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// Package chaos implements a plugin that answer to 'CH version.bind TXT' type queries.
package chaos
import (
"context"
"math/rand"
"os"
"time"
"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
)
// Chaos allows CoreDNS to reply to CH TXT queries and return author or
// version information.
type Chaos struct {
Next plugin.Handler
Version string
Authors []string
}
// ServeDNS implements the plugin.Handler interface.
func (c Chaos) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := request.Request{W: w, Req: r}
if state.QClass() != dns.ClassCHAOS || state.QType() != dns.TypeTXT {
return plugin.NextOrFailure(c.Name(), c.Next, ctx, w, r)
}
m := new(dns.Msg)
m.SetReply(r)
hdr := dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeTXT, Class: dns.ClassCHAOS, Ttl: 0}
switch state.Name() {
default:
return plugin.NextOrFailure(c.Name(), c.Next, ctx, w, r)
case "authors.bind.":
rnd := rand.New(rand.NewSource(time.Now().Unix()))
for _, i := range rnd.Perm(len(c.Authors)) {
m.Answer = append(m.Answer, &dns.TXT{Hdr: hdr, Txt: []string{c.Authors[i]}})
}
case "version.bind.", "version.server.":
m.Answer = []dns.RR{&dns.TXT{Hdr: hdr, Txt: []string{c.Version}}}
case "hostname.bind.", "id.server.":
hostname, err := os.Hostname()
if err != nil {
hostname = "localhost"
}
m.Answer = []dns.RR{&dns.TXT{Hdr: hdr, Txt: []string{trim(hostname)}}}
}
w.WriteMsg(m)
return 0, nil
}
// Name implements the Handler interface.
func (c Chaos) Name() string { return "chaos" }
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