Add dns client

option/dns.go

@@ -0,0 +1,12 @@
+package option
+
+type DNSOptions struct {
+	Servers []DNSServerOptions `json:"servers,omitempty"`
+}
+
+type DNSServerOptions struct {
+	Tag             string `json:"tag,omitempty"`
+	Address         string `json:"address"`
+	Detour          string `json:"detour,omitempty"`
+	AddressResolver string `json:"address_resolver,omitempty"`
+}