SALTI

Simple Authentication and Authorization Library for Thali IoT

A very simple PATH and VERB base filtering of requests. Since PouchDB and Express-PouchDB are REST oriented, their permission model is basicaly REST - ie. PUT, POST, etc. This library is intended to be utilized with Pre-Shared Key (PSK) support. See JxCore #PR813

In addition, this is a simple Express middleware library that gets added to the Express app. For our needs, it is being added to the Express-Pouch layer and provides simple authentication and authorization through a simplified JSON structure.

Setup and Configuration

By default, the module, if it doesn't find any pskIdentity on the req.connection object it will assume its basicaly anonymous and assign sometning called public'. Thus any ACL rules that havepublic` will apply to that.

For example (see more about the ACL format below) - public is show here - giving public access to the path /foo for verbs of GET and POST.

{
    "path": "/foo/",
    "roles": [{
        "role": "public",
        "verbs": ["GET", "POST"]
    }, {
        "role": "user",
        "verbs": ["GET", "PUT", "POST"]
    }]
}
 

PSK Identity

When running JxCore using the PSK support, on the server side, it's necessary to add a property to the reqquest.connection object - like so:

var server = tls.createServer(serverOptions, function (connection) {
  //the object provided is a 'connection'
  console.log('%s connected', connection.pskIdentity);
  //do something with this - implementation specific...
  serverResults.push(connection.pskIdentity + ' ' + (connection.authorized ? 'authorized' : 'not authorized'));
  
  if (connection.authorized){
    //here we lookup a 'role' which will match what's in the ACL json - 
    var roleLookup = getRole(connection.pskIdentity);
    connection.pskIdentity = roleLookup;
  };
  //blah
  connection.once('data', function (data) {
    //
  });
 
});
 

Configuration of the Express-PouchDB server

Run the npm install

This is an npm module and can be installed as follows:

npm install --save salti
 

This sets it up for use in a NodeJS app.

Putting the module in the Express app.

 
var express = require('express'),
  http = require('http'),
  PouchDB = require('pouchdb'),
  router = express.Router();
 
//this tells PouchDB to use a subdirectory in the root.
var pbsetup = PouchDB.defaults({ prefix: './db/' });
var pouchPort = normalizePort(process.env.PORT2 || '3001');
 
//here we're using the express-pouchdb configuration for a minimal server.
var opts = {
  mode: 'minimumForPouchDB'
}
 
//this load the library.. 
var acllib = require('salti');
 
//this loads the JSON - which is an example - you're JSON can come from anywhere but should match the json schema
var acl = require('./pouchdb');
 
//Norml middleware usage - this adds it to the ruter...
router.all('*', acllib(acl));
 
//this is the express-pouchdb app - 
var pouchApp = require('express-pouchdb')(pbsetup, opts);
 
router.use('/', pouchApp);
app.use('/', router);
 
app.listen(pouchPort);
 

JSON Schema

The ACL file follows this schema. You can use the site http://jeremydorn.com/json-editor/ to manage JSON based upon any schema.

Or, use this url to manage something based upon THIS schema. http://bit.ly/1Qs3l66.

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "id": "/",
  "type": "array",
  "items": {
    "id": "1",
    "type": "object",
    "properties": {
      "path": {
        "id": "path",
        "type": "string"
      },
      "roles": {
        "id": "roles",
        "type": "array",
        "items": {
          "id": "1",
          "type": "object",
          "properties": {
            "role": {
              "id": "role",
              "type": "string"
            },
            "verbs": {
              "id": "verbs",
              "type": "array",
              "items": {
                "id": "0",
                "type": "string"
              }
            }
          }
        }
      }
    }
  }
}
 

Example ACL Json

The following is an example of the JSON used for the ACL.

Note that it is a "module" that returns an Array of Objects.

Example single ACL

Each Object has a path, then a role that is a Array of role.verbs.

For example, below we have a single path that 'public' can issue GET', andusercan issueGETandPOST`.

    "path": "/foobar",
    "roles": [{
        "role": "public",
        "verbs": ["GET"]
    }, {
        "role": "user",
        "verbs": ["GET", "POST"]
    }]
}
 

Exmaple Module used in sample.

 
"use strict";
 
 
module.exports =  [{
    "path": "/foobar",
    "roles": [{
        "role": "public",
        "verbs": ["GET"]
    }, {
        "role": "user",
        "verbs": ["GET"]
    }]
}, {
    "path": "/foo/",
    "roles": [{
        "role": "public",
        "verbs": ["GET", "POST"]
    }, {
        "role": "user",
        "verbs": ["GET", "PUR", "POST"]
    }]
}, {
    "path": "/bar",
    "roles": [{
        "role": "public",
        "verbs": ["GET"]
    }, {
        "role": "user",
        "verbs": ["GET"]
    }]
}];