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-rw-r--r--middleware/kubernetes/lookup.go305
1 files changed, 305 insertions, 0 deletions
diff --git a/middleware/kubernetes/lookup.go b/middleware/kubernetes/lookup.go
new file mode 100644
index 000000000..1efec7475
--- /dev/null
+++ b/middleware/kubernetes/lookup.go
@@ -0,0 +1,305 @@
+package kubernetes
+
+import (
+ "fmt"
+ "math"
+ "net"
+ "time"
+
+ "github.com/miekg/coredns/middleware"
+ "github.com/miekg/coredns/middleware/kubernetes/msg"
+
+ "github.com/miekg/dns"
+)
+
+func (k Kubernetes) records(state middleware.State, exact bool) ([]msg.Service, error) {
+ services, err := k.Records(state.Name(), exact)
+ if err != nil {
+ return nil, err
+ }
+ // TODO: Do we want to support the SkyDNS (hacky) Group feature?
+ services = msg.Group(services)
+ return services, nil
+}
+
+func (k Kubernetes) A(zone string, state middleware.State, previousRecords []dns.RR) (records []dns.RR, err error) {
+ services, err := k.records(state, false)
+ if err != nil {
+ return nil, err
+ }
+
+ for _, serv := range services {
+ ip := net.ParseIP(serv.Host)
+ switch {
+ case ip == nil:
+ // TODO(miek): lowercasing? Should lowercase in everything see #85
+ if middleware.Name(state.Name()).Matches(dns.Fqdn(serv.Host)) {
+ // x CNAME x is a direct loop, don't add those
+ continue
+ }
+
+ newRecord := serv.NewCNAME(state.QName(), serv.Host)
+ if len(previousRecords) > 7 {
+ // don't add it, and just continue
+ continue
+ }
+ if isDuplicateCNAME(newRecord, previousRecords) {
+ continue
+ }
+
+ state1 := copyState(state, serv.Host, state.QType())
+ nextRecords, err := k.A(zone, state1, append(previousRecords, newRecord))
+
+ if err == nil {
+ // Not only have we found something we should add the CNAME and the IP addresses.
+ if len(nextRecords) > 0 {
+ records = append(records, newRecord)
+ records = append(records, nextRecords...)
+ }
+ continue
+ }
+ // This means we can not complete the CNAME, try to look else where.
+ target := newRecord.Target
+ if dns.IsSubDomain(zone, target) {
+ // We should already have found it
+ continue
+ }
+ m1, e1 := k.Proxy.Lookup(state, target, state.QType())
+ if e1 != nil {
+ continue
+ }
+ // Len(m1.Answer) > 0 here is well?
+ records = append(records, newRecord)
+ records = append(records, m1.Answer...)
+ continue
+ case ip.To4() != nil:
+ records = append(records, serv.NewA(state.QName(), ip.To4()))
+ case ip.To4() == nil:
+ // nodata?
+ }
+ }
+ return records, nil
+}
+
+func (k Kubernetes) AAAA(zone string, state middleware.State, previousRecords []dns.RR) (records []dns.RR, err error) {
+ services, err := k.records(state, false)
+ if err != nil {
+ return nil, err
+ }
+
+ for _, serv := range services {
+ ip := net.ParseIP(serv.Host)
+ switch {
+ case ip == nil:
+ // Try to resolve as CNAME if it's not an IP, but only if we don't create loops.
+ if middleware.Name(state.Name()).Matches(dns.Fqdn(serv.Host)) {
+ // x CNAME x is a direct loop, don't add those
+ continue
+ }
+
+ newRecord := serv.NewCNAME(state.QName(), serv.Host)
+ if len(previousRecords) > 7 {
+ // don't add it, and just continue
+ continue
+ }
+ if isDuplicateCNAME(newRecord, previousRecords) {
+ continue
+ }
+
+ state1 := copyState(state, serv.Host, state.QType())
+ nextRecords, err := k.AAAA(zone, state1, append(previousRecords, newRecord))
+
+ if err == nil {
+ // Not only have we found something we should add the CNAME and the IP addresses.
+ if len(nextRecords) > 0 {
+ records = append(records, newRecord)
+ records = append(records, nextRecords...)
+ }
+ continue
+ }
+ // This means we can not complete the CNAME, try to look else where.
+ target := newRecord.Target
+ if dns.IsSubDomain(zone, target) {
+ // We should already have found it
+ continue
+ }
+ m1, e1 := k.Proxy.Lookup(state, target, state.QType())
+ if e1 != nil {
+ continue
+ }
+ // Len(m1.Answer) > 0 here is well?
+ records = append(records, newRecord)
+ records = append(records, m1.Answer...)
+ continue
+ // both here again
+ case ip.To4() != nil:
+ // nada?
+ case ip.To4() == nil:
+ records = append(records, serv.NewAAAA(state.QName(), ip.To16()))
+ }
+ }
+ return records, nil
+}
+
+// SRV returns SRV records from etcd.
+// If the Target is not a name but an IP address, a name is created on the fly.
