ServiceBackend interface (#369)
* 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
This commit is contained in:
Miek Gieben
GitHub
parent
81d5baee28
commit
27d893cf33
15 changed files with 273 additions and 503 deletions
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@ -2,11 +2,8 @@ package kubernetes
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import (
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"fmt"
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"math"
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"net"
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"time"
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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/coredns/middleware/pkg/dnsutil"
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"github.com/miekg/coredns/request"
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@ -19,278 +16,10 @@ func (k Kubernetes) records(state request.Request, exact bool) ([]msg.Service, e
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if err != nil {
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return nil, err
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}
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// TODO: Do we want to support the SkyDNS (hacky) Group feature?
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services = msg.Group(services)
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return services, nil
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}
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// A returns A records from kubernetes or an error.
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func (k Kubernetes) A(zone string, state request.Request, previousRecords []dns.RR) (records []dns.RR, err error) {
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services, err := k.records(state, false)
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if err != nil {
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return nil, err
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}
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for _, serv := range services {
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ip := net.ParseIP(serv.Host)
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switch {
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case ip == nil:
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// TODO(miek): lowercasing? Should lowercase in everything see #85
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if middleware.Name(state.Name()).Matches(dns.Fqdn(serv.Host)) {
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// x CNAME x is a direct loop, don't add those
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continue
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}
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newRecord := serv.NewCNAME(state.QName(), serv.Host)
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if len(previousRecords) > 7 {
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// don't add it, and just continue
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continue
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}
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if dnsutil.DuplicateCNAME(newRecord, previousRecords) {
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continue
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}
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state1 := state.NewWithQuestion(serv.Host, state.QType())
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nextRecords, err := k.A(zone, state1, append(previousRecords, newRecord))
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if err == nil {
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// Not only have we found something we should add the CNAME and the IP addresses.
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if len(nextRecords) > 0 {
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records = append(records, newRecord)
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records = append(records, nextRecords...)
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}
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continue
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}
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// This means we can not complete the CNAME, try to look else where.
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target := newRecord.Target
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if dns.IsSubDomain(zone, target) {
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// We should already have found it
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continue
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}
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mes, err := k.Proxy.Lookup(state, target, state.QType())
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if err != nil {
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continue
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}
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// Len(mes.Answer) > 0 here is well?
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records = append(records, newRecord)
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records = append(records, mes.Answer...)
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continue
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case ip.To4() != nil:
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records = append(records, serv.NewA(state.QName(), ip.To4()))
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case ip.To4() == nil:
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// nodata?
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}
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}
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return records, nil
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}
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// AAAA returns AAAA records from kubernetes or an error.
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func (k Kubernetes) AAAA(zone string, state request.Request, previousRecords []dns.RR) (records []dns.RR, err error) {
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services, err := k.records(state, false)
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if err != nil {
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return nil, err
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}
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for _, serv := range services {
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ip := net.ParseIP(serv.Host)
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switch {
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case ip == nil:
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// Try to resolve as CNAME if it's not an IP, but only if we don't create loops.
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if middleware.Name(state.Name()).Matches(dns.Fqdn(serv.Host)) {
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// x CNAME x is a direct loop, don't add those
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continue
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}
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newRecord := serv.NewCNAME(state.QName(), serv.Host)
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if len(previousRecords) > 7 {
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// don't add it, and just continue
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continue
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}
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if dnsutil.DuplicateCNAME(newRecord, previousRecords) {
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continue
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}
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state1 := state.NewWithQuestion(serv.Host, state.QType())
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nextRecords, err := k.AAAA(zone, state1, append(previousRecords, newRecord))
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if err == nil {
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// Not only have we found something we should add the CNAME and the IP addresses.
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if len(nextRecords) > 0 {
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records = append(records, newRecord)
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records = append(records, nextRecords...)
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}
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continue
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}
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// This means we can not complete the CNAME, try to look else where.
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target := newRecord.Target
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if dns.IsSubDomain(zone, target) {
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// We should already have found it
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continue
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}
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m1, e1 := k.Proxy.Lookup(state, target, state.QType())
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if e1 != nil {
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continue
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}
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// Len(m1.Answer) > 0 here is well?
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records = append(records, newRecord)
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records = append(records, m1.Answer...)
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continue
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// both here again
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case ip.To4() != nil:
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// nada?
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case ip.To4() == nil:
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records = append(records, serv.NewAAAA(state.QName(), ip.To16()))
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}
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}
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return records, nil
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}
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// SRV returns SRV records from kubernetes.
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// If the Target is not a name but an IP address, a name is created on the fly and the IP address is put in
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// the additional section.
