Amaury Denoyelle bece704128 BUG/MEDIUM: h3: properly encode response after interim one in same buf
Recently, proper support for interim responses forwarding to HTTP/3
client has been implemented. However, there was still an issue if two
responses are both encoded in the same snd_buf() iteration.

The issue is caused due to H3 HEADERS frame encoding method : 5 bytes
are reserved in front of the buffer to encode both H3 frame type and
varint length field. After proper headers encoding, output buffer head
is adjusted so that length can be encoded using the minimal varint size.

However, if the buffer is not empty due to a previous response already
encoded but not yet emitted, messing with the buffer head will corrupt
the entire H3 message. This only happens when encoding of both responses
is done in the same snd_buf() iteration, or at least without emission to
quic_conn layer in between.

The result of this bug is that the HTTP/3 client will be unable to parse
the response, most of the time reporting a formatting error. This can
be reproduced using the following netcat as HTTP/1 server to haproxy :

$ while sleep 0.2; do \
    printf "HTTP/1.1 100 continue\r\n\r\nHTTP/1.1 200 ok\r\nContent-length: 5\r\nConnection: close\r\n\r\nblah\n" | nc -lp8002
  done

To fix this, only adjust buffer head if content is empty. If this is not
the case, frame length is simply encoded as a 4-bytes varint size so
that messages are contiguous in the buffer.

This must be backported up to 2.6.
2025-10-21 15:51:48 +02:00
2025-09-29 19:29:10 +02:00
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2021-09-16 09:14:14 +02:00
2025-10-18 11:24:05 +02:00
2025-10-18 11:24:05 +02:00
2025-10-18 11:24:05 +02:00

HAProxy

alpine/musl AWS-LC openssl no-deprecated Illumos NetBSD FreeBSD VTest

HAProxy logo

HAProxy is a free, very fast and reliable reverse-proxy offering high availability, load balancing, and proxying for TCP and HTTP-based applications.

Installation

The INSTALL file describes how to build HAProxy. A list of packages is also available on the wiki.

Getting help

The discourse and the mailing-list are available for questions or configuration assistance. You can also use the slack or IRC channel. Please don't use the issue tracker for these.

The issue tracker is only for bug reports or feature requests.

Documentation

The HAProxy documentation has been split into a number of different files for ease of use. It is available in text format as well as HTML. The wiki is also meant to replace the old architecture guide.

Please refer to the following files depending on what you're looking for:

  • INSTALL for instructions on how to build and install HAProxy
  • BRANCHES to understand the project's life cycle and what version to use
  • LICENSE for the project's license
  • CONTRIBUTING for the process to follow to submit contributions

The more detailed documentation is located into the doc/ directory:

License

HAProxy is licensed under GPL 2 or any later version, the headers under LGPL 2.1. See the LICENSE file for a more detailed explanation.

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