token_from required for oauth2_introspection but ignores "seperated" values

[pike1212]

Describe the bug

The token_from field in oauth2_introspection appears to be required now, which is fine, but when I specify "Authorization" it no longer splits up the token field if the value is "Bearer token" in the BearerTokenFromRequest method.

[aeneasr]

I'm not sure I understand the issue?

[pike1212]

If my config looks like

      token_from:
        header: Authorization

And the header is Authroization: Bearer 12345

Then oathkeeper will try to introspect Bearer 12345 instead of just 12345

https://github.com/ory/oathkeeper/blob/master/helper/bearer.go#L38

[aeneasr]

To use the Authorization header you should levae token_from empty. But I do understand that this is confusing, and that this should work properly. We should probably check here ( https://github.com/ory/oathkeeper/blob/master/helper/bearer.go#L40 ) if the value is Authorization or not and if it is, just skip the if and go to: https://github.com/ory/oathkeeper/blob/master/helper/bearer.go#L52

Would you be open for a PR?