m-dns/zone/zone.go

package zone

import (
	"fmt"
	"net"

	"git.giaever.org/joachimmg/m-dns/config"
	"git.giaever.org/joachimmg/m-dns/errors"
	"git.giaever.org/joachimmg/m-dns/host"
	"github.com/miekg/dns"
)

type Zone interface {
	Records(q dns.Question)
}

type ZoneRecord struct {
	Instance host.HostString
	TXT      []string

	sAddr string
	iAddr string
	eAddr string

	*host.Host
}

func New(instance, service, domain, hostname string, port int, ips []net.IP, txt []string) (*ZoneRecord, error) {
	zr := new(ZoneRecord)
	zr.Host = new(host.Host)

	if len(instance) == 0 {
		return nil, errors.ZoneInstanseIsEmpty
	}

	zr.Instance = host.HostString(instance)

	if err := zr.SetService(service); err != nil {
		return nil, err
	}

	if err := zr.SetDomain(domain); err != nil {
		return nil, err
	}

	if err := zr.SetHostname(hostname); err != nil {
		return nil, err
	}

	if err := zr.SetPort(port); err != nil {
		return nil, err
	}

	zr.TXT = txt

	zr.sAddr = fmt.Sprintf("%s.%s.",
		zr.GetService().TrimDot(),
		zr.GetDomain().TrimDot(),
	)
	zr.iAddr = fmt.Sprintf("%s.%s.%s.",
		zr.Instance.TrimDot,
		zr.GetService().TrimDot(),
		zr.GetDomain().TrimDot(),
	)
	zr.eAddr = fmt.Sprintf("_services._dns-ds._udp.%s.",
		zr.GetDomain().TrimDot(),
	)
	return zr, nil
}

func (zr *ZoneRecord) Records(q dns.Question) []dns.RR {
	switch q.Name {
	case zr.sAddr:
		return zr.sRecords(q)
	case zr.iAddr:
		return zr.iRecords(q)
	case zr.eAddr:
		return zr.sEnum(q)
	case zr.GetHostname().String():
		switch q.Qtype {
		case dns.TypeA, dns.TypeAAAA:
			return zr.iRecords(q)
		}
		fallthrough
	default:
		return nil
	}
}

func (zr *ZoneRecord) sRecords(q dns.Question) []dns.RR {
	switch q.Qtype {
	case dns.TypeANY, dns.TypePTR:
		sr := []dns.RR{
			&dns.PTR{
				Hdr: dns.RR_Header{
					Name:   q.Name,
					Rrtype: dns.TypePTR,
					Class:  dns.ClassINET,
					Ttl:    config.DefaultTTL,
				},
				Ptr: zr.iAddr,
			},
		}

		return append(sr, zr.Records(
			dns.Question{
				Name:  zr.iAddr,
				Qtype: dns.TypeANY,
			},
		)...)

	default:
		return nil
	}
}

func (zr *ZoneRecord) iRecords(q dns.Question) []dns.RR {
	switch q.Qtype {
	case dns.TypeANY:
		ir := zr.Records(
			dns.Question{
				Name:  zr.iAddr,
				Qtype: dns.TypeSRV,
			},
		)

		return append(ir, zr.Records(
			dns.Question{
				Name:  zr.iAddr,
				Qtype: dns.TypeTXT,
			},
		)...)
	case dns.TypeA:
		var ir []dns.RR
		for _, ip := range zr.GetIPs() {
			switch ip.Type() {
			case host.IPv4:
				ir = append(ir, &dns.A{
					Hdr: dns.RR_Header{
						Name:   zr.GetHostname().String(),
						Rrtype: dns.TypeA,
						Class:  dns.ClassINET,
						Ttl:    config.DefaultTTL,
					},
				})
			case host.IPv6:
				continue
			}
		}
		return ir
	case dns.TypeAAAA:
		var ir []dns.RR
		for _, ip := range zr.GetIPs() {
			switch ip.Type() {
			case host.IPv4:
				continue
			case host.IPv6:
				ir = append(ir, &dns.AAAA{
					Hdr: dns.RR_Header{
						Name:   zr.GetHostname().String(),
						Rrtype: dns.TypeAAAA,
						Class:  dns.ClassINET,
						Ttl:    config.DefaultTTL,
					},
					AAAA: ip.AsIP().To16(),
				})
			}
		}
		return ir
	case dns.TypeSRV:
		ir := []dns.RR{
			&dns.SRV{
				Hdr: dns.RR_Header{
					Name:   q.Name,
					Rrtype: dns.TypeSRV,
					Class:  dns.ClassINET,
					Ttl:    config.DefaultTTL,
				},
				Priority: 10,
				Weight:   1,
				Port:     zr.GetPort().Uint16(),
				Target:   zr.GetHostname().String(),
			},
		}

		ir = append(ir, zr.Records(
			dns.Question{
				Name:  zr.iAddr,
				Qtype: dns.TypeA,
			},
		)...)

		return append(ir, zr.Records(
			dns.Question{
				Name:  zr.iAddr,
				Qtype: dns.TypeAAAA,
			},
		)...)
	case dns.TypeTXT:
		return []dns.RR{
			&dns.TXT{
				Hdr: dns.RR_Header{
					Name:   q.Name,
					Rrtype: dns.TypeTXT,
					Class:  dns.ClassINET,
					Ttl:    config.DefaultTTL,
				},
			},
		}
	default:
		return nil
	}
}

func (zr *ZoneRecord) sEnum(q dns.Question) []dns.RR {
	switch q.Qtype {
	case dns.TypeANY, dns.TypePTR:
		return []dns.RR{
			&dns.PTR{
				Hdr: dns.RR_Header{
					Name:   q.Name,
					Rrtype: dns.TypePTR,
					Class:  dns.ClassINET,
					Ttl:    config.DefaultTTL,
				},
				Ptr: zr.sAddr,
			},
		}
	default:
		return nil
	}
}