Guard Dog -v1.0.0

npm install guarddog [https://www.npmjs.com/package/guarddog][8]

A middleware mainly for expressjs to validate and filter out unwanted API requests and, to define an expected schema with data types for JSON objects.

Architecture

Node.JS APIs are mostly designed to receive http requests with JSON objects. Almost always there is an expected object schema for that particular API.

Note:

• Even though the API is secured using a tokening mechanism , attacker can obtain a token , he can inject the server code with unnecessary API requests .
• Attacker can do minor changes to JSON payloads and attack directly in to your code and it may give valid results from the backend.
• Running unexpected objects all over the application can cause unhandled exceptions and in unexpected places

Example

Expected object :- { credentials: { username: "John" , password :"1234"}}

Actual Object { cred: { username: "John" , password :"1234"}}

var username = object.credentials.username ; This code will return an error saying, cannot read property username of null.

How to use

1. Install the NPM package Guarddog

You can install the npm using following command in your project,

[npm install --save guarddog][8]

As a prerequisite ,a body parser has to be used. If you haven't any, you can install by npm install --save body-parser

2. Require Guarddog in your project

var bodyParser = require('body-parser'); var guardDog=require('guarddog');

3. Define a strategy for Guarddog

guardDog.setStratergyJson(stratergyJson);

stratergyJson should have 2 major properties.

• apis : expected api schema
• onFail: fail event ( this function will be called in case of a mismatch)

Sample object :

var stratergyJson={

onFail:function(msg){
    console.log("Failure : ",msg)
},
apis:{
    "/user/token":{
        POST:{
            body:[{
                    "credentials":{
                        "username":"string",
                        "password":"string"
                    }
                },
                {
                    "details":{
                        "age":"number",
                        "address":"string",
                        "code":"number",
                        "hobbies":"array"
                    }
                }

            ],
          

        }
    }
}

};

Here in this explanation , multiple body schemes are passed to body property of the "/user/token" api. Such scenarios you can use an object array to define multiple objects.

Data types: Datatype should be given as values for the leaf nodes of json object. In above example, username is an string , age is a number and hobbies is an array. list of supporting data types are

• string
• number
• array

Method types: currently Guarddog supports below methods only

• GET
• POST
• PUT
• DELETE
• PATCH

3. Put the guarddog to guard

Here as a prerequisite ,stratergy should be set and the request should be parsed by a body parser as a must before it reaches the guarddog middleware . (since guarddog expects a body property in the request)

guardDog.setStratergyJson(stratergyJson);

app.use(bodyParser.json()); app.user(guardDog.guard)

Please feel free to point out issues in [github issues of guarddog][7] . Gurddog 2.0.0 is under development and will be released soon. Author

Don Rajitha Dissanayake [email protected] [7]:https://github.com/rajithadon/guarddog/issues [8]: https://www.npmjs.com/package/guarddog