`FrameSizeException` when requesting non-TLS hosts

[AlexV525]

• https://github.com/cfug/dio/pull/2220#issuecomment-2118544840
• https://github.com/cfug/dio/actions/runs/9135981572/job/25124169253?pr=2220

Steps to reproduce

1. Clone https://github.com/cfug/dio and enter the directory.
2. melos bs.
3. Run the test with plugins/http2_adapter/test/test_suite_test.dart.

[AlexV525]

When increasing the max frame size to 1 << 24, another exception was thrown: FrameSizeException: Incoming byte stream ended with incomplete frame.

[AlexV525]

This typically happens when the destination is trying to redirect from a non-TLS to a TLS URL.

[AlexV525]

@mosuem

[AlexV525]

Did someone have insights about the cause of the issue and workarounds?

[AlexV525]

Also FYI @brianquinlan

[brianquinlan]

I think that @mosuem is the HTTP2 expert.

[mosuem]

I am very far from an HTTP expert, but I am the maintainer of this library. I am reading into this. The issue is HTTP->HTTP2 redirect handling in this library, correct?

[AlexV525]

I am reading into this. The issue is HTTP->HTTP2 redirect handling in this library, correct?

So far it does.

[mosuem]

I am not familiar with the linked dio library - an example in package:http2 of what type of request you are trying to perform would help, and what the expected behavior is.

[AlexV525]

Oh sure sorry for the inconvenience. I'll bring up a reproducible example with the package only sooner or later next week.

[AlexV525]

Set a breakpoint at:

https://github.com/dart-lang/http/blob/531d3e587c3214ad07bed1f52fac3f01112bc1ed/pkgs/http2/lib/src/connection.dart#L167

Then debug the below example, also change the if (transport is ClientConnection) branch to see different types of FrameSizeException.

import 'dart:convert';
import 'dart:io';

import 'package:http2/http2.dart';
import 'package:http2/src/connection.dart' show ClientConnection;

void main() async {
  final uri = Uri.parse('http://pub.dev/');

  final transport = ClientTransportConnection.viaSocket(
    await Socket.connect(
      uri.host,
      uri.port,
    ),
  );

  // Without the below [maxFrameSize] increment, "Incoming frame is too big" will be thrown.
  // With the below manipulation, "Incoming byte stream ended with incomplete frame" will be thrown.
  if (transport is ClientConnection) {
    transport.acknowledgedSettings.maxFrameSize = 1 << 24;
  }

  final stream = transport.makeRequest(
    [
      Header.ascii(':method', 'GET'),
      Header.ascii(':path', uri.path),
      Header.ascii(':scheme', uri.scheme),
      Header.ascii(':authority', uri.host),
    ],
    endStream: true,
  );

  await for (final message in stream.incomingMessages) {
    if (message is HeadersStreamMessage) {
      for (final header in message.headers) {
        final name = utf8.decode(header.name);
        final value = utf8.decode(header.value);
        print('Header: $name: $value');
      }
    } else if (message is DataStreamMessage) {
      // Use [message.bytes] (but respect 'content-encoding' header)
    }
  }
  await transport.finish();
}

[mosuem]

I get a Unhandled exception: HTTP/2 error: Connection error: Connection is being forcefully terminated. (errorCode: 10) when using your example. It does work when switching to SecureSocket.connect, as in the HTTP2 example.

[AlexV525]

I get a Unhandled exception: HTTP/2 error: Connection error: Connection is being forcefully terminated. (errorCode: 10) when using your example.

You need to set a debug point like my previous comment which is the underlying exception.

It does work when switching to SecureSocket.connect, as in the HTTP2 example.

Should we use SecureSocket regardless of TLS?

[mosuem]

You need to set a debug point like my previous comment which is the underlying exception.

Ah right, now I understand. Let me check.