npm package: @singcl/acl
Description: An Access Control List module, based on Redis with Express middleware support
Author: Manuel Astudillo
Latest version: 0.4.12

# NODE ACL - Access Control Lists for Node

This module provides a minimalistic ACL implementation inspired by Zend_ACL.

When you develop a web site or application you will soon notice that sessions are not enough to protect all the
available resources. Avoiding that malicious users access other users content proves a much more
complicated task than anticipated. ACL can solve this problem in a flexible and elegant way.

Create roles and assign roles to users. Sometimes it may even be useful to create one role per user,
to get the finest granularity possible, while in other situations you will give the *asterisk* permission
for admin kind of functionality.

A Redis, MongoDB and In-Memory based backends are provided built-in in the module. There are other third party backends such as [*knex*](https://github.com/christophertrudel/node_acl_knex) based, [*firebase*](https://github.com/tonila/node_acl_firebase) and [*elasticsearch*](https://github.com/adnanesaghir/acl-elasticsearch-backend). There is also an alternative memory backend that supports [*regexps*](https://github.com/futurechan/node_acl-mem-regexp).

Follow [manast](http://twitter.com/manast) for news and updates regarding this library.

## Status

[![BuildStatus](https://secure.travis-ci.org/OptimalBits/node_acl.png?branch=master)](http://travis-ci.org/OptimalBits/node_acl)
[![Dependency Status](https://david-dm.org/OptimalBits/node_acl.svg)](https://david-dm.org/OptimalBits/node_acl)
[![devDependency Status](https://david-dm.org/OptimalBits/node_acl/dev-status.svg)](https://david-dm.org/OptimalBits/node_acl#info=devDependencies)

## Features

- Users
- Roles
- Hierarchies
- Resources
- Express middleware for protecting resources.
- Robust implementation with good unit test coverage.

## Installation

Using npm:

```javascript
npm install acl
```

## Documentation

* [addUserRoles](#addUserRoles)
* [removeUserRoles](#removeUserRoles)
* [userRoles](#userRoles)
* [roleUsers](#roleUsers)
* [hasRole](#hasRole)
* [addRoleParents](#addRoleParents)
* [removeRoleParents](#removeRoleParents)
* [removeRole](#removeRole)
* [removeResource](#removeResource)
* [allow](#allow)
* [removeAllow](#removeAllow)
* [allowedPermissions](#allowedPermissions)
* [isAllowed](#isAllowed)
* [areAnyRolesAllowed](#areAnyRolesAllowed)
* [whatResources](#whatResources)
* [middleware](#middleware)
* [backend](#backend)

## Examples

Create your acl module by requiring it and instantiating it with a valid backend instance:

```javascript
var acl = require('acl');

// Using redis backend
acl = new acl(new acl.redisBackend(redisClient, prefix));

// Or Using the memory backend
acl = new acl(new acl.memoryBackend());

// Or Using the mongodb backend
acl = new acl(new acl.mongodbBackend(dbInstance, prefix));
```

All the following functions return a promise or optionally take a callback with
an err parameter as last parameter. We omit them in the examples for simplicity.

Create roles implicitly by giving them permissions:

```javascript
// guest is allowed to view blogs
acl.allow('guest', 'blogs', 'view')

// allow function accepts arrays as any parameter
acl.allow('member', 'blogs', ['edit', 'view', 'delete'])
```

Users are likewise created implicitly by assigning them roles:

```javascript
acl.addUserRoles('joed', 'guest')
```

Hierarchies of roles can be created by assigning parents to roles:

```javascript
acl.addRoleParents('baz', ['foo', 'bar'])
```

Note that the order in which you call all the functions is irrelevant (you can add parents first and assign permissions to roles later)

```javascript
acl.allow('foo', ['blogs', 'forums', 'news'], ['view', 'delete'])
```

Use the wildcard to give all permissions:

```javascript
acl.allow('admin', ['blogs', 'forums'], '*')
```

Sometimes is necessary to set permissions on many different roles and resources. This would
lead to unnecessary nested callbacks for handling errors. Instead use the following:

```javascript
acl.allow([
    {
        roles:['guest', 'member'],
        allows:[
            {resources:'blogs', permissions:'get'},
            {resources:['forums', 'news'], permissions:['get', 'put', 'delete']}
        ]
    },
    {
        roles:['gold', 'silver'],
        allows:[
            {resources:'cash', permissions:['sell', 'exchange']},
            {resources:['account', 'deposit'], permissions:['put', 'delete']}
        ]
    }
])
```

You can check if a user has permissions to access a given resource with *isAllowed*:

```javascript
acl.isAllowed('joed', 'blogs', 'view', function(err, res){
    if(res){
        console.log("User joed is allowed to view blogs")
    }
})
```


Of course arrays are also accepted in this function:

```javascript
acl.isAllowed('jsmith', 'blogs', ['edit', 'view', 'delete'])
```

Note that all permissions must be fulfilled in order to get *true*.


