add some helper structs

admission/admission.go

@@ -3,3 +3,22 @@ package admission
 type Admission interface {
 	Admit(addr string) bool
 }
+
+type admissionList struct {
+	admissions []Admission
+}
+
+func AdmissionList(admissions ...Admission) Admission {
+	return &admissionList{
+		admissions: admissions,
+	}
+}
+
+func (p *admissionList) Admit(addr string) bool {
+	for _, admission := range p.admissions {
+		if admission != nil && !admission.Admit(addr) {
+			return false
+		}
+	}
+	return true
+}