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package dns
import (
"encoding/binary"
"encoding/hex"
"errors"
"fmt"
"net"
"strconv"
)
// EDNS0 Option codes.
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)
_DO = 1 << 15 // DNSSEC OK
)
// OPT is the EDNS0 RR appended to messages to convey extra (meta) information.
// See RFC 6891.
type OPT struct {
Hdr RR_Header
Option []EDNS0 `dns:"opt"`
}
func (rr *OPT) String() string {
s := "\n;; OPT PSEUDOSECTION:\n; EDNS: version " + strconv.Itoa(int(rr.Version())) + "; "
if rr.Do() {
s += "flags: do; "
} else {
s += "flags: ; "
}
s += "udp: " + strconv.Itoa(int(rr.UDPSize()))
for _, o := range rr.Option {
switch o.(type) {
case *EDNS0_NSID:
s += "\n; NSID: " + o.String()
h, e := o.pack()
var r string
if e == nil {
for _, c := range h {
r += "(" + string(c) + ")"
}
s += " " + r
}
case *EDNS0_SUBNET:
s += "\n; SUBNET: " + o.String()
case *EDNS0_COOKIE:
s += "\n; COOKIE: " + o.String()
case *EDNS0_UL:
s += "\n; UPDATE LEASE: " + o.String()
case *EDNS0_LLQ:
s += "\n; LONG LIVED QUERIES: " + o.String()
case *EDNS0_DAU:
s += "\n; DNSSEC ALGORITHM UNDERSTOOD: " + o.String()
case *EDNS0_DHU:
s += "\n; DS HASH UNDERSTOOD: " + o.String()
case *EDNS0_N3U:
s += "\n; NSEC3 HASH UNDERSTOOD: " + o.String()
case *EDNS0_LOCAL:
s += "\n; LOCAL OPT: " + o.String()
case *EDNS0_PADDING:
s += "\n; PADDING: " + o.String()
}
}
return s
}
func (rr *OPT) len(off int, compression map[string]struct{}) int {
l := rr.Hdr.len(off, compression)
for _, o := range rr.Option {
l += 4 // Account for 2-byte option code and 2-byte option length.
lo, _ := o.pack()
l += len(lo)
}
return l
}
func (rr *OPT) parse(c *zlexer, origin string) *ParseError {
panic("dns: internal error: parse should never be called on OPT")
}
func (r1 *OPT) isDuplicate(r2 RR) bool { return false }
// return the old value -> delete SetVersion?
// Version returns the EDNS version used. Only zero is defined.
func (rr *OPT) Version() uint8 {
return uint8(rr.Hdr.Ttl & 0x00FF0000 >> 16)
}
// SetVersion sets the version of EDNS. This is usually zero.
func (rr *OPT) SetVersion(v uint8) {
rr.Hdr.Ttl = rr.Hdr.Ttl&0xFF00FFFF | uint32(v)<<16
}
// ExtendedRcode returns the EDNS extended RCODE field (the upper 8 bits of the TTL).
func (rr *OPT) ExtendedRcode() int {
return int(rr.Hdr.Ttl&0xFF000000>>24) << 4
}
// SetExtendedRcode sets the EDNS extended RCODE field.
//
// If the RCODE is not an extended RCODE, will reset the extended RCODE field to 0.
func (rr *OPT) SetExtendedRcode(v uint16) {
rr.Hdr.Ttl = rr.Hdr.Ttl&0x00FFFFFF | uint32(v>>4)<<24
}
// UDPSize returns the UDP buffer size.
func (rr *OPT) UDPSize() uint16 {
return rr.Hdr.Class
}
// SetUDPSize sets the UDP buffer size.
func (rr *OPT) SetUDPSize(size uint16) {
rr.Hdr.Class = size
}
// Do returns the value of the DO (DNSSEC OK) bit.
func (rr *OPT) Do() bool {
return rr.Hdr.Ttl&_DO == _DO
}
// 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 (rr *OPT) SetDo(do ...bool) {
if len(do) == 1 {
if do[0] {
rr.Hdr.Ttl |= _DO
} else {
rr.Hdr.Ttl &^= _DO
}
} else {
rr.Hdr.Ttl |= _DO
}
}
// EDNS0 defines an EDNS0 Option. An OPT RR can have multiple options appended to it.
type EDNS0 interface {
// Option returns the option code for the option.
