This modules buffers previous successful HTTP Responses for the OAuth 2.0 RefreshTokenGrant of the simple_oauth drupal contrib module.

Table of Contents

• Motivation
• How does it work?
• Installation
• Configuration
  • Enable / Disable
  • Buffer TTL
  • Wait Timeout
  • Wait Retry Count
• Module Development
  • Setup Dev Envirionment

Given the following scenario:

• User accesses a page of a web app
• Multiple requests are made to fetch some data
• Those requests detect an expired access token and try to refresh the tokens
• Multiple requests to refresh the tokens are made to Drupal
• Drupal handles the first token refresh successfully
• Other requests will fail, because the refresh token has been revoked on the first request

This scenario is a real pain to solve on the client. Therefore this module tries to solve this problem directly on the server.

This leads to e.g. 5 simultaneous token refresh requests to return the same response.

Whenever a token refresh request is made to /oauth/token with the payload format for the RefreshTokenGrant, this module first creates a unique ID for this request and checks if this exact request was already made previously.

• If it was not, the request is handled normally by the Authorization Server and the response is then temporarily saved.
• If it was, but the token refresh is not finished yet, the server waits for the refresh to complete and then returns the saved response.
• If it was and the refresh was already completed, it returns the previous response.

composer require drupal/simple_auth_refresh_token_buffer
drush en simple_auth_refresh_token_buffer

The functionality of this module can be configured per Consumer. Settings can therefore be found on the settings page for each Consumer.

For the refresh token buffer to take effect, the functionality must be explicitly enabled for the desired Consumer.

If enabled, refresh token responses are buffered for each request identified as the given Consumer.

The time to live for each buffered response can be configured as a Service Parameter:

parameters:
  # Make buffered responses expire after 60 seconds.
  simple_oauth_refresh_token_buffer.expire: 60

When a token refresh is already pending, the current request for the same token refresh must wait for a set period of time until checking again if the response for the token refresh has been buffered.

The timeout value can be configured in the Consumer settings.

Number of tries the request handler checks for the finished token refresh response when the token refresh is already pending.

After exceeding this retry count an error response is being returned.

The retry count value can be configured in the Consumer settings.

Development is done over at GitHub!

Please file any issues and pull requests there.

To work on the module itself, a development environment can be easily setup with the help of Nix.

Heavy lifting is done by the Drupal Spoons Composer-Plugin!

# Spawn a devshell
nix develop

# Setup dependencies
setup-drupal

# Run PHPCS
composer phpcs

# Run PHPUnit
composer unit