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handler.go
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/
handler.go
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package redis
import (
"context"
"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
)
// ServeDNS implements the plugin.Handler interface.
func (redis Redis) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := request.Request{W: w, Req: r}
zone := plugin.Zones(redis.Zones).Matches(state.Name())
if zone == "" {
return plugin.NextOrFailure(redis.Name(), redis.Next, ctx, w, r)
}
var (
records, extra []dns.RR
truncated bool
err error
)
switch state.QType() {
case dns.TypeA:
records, truncated, err = redis.A(ctx, zone, state, nil)
case dns.TypeAAAA:
records, truncated, err = redis.AAAA(ctx, zone, state, nil)
case dns.TypeCNAME:
records, err = redis.CNAME(ctx, zone, state)
case dns.TypeTXT:
records, truncated, err = redis.TXT(ctx, zone, state, nil)
case dns.TypeNS:
records, truncated, err = redis.NS(ctx, zone, state, nil)
case dns.TypeMX:
records, truncated, err = redis.MX(ctx, zone, state, nil)
case dns.TypeSRV:
records, truncated, err = redis.SRV(ctx, zone, state, nil)
case dns.TypePTR:
records, err = redis.PTR(ctx, zone, state)
case dns.TypeSOA:
records, err = redis.SOA(ctx, zone, state)
case dns.TypeCAA:
records, err = redis.CAA(ctx, zone, state)
default:
return redis.errorANSWER(ctx, state.QName(), dns.RcodeNotImplemented, state, nil)
}
if err != nil {
if err == errKeyNotFound && redis.Fall.Through(state.Name()) {
return plugin.NextOrFailure(redis.Name(), redis.Next, ctx, w, r)
}
// Make err nil when returning here, so we don't log spam for NXDOMAIN.
return redis.errorANSWER(ctx, state.QName(), dns.RcodeServerFailure, state, nil)
}
if len(records) == 0 {
return redis.errorANSWER(ctx, state.QName(), dns.RcodeSuccess, state, nil)
}
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative, m.Truncated = true, truncated
m.Answer = append(m.Answer, records...)
m.Extra = append(m.Extra, extra...)
w.WriteMsg(m)
return dns.RcodeSuccess, nil
}
// Name implements the Handler interface.
func (Redis) Name() string { return "redis" }
func (r Redis) errorANSWER(ctx context.Context, zone string, rcode int, state request.Request, err error) (int, error) {
m := new(dns.Msg)
m.SetRcode(state.Req, rcode)
m.Authoritative = true
stateNew := state.NewWithQuestion(state.Name(), dns.TypeSOA)
m.Ns, _ = r.SOA(ctx, zone, stateNew)
state.W.WriteMsg(m)
// Return success as the rcode to signal we have written to the client.
return dns.RcodeSuccess, err
}