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feat: ICANN resolver support #471

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Merged
agaffney merged 1 commit into from
Dec 16, 2025
Merged

feat: ICANN resolver support #471

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15 changes: 15 additions & 0 deletions internal/config/config.go
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
package config

import (
_ "embed"
"fmt"
"os"
"strings"
Expand Down Expand Up @@ -36,6 +37,8 @@ type DnsConfig struct {
ListenPort uint `yaml:"port" envconfig:"DNS_LISTEN_PORT"`
ListenTlsPort uint `yaml:"tlsPort" envconfig:"DNS_LISTEN_TLS_PORT"`
RecursionEnabled bool `yaml:"recursionEnabled" envconfig:"DNS_RECURSION"`
RootHints string `yaml:"rootHints" envconfig:"DNS_ROOT_HINTS"`
RootHintsFile string `yaml:"rootHintsFile" envconfig:"DNS_ROOT_HINTS_FILE"`
FallbackServers []string `yaml:"fallbackServers" envconfig:"DNS_FALLBACK_SERVERS"`
}

Expand Down Expand Up @@ -69,6 +72,9 @@ type TlsConfig struct {
KeyFilePath string `yaml:"keyFilePath" envconfig:"TLS_KEY_FILE_PATH"`
}

//go:embed named.root
var defaultRootHints []byte

// Singleton config instance with default values
var globalConfig = &Config{
Logging: LoggingConfig{
Expand All @@ -78,6 +84,7 @@ var globalConfig = &Config{
ListenAddress: "",
ListenPort: 8053,
ListenTlsPort: 8853,
RootHints: string(defaultRootHints),
// hdns.io
FallbackServers: []string{
"103.196.38.38",
Expand Down Expand Up @@ -170,6 +177,14 @@ func Load(configFile string) (*Config, error) {
globalConfig.Indexer.InterceptSlot = interceptSlot
}
}
// Load root hints
if globalConfig.Dns.RootHintsFile != "" {
hintsContent, err := os.ReadFile(globalConfig.Dns.RootHintsFile)
if err != nil {
return nil, err
}
globalConfig.Dns.RootHints = string(hintsContent)
}
return globalConfig, nil
}

Expand Down
92 changes: 92 additions & 0 deletions internal/config/named.root
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Original file line number Diff line number Diff line change
@@ -0,0 +1,92 @@
; This file holds the information on root name servers needed to
; initialize cache of Internet domain name servers
; (e.g. reference this file in the "cache . <file>"
; configuration file of BIND domain name servers).
;
; This file is made available by InterNIC
; under anonymous FTP as
; file /domain/named.cache
; on server FTP.INTERNIC.NET
; -OR- RS.INTERNIC.NET
;
; last update: November 20, 2025
; related version of root zone: 2025112001
;
; FORMERLY NS.INTERNIC.NET
;
. 3600000 NS A.ROOT-SERVERS.NET.
A.ROOT-SERVERS.NET. 3600000 A 198.41.0.4
A.ROOT-SERVERS.NET. 3600000 AAAA 2001:503:ba3e::2:30
;
; FORMERLY NS1.ISI.EDU
;
. 3600000 NS B.ROOT-SERVERS.NET.
B.ROOT-SERVERS.NET. 3600000 A 170.247.170.2
B.ROOT-SERVERS.NET. 3600000 AAAA 2801:1b8:10::b
;
; FORMERLY C.PSI.NET
;
. 3600000 NS C.ROOT-SERVERS.NET.
C.ROOT-SERVERS.NET. 3600000 A 192.33.4.12
C.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:2::c
;
; FORMERLY TERP.UMD.EDU
;
. 3600000 NS D.ROOT-SERVERS.NET.
D.ROOT-SERVERS.NET. 3600000 A 199.7.91.13
D.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:2d::d
;
; FORMERLY NS.NASA.GOV
;
. 3600000 NS E.ROOT-SERVERS.NET.
E.ROOT-SERVERS.NET. 3600000 A 192.203.230.10
E.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:a8::e
;
; FORMERLY NS.ISC.ORG
;
. 3600000 NS F.ROOT-SERVERS.NET.
F.ROOT-SERVERS.NET. 3600000 A 192.5.5.241
F.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:2f::f
;
; FORMERLY NS.NIC.DDN.MIL
;
. 3600000 NS G.ROOT-SERVERS.NET.
G.ROOT-SERVERS.NET. 3600000 A 192.112.36.4
G.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:12::d0d
;
; FORMERLY AOS.ARL.ARMY.MIL
;
. 3600000 NS H.ROOT-SERVERS.NET.
H.ROOT-SERVERS.NET. 3600000 A 198.97.190.53
H.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:1::53
;
; FORMERLY NIC.NORDU.NET
;
. 3600000 NS I.ROOT-SERVERS.NET.
I.ROOT-SERVERS.NET. 3600000 A 192.36.148.17
I.ROOT-SERVERS.NET. 3600000 AAAA 2001:7fe::53
;
; OPERATED BY VERISIGN, INC.
;
. 3600000 NS J.ROOT-SERVERS.NET.
J.ROOT-SERVERS.NET. 3600000 A 192.58.128.30
J.ROOT-SERVERS.NET. 3600000 AAAA 2001:503:c27::2:30
;
; OPERATED BY RIPE NCC
;
. 3600000 NS K.ROOT-SERVERS.NET.
K.ROOT-SERVERS.NET. 3600000 A 193.0.14.129
K.ROOT-SERVERS.NET. 3600000 AAAA 2001:7fd::1
;
; OPERATED BY ICANN
;
. 3600000 NS L.ROOT-SERVERS.NET.
L.ROOT-SERVERS.NET. 3600000 A 199.7.83.42
L.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:9f::42
;
; OPERATED BY WIDE
;
. 3600000 NS M.ROOT-SERVERS.NET.
M.ROOT-SERVERS.NET. 3600000 A 202.12.27.33
M.ROOT-SERVERS.NET. 3600000 AAAA 2001:dc3::35
; End of file
48 changes: 46 additions & 2 deletions internal/dns/dns.go
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,8 @@ var metricQueryTotal = promauto.NewCounter(prometheus.CounterOpts{
Help: "total DNS queries handled",
})

