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https://github.com/coredns/coredns.git
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c4ab98c6e3
This checks if the next middleware to be called is nil, and if so returns ServerFailure and an error. This makes the next calling more robust and saves some lines of code. Also prefix the error with the name of the middleware to aid in debugging.
86 lines
2.6 KiB
Go
86 lines
2.6 KiB
Go
package kubernetes
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import (
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"errors"
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"github.com/miekg/coredns/middleware"
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"github.com/miekg/coredns/middleware/pkg/dnsutil"
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"github.com/miekg/coredns/request"
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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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// ServeDNS implements the middleware.Handler interface.
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func (k Kubernetes) 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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if state.QClass() != dns.ClassINET {
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return dns.RcodeServerFailure, middleware.Error(k.Name(), errors.New("can only deal with ClassINET"))
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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, m.RecursionAvailable, m.Compress = true, true, true
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// Check that query matches one of the zones served by this middleware,
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// otherwise delegate to the next in the pipeline.
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zone := middleware.Zones(k.Zones).Matches(state.Name())
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if zone == "" {
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return middleware.NextOrFailure(k.Name(), k.Next, ctx, w, r)
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}
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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 = middleware.A(&k, zone, state, nil, middleware.Options{}) // Hmm wrt to '&k'
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case "AAAA":
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records, _, err = middleware.AAAA(&k, zone, state, nil, middleware.Options{})
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case "TXT":
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records, _, err = middleware.TXT(&k, zone, state, middleware.Options{})
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case "CNAME":
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records, _, err = middleware.CNAME(&k, zone, state, middleware.Options{})
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case "PTR":
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records, _, err = middleware.PTR(&k, zone, state, middleware.Options{})
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case "MX":
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records, extra, _, err = middleware.MX(&k, zone, state, middleware.Options{})
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case "SRV":
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records, extra, _, err = middleware.SRV(&k, zone, state, middleware.Options{})
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case "SOA":
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records, _, err = middleware.SOA(&k, zone, state, middleware.Options{})
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case "NS":
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if state.Name() == zone {
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records, extra, _, err = middleware.NS(&k, zone, state, middleware.Options{})
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break
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}
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fallthrough
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default:
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// Do a fake A lookup, so we can distinguish between NODATA and NXDOMAIN
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_, _, err = middleware.A(&k, zone, state, nil, middleware.Options{})
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}
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if k.IsNameError(err) {
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return middleware.BackendError(&k, zone, dns.RcodeNameError, state, nil /*debug*/, err, middleware.Options{})
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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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return middleware.BackendError(&k, zone, dns.RcodeSuccess, state, nil /*debug*/, nil, middleware.Options{})
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}
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m.Answer = append(m.Answer, records...)
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m.Extra = append(m.Extra, extra...)
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m = dnsutil.Dedup(m)
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state.SizeAndDo(m)
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m, _ = state.Scrub(m)
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w.WriteMsg(m)
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return dns.RcodeSuccess, nil
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}
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// Name implements the Handler interface.
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func (k Kubernetes) Name() string { return "kubernetes" }
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