Discourse Single-Sign-On Helper for PHP

This is a small class to help with providing an SSO source for Discourse forums. It provides 3 helper functions for validating incoming requests, extracting nonce, and building the returning query string., _(*1)

For more information on the SSO settings in Discourse, visit https://meta.discourse.org/t/official-single-sign-on-for-discourse/13045, _(*2)

Original code from Johan Jatko: https://github.com/ArmedGuy/discourse_sso_php, _(*3)

Installation

The package is registered at Packagist as cviebrock/discourse-php and can be installed using composer:, _(*4)

composer require "cviebrock/discourse-php"

Usage

$sso = new Cviebrock\DiscoursePHP\SSOHelper();

// this should be the same in your code and in your Discourse settings:
$secret = 'super_secret_sso_key';
$sso->setSecret( $secret );

// load the payload passed in by Discourse
$payload = $_GET['sso'];
$signature = $_GET['sig'];

// validate the payload
if (!($sso->validatePayload($payload,$signature))) {
    // invaild, deny
    header("HTTP/1.1 403 Forbidden");
    echo("Bad SSO request");
    die();
}

$nonce = $sso->getNonce($payload);

// Insert your user authentication code here ...

// Required and must be unique to your application
$userId = '...';

// Required and must be consistent with your application
$userEmail = '...';

// Optional - if you don't set these, Discourse will generate suggestions
// based on the email address

$extraParameters = array(
    'username' => $userUsername,
    'name'     => $userFullName
);

// build query string and redirect back to the Discourse site
$query = $sso->getSignInString($nonce, $userId, $userEmail, $extraParameters);
header('Location: http://discourse.example.com/session/sso_login?' . $query);
exit(0);