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status-go/vendor/github.com/miekg/dns/svcb.go

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package dns
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"net"
"sort"
"strconv"
"strings"
)
// SVCBKey is the type of the keys used in the SVCB RR.
type SVCBKey uint16
// Keys defined in draft-ietf-dnsop-svcb-https-08 Section 14.3.2.
const (
SVCB_MANDATORY SVCBKey = iota
SVCB_ALPN
SVCB_NO_DEFAULT_ALPN
SVCB_PORT
SVCB_IPV4HINT
SVCB_ECHCONFIG
SVCB_IPV6HINT
SVCB_DOHPATH // draft-ietf-add-svcb-dns-02 Section 9
svcb_RESERVED SVCBKey = 65535
)
var svcbKeyToStringMap = map[SVCBKey]string{
SVCB_MANDATORY: "mandatory",
SVCB_ALPN: "alpn",
SVCB_NO_DEFAULT_ALPN: "no-default-alpn",
SVCB_PORT: "port",
SVCB_IPV4HINT: "ipv4hint",
SVCB_ECHCONFIG: "ech",
SVCB_IPV6HINT: "ipv6hint",
SVCB_DOHPATH: "dohpath",
}
var svcbStringToKeyMap = reverseSVCBKeyMap(svcbKeyToStringMap)
func reverseSVCBKeyMap(m map[SVCBKey]string) map[string]SVCBKey {
n := make(map[string]SVCBKey, len(m))
for u, s := range m {
n[s] = u
}
return n
}
// 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.
func (key SVCBKey) String() string {
if x := svcbKeyToStringMap[key]; x != "" {
return x
}
if key == svcb_RESERVED {
return ""
}
return "key" + strconv.FormatUint(uint64(key), 10)
}
// svcbStringToKey returns the numerical code of an SVCB key.
// Returns svcb_RESERVED for reserved/invalid keys.
// Accepts unassigned keys as well as experimental/private keys.
func svcbStringToKey(s string) SVCBKey {
if strings.HasPrefix(s, "key") {
a, err := strconv.ParseUint(s[3:], 10, 16)
// no leading zeros
// key shouldn't be registered
if err != nil || a == 65535 || s[3] == '0' || svcbKeyToStringMap[SVCBKey(a)] != "" {
return svcb_RESERVED
}
return SVCBKey(a)
}
if key, ok := svcbStringToKeyMap[s]; ok {
return key
}
return svcb_RESERVED
}
func (rr *SVCB) parse(c *zlexer, o string) *ParseError {
l, _ := c.Next()
i, e := strconv.ParseUint(l.token, 10, 16)
if e != nil || l.err {
return &ParseError{l.token, "bad SVCB priority", l}
}
rr.Priority = uint16(i)
c.Next() // zBlank
l, _ = c.Next() // zString
rr.Target = l.token
name, nameOk := toAbsoluteName(l.token, o)
if l.err || !nameOk {
return &ParseError{l.token, "bad SVCB Target", l}
}
rr.Target = name
// Values (if any)
l, _ = c.Next()
var xs []SVCBKeyValue
// Helps require whitespace between pairs.
// Prevents key1000="a"key1001=...
canHaveNextKey := true
for l.value != zNewline && l.value != zEOF {
switch l.value {
case zString:
if !canHaveNextKey {
// The key we can now read was probably meant to be
// a part of the last value.
return &ParseError{l.token, "bad SVCB value quotation", l}
}
// In key=value pairs, value does not have to be quoted unless value
// contains whitespace. And keys don't need to have values.
// Similarly, keys with an equality signs after them don't need values.
// l.token includes at least up to the first equality sign.
idx := strings.IndexByte(l.token, '=')
var key, value string
if idx < 0 {
// Key with no value and no equality sign
key = l.token
} else if idx == 0 {
return &ParseError{l.token, "bad SVCB key", l}
} else {
key, value = l.token[:idx], l.token[idx+1:]
if value == "" {
// We have a key and an equality sign. Maybe we have nothing
// after "=" or we have a double quote.
l, _ = c.Next()
if l.value == zQuote {
// Only needed when value ends with double quotes.
