createAccessToken() - Not expiring or returning existing tokens about oauth2-server-php

[F21]

I just had a sticky beak at facebook's implementation and it looks like in their case, they will actually send you the existing token again if you request it again and the token is not expired.

[bshaffer]

This is a tricky one... I cannot find anything in the spec to address this. The closest reference to this I have found is here:

Refresh tokens are issued to the client by the authorization server and are
used to obtain a new access token when the current access token
becomes invalid or expires, or to obtain additional access tokens
with identical or narrower scope (access tokens may have a shorter
lifetime and fewer permissions than authorized by the resource
owner

This implies that multiple access tokens with "identical or narrower scope" can exist at the time time. Perhaps we should make this configurable, and return the existing token by default.

[ccazette]

@bshaffer Thanks for the answer.
Facebook's implementation returns your existing access token straight through redirects, but you're originally requesting against the /authorize endpoint. Meaning before returning the existing access token, you can check if its scope match the requested scope of the new authorize request.
If yes, return it. If no, go through the entire OAuth dance again, and generate a new token.

[F21]

@bshaffer: Yes, perhaps we can mimic FB's implementation. How would you suggest this be done? Just a parameter in the $config array in the constructor of the server?

[bshaffer]

@F21 yes, but more specifically the GrantController, as the Server class is nothing more than a convenience wrapper for the three Controllers (if that's confusing, I'm sorry. Not sure how to get around that one).

If the flag is set, we'd just want to perform a call to getAccessToken with the proper checks, and skip the creation. It should be pretty straightforward

[F21]

@bshaffer Would like to have a crack at this. What are your views on implementing this?

Looking at #122, we would implement a check to see if the token exists and return the old token in createAccessToken() in ResponseType\AccessToken. Is this still the case?

Should this behaviour be the default behaviour? Should there be a configuration flag to turn this on and off? I see that the Server class has some functionality to set/get configuration. However, this is not being passed to the TokenController at all.

Finally, I am thinking that we should have a "fuzzy parameter" with a default of say 20 seconds. If the token expires 20 seconds from now, we return a new token instead.