Copy the ECN codepoint in QuicReceivedPacket::Clone().

Cloned incoming packets will not carry a ECN codepoint even when the original packet has one, so the resulting ECN feedback will be incorrect -- this will cause the peer to abandon ECN, potentially impairing performance.

The relevant instance of cloned packets is Buffered Packets at the beginning of the connection. ECN peers will abandon ECN if early packets are buffered.

The only other instance is the QuicProxyConnectionMap. Fixing Clone() is necessary but not sufficient for getting QuicProxyDispatcher to forward ECN properly.

There are tests for both downstream effects of this bug.

Protected by FLAGS_quic_reloadable_flag_quic_clone_ecn.

PiperOrigin-RevId: 595547494
10 files changed
tree: 090388b308bfda4b9e99b4eaa5e7e1706b6ce6b5
  1. build/
  2. depstool/
  3. quiche/
  4. .bazelrc
  5. .bazelversion
  6. BUILD.bazel
  11. WORKSPACE.bazel


QUICHE stands for QUIC, Http, Etc. It is Google‘s production-ready implementation of QUIC, HTTP/2, HTTP/3, and related protocols and tools. It powers Google’s servers, Chromium, Envoy, and other projects. It is actively developed and maintained.

There are two public QUICHE repositories. Either one may be used by embedders, as they are automatically kept in sync:

To embed QUICHE in your project, platform APIs need to be implemented and build files need to be created. Note that it is on the QUICHE team's roadmap to include default implementation for all platform APIs and to open-source build files. In the meanwhile, take a look at open source embedders like Chromium and Envoy to get started:

To contribute to QUICHE, follow instructions at

QUICHE is only supported on little-endian platforms.