// Any value starting with zQuote ends with it.
canHaveNextKey = false
l, _ = c.Next()
switch l.value {
case zString:
// We have a value in double quotes.
value = l.token
l, _ = c.Next()
if l.value != zQuote {
return &ParseError{l.token, "SVCB unterminated value", l}
}
case zQuote:
// There's nothing in double quotes.
default:
return &ParseError{l.token, "bad SVCB value", l}
}
}
}
}
kv := makeSVCBKeyValue(svcbStringToKey(key))
if kv == nil {
return &ParseError{l.token, "bad SVCB key", l}
}
if err := kv.parse(value); err != nil {
return &ParseError{l.token, err.Error(), l}
}
xs = append(xs, kv)
case zQuote:
return &ParseError{l.token, "SVCB key can't contain double quotes", l}
case zBlank:
canHaveNextKey = true
default:
return &ParseError{l.token, "bad SVCB values", l}
}
l, _ = c.Next()
}
// "In AliasMode, records SHOULD NOT include any SvcParams, and recipients MUST
// ignore any SvcParams that are present."
// However, we don't check rr.Priority == 0 && len(xs) > 0 here
// It is the responsibility of the user of the library to check this.
// This is to encourage the fixing of the source of this error.
rr.Value = xs
return nil
}
// makeSVCBKeyValue returns an SVCBKeyValue struct with the key or nil for reserved keys.
func makeSVCBKeyValue(key SVCBKey) SVCBKeyValue {
switch key {
case SVCB_MANDATORY:
return new(SVCBMandatory)
case SVCB_ALPN:
return new(SVCBAlpn)
case SVCB_NO_DEFAULT_ALPN:
return new(SVCBNoDefaultAlpn)
case SVCB_PORT:
return new(SVCBPort)
case SVCB_IPV4HINT:
return new(SVCBIPv4Hint)
case SVCB_ECHCONFIG:
return new(SVCBECHConfig)
case SVCB_IPV6HINT:
return new(SVCBIPv6Hint)
case SVCB_DOHPATH:
return new(SVCBDoHPath)
case svcb_RESERVED:
return nil
default:
e := new(SVCBLocal)
e.KeyCode = key
return e
}
}
// SVCB RR. See RFC xxxx (https://tools.ietf.org/html/draft-ietf-dnsop-svcb-https-08).
//
// NOTE: The HTTPS/SVCB RFCs are in the draft stage.
// The API, including constants and types related to SVCBKeyValues, may
// change in future versions in accordance with the latest drafts.
type SVCB struct {
Hdr RR_Header
Priority uint16 // If zero, Value must be empty or discarded by the user of this library
Target string `dns:"domain-name"`
Value []SVCBKeyValue `dns:"pairs"`
}
// 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.
//
// NOTE: The HTTPS/SVCB RFCs are in the draft stage.
// The API, including constants and types related to SVCBKeyValues, may
// change in future versions in accordance with the latest drafts.
type HTTPS struct {
SVCB
}
func (rr *HTTPS) String() string {
return rr.SVCB.String()
}
func (rr *HTTPS) parse(c *zlexer, o string) *ParseError {
return rr.SVCB.parse(c, o)
}
// SVCBKeyValue defines a key=value pair for the SVCB RR type.
// An SVCB RR can have multiple SVCBKeyValues appended to it.
type SVCBKeyValue interface {
Key() SVCBKey // Key returns the numerical key code.
pack() ([]byte, error) // pack returns the encoded value.
unpack([]byte) error // unpack sets the value.
String() string // String returns the string representation of the value.
parse(string) error // parse sets the value to the given string representation of the value.
copy() SVCBKeyValue // copy returns a deep-copy of the pair.
len() int // len returns the length of value in the wire format.
