tree 7fa513cf7f8694bf8e1760eb545f1face731ac45
parent 03f3049df167069f1bf802c18c275524c346513c
author Amaury Denoyelle <adenoyelle@haproxy.com> 1658146310 +0200
committer Amaury Denoyelle <adenoyelle@haproxy.com> 1658222390 +0200

BUG/MINOR: quic: do not send CONNECTION_CLOSE_APP in initial/handshake

As specified by RFC 9000, it is forbidden to send a CONNECTION_CLOSE of
type 0x1d (CONNECTION_CLOSE_APP) in an Initial or Handshake packet. It
must be converted to type 0x1c (CONNECTION_CLOSE) with APPLICATION_ERROR
code.

CONNECTION_CLOSE_APP are generated by QUIC MUX interaction. Thus,
special care must be taken when dealing with a 0-RTT packet, as this is
the only case where the MUX can be instantiated and quic-conn still on
the Initial or Handshake encryption level.

To enforce RFC 9000, xprt build packet function is now responsible to
translate a CONNECTION_CLOSE_APP if still on Initial/Handshake
encryption. This process is done in a dedicated function named
qc_build_cc_frm().

Without this patch, BUG_ON() statement in qc_build_frm() will be
triggered when building a CONNECTION_CLOSE_APP frame on Initial or
Handshake level. This is because QUIC_FT_CONNECTION_CLOSE_APP frame
builder mask does not allow these encryption levels, as opposed to
QUIC_FT_CONNECTION_CLOSE builder. This crash was reproduced by modifying
the H3 layer to force emission of a CONNECTION_CLOSE_APP on first frame
of a 0-RTT session.

Note however that CONNECTION_CLOSE emission during Handshake is a
complicated process for the server. For the moment, this is still
incomplete on haproxy side. RFC 9000 requires to emit it multiple times
in several packets under different encryption levels, depending on what
we know about the client encryption context.

This patch should be backported up to 2.6.