niklas/cool-dns
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Niklas 2020-12-21 22:43:07 +01:00
commit 99568644d1
5 changed files with 271 additions and 0 deletions
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17
config.yml Normal file
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zones:
- zone: example.com.
file: zonefile.txt
- zone: example.com.
file: zonefile.txt
acl:
- vpn
acl:
- name: vpn
range: 10.0.0.0/24
forward:
alc:
- vpn

205
coolDns.go Normal file
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package main
import (
"io/ioutil"
"log"
"os"
"os/signal"
"strconv"
"syscall"
"github.com/miekg/dns"
"gopkg.in/yaml.v3"
)
type zone struct {
zone string
rr rrMap
acl []string
}
type rrMap map[uint16]map[string][]dns.RR
type config struct {
Zones []configZone `yaml:"zones"`
ACL []configACL `yaml:"acl"`
Forward configForward `yaml:"forward"`
}
type configForward struct {
ACL []string `yaml:"acl"`
}
type configACL struct {
Name string `yaml:"name"`
IPRange string `yaml:"range"`
}
type configZone struct {
Zone string `yaml:"zone"`
File string `yaml:"file"`
ACL []string `yaml:"acl"`
}
func loadConfig() (*config, error) {
file, err := ioutil.ReadFile("config.yml")
if err != nil {
return nil, err
}
var loadedConfig config
err = yaml.Unmarshal(file, &loadedConfig)
if err != nil {
return nil, err
}
return &loadedConfig, nil
}
func loadZones(configZones []configZone) ([]zone, error) {
zones := make([]zone, 0)
for _, z := range configZones {
rrs, err := loadZonefile(z.File)
if err != nil {
return nil, err
}
zones = append(zones, zone{
zone: z.Zone,
rr: createRRMap(rrs),
})
log.Printf("Loaded zone %s\n", z.Zone)
}
return zones, nil
}
func createRRMap(rrs []dns.RR) rrMap {
rrMap := make(rrMap)
for _, rr := range rrs {
if rrMap[rr.Header().Rrtype] == nil {
rrMap[rr.Header().Rrtype] = make(map[string][]dns.RR)
}
if rrMap[rr.Header().Rrtype][rr.Header().Name] == nil {
rrMap[rr.Header().Rrtype][rr.Header().Name] = make([]dns.RR, 0)
}
rrMap[rr.Header().Rrtype][rr.Header().Name] = append(rrMap[rr.Header().Rrtype][rr.Header().Name], rr)
}
return rrMap
}
func loadZonefile(filepath string) ([]dns.RR, error) {
file, err := os.Open(filepath)
if err != nil {
return nil, err
}
parser := dns.NewZoneParser(file, "", "")
var rrs = make([]dns.RR, 0)
for rr, ok := parser.Next(); ok; rr, ok = parser.Next() {
rrs = append(rrs, rr)
}
if err := parser.Err(); err != nil {
log.Println(err)
}
return rrs, nil
}
func createServer(zones []zone, config config) *dns.ServeMux {
srv := dns.NewServeMux()
for _, z := range zones {
srv.HandleFunc(z.zone, func(w dns.ResponseWriter, r *dns.Msg) {
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative = true
// maybe only support one question per query like most servers do it ???
for _, q := range r.Question {
rr := z.rr[q.Qtype]
m.Answer = append(m.Answer, rr[q.Name]...)
// Handle extras
switch q.Qtype {
case dns.TypeMX:
// Resolve MX domains
for _, mxRR := range rr[q.Name] {
if t, ok := mxRR.(*dns.MX); ok {
m.Extra = append(m.Extra, z.rr[dns.TypeA][t.Mx]...)
m.Extra = append(m.Extra, z.rr[dns.TypeAAAA][t.Mx]...)
}
}
case dns.TypeA, dns.TypeAAAA:
if len(m.Answer) == 0 {
// no A or AAAA found. Look for CNAME
m.Answer = append(m.Answer, z.rr[dns.TypeCNAME][q.Name]...)
if len(m.Answer) != 0 {
// Resolve CNAME
for _, nameRR := range m.Answer {
if t, ok := nameRR.(*dns.CNAME); ok {
m.Answer = append(m.Answer, z.rr[q.Qtype][t.Target]...)
}
}
}
}
case dns.TypeNS:
// Resove NS records
for _, nsRR := range rr[q.Name] {
if t, ok := nsRR.(*dns.NS); ok {
m.Extra = append(m.Extra, z.rr[dns.TypeA][t.Ns]...)
m.Extra = append(m.Extra, z.rr[dns.TypeAAAA][t.Ns]...)
}
}
}
}
w.WriteMsg(m)
})
}
return srv
}
func listenAndServer(server *dns.ServeMux) {
go func() {
if err := dns.ListenAndServe(":"+strconv.Itoa(8053), "udp", server); err != nil {
log.Fatalf("Failed to set udp listener %s\n", err.Error())
}
}()
go func() {
if err := dns.ListenAndServe(":"+strconv.Itoa(8053), "tcp", server); err != nil {
log.Fatalf("Failed to set tcp listener %s\n", err.Error())
}
}()
sig := make(chan os.Signal)
signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
s := <-sig
log.Printf("Signal (%v) received, stopping\n", s)
os.Exit(0)
}
func main() {
config, err := loadConfig()
if err != nil {
log.Fatalf("Failed to load config: %s", err.Error())
}
zones, err := loadZones(config.Zones)
if err != nil {
log.Fatalf("Failed to load zones: %s", err.Error())
}
server := createServer(zones, *config)
listenAndServer(server)
}

