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Add test for CNAME ordering

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Add a test for SkyDNS':
https://github.com/skynetservices/skydns/issues/217

Put the CNAME in front for both answer and extra sections. Note that
the etcd middleware seems to already to the correct thing though.
This commit is contained in:
Miek Gieben
2016-03-26 09:53:40 +00:00
parent 8cf1c89743
commit b2c221c9cd
4 changed files with 216 additions and 11 deletions
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23
middleware/loadbalance/loadbalance.go
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@@ -14,18 +14,21 @@ func (r *RoundRobinResponseWriter) WriteMsg(res *dns.Msg) error {
if res.Rcode != dns.RcodeSuccess {
return r.ResponseWriter.WriteMsg(res)
}
if len(res.Answer) < 2 { // don't even bother
return r.ResponseWriter.WriteMsg(res)
}
// put CNAMEs first, randomize a/aaaa's and put packet back together.
// TODO(miek): check family and give v6 more prio?
res.Answer = roundRobin(res.Answer)
res.Extra = roundRobin(res.Extra)
return r.ResponseWriter.WriteMsg(res)
}
func roundRobin(in []dns.RR) []dns.RR {
cname := []dns.RR{}
address := []dns.RR{}
rest := []dns.RR{}
for _, r := range res.Answer {
for _, r := range in {
switch r.Header().Rrtype {
case dns.TypeCNAME:
// d d d d DNAME and friends here as well?
cname = append(cname, r)
case dns.TypeA, dns.TypeAAAA:
address = append(address, r)
@@ -36,7 +39,7 @@ func (r *RoundRobinResponseWriter) WriteMsg(res *dns.Msg) error {
switch l := len(address); l {
case 0, 1:
return r.ResponseWriter.WriteMsg(res)
break
case 2:
if dns.Id()%2 == 0 {
address[0], address[1] = address[1], address[0]
@@ -51,9 +54,9 @@ func (r *RoundRobinResponseWriter) WriteMsg(res *dns.Msg) error {
address[q], address[p] = address[p], address[q]
}
}
res.Answer = append(cname, rest...)
res.Answer = append(res.Answer, address...)
return r.ResponseWriter.WriteMsg(res)
out := append(cname, rest...)
out = append(out, address...)
return out
}
// Should we pack and unpack here to fiddle with the packet... Not likely.