tree 29948684c1810b802da6319ffba3e0bc730c7600
parent 462209849f4c144a14ba1233b01ca7ea4d9b3382
author martinduke <martinduke@google.com> 1673546684 -0800
committer Copybara-Service <copybara-worker@google.com> 1673546735 -0800

Receive ECN marks on inbound packets and report counts in ACK_ECN frames.
It does not support marking outbound packets except for a minimal capability for test.

QuicPacketReader receives ECN marks from the socket API via QuicUdpPacketInfo.. QuicPacketReader then stores this in a new member of QuicReceivedPacket. This arrives at QuicConnection, which adds to the last_received_packet_info_. When the framer calls QuicConnection::OnPacketHeader(), QuicConnection updates the pending ack frame with the new ECN count via QuicReceivedPacketManager, which updates the counts in the ack frame.

To enable an end-to-end test, this CL also includes minimal changes to mark outbound packets and report the contents of ACK_ECN frames.

QuicConnection::per_packet_options_ is extended to include an ECN codepoint, which QuicDefaultPacketWriter reads, and passes the instruction to the QuicUdpSocketApi via QuicUdpPacketInfo. The test explicitly sets per_packet_options_ to mark ECT(0) after the handshake.

When receiving ACK_ECN, the results are reported to QuicConnection in OnAckFrameEnd(), which then just stores them in a new data structure QuicEcnCounts.

Protected by FLAGS_quic_reloadable_flag_quic_receive_ecn.

PiperOrigin-RevId: 501596181