From b8aa869a6f4ee0fda4ab32d5c002fc10bd738079 Mon Sep 17 00:00:00 2001
From: Vladimir Homutov <vl@nginx.com>
Date: Mon, 29 Nov 2021 11:49:09 +0300
Subject: [PATCH] QUIC: refactored multiple QUIC packets handling.

Single UDP datagram may contain multiple QUIC datagrams.  In order to
facilitate handling of such cases, 'first' flag in the ngx_quic_header_t
structure is introduced.
---
 src/event/quic/ngx_event_quic.c           | 13 ++++++++-----
 src/event/quic/ngx_event_quic_migration.c |  7 +------
 src/event/quic/ngx_event_quic_transport.h |  1 +
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/src/event/quic/ngx_event_quic.c b/src/event/quic/ngx_event_quic.c
index af6f3e69e..53e50a8b9 100644
--- a/src/event/quic/ngx_event_quic.c
+++ b/src/event/quic/ngx_event_quic.c
@@ -358,7 +358,7 @@ ngx_quic_process_stateless_reset(ngx_connection_t *c, ngx_quic_header_t *pkt)
     qc = ngx_quic_get_connection(c);
 
     /* A stateless reset uses an entire UDP datagram */
-    if (pkt->raw->start != pkt->data) {
+    if (!pkt->first) {
         return NGX_DECLINED;
     }
 
@@ -666,7 +666,7 @@ static ngx_int_t
 ngx_quic_input(ngx_connection_t *c, ngx_buf_t *b, ngx_quic_conf_t *conf)
 {
     size_t                  size;
-    u_char                 *p;
+    u_char                 *p, *start;
     ngx_int_t               rc;
     ngx_uint_t              good;
     ngx_quic_header_t       pkt;
@@ -676,7 +676,7 @@ ngx_quic_input(ngx_connection_t *c, ngx_buf_t *b, ngx_quic_conf_t *conf)
 
     size = b->last - b->pos;
 
-    p = b->pos;
+    p = start = b->pos;
 
     while (p < b->last) {
 
@@ -685,6 +685,7 @@ ngx_quic_input(ngx_connection_t *c, ngx_buf_t *b, ngx_quic_conf_t *conf)
         pkt.data = p;
         pkt.len = b->last - p;
         pkt.log = c->log;
+        pkt.first = (p == start) ? 1 : 0;
         pkt.flags = p[0];
         pkt.raw->pos++;
 
@@ -979,8 +980,10 @@ ngx_quic_process_payload(ngx_connection_t *c, ngx_quic_header_t *pkt)
 
     pkt->decrypted = 1;
 
-    if (ngx_quic_update_paths(c, pkt) != NGX_OK) {
-        return NGX_ERROR;
+    if (pkt->first) {
+        if (ngx_quic_update_paths(c, pkt) != NGX_OK) {
+            return NGX_ERROR;
+        }
     }
 
     if (c->ssl == NULL) {
diff --git a/src/event/quic/ngx_event_quic_migration.c b/src/event/quic/ngx_event_quic_migration.c
index bea51081d..4f7ab2c97 100644
--- a/src/event/quic/ngx_event_quic_migration.c
+++ b/src/event/quic/ngx_event_quic_migration.c
@@ -388,12 +388,7 @@ ngx_quic_update_paths(ngx_connection_t *c, ngx_quic_header_t *pkt)
 
 update:
 
-    if (pkt->raw->start == pkt->data) {
-        len = pkt->raw->last - pkt->raw->start;
-
-    } else {
-        len = 0;
-    }
+    len = pkt->raw->last - pkt->raw->start;
 
     /* TODO: this may be too late in some cases;
      *       for example, if error happens during decrypt(), we cannot
diff --git a/src/event/quic/ngx_event_quic_transport.h b/src/event/quic/ngx_event_quic_transport.h
index 2d30b010c..2cd372cba 100644
--- a/src/event/quic/ngx_event_quic_transport.h
+++ b/src/event/quic/ngx_event_quic_transport.h
@@ -334,6 +334,7 @@ typedef struct {
     unsigned                                    decrypted:1;
     unsigned                                    validated:1;
     unsigned                                    retried:1;
+    unsigned                                    first:1;
 } ngx_quic_header_t;