) string

CanonicalName returns the domain name in canonical form. A name in canonical form is lowercase and fully qualified. See Section 6.2 in RFC 4034.

func CertificateToDANE 

func CertificateToDANE(selector, matchingType uint8, cert *x509.Certificate) (string, error)

CertificateToDANE converts a certificate to a hex string as used in the TLSA or SMIMEA records.

func CompareDomainName 

func CompareDomainName(s1, s2 string) (n int)

CompareDomainName compares the names s1 and s2 and returns how many labels they have in common starting from the *right*. The comparison stops at the first inequality. The names are downcased before the comparison.

www.miek.nl. and miek.nl. have two labels in common: miek and nl www.miek.nl. and www.bla.nl. have one label in common: nl

s1 and s2 must be syntactically valid domain names.

func CountLabel 

func CountLabel(s string) (labels int)

CountLabel counts the number of labels in the string s. s must be a syntactically valid domain name.

func Fqdn 

func Fqdn(s string) string

Fqdn return the fully qualified domain name from s. If s is already fully qualified, it behaves as the identity function.

func IsDomainName 

func IsDomainName(s string) (labels int, ok bool)

IsDomainName checks if s is a valid domain name, it returns the number of labels and true, when a domain name is valid. Note that non fully qualified domain name is considered valid, in this case the last label is counted in the number of labels. When false is returned the number of labels is not defined. Also note that this function is extremely liberal; almost any string is a valid domain name as the DNS is 8 bit protocol. It checks if each label fits in 63 characters and that the entire name will fit into the 255 octet wire format limit.

func IsFqdn 

func IsFqdn(s string) bool

IsFqdn checks if a domain name is fully qualified.

func IsMsg 

func IsMsg(buf []byte) error

IsMsg sanity checks buf and returns an error if it isn't a valid DNS packet. The checking is performed on the binary payload.

func IsRRset 

func IsRRset(rrset []RR) bool

IsRRset checks if a set of RRs is a valid RRset as defined by RFC 2181. This means the RRs need to have the same type, name, and class. Returns true if the RR set is valid, otherwise false.

func IsSubDomain 

func IsSubDomain(parent, child string) bool

IsSubDomain checks if child is indeed a child of the parent. If child and parent are the same domain true is returned as well.

func Len 

func Len(r RR) int

Len returns the length (in octets) of the uncompressed RR in wire format.

func NextLabel 

func NextLabel(s string, offset int) (i int, end bool)

NextLabel returns the index of the start of the next label in the string s starting at offset. The bool end is true when the end of the string has been reached. Also see PrevLabel.

func PackDomainName 

func PackDomainName(s string, msg []byte, off int, compression map[string]int, compress bool) (off1 int, err error)

PackDomainName packs a domain name s into msg[off:]. If compression is wanted compress must be true and the compression map needs to hold a mapping between domain names and offsets pointing into msg.

func PackRR 

func PackRR(rr RR, msg []byte, off int, compression map[string]int, compress bool) (off1 int, err error)

PackRR packs a resource record rr into msg[off:]. See PackDomainName for documentation about the compression.

func PrevLabel 

func PrevLabel(s string, n int) (i int, start bool)

PrevLabel returns the index of the label when starting from the right and jumping n labels to the left. The bool start is true when the start of the string has been overshot. Also see NextLabel.

func PrivateHandle 

func PrivateHandle(rtypestr string, rtype uint16, generator func() PrivateRdata)

PrivateHandle registers a private resource record type. It requires string and numeric representation of private RR type and generator function as argument.

func PrivateHandleRemove 

func PrivateHandleRemove(rtype uint16)

PrivateHandleRemove removes definitions required to support private RR type.

func ReverseAddr 

func ReverseAddr(addr string) (arpa string, err error)

ReverseAddr returns the in-addr.arpa. or ip6.arpa. hostname of the IP address suitable for reverse DNS (PTR) record lookups or an error if it fails to parse the IP address.

func SMIMEAName 

func SMIMEAName(email, domain string) (string, error)

SMIMEAName returns the ownername of a SMIMEA resource record as per the format specified in RFC 'draft-ietf-dane-smime-12' Section 2 and 3

func Split 

func Split(s string) []int

Split splits a name s into its label indexes. www.miek.nl. returns []int{0, 4, 9}, www.miek.nl also returns []int{0, 4, 9}. The root name (.) returns nil. Also see SplitDomainName. s must be a syntactically valid domain name.

func SplitDomainName 

func SplitDomainName(s string) (labels []string)

SplitDomainName splits a name string into it's labels. www.miek.nl. returns []string{"www", "miek", "nl"} .www.miek.nl. returns []string{"", "www", "miek", "nl"}, The root label (.) returns nil. Note that using strings.Split(s) will work in most cases, but does not handle escaped dots (\.) for instance. s must be a syntactically valid domain name, see IsDomainName.

func StringToTime 

func StringToTime(s string) (uint32, error)

StringToTime translates the RRSIG's incep. and expir. times from string values like "20110403154150" to an 32 bit integer. It takes serial arithmetic (RFC 1982) into account.

func TLSAName 

func TLSAName(name, service, network string) (string, error)

TLSAName returns the ownername of a TLSA resource record as per the rules specified in RFC 6698, Section 3.

func TimeToString 

func TimeToString(t uint32) string

TimeToString translates the RRSIG's incep. and expir. times to the string representation used when printing the record. It takes serial arithmetic (RFC 1982) into account.

func TsigGenerate 

func TsigGenerate(m *Msg, secret, requestMAC string, timersOnly bool) ([]byte, string, error)

TsigGenerate fills out the TSIG record attached to the message. The message should contain a "stub" TSIG RR with the algorithm, key name (owner name of the RR), time fudge (defaults to 300 seconds) and the current time The TSIG MAC is saved in that Tsig RR. When TsigGenerate is called for the first time requestMAC is set to the empty string and timersOnly is false. If something goes wrong an error is returned, otherwise it is nil.

func TsigVerify 

func TsigVerify(msg []byte, secret, requestMAC string, timersOnly bool) error

TsigVerify verifies the TSIG on a message. If the signature does not validate err contains the error, otherwise it is nil.

func UnpackDomainName 

func UnpackDomainName(msg []byte, off int) (string, int, error)

UnpackDomainName unpacks a domain name into a string. It returns the name, the new offset into msg and any error that occurred.

When an error is encountered, the unpacked name will be discarded and len(msg) will be returned as the offset.

Types

type A 

type A struct {
	Hdr RR_Header
	A   net.IP `dns:"a"`
}

A RR. See RFC 1035.

func (*A) Header 

func (rr *A) Header() *RR_Header

func (*A) String 

func (rr *A) String() string

type AAAA 

type AAAA struct {
	Hdr  RR_Header
	AAAA net.IP `dns:"aaaa"`
}

AAAA RR. See RFC 3596.

func (*AAAA) Header 

func (rr *AAAA) Header() *RR_Header

func (*AAAA) String 

func (rr *AAAA) String() string

type AFSDB 

type AFSDB struct {
	Hdr      RR_Header
	Subtype  uint16
	Hostname string `dns:"domain-name"`
}

AFSDB RR. See RFC 1183.

func (*AFSDB) Header 

func (rr *AFSDB) Header() *RR_Header

func (*AFSDB) String 

func (rr *AFSDB) String() string

type ANY 

type ANY struct {
	Hdr RR_Header
}

ANY is a wild card record. See RFC 1035, Section 3.2.3. ANY is named "*" there.

