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plugin/kubernetes: error NXDOMAIN for TXT lookups (#5737)

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plugin/kubernetes: fix NXDOMAIN/NOERROR responses for TXT queries

Signed-off-by: Laurence Robinson <laurence_robinson@live.co.uk>
Co-authored-by: Laurence Robinson <laurence.robinson@deshaw.com>
This commit is contained in:
LAMRobinson 2022-12-13 20:36:46 +00:00 • committed by GitHub
parent 7813b6e090
commit c3228615e0
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2 changed files with 30 additions and 6 deletions
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16
plugin/kubernetes/handler_test.go
View file

@ -247,6 +247,22 @@ var dnsTestCases = []kubeTestCase{
test.TXT("dns-version.cluster.local 28800 IN TXT 1.1.0"),
},
}},
// A TXT record does not exist but another record for the same FQDN does
{Case: test.Case{
Qname: "svc1.testns.svc.cluster.local.", Qtype: dns.TypeTXT,
Rcode: dns.RcodeSuccess,
Ns: []dns.RR{
test.SOA("cluster.local. 5 IN SOA ns.dns.cluster.local. hostmaster.cluster.local. 1499347823 7200 1800 86400 5"),
},
}},
// A TXT record does not exist and neither does another record for the same FQDN
{Case: test.Case{
Qname: "svc0.svc-nons.svc.cluster.local.", Qtype: dns.TypeTXT,
Rcode: dns.RcodeNameError,
Ns: []dns.RR{
test.SOA("cluster.local. 5 IN SOA ns.dns.cluster.local. hostmaster.cluster.local. 1499347823 7200 1800 86400 5"),
},
}},
// A Service (Headless) does not exist
{Case: test.Case{
Qname: "bogusendpoint.hdls1.testns.svc.cluster.local.", Qtype: dns.TypeA,

20
plugin/kubernetes/kubernetes.go
View file

@ -100,15 +100,23 @@ func (k *Kubernetes) Services(ctx context.Context, state request.Request, exact
// 1 label + zone, label must be "dns-version".
t, _ := dnsutil.TrimZone(state.Name(), state.Zone)
// Hard code the only valid TXT - "dns-version.<zone>"
segs := dns.SplitDomainName(t)
if len(segs) != 1 {
if len(segs) == 1 && segs[0] == "dns-version" {
svc := msg.Service{Text: DNSSchemaVersion, TTL: 28800, Key: msg.Path(state.QName(), coredns)}
return []msg.Service{svc}, nil
}
// Check if we have an existing record for this query of another type
services, _ := k.Records(ctx, state, false)
if len(services) > 0 {
// If so we return an empty NOERROR
return nil, nil
}
if segs[0] != "dns-version" {
return nil, nil
}
svc := msg.Service{Text: DNSSchemaVersion, TTL: 28800, Key: msg.Path(state.QName(), coredns)}
return []msg.Service{svc}, nil
// Return NXDOMAIN for no match
return nil, errNoItems
case dns.TypeNS:
// We can only get here if the qname equals the zone, see ServeDNS in handler.go.