handle invalid B2 server errors

Author: mjurbanski-reef

b2sdk/b2http.py

@@ -423,7 +423,9 @@ def _translate_errors(cls, fcn, post_params=None):
  # Decode the error object returned by the service
  try:
  error = json.loads(response.content.decode('utf-8')) if response.content else {}
- except (json.JSONDecodeError, UnicodeDecodeError):
+ if not isinstance(error, dict):
+ raise ValueError('json error value is not a dict')
+ except (json.JSONDecodeError, UnicodeDecodeError, ValueError):
  logger.error('failed to decode error response: %r', response.content)
  # When the user points to an S3 endpoint, he won't receive the JSON error
  # he expects. In that case, we can provide at least a hint of "what happened".
@@ -439,10 +441,22 @@ def _translate_errors(cls, fcn, post_params=None):
  logger.debug(
  'received error has extra (unsupported) keys: %s', extra_error_keys
  )
+
+ try:
+ status = int(error.get('status', response.status_code))
+ if status != response.status_code:
+ raise ValueError('status code is not equal to the one in the response')
+ except (TypeError, ValueError) as exc:
+ logger.warning(
+ 'Inconsistent status codes returned by the server %r != %r; parsing exception: %r',
+ error.get('status'), response.status_code, exc
+ )
+ status = response.status_code
+
  raise interpret_b2_error(
- int(error.get('status', response.status_code)),
- error.get('code'),
- error.get('message'),
+ status,
+ str(error['code']) if 'code' in error else None,
+ str(error['message']) if 'message' in error else None,
  response.headers,
  post_params,
  )

changelog.d/+handle_invalid_error_format.fixed.md

@@ -0,0 +1 @@
+Handle json encoded, invalid B2 error responses, preventing exceptions such as `invalid literal for int() with base 10: 'service_unavailable'`.

test/unit/b2http/test_b2http.py

@@ -145,6 +145,36 @@ def test_b2_error__nginx_html():
  assert response.content.decode('utf-8') in str(exc_info.value)
 
 
+def test_b2_error__invalid_error_format():
+ """
+ Handling of invalid error format.
+
+ If server returns valid JSON, but not matching B2 error schema, we should still raise ServiceError.
+ """
+ response = MagicMock()
+ response.status_code = 503
+ # valid JSON, but not a valid B2 error (it should be a dict, not a list)
+ response.content = b'[]'
+ with pytest.raises(ServiceError) as exc_info:
+ B2Http._translate_errors(lambda: response)
+ assert '503' in str(exc_info.value)
+
+
+def test_b2_error__invalid_error_values():
+ """
+ Handling of invalid error values.
+
+ If server returns valid JSON, but not matching B2 error schema, we should still raise ServiceError.
+ """
+ response = MagicMock()
+ response.status_code = 503
+ # valid JSON, but not a valid B2 error (code and status values (and therefore types!) are swapped)
+ response.content = b'{"code": 503, "message": "Service temporarily unavailable", "status": "service_unavailable"}'
+ with pytest.raises(ServiceError) as exc_info:
+ B2Http._translate_errors(lambda: response)
+ assert '503 Service temporarily unavailable' in str(exc_info.value)
+
+
 class TestTranslateAndRetry(TestBase):
  def setUp(self):
  self.response = MagicMock()