func (*ANY) Header 

func (rr *ANY) Header() *RR_Header

func (*ANY) String 

func (rr *ANY) String() string

type APL 

type APL struct {
	Hdr      RR_Header
	Prefixes []APLPrefix `dns:"apl"`
}

APL RR. See RFC 3123.

func (*APL) Header 

func (rr *APL) Header() *RR_Header

func (*APL) String 

func (rr *APL) String() string

String returns presentation form of the APL record.

type APLPrefix 

type APLPrefix struct {
	Negation bool
	Network  net.IPNet
}

APLPrefix is an address prefix hold by an APL record.

type AVC 

type AVC struct {
	Hdr RR_Header
	Txt []string `dns:"txt"`
}

AVC RR. See https://www.iana.org/assignments/dns-parameters/AVC/avc-completed-template.

func (*AVC) Header 

func (rr *AVC) Header() *RR_Header

func (*AVC) String 

func (rr *AVC) String() string

type CAA 

type CAA struct {
	Hdr   RR_Header
	Flag  uint8
	Tag   string
	Value string `dns:"octet"`
}

CAA RR. See RFC 6844.

func (*CAA) Header 

func (rr *CAA) Header() *RR_Header

func (*CAA) String 

func (rr *CAA) String() string

rr.Value Is the character-string encoding of the value field as specified in RFC 1035, Section 5.1.

type CDNSKEY 

type CDNSKEY struct {
	DNSKEY
}

CDNSKEY RR. See RFC 7344.

func (*CDNSKEY) Header 

func (rr *CDNSKEY) Header() *RR_Header

type CDS 

type CDS struct{ DS }

CDS RR. See RFC 7344.

func (*CDS) Header 

func (rr *CDS) Header() *RR_Header

type CERT 

type CERT struct {
	Hdr         RR_Header
	Type        uint16
	KeyTag      uint16
	Algorithm   uint8
	Certificate string `dns:"base64"`
}

CERT RR. See RFC 4398.

func (*CERT) Header 

func (rr *CERT) Header() *RR_Header

func (*CERT) String 

func (rr *CERT) String() string

type CNAME 

type CNAME struct {
	Hdr    RR_Header
	Target string `dns:"cdomain-name"`
}

CNAME RR. See RFC 1034.

func (*CNAME) Header 

func (rr *CNAME) Header() *RR_Header

func (*CNAME) String 

func (rr *CNAME) String() string

type CSYNC 

type CSYNC struct {
	Hdr        RR_Header
	Serial     uint32
	Flags      uint16
	TypeBitMap []uint16 `dns:"nsec"`
}

CSYNC RR. See RFC 7477.

func (*CSYNC) Header 

func (rr *CSYNC) Header() *RR_Header

func (*CSYNC) String 

func (rr *CSYNC) String() string

type Class 

type Class uint16

Class is a DNS class.

func (Class) String 

func (c Class) String() string

String returns the string representation for the class c.

type DHCID 

type DHCID struct {
	Hdr    RR_Header
	Digest string `dns:"base64"`
}

DHCID RR. See RFC 4701.

func (*DHCID) Header 

func (rr *DHCID) Header() *RR_Header

func (*DHCID) String 

func (rr *DHCID) String() string

type DLV 

type DLV struct{ DS }

DLV RR. See RFC 4431.

type DNAME 

type DNAME struct {
	Hdr    RR_Header
	Target string `dns:"domain-name"`
}

DNAME RR. See RFC 2672.

func (*DNAME) Header 

func (rr *DNAME) Header() *RR_Header

func (*DNAME) String 

func (rr *DNAME) String() string

type DNSKEY 

type DNSKEY struct {
	Hdr       RR_Header
	Flags     uint16
	Protocol  uint8
	Algorithm uint8
	PublicKey string `dns:"base64"`
}

DNSKEY RR. See RFC 4034 and RFC 3755.

func (*DNSKEY) Generate 

func (k *DNSKEY) Generate(bits int) (crypto.PrivateKey, error)

Generate generates a DNSKEY of the given bit size. The public part is put inside the DNSKEY record. The Algorithm in the key must be set as this will define what kind of DNSKEY will be generated. The ECDSA algorithms imply a fixed keysize, in that case bits should be set to the size of the algorithm.

func (*DNSKEY) Header 

func (rr *DNSKEY) Header() *RR_Header

func (*DNSKEY) KeyTag 

func (k *DNSKEY) KeyTag() uint16

KeyTag calculates the keytag (or key-id) of the DNSKEY.

func (*DNSKEY) NewPrivateKey 

func (k *DNSKEY) NewPrivateKey(s string) (crypto.PrivateKey, error)

NewPrivateKey returns a PrivateKey by parsing the string s. s should be in the same form of the BIND private key files.

func (*DNSKEY) PrivateKeyString 

func (r *DNSKEY) PrivateKeyString(p crypto.PrivateKey) string

PrivateKeyString converts a PrivateKey to a string. This string has the same format as the private-key-file of BIND9 (Private-key-format: v1.3). It needs some info from the key (the algorithm), so its a method of the DNSKEY. It supports *rsa.PrivateKey, *ecdsa.PrivateKey and ed25519.PrivateKey.

func (*DNSKEY) ReadPrivateKey 

func (k *DNSKEY) ReadPrivateKey(q io.Reader, file string) (crypto.PrivateKey, error)

ReadPrivateKey reads a private key from the io.Reader q. The string file is only used in error reporting. The public key must be known, because some cryptographic algorithms embed the public inside the privatekey.

func (*DNSKEY) String 

func (rr *DNSKEY) String() string

func (*DNSKEY) ToCDNSKEY 

func (k *DNSKEY) ToCDNSKEY() *CDNSKEY

ToCDNSKEY converts a DNSKEY record to a CDNSKEY record.

func (*DNSKEY) ToDS 

func (k *DNSKEY) ToDS(h uint8) *DS

ToDS converts a DNSKEY record to a DS record.

type DS 

type DS struct {
	Hdr        RR_Header
	KeyTag     uint16
	Algorithm  uint8
	DigestType uint8
	Digest     string `dns:"hex"`
}

DS RR. See RFC 4034 and RFC 3658.

func (*DS) Header 

func (rr *DS) Header() *RR_Header

func (*DS) String 

func (rr *DS) String() string

func (*DS) ToCDS 

func (d *DS) ToCDS() *CDS

ToCDS converts a DS record to a CDS record.

type EDNS0 

type EDNS0 interface {
	// Option returns the option code for the option.
	Option() uint16

	// String returns the string representation of the option.
	String() string
	// contains filtered or unexported methods
}

EDNS0 defines an EDNS0 Option. An OPT RR can have multiple options appended to it. 

type EDNS0_COOKIE struct {
	Code   uint16 // Always EDNS0COOKIE
	Cookie string // Hex-encoded cookie data
}

The EDNS0_COOKIE option is used to add a DNS Cookie to a message. 

o := new(dns.OPT)
o.Hdr.Name = "."
o.Hdr.Rrtype = dns.TypeOPT
e := new(dns.EDNS0_COOKIE)
e.Code = dns.EDNS0COOKIE
e.Cookie = "24a5ac.."
o.Option = append(o.Option, e)

The Cookie field consists out of a client cookie (RFC 7873 Section 4), that is always 8 bytes. It may then optionally be followed by the server cookie. The server cookie is of variable length, 8 to a maximum of 32 bytes. In other words: 

cCookie := o.Cookie[:16]
sCookie := o.Cookie[16:]

There is no guarantee that the Cookie string has a specific length.

