mirror of
https://github.com/coredns/coredns.git
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more etcd stuff
This commit is contained in:
Miek Gieben
327
middleware/etcd/lookup.go
Normal file
327
middleware/etcd/lookup.go
Normal file
@@ -0,0 +1,327 @@
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package etcd
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/*
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func (s *server) AddressRecords(q dns.Question, name string, previousRecords []dns.RR, state middleware.State) (records []dns.RR, err error) {
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services, err := s.backend.Records(name, false)
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if err != nil {
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return nil, err
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}
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services = msg.Group(services)
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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 q.Name == 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(q.Name, dns.Fqdn(serv.Host))
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if len(previousRecords) > 7 {
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logf("CNAME lookup limit of 8 exceeded for %s", newRecord)
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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 s.isDuplicateCNAME(newRecord, previousRecords) {
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logf("CNAME loop detected for record %s", newRecord)
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continue
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}
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nextRecords, err := s.AddressRecords(dns.Question{Name: dns.Fqdn(serv.Host), Qtype: q.Qtype, Qclass: q.Qclass},
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strings.ToLower(dns.Fqdn(serv.Host)), append(previousRecords, newRecord), state)
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if err == nil {
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// 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(s.config.Domain, 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 := s.Lookup(target, q.Qtype, bufsize, dnssec)
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if e1 != nil {
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logf("incomplete CNAME chain: %s", e1)
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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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case ip.To4() != nil && (q.Qtype == dns.TypeA || both):
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records = append(records, serv.NewA(q.Name, ip.To4()))
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case ip.To4() == nil && (q.Qtype == dns.TypeAAAA || both):
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records = append(records, serv.NewAAAA(q.Name, 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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// NSRecords returns NS records from etcd.
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func (s *server) NSRecords(q dns.Question, state middleware.State) (records []dns.RR, extra []dns.RR, err error) {
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services, err := s.backend.Records(name, false)
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if err != nil {
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return nil, nil, err
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}
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services = msg.Group(services)
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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")
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case ip.To4() != nil:
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serv.Host = msg.Domain(serv.Key)
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records = append(records, serv.NewNS(q.Name, serv.Host))
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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 = msg.Domain(serv.Key)
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records = append(records, serv.NewNS(q.Name, serv.Host))
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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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// SRVRecords returns SRV records from etcd.
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// If the Target is not a name but an IP address, a name is created.
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func (s *server) SRVRecords(s middleware.State) (records []dns.RR, extra []dns.RR, err error) {
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services, err := s.backend.Records(name, false)
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if err != nil {
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return nil, nil, err
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}
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services = msg.Group(services)
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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(q.Name, 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(s.config.Domain, srv.Target) {
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m1, e1 := s.Lookup(srv.Target, dns.TypeA, bufsize, dnssec)
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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 = s.Lookup(srv.Target, dns.TypeAAAA, bufsize, dnssec)
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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
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// view.
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addr, e1 := s.AddressRecords(dns.Question{srv.Target, dns.ClassINET, dns.TypeA},
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srv.Target, nil, bufsize, dnssec, true)
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if e1 == nil {
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extra = append(extra, addr...)
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}
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case ip.To4() != nil:
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serv.Host = msg.Domain(serv.Key)
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srv := serv.NewSRV(q.Name, 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 = msg.Domain(serv.Key)
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srv := serv.NewSRV(q.Name, 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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// MXRecords returns MX records from etcd.
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// If the Target is not a name but an IP address, a name is created.
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func (s *server) MXRecords(q dns.Question, name string, s middleware.State) (records []dns.RR, extra []dns.RR, err error) {
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services, err := s.backend.Records(name, false)
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if err != nil {
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return nil, nil, err
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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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if !serv.Mail {
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continue
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}
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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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mx := serv.NewMX(q.Name)
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records = append(records, mx)
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if _, ok := lookup[mx.Mx]; ok {
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break
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}
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lookup[mx.Mx] = true
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if !dns.IsSubDomain(s.config.Domain, mx.Mx) {
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m1, e1 := s.Lookup(mx.Mx, dns.TypeA, bufsize, dnssec)
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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 = s.Lookup(mx.Mx, dns.TypeAAAA, bufsize, dnssec)
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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
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addr, e1 := s.AddressRecords(dns.Question{mx.Mx, dns.ClassINET, dns.TypeA},
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mx.Mx, nil, bufsize, dnssec, true)
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if e1 == nil {
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extra = append(extra, addr...)
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}
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case ip.To4() != nil:
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serv.Host = msg.Domain(serv.Key)
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records = append(records, serv.NewMX(q.Name))
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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 = msg.Domain(serv.Key)
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records = append(records, serv.NewMX(q.Name))
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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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func (s *server) CNAMERecords(q dns.Question, state middleware.State) (records []dns.RR, err error) {
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services, err := s.backend.Records(name, true)
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if err != nil {
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return nil, err
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}
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services = msg.Group(services)
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if len(services) > 0 {
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serv := services[0]
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if ip := net.ParseIP(serv.Host); ip == nil {
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records = append(records, serv.NewCNAME(q.Name, dns.Fqdn(serv.Host)))
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}
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}
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return records, nil
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}
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func (s *server) TXTRecords(q dns.Question, state middleware.State) (records []dns.RR, err error) {
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services, err := s.backend.Records(name, false)
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if err != nil {
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return nil, err
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}
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services = msg.Group(services)
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for _, serv := range services {
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if serv.Text == "" {
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continue
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}
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records = append(records, serv.NewTXT(q.Name))
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}
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return records, nil
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}
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func isDuplicateCNAME(r *dns.CNAME, records []dns.RR) bool {
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for _, rec := range records {
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if v, ok := rec.(*dns.CNAME); ok {
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if v.Target == r.Target {
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return true
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}
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}
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}
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return false
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}
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// Move to state.go somehow?
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func (s *server) NameError(req *dns.Msg) *dns.Msg {
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m := new(dns.Msg)
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m.SetRcode(req, dns.RcodeNameError)
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m.Ns = []dns.RR{s.NewSOA()}
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m.Ns[0].Header().Ttl = s.config.MinTtl
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return m
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}
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// overflowOrTruncated writes back an error to the client if the message does not fit.
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// It updates prometheus metrics. If something has been written to the client, true
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// will be returned.
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func (s *server) overflowOrTruncated(w dns.ResponseWriter, m *dns.Msg, bufsize int, sy metrics.System) bool {
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switch isTCP(w) {
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case true:
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if _, overflow := Fit(m, dns.MaxMsgSize, true); overflow {
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metrics.ReportErrorCount(m, sy)
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msgFail := s.ServerFailure(m)
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w.WriteMsg(msgFail)
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return true
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}
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case false:
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// Overflow with udp always results in TC.
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Fit(m, bufsize, false)
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metrics.ReportErrorCount(m, sy)
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if m.Truncated {
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w.WriteMsg(m)
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return true
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}
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}
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return false
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}
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// etcNameError return a NameError to the client if the error
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// returned from etcd has ErrorCode == 100.
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func isEtcdNameError(err error, s *server) bool {
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if e, ok := err.(etcd.Error); ok && e.Code == etcd.ErrorCodeKeyNotFound {
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return true
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}
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if err != nil {
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logf("error from backend: %s", err)
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}
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return false
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}
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*/
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