While Dwolla doesn't support a state
parameter, as an alternative, you can specify the state
parameter as a querystring variable in the return_uri
.
For example, if you used this return URI:
http://www.example.com/somepage?state=foobar
After granting permissions to your application on Dwolla, the user will be redirected to your application via:
http://www.example.com/somepage?state=foobar&code={OAuth Verification Code}