}
// SVCBMandatory pair adds to required keys that must be interpreted for the RR
// to be functional. If ignored, the whole RRSet must be ignored.
// "port" and "no-default-alpn" are mandatory by default if present,
// so they shouldn't be included here.
//
// It is incumbent upon the user of this library to reject the RRSet if
// or avoid constructing such an RRSet that:
// - "mandatory" is included as one of the keys of mandatory
// - no key is listed multiple times in mandatory
// - all keys listed in mandatory are present
// - escape sequences are not used in mandatory
// - mandatory, when present, lists at least one key
//
// 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{dns.SVCB_ALPN}
// s.Value = append(s.Value, e)
// t := new(dns.SVCBAlpn)
// t.Alpn = []string{"xmpp-client"}
// s.Value = append(s.Value, t)
type SVCBMandatory struct {
Code []SVCBKey
}
func (*SVCBMandatory) Key() SVCBKey { return SVCB_MANDATORY }
func (s *SVCBMandatory) String() string {
str := make([]string, len(s.Code))
for i, e := range s.Code {
str[i] = e.String()
}
return strings.Join(str, ",")
}
func (s *SVCBMandatory) pack() ([]byte, error) {
codes := cloneSlice(s.Code)
sort.Slice(codes, func(i, j int) bool {
return codes[i] < codes[j]
})
b := make([]byte, 2*len(codes))
for i, e := range codes {
binary.BigEndian.PutUint16(b[2*i:], uint16(e))
}
return b, nil
}
func (s *SVCBMandatory) unpack(b []byte) error {
if len(b)%2 != 0 {
return errors.New("dns: svcbmandatory: value length is not a multiple of 2")
}
codes := make([]SVCBKey, 0, len(b)/2)
for i := 0; i < len(b); i += 2 {
// We assume strictly increasing order.
codes = append(codes, SVCBKey(binary.BigEndian.Uint16(b[i:])))
}
s.Code = codes
return nil
}
func (s *SVCBMandatory) parse(b string) error {
str := strings.Split(b, ",")
codes := make([]SVCBKey, 0, len(str))
for _, e := range str {
codes = append(codes, svcbStringToKey(e))
}
s.Code = codes
return nil
}
func (s *SVCBMandatory) len() int {
return 2 * len(s.Code)
}
func (s *SVCBMandatory) copy() SVCBKeyValue {
return &SVCBMandatory{cloneSlice(s.Code)}
}
// SVCBAlpn pair is used to list supported connection protocols.
// The user of this library must ensure that at least one protocol is listed when alpn is present.
// 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(h.Value, e)
type SVCBAlpn struct {
Alpn []string
}
func (*SVCBAlpn) Key() SVCBKey { return SVCB_ALPN }
func (s *SVCBAlpn) String() string {
// An ALPN value is a comma-separated list of values, each of which can be
// an arbitrary binary value. In order to allow parsing, the comma and
// backslash characters are themselves escaped.
//
// However, this escaping is done in addition to the normal escaping which
// happens in zone files, meaning that these values must be
// double-escaped. This looks terrible, so if you see a never-ending
// sequence of backslash in a zone file this may be why.
//
// https://datatracker.ietf.org/doc/html/draft-ietf-dnsop-svcb-https-08#appendix-A.1
var str strings.Builder
for i, alpn := range s.Alpn {
// 4*len(alpn) is the worst case where we escape every character in the alpn as \123, plus 1 byte for the ',' separating the alpn from others
str.Grow(4*len(alpn) + 1)
if i > 0 {
str.WriteByte(',')
}
for j := 0; j < len(alpn); j++ {
e := alpn[j]
if ' ' > e || e > '~' {
str.WriteString(escapeByte(e))
continue
}
switch e {
// We escape a few characters which may confuse humans or parsers.
case '"', ';', ' ':
str.WriteByte('\\')
str.WriteByte(e)
// The comma and backslash characters themselves must be
// doubly-escaped. We use `\\` for the first backslash and
// the escaped numeric value for the other value. We especially
// don't want a comma in the output.
