GRPC server seems to always compress messages even if client does not support it.

[RubenGarcia]

GRPC server seems to always compress messages even if client does not support it. See https://github.com/Cysharp/YetAnotherHttpHandler/issues/19 where client is complaining with the line Request sent 'identity' grpc-encoding value with compressed message. #19

<version of the grpc-dart packages used; see your pubspec.lock file>
grpc:
dependency: "direct main"
description:
name: grpc
sha256: "220ffb2218288f4e7dea487242e08b9c6277596d9b6f3f10ba50be96771a032d"
url: "https://pub.dev"
source: hosted
version: "3.2.3"

Repro steps

1. Generate a dart grpc server
2. Use Unity and YetAnotherHttpHandler to connect to it

Expected result:
The client receives the correct answer

Actual result:
Request sent 'identity' grpc-encoding value with compressed message. #19

[RubenGarcia]

Removing compression using

 codecRegistry: CodecRegistry(codecs: const [/*GzipCodec(), */IdentityCodec()]),

does not make a difference.

[RubenGarcia]

Version: "3.2.4" is also affected.

[RubenGarcia]

Tested on android and on osx, both platforms have the issue.

[RubenGarcia]

After some debugging, these are my results:

• https://grpc.github.io/grpc/core/md_doc_compression.html

  • An ill-constructed message with its Compressed-Flag bit set but lacking a grpc-encoding entry different from identity in its metadata MUST fail with INTERNAL status

• grpc-3.2.4\lib\src\shared\message.dart

  • List frame(List rawPayload, [Codec? codec]) {}
    • when called with codec == IdentityCodec
      • header.setUint8(0, codec == null ? 0 : 1);
        • ^-- this is returning 1 (i.e. the compressed flag is set)
        • message-encoding is set to identity

This means the grpc message is ill-constructed. The correct condition should be

header.setUint8(0, (codec == null || codec.encodingName =="identity") ? 0 : 1);

[RubenGarcia]

Merge request fixing the issue.
#693