headscale/dns.go
2021-10-09 12:22:13 +02:00

45 lines
1.1 KiB
Go

package headscale
import (
"fmt"
"strings"
"inet.af/netaddr"
"tailscale.com/util/dnsname"
)
func generateMagicDNSRootDomains(ipPrefix netaddr.IPPrefix, baseDomain string) (*[]dnsname.FQDN, error) {
base, err := dnsname.ToFQDN(baseDomain)
if err != nil {
return nil, err
}
// TODO(juanfont): we are not handing out IPv6 addresses yet
// and in fact this is Tailscale.com's range (not the fd7a:115c:a1e0: range in the fc00::/7 network)
ipv6base := dnsname.FQDN("0.e.1.a.c.5.1.1.a.7.d.f.ip6.arpa.")
fqdns := []dnsname.FQDN{base, ipv6base}
netRange := ipPrefix.IPNet()
maskBits, _ := netRange.Mask.Size()
lastByte := maskBits / 8
unmaskedBits := 8 - maskBits%8
min := uint(netRange.IP[lastByte])
max := uint((min + 1<<uint(unmaskedBits)) - 1)
rdnsSlice := []string{}
for i := lastByte - 1; i >= 0; i-- {
rdnsSlice = append(rdnsSlice, fmt.Sprintf("%d", netRange.IP[i]))
}
rdnsSlice = append(rdnsSlice, "in-addr.arpa.")
rdnsBase := strings.Join(rdnsSlice, ".")
for i := min; i <= max; i++ {
fqdn, err := dnsname.ToFQDN(fmt.Sprintf("%d.%s", i, rdnsBase))
if err != nil {
continue
}
fqdns = append(fqdns, fqdn)
}
return &fqdns, nil
}