verifyAndParseCodeFromCallbackUri function

String verifyAndParseCodeFromCallbackUri(String callbackUri, String redirectUri, String state)

A utility function to verify and parse the code from the authorization callback URI.

• verify the callback URI
• verify the state
• error detection
• parse the code from the callback URI

Implementation

String verifyAndParseCodeFromCallbackUri(
  String callbackUri,
  String redirectUri,
  String state,
) {
  if (!callbackUri.startsWith(redirectUri)) {
    throw LogtoAuthException(
      LogtoAuthExceptions.callbackUriValidationError,
      'invalid redirect uri',
    );
  }

  var queryParams = Uri.parse(callbackUri).queryParameters;

  if (queryParams['error'] != null) {
    throw LogtoAuthException(
      LogtoAuthExceptions.callbackUriValidationError,
      queryParams['error']!,
      queryParams['error_description'],
    );
  }

  if (queryParams['state'] == null) {
    throw LogtoAuthException(
      LogtoAuthExceptions.callbackUriValidationError,
      'missing state',
    );
  }

  if (queryParams['state'] != state) {
    throw LogtoAuthException(
      LogtoAuthExceptions.callbackUriValidationError,
      'invalid state',
    );
  }

  if (queryParams['code'] == null) {
    throw LogtoAuthException(
      LogtoAuthExceptions.callbackUriValidationError,
      'missing code',
    );
  }

  return queryParams['code']!;
}