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27d893cf33
* Add ServiceBackend interface This adds a ServiceBackend interface that is shared between etcd/etcd3 (later) and kubernetes, leading to a massive reduction in code. When returning the specific records from their backend. Fixes #273
105 lines
3.1 KiB
Go
105 lines
3.1 KiB
Go
package kubernetes
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import (
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"fmt"
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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, fmt.Errorf("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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// TODO: find an alternative to this block
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// TODO(miek): Why is this even here, why does the path Etcd takes not work?
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// Should be a "case PTR" below. I would also like to use middleware.PTR for this.
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ip := dnsutil.ExtractAddressFromReverse(state.Name())
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if ip != "" {
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records := k.getServiceRecordForIP(ip, state.Name())
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if len(records) > 0 {
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srvPTR := &records[0]
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m.Answer = append(m.Answer, srvPTR.NewPTR(state.QName(), ip))
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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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}
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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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if k.Next == nil {
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return dns.RcodeServerFailure, nil
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}
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return k.Next.ServeDNS(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 "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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