138 lines
3.5 KiB
Go
138 lines
3.5 KiB
Go
package etcd
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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/etcd/msg"
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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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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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name := state.Name()
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if e.Debug {
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if debug := isDebug(name); debug != "" {
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e.debug = r.Question[0].Name
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state.Clear()
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state.Req.Question[0].Name = debug
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}
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}
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// We need to check stubzones first, because we may get a request for a zone we
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// are not auth. for *but* do have a stubzone forward for. If we do the stubzone
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// handler will handle the request.
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if e.Stubmap != nil && len(*e.Stubmap) > 0 {
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for zone := range *e.Stubmap {
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if middleware.Name(zone).Matches(name) {
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stub := Stub{Etcd: e, Zone: zone}
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return stub.ServeDNS(ctx, w, r)
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}
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}
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}
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zone := middleware.Zones(e.Zones).Matches(state.Name())
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if zone == "" {
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if e.Next == nil {
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return dns.RcodeServerFailure, nil
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}
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return e.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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debug []msg.Service
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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, debug, err = e.A(zone, state, nil)
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case "AAAA":
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records, debug, err = e.AAAA(zone, state, nil)
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case "TXT":
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records, debug, err = e.TXT(zone, state)
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case "CNAME":
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records, debug, err = e.CNAME(zone, state)
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case "PTR":
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records, debug, err = e.PTR(zone, state)
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case "MX":
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records, extra, debug, err = e.MX(zone, state)
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case "SRV":
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records, extra, debug, err = e.SRV(zone, state)
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case "SOA":
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records, debug, err = e.SOA(zone, state)
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case "NS":
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if state.Name() == zone {
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records, extra, debug, err = e.NS(zone, state)
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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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_, debug, err = e.A(zone, state, nil)
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}
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if e.debug != "" {
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// Substitute this name with the original when we return the request.
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state.Clear()
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state.Req.Question[0].Name = e.debug
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}
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if isEtcdNameError(err) {
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return e.Err(zone, dns.RcodeNameError, state, debug, err)
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}
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if err != nil {
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return e.Err(zone, dns.RcodeServerFailure, state, debug, err)
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}
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if len(records) == 0 {
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return e.Err(zone, dns.RcodeSuccess, state, debug, err)
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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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m.Answer = append(m.Answer, records...)
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m.Extra = append(m.Extra, extra...)
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if e.debug != "" {
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m.Extra = append(m.Extra, servicesToTxt(debug)...)
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}
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m = 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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// Err write an error response to the client.
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func (e Etcd) Err(zone string, rcode int, state middleware.State, debug []msg.Service, err error) (int, error) {
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m := new(dns.Msg)
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m.SetRcode(state.Req, rcode)
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m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
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m.Ns, _, _ = e.SOA(zone, state)
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if e.debug != "" {
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m.Extra = servicesToTxt(debug)
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txt := errorToTxt(err)
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if txt != nil {
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m.Extra = append(m.Extra, errorToTxt(err))
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}
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}
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state.SizeAndDo(m)
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state.W.WriteMsg(m)
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// Return success as the rcode to signal we have written to the client.
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return dns.RcodeSuccess, nil
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}
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func dedup(m *dns.Msg) *dns.Msg {
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// TODO(miek): expensive!
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m.Answer = dns.Dedup(m.Answer, nil)
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m.Ns = dns.Dedup(m.Ns, nil)
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m.Extra = dns.Dedup(m.Extra, nil)
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return m
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}
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