diff options
Diffstat (limited to 'plugin/erratic/erratic.go')
-rw-r--r-- | plugin/erratic/erratic.go | 95 |
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") +) |