Option() uint16
// pack returns the bytes of the option data.
pack() ([]byte, error)
// unpack sets the data as found in the buffer. Is also sets
// the length of the slice as the length of the option data.
unpack([]byte) error
// String returns the string representation of the option.
String() string
// copy returns a deep-copy of the option.
copy() EDNS0
}
// 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)
type EDNS0_NSID struct {
Code uint16 // Always EDNS0NSID
Nsid string // This string needs to be hex encoded
}
func (e *EDNS0_NSID) pack() ([]byte, error) {
h, err := hex.DecodeString(e.Nsid)
if err != nil {
return nil, err
}
return h, nil
}
// Option implements the EDNS0 interface.
func (e *EDNS0_NSID) Option() uint16 { return EDNS0NSID } // Option returns the option code.
func (e *EDNS0_NSID) unpack(b []byte) error { e.Nsid = hex.EncodeToString(b); return nil }
func (e *EDNS0_NSID) String() string { return e.Nsid }
func (e *EDNS0_NSID) copy() EDNS0 { return &EDNS0_NSID{e.Code, e.Nsid} }
// 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.
type EDNS0_SUBNET struct {
Code uint16 // Always EDNS0SUBNET
Family uint16 // 1 for IP, 2 for IP6
SourceNetmask uint8
SourceScope uint8
Address net.IP
}
// Option implements the EDNS0 interface.
func (e *EDNS0_SUBNET) Option() uint16 { return EDNS0SUBNET }
func (e *EDNS0_SUBNET) pack() ([]byte, error) {
b := make([]byte, 4)
binary.BigEndian.PutUint16(b[0:], e.Family)
b[2] = e.SourceNetmask
b[3] = e.SourceScope
switch e.Family {
case 0:
// "dig" sets AddressFamily to 0 if SourceNetmask is also 0
// We might don't need to complain either
if e.SourceNetmask != 0 {
return nil, errors.New("dns: bad address family")
}
case 1:
if e.SourceNetmask > net.IPv4len*8 {
return nil, errors.New("dns: bad netmask")
}
if len(e.Address.To4()) != net.IPv4len {
return nil, errors.New("dns: bad address")
}
ip := e.Address.To4().Mask(net.CIDRMask(int(e.SourceNetmask), net.IPv4len*8))
needLength := (e.SourceNetmask + 8 - 1) / 8 // division rounding up
b = append(b, ip[:needLength]...)
case 2:
if e.SourceNetmask > net.IPv6len*8 {
return nil, errors.New("dns: bad netmask")
}
if len(e.Address) != net.IPv6len {
return nil, errors.New("dns: bad address")
}
ip := e.Address.Mask(net.CIDRMask(int(e.SourceNetmask), net.IPv6len*8))
needLength := (e.SourceNetmask + 8 - 1) / 8 // division rounding up
b = append(b, ip[:needLength]...)
