[nginx] QUIC: use last client dcid to receive initial packets.

[Roman Arutyunyan]

details:   https://hg.nginx.org/nginx/rev/8f7e6d8c061e
branches:  
changeset: 9153:8f7e6d8c061e
user:      Roman Arutyunyan <arut at nginx.com>
date:      Wed Aug 30 11:09:21 2023 +0400
description:
QUIC: use last client dcid to receive initial packets.

Previously, original dcid was used to receive initial client packets in case
server initial response was lost.  However, last dcid should be used instead.
These two are the same unless retry is used.  In case of retry, client resends
initial packet with a new dcid, that is different from the original dcid.  If
server response is lost, the client resends this packet again with the same
dcid.  This is shown in RFC 9000, 7.3. Authenticating Connection IDs, Figure 8.

The issue manifested itself with creating multiple server sessions in response
to each post-retry client initial packet, if server response is lost.

diffstat:

 src/event/quic/ngx_event_quic.c        |  2 +-
 src/event/quic/ngx_event_quic_socket.c |  4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diffs (26 lines):

diff -r 2880f60a80c3 -r 8f7e6d8c061e src/event/quic/ngx_event_quic.c
--- a/src/event/quic/ngx_event_quic.c	Fri Aug 25 13:51:38 2023 +0400
+++ b/src/event/quic/ngx_event_quic.c	Wed Aug 30 11:09:21 2023 +0400
@@ -1110,7 +1110,7 @@ ngx_quic_discard_ctx(ngx_connection_t *c
     }
 
     if (level == ssl_encryption_initial) {
-        /* close temporary listener with odcid */
+        /* close temporary listener with initial dcid */
         qsock = ngx_quic_find_socket(c, NGX_QUIC_UNSET_PN);
         if (qsock) {
             ngx_quic_close_socket(c, qsock);
diff -r 2880f60a80c3 -r 8f7e6d8c061e src/event/quic/ngx_event_quic_socket.c
--- a/src/event/quic/ngx_event_quic_socket.c	Fri Aug 25 13:51:38 2023 +0400
+++ b/src/event/quic/ngx_event_quic_socket.c	Wed Aug 30 11:09:21 2023 +0400
@@ -93,8 +93,8 @@ ngx_quic_open_sockets(ngx_connection_t *
 
     tmp->sid.seqnum = NGX_QUIC_UNSET_PN; /* temporary socket */
 
-    ngx_memcpy(tmp->sid.id, pkt->odcid.data, pkt->odcid.len);
-    tmp->sid.len = pkt->odcid.len;
+    ngx_memcpy(tmp->sid.id, pkt->dcid.data, pkt->dcid.len);
+    tmp->sid.len = pkt->dcid.len;
 
     if (ngx_quic_listen(c, qc, tmp) != NGX_OK) {
         goto failed;