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8f9f2cd1ab
This middleware acts in the same way as SkyDNS. We might add options
to allow it to be behave different, but for now it will suffice.
A Corefile like:
.:1053 {
etcd miek.nl
proxy . 8.8.8.8:53
}
will perform lookup in etcd and proxy everything not miek.nl to Google
for further resolution.
The internal etcd forwarding *also* uses the proxy infrastructure,
meaning you get health check and such for (almost) free
75 lines
1.7 KiB
Go
75 lines
1.7 KiB
Go
package etcd
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import (
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"github.com/miekg/coredns/middleware"
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"github.com/miekg/dns"
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"golang.org/x/net/context"
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)
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func (e Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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state := middleware.State{W: w, Req: r}
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zone := middleware.Zones(e.Zones).Matches(state.Name())
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if zone == "" {
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return e.Next.ServeDNS(ctx, w, r)
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}
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m := state.AnswerMessage()
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m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
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var (
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records, extra []dns.RR
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err error
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)
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switch state.Type() {
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case "A":
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records, err = e.A(zone, state, nil)
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case "AAAA":
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records, err = e.AAAA(zone, state, nil)
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case "TXT":
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records, err = e.TXT(zone, state)
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case "CNAME":
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records, err = e.CNAME(zone, state)
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case "MX":
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records, extra, err = e.MX(zone, state)
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case "SRV":
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records, extra, err = e.SRV(zone, state)
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default:
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// For SOA and NS we might still want this
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// and use dns.<zones> as the name to put these
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// also for stub
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// rwrite and return
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// Nodata response
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// also catch other types, so that they return NODATA
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return 0, nil
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}
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if isEtcdNameError(err) {
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NameError(zone, state)
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return dns.RcodeNameError, nil
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}
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if err != nil {
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return dns.RcodeServerFailure, err
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}
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if len(records) > 0 {
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m.Answer = append(m.Answer, records...)
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}
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if len(extra) > 0 {
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m.Extra = append(m.Extra, extra...)
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}
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state.W.WriteMsg(m)
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return 0, nil
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}
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// NameError writes a name error to the client.
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func NameError(zone string, state middleware.State) {
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m := new(dns.Msg)
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m.SetRcode(state.Req, dns.RcodeNameError)
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m.Ns = []dns.RR{SOA(zone)}
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state.W.WriteMsg(m)
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}
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// NoData write a nodata response to the client.
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func NoData(zone string, state middleware.State) {
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// TODO(miek): write it
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}
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