1 files changed, 44 insertions, 0 deletions
diff --git a/core/dnsserver/address.go b/core/dnsserver/address.go
new file mode 100644
index 000000000..865d082cc
--- /dev/null
+++ b/core/dnsserver/address.go
@@ -0,0 +1,44 @@
+package dnsserver
+
+import (
+	"fmt"
+	"net"
+	"strings"
+
+	"github.com/miekg/dns"
+)
+
+type zoneAddr struct {
+	Zone string
+	Port string
+}
+
+// String return z.Zone + ":" + z.Port as a string.
+func (z zoneAddr) String() string { return z.Zone + ":" + z.Port }
+
+// normalizeZone parses an zone string into a structured format with separate
+// host, and port portions, as well as the original input string.
+func normalizeZone(str string) (zoneAddr, error) {
+	var err error
+
+	// separate host and port
+	host, port, err := net.SplitHostPort(str)
+	if err != nil {
+		host, port, err = net.SplitHostPort(str + ":")
+		// no error check here; return err at end of function
+	}
+
+	if len(host) > 255 {
+		return zoneAddr{}, fmt.Errorf("specified zone is too long: %d > 255", len(host))
+	}
+	_, d := dns.IsDomainName(host)
+	if !d {
+		return zoneAddr{}, fmt.Errorf("zone is not a valid domain name: %s", host)
+	}
+
+	if port == "" {
+		port = "53"
+	}
+
+	return zoneAddr{Zone: strings.ToLower(dns.Fqdn(host)), Port: port}, err
+}