case ',':
str.WriteString(`\\\044`)
case '\\':
str.WriteString(`\\\092`)
default:
str.WriteByte(e)
}
}
}
return str.String()
}
func (s *SVCBAlpn) pack() ([]byte, error) {
// Liberally estimate the size of an alpn as 10 octets
b := make([]byte, 0, 10*len(s.Alpn))
for _, e := range s.Alpn {
if e == "" {
return nil, errors.New("dns: svcbalpn: empty alpn-id")
}
if len(e) > 255 {
return nil, errors.New("dns: svcbalpn: alpn-id too long")
}
b = append(b, byte(len(e)))
b = append(b, e...)
}
return b, nil
}
func (s *SVCBAlpn) unpack(b []byte) error {
// Estimate the size of the smallest alpn as 4 bytes
alpn := make([]string, 0, len(b)/4)
for i := 0; i < len(b); {
length := int(b[i])
i++
if i+length > len(b) {
return errors.New("dns: svcbalpn: alpn array overflowing")
}
alpn = append(alpn, string(b[i:i+length]))
i += length
}
s.Alpn = alpn
return nil
}
func (s *SVCBAlpn) parse(b string) error {
if len(b) == 0 {
s.Alpn = []string{}
return nil
}
alpn := []string{}
a := []byte{}
for p := 0; p < len(b); {
c, q := nextByte(b, p)
if q == 0 {
return errors.New("dns: svcbalpn: unterminated escape")
}
p += q
// If we find a comma, we have finished reading an alpn.
if c == ',' {
if len(a) == 0 {
return errors.New("dns: svcbalpn: empty protocol identifier")
}
alpn = append(alpn, string(a))
a = []byte{}
continue
}
// If it's a backslash, we need to handle a comma-separated list.
if c == '\\' {
dc, dq := nextByte(b, p)
if dq == 0 {
return errors.New("dns: svcbalpn: unterminated escape decoding comma-separated list")
}
if dc != '\\' && dc != ',' {
return errors.New("dns: svcbalpn: bad escaped character decoding comma-separated list")
}
p += dq
c = dc
}
a = append(a, c)
}
// Add the final alpn.
if len(a) == 0 {
return errors.New("dns: svcbalpn: last protocol identifier empty")
}
s.Alpn = append(alpn, string(a))
return nil
}
func (s *SVCBAlpn) len() int {
var l int
for _, e := range s.Alpn {
l += 1 + len(e)
}
return l
}
func (s *SVCBAlpn) copy() SVCBKeyValue {
return &SVCBAlpn{cloneSlice(s.Alpn)}
}
// SVCBNoDefaultAlpn pair signifies no support for default connection protocols.
// Should be used in conjunction with alpn.
// Basic use pattern for creating a no-default-alpn option:
//
// s := &dns.SVCB{Hdr: dns.RR_Header{Name: ".", Rrtype: dns.TypeSVCB, Class: dns.ClassINET}}
// t := new(dns.SVCBAlpn)
// t.Alpn = []string{"xmpp-client"}
// s.Value = append(s.Value, t)
// e := new(dns.SVCBNoDefaultAlpn)
// s.Value = append(s.Value, e)
type SVCBNoDefaultAlpn struct{}
func (*SVCBNoDefaultAlpn) Key() SVCBKey { return SVCB_NO_DEFAULT_ALPN }
func (*SVCBNoDefaultAlpn) copy() SVCBKeyValue { return &SVCBNoDefaultAlpn{} }
func (*SVCBNoDefaultAlpn) pack() ([]byte, error) { return []byte{}, nil }
func (*SVCBNoDefaultAlpn) String() string { return "" }
func (*SVCBNoDefaultAlpn) len() int { return 0 }