8
go.mod Normal file
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module git.kapelle.org/niklas/cool-dns
go 1.15
require (
github.com/miekg/dns v1.1.35
gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776
)

23
go.sum Normal file
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github.com/miekg/dns v1.1.35 h1:oTfOaDH+mZkdcgdIjH6yBajRGtIwcwcaR+rt23ZSrJs=
github.com/miekg/dns v1.1.35/go.mod h1:KNUDUusw/aVsxyTYZM1oqvCicbwhgbNgztCETuNZ7xM=
golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550 h1:ObdrDkeb4kJdCP557AjRjq69pTHfNouLtWZG7j9rPN8=
golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
golang.org/x/net v0.0.0-20190923162816-aa69164e4478 h1:l5EDrHhldLYb3ZRHDUhXF7Om7MvYXnkV9/iQNo1lX6g=
golang.org/x/net v0.0.0-20190923162816-aa69164e4478/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
golang.org/x/sync v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEhagSSnXWGV915qUMm9mrU=
golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/sys v0.0.0-20190924154521-2837fb4f24fe h1:6fAMxZRR6sl1Uq8U61gxU+kPTs2tR8uOySCbBP7BN/M=
golang.org/x/sys v0.0.0-20190924154521-2837fb4f24fe/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
golang.org/x/tools v0.0.0-20191216052735-49a3e744a425/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776 h1:tQIYjPdBoyREyB9XMu+nnTclpTYkz2zFM+lzLJFO4gQ=
gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

18
zonefile.txt Normal file
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$ORIGIN example.com. ; designates the start of this zone file in the namespace
$TTL 3600 ; default expiration time (in seconds) of all RRs without their own TTL value
example.com. IN SOA ns.example.com. username.example.com. ( 2020091025 7200 3600 1209600 3600 )
example.com. IN NS ns ; ns.example.com is a nameserver for example.com
example.com. IN NS ns.somewhere.example. ; ns.somewhere.example is a backup nameserver for example.com
example.com. IN MX 10 mail.example.com. ; mail.example.com is the mailserver for example.com
@ IN MX 20 mail2.example.com. ; equivalent to above line, "@" represents zone origin
@ IN MX 50 mail3 ; equivalent to above line, but using a relative host name
example.com. IN A 192.0.2.1 ; IPv4 address for example.com
example.com. IN A 192.0.3.1 ; IPv4 address for example.com
IN AAAA 2001:db8:10::1 ; IPv6 address for example.com
ns IN A 192.0.2.2 ; IPv4 address for ns.example.com
IN AAAA 2001:db8:10::2 ; IPv6 address for ns.example.com
www IN CNAME example.com. ; www.example.com is an alias for example.com
wwwtest IN CNAME www ; wwwtest.example.com is another alias for www.example.com
mail IN A 192.0.2.3 ; IPv4 address for mail.example.com
mail2 IN A 192.0.2.4 ; IPv4 address for mail2.example.com
mail3 IN A 192.0.2.5 ; IPv4 address for mail3.example.com