default:
return nil, errors.New("dns: bad address family")
}
return b, nil
}
func (e *EDNS0_SUBNET) unpack(b []byte) error {
if len(b) < 4 {
return ErrBuf
}
e.Family = binary.BigEndian.Uint16(b)
e.SourceNetmask = b[2]
e.SourceScope = b[3]
switch e.Family {
case 0:
// "dig" sets AddressFamily to 0 if SourceNetmask is also 0
// It's okay to accept such a packet
if e.SourceNetmask != 0 {
return errors.New("dns: bad address family")
}
e.Address = net.IPv4(0, 0, 0, 0)
case 1:
if e.SourceNetmask > net.IPv4len*8 || e.SourceScope > net.IPv4len*8 {
return errors.New("dns: bad netmask")
}
addr := make(net.IP, net.IPv4len)
copy(addr, b[4:])
e.Address = addr.To16()
case 2:
if e.SourceNetmask > net.IPv6len*8 || e.SourceScope > net.IPv6len*8 {
return errors.New("dns: bad netmask")
}
addr := make(net.IP, net.IPv6len)
copy(addr, b[4:])
e.Address = addr
default:
return errors.New("dns: bad address family")
}
return nil
}
func (e *EDNS0_SUBNET) String() (s string) {
if e.Address == nil {
s = "<nil>"
} else if e.Address.To4() != nil {
s = e.Address.String()
} else {
s = "[" + e.Address.String() + "]"
}
s += "/" + strconv.Itoa(int(e.SourceNetmask)) + "/" + strconv.Itoa(int(e.SourceScope))
return
}
func (e *EDNS0_SUBNET) copy() EDNS0 {
return &EDNS0_SUBNET{
e.Code,
e.Family,
e.SourceNetmask,
e.SourceScope,
e.Address,
}
}
// 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.
type EDNS0_COOKIE struct {
Code uint16 // Always EDNS0COOKIE
Cookie string // Hex-encoded cookie data
}
func (e *EDNS0_COOKIE) pack() ([]byte, error) {
h, err := hex.DecodeString(e.Cookie)
if err != nil {
return nil, err
}
return h, nil
}
// Option implements the EDNS0 interface.
func (e *EDNS0_COOKIE) Option() uint16 { return EDNS0COOKIE }
func (e *EDNS0_COOKIE) unpack(b []byte) error { e.Cookie = hex.EncodeToString(b); return nil }
func (e *EDNS0_COOKIE) String() string { return e.Cookie }
func (e *EDNS0_COOKIE) copy() EDNS0 { return &EDNS0_COOKIE{e.Code, e.Cookie} }
// 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
// http://files.dns-sd.org/draft-sekar-dns-ul.txt
//
// 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)
type EDNS0_UL struct {
Code uint16 // Always EDNS0UL
Lease uint32
}
// Option implements the EDNS0 interface.
func (e *EDNS0_UL) Option() uint16 { return EDNS0UL }
func (e *EDNS0_UL) String() string { return strconv.FormatUint(uint64(e.Lease), 10) }
func (e *EDNS0_UL) copy() EDNS0 { return &EDNS0_UL{e.Code, e.Lease} }
// Copied: http://golang.org/src/pkg/net/dnsmsg.go
func (e *EDNS0_UL) pack() ([]byte, error) {
b := make([]byte, 4)
binary.BigEndian.PutUint32(b, e.Lease)
return b, nil
}
func (e *EDNS0_UL) unpack(b []byte) error {
if len(b) < 4 {
return ErrBuf
}
e.Lease = binary.BigEndian.Uint32(b)
return nil
}
// 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.
type EDNS0_LLQ struct {
Code uint16 // Always EDNS0LLQ
Version uint16
Opcode uint16
Error uint16
Id uint64
LeaseLife uint32
}
// Option implements the EDNS0 interface.
func (e *EDNS0_LLQ) Option() uint16 { return EDNS0LLQ }
func (e *EDNS0_LLQ) pack() ([]byte, error) {
b := make([]byte, 18)
binary.BigEndian.PutUint16(b[0:], e.Version)
binary.BigEndian.PutUint16(b[2:], e.Opcode)
binary.BigEndian.PutUint16(b[4:], e.Error)
binary.BigEndian.PutUint64(b[6:], e.Id)
binary.BigEndian.PutUint32(b[14:], e.LeaseLife)
return b, nil
}
func (e *EDNS0_LLQ) unpack(b []byte) error {
if len(b) < 18 {
return ErrBuf
}
e.Version = binary.BigEndian.Uint16(b[0:])
e.Opcode = binary.BigEndian.Uint16(b[2:])
e.Error = binary.BigEndian.Uint16(b[4:])
e.Id = binary.BigEndian.Uint64(b[6:])
e.LeaseLife = binary.BigEndian.Uint32(b[14:])
return nil
}
func (e *EDNS0_LLQ) String() string {
s := strconv.FormatUint(uint64(e.Version), 10) + " " + strconv.FormatUint(uint64(e.Opcode), 10) +
" " + strconv.FormatUint(uint64(e.Error), 10) + " " + strconv.FormatUint(e.Id, 10) +
" " + strconv.FormatUint(uint64(e.LeaseLife), 10)
return s
}
func (e *EDNS0_LLQ) copy() EDNS0 {
return &EDNS0_LLQ{e.Code, e.Version, e.Opcode, e.Error, e.Id, e.LeaseLife}
}
// EDNS0_DUA implements the EDNS0 "DNSSEC Algorithm Understood" option. See RFC 6975.
