def get_authenticated_user(self, callback):
        request_key = self.request.args.get('oauth_token')
        oauth_verifier = self.request.args.get('oauth_verifier', None)
        request_cookie = self.request.cookies.get('_oauth_request_token')

        if request_cookie:
            parts = request_cookie.split('|')
            if len(parts) == 2:
                try:
                    cookie_key = base64.b64decode(parts[0])
                    cookie_secret = base64.b64decode(parts[1])
                except TypeError, e:
                    # TypeError: Incorrect padding
                    logging.exception(e)
                    request_cookie = None
            else:
                request_cookie = None

        if not request_cookie:
            return callback(None)

        self.session_store.delete_cookie('_oauth_request_token')

        if cookie_key != request_key:
            return callback(None)

        token = dict(key=cookie_key, secret=cookie_secret)
        if oauth_verifier:
            token['verifier'] = oauth_verifier

        try:
            url = self._oauth_access_token_url(token)
            response = urlfetch.fetch(url, deadline=10)
        except urlfetch.DownloadError, e:
            logging.exception(e)
            response = None

        return self._on_access_token(callback, response)
Gets the OAuth authorized user and access token on callback.
dataset/ETHPy150Open moraes/tipfy/tipfy/auth/oauth.py/OAuthMixin.get_authenticated_user