func (*SVCBNoDefaultAlpn) unpack(b []byte) error {
if len(b) != 0 {
return errors.New("dns: svcbnodefaultalpn: no-default-alpn must have no value")
}
return nil
}
func (*SVCBNoDefaultAlpn) parse(b string) error {
if b != "" {
return errors.New("dns: svcbnodefaultalpn: no-default-alpn must have no value")
}
return nil
}
// 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)
type SVCBPort struct {
Port uint16
}
func (*SVCBPort) Key() SVCBKey { return SVCB_PORT }
func (*SVCBPort) len() int { return 2 }
func (s *SVCBPort) String() string { return strconv.FormatUint(uint64(s.Port), 10) }
func (s *SVCBPort) copy() SVCBKeyValue { return &SVCBPort{s.Port} }
func (s *SVCBPort) unpack(b []byte) error {
if len(b) != 2 {
return errors.New("dns: svcbport: port length is not exactly 2 octets")
}
s.Port = binary.BigEndian.Uint16(b)
return nil
}
func (s *SVCBPort) pack() ([]byte, error) {
b := make([]byte, 2)
binary.BigEndian.PutUint16(b, s.Port)
return b, nil
}
func (s *SVCBPort) parse(b string) error {
port, err := strconv.ParseUint(b, 10, 16)
if err != nil {
return errors.New("dns: svcbport: port out of range")
}
s.Port = uint16(port)
return nil
}
// 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)
type SVCBIPv4Hint struct {
Hint []net.IP
}
func (*SVCBIPv4Hint) Key() SVCBKey { return SVCB_IPV4HINT }
func (s *SVCBIPv4Hint) len() int { return 4 * len(s.Hint) }
func (s *SVCBIPv4Hint) pack() ([]byte, error) {
b := make([]byte, 0, 4*len(s.Hint))
for _, e := range s.Hint {
x := e.To4()
if x == nil {
return nil, errors.New("dns: svcbipv4hint: expected ipv4, hint is ipv6")
}
b = append(b, x...)
}
return b, nil
}
func (s *SVCBIPv4Hint) unpack(b []byte) error {
if len(b) == 0 || len(b)%4 != 0 {
return errors.New("dns: svcbipv4hint: ipv4 address byte array length is not a multiple of 4")
}
b = cloneSlice(b)
x := make([]net.IP, 0, len(b)/4)
for i := 0; i < len(b); i += 4 {
x = append(x, net.IP(b[i:i+4]))
}
s.Hint = x
return nil
}
func (s *SVCBIPv4Hint) String() string {
str := make([]string, len(s.Hint))
for i, e := range s.Hint {
x := e.To4()
if x == nil {
return "<nil>"
}
str[i] = x.String()
}
return strings.Join(str, ",")
}
func (s *SVCBIPv4Hint) parse(b string) error {
if strings.Contains(b, ":") {
return errors.New("dns: svcbipv4hint: expected ipv4, got ipv6")
}
str := strings.Split(b, ",")
dst := make([]net.IP, len(str))
for i, e := range str {
ip := net.ParseIP(e).To4()
if ip == nil {
return errors.New("dns: svcbipv4hint: bad ip")
}
dst[i] = ip
}
s.Hint = dst
return nil
}
func (s *SVCBIPv4Hint) copy() SVCBKeyValue {
hint := make([]net.IP, len(s.Hint))
for i, ip := range s.Hint {
hint[i] = cloneSlice(ip)
}
return &SVCBIPv4Hint{Hint: hint}
}
// SVCBECHConfig pair contains the ECHConfig structure defined in draft-ietf-tls-esni [RFC xxxx].