type EDNS0_DAU struct {
Code uint16 // Always EDNS0DAU
AlgCode []uint8
}
// Option implements the EDNS0 interface.
func (e *EDNS0_DAU) Option() uint16 { return EDNS0DAU }
func (e *EDNS0_DAU) pack() ([]byte, error) { return e.AlgCode, nil }
func (e *EDNS0_DAU) unpack(b []byte) error { e.AlgCode = b; return nil }
func (e *EDNS0_DAU) String() string {
s := ""
for _, alg := range e.AlgCode {
if a, ok := AlgorithmToString[alg]; ok {
s += " " + a
} else {
s += " " + strconv.Itoa(int(alg))
}
}
return s
}
func (e *EDNS0_DAU) copy() EDNS0 { return &EDNS0_DAU{e.Code, e.AlgCode} }
// EDNS0_DHU implements the EDNS0 "DS Hash Understood" option. See RFC 6975.
type EDNS0_DHU struct {
Code uint16 // Always EDNS0DHU
AlgCode []uint8
}
// Option implements the EDNS0 interface.
func (e *EDNS0_DHU) Option() uint16 { return EDNS0DHU }
func (e *EDNS0_DHU) pack() ([]byte, error) { return e.AlgCode, nil }
func (e *EDNS0_DHU) unpack(b []byte) error { e.AlgCode = b; return nil }
func (e *EDNS0_DHU) String() string {
s := ""
for _, alg := range e.AlgCode {
if a, ok := HashToString[alg]; ok {
s += " " + a
} else {
s += " " + strconv.Itoa(int(alg))
}
}
return s
}
func (e *EDNS0_DHU) copy() EDNS0 { return &EDNS0_DHU{e.Code, e.AlgCode} }
// EDNS0_N3U implements the EDNS0 "NSEC3 Hash Understood" option. See RFC 6975.
type EDNS0_N3U struct {
Code uint16 // Always EDNS0N3U
AlgCode []uint8
}
// Option implements the EDNS0 interface.
func (e *EDNS0_N3U) Option() uint16 { return EDNS0N3U }
func (e *EDNS0_N3U) pack() ([]byte, error) { return e.AlgCode, nil }
func (e *EDNS0_N3U) unpack(b []byte) error { e.AlgCode = b; return nil }
func (e *EDNS0_N3U) String() string {
// Re-use the hash map
s := ""
for _, alg := range e.AlgCode {
if a, ok := HashToString[alg]; ok {
s += " " + a
} else {
s += " " + strconv.Itoa(int(alg))
}
}
return s
}
func (e *EDNS0_N3U) copy() EDNS0 { return &EDNS0_N3U{e.Code, e.AlgCode} }
// EDNS0_EXPIRE implementes the EDNS0 option as described in RFC 7314.
type EDNS0_EXPIRE struct {
Code uint16 // Always EDNS0EXPIRE
Expire uint32
}
// Option implements the EDNS0 interface.