func (*EDNS0_COOKIE) Option 

func (e *EDNS0_COOKIE) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_COOKIE) String 

func (e *EDNS0_COOKIE) String() string

type EDNS0_DAU 

type EDNS0_DAU struct {
	Code    uint16 // Always EDNS0DAU
	AlgCode []uint8
}

EDNS0_DUA implements the EDNS0 "DNSSEC Algorithm Understood" option. See RFC 6975.

func (*EDNS0_DAU) Option 

func (e *EDNS0_DAU) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_DAU) String 

func (e *EDNS0_DAU) String() string

type EDNS0_DHU 

type EDNS0_DHU struct {
	Code    uint16 // Always EDNS0DHU
	AlgCode []uint8
}

EDNS0_DHU implements the EDNS0 "DS Hash Understood" option. See RFC 6975.

func (*EDNS0_DHU) Option 

func (e *EDNS0_DHU) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_DHU) String 

func (e *EDNS0_DHU) String() string

type EDNS0_EXPIRE 

type EDNS0_EXPIRE struct {
	Code   uint16 // Always EDNS0EXPIRE
	Expire uint32
}

EDNS0_EXPIRE implementes the EDNS0 option as described in RFC 7314.

func (*EDNS0_EXPIRE) Option 

func (e *EDNS0_EXPIRE) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_EXPIRE) String 

func (e *EDNS0_EXPIRE) String() string

type EDNS0_LLQ 

type EDNS0_LLQ struct {
	Code      uint16 // Always EDNS0LLQ
	Version   uint16
	Opcode    uint16
	Error     uint16
	Id        uint64
	LeaseLife uint32
}

EDNS0_LLQ stands for Long Lived Queries: http://tools.ietf.org/html/draft-sekar-dns-llq-01 Implemented for completeness, as the EDNS0 type code is assigned.

func (*EDNS0_LLQ) Option 

func (e *EDNS0_LLQ) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_LLQ) String 

func (e *EDNS0_LLQ) String() string

type EDNS0_LOCAL 

type EDNS0_LOCAL struct {
	Code uint16
	Data []byte
}

The EDNS0_LOCAL option is used for local/experimental purposes. The option code is recommended to be within the range [EDNS0LOCALSTART, EDNS0LOCALEND] (RFC6891), although any unassigned code can actually be used. The content of the option is made available in Data, unaltered. Basic use pattern for creating a local option: 

o := new(dns.OPT)
o.Hdr.Name = "."
o.Hdr.Rrtype = dns.TypeOPT
e := new(dns.EDNS0_LOCAL)
e.Code = dns.EDNS0LOCALSTART
e.Data = []byte{72, 82, 74}
o.Option = append(o.Option, e)

func (*EDNS0_LOCAL) Option 

func (e *EDNS0_LOCAL) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_LOCAL) String 

func (e *EDNS0_LOCAL) String() string

type EDNS0_N3U 

type EDNS0_N3U struct {
	Code    uint16 // Always EDNS0N3U
	AlgCode []uint8
}

EDNS0_N3U implements the EDNS0 "NSEC3 Hash Understood" option. See RFC 6975.

func (*EDNS0_N3U) Option 

func (e *EDNS0_N3U) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_N3U) String 

func (e *EDNS0_N3U) String() string

type EDNS0_NSID 

type EDNS0_NSID struct {
	Code uint16 // Always EDNS0NSID
	Nsid string // This string needs to be hex encoded
}

EDNS0_NSID option is used to retrieve a nameserver identifier. When sending a request Nsid must be set to the empty string The identifier is an opaque string encoded as hex. Basic use pattern for creating an nsid option: 

o := new(dns.OPT)
o.Hdr.Name = "."
o.Hdr.Rrtype = dns.TypeOPT
e := new(dns.EDNS0_NSID)
e.Code = dns.EDNS0NSID
e.Nsid = "AA"
o.Option = append(o.Option, e)

func (*EDNS0_NSID) Option 

func (e *EDNS0_NSID) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_NSID) String 

func (e *EDNS0_NSID) String() string

type EDNS0_PADDING 

type EDNS0_PADDING struct {
	Padding []byte
}

EDNS0_PADDING option is used to add padding to a request/response. The default value of padding SHOULD be 0x0 but other values MAY be used, for instance if compression is applied before encryption which may break signatures.

func (*EDNS0_PADDING) Option 

func (e *EDNS0_PADDING) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_PADDING) String 

func (e *EDNS0_PADDING) String() string

type EDNS0_SUBNET 

type EDNS0_SUBNET struct {
	Code          uint16 // Always EDNS0SUBNET
	Family        uint16 // 1 for IP, 2 for IP6
	SourceNetmask uint8
	SourceScope   uint8
	Address       net.IP
}

EDNS0_SUBNET is the subnet option that is used to give the remote nameserver an idea of where the client lives. See RFC 7871. It can then give back a different answer depending on the location or network topology. Basic use pattern for creating an subnet option: 

o := new(dns.OPT)
o.Hdr.Name = "."
o.Hdr.Rrtype = dns.TypeOPT
e := new(dns.EDNS0_SUBNET)
e.Code = dns.EDNS0SUBNET
e.Family = 1	// 1 for IPv4 source address, 2 for IPv6
e.SourceNetmask = 32	// 32 for IPV4, 128 for IPv6
e.SourceScope = 0
e.Address = net.ParseIP("127.0.0.1").To4()	// for IPv4
// e.Address = net.ParseIP("2001:7b8:32a::2")	// for IPV6
o.Option = append(o.Option, e)

This code will parse all the available bits when unpacking (up to optlen). When packing it will apply SourceNetmask. If you need more advanced logic, patches welcome and good luck.

func (*EDNS0_SUBNET) Option 

func (e *EDNS0_SUBNET) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_SUBNET) String 

func (e *EDNS0_SUBNET) String() (s string)

type EDNS0_TCP_KEEPALIVE 

type EDNS0_TCP_KEEPALIVE struct {
	Code    uint16 // Always EDNSTCPKEEPALIVE
	Length  uint16 // the value 0 if the TIMEOUT is omitted, the value 2 if it is present;
	Timeout uint16 // an idle timeout value for the TCP connection, specified in units of 100 milliseconds, encoded in network byte order.
}

EDNS0_TCP_KEEPALIVE is an EDNS0 option that instructs the server to keep the TCP connection alive. See RFC 7828.

func (*EDNS0_TCP_KEEPALIVE) Option 

func (e *EDNS0_TCP_KEEPALIVE) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_TCP_KEEPALIVE) String 

func (e *EDNS0_TCP_KEEPALIVE) String() (s string)

type EDNS0_UL 

type EDNS0_UL struct {
	Code     uint16 // Always EDNS0UL
	Lease    uint32
	KeyLease uint32
}

The EDNS0_UL (Update Lease) (draft RFC) option is used to tell the server to set an expiration on an update RR. This is helpful for clients that cannot clean up after themselves. This is a draft RFC and more information can be found at https://tools.ietf.org/html/draft-sekar-dns-ul-02 

o := new(dns.OPT)
o.Hdr.Name = "."
o.Hdr.Rrtype = dns.TypeOPT
e := new(dns.EDNS0_UL)
e.Code = dns.EDNS0UL
e.Lease = 120 // in seconds
o.Option = append(o.Option, e)

func (*EDNS0_UL) Option 

func (e *EDNS0_UL) Option() uint16

Option implements the EDNS0 interface.

func (*EDNS0_UL) String 

func (e *EDNS0_UL) String() string

type EUI48 

type EUI48 struct {
	Hdr     RR_Header
	Address uint64 `dns:"uint48"`
}

EUI48 RR. See RFC 7043.

