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package kubernetes
import (
"fmt"
"log"
"strings"
"github.com/miekg/coredns/middleware"
"github.com/miekg/dns"
"golang.org/x/net/context"
)
func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
log.Printf("[debug] here entering ServeDNS: ctx:%v dnsmsg:%v\n", ctx, r)
state := middleware.State{W: w, Req: r}
if state.QClass() != dns.ClassINET {
return dns.RcodeServerFailure, fmt.Errorf("can only deal with ClassINET")
}
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
// TODO: find an alternative to this block
if strings.HasSuffix(state.Name(), arpaSuffix) {
ip, _ := extractIP(state.Name())
records := k.getServiceRecordForIP(ip, state.Name())
if len(records) > 0 {
srvPTR := &records[0]
m.Answer = append(m.Answer, srvPTR.NewPTR(state.QName(), ip))
m = dedup(m)
state.SizeAndDo(m)
m, _ = state.Scrub(m)
w.WriteMsg(m)
return dns.RcodeSuccess, nil
}
}
// Check that query matches one of the zones served by this middleware,
// otherwise delegate to the next in the pipeline.
zone := middleware.Zones(k.Zones).Matches(state.Name())
if zone == "" {
if k.Next == nil {
return dns.RcodeServerFailure, nil
}
return k.Next.ServeDNS(ctx, w, r)
}
var (
records, extra []dns.RR
err error
)
switch state.Type() {
case "A":
records, err = k.A(zone, state, nil)
case "AAAA":
records, err = k.AAAA(zone, state, nil)
case "TXT":
records, err = k.TXT(zone, state)
// TODO: change lookup to return appropriate error. Then add code below
// this switch to check for the error and return not implemented.
//return dns.RcodeNotImplemented, nil
case "CNAME":
records, err = k.CNAME(zone, state)
case "MX":
records, extra, err = k.MX(zone, state)
case "SRV":
records, extra, err = k.SRV(zone, state)
case "SOA":
records = []dns.RR{k.SOA(zone, state)}
case "NS":
if state.Name() == zone {
records, extra, err = k.NS(zone, state)
break
}
fallthrough
default:
// Do a fake A lookup, so we can distinguish betwen NODATA and NXDOMAIN
_, err = k.A(zone, state, nil)
}
if isKubernetesNameError(err) {
return k.Err(zone, dns.RcodeNameError, state)
}
if err != nil {
return dns.RcodeServerFailure, err
}
if len(records) == 0 {
return k.Err(zone, dns.RcodeSuccess, state)
}
m.Answer = append(m.Answer, records...)
m.Extra = append(m.Extra, extra...)
m = dedup(m)
state.SizeAndDo(m)
m, _ = state.Scrub(m)
w.WriteMsg(m)
return dns.RcodeSuccess, nil
}
// NoData write a nodata response to the client.
func (k Kubernetes) Err(zone string, rcode int, state middleware.State) (int, error) {
m := new(dns.Msg)
m.SetRcode(state.Req, rcode)
m.Ns = []dns.RR{k.SOA(zone, state)}
state.SizeAndDo(m)
state.W.WriteMsg(m)
return rcode, nil
}
func dedup(m *dns.Msg) *dns.Msg {
// TODO(miek): expensive!
m.Answer = dns.Dedup(m.Answer, nil)
m.Ns = dns.Dedup(m.Ns, nil)
m.Extra = dns.Dedup(m.Extra, nil)
return m
}
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