var rootHints map[uint16]map[string][]dns.RR

func Start() error {
cfg := config.GetConfig()
listenAddr := fmt.Sprintf(
Expand All @@ -40,6 +42,10 @@ func Start() error {
slog.Info(
"starting DNS listener on " + listenAddr,
)
// Load root hints
if err := loadRootHints(cfg); err != nil {
return err
}
// Setup handler
dns.HandleFunc(".", handleQuery)
// UDP listener
Expand Down Expand Up @@ -76,6 +82,28 @@ func Start() error {
return nil
}

func loadRootHints(cfg *config.Config) error {
rootHints = make(map[uint16]map[string][]dns.RR)
for line := range strings.SplitSeq(cfg.Dns.RootHints, "\n") {
tmpRR, err := dns.NewRR(line)
if err != nil {
return fmt.Errorf("load root hints: %w", err)
}
if tmpRR == nil {
continue
}
rrType := tmpRR.Header().Rrtype
if _, ok := rootHints[rrType]; !ok {
rootHints[rrType] = make(map[string][]dns.RR)
}
rootHints[rrType][tmpRR.Header().Name] = append(
rootHints[rrType][tmpRR.Header().Name],
tmpRR,
)
}
return nil
}

func startListener(server *dns.Server) {
if err := server.ListenAndServe(); err != nil {
slog.Error(
Expand Down Expand Up @@ -492,8 +520,24 @@ func findNameserversForDomain(
return dns.Fqdn(lookupDomainName), ret, nil
}
}

return "", nil, nil
// Return root hints
ret := map[string][]net.IP{}
if rootHints != nil && rootHints[dns.TypeNS] != nil {
for _, tmpRecord := range rootHints[dns.TypeNS][`.`] {
nsRec := tmpRecord.(*dns.NS).Ns
if rootHints[dns.TypeA] != nil {
for _, aRecord := range rootHints[dns.TypeA][nsRec] {
ret[nsRec] = append(ret[nsRec], aRecord.(*dns.A).A)
}
}
if rootHints[dns.TypeAAAA] != nil {
for _, aaaaRecord := range rootHints[dns.TypeAAAA][nsRec] {
ret[nsRec] = append(ret[nsRec], aaaaRecord.(*dns.AAAA).AAAA)
}
}
}
}
return `.`, ret, nil
}

func getNameserversFromResponse(msg *dns.Msg) map[string][]net.IP {
Expand Down