func (*EUI48) Header 

func (rr *EUI48) Header() *RR_Header

func (*EUI48) String 

func (rr *EUI48) String() string

type EUI64 

type EUI64 struct {
	Hdr     RR_Header
	Address uint64
}

EUI64 RR. See RFC 7043.

func (*EUI64) Header 

func (rr *EUI64) Header() *RR_Header

func (*EUI64) String 

func (rr *EUI64) String() string

type Error 

type Error struct {
	// contains filtered or unexported fields
}

Error represents a DNS error.

func (*Error) Error 

func (e *Error) Error() string

type GPOS 

type GPOS struct {
	Hdr       RR_Header
	Longitude string
	Latitude  string
	Altitude  string
}

GPOS RR. See RFC 1712.

func (*GPOS) Header 

func (rr *GPOS) Header() *RR_Header

func (*GPOS) String 

func (rr *GPOS) String() string

type HINFO 

type HINFO struct {
	Hdr RR_Header
	Cpu string
	Os  string
}

HINFO RR. See RFC 1034.

func (*HINFO) Header 

func (rr *HINFO) Header() *RR_Header

func (*HINFO) String 

func (rr *HINFO) String() string

type HIP 

type HIP struct {
	Hdr                RR_Header
	HitLength          uint8
	PublicKeyAlgorithm uint8
	PublicKeyLength    uint16
	Hit                string   `dns:"size-hex:HitLength"`
	PublicKey          string   `dns:"size-base64:PublicKeyLength"`
	RendezvousServers  []string `dns:"domain-name"`
}

HIP RR. See RFC 8005.

func (*HIP) Header 

func (rr *HIP) Header() *RR_Header

func (*HIP) String 

func (rr *HIP) String() string

type HTTPS 

type HTTPS struct {
	SVCB
}

HTTPS RR. Everything valid for SVCB applies to HTTPS as well. Except that the HTTPS record is intended for use with the HTTP and HTTPS protocols.

func (*HTTPS) Header 

func (rr *HTTPS) Header() *RR_Header

func (*HTTPS) String 

func (rr *HTTPS) String() string
type Header struct {
	Id                                 uint16
	Bits                               uint16
	Qdcount, Ancount, Nscount, Arcount uint16
}

Header is the wire format for the DNS packet header.

type KEY 

type KEY struct {
	DNSKEY
}

KEY RR. See RFC RFC 2535.

func (*KEY) Header 

func (rr *KEY) Header() *RR_Header

type KX 

type KX struct {
	Hdr        RR_Header
	Preference uint16
	Exchanger  string `dns:"domain-name"`
}

KX RR. See RFC 2230.

func (*KX) Header 

func (rr *KX) Header() *RR_Header

func (*KX) String 

func (rr *KX) String() string

type L32 

type L32 struct {
	Hdr        RR_Header
	Preference uint16
	Locator32  net.IP `dns:"a"`
}

L32 RR, See RFC 6742.

func (*L32) Header 

func (rr *L32) Header() *RR_Header

func (*L32) String 

func (rr *L32) String() string

type L64 

type L64 struct {
	Hdr        RR_Header
	Preference uint16
	Locator64  uint64
}

L64 RR, See RFC 6742.

func (*L64) Header 

func (rr *L64) Header() *RR_Header

func (*L64) String 

func (rr *L64) String() string

type LOC 

type LOC struct {
	Hdr       RR_Header
	Version   uint8
	Size      uint8
	HorizPre  uint8
	VertPre   uint8
	Latitude  uint32
	Longitude uint32
	Altitude  uint32
}

LOC RR. See RFC RFC 1876.

func (*LOC) Header 

func (rr *LOC) Header() *RR_Header

func (*LOC) String 

func (rr *LOC) String() string

type LP 

type LP struct {
	Hdr        RR_Header
	Preference uint16
	Fqdn       string `dns:"domain-name"`
}

LP RR. See RFC 6742.

func (*LP) Header 

func (rr *LP) Header() *RR_Header

func (*LP) String 

func (rr *LP) String() string

type MF 

type MF struct {
	Hdr RR_Header
	Mf  string `dns:"cdomain-name"`
}

MF RR. See RFC 1035.

func (*MF) Header 

func (rr *MF) Header() *RR_Header

func (*MF) String 

func (rr *MF) String() string

type MINFO 

type MINFO struct {
	Hdr   RR_Header
	Rmail string `dns:"cdomain-name"`
	Email string `dns:"cdomain-name"`
}

MINFO RR. See RFC 1035.

func (*MINFO) Header 

func (rr *MINFO) Header() *RR_Header

func (*MINFO) String 

func (rr *MINFO) String() string

type MX 

type MX struct {
	Hdr        RR_Header
	Preference uint16
	Mx         string `dns:"cdomain-name"`
}

MX RR. See RFC 1035.

func (*MX) Header 

func (rr *MX) Header() *RR_Header

func (*MX) String 

func (rr *MX) String() string

type Msg 

type Msg struct {
	MsgHdr
	Compress bool       `json:"-"` // If true, the message will be compressed when converted to wire format.
	Question []Question // Holds the RR(s) of the question section.
	Answer   []RR       // Holds the RR(s) of the answer section.
	Ns       []RR       // Holds the RR(s) of the authority section.
	Extra    []RR       // Holds the RR(s) of the additional section.
}

Msg contains the layout of a DNS message.

func (*Msg) IsEdns0 

func (dns *Msg) IsEdns0() *OPT

IsEdns0 checks if the message has a EDNS0 (OPT) record, any EDNS0 record in the additional section will do. It returns the OPT record found or nil.

func (*Msg) IsTsig 

func (dns *Msg) IsTsig() *TSIG

IsTsig checks if the message has a TSIG record as the last record in the additional section. It returns the TSIG record found or nil.

func (*Msg) Len 

func (dns *Msg) Len() int

Len returns the message length when in (un)compressed wire format. If dns.Compress is true compression it is taken into account. Len() is provided to be a faster way to get the size of the resulting packet, than packing it, measuring the size and discarding the buffer.

func (*Msg) Pack 

func (dns *Msg) Pack() (msg []byte, err error)

Pack packs a Msg: it is converted to to wire format. If the dns.Compress is true the message will be in compressed wire format.

func (*Msg) PackBuffer 

func (dns *Msg) PackBuffer(buf []byte) (msg []byte, err error)

PackBuffer packs a Msg, using the given buffer buf. If buf is too small a new buffer is allocated.

func (*Msg) SetAxfr 

func (dns *Msg) SetAxfr(z string) *Msg

SetAxfr creates message for requesting an AXFR.

func (*Msg) SetEdns0 

func (dns *Msg) SetEdns0(udpsize uint16, do bool) *Msg

SetEdns0 appends a EDNS0 OPT RR to the message. TSIG should always the last RR in a message.

func (*Msg) SetIxfr 

func (dns *Msg) SetIxfr(z string, serial uint32, ns, mbox string) *Msg

SetIxfr creates message for requesting an IXFR.

func (*Msg) SetNotify 

func (dns *Msg) SetNotify(z string) *Msg

SetNotify creates a notify message, it sets the Question section, generates an Id and sets the Authoritative (AA) bit to true.

func (*Msg) SetQuestion 

func (dns *Msg) SetQuestion(z string, t uint16) *Msg

SetQuestion creates a question message, it sets the Question section, generates an Id and sets the RecursionDesired (RD) bit to true.

func (*Msg) SetRcode 

func (dns *Msg) SetRcode(request *Msg, rcode int) *Msg

SetRcode creates an error message suitable for the request.

func (*Msg) SetRcodeFormatError 

func (dns *Msg) SetRcodeFormatError(request *Msg) *Msg

SetRcodeFormatError creates a message with FormError set.

func (*Msg) SetReply 

func (dns *Msg) SetReply(request *Msg) *Msg

SetReply creates a reply message from a request message.

func (*Msg) SetTsig 

func (dns *Msg) SetTsig(z, algo string, fudge uint16, timesigned int64) *Msg

SetTsig appends a TSIG RR to the message. This is only a skeleton TSIG RR that is added as the last RR in the additional section. The TSIG is calculated when the message is being send.

func (*Msg) SetUpdate 

func (dns *Msg) SetUpdate(z string) *Msg

SetUpdate makes the message a dynamic update message. It sets the ZONE section to: z, TypeSOA, ClassINET.

func (*Msg) String 

func (dns *Msg) String() string

Convert a complete message to a string with dig-like output.

func (*Msg) Truncate 

func (dns *Msg) Truncate(size int)

Truncate ensures the reply message will fit into the requested buffer size by removing records that exceed the requested size.

