func (s *server) CNAMERecords(q dns.Question, name string) (records []dns.RR, err error) { path, _ := msg.PathWithWildcard(name) // no wildcards here r, err := get(s.client, path, true) if err != nil { return nil, err } if !r.Node.Dir { serv := new(msg.Service) if err := json.Unmarshal([]byte(r.Node.Value), serv); err != nil { s.config.log.Infof("failed to parse json: %s", err.Error()) return nil, err } ip := net.ParseIP(serv.Host) ttl := s.calculateTtl(r.Node, serv) serv.Key = r.Node.Key serv.Ttl = ttl if ip == nil { records = append(records, serv.NewCNAME(q.Name, dns.Fqdn(serv.Host))) } } return records, nil }
func (s *server) AddressRecords(q dns.Question, name string, previousRecords []dns.RR) (records []dns.RR, err error) { path, star := msg.PathWithWildcard(name) r, err := get(s.client, path, true) if err != nil { return nil, err } if !r.Node.Dir { // single element serv := new(msg.Service) if err := json.Unmarshal([]byte(r.Node.Value), serv); err != nil { s.config.log.Infof("failed to parse json: %s", err.Error()) return nil, err } ip := net.ParseIP(serv.Host) ttl := s.calculateTtl(r.Node, serv) serv.Ttl = ttl serv.Key = r.Node.Key switch { case ip == nil: // Try to resolve as CNAME if it's not an IP. newRecord := serv.NewCNAME(q.Name, dns.Fqdn(serv.Host)) if len(previousRecords) > 7 { s.config.log.Errorf("CNAME lookup limit of 8 exceeded for %s", newRecord) return nil, fmt.Errorf("exceeded CNAME lookup limit") } if s.isDuplicateCNAME(newRecord, previousRecords) { s.config.log.Errorf("CNAME loop detected for record %s", newRecord) return nil, fmt.Errorf("detected CNAME loop") } records = append(records, newRecord) nextRecords, err := s.AddressRecords(dns.Question{Name: dns.Fqdn(serv.Host), Qtype: q.Qtype, Qclass: q.Qclass}, strings.ToLower(dns.Fqdn(serv.Host)), append(previousRecords, newRecord)) if err != nil { // This means we can not complete the CNAME, this is OK, but // if we return an error this will trigger an NXDOMAIN. // We also don't want to return the CNAME, because of the // no other data rule. So return nothing and let NODATA // kick in (via a hack). return records, fmt.Errorf("incomplete CNAME chain") } records = append(records, nextRecords...) case ip.To4() != nil && q.Qtype == dns.TypeA: records = append(records, serv.NewA(q.Name, ip.To4())) case ip.To4() == nil && q.Qtype == dns.TypeAAAA: records = append(records, serv.NewAAAA(q.Name, ip.To16())) } return records, nil } nodes, err := s.loopNodes(&r.Node.Nodes, strings.Split(msg.Path(name), "/"), star, nil) if err != nil { s.config.log.Infof("failed to parse json: %s", err.Error()) return nil, err } for _, serv := range nodes { ip := net.ParseIP(serv.Host) switch { case ip == nil: // TODO: deduplicate with above code // Try to resolve as CNAME if it's not an IP. newRecord := serv.NewCNAME(q.Name, dns.Fqdn(serv.Host)) if len(previousRecords) > 7 { s.config.log.Errorf("CNAME lookup limit of 8 exceeded for %s", newRecord) return nil, fmt.Errorf("exceeded CNAME lookup limit") } if s.isDuplicateCNAME(newRecord, previousRecords) { s.config.log.Errorf("CNAME loop detected for record %s", newRecord) return nil, fmt.Errorf("detected CNAME loop") } records = append(records, newRecord) nextRecords, err := s.AddressRecords(dns.Question{Name: dns.Fqdn(serv.Host), Qtype: q.Qtype, Qclass: q.Qclass}, strings.ToLower(dns.Fqdn(serv.Host)), append(previousRecords, newRecord)) if err != nil { // This means we can not complete the CNAME, this is OK, but // if we return an error this will trigger an NXDOMAIN. // We also don't want to return the CNAME, because of the // no other data rule. So return nothing and let NODATA // kick in (via a hack). return records, fmt.Errorf("incomplete CNAME chain") } records = append(records, nextRecords...) case ip.To4() != nil && q.Qtype == dns.TypeA: records = append(records, serv.NewA(q.Name, ip.To4())) case ip.To4() == nil && q.Qtype == dns.TypeAAAA: records = append(records, serv.NewAAAA(q.Name, ip.To16())) } } if s.config.RoundRobin { switch l := len(records); l { case 2: if dns.Id()%2 == 0 { records[0], records[1] = records[1], records[0] } default: // Do a minimum of l swap, maximum of 4l swaps for j := 0; j < l*(int(dns.Id())%4+1); j++ { q := int(dns.Id()) % l p := int(dns.Id()) % l if q == p { p = (p + 1) % l } records[q], records[p] = records[p], records[q] } } } return records, nil }