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Add SVCB dohpath key #1359

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merged 3 commits into from Apr 12, 2022
Merged

Add SVCB dohpath key #1359

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8a162bb
Add SVCB dohpath key
ainar-g Apr 11, 2022
826b058
Fix template length, docs; reverse some changes
ainar-g Apr 12, 2022
15bc190
Remove incorrect validations; improve docs
ainar-g Apr 12, 2022
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2 changes: 2 additions & 0 deletions parse_test.go
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Expand Up @@ -1652,6 +1652,8 @@ func TestParseSVCB(t *testing.T) {
`example.com. SVCB 16 foo.example.org. alpn=h2,h3-19 mandatory=ipv4hint,alpn ipv4hint=192.0.2.1`: `example.com. 3600 IN SVCB 16 foo.example.org. alpn="h2,h3-19" mandatory="ipv4hint,alpn" ipv4hint="192.0.2.1"`,
`example.com. SVCB 16 foo.example.org. alpn="f\\\\oo\\,bar,h2"`: `example.com. 3600 IN SVCB 16 foo.example.org. alpn="f\\\\oo\\,bar,h2"`,
`example.com. SVCB 16 foo.example.org. alpn=f\\\092oo\092,bar,h2`: `example.com. 3600 IN SVCB 16 foo.example.org. alpn="f\\\092oo\092,bar,h2"`,
// From draft-ietf-add-ddr-06
`_dns.example.net. SVCB 1 example.net. alpn=h2 dohpath=/dns-query{?dns}`: `_dns.example.net. 3600 IN SVCB 1 example.net. alpn="h2" dohpath="/dns-query{?dns}"`,
}
for s, o := range svcbs {
rr, err := NewRR(s)
Expand Down
78 changes: 71 additions & 7 deletions svcb.go
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Expand Up @@ -13,7 +13,8 @@ import (
// 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.
// Keys defined in draft-ietf-dnsop-svcb-https-08 Section 14.3.2
// and draft-ietf-add-svcb-dns-02 Section 9.
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const (
SVCB_MANDATORY SVCBKey = iota
SVCB_ALPN
Expand All @@ -22,23 +23,28 @@ const (
SVCB_IPV4HINT
SVCB_ECHCONFIG
SVCB_IPV6HINT
SVCB_DOHPATH
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svcb_RESERVED SVCBKey = 65535
)

var svcbKeyToStringMap = map[SVCBKey]string{
// SVCBKeyToString is a map of strings for each SVCB key.
var SVCBKeyToString = 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)
// StringToSVCBKey is the reverse of SVCBKeyToString, needed for string
// parsing.
var StringToSVCBKey = reverseSVCBKey(SVCBKeyToString)
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func reverseSVCBKeyMap(m map[SVCBKey]string) map[string]SVCBKey {
func reverseSVCBKey(m map[SVCBKey]string) map[string]SVCBKey {
n := make(map[string]SVCBKey, len(m))
for u, s := range m {
n[s] = u
Expand All @@ -50,7 +56,7 @@ func reverseSVCBKeyMap(m map[SVCBKey]string) map[string]SVCBKey {
// 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 != "" {
if x := SVCBKeyToString[key]; x != "" {
return x
}
if key == svcb_RESERVED {
Expand All @@ -67,12 +73,12 @@ func svcbStringToKey(s string) SVCBKey {
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)] != "" {
if err != nil || a == 65535 || s[3] == '0' || SVCBKeyToString[SVCBKey(a)] != "" {
return svcb_RESERVED
}
return SVCBKey(a)
}
if key, ok := svcbStringToKeyMap[s]; ok {
if key, ok := StringToSVCBKey[s]; ok {
return key
}
return svcb_RESERVED
Expand Down Expand Up @@ -196,6 +202,8 @@ func makeSVCBKeyValue(key SVCBKey) SVCBKeyValue {
return new(SVCBECHConfig)
case SVCB_IPV6HINT:
return new(SVCBIPv6Hint)
case SVCB_DOHPATH:
return new(SVCBDoHPath)
case svcb_RESERVED:
return nil
default:
Expand Down Expand Up @@ -669,6 +677,62 @@ func (s *SVCBIPv6Hint) copy() SVCBKeyValue {
}
}

// 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).
//
// Basic use pattern for using the dohpath option together with an alpn
// option:
//
// 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"}
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// p := new(dns.SVCBDoHPath)
// p.Template = "/dns-query{?dns}"
// s.Value = append(s.Value, e, p)
//
// The parsing currently only validates the length of Template.
// It doesn't validate that Template is a valid RFC 6570 URI template.
type SVCBDoHPath struct {
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Template string
}

func (*SVCBDoHPath) Key() SVCBKey { return SVCB_DOHPATH }
func (s *SVCBDoHPath) len() int { return len(s.Template) }

func (s *SVCBDoHPath) pack() ([]byte, error) {
if len(s.Template) > 255 {
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return nil, errors.New("dns: svcbdohpath: template too long")
}
return []byte(s.Template), nil
}

func (s *SVCBDoHPath) unpack(b []byte) error {
s.Template = string(b)
return nil
}

func (s *SVCBDoHPath) String() string {
return s.Template
}

func (s *SVCBDoHPath) parse(b string) error {
if len(b) > 255 {
return errors.New("dns: svcbdohpath: template too long")
}
s.Template = b
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:
Expand Down
1 change: 1 addition & 0 deletions svcb_test.go
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Expand Up @@ -18,6 +18,7 @@ func TestSVCB(t *testing.T) {
{`no-default-alpn`, ``},
{`ipv6hint`, `1::4:4:4:4,1::3:3:3:3`},
{`ech`, `YUdWc2JHOD0=`},
{`dohpath`, `/dns-query{?dns}`},
{`key65000`, `4\ 3`},
{`key65001`, `\"\ `},
{`key65002`, ``},
Expand Down