It will first check if the reply fits without compression and then with compression. If it won't fit with compression, Truncate then walks the record adding as many records as possible without exceeding the requested buffer size.

The TC bit will be set if any records were excluded from the message. If the TC bit is already set on the message it will be retained. TC indicates that the client should retry over TCP.

According to RFC 2181, the TC bit should only be set if not all of the "required" RRs can be included in the response. Unfortunately, we have no way of knowing which RRs are required so we set the TC bit if any RR had to be omitted from the response.

The appropriate buffer size can be retrieved from the requests OPT record, if present, and is transport specific otherwise. dns.MinMsgSize should be used for UDP requests without an OPT record, and dns.MaxMsgSize for TCP requests without an OPT record.

func (*Msg) Unpack 

func (dns *Msg) Unpack(msg []byte) (err error)

Unpack unpacks a binary message to a Msg structure.

func (*Msg) UnpackWithTypes 

func (dns *Msg) UnpackWithTypes(dh *Header, msg []byte, off int, known_types map[uint16]func() RR) (err error)

func (*Msg) Unpack_TS 

func (dns *Msg) Unpack_TS(msg []byte, known_types map[uint16]func() RR) (err error)

type MsgHdr 

type MsgHdr struct {
	Id                 uint16
	Response           bool
	Opcode             int
	Authoritative      bool
	Truncated          bool
	RecursionDesired   bool
	RecursionAvailable bool
	Zero               bool
	AuthenticatedData  bool
	CheckingDisabled   bool
	Rcode              int
}

MsgHdr is a a manually-unpacked version of (id, bits).

func (*MsgHdr) String 

func (h *MsgHdr) String() string

Convert a MsgHdr to a string, with dig-like headers:

;; opcode: QUERY, status: NOERROR, id: 48404

;; flags: qr aa rd ra;

type NAPTR 

type NAPTR struct {
	Hdr         RR_Header
	Order       uint16
	Preference  uint16
	Flags       string
	Service     string
	Regexp      string
	Replacement string `dns:"domain-name"`
}

NAPTR RR. See RFC 2915.

func (*NAPTR) Header 

func (rr *NAPTR) Header() *RR_Header

func (*NAPTR) String 

func (rr *NAPTR) String() string

type NID 

type NID struct {
	Hdr        RR_Header
	Preference uint16
	NodeID     uint64
}

NID RR. See RFC RFC 6742.

func (*NID) Header 

func (rr *NID) Header() *RR_Header

func (*NID) String 

func (rr *NID) String() string

type NINFO 

type NINFO struct {
	Hdr    RR_Header
	ZSData []string `dns:"txt"`
}

NINFO RR. See https://www.iana.org/assignments/dns-parameters/NINFO/ninfo-completed-template.

func (*NINFO) Header 

func (rr *NINFO) Header() *RR_Header

func (*NINFO) String 

func (rr *NINFO) String() string

type NS 

type NS struct {
	Hdr RR_Header
	Ns  string `dns:"cdomain-name"`
}

NS RR. See RFC 1035.

func (*NS) Header 

func (rr *NS) Header() *RR_Header

func (*NS) String 

func (rr *NS) String() string

type NSAPPTR 

type NSAPPTR struct {
	Hdr RR_Header
	Ptr string `dns:"domain-name"`
}

NSAPPTR RR. See RFC 1348.

func (*NSAPPTR) Header 

func (rr *NSAPPTR) Header() *RR_Header

func (*NSAPPTR) String 

func (rr *NSAPPTR) String() string

type NSEC 

type NSEC struct {
	Hdr        RR_Header
	NextDomain string   `dns:"domain-name"`
	TypeBitMap []uint16 `dns:"nsec"`
}

NSEC RR. See RFC 4034 and RFC 3755.

func (*NSEC) Header 

func (rr *NSEC) Header() *RR_Header

func (*NSEC) String 

func (rr *NSEC) String() string

type NSEC3 

type NSEC3 struct {
	Hdr        RR_Header
	Hash       uint8
	Flags      uint8
	Iterations uint16
	SaltLength uint8
	Salt       string `dns:"size-hex:SaltLength"`
	HashLength uint8
	NextDomain string   `dns:"size-base32:HashLength"`
	TypeBitMap []uint16 `dns:"nsec"`
}

NSEC3 RR. See RFC 5155.

func (*NSEC3) Header 

func (rr *NSEC3) Header() *RR_Header

func (*NSEC3) String 

func (rr *NSEC3) String() string

type NSEC3PARAM 

type NSEC3PARAM struct {
	Hdr        RR_Header
	Hash       uint8
	Flags      uint8
	Iterations uint16
	SaltLength uint8
	Salt       string `dns:"size-hex:SaltLength"`
}

NSEC3PARAM RR. See RFC 5155.

func (*NSEC3PARAM) Header 

func (rr *NSEC3PARAM) Header() *RR_Header

func (*NSEC3PARAM) String 

func (rr *NSEC3PARAM) String() string

type Name 

type Name string

Name is a DNS domain name.

func (Name) String 

func (n Name) String() string

String returns the string representation for the name n.

type OPENPGPKEY 

type OPENPGPKEY struct {
	Hdr       RR_Header
	PublicKey string `dns:"base64"`
}

OPENPGPKEY RR. See RFC 7929.

func (*OPENPGPKEY) Header 

func (rr *OPENPGPKEY) Header() *RR_Header

func (*OPENPGPKEY) String 

func (rr *OPENPGPKEY) String() string

type OPT 

type OPT struct {
	Hdr    RR_Header
	Option []EDNS0 `dns:"opt"`
}

OPT is the EDNS0 RR appended to messages to convey extra (meta) information. See RFC 6891.

func (*OPT) Do 

func (rr *OPT) Do() bool

Do returns the value of the DO (DNSSEC OK) bit.

func (*OPT) ExtendedRcode 

func (rr *OPT) ExtendedRcode() int

ExtendedRcode returns the EDNS extended RCODE field (the upper 8 bits of the TTL).

func (*OPT) Header 

func (rr *OPT) Header() *RR_Header

func (*OPT) SetDo 

func (rr *OPT) SetDo(do ...bool)

SetDo sets the DO (DNSSEC OK) bit. If we pass an argument, set the DO bit to that value. It is possible to pass 2 or more arguments. Any arguments after the 1st is silently ignored.

func (*OPT) SetExtendedRcode 

func (rr *OPT) SetExtendedRcode(v uint16)

SetExtendedRcode sets the EDNS extended RCODE field.