// Basic use pattern for creating an ech 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)
type SVCBECHConfig struct {
ECH []byte // Specifically ECHConfigList including the redundant length prefix
}
func (*SVCBECHConfig) Key() SVCBKey { return SVCB_ECHCONFIG }
func (s *SVCBECHConfig) String() string { return toBase64(s.ECH) }
func (s *SVCBECHConfig) len() int { return len(s.ECH) }
func (s *SVCBECHConfig) pack() ([]byte, error) {
return cloneSlice(s.ECH), nil
}
func (s *SVCBECHConfig) copy() SVCBKeyValue {
return &SVCBECHConfig{cloneSlice(s.ECH)}
}
func (s *SVCBECHConfig) unpack(b []byte) error {
s.ECH = cloneSlice(b)
return nil
}
func (s *SVCBECHConfig) parse(b string) error {
x, err := fromBase64([]byte(b))
if err != nil {
return errors.New("dns: svcbech: bad base64 ech")
}
s.ECH = x
return nil
}
// 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)
type SVCBIPv6Hint struct {
Hint []net.IP
}
func (*SVCBIPv6Hint) Key() SVCBKey { return SVCB_IPV6HINT }
func (s *SVCBIPv6Hint) len() int { return 16 * len(s.Hint) }
func (s *SVCBIPv6Hint) pack() ([]byte, error) {
b := make([]byte, 0, 16*len(s.Hint))
for _, e := range s.Hint {
if len(e) != net.IPv6len || e.To4() != nil {
return nil, errors.New("dns: svcbipv6hint: expected ipv6, hint is ipv4")
}
b = append(b, e...)
}
return b, nil
}
func (s *SVCBIPv6Hint) unpack(b []byte) error {
if len(b) == 0 || len(b)%16 != 0 {
return errors.New("dns: svcbipv6hint: ipv6 address byte array length not a multiple of 16")
}
b = cloneSlice(b)
x := make([]net.IP, 0, len(b)/16)
for i := 0; i < len(b); i += 16 {
ip := net.IP(b[i : i+16])
if ip.To4() != nil {
return errors.New("dns: svcbipv6hint: expected ipv6, got ipv4")
}
x = append(x, ip)
}
s.Hint = x
return nil
}
func (s *SVCBIPv6Hint) String() string {
str := make([]string, len(s.Hint))
for i, e := range s.Hint {
if x := e.To4(); x != nil {
return "<nil>"
}
str[i] = e.String()
}
return strings.Join(str, ",")
}
func (s *SVCBIPv6Hint) parse(b string) error {
str := strings.Split(b, ",")
dst := make([]net.IP, len(str))
for i, e := range str {
ip := net.ParseIP(e)
if ip == nil {
return errors.New("dns: svcbipv6hint: bad ip")
}
if ip.To4() != nil {
return errors.New("dns: svcbipv6hint: expected ipv6, got ipv4-mapped-ipv6")
}
dst[i] = ip
}
s.Hint = dst
return nil
}
func (s *SVCBIPv6Hint) copy() SVCBKeyValue {
hint := make([]net.IP, len(s.Hint))
for i, ip := range s.Hint {
hint[i] = cloneSlice(ip)
}
return &SVCBIPv6Hint{Hint: hint}
}
// SVCBDoHPath pair is used to indicate the URI template that the
// clients may use to construct a DNS over HTTPS URI.
//
// See RFC xxxx (https://datatracker.ietf.org/doc/html/draft-ietf-add-svcb-dns-02)
// and RFC yyyy (https://datatracker.ietf.org/doc/html/draft-ietf-add-ddr-06).
//
// A basic example of using the dohpath option together with the alpn
// option to indicate support for DNS over HTTPS on a certain path:
//
// s := new(dns.SVCB)
// s.Hdr = dns.RR_Header{Name: ".", Rrtype: dns.TypeSVCB, Class: dns.ClassINET}
// e := new(dns.SVCBAlpn)
// e.Alpn = []string{"h2", "h3"}
// p := new(dns.SVCBDoHPath)
// p.Template = "/dns-query{?dns}"
// s.Value = append(s.Value, e, p)
//
// The parsing currently doesn't validate that Template is a valid
// RFC 6570 URI template.
