Mirrors/coredns
1
0
Fork 0
mirror of https://github.com/coredns/coredns.git synced 2025-11-27 22:24:09 -05:00
Code Issues Packages Projects Releases Wiki Activity

Add test for CNAME ordering

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

23
middleware/loadbalance/loadbalance.go
View File

@@ -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.

4
middleware/loadbalance/loadbalance.md
View File

@@ -4,13 +4,15 @@
message. See [Wikipedia](https://en.wikipedia.org/wiki/Round-robin_DNS) about the pros and cons
on this setup.
It will take care to sort any CNAMEs before any address records.
## Syntax
~~~
loadbalance [policy]
~~~
* policy is how to balance, the default is "round_robin"
* `policy` is how to balance, the default is "round_robin"
## Examples

104
middleware/loadbalance/loadbalance_test.go Normal file
View File

@@ -0,0 +1,104 @@
package loadbalance
import (
"testing"
"github.com/miekg/coredns/middleware"
"github.com/miekg/dns"
"golang.org/x/net/context"
)
func TestLoadBalance(t *testing.T) {
rm := RoundRobin{Next: handler()}
// the first X records must be cnames after this test
tests := []struct {
answer []dns.RR
extra []dns.RR
cnameAnswer int
cnameExtra int
}{
{
answer: []dns.RR{
newCNAME("cname1.region2.skydns.test. 300 IN CNAME cname2.region2.skydns.test."),
newCNAME("cname2.region2.skydns.test. 300 IN CNAME cname3.region2.skydns.test."),
newCNAME("cname5.region2.skydns.test. 300 IN CNAME cname6.region2.skydns.test."),
newCNAME("cname6.region2.skydns.test. 300 IN CNAME endpoint.region2.skydns.test."),
newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.1"),
},
cnameAnswer: 4,
},
{
answer: []dns.RR{
newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.1"),
newCNAME("cname.region2.skydns.test. 300 IN CNAME endpoint.region2.skydns.test."),
},
cnameAnswer: 1,
},
{
answer: []dns.RR{
newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.1"),
newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.2"),
newCNAME("cname2.region2.skydns.test. 300 IN CNAME cname3.region2.skydns.test."),
newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.3"),
},
extra: []dns.RR{
newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.1"),
newAAAA("endpoint.region2.skydns.test. 300 IN AAAA ::1"),
newCNAME("cname2.region2.skydns.test. 300 IN CNAME cname3.region2.skydns.test."),
newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.3"),
newAAAA("endpoint.region2.skydns.test. 300 IN AAAA ::2"),
},
cnameAnswer: 1,
cnameExtra: 1,
},
}
rec := middleware.NewResponseRecorder(&middleware.TestResponseWriter{})
for i, test := range tests {
req := new(dns.Msg)
req.SetQuestion("region2.skydns.test.", dns.TypeSRV)
req.Answer = test.answer
req.Extra = test.extra
_, err := rm.ServeDNS(context.TODO(), rec, req)
if err != nil {
t.Errorf("Test %d: Expected no error, but got %s", i, err)
continue
}
cname := 0
for _, r := range rec.Msg().Answer {
if r.Header().Rrtype != dns.TypeCNAME {
break
}
cname++
}
if cname != test.cnameAnswer {
t.Errorf("Test %d: Expected %d cnames in Answer, but got %d", i, test.cnameAnswer, cname)
}
cname = 0
for _, r := range rec.Msg().Extra {
if r.Header().Rrtype != dns.TypeCNAME {
break
}
cname++
}
if cname != test.cnameExtra {
t.Errorf("Test %d: Expected %d cname in Extra, but got %d", i, test.cnameExtra, cname)
}
}
}
func handler() middleware.Handler {
return middleware.HandlerFunc(func(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
w.WriteMsg(r)
return dns.RcodeSuccess, nil
})
}
func newA(rr string) *dns.A { r, _ := dns.NewRR(rr); return r.(*dns.A) }
func newAAAA(rr string) *dns.AAAA { r, _ := dns.NewRR(rr); return r.(*dns.AAAA) }
func newCNAME(rr string) *dns.CNAME { r, _ := dns.NewRR(rr); return r.(*dns.CNAME) }