If the RCODE is not an extended RCODE, will reset the extended RCODE field to 0.

func (*OPT) SetUDPSize 

func (rr *OPT) SetUDPSize(size uint16)

SetUDPSize sets the UDP buffer size.

func (*OPT) SetVersion 

func (rr *OPT) SetVersion(v uint8)

SetVersion sets the version of EDNS. This is usually zero.

func (*OPT) String 

func (rr *OPT) String() string

func (*OPT) UDPSize 

func (rr *OPT) UDPSize() uint16

UDPSize returns the UDP buffer size.

func (*OPT) Version 

func (rr *OPT) Version() uint8

Version returns the EDNS version used. Only zero is defined.

type PTR 

type PTR struct {
	Hdr RR_Header
	Ptr string `dns:"cdomain-name"`
}

PTR RR. See RFC 1035.

func (*PTR) Header 

func (rr *PTR) Header() *RR_Header

func (*PTR) String 

func (rr *PTR) String() string

type PX 

type PX struct {
	Hdr        RR_Header
	Preference uint16
	Map822     string `dns:"domain-name"`
	Mapx400    string `dns:"domain-name"`
}

PX RR. See RFC 2163.

func (*PX) Header 

func (rr *PX) Header() *RR_Header

func (*PX) String 

func (rr *PX) String() string

type ParseError 

type ParseError struct {
	// contains filtered or unexported fields
}

ParseError is a parsing error. It contains the parse error and the location in the io.Reader where the error occurred.

func (*ParseError) Error 

func (e *ParseError) Error() (s string)

type PrivateRR 

type PrivateRR struct {
	Hdr  RR_Header
	Data PrivateRdata
	// contains filtered or unexported fields
}

PrivateRR represents an RR that uses a PrivateRdata user-defined type. It mocks normal RRs and implements dns.RR interface.

func (*PrivateRR) Header 

func (r *PrivateRR) Header() *RR_Header

Header return the RR header of r.

func (*PrivateRR) String 

func (r *PrivateRR) String() string

type PrivateRdata 

type PrivateRdata interface {
	// String returns the text presentaton of the Rdata of the Private RR.
	String() string
	// Pack is used when packing a private RR into a buffer.
	Pack([]byte) (int, error)
	// Unpack is used when unpacking a private RR from a buffer.
	Unpack([]byte) (int, error)
	// Len returns the length in octets of the Rdata.
	Len() int
}

PrivateRdata is an interface used for implementing "Private Use" RR types, see RFC 6895. This allows one to experiment with new RR types, without requesting an official type code. Also see dns.PrivateHandle and dns.PrivateHandleRemove.

type Question 

type Question struct {
	Name   string `dns:"cdomain-name"` // "cdomain-name" specifies encoding (and may be compressed)
	Qtype  uint16
	Qclass uint16
}

Question holds a DNS question. Usually there is just one. While the original DNS RFCs allow multiple questions in the question section of a message, in practice it never works. Because most DNS servers see multiple questions as an error, it is recommended to only have one question per message.

func (*Question) String 

func (q *Question) String() (s string)

type RFC3597 

type RFC3597 struct {
	Hdr   RR_Header
	Rdata string `dns:"hex"`
}

RFC3597 represents an unknown/generic RR. See RFC 3597.

func (*RFC3597) Header 

func (rr *RFC3597) Header() *RR_Header

func (*RFC3597) String 

func (rr *RFC3597) String() string

func (*RFC3597) ToRFC3597 

func (rr *RFC3597) ToRFC3597(r RR) error

ToRFC3597 converts a known RR to the unknown RR representation from RFC 3597.

type RKEY 

type RKEY struct {
	Hdr       RR_Header
	Flags     uint16
	Protocol  uint8
	Algorithm uint8
	PublicKey string `dns:"base64"`
}

RKEY RR. See https://www.iana.org/assignments/dns-parameters/RKEY/rkey-completed-template.

func (*RKEY) Header 

func (rr *RKEY) Header() *RR_Header

func (*RKEY) String 

func (rr *RKEY) String() string

type RP 

type RP struct {
	Hdr  RR_Header
	Mbox string `dns:"domain-name"`
	Txt  string `dns:"domain-name"`
}

RP RR. See RFC 1138, Section 2.2.

func (*RP) Header 

func (rr *RP) Header() *RR_Header

func (*RP) String 

func (rr *RP) String() string

type RR 

type RR interface {
	// Header returns the header of an resource record. The header contains
	// everything up to the rdata.
	Header() *RR_Header
	// String returns the text representation of the resource record.
	String() string
	// contains filtered or unexported methods
}

An RR represents a resource record.

func UnpackRR 

func UnpackRR(msg []byte, off int) (rr RR, off1 int, err error)

UnpackRR unpacks msg[off:] into an RR.

func UnpackRRWithHeader 

func UnpackRRWithHeader(h RR_Header, msg []byte, off int) (rr RR, off1 int, err error)

type RRSIG 

type RRSIG struct {
	Hdr         RR_Header
	TypeCovered uint16
	Algorithm   uint8
	Labels      uint8
	OrigTtl     uint32
	Expiration  uint32
	Inception   uint32
	KeyTag      uint16
	SignerName  string `dns:"domain-name"`
	Signature   string `dns:"base64"`
}

RRSIG RR. See RFC 4034 and RFC 3755.

func (*RRSIG) Header 

func (rr *RRSIG) Header() *RR_Header

func (*RRSIG) Sign 

func (rr *RRSIG) Sign(k crypto.Signer, rrset []RR) error

Sign signs an RRSet. The signature needs to be filled in with the values: Inception, Expiration, KeyTag, SignerName and Algorithm. The rest is copied from the RRset. Sign returns a non-nill error when the signing went OK. There is no check if RRSet is a proper (RFC 2181) RRSet. If OrigTTL is non zero, it is used as-is, otherwise the TTL of the RRset is used as the OrigTTL.

func (*RRSIG) String 

func (rr *RRSIG) String() string

func (*RRSIG) ValidityPeriod 

func (rr *RRSIG) ValidityPeriod(t time.Time) bool

ValidityPeriod uses RFC1982 serial arithmetic to calculate if a signature period is valid. If t is the zero time, the current time is taken other t is. Returns true if the signature is valid at the given time, otherwise returns false.

func (*RRSIG) Verify 

func (rr *RRSIG) Verify(k *DNSKEY, rrset []RR) error

Verify validates an RRSet with the signature and key. This is only the cryptographic test, the signature validity period must be checked separately. This function copies the rdata of some RRs (to lowercase domain names) for the validation to work.

type RR_Header 

type RR_Header struct {
	Name     string `dns:"cdomain-name"`
	Rrtype   uint16
	Class    uint16
	Ttl      uint32
	Rdlength uint16 // Length of data after header.
}

RR_Header is the header all DNS resource records share.

func (*RR_Header) Header 

func (h *RR_Header) Header() *RR_Header

Header returns itself. This is here to make RR_Header implements the RR interface.

func (*RR_Header) String 

func (h *RR_Header) String() string

type RT 

type RT struct {
	Hdr        RR_Header
	Preference uint16
	Host       string `dns:"domain-name"` // RFC 3597 prohibits compressing records not defined in RFC 1035.
}

RT RR. See RFC 1183, Section 3.3.

func (*RT) Header 

func (rr *RT) Header() *RR_Header

func (*RT) String 

func (rr *RT) String() string

type SIG 

type SIG struct {
	RRSIG
}

SIG RR. See RFC 2535. The SIG RR is identical to RRSIG and nowadays only used for SIG(0), See RFC 2931.

func (*SIG) Header 

func (rr *SIG) Header() *RR_Header

func (*SIG) Sign 

func (rr *SIG) Sign(k crypto.Signer, m *Msg) ([]byte, error)

