497 lines
12 KiB
Go
497 lines
12 KiB
Go
// Copyright 2011 Miek Gieben. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// EDNS0
|
|
//
|
|
// EDNS0 is an extension mechanism for the DNS defined in RFC 2671 and updated
|
|
// by RFC 6891. It defines a standard 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 interfaces. Currently
|
|
// only a few have been standardized: EDNS0_NSID (RFC 5001) and EDNS0_SUBNET (draft). 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.
|
|
// }
|
|
// }
|
|
package dns
|
|
|
|
import (
|
|
"encoding/hex"
|
|
"errors"
|
|
"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 (RFC5001)
|
|
EDNS0SUBNET = 0x50fa // client-subnet draft: http://tools.ietf.org/html/draft-vandergaast-edns-client-subnet-01
|
|
EDNS0DAU = 0x5 // DNSSEC Algorithm Understood
|
|
EDNS0DHU = 0x6 // DS Hash Understood
|
|
EDNS0N3U = 0x7 // NSEC3 Hash Understood
|
|
_DO = 1 << 7 // dnssec ok
|
|
)
|
|
|
|
type OPT struct {
|
|
Hdr RR_Header
|
|
Option []EDNS0 `dns:"opt"`
|
|
}
|
|
|
|
func (rr *OPT) Header() *RR_Header {
|
|
return &rr.Hdr
|
|
}
|
|
|
|
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_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()
|
|
}
|
|
}
|
|
return s
|
|
}
|
|
|
|
func (rr *OPT) len() int {
|
|
l := rr.Hdr.len()
|
|
for i := 0; i < len(rr.Option); i++ {
|
|
lo, _ := rr.Option[i].pack()
|
|
l += 2 + len(lo)
|
|
}
|
|
return l
|
|
}
|
|
|
|
func (rr *OPT) copy() RR {
|
|
return &OPT{*rr.Hdr.copyHeader(), rr.Option}
|
|
}
|
|
|
|
// 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 & 0x00FF00FFFF)
|
|
}
|
|
|
|
// 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)
|
|
}
|
|
|
|
// 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 byte(rr.Hdr.Ttl>>8)&_DO == _DO
|
|
}
|
|
|
|
// SetDo sets the DO (DNSSEC OK) bit.
|
|
func (rr *OPT) SetDo() {
|
|
b1 := byte(rr.Hdr.Ttl >> 24)
|
|
b2 := byte(rr.Hdr.Ttl >> 16)
|
|
b3 := byte(rr.Hdr.Ttl >> 8)
|
|
b4 := byte(rr.Hdr.Ttl)
|
|
b3 |= _DO // Set it
|
|
rr.Hdr.Ttl = uint32(b1)<<24 | uint32(b2)<<16 | uint32(b3)<<8 | uint32(b4)
|
|
}
|
|
|
|
// EDNS0 defines an EDNS0 Option. An OPT RR can have multiple options appended to
|
|
// it. Basic use pattern for adding an option to and OPT RR:
|
|
//
|
|
// // o is the OPT RR, e is the EDNS0 option
|
|
// o.Option = append(o.Option, e)
|
|
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)
|
|
// String returns the string representation of the option.
|
|
String() string
|
|
}
|
|
|
|
// The nsid EDNS0 option is used to retrieve some sort of nameserver
|
|
// identifier. When seding 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
|
|
// 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) Option() uint16 {
|
|
return EDNS0NSID
|
|
}
|
|
|
|
func (e *EDNS0_NSID) pack() ([]byte, error) {
|
|
h, err := hex.DecodeString(e.Nsid)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return h, nil
|
|
}
|
|
|
|
func (e *EDNS0_NSID) unpack(b []byte) {
|
|
e.Nsid = hex.EncodeToString(b)
|
|
}
|
|
|
|
func (e *EDNS0_NSID) String() string {
|
|
return string(e.Nsid)
|
|
}
|
|
|
|
// The subnet EDNS0 option is used to give the remote nameserver
|
|
// an idea of where the client lives. 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.NetMask = 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)
|
|
type EDNS0_SUBNET struct {
|
|
Code uint16 // Always EDNS0SUBNET
|
|
Family uint16 // 1 for IP, 2 for IP6
|
|
SourceNetmask uint8
|
|
SourceScope uint8
|
|
Address net.IP
|
|
}
|
|
|
|
func (e *EDNS0_SUBNET) Option() uint16 {
|
|
return EDNS0SUBNET
|
|
}
|
|
|
|
func (e *EDNS0_SUBNET) pack() ([]byte, error) {
|
|
b := make([]byte, 4)
|
|
b[0], b[1] = packUint16(e.Family)
|
|
b[2] = e.SourceNetmask
|
|
b[3] = e.SourceScope
|
|
switch e.Family {
|
|
case 1:
|
|
if e.SourceNetmask > net.IPv4len*8 {
|
|
return nil, errors.New("dns: bad netmask")
|
|
}
|
|
ip := make([]byte, net.IPv4len)
|
|
a := e.Address.To4().Mask(net.CIDRMask(int(e.SourceNetmask), net.IPv4len*8))
|
|
for i := 0; i < net.IPv4len; i++ {
|
|
if i+1 > len(e.Address) {
|
|
break
|
|
}
|
|
ip[i] = a[i]
|
|
}
|
|
needLength := e.SourceNetmask / 8
|
|
if e.SourceNetmask%8 > 0 {
|
|
needLength++
|
|
}
|
|
ip = ip[:needLength]
|
|
b = append(b, ip...)
