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Diffstat (limited to 'plugin/erratic/erratic.go')
-rw-r--r--plugin/erratic/erratic.go95
1 files changed, 95 insertions, 0 deletions
diff --git a/plugin/erratic/erratic.go b/plugin/erratic/erratic.go
new file mode 100644
index 000000000..5b8cd30c9
--- /dev/null
+++ b/plugin/erratic/erratic.go
@@ -0,0 +1,95 @@
+// Package erratic implements a plugin that returns erratic answers (delayed, dropped).
+package erratic
+
+import (
+ "sync/atomic"
+ "time"
+
+ "github.com/coredns/coredns/request"
+
+ "github.com/miekg/dns"
+ "golang.org/x/net/context"
+)
+
+// Erratic is a plugin that returns erratic repsonses to each client.
+type Erratic struct {
+ drop uint64
+
+ delay uint64
+ duration time.Duration
+
+ truncate uint64
+
+ q uint64 // counter of queries
+}
+
+// ServeDNS implements the plugin.Handler interface.
+func (e *Erratic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+ state := request.Request{W: w, Req: r}
+ drop := false
+ delay := false
+ trunc := false
+
+ queryNr := atomic.LoadUint64(&e.q)
+ atomic.AddUint64(&e.q, 1)
+
+ if e.drop > 0 && queryNr%e.drop == 0 {
+ drop = true
+ }
+ if e.delay > 0 && queryNr%e.delay == 0 {
+ delay = true
+ }
+ if e.truncate > 0 && queryNr&e.truncate == 0 {
+ trunc = true
+ }
+
+ m := new(dns.Msg)
+ m.SetReply(r)
+ m.Compress = true
+ m.Authoritative = true
+ if trunc {
+ m.Truncated = true
+ }
+
+ // small dance to copy rrA or rrAAAA into a non-pointer var that allows us to overwrite the ownername
+ // in a non-racy way.
+ switch state.QType() {
+ case dns.TypeA:
+ rr := *(rrA.(*dns.A))
+ rr.Header().Name = state.QName()
+ m.Answer = append(m.Answer, &rr)
+ case dns.TypeAAAA:
+ rr := *(rrAAAA.(*dns.AAAA))
+ rr.Header().Name = state.QName()
+ m.Answer = append(m.Answer, &rr)
+ default:
+ if !drop {
+ if delay {
+ time.Sleep(e.duration)
+ }
+ // coredns will return error.
+ return dns.RcodeServerFailure, nil
+ }
+ }
+
+ if drop {
+ return 0, nil
+ }
+
+ if delay {
+ time.Sleep(e.duration)
+ }
+
+ state.SizeAndDo(m)
+ w.WriteMsg(m)
+
+ return 0, nil
+}
+
+// Name implements the Handler interface.
+func (e *Erratic) Name() string { return "erratic" }
+
+var (
+ rrA, _ = dns.NewRR(". IN 0 A 192.0.2.53")
+ rrAAAA, _ = dns.NewRR(". IN 0 AAAA 2001:DB8::53")
+)