[nginx] QUIC: ignore version negotiation packets.

[noreply at nginx.com]

details:   https://github.com/nginx/nginx/commit/0d11f2885eab99924dbe40d7effb91c80b00d9bf
branches:  stable-1.26
commit:    0d11f2885eab99924dbe40d7effb91c80b00d9bf
user:      Roman Arutyunyan <arut at nginx.com>
date:      Fri, 13 Dec 2024 13:25:26 +0400
description:
QUIC: ignore version negotiation packets.

Previously, such packets were treated as long header packets with unknown
version 0, and a version negotiation packet was sent in response.  This
could be used to set up an infinite traffic reflect loop with another nginx
instance.

Now version negotiation packets are ignored.  As per RFC 9000, Section 6.1:

  An endpoint MUST NOT send a Version Negotiation packet in response to
  receiving a Version Negotiation packet.

---
 src/event/quic/ngx_event_quic_transport.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/event/quic/ngx_event_quic_transport.c b/src/event/quic/ngx_event_quic_transport.c
index fba098caa..bb13447b5 100644
--- a/src/event/quic/ngx_event_quic_transport.c
+++ b/src/event/quic/ngx_event_quic_transport.c
@@ -295,6 +295,11 @@ ngx_quic_parse_packet(ngx_quic_header_t *pkt)
         return NGX_ERROR;
     }
 
+    if (pkt->version == 0) {
+        /* version negotiation */
+        return NGX_ERROR;
+    }
+
     if (!ngx_quic_supported_version(pkt->version)) {
         return NGX_ABORT;
     }