|
|
case 2:
|
|
if e.SourceNetmask > net.IPv6len*8 {
|
|
return nil, errors.New("dns: bad netmask")
|
|
}
|
|
ip := make([]byte, net.IPv6len)
|
|
a := e.Address.Mask(net.CIDRMask(int(e.SourceNetmask), net.IPv6len*8))
|
|
for i := 0; i < net.IPv6len; i++ {
|
|
if i+1 > len(e.Address) {
|
|
break
|
|
}
|
|
ip[i] = a[i]
|
|
}
|
|
needLength := e.SourceNetmask / 8
|
|
if e.SourceNetmask%8 > 0 {
|
|
needLength++
|
|
}
|
|
ip = ip[:needLength]
|
|
b = append(b, ip...)
|
|
default:
|
|
return nil, errors.New("dns: bad address family")
|
|
}
|
|
return b, nil
|
|
}
|
|
|
|
func (e *EDNS0_SUBNET) unpack(b []byte) {
|
|
lb := len(b)
|
|
if lb < 4 {
|
|
return
|
|
}
|
|
e.Family, _ = unpackUint16(b, 0)
|
|
e.SourceNetmask = b[2]
|
|
e.SourceScope = b[3]
|
|
switch e.Family {
|
|
case 1:
|
|
addr := make([]byte, 4)
|
|
for i := 0; i < int(e.SourceNetmask/8); i++ {
|
|
if 4+i > len(b) {
|
|
break
|
|
}
|
|
addr[i] = b[4+i]
|
|
}
|
|
e.Address = net.IPv4(addr[0], addr[1], addr[2], addr[3])
|
|
case 2:
|
|
addr := make([]byte, 16)
|
|
for i := 0; i < int(e.SourceNetmask/8); i++ {
|
|
if 4+i > len(b) {
|
|
break
|
|
}
|
|
addr[i] = b[4+i]
|
|
}
|
|
e.Address = net.IP{addr[0], addr[1], addr[2], addr[3], addr[4],
|
|
addr[5], addr[6], addr[7], addr[8], addr[9], addr[10],
|
|
addr[11], addr[12], addr[13], addr[14], addr[15]}
|
|
}
|
|
return
|
|
}
|
|
|
|
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
|
|
}
|
|
|
|
// The UL (Update Lease) EDNS0 (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
|
|
}
|
|
|
|
func (e *EDNS0_UL) Option() uint16 {
|
|
return EDNS0UL
|
|
}
|
|
|
|
// Copied: http://golang.org/src/pkg/net/dnsmsg.go
|
|
func (e *EDNS0_UL) pack() ([]byte, error) {
|
|
b := make([]byte, 4)
|
|
b[0] = byte(e.Lease >> 24)
|
|
b[1] = byte(e.Lease >> 16)
|
|
b[2] = byte(e.Lease >> 8)
|
|
b[3] = byte(e.Lease)
|
|
return b, nil
|
|
}
|
|
|
|
func (e *EDNS0_UL) unpack(b []byte) {
|
|
e.Lease = uint32(b[0])<<24 | uint32(b[1])<<16 | uint32(b[2])<<8 | uint32(b[3])
|
|
}
|
|
|
|
func (e *EDNS0_UL) String() string {
|
|
return strconv.FormatUint(uint64(e.Lease), 10)
|
|
}
|
|
|
|
// 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
|
|
}
|
|
|
|
func (e *EDNS0_LLQ) Option() uint16 {
|
|
return EDNS0LLQ
|
|
}
|
|
|
|
func (e *EDNS0_LLQ) pack() ([]byte, error) {
|
|
b := make([]byte, 18)
|
|
b[0], b[1] = packUint16(e.Version)
|
|
b[2], b[3] = packUint16(e.Opcode)
