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A library for implementing an OAuth2 Server in php

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README.md

oauth2-server-php

Build Status

A library for implementing an OAuth2 Server in php

View the Full Working Demo! (code)

Autoloading

This library follows the zend PSR-0 standards. A number of autoloaders exist which can autoload this library for that reason, but if you are not using one, you can register the OAuth2_Autoloader:

require_once('/path/to/oauth2-server-php/src/OAuth2/Autoloader.php');
OAuth2_Autoloader::register();

If you use a package library like Composer, add the following to composer.json

{
    "require": {
        "bshaffer/oauth2-server-php": "v0.3",
        ...
    },
    ...
}

And then run composer.phar install

Checkout out the tag v0.3 will ensure your application doesn't break from backwards-compatibility issues, but also this means you will not receive the latest changes. To ride the bleeding edge of development, use dev-develop instead.

Get Started

Before getting started, take a look at the Oauth2 Demo Application and the source code for a concrete example of this library in action.

The quickest way to get started is to use the following code, plugging in your database information to the constructor of OAuth2_Storage_Pdo:

$storage = new OAuth2_Storage_Pdo(array('dsn' => $dsn, 'username' => $username, 'password' => $password));
$server = new OAuth2_Server($storage);
$server->addGrantType(new OAuth2_GrantType_UserCredentials($storage)); // or some other grant type.  This is the simplest
$server->handleGrantRequest(OAuth2_Request::createFromGlobals())->send();

Let's break this down line by line. The first line is how the OAuth2 data is stored. There are several built in storage types, for your convenience. To use PDO Storage, instantiate the OAuth2_Storage_Pdo class and provide the database connection arguments:

$storage = new OAuth2_Storage_Pdo(array('dsn' => $dsn, 'username' => $username, 'password' => $password));
$server = new OAuth2_Server($storage);

The next step is to add a grant type. This example uses the "User Credentials" grant type, which grants a token based on explicit user credentials passed to the request. Read more on supported grant types below, or in the OAuth2 spec. Each grant type also requires storage, so pass the existing storage to the constructor:

$server->addGrantType(new OAuth2_GrantType_UserCredentials($storage));

Call the grantAccessToken method to validate the request for the user credentials grant type. This will return the token if successful. Access the server's response object to send the successful response back, or the error response if applicable:

$server->handleGrantRequest(OAuth2_Request::createFromGlobals())->send();

This creates the OAuth2_Request object from PHP global variables (most common, you can override this if need be) and sends it to the server for assessment. The response by default is in json format, and includes the access token if successful, and error codes if not.

Server Methods

...an end-user (resource owner) can grant a printing service (client) access to her protected photos stored at a photo sharing service (resource server), without sharing her username and password with the printing service. Instead, she authenticates directly with a server trusted by the photo sharing service (authorization server), which issues the printing service delegation- specific credentials (access token).

~ OAuth2 (draft #31)

Most OAuth2 APIs will have endpoints for Authorize Requests, Grant Requests, and Access Requests:

  • Authorize Requests - An endpoint requiring the user to authenticate, which redirects back to the client with an authorization code
  • Grant Requests - An endpoint which the client uses to exchange the authorization code for an access token
  • Access Requests - Any API method requiring oauth2 authentication. The server will validate the incomming request, and then allow the application to serve back the protected resource

For these tyes of requests, this library provides the following methods:

Authorize Requests

handleAuthorizeRequest

  • Receives a request object for an authorize request, returns a response object with the appropriate response

validateAuthorizeRequest

  • Receives a request object, returns a Boolean for whether the incoming request is a valid Authorize Request. Applications should call this before displaying a login or authorization form to the user

Grant Requests

grantAccessToken

  • Receives a request object for a grant request, returns a token if the request is valid.

handleGrantRequest

  • Receives a request object for a grant request, returns a response object for the appropriate response.

getClientCredentials

  • parses the client credentials from the request and determines if they are valid

Access Requests

verifyAccessRequest

  • Receives a request object for an access request, finds the token if it exists, and returns a Boolean for whether the incomming request is valid

getAccessTokenData

  • Takes a token string as an argument and returns the token data if applicable, or null if the token is invalid

The Response Object

The response object serves the purpose of making your server OAuth2 compliant. It will set the appropriate status codes, headers, and response body for a valid or invalid oauth request. To use it as it's simplest level, just send the output and exit:

