d998aa6c25
* plugin/erratic: add axfr support Add support for axfr. This to fix and test long standing axfr issues that are hard to test if we don't support it directly in coredns. The most intriguing feature is withholding the last SOA from a response so the client needs to wait; drop (no reply) and delay is also supported. All TTLs are set to zero. Add simple tests that checks if first record is a SOA. Signed-off-by: Miek Gieben <miek@miek.nl> * more test coverage Signed-off-by: Miek Gieben <miek@miek.nl>
106 lines
2 KiB
Go
106 lines
2 KiB
Go
// Package erratic implements a plugin that returns erratic answers (delayed, dropped).
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package erratic
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import (
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"context"
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"sync/atomic"
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"time"
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"github.com/coredns/coredns/request"
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"github.com/miekg/dns"
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)
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// Erratic is a plugin that returns erratic responses to each client.
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type Erratic struct {
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drop uint64
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delay uint64
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duration time.Duration
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truncate uint64
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q uint64 // counter of queries
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}
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// ServeDNS implements the plugin.Handler interface.
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func (e *Erratic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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state := request.Request{W: w, Req: r}
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drop := false
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delay := false
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trunc := false
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queryNr := atomic.LoadUint64(&e.q)
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atomic.AddUint64(&e.q, 1)
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if e.drop > 0 && queryNr%e.drop == 0 {
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drop = true
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}
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if e.delay > 0 && queryNr%e.delay == 0 {
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delay = true
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}
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if e.truncate > 0 && queryNr&e.truncate == 0 {
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trunc = true
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}
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m := new(dns.Msg)
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m.SetReply(r)
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m.Authoritative = true
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if trunc {
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m.Truncated = true
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}
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// small dance to copy rrA or rrAAAA into a non-pointer var that allows us to overwrite the ownername
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// in a non-racy way.
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switch state.QType() {
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case dns.TypeA:
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rr := *(rrA.(*dns.A))
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rr.Header().Name = state.QName()
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m.Answer = append(m.Answer, &rr)
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case dns.TypeAAAA:
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rr := *(rrAAAA.(*dns.AAAA))
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rr.Header().Name = state.QName()
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m.Answer = append(m.Answer, &rr)
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case dns.TypeAXFR:
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if drop {
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return 0, nil
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}
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if delay {
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time.Sleep(e.duration)
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}
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xfr(state, trunc)
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return 0, nil
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default:
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if drop {
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return 0, nil
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}
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if delay {
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time.Sleep(e.duration)
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}
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// coredns will return error.
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return dns.RcodeServerFailure, nil
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}
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if drop {
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return 0, nil
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}
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if delay {
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time.Sleep(e.duration)
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}
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state.SizeAndDo(m)
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w.WriteMsg(m)
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return 0, nil
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}
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// Name implements the Handler interface.
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func (e *Erratic) Name() string { return "erratic" }
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var (
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rrA, _ = dns.NewRR(". IN 0 A 192.0.2.53")
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rrAAAA, _ = dns.NewRR(". IN 0 AAAA 2001:DB8::53")
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)
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