forked from coredns/coredns
/
lookup.go
321 lines (290 loc) · 8.92 KB
/
lookup.go
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package kubernetes
import (
"fmt"
"math"
"net"
"time"
"github.com/miekg/coredns/middleware"
"github.com/miekg/coredns/middleware/etcd/msg"
"github.com/miekg/coredns/middleware/pkg/dnsutil"
"github.com/miekg/coredns/request"
"github.com/miekg/dns"
)
func (k Kubernetes) records(state request.Request, 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
}
// A returns A records from kubernetes or an error.
func (k Kubernetes) A(zone string, state request.Request, 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 dnsutil.DuplicateCNAME(newRecord, previousRecords) {
continue
}
state1 := state.NewWithQuestion(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
}
mes, err := k.Proxy.Lookup(state, target, state.QType())
if err != nil {
continue
}
// Len(mes.Answer) > 0 here is well?
records = append(records, newRecord)
records = append(records, mes.Answer...)
continue
case ip.To4() != nil:
records = append(records, serv.NewA(state.QName(), ip.To4()))
case ip.To4() == nil:
// nodata?
}
}
return records, nil
}
// AAAA returns AAAA records from kubernetes or an error.
func (k Kubernetes) AAAA(zone string, state request.Request, 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 dnsutil.DuplicateCNAME(newRecord, previousRecords) {
continue
}
state1 := state.NewWithQuestion(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 kubernetes.
// 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
// the additional section.
func (k Kubernetes) SRV(zone string, state request.Request) (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 := state.NewWithQuestion(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 = 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 = 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
}
// MX returns MX records from kubernetes. Not implemented!
func (k Kubernetes) MX(zone string, state request.Request) (records []dns.RR, extra []dns.RR, err error) {
return nil, nil, err
}
// CNAME returns CNAME records from kubernetes. Not implemented!
func (k Kubernetes) CNAME(zone string, state request.Request) (records []dns.RR, err error) {
return nil, err
}
// TXT returns TXT records from kubernetes. Not implemented!
func (k Kubernetes) TXT(zone string, state request.Request) (records []dns.RR, err error) {
return nil, err
}
// NS returns NS records from kubernetes.
func (k Kubernetes) NS(zone string, state request.Request) (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 = serv.Key
records = append(records, serv.NewNS(state.QName()))
extra = append(extra, serv.NewA(serv.Host, ip.To4()))
case ip.To4() == nil:
serv.Host = 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 from kubernetes.
func (k Kubernetes) SOA(zone string, state request.Request) *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,
}
}
// PTR Record returns PTR records from kubernetes.
func (k Kubernetes) PTR(zone string, state request.Request) ([]dns.RR, error) {
reverseIP := dnsutil.ExtractAddressFromReverse(state.Name())
if reverseIP == "" {
return nil, fmt.Errorf("does not support reverse lookup for %s", state.QName())
}
records := make([]dns.RR, 1)
services, err := k.records(state, false)
if err != nil {
return nil, err
}
for _, serv := range services {
ip := net.ParseIP(serv.Host)
if reverseIP != serv.Host {
continue
}
switch {
case ip.To4() != nil:
records = append(records, serv.NewPTR(state.QName(), ip.To4().String()))
break
case ip.To4() == nil:
// nodata?
}
}
return records, nil
}