Added function to check group permission.

nodejs/utils/permission.js

@@ -0,0 +1,22 @@
+'use static';
+
+const {Group} = require('../models/group_ldap');
+
+let byGroup = async function(user, groups){
+	for(let group of groups){
+		try{
+			group = await Group.get(group);
+			if(group.member.includes(user.dn)) return true
+		}catch(error){
+			throw error;
+		}
+
+		let error = new Error('Insufficient Permission');
+		error.name = 'Insufficient Permission';
+		error.message = `You do not have permission to perform this action.`;
+		error.status = 401;
+		throw error;
+	}
+}
+
+module.exports = {byGroup};