Sometimes is necessary to know what permissions a given user has over certain resources:

```javascript
acl.allowedPermissions('james', ['blogs', 'forums'], function(err, permissions){
    console.log(permissions)
})
```

It will return an array of resource:[permissions] like this:

```javascript
[{'blogs' : ['get', 'delete']},
 {'forums':['get', 'put']}]
```


Finally, we provide a middleware for Express for easy protection of resources.

```javascript
acl.middleware()
```

We can protect a resource like this:

```javascript
app.put('/blogs/:id', acl.middleware(), function(req, res, next){…}
```

The middleware will protect the resource named by *req.url*, pick the user from *req.session.userId* and check the permission for *req.method*, so the above would be equivalent to something like this:

```javascript
acl.isAllowed(req.session.userId, '/blogs/12345', 'put')
```

The middleware accepts 3 optional arguments, that are useful in some situations. For example, sometimes we
cannot consider the whole url as the resource:

```javascript
app.put('/blogs/:id/comments/:commentId', acl.middleware(3), function(req, res, next){…}
```

In this case the resource will be just the three first components of the url (without the ending slash).

It is also possible to add a custom userId or check for other permissions than the method:

```javascript
app.put('/blogs/:id/comments/:commentId', acl.middleware(3, 'joed', 'post'), function(req, res, next){…}
```

## Methods

<a name="addUserRoles"/>

### addUserRoles( userId, roles, function(err) )

Adds roles to a given user id.

__Arguments__

```javascript
    userId   {String|Number} User id.
    roles    {String|Array} Role(s) to add to the user id.
    callback {Function} Callback called when finished.
```

---------------------------------------

<a name="removeUserRoles"/>

### removeUserRoles( userId, roles, function(err) )

Remove roles from a given user.

__Arguments__

```javascript
    userId   {String|Number} User id.
    roles    {String|Array} Role(s) to remove to the user id.
    callback {Function} Callback called when finished.
```

---------------------------------------

<a name="userRoles" />

### userRoles( userId, function(err, roles) )

Return all the roles from a given user.

__Arguments__

```javascript
    userId   {String|Number} User id.
    callback {Function} Callback called when finished.
```

---------------------------------------

<a name="roleUsers" />

### roleUsers( rolename, function(err, users) )

Return all users who has a given role.

__Arguments__

```javascript
    rolename   {String|Number} User id.
    callback {Function} Callback called when finished.
```

---------------------------------------

<a name="hasRole" />

### hasRole( userId, rolename, function(err, hasRole) )

Return boolean whether user has the role

__Arguments__

```javascript
    userId   {String|Number} User id.
    rolename {String|Number} role name.
    callback {Function} Callback called when finished.
```

---------------------------------------

<a name="addRoleParents" />

### addRoleParents( role, parents, function(err) )

Adds a parent or parent list to role.

__Arguments__

```javascript
    role     {String} Child role.
    parents  {String|Array} Parent role(s) to be added.
    callback {Function} Callback called when finished.
```

---------------------------------------

<a name="removeRoleParents" />

### removeRoleParents( role, parents, function(err) )

Removes a parent or parent list from role.

If `parents` is not specified, removes all parents.

__Arguments__

```javascript
    role     {String} Child role.
    parents  {String|Array} Parent role(s) to be removed [optional].
    callback {Function} Callback called when finished [optional].
```

---------------------------------------

<a name="removeRole" />

### removeRole( role, function(err) )

Removes a role from the system.

__Arguments__

```javascript
    role     {String} Role to be removed
    callback {Function} Callback called when finished.
```

---------------------------------------

<a name="removeResource" />
### removeResource( resource, function(err) )

Removes a resource from the system

__Arguments__

```javascript
    resource {String} Resource to be removed
    callback {Function} Callback called when finished.
```

---------------------------------------

<a name="allow" />

### allow( roles, resources, permissions, function(err) )

Adds the given permissions to the given roles over the given resources.

