e082bb5a61
* plugin/trace: fix struct allignment A 64 bit entity needs to be the first in a struct to make it work on 32 bit systems. Fixes: #4111 Signed-off-by: Miek Gieben <miek@miek.nl> * plugin/erratic does makes the same mistake Signed-off-by: Miek Gieben <miek@miek.nl>
109 lines
2.1 KiB
Go
109 lines
2.1 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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q uint64 // counter of queries
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drop uint64
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delay uint64
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truncate uint64
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duration time.Duration
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large bool // undocumented feature; return large responses for A request (>512B, to test compression).
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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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if e.large {
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for i := 0; i < 29; i++ {
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m.Answer = append(m.Answer, &rr)
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}
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}
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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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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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