func (e *EDNS0_EXPIRE) Option() uint16 { return EDNS0EXPIRE }
func (e *EDNS0_EXPIRE) String() string { return strconv.FormatUint(uint64(e.Expire), 10) }
func (e *EDNS0_EXPIRE) copy() EDNS0 { return &EDNS0_EXPIRE{e.Code, e.Expire} }
func (e *EDNS0_EXPIRE) pack() ([]byte, error) {
b := make([]byte, 4)
binary.BigEndian.PutUint32(b, e.Expire)
return b, nil
}
func (e *EDNS0_EXPIRE) unpack(b []byte) error {
if len(b) < 4 {
return ErrBuf
}
e.Expire = binary.BigEndian.Uint32(b)
return nil
}
// 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)
type EDNS0_LOCAL struct {
Code uint16
Data []byte
}
// Option implements the EDNS0 interface.
func (e *EDNS0_LOCAL) Option() uint16 { return e.Code }
func (e *EDNS0_LOCAL) String() string {
return strconv.FormatInt(int64(e.Code), 10) + ":0x" + hex.EncodeToString(e.Data)
}
func (e *EDNS0_LOCAL) copy() EDNS0 {
b := make([]byte, len(e.Data))
copy(b, e.Data)
return &EDNS0_LOCAL{e.Code, b}
}
func (e *EDNS0_LOCAL) pack() ([]byte, error) {
b := make([]byte, len(e.Data))
copied := copy(b, e.Data)
if copied != len(e.Data) {
return nil, ErrBuf
}
return b, nil
}
func (e *EDNS0_LOCAL) unpack(b []byte) error {
e.Data = make([]byte, len(b))
copied := copy(e.Data, b)
if copied != len(b) {
return ErrBuf
}
return nil
}
// EDNS0_TCP_KEEPALIVE is an EDNS0 option that instructs the server to keep
// the TCP connection alive. See RFC 7828.
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.
}
// Option implements the EDNS0 interface.
func (e *EDNS0_TCP_KEEPALIVE) Option() uint16 { return EDNS0TCPKEEPALIVE }
func (e *EDNS0_TCP_KEEPALIVE) pack() ([]byte, error) {
if e.Timeout != 0 && e.Length != 2 {
return nil, errors.New("dns: timeout specified but length is not 2")
}
if e.Timeout == 0 && e.Length != 0 {
return nil, errors.New("dns: timeout not specified but length is not 0")
}
b := make([]byte, 4+e.Length)
binary.BigEndian.PutUint16(b[0:], e.Code)
binary.BigEndian.PutUint16(b[2:], e.Length)
if e.Length == 2 {
binary.BigEndian.PutUint16(b[4:], e.Timeout)
}
return b, nil
}
func (e *EDNS0_TCP_KEEPALIVE) unpack(b []byte) error {
if len(b) < 4 {
return ErrBuf
}
e.Length = binary.BigEndian.Uint16(b[2:4])
if e.Length != 0 && e.Length != 2 {
return errors.New("dns: length mismatch, want 0/2 but got " + strconv.FormatUint(uint64(e.Length), 10))
}
if e.Length == 2 {
if len(b) < 6 {
return ErrBuf
}
e.Timeout = binary.BigEndian.Uint16(b[4:6])
}
return nil
}
func (e *EDNS0_TCP_KEEPALIVE) String() (s string) {
s = "use tcp keep-alive"
if e.Length == 0 {
s += ", timeout omitted"
} else {
s += fmt.Sprintf(", timeout %dms", e.Timeout*100)
}
return
}
func (e *EDNS0_TCP_KEEPALIVE) copy() EDNS0 { return &EDNS0_TCP_KEEPALIVE{e.Code, e.Length, e.Timeout} }
// 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.
type EDNS0_PADDING struct {
Padding []byte
}
// Option implements the EDNS0 interface.
func (e *EDNS0_PADDING) Option() uint16 { return EDNS0PADDING }
func (e *EDNS0_PADDING) pack() ([]byte, error) { return e.Padding, nil }
func (e *EDNS0_PADDING) unpack(b []byte) error { e.Padding = b; return nil }
func (e *EDNS0_PADDING) String() string { return fmt.Sprintf("%0X", e.Padding) }
func (e *EDNS0_PADDING) copy() EDNS0 {
b := make([]byte, len(e.Padding))
copy(b, e.Padding)
return &EDNS0_PADDING{b}
}
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