+func (k Kubernetes) SRV(zone string, state middleware.State) (records []dns.RR, extra []dns.RR, err error) {
+ services, err := k.records(state, false)
+ if err != nil {
+ return nil, nil, err
+ }
+
+ // Looping twice to get the right weight vs priority
+ w := make(map[int]int)
+ for _, serv := range services {
+ weight := 100
+ if serv.Weight != 0 {
+ weight = serv.Weight
+ }
+ if _, ok := w[serv.Priority]; !ok {
+ w[serv.Priority] = weight
+ continue
+ }
+ w[serv.Priority] += weight
+ }
+ lookup := make(map[string]bool)
+ for _, serv := range services {
+ w1 := 100.0 / float64(w[serv.Priority])
+ if serv.Weight == 0 {
+ w1 *= 100
+ } else {
+ w1 *= float64(serv.Weight)
+ }
+ weight := uint16(math.Floor(w1))
+ ip := net.ParseIP(serv.Host)
+ switch {
+ case ip == nil:
+ srv := serv.NewSRV(state.QName(), weight)
+ records = append(records, srv)
+
+ if _, ok := lookup[srv.Target]; ok {
+ break
+ }
+
+ lookup[srv.Target] = true
+
+ if !dns.IsSubDomain(zone, srv.Target) {
+ m1, e1 := k.Proxy.Lookup(state, srv.Target, dns.TypeA)
+ if e1 == nil {
+ extra = append(extra, m1.Answer...)
+ }
+ m1, e1 = k.Proxy.Lookup(state, srv.Target, dns.TypeAAAA)
+ if e1 == nil {
+ // If we have seen CNAME's we *assume* that they are already added.
+ for _, a := range m1.Answer {
+ if _, ok := a.(*dns.CNAME); !ok {
+ extra = append(extra, a)
+ }
+ }
+ }
+ break
+ }
+ // Internal name, we should have some info on them, either v4 or v6
+ // Clients expect a complete answer, because we are a recursor in their view.
+ state1 := copyState(state, srv.Target, dns.TypeA)
+ addr, e1 := k.A(zone, state1, nil)
+ if e1 == nil {
+ extra = append(extra, addr...)
+ }
+ // k.AAA(zone, state1, nil) as well...?
+ case ip.To4() != nil:
+ serv.Host = k.Domain(serv.Key)
+ srv := serv.NewSRV(state.QName(), weight)
+
+ records = append(records, srv)
+ extra = append(extra, serv.NewA(srv.Target, ip.To4()))
+ case ip.To4() == nil:
+ serv.Host = k.Domain(serv.Key)
+ srv := serv.NewSRV(state.QName(), weight)
+
+ records = append(records, srv)
+ extra = append(extra, serv.NewAAAA(srv.Target, ip.To16()))
+ }
+ }
+ return records, extra, nil
+}
+
+// Returning MX records from kubernetes not implemented.
+func (k Kubernetes) MX(zone string, state middleware.State) (records []dns.RR, extra []dns.RR, err error) {
+ return nil, nil, err
+}
+
+// Returning CNAME records from kubernetes not implemented.
+func (k Kubernetes) CNAME(zone string, state middleware.State) (records []dns.RR, err error) {
+ return nil, err
+}
+
+// Returning TXT records from kubernetes not implemented.
+func (k Kubernetes) TXT(zone string, state middleware.State) (records []dns.RR, err error) {
+ return nil, err
+}
+
+func (k Kubernetes) NS(zone string, state middleware.State) (records, extra []dns.RR, err error) {
+ // NS record for this zone live in a special place, ns.dns.<zone>. Fake our lookup.
+ // only a tad bit fishy...
+ old := state.QName()
+
+ state.Clear()
+ state.Req.Question[0].Name = "ns.dns." + zone
+ services, err := k.records(state, false)
+ if err != nil {
+ return nil, nil, err
+ }
+ // ... and reset
+ state.Req.Question[0].Name = old
+
+ for _, serv := range services {
+ ip := net.ParseIP(serv.Host)
+ switch {
+ case ip == nil:
+ return nil, nil, fmt.Errorf("NS record must be an IP address: %s", serv.Host)
+ case ip.To4() != nil:
+ serv.Host = k.Domain(serv.Key)
+ records = append(records, serv.NewNS(state.QName()))
+ extra = append(extra, serv.NewA(serv.Host, ip.To4()))
+ case ip.To4() == nil:
+ serv.Host = k.Domain(serv.Key)
+ records = append(records, serv.NewNS(state.QName()))
+ extra = append(extra, serv.NewAAAA(serv.Host, ip.To16()))
+ }
+ }
+ return records, extra, nil
+}
+
+// SOA Record returns a SOA record.
+func (k Kubernetes) SOA(zone string, state middleware.State) *dns.SOA {
+ header := dns.RR_Header{Name: zone, Rrtype: dns.TypeSOA, Ttl: 300, Class: dns.ClassINET}
+ return &dns.SOA{Hdr: header,
+ Mbox: "hostmaster." + zone,
+ Ns: "ns.dns." + zone,
+ Serial: uint32(time.Now().Unix()),
+ Refresh: 7200,
+ Retry: 1800,
+ Expire: 86400,
+ Minttl: 60,
+ }
+}
+
+// TODO(miek): DNSKEY and friends... intercepted by the DNSSEC middleware?
+
+func isDuplicateCNAME(r *dns.CNAME, records []dns.RR) bool {
+ for _, rec := range records {
+ if v, ok := rec.(*dns.CNAME); ok {
+ if v.Target == r.Target {
+ return true
+ }
+ }
+ }
+ return false
+}
+
+func copyState(state middleware.State, target string, typ uint16) middleware.State {
+ state1 := middleware.State{W: state.W, Req: state.Req.Copy()}
+ state1.Req.Question[0] = dns.Question{dns.Fqdn(target), dns.ClassINET, typ}
+ return state1
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-07-30 03:44:39 +0000