Authenticator corrupts request body

[InAnadea]

Steps to Reproduce

When I added an authenticator for ChopperClient, my POST request started giving an HTTP code 400.

Just add an authenticator for the client.

ServerApi.create(
  client: ChopperClient(
    baseUrl: Environment().config.baseUrl,
    authenticator: MyAuthenticator(localDataSource), // here
    errorConverter: const ServerErrorConverter(),
    converter: JsonSerializableConverter(),
    interceptors: [
      ChopperLoggingInterceptor(),
      ChopperCurlInterceptor(),
    ],
  ),
);

class MyAuthenticator extends Authenticator {
  final LocalDataSource localDataSource;

  MyAuthenticator(this.localDataSource);

  @override
  FutureOr<Request?> authenticate(
    Request request,
    Response response, [
    Request? originalRequest,
  ]) async {
    if (response.statusCode == 401) {
      final authModel = await localDataSource.getAuthModelFromCache();
      String newToken = authModel.token;

      final Map<String, String> updatedHeaders =
          Map<String, String>.of(request.headers);

      newToken = 'Bearer $newToken';
      updatedHeaders.update(
        'Authorization',
        (String _) => newToken,
        ifAbsent: () => newToken,
      );
      return request.copyWith(
        headers: updatedHeaders,
      );
    }
    return null;
  }
}

I'm debugged ChopperClient's code and here after authenticator!.authenticate(req, res, request) body converts to string.

Expected results:
The request should save the body type after request.copyWith.

Actual results:
The authenticator converts the body to string.

[Global Loggy] 👻 13:35:37.198690 INFO - --> POST https://xxx/api/administration/add-admin
[Global Loggy] 👻 13:35:37.198868 INFO - content-type: application/json; charset=utf-8
[Global Loggy] 👻 13:35:37.199273 INFO - {"email":"asdf@asdf.asdf"}
[Global Loggy] 👻 13:35:37.199460 INFO - --> END POST (26-byte body)

[Global Loggy] 👻 13:35:39.315634 INFO - --> POST https://xxx/api/administration/add-admin
[Global Loggy] 👻 13:35:39.316050 INFO - content-type: application/json; charset=utf-8
[Global Loggy] 👻 13:35:39.316252 INFO - Authorization: xxxx
[Global Loggy] 👻 13:35:39.316526 INFO - "{\"email\":\"asdf@asdf.asdf\"}"
[Global Loggy] 👻 13:35:39.316773 INFO - --> END POST (32-byte body)

Code sample

ServerApi.create(
  client: ChopperClient(
    baseUrl: Environment().config.baseUrl,
    authenticator: MyAuthenticator(localDataSource), // here
    errorConverter: const ServerErrorConverter(),
    converter: JsonSerializableConverter(),
    interceptors: [
      ChopperLoggingInterceptor(),
      ChopperCurlInterceptor(),
    ],
  ),
);

class MyAuthenticator extends Authenticator {
  final LocalDataSource localDataSource;

  MyAuthenticator(this.localDataSource);

  @override
  FutureOr<Request?> authenticate(
    Request request,
    Response response, [
    Request? originalRequest,
  ]) async {
    if (response.statusCode == 401) {
      final authModel = await localDataSource.getAuthModelFromCache();
      String newToken = authModel.token;

      final Map<String, String> updatedHeaders =
          Map<String, String>.of(request.headers);

      newToken = 'Bearer $newToken';
      updatedHeaders.update(
        'Authorization',
        (String _) => newToken,
        ifAbsent: () => newToken,
      );
      return request.copyWith(
        headers: updatedHeaders,
      );
    }
    return null;
  }
}

Logs

[Global Loggy] 👻 13:35:37.198690 INFO - --> POST https://xxx/api/administration/add-admin
[Global Loggy] 👻 13:35:37.198868 INFO - content-type: application/json; charset=utf-8
[Global Loggy] 👻 13:35:37.199273 INFO - {"email":"asdf@asdf.asdf"}
[Global Loggy] 👻 13:35:37.199460 INFO - --> END POST (26-byte body)

[Global Loggy] 👻 13:35:39.315634 INFO - --> POST https://xxx/api/administration/add-admin
[Global Loggy] 👻 13:35:39.316050 INFO - content-type: application/json; charset=utf-8
[Global Loggy] 👻 13:35:39.316252 INFO - Authorization: xxxx
[Global Loggy] 👻 13:35:39.316526 INFO - "{\"email\":\"asdf@asdf.asdf\"}"
[Global Loggy] 👻 13:35:39.316773 INFO - --> END POST (32-byte body)

Dart SDK version: 2.18.2 (stable) (Tue Sep 27 13:24:11 2022 +0200) on "macos_arm64"

[techouse]

Confirmed. I was able to replicate this in a test case.

The Authenticator I used is pretty vanilla.

class FakeAuthenticator extends Authenticator {
  @override
  FutureOr<Request?> authenticate(
    Request request,
    Response response, [
    Request? originalRequest,
  ]) async {
    if (response.statusCode == 401) {
      return request.copyWith(
        headers: <String, String>{
          ...request.headers,
          'authorization': 'some_fake_token',
        },
      );
    }

    return null;
  }
}

This assertion here fails after triggering the Authenticator.

Expected: '{"name":"john","surname":"doe"}'
  Actual: '"{\\"name\\":\\"john\\",\\"surname\\":\\"doe\\"}"'
   Which: is different.
          Expected: {"name":"j ...
            Actual: "{\\"name\ ...
                    ^
           Differ at offset 0

If the Authenticator is not triggered it passes.

It also affects PATCH and PUT methods, as they too send a body. GET is unaffected.

@InAnadea Until I hopefully fix this I suggest you pre-authenticate before attempting any POST calls.

[techouse]

#390 should fix it.

@InAnadea can you please check out the PR or https://github.com/techouse/chopper/tree/fix-authenticator-corrupting-body and confirm that it all works?