add some helper structs

auth/auth.go

@@ -4,3 +4,25 @@ package auth
 type Authenticator interface {
 	Authenticate(user, password string) bool
 }
+
+type authenticatorList struct {
+	authers []Authenticator
+}
+
+func AuthenticatorList(authers ...Authenticator) Authenticator {
+	return &authenticatorList{
+		authers: authers,
+	}
+}
+
+func (p *authenticatorList) Authenticate(user, password string) bool {
+	if len(p.authers) == 0 {
+		return true
+	}
+	for _, auther := range p.authers {
+		if auther != nil && auther.Authenticate(user, password) {
+			return true
+		}
+	}
+	return false
+}