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BUG/MINOR: mux-quic: do not close STREAM with empty FIN if no data sent

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A stream may be shut without any HTX EOM reported to report a proper
closure. This is the case for QCS instances flagged with
QC_SF_UNKNOWN_PL_LENGTH. Shut is performed with an empty FIN emission
instead of a RESET_STREAM. This has been implemented since the following
patch :

  24962dd1784dd22babc8da09a5fc8769617f89e3
  BUG/MEDIUM: mux-quic: do not emit RESET_STREAM for unknown length

However, in case of HTTP/3, an empty FIN should only be done after a
full message is emitted, which requires at least a HEADERS frame. If an
empty FIN is emitted without it, client may interpret this as invalid
and close the connection. To prevent this, fallback to a RESET_STREAM
emission if no data were emitted on the stream.

This was reproduced using ngtcp2-client with 10% loss (-r 0.1) on a
remote host, with httpterm request "/?s=100k&C=1&b=0&P=400". An error
ERR_H3_FRAME_UNEXPECTED is returned by ngtcp2-client when the bug
occurs.

Note that this change is incomplete. The message validity depends solely
on the application protocol in use. As such, a new app_ops callback
should be implemented to ensure the stream is closed accordingly.
However, this first patch ensures that at least HTTP/3 case is valid
while keeping a minimal backport process.

This should be backported up to 2.8.

(cherry picked from commit 68c8c910238f0b759d75b4da2128370abf184cd1)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
This commit is contained in:
Amaury Denoyelle 2024-10-18 17:46:06 +02:00 committed by Christopher Faulet
parent 7e69007d4a
commit 260fa5648e
1 changed files with 7 additions and 3 deletions
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10
src/mux_quic.c
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@ -3192,8 +3192,12 @@ static void qmux_strm_shut(struct stconn *sc, unsigned int mode, struct se_abort
if (!qcs_is_close_local(qcs) &&
!(qcs->flags & (QC_SF_FIN_STREAM|QC_SF_TO_RESET))) {
if (qcs->flags & QC_SF_UNKNOWN_PL_LENGTH) {
/* Close stream with a FIN STREAM frame. */
/* Close stream with FIN if length unknown and some data are
* ready to be/already transmitted.
* TODO select closure method on app proto layer
*/
if (qcs->flags & QC_SF_UNKNOWN_PL_LENGTH &&
qcs->tx.fc.off_soft) {
if (!(qcc->flags & (QC_CF_ERR_CONN|QC_CF_ERRL))) {
TRACE_STATE("set FIN STREAM",
QMUX_EV_STRM_SHUT, qcc->conn, qcs);
@ -3296,7 +3300,7 @@ static const struct mux_ops qmux_ops = {
.subscribe = qmux_strm_subscribe,
.unsubscribe = qmux_strm_unsubscribe,
.wake = qmux_wake,
.shut = qmux_strm_shut,
.shut = qmux_strm_shut,
.ctl = qmux_ctl,
.sctl = qmux_sctl,
.show_sd = qmux_strm_show_sd,