Sign signs a dns.Msg. It fills the signature with the appropriate data. The SIG record should have the SignerName, KeyTag, Algorithm, Inception and Expiration set.

func (*SIG) Verify 

func (rr *SIG) Verify(k *KEY, buf []byte) error

Verify validates the message buf using the key k. It's assumed that buf is a valid message from which rr was unpacked.

type SMIMEA 

type SMIMEA struct {
	Hdr          RR_Header
	Usage        uint8
	Selector     uint8
	MatchingType uint8
	Certificate  string `dns:"hex"`
}

SMIMEA RR. See RFC 8162.

func (*SMIMEA) Header 

func (rr *SMIMEA) Header() *RR_Header

func (*SMIMEA) Sign 

func (r *SMIMEA) Sign(usage, selector, matchingType int, cert *x509.Certificate) (err error)

Sign creates a SMIMEA record from an SSL certificate.

func (*SMIMEA) String 

func (rr *SMIMEA) String() string

func (*SMIMEA) Verify 

func (r *SMIMEA) Verify(cert *x509.Certificate) error

Verify verifies a SMIMEA record against an SSL certificate. If it is OK a nil error is returned.

type SOA 

type SOA struct {
	Hdr     RR_Header
	Ns      string `dns:"cdomain-name"`
	Mbox    string `dns:"cdomain-name"`
	Serial  uint32
	Refresh uint32
	Retry   uint32
	Expire  uint32
	Minttl  uint32
}

SOA RR. See RFC 1035.

func (*SOA) Header 

func (rr *SOA) Header() *RR_Header

func (*SOA) String 

func (rr *SOA) String() string

type SPF 

type SPF struct {
	Hdr RR_Header
	Txt []string `dns:"txt"`
}

SPF RR. See RFC 4408, Section 3.1.1.

func (*SPF) Header 

func (rr *SPF) Header() *RR_Header

func (*SPF) String 

func (rr *SPF) String() string

type SRV 

type SRV struct {
	Hdr      RR_Header
	Priority uint16
	Weight   uint16
	Port     uint16
	Target   string `dns:"domain-name"`
}

SRV RR. See RFC 2782.

func (*SRV) Header 

func (rr *SRV) Header() *RR_Header

func (*SRV) String 

func (rr *SRV) String() string

type SSHFP 

type SSHFP struct {
	Hdr         RR_Header
	Algorithm   uint8
	Type        uint8
	FingerPrint string `dns:"hex"`
}

SSHFP RR. See RFC RFC 4255.

func (*SSHFP) Header 

func (rr *SSHFP) Header() *RR_Header

func (*SSHFP) String 

func (rr *SSHFP) String() string

type SVCB 

type SVCB struct {
	Hdr      RR_Header
	Priority uint16
	Target   string         `dns:"domain-name"`
	Value    []SVCBKeyValue `dns:"pairs"` // Value must be empty if Priority is zero.
}

SVCB RR. See RFC xxxx (https://tools.ietf.org/html/draft-ietf-dnsop-svcb-https-01).

func (*SVCB) Header 

func (rr *SVCB) Header() *RR_Header

func (*SVCB) String 

func (rr *SVCB) String() string

type SVCBAlpn 

type SVCBAlpn struct {
	Alpn []string
}

SVCBAlpn pair is used to list supported connection protocols. Protocol ids can be found at: https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#alpn-protocol-ids Basic use pattern for creating an alpn option: 

h := new(dns.HTTPS)
h.Hdr = dns.RR_Header{Name: ".", Rrtype: dns.TypeHTTPS, Class: dns.ClassINET}
e := new(dns.SVCBAlpn)
e.Alpn = []string{"h2", "http/1.1"}
h.Value = append(o.Value, e)

func (*SVCBAlpn) Key 

func (*SVCBAlpn) Key() SVCBKey

func (*SVCBAlpn) String 

func (s *SVCBAlpn) String() string

type SVCBECHConfig 

type SVCBECHConfig struct {
	ECH []byte
}

SVCBECHConfig pair contains the ECHConfig structure defined in draft-ietf-tls-esni [RFC xxxx]. Basic use pattern for creating an echconfig option: 

h := new(dns.HTTPS)
h.Hdr = dns.RR_Header{Name: ".", Rrtype: dns.TypeHTTPS, Class: dns.ClassINET}
e := new(dns.SVCBECHConfig)
e.ECH = []byte{0xfe, 0x08, ...}
h.Value = append(h.Value, e)

func (*SVCBECHConfig) Key 

func (*SVCBECHConfig) Key() SVCBKey

func (*SVCBECHConfig) String 

func (s *SVCBECHConfig) String() string

type SVCBIPv4Hint 

type SVCBIPv4Hint struct {
	Hint []net.IP
}

SVCBIPv4Hint pair suggests an IPv4 address which may be used to open connections if A and AAAA record responses for SVCB's Target domain haven't been received. In that case, optionally, A and AAAA requests can be made, after which the connection to the hinted IP address may be terminated and a new connection may be opened. Basic use pattern for creating an ipv4hint option: 

	h := new(dns.HTTPS)
	h.Hdr = dns.RR_Header{Name: ".", Rrtype: dns.TypeHTTPS, Class: dns.ClassINET}
	e := new(dns.SVCBIPv4Hint)
	e.Hint = []net.IP{net.IPv4(1,1,1,1).To4()}

 Or

	e.Hint = []net.IP{net.ParseIP("1.1.1.1").To4()}
	h.Value = append(h.Value, e)

func (*SVCBIPv4Hint) Key 

func (*SVCBIPv4Hint) Key() SVCBKey

func (*SVCBIPv4Hint) String 

func (s *SVCBIPv4Hint) String() string

type SVCBIPv6Hint 

type SVCBIPv6Hint struct {
	Hint []net.IP
}

SVCBIPv6Hint pair suggests an IPv6 address which may be used to open connections if A and AAAA record responses for SVCB's Target domain haven't been received. In that case, optionally, A and AAAA requests can be made, after which the connection to the hinted IP address may be terminated and a new connection may be opened. Basic use pattern for creating an ipv6hint option: 

h := new(dns.HTTPS)
h.Hdr = dns.RR_Header{Name: ".", Rrtype: dns.TypeHTTPS, Class: dns.ClassINET}
e := new(dns.SVCBIPv6Hint)
e.Hint = []net.IP{net.ParseIP("2001:db8::1")}
h.Value = append(h.Value, e)

func (*SVCBIPv6Hint) Key 

func (*SVCBIPv6Hint) Key() SVCBKey

func (*SVCBIPv6Hint) String 

func (s *SVCBIPv6Hint) String() string

type SVCBKey 

type SVCBKey uint16
const (
	SVCB_MANDATORY       SVCBKey = 0
	SVCB_ALPN            SVCBKey = 1
	SVCB_NO_DEFAULT_ALPN SVCBKey = 2
	SVCB_PORT            SVCBKey = 3
	SVCB_IPV4HINT        SVCBKey = 4
	SVCB_ECHCONFIG       SVCBKey = 5
	SVCB_IPV6HINT        SVCBKey = 6
)

Keys defined in draft-ietf-dnsop-svcb-https-01 Section 12.3.2.

func (SVCBKey) String 

func (key SVCBKey) String() string

String takes the numerical code of an SVCB key and returns its name. Returns an empty string for reserved keys. Accepts unassigned keys as well as experimental/private keys.

type SVCBKeyValue 

type SVCBKeyValue interface {
	Key() SVCBKey // Key returns the numerical key code.