// will set headers, status code, and json response appropriately for success or failure
$server->grantAccessToken();
$server->getResponse()->send();

The response object can also be used to customize output. Below, if the request is NOT valid, the error is sent to the browser:

if (!$token = $server->grantAccessToken()) {
    $server->getResponse()->send();
    die();
}
echo sprintf('Your token is %s!!', $token);

This will populate the appropriate error headers, and return a json error response. If you do not want to send a JSON response, the response object can be used to display the information in any other format:

if (!$token = $server->grantAccessToken()) {
    $response = $server->getResponse();
    $parameters = $response->getParameters();
    // format as XML
    header("HTTP/1.1 " . $response->getStatusCode());
    header("Content-Type: text/xml");
    echo "<error><name>".$parameters['error']."</name><message>".$parameters['error_description']."</message></error>";
}

This is very useful when working in a framework or existing codebase, where this library will not have full control of the response.

Grant Types

There are many supported grant types in the OAuth2 specification, and this library allows for the addition of custom grant types as well. Supported grant types are as follows:

  1. Authorization Code

    An authorization code obtained by user authorization is exchanged for a token
    
  2. Implicit

    As part of user authorization, a token is retured to the client instead of an authorization code
    
  3. Resource Owner Password Credentials

    The username and password are submitted as part of the request, and a token is issued upon successful authentication
    
  4. Client Credentials

    The client can use their credentials to retrieve an access token directly, which will allow access to resources under the client's control
    
  5. JWT Authorization Grant

    The client can submit a JWT (JSON Web Token) in a request to the token endpoint. An access token (without a refresh token) is then returned directly.
    

Create a custom grant type by implementing the OAuth2_GrantTypeInterface and adding it to the OAuth2 Server object.

Scope

Configure your Scope

The use of Scope in an OAuth2 application is often key to proper permissioning. Scope is used to limit the authorization granted to the client by the resource owner. The most popular use of this is Facebook's ability for users to authorize a variety of different functions to the client ("access basic information", "post on wall", etc).

In this library, scope is handled by implementing OAuth2_Storage_ScopeInterface. This can be done using your own implementation, or by taking advantage of the existing OAuth2_Storage_Memory class:

// configure your available scopes
$defaultScope = 'basic';
$supportedScopes = array(
  'basic',
  'postonwall',
  'accessphonenumber'
);
$memory = new OAuth2_Storage_Memory(array(
  'default_scope' => $defaultScope,
  'supported_scopes => $supportedScoes'
));
$scopeUtil = new OAuth2_Scope($memory);

$server->setScopeUtil($scopeUtil);

This is the simplest way, but scope can by dynamically configured as well:

// configure your available scopes
$doctrine = Doctrine_Core::getTable('OAuth2Scope');
$scopeUtil = new OAuth2_Scope($doctrine);

$server->setScopeUtil($scopeUtil);

This example assumes the class being used implements OAuth2_Storage_ScopeInterface:

class OAuth2ScopeTable extends Doctrine_Table implements OAuth2_Storage_ScopeInterface
{
  public function getDefaultScope()
  {
    //...
  }

  public function getSupportedScopes($client_id = null)
  {
    //...
  }
}

Validate your scope

Configuring your scope in the server class will ensure requested scopes by the client are valid. However, there are two steps required to ensure the proper validation of your scope. First, the requested scope must be exposed to the resource owner upon authorization. In this library, this is left 100% to the implementation. The UI or whathaveyou must make clear the scope of the authorization being granted. Second, the resource request itself must specify what scope is required to access it:

// https://api.example.com/resource-requiring-postonwall-scope
$request = OAuth2_Request::createFromGlobals();
$scopeRequired = 'postonwall'; // this resource requires "postonwall" scope
if (!$server->verifyAccessRequest($request, $scopeRequired)) {
  // if the scope required is different from what the token allows, this will send a "401 insufficient_scope" error
  $server->getRequest()->send();
}

Customizing your scope

As the implementation of "scope" can be significantly different for each application, providing a different class other than OAuth2_Scope can be beneficial. Implement OAuth2_ScopeInterface in a custom class to fully customize.

Acknowledgements

This library is largely inspired and modified from Quizlet's OAuth2 PHP library

Contact

The best way to get help and ask questions is to file an issue. This will help answer questions for others as well.

If for whatever reason filing an issue does not make sense, contact Brent Shaffer (bshafs gmail com)

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