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package external
import (
"context"
"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/plugin/etcd/msg"
"github.com/coredns/coredns/plugin/transfer"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
)
// Transfer implements transfer.Transferer
func (e *External) Transfer(zone string, serial uint32) (<-chan []dns.RR, error) {
z := plugin.Zones(e.Zones).Matches(zone)
if z != zone {
return nil, transfer.ErrNotAuthoritative
}
ctx := context.Background()
ch := make(chan []dns.RR, 2)
if zone == "." {
zone = ""
}
state := request.Request{Zone: zone}
// SOA
soa := e.soa(state)
ch <- []dns.RR{soa}
if serial != 0 && serial >= soa.Serial {
close(ch)
return ch, nil
}
go func() {
// Add NS
nsName := "ns1." + e.apex + "." + zone
nsHdr := dns.RR_Header{Name: zone, Rrtype: dns.TypeNS, Ttl: e.ttl, Class: dns.ClassINET}
ch <- []dns.RR{&dns.NS{Hdr: nsHdr, Ns: nsName}}
// Add Nameserver A/AAAA records
nsRecords := e.externalAddrFunc(state)
for i := range nsRecords {
// externalAddrFunc returns incomplete header names, correct here
nsRecords[i].Header().Name = nsName
nsRecords[i].Header().Ttl = e.ttl
ch <- []dns.RR{nsRecords[i]}
}
svcs := e.externalServicesFunc(zone)
srvSeen := make(map[string]struct{})
for i := range svcs {
name := msg.Domain(svcs[i].Key)
if svcs[i].TargetStrip == 0 {
// Add Service A/AAAA records
s := request.Request{Req: &dns.Msg{Question: []dns.Question{{Name: name}}}}
as, _ := e.a(ctx, []msg.Service{svcs[i]}, s)
if len(as) > 0 {
ch <- as
}
aaaas, _ := e.aaaa(ctx, []msg.Service{svcs[i]}, s)
if len(aaaas) > 0 {
ch <- aaaas
}
// Add bare SRV record, ensuring uniqueness
recs, _ := e.srv(ctx, []msg.Service{svcs[i]}, s)
for _, srv := range recs {
if !nameSeen(srvSeen, srv) {
ch <- []dns.RR{srv}
}
}
continue
}
// Add full SRV record, ensuring uniqueness
s := request.Request{Req: &dns.Msg{Question: []dns.Question{{Name: name}}}}
recs, _ := e.srv(ctx, []msg.Service{svcs[i]}, s)
for _, srv := range recs {
if !nameSeen(srvSeen, srv) {
ch <- []dns.RR{srv}
}
}
}
ch <- []dns.RR{soa}
close(ch)
}()
return ch, nil
}
func nameSeen(namesSeen map[string]struct{}, rr dns.RR) bool {
if _, duplicate := namesSeen[rr.Header().Name]; duplicate {
return true
}
namesSeen[rr.Header().Name] = struct{}{}
return false
}
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