|
|
b[4], b[5] = packUint16(e.Error)
|
|
b[6] = byte(e.Id >> 56)
|
|
b[7] = byte(e.Id >> 48)
|
|
b[8] = byte(e.Id >> 40)
|
|
b[9] = byte(e.Id >> 32)
|
|
b[10] = byte(e.Id >> 24)
|
|
b[11] = byte(e.Id >> 16)
|
|
b[12] = byte(e.Id >> 8)
|
|
b[13] = byte(e.Id)
|
|
b[14] = byte(e.LeaseLife >> 24)
|
|
b[15] = byte(e.LeaseLife >> 16)
|
|
b[16] = byte(e.LeaseLife >> 8)
|
|
b[17] = byte(e.LeaseLife)
|
|
return nil, nil
|
|
}
|
|
|
|
func (e *EDNS0_LLQ) unpack(b []byte) {
|
|
e.Version, _ = unpackUint16(b, 0)
|
|
e.Opcode, _ = unpackUint16(b, 2)
|
|
e.Error, _ = unpackUint16(b, 4)
|
|
e.Id = uint64(b[6])<<56 | uint64(b[6+1])<<48 | uint64(b[6+2])<<40 |
|
|
uint64(b[6+3])<<32 | uint64(b[6+4])<<24 | uint64(b[6+5])<<16 | uint64(b[6+6])<<8 | uint64(b[6+7])
|
|
e.LeaseLife = uint32(b[14])<<24 | uint32(b[14+1])<<16 | uint32(b[14+2])<<8 | uint32(b[14+3])
|
|
}
|
|
|
|
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(uint64(e.Id), 10) +
|
|
" " + strconv.FormatUint(uint64(e.LeaseLife), 10)
|
|
return s
|
|
}
|
|
|
|
type EDNS0_DAU struct {
|
|
Code uint16 // Always EDNS0DAU
|
|
AlgCode []uint8
|
|
}
|
|
|
|
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) {
|
|
e.AlgCode = b
|
|
}
|
|
|
|
func (e *EDNS0_DAU) String() string {
|
|
s := ""
|
|
for i := 0; i < len(e.AlgCode); i++ {
|
|
if a, ok := AlgorithmToString[e.AlgCode[i]]; ok {
|
|
s += " " + a
|
|
} else {
|
|
s += " " + strconv.Itoa(int(e.AlgCode[i]))
|
|
}
|
|
}
|
|
return s
|
|
|
|
}
|
|
|
|
type EDNS0_DHU struct {
|
|
Code uint16 // Always EDNS0DHU
|
|
AlgCode []uint8
|
|
}
|
|
|
|
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) {
|
|
e.AlgCode = b
|
|
}
|
|
|
|
func (e *EDNS0_DHU) String() string {
|
|
s := ""
|
|
for i := 0; i < len(e.AlgCode); i++ {
|
|
if a, ok := HashToString[e.AlgCode[i]]; ok {
|
|
s += " " + a
|
|
} else {
|
|
s += " " + strconv.Itoa(int(e.AlgCode[i]))
|
|
}
|
|
}
|
|
return s
|
|
}
|
|
|
|
type EDNS0_N3U struct {
|
|
Code uint16 // Always EDNS0N3U
|
|
AlgCode []uint8
|
|
}
|
|
|
|
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) {
|
|
e.AlgCode = b
|
|
}
|
|
|
|
func (e *EDNS0_N3U) String() string {
|
|
// Re-use the hash map
|
|
s := ""
|
|
for i := 0; i < len(e.AlgCode); i++ {
|
|
if a, ok := HashToString[e.AlgCode[i]]; ok {
|
|
s += " " + a
|
|
} else {
|
|
s += " " + strconv.Itoa(int(e.AlgCode[i]))
|
|
}
|
|
}
|
|
return s
|
|
}
|