Original post is here.

You already know that OAuth 2.0 protocol is used for authentication and authorization. Laravel has Passport, which is a full Oauth 2.0 server implementation, used for authentication over API. By default, Laravel Passport has 4 types of Grants.

• Authorization Code
• Implicit
• Password
• Client Credentials

But unfortunately, for project purposes, we may need custom grants. I had to make a custom grant in my last project. In that project, users can log in through OTP. I did not find any solutions on Google. So, I jumped to solve the problem on my own. Through this post, I am going to show you how can you make a custom grant in your project in a very simple way.

Installation

In your laravel project root directory, open terminal and run

composer require laravel/passport

Passport needs database tables to save client tokens and related information.

php artisan migrate

To generate secure access tokens run,

php artisan passport:install

Add the Laravel\Passport\HasApiTokens trait to your App\User model. And use it.

use HasApiTokens, Notifiable;

Update the config/auth.php as below,

'api' => [
        'driver' => 'passport',
        'provider' => 'users',
 ],

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Custom OTPGrant

In AuthServiceProvider, I add a method to create OTPGrant.

protected function makeOtpGrant() 
{
   $grant = new OtpGrant(
      $this->app->make(RefreshTokenRepository::class)
   );

   $grant->setRefreshTokenTTL(Passport::refreshTokensExpireIn());

   return $grant;
}

My boot function is like below,

public function boot()
{
    $this->registerPolicies();
        
    app(AuthorizationServer::class)->enableGrantType(
        $this->makeOtpGrant(), Passport::tokensExpireIn()
    );

    Passport::routes();
}

AuthServiceProvider.php

https://gist.github.com/mrron313/b342732ff3a48e7b9f892e85487e3c98#file-authserviceprovider-php

Now make a class for OTPGrant, in app/Auth/Grants folder. Our OTPGrant class is like below.

https://gist.github.com/mrron313/521752911fdf7ef89affa7524744d22d#file-otpgrant-php

In my case, there are multiple OTP verifiers which will verify the OTP. In the API request body, there will be a parameter called otp_verifier. OtpVerifierFactory class is responsible for creating OTPVerifier based on the otp_verifier parameter. otp_verifier is an optional field. If it is not provided in the request body, OtpVerifierFactory will create a verifier object of BL_INTERNAL. OtpException throws exception for invalid OTP.

API Request/Response Example

In response, the client will get Access Token.

We are done. Enjoy your hot new custom grant.