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func (k Kubernetes) SRV(zone string, state request.Request) (records []dns.RR, extra []dns.RR, err error) {
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services, err := k.records(state, false)
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if err != nil {
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return nil, nil, err
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}
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// Looping twice to get the right weight vs priority
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w := make(map[int]int)
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for _, serv := range services {
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weight := 100
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if serv.Weight != 0 {
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weight = serv.Weight
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}
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if _, ok := w[serv.Priority]; !ok {
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w[serv.Priority] = weight
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continue
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}
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w[serv.Priority] += weight
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}
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lookup := make(map[string]bool)
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for _, serv := range services {
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w1 := 100.0 / float64(w[serv.Priority])
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if serv.Weight == 0 {
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w1 *= 100
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} else {
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w1 *= float64(serv.Weight)
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}
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weight := uint16(math.Floor(w1))
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ip := net.ParseIP(serv.Host)
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switch {
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case ip == nil:
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srv := serv.NewSRV(state.QName(), weight)
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records = append(records, srv)
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if _, ok := lookup[srv.Target]; ok {
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break
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}
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lookup[srv.Target] = true
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if !dns.IsSubDomain(zone, srv.Target) {
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m1, e1 := k.Proxy.Lookup(state, srv.Target, dns.TypeA)
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if e1 == nil {
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extra = append(extra, m1.Answer...)
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}
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m1, e1 = k.Proxy.Lookup(state, srv.Target, dns.TypeAAAA)
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if e1 == nil {
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// If we have seen CNAME's we *assume* that they are already added.
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for _, a := range m1.Answer {
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if _, ok := a.(*dns.CNAME); !ok {
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extra = append(extra, a)
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}
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}
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}
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break
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}
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// Internal name, we should have some info on them, either v4 or v6
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// Clients expect a complete answer, because we are a recursor in their view.
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state1 := state.NewWithQuestion(srv.Target, dns.TypeA)
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addr, e1 := k.A(zone, state1, nil)
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if e1 == nil {
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extra = append(extra, addr...)
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}
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// k.AAA(zone, state1, nil) as well...?
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case ip.To4() != nil:
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serv.Host = serv.Key
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srv := serv.NewSRV(state.QName(), weight)
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records = append(records, srv)
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extra = append(extra, serv.NewA(srv.Target, ip.To4()))
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case ip.To4() == nil:
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serv.Host = serv.Key
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srv := serv.NewSRV(state.QName(), weight)
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records = append(records, srv)
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extra = append(extra, serv.NewAAAA(srv.Target, ip.To16()))
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}
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}
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return records, extra, nil
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}
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// MX returns MX records from kubernetes. Not implemented!
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func (k Kubernetes) MX(zone string, state request.Request) (records []dns.RR, extra []dns.RR, err error) {
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return nil, nil, err
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}
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// CNAME returns CNAME records from kubernetes. Not implemented!
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func (k Kubernetes) CNAME(zone string, state request.Request) (records []dns.RR, err error) {
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return nil, err
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}
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// TXT returns TXT records from kubernetes. Not implemented!
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func (k Kubernetes) TXT(zone string, state request.Request) (records []dns.RR, err error) {
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return nil, err
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}
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// NS returns NS records from kubernetes.
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func (k Kubernetes) NS(zone string, state request.Request) (records, extra []dns.RR, err error) {
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// NS record for this zone live in a special place, ns.dns.<zone>. Fake our lookup.
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// only a tad bit fishy...
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old := state.QName()
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state.Clear()
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state.Req.Question[0].Name = "ns.dns." + zone
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services, err := k.records(state, false)
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if err != nil {
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return nil, nil, err
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}
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// ... and reset
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state.Req.Question[0].Name = old
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for _, serv := range services {
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ip := net.ParseIP(serv.Host)
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switch {
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case ip == nil:
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return nil, nil, fmt.Errorf("NS record must be an IP address: %s", serv.Host)
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case ip.To4() != nil:
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serv.Host = serv.Key
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records = append(records, serv.NewNS(state.QName()))
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extra = append(extra, serv.NewA(serv.Host, ip.To4()))
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case ip.To4() == nil:
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serv.Host = serv.Key
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records = append(records, serv.NewNS(state.QName()))
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extra = append(extra, serv.NewAAAA(serv.Host, ip.To16()))
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}
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}
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return records, extra, nil
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}
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// SOA Record returns a SOA record from kubernetes.
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func (k Kubernetes) SOA(zone string, state request.Request) *dns.SOA {
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header := dns.RR_Header{Name: zone, Rrtype: dns.TypeSOA, Ttl: 300, Class: dns.ClassINET}
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return &dns.SOA{Hdr: header,
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Mbox: "hostmaster." + zone,
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Ns: "ns.dns." + zone,
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Serial: uint32(time.Now().Unix()),
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Refresh: 7200,
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Retry: 1800,
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Expire: 86400,
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Minttl: 60,
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}
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}
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// PTR Record returns PTR records from kubernetes.
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func (k Kubernetes) PTR(zone string, state request.Request) ([]dns.RR, error) {
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reverseIP := dnsutil.ExtractAddressFromReverse(state.Name())
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