	String() string // String returns the string representation of the value.
	// contains filtered or unexported methods
}

SVCBKeyValue defines a key=value pair for the SVCB RR type. An SVCB RR can have multiple SVCBKeyValues appended to it.

type SVCBLocal 

type SVCBLocal struct {
	KeyCode SVCBKey // Never 65535 or any assigned keys.
	Data    []byte  // All byte sequences are allowed.
}

SVCBLocal pair is intended for experimental/private use. The key is recommended to be in the range [SVCB_PRIVATE_LOWER, SVCB_PRIVATE_UPPER]. Basic use pattern for creating a keyNNNNN option: 

h := new(dns.HTTPS)
h.Hdr = dns.RR_Header{Name: ".", Rrtype: dns.TypeHTTPS, Class: dns.ClassINET}
e := new(dns.SVCBLocal)
e.KeyCode = 65400
e.Data = []byte("abc")
h.Value = append(h.Value, e)

func (*SVCBLocal) Key 

func (s *SVCBLocal) Key() SVCBKey

func (*SVCBLocal) String 

func (s *SVCBLocal) String() string

type SVCBMandatory 

type SVCBMandatory struct {
	Code []SVCBKey // Must not include mandatory
}

SVCBMandatory pair adds to required keys that must be interpreted for the RR to be functional. Basic use pattern for creating a mandatory option: 

s := &dns.SVCB{Hdr: dns.RR_Header{Name: ".", Rrtype: dns.TypeSVCB, Class: dns.ClassINET}}
e := new(dns.SVCBMandatory)
e.Code = []uint16{65403}
s.Value = append(s.Value, e)

func (*SVCBMandatory) Key 

func (*SVCBMandatory) Key() SVCBKey

func (*SVCBMandatory) String 

func (s *SVCBMandatory) String() string

type SVCBNoDefaultAlpn 

type SVCBNoDefaultAlpn struct{}

SVCBNoDefaultAlpn pair signifies no support for default connection protocols. Basic use pattern for creating a no-default-alpn option: 

s := &dns.SVCB{Hdr: dns.RR_Header{Name: ".", Rrtype: dns.TypeSVCB, Class: dns.ClassINET}}
e := new(dns.SVCBNoDefaultAlpn)
s.Value = append(s.Value, e)

func (*SVCBNoDefaultAlpn) Key 

func (*SVCBNoDefaultAlpn) Key() SVCBKey

func (*SVCBNoDefaultAlpn) String 

func (*SVCBNoDefaultAlpn) String() string

type SVCBPort 

type SVCBPort struct {
	Port uint16
}

SVCBPort pair defines the port for connection. Basic use pattern for creating a port option: 

s := &dns.SVCB{Hdr: dns.RR_Header{Name: ".", Rrtype: dns.TypeSVCB, Class: dns.ClassINET}}
e := new(dns.SVCBPort)
e.Port = 80
s.Value = append(s.Value, e)

func (*SVCBPort) Key 

func (*SVCBPort) Key() SVCBKey

func (*SVCBPort) String 

func (s *SVCBPort) String() string

type TA 

type TA struct {
	Hdr        RR_Header
	KeyTag     uint16
	Algorithm  uint8
	DigestType uint8
	Digest     string `dns:"hex"`
}

TA RR. See http://www.watson.org/~weiler/INI1999-19.pdf.

func (*TA) Header 

func (rr *TA) Header() *RR_Header

func (*TA) String 

func (rr *TA) String() string
type TALINK struct {
	Hdr          RR_Header
	PreviousName string `dns:"domain-name"`
	NextName     string `dns:"domain-name"`
}

TALINK RR. See https://www.iana.org/assignments/dns-parameters/TALINK/talink-completed-template.

func (*TALINK) Header 

func (rr *TALINK) Header() *RR_Header

func (*TALINK) String 

func (rr *TALINK) String() string

type TKEY 

type TKEY struct {
	Hdr        RR_Header
	Algorithm  string `dns:"domain-name"`
	Inception  uint32
	Expiration uint32
	Mode       uint16
	Error      uint16
	KeySize    uint16
	Key        string `dns:"size-hex:KeySize"`
	OtherLen   uint16
	OtherData  string `dns:"size-hex:OtherLen"`
}

TKEY RR. See RFC 2930.

func (*TKEY) Header 

func (rr *TKEY) Header() *RR_Header

func (*TKEY) String 

func (rr *TKEY) String() string

TKEY has no official presentation format, but this will suffice.

type TLSA 

type TLSA struct {
	Hdr          RR_Header
	Usage        uint8
	Selector     uint8
	MatchingType uint8
	Certificate  string `dns:"hex"`
}

TLSA RR. See RFC 6698.

func (*TLSA) Header 

func (rr *TLSA) Header() *RR_Header

func (*TLSA) Sign 

func (r *TLSA) Sign(usage, selector, matchingType int, cert *x509.Certificate) (err error)

Sign creates a TLSA record from an SSL certificate.

func (*TLSA) String 

func (rr *TLSA) String() string

func (*TLSA) Verify 

func (r *TLSA) Verify(cert *x509.Certificate) error

Verify verifies a TLSA record against an SSL certificate. If it is OK a nil error is returned.

type TSIG 

type TSIG struct {
	Hdr        RR_Header
	Algorithm  string `dns:"domain-name"`
	TimeSigned uint64 `dns:"uint48"`
	Fudge      uint16
	MACSize    uint16
	MAC        string `dns:"size-hex:MACSize"`
	OrigId     uint16
	Error      uint16
	OtherLen   uint16
	OtherData  string `dns:"size-hex:OtherLen"`
}

TSIG is the RR the holds the transaction signature of a message. See RFC 2845 and RFC 4635.

func (*TSIG) Header 

func (rr *TSIG) Header() *RR_Header

func (*TSIG) String 

func (rr *TSIG) String() string

type TXT 

type TXT struct {
	Hdr RR_Header
	Txt []string `dns:"txt"`
}

TXT RR. See RFC 1035.

func (*TXT) Header 

func (rr *TXT) Header() *RR_Header

func (*TXT) String 

func (rr *TXT) String() string

type TsigProvider 

type TsigProvider interface {
	// Generate is passed the DNS message to be signed and the partial TSIG RR. It returns the signature and nil, otherwise an error.
	Generate(msg []byte, t *TSIG) ([]byte, error)
	// Verify is passed the DNS message to be verified and the TSIG RR. If the signature is valid it will return nil, otherwise an error.
	Verify(msg []byte, t *TSIG) error
}

TsigProvider provides the API to plug-in a custom TSIG implementation.

type Type 

type Type uint16

Type is a DNS type.

func (Type) String 

func (t Type) String() string

String returns the string representation for the type t.

type URI 

type URI struct {
	Hdr      RR_Header
	Priority uint16
	Weight   uint16
	Target   string `dns:"octet"`
}

URI RR. See RFC 7553.

func (*URI) Header 

func (rr *URI) Header() *RR_Header

func (*URI) String 

func (rr *URI) String() string

rr.Target to be parsed as a sequence of character encoded octets according to RFC 3986

type UnknownRR 

type UnknownRR struct {
	Hdr   RR_Header
	Rdata []byte
}

UnknownRR delegates RFC3597 call ToRFC3597 if drilling

func (*UnknownRR) Header 

func (rr *UnknownRR) Header() *RR_Header

func (*UnknownRR) String 

func (rr *UnknownRR) String() string

type X25 

type X25 struct {
	Hdr         RR_Header
	PSDNAddress string
}

X25 RR. See RFC 1183, Section 3.1.

func (*X25) Header 

func (rr *X25) Header() *RR_Header

func (*X25) String 

func (rr *X25) String() string

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