passport-strategy

An abstract class implementing Passport's strategy API.

Install

$ npm install passport-strategy

Usage

This module exports an abstract Strategy class that is intended to be subclassed when implementing concrete authentication strategies. Once implemented, such strategies can be used by applications that utilize Passport middleware for authentication.

Subclass Strategy

Create a new CustomStrategy constructor which inherits from Strategy:

var util = require('util')
  , Strategy = require('passport-strategy');

function CustomStrategy(...) {
  Strategy.call(this);
}

util.inherits(CustomStrategy, Strategy);

Set instance attributes

Passport will identify mounted strategies by the instance's name attribute, so be sure to set one in the constructor:

var util = require('util')
  , Strategy = require('passport-strategy');

function CustomStrategy(...) {
  Strategy.call(this);

  this.name = 'custom'; // set instance name
}

util.inherits(CustomStrategy, Strategy);

Later, when a user calls passport.authenticate to acquire the authentication middleware that employs this strategy, the value of this name attribute is what must be passed in as the first argument:

var authMiddleware = passport.authenticate('custom');

Implement Authentication

Implement the authenticate method, performing the necessary operations required by the authentication scheme or protocol being implemented.

CustomStrategy.prototype.authenticate = function(req, options) {
  // TODO: authenticate request
}

Upon mounting a strategy instance on passport, it will be augmented with several methods. These methods are essential to writing a working authenticate method:

• error(err), indicates to passport that an error occurred in authenticating the request.
• fail(options, statusCode), indicates to passport that the request failed authentication.
• success(userObj), indicates to passport that the request was successfully authenticated and provides the user object with which to associate the new authenticated session.

Since the strategy instance is augmented with these methods, they can be accessed as properties of this within the authenticate method.

Examples

AlwaysSucceedStrategy.prototype.authenticate = function(req, options) {
    this.success({
        username : 'bogus',
        userId : NaN
    });
}

AlwaysFailStrategy.prototype.authenticate = function(req, options) {
    this.fail({
        message : "working as intended"
    }, 200);
}

AlwaysErrorStrategy.prototype.authenticate = function(req, options) {
    var err = new Error("Strategy: working as intended")
    this.error(err);
}

CoinFlipStrategy.prototype.authenticate = function(req, options) {
    if(Math.random() < 0.5) {
        this.success({
            username : "George Washington",
            userId : 25
        });
    } else {
        this.fail();
    }
}

Related Modules

• chai-passport-strategy — helpers for testing strategies with the Chai assertion library

Tests

$ npm install
$ npm test

Credits

• Jared Hanson

License

The MIT License

Copyright (c) 2011-2014 Jared Hanson <http://jaredhanson.net/>