An authorization layer for connect and express applications inspired by Apache's Shiro project. Fork of express-authorization.
npm install express-authorizeA fork of express-authorization optimized for server-side authorization with a more succinct syntax, better documentation and more robust examples.
This module is an express/connect middleware module for enforcing an Apache Shiro inspired authorization system.
$ npm install express-authorize
js
var express = require('express')
var app = express()
var authorizer = require('express-authorize')// Initialize authorizer with default options
authorizer.options = {
/*
withSubject : withSubject,
withPermissions : withPermissions,
onDenied : onDenied
*/
}
app.get('/restricted', authorizer.isPermitted("restricted:view"), function(req, res) {
// Restricted content
...
})
`Documentation
$3
Permission - a statement that defines access to an explicit activity, behaviour or action.
Subject - usually a website user, assigned permissions to enable access to sets of activities, behaviours, or actions.
Claim - a collection of permissions that are assigned to a subject and compiled into a regular expression. The regular expression matches any permissions that are permitted by the subject (user), or permission list under consideration.
$3
To practically assign sets of permissions to subjects, __express-authorize__ supports a wildcard enabled permission statement syntax that closely follows the syntax used by Apache Shiro.
A collection of permissions assigned to a subject are compiled by the system into a regular expression referred to as a claim.
* Permission statements are composed of from parts delimited by colons
:`.
* Permission parts can contain lists delimited by commas `,`.
Wildcard `?` and ` can be used to match one or more characters within an expression part.
* Examples:| Expression | Description |
| ---------- | ----------- |
|
`'system:*'` | String - has all permissions for system. Works for a single permission statement only |
| `[ 'system:*', 'activity:create,update,delete' ]` | Array - has all permissions for system and create/update/delete permissions for activity |
| `'user:john,bill,eric:retrieve,update'` | Multi-level - has retrieve and update permissions for the john, bill and eric users |$3
Create a new authorizer:
`js
var authorizer = require('express-authorize')
`$3
Setting options at initialization sets the default for that authorizer. The following options are available:- _withSubject_ - A subject, usually a user, is expected to be represented by an object with a permissions property referring to either a single permission or an array of permissions. Defaults to req.user or req.session.user.
- _withPermissions_ - Permissions statements are strings that can be specified in parameter lists that may include arrays of composited permissions. Ignored if non-default subject is specified.
- _onDenied_ - Callback function for when permission is denied. Defaults to setting the res.status to 403 and passing next with a 'Permission denied' error.
All of these options can be set either through chained API calls for ad hoc overriding, or on the __Authorizer.options__ object to establish new defaults.
#### Setting the default subject
withSubject can be specified using an array, a function or an asynchronous function.
js
// Use any object that has a "permissions" parameter (array)
var user = {
username : 'thisismyusername'
permissions : [ 'account:view', 'payment:view' ]
}
authorizer.options.withSubject = user
// OR use a function that returns a valid subject
authorizer.options.withSubject = function(req, res) {
var user = {
username : 'thisismyusername'
permissions : [ 'account:view', 'payment:view' ]
}
return user
}
// OR use an asynchronous function that passes a valid subject to a callback function
authorizer.options.withSubject = function(req, res, done) {
var user = {
username : 'thisismyusername'
permissions : [ 'account:view', 'payment:view' ]
}
done(user)
}
`#### Setting the default permissions
withPermissions can be specified using a string (for a single permission statement), an array, a function or an asynchronous function.
js
// Use a string for a single permission
authorizer.options.withPermissions = 'account:view'
// OR use an array of permissions
authorizer.options.withPermissions = [ 'account:view', 'payment:view' ]
// OR use a function
authorizer.options.withPermissions = function(req, res) {
return [ 'account:view', 'payment:view' ]
}
// OR use an asynchronous function
authorizer.options.withPermissions = function(req, res, done) {
done([ 'account:view', 'payment:view' ])
}
`#### Setting the default onDenied callback
onDenied must be an express/connect compatible middleware function
js
authorizer.options.onDenied = function(req, res, next) {
res.redirect('/login')
}
`
$3
Options can be overridden in an ad hoc manner using a permission query.
In the permission query API, a permission source is placed under consideration and compiled into a claim that is
queried to confirm permitted permissions. This is beneficial when you want to change the considered subject, permissionsjs
// Use the default options
authorizer.isPermitted('express:coding')
// One-time override of the subject being considered
authorizer
.withSubject(user)
.isPermitted('express:coding')
// One-time override of the permissions being considered
authorizer
.withPermissions('source:edit', 'express:*')
.isPermitted('express:coding')
// One-time override of the onDenied function
authorizer
.onDenied(function(req, res, next) {
res.redirect('/login')
})
.isPermitted('express:coding')
`Methods can be chained in combination.
#### From subject or permission list -> claim -> isPermitted
js
authorizer.withSubject | authorizer.withPermissions -> claim
`
The __withSubject__ and __withPermissions__ methods are used to generate a claim object. Note that specifying a subject source always supercedes specifying a permission source. Only one consideration source should be used at a time.$3
__express-authorize__ uses a fluent API to generate express middleware for enforcing permissions.
js
app.get('/restricted', authorizer.isPermitted("restricted:view"), function(req, res) {
// Restricted content
...
})
`
To generate an express middleware, you write a call chain starting with a reference to __express-authorize__
and ending in a call to __isPermitted__. The call to __isPermitted__ returns a connect/express compliant middleware function.By default, __express-authorize__ sources permissions from the session through references to session.user.permissions or session.permissions.
To consider alternative permission sources, __withSubject__ or __withPermissions__ are used.
js
app.get('/restricted',
authorizer
.withPermissions(["identity:*"])
.onDenied(function(req, res, next) {
res.redirect('/login')
})
.isPermitted("identity:edit"),
function(req, res) {
// Restricted content
res.send('Hooray! You have permission to access this secret content!')
...
})`$3
By default, __express-authroize__ sources permissions using the following function:
js
function withPermissionsDefault(req, res) {
if (req.user && req.user.permissions) return req.user.permissions
if (req.session && req.session.user && req.session.user.permissions) return req.session.user.permissions
if (req.permissions) return req.permissions
return []
}
`The default onDenied function sets
res.status(403)` and passes an error to next.
`js
function onDeniedDefault(req, res, next) {
res.status(403)
next('Permission denied')
}
`$3
When calling require('express-authorize')` a new Authorizer instance is returned. In order to initialize a second instance do the following:
`js
var anotherAuthorizer = new authorizer.Authorizer(/ options /)
``MIT License
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