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stub.go
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stub.go
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package etcd
import (
"log"
"net"
"strconv"
"strings"
"time"
"github.com/miekg/coredns/middleware/etcd/msg"
"github.com/miekg/coredns/middleware/proxy"
"github.com/miekg/dns"
)
func (e Etcd) UpdateStubZones() {
go func() {
for {
e.updateStubZones()
time.Sleep(15 * time.Second)
}
}()
}
// Look in .../dns/stub/<zone>/xx for msg.Services. Loop through them
// extract <zone> and add them as forwarders (ip:port-combos) for
// the stub zones. Only numeric (i.e. IP address) hosts are used.
// Only the first zone configured on e is used for the lookup.
func (e *Etcd) updateStubZones() {
zone := e.Zones[0]
services, err := e.Records(stubDomain+"."+zone, false)
if err != nil {
return
}
stubmap := make(map[string]proxy.Proxy)
// track the nameservers on a per domain basis, but allow a list on the domain.
nameservers := map[string][]string{}
for _, serv := range services {
if serv.Port == 0 {
serv.Port = 53
}
ip := net.ParseIP(serv.Host)
if ip == nil {
log.Printf("[WARNING] Non IP address stub nameserver: %s", serv.Host)
continue
}
domain := msg.Domain(serv.Key)
labels := dns.SplitDomainName(domain)
// If the remaining name equals any of the zones we have, we ignore it.
for _, z := range e.Zones {
// Chop of left most label, because that is used as the nameserver place holder
// and drop the right most labels that belong to zone.
// We must *also* chop of dns.stub. which means cutting two more labels.
domain = dns.Fqdn(strings.Join(labels[1:len(labels)-dns.CountLabel(z)-2], "."))
if domain == z {
log.Printf("[WARNING] Skipping nameserver for domain we are authoritative for: %s", domain)
continue
}
nameservers[domain] = append(nameservers[domain], net.JoinHostPort(serv.Host, strconv.Itoa(serv.Port)))
}
}
for domain, nss := range nameservers {
stubmap[domain] = proxy.New(nss)
}
// atomic swap (at least that's what we hope it is)
if len(stubmap) > 0 {
e.Stubmap = &stubmap
}
return
}