Feature: custom dns ipv4/ipv6 dual stack

dns/iputil.go

@@ -0,0 +1,32 @@
+package dns
+
+import (
+	"errors"
+	"net"
+)
+
+var (
+	errIPNotFound = errors.New("ip not found")
+)
+
+// ResolveIP with a host, return ip
+func ResolveIP(host string) (net.IP, error) {
+	if DefaultResolver != nil {
+		if DefaultResolver.ipv6 {
+			return DefaultResolver.ResolveIP(host)
+		}
+		return DefaultResolver.ResolveIPv4(host)
+	}
+
+	ip := net.ParseIP(host)
+	if ip != nil {
+		return ip, nil
+	}
+
+	ipAddr, err := net.ResolveIPAddr("ip", host)
+	if err != nil {
+		return nil, err
+	}
+
+	return ipAddr.IP, nil
+}