Doorkeeper - limit grant types on specific endpoint

Question

I have a grape API that provides some endpoints, and doorkeeper to handle authorization. By default, doorkeeper enable authorization code grant as well as client credentials grant. So I can request an access token only with those two grants.

I wonder if there is a way in doorkeeper to limit or at least get the grant type used to request a provided access token?

For example, if someone request a token with the authorization code grant, when he is requesting a resource on the API, I want to know that he used the authorization code grant to get his token. I can then check for every request made if the given token is made from an authorization code grant or not and provide the resource or not.

I know there is application's scopes to handle specific authorization, but I wanted to know if there is a solution to this problem. This might not be a legit problem, I might be missing something from the OAuth specification, so all comments are welcome!

Answer 1

Access tokens issued by Client Credentials flow are not associated with any resource owner. So, in your use case, you can tell whether an access token has been issued by Authorization Code flow or Client Credentials flow by checking whether the access token is associated with a resource owner or not.