Move config into separate package

config/type_ip.go

@@ -0,0 +1,45 @@
+package config
+
+import (
+	"fmt"
+	"net"
+)
+
+type TypeIP struct {
+	value net.IP
+}
+
+func (c *TypeIP) UnmarshalText(data []byte) error {
+	if len(data) == 0 {
+		return nil
+	}
+
+	ip := net.ParseIP(string(data))
+	if ip == nil {
+		return fmt.Errorf("incorrect ip address: %s", string(data))
+	}
+
+	c.value = ip
+
+	return nil
+}
+
+func (c *TypeIP) MarshalText() ([]byte, error) { // nolint: unparam
+	return []byte(c.String()), nil
+}
+
+func (c TypeIP) String() string {
+	if c.value == nil {
+		return ""
+	}
+
+	return c.value.String()
+}
+
+func (c TypeIP) Value(defaultValue net.IP) net.IP {
+	if c.value == nil {
+		return defaultValue
+	}
+
+	return c.value
+}