__Arguments__

```javascript
    roles       {String|Array} role(s) to add permissions to.
    resources   {String|Array} resource(s) to add permisisons to.
    permissions {String|Array} permission(s) to add to the roles over the resources.
    callback    {Function} Callback called when finished.
```

### allow( permissionsArray, function(err) )

__Arguments__

```javascript
    permissionsArray {Array} Array with objects expressing what permissions to give.
       [{roles:{String|Array}, allows:[{resources:{String|Array}, permissions:{String|Array}]]

    callback         {Function} Callback called when finished.
```

---------------------------------------

<a name="removeAllow" />

###  removeAllow( role, resources, permissions, function(err) )

Remove permissions from the given roles owned by the given role.

Note: we loose atomicity when removing empty role_resources.

__Arguments__

```javascript
    role        {String}
    resources   {String|Array}
    permissions {String|Array}
    callback    {Function}
```

---------------------------------------

<a name="allowedPermissions" />

### allowedPermissions( userId, resources, function(err, obj) )

Returns all the allowable permissions a given user have to
access the given resources.

It returns an array of objects where every object maps a
resource name to a list of permissions for that resource.

__Arguments__

```javascript
    userId    {String|Number} User id.
    resources {String|Array} resource(s) to ask permissions for.
    callback  {Function} Callback called when finished.
```

---------------------------------------

<a name="isAllowed" />

### isAllowed( userId, resource, permissions, function(err, allowed) )

Checks if the given user is allowed to access the resource for the given
permissions (note: it must fulfill all the permissions).

__Arguments__

```javascript
    userId      {String|Number} User id.
    resource    {String} resource to ask permissions for.
    permissions {String|Array} asked permissions.
    callback    {Function} Callback called with the result.
```

---------------------------------------
<a name="areAnyRolesAllowed" />

### areAnyRolesAllowed( roles, resource, permissions, function(err, allowed) )

Returns true if any of the given roles have the right permissions.

__Arguments__

```javascript
    roles       {String|Array} Role(s) to check the permissions for.
    resource    {String} resource to ask permissions for.
    permissions {String|Array} asked permissions.
    callback    {Function} Callback called with the result.
```

---------------------------------------
<a name="whatResources" />

### whatResources(role, function(err, {resourceName: [permissions]})

Returns what resources a given role has permissions over.

__Arguments__

```javascript
    role        {String|Array} Roles
    callback    {Function} Callback called with the result.
```

whatResources(role, permissions, function(err, resources) )

Returns what resources a role has the given permissions over.

__Arguments__

```javascript
    role        {String|Array} Roles
    permissions {String|Array} Permissions
    callback    {Function} Callback called with the result.
```

---------------------------------------

<a name="middleware" />

### middleware( [numPathComponents, userId, permissions] )

Middleware for express.

To create a custom getter for userId, pass a function(req, res) which returns the userId when called (must not be async).

__Arguments__

```javascript
    numPathComponents {Number} number of components in the url to be considered part of the resource name.
    userId            {String|Number|Function} the user id for the acl system (defaults to req.session.userId)
    permissions       {String|Array} the permission(s) to check for (defaults to req.method.toLowerCase())
```

---------------------------------------

<a name="backend" />

### backend( db, [prefix] )

Creates a backend instance. All backends except Memory require driver or database instance. `useSingle` is only applicable to the MongoDB backend.

__Arguments__

```javascript
    db        {Object} Database instance
    prefix    {String} Optional collection prefix
    useSingle     {Boolean} Create one collection for all resources (defaults to false)
```

```javascript
var mongodb = require('mongodb');
mongodb.connect("mongodb://127.0.0.1:27017/acltest", function(error, db) {
  var mongoBackend = new acl.mongodbBackend(db, 'acl_');
});
```

Creates a new MongoDB backend using database instance `db`.

```javascript
var client = require('redis').createClient(6379, '127.0.0.1', {no_ready_check: true});
var redisBackend = new acl.redisBackend(client);
```

Creates a new Redis backend using Redis client `client`.

## Tests

Run tests with `npm` (requires mocha):
```javascript
 npm test
```

## Future work

- Support for denials (deny a role a given permission)


## License

(The MIT License)

Copyright (c) 2011-2013 Manuel Astudillo <manuel@optimalbits.com>

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.