def _do_token_refresh(self, request):
# type: (Mapping[str, str]) -> oic.oic.message.AccessTokenResponse
"""
Handles a token request for refreshing an access token (grant_type=refresh_token).
:param request: parsed http request parameters
:return: a token response containing a new Access Token and possibly a new Refresh Token
:raise InvalidTokenRequest: if the token request is invalid
"""
token_request = RefreshAccessTokenRequest().from_dict(request)
try:
token_request.verify()
except MessageException as e:
raise InvalidTokenRequest(str(e), token_request) from e
response = AccessTokenResponse()
access_token, refresh_token = self.authz_state.use_refresh_token(
token_request['refresh_token'], scope=token_request.get('scope'))
self._add_access_token_to_response(response, access_token)
if refresh_token:
response['refresh_token'] = refresh_token
return response
