details: https://hg.nginx.org/nginx/rev/618132842e7c
branches:
changeset: 9191:618132842e7c
user: Roman Arutyunyan <a...@nginx.com>
date: Wed Nov 22 14:48:12 2023 +0400
description:
QUIC: ignore duplicate PATH_CHALLENGE frames.
According to RFC 9000, an endpoint SHOULD NOT send multiple PATH_CHALLENGE
frames in a single packet. The change adds a check to enforce this claim to
optimize server behavior. Previously each PATH_CHALLENGE always resulted in a
single response datagram being sent to client. The effect of this was however
limited by QUIC flood protection.
Also, PATH_CHALLENGE is explicitly disabled in Initial and Handshake levels,
see RFC 9000, Table 3. However, technically it may be sent by client in 0-RTT
over a new path without actual migration, even though the migration itself is
prohibited during handshake. This allows client to coalesce multiple 0-RTT
packets each carrying a PATH_CHALLENGE and end up with multiple PATH_CHALLENGEs
per datagram. This again leads to suboptimal behavior, see above. Since the
purpose of sending PATH_CHALLENGE frames in 0-RTT is unclear, these frames are
now only allowed in 1-RTT. For 0-RTT they are silently ignored.
diffstat:
src/event/quic/ngx_event_quic_migration.c | 8 ++++++++
src/event/quic/ngx_event_quic_transport.h | 1 +
2 files changed, 9 insertions(+), 0 deletions(-)
diffs (29 lines):
diff -r 3a67dd34b6cc -r 618132842e7c src/event/quic/ngx_event_quic_migration.c
--- a/src/event/quic/ngx_event_quic_migration.c Wed Nov 22 14:52:21 2023 +0400
+++ b/src/event/quic/ngx_event_quic_migration.c Wed Nov 22 14:48:12 2023 +0400
@@ -40,6 +40,14 @@ ngx_quic_handle_path_challenge_frame(ngx
ngx_quic_frame_t frame, *fp;
ngx_quic_connection_t *qc;
+ if (pkt->level != ssl_encryption_application || pkt->path_challenged) {
+ ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, 0,
+ "quic ignoring PATH_CHALLENGE");
+ return NGX_OK;
+ }
+
+ pkt->path_challenged = 1;
+
qc = ngx_quic_get_connection(c);
ngx_memzero(&frame, sizeof(ngx_quic_frame_t));
diff -r 3a67dd34b6cc -r 618132842e7c src/event/quic/ngx_event_quic_transport.h
--- a/src/event/quic/ngx_event_quic_transport.h Wed Nov 22 14:52:21 2023 +0400
+++ b/src/event/quic/ngx_event_quic_transport.h Wed Nov 22 14:48:12 2023 +0400
@@ -336,6 +336,7 @@ typedef struct {
unsigned retried:1;
unsigned first:1;
unsigned rebound:1;
+ unsigned path_challenged:1;
} ngx_quic_header_t;
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