lego/challenge/dns01/domain.go
2022-11-28 17:53:13 +00:00

25 lines
598 B
Go

package dns01
import (
"fmt"
"strings"
"github.com/miekg/dns"
)
// ExtractSubDomain extracts the subdomain part from a domain and a zone.
func ExtractSubDomain(domain, zone string) (string, error) {
canonDomain := dns.Fqdn(domain)
canonZone := dns.Fqdn(zone)
if canonDomain == canonZone {
return "", fmt.Errorf("no subdomain because the domain and the zone are identical: %s", canonDomain)
}
if !dns.IsSubDomain(canonZone, canonDomain) {
return "", fmt.Errorf("%s is not a subdomain of %s", canonDomain, canonZone)
}
return strings.TrimSuffix(canonDomain, "."+canonZone), nil
}