type SVCBDoHPath struct {
Template string
}
func (*SVCBDoHPath) Key() SVCBKey { return SVCB_DOHPATH }
func (s *SVCBDoHPath) String() string { return svcbParamToStr([]byte(s.Template)) }
func (s *SVCBDoHPath) len() int { return len(s.Template) }
func (s *SVCBDoHPath) pack() ([]byte, error) { return []byte(s.Template), nil }
func (s *SVCBDoHPath) unpack(b []byte) error {
s.Template = string(b)
return nil
}
func (s *SVCBDoHPath) parse(b string) error {
template, err := svcbParseParam(b)
if err != nil {
return fmt.Errorf("dns: svcbdohpath: %w", err)
}
s.Template = string(template)
return nil
}
func (s *SVCBDoHPath) copy() SVCBKeyValue {
return &SVCBDoHPath{
Template: s.Template,
}
}
// 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)
type SVCBLocal struct {
KeyCode SVCBKey // Never 65535 or any assigned keys.
Data []byte // All byte sequences are allowed.
}
func (s *SVCBLocal) Key() SVCBKey { return s.KeyCode }
func (s *SVCBLocal) String() string { return svcbParamToStr(s.Data) }
func (s *SVCBLocal) pack() ([]byte, error) { return cloneSlice(s.Data), nil }
func (s *SVCBLocal) len() int { return len(s.Data) }
func (s *SVCBLocal) unpack(b []byte) error {
s.Data = cloneSlice(b)
return nil
}
func (s *SVCBLocal) parse(b string) error {
data, err := svcbParseParam(b)
if err != nil {
return fmt.Errorf("dns: svcblocal: svcb private/experimental key %w", err)
}
s.Data = data
return nil
}
func (s *SVCBLocal) copy() SVCBKeyValue {
return &SVCBLocal{s.KeyCode, cloneSlice(s.Data)}
}
func (rr *SVCB) String() string {
s := rr.Hdr.String() +
strconv.Itoa(int(rr.Priority)) + " " +
sprintName(rr.Target)
for _, e := range rr.Value {
s += " " + e.Key().String() + "=\"" + e.String() + "\""
}
return s
}
// areSVCBPairArraysEqual checks if SVCBKeyValue arrays are equal after sorting their
// copies. arrA and arrB have equal lengths, otherwise zduplicate.go wouldn't call this function.
func areSVCBPairArraysEqual(a []SVCBKeyValue, b []SVCBKeyValue) bool {
a = cloneSlice(a)
b = cloneSlice(b)
sort.Slice(a, func(i, j int) bool { return a[i].Key() < a[j].Key() })
sort.Slice(b, func(i, j int) bool { return b[i].Key() < b[j].Key() })
for i, e := range a {
if e.Key() != b[i].Key() {
return false
}
b1, err1 := e.pack()
b2, err2 := b[i].pack()
if err1 != nil || err2 != nil || !bytes.Equal(b1, b2) {
return false
}
}
return true
}
// svcbParamStr converts the value of an SVCB parameter into a DNS presentation-format string.
func svcbParamToStr(s []byte) string {
var str strings.Builder
str.Grow(4 * len(s))
for _, e := range s {
if ' ' <= e && e <= '~' {
switch e {
case '"', ';', ' ', '\\':
str.WriteByte('\\')
str.WriteByte(e)
default:
str.WriteByte(e)
}
} else {
str.WriteString(escapeByte(e))
}
}
return str.String()
}
// svcbParseParam parses a DNS presentation-format string into an SVCB parameter value.
func svcbParseParam(b string) ([]byte, error) {
data := make([]byte, 0, len(b))
for i := 0; i < len(b); {
if b[i] != '\\' {
data = append(data, b[i])
i++
continue
}
if i+1 == len(b) {
return nil, errors.New("escape unterminated")
}
if isDigit(b[i+1]) {
if i+3 < len(b) && isDigit(b[i+2]) && isDigit(b[i+3]) {
a, err := strconv.ParseUint(b[i+1:i+4], 10, 8)
if err == nil {
i += 4
data = append(data, byte(a))
continue
}
}
return nil, errors.New("bad escaped octet")
} else {
data = append(data, b[i+1])
i += 2
}
}
return data, nil
}
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