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Kubernetes srv (#823)

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* Treat absence of port/service in SRV as wildcard

Normally, a SRV-request should have the form
_<service>._<port>.<name>.<zone>. The k8s peer-finder which is used for
bootstrapping by some applications will however query for SRV at
<name>.<zone>.

To compensate for this behaviour, treat the absence of _<service> and
_<port> as wildcards.

* Modified tests with new SRV behaviour

Added a testcase for a SRV request without port & service
Removed now valid query from invalidSRVQueries

* Forgot to run gofmt on test/kubernetes_test.go
This commit is contained in:
Markus Sommer 2017-08-04 15:41:55 +02:00 • committed by John Belamaric
parent 2c0fc3182c
commit d0d7f4c89a
3 changed files with 35 additions and 25 deletions
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52
middleware/kubernetes/kubernetes.go
View file

@ -299,34 +299,42 @@ func (k *Kubernetes) parseRequest(lowerCasedName string, qtype uint16) (r record
offset := 0
if qtype == dns.TypeSRV {
if len(segs) != 5 {
return r, errInvalidRequest
}
// This is a SRV style request, get first two elements as port and
// protocol, stripping leading underscores if present.
if segs[0][0] == '_' {
r.port = segs[0][1:]
// The kubernetes peer-finder expects queries with empty port and service to resolve
// If neither is specified, treat it as a wildcard
if len(segs) == 3 {
r.port = "*"
r.service = "*"
offset = 0
} else {
r.port = segs[0]
if !symbolContainsWildcard(r.port) {
if len(segs) != 5 {
return r, errInvalidRequest
}
}
if segs[1][0] == '_' {
r.protocol = segs[1][1:]
if r.protocol != "tcp" && r.protocol != "udp" {
return r, errInvalidRequest
}
} else {
r.protocol = segs[1]
if !symbolContainsWildcard(r.protocol) {
// This is a SRV style request, get first two elements as port and
// protocol, stripping leading underscores if present.
if segs[0][0] == '_' {
r.port = segs[0][1:]
} else {
r.port = segs[0]
if !symbolContainsWildcard(r.port) {
return r, errInvalidRequest
}
}
if segs[1][0] == '_' {
r.protocol = segs[1][1:]
if r.protocol != "tcp" && r.protocol != "udp" {
return r, errInvalidRequest
}
} else {
r.protocol = segs[1]
if !symbolContainsWildcard(r.protocol) {
return r, errInvalidRequest
}
}
if r.port == "" || r.protocol == "" {
return r, errInvalidRequest
}
offset = 2
}
if r.port == "" || r.protocol == "" {
return r, errInvalidRequest
}
offset = 2
}
if (qtype == dns.TypeA || qtype == dns.TypeAAAA) && len(segs) == 4 {
// This is an endpoint A/AAAA record request. Get first element as endpoint.

1
middleware/kubernetes/kubernetes_test.go
View file

@ -227,7 +227,6 @@ func TestParseRequest(t *testing.T) {
}
invalidSRVQueries := []string{
"webs.mynamespace.svc.inter.webs.test.", // SRV requests must have port and protocol
"_http._pcp.webs.mynamespace.svc.inter.webs.test.", // SRV protocol must be tcp or udp
"_http._tcp.ep.webs.ns.svc.inter.webs.test.", // SRV requests cannot have an endpoint
"_*._*.webs.mynamespace.svc.inter.webs.test.", // SRV request with invalid wildcards

7
test/kubernetes_test.go
View file

@ -207,8 +207,11 @@ var dnsTestCases = []test.Case{
},
{
Qname: "svc-1-a.test-1.svc.cluster.local.", Qtype: dns.TypeSRV,
Rcode: dns.RcodeNameError,
Answer: []dns.RR{},
Rcode: dns.RcodeSuccess,
Answer: []dns.RR{
test.SRV("_http._tcp.svc-1-a.test-1.svc.cluster.local. 303 IN SRV 10 100 80 svc-1-a.test-1.svc.cluster.local."),
test.SRV("_https._tcp.svc-1-a.test-1.svc.cluster.local. 303 IN SRV 10 100 443 svc-1-a.test-1.svc.cluster.local."),
},
},
{
Qname: "10-20-0-101.test-1.pod.cluster.local.", Qtype: dns.TypeA,