QUIC: path aware in-flight bytes accounting.

On-packet acknowledgement is made path aware, as per RFC 9000, Section 9.4:
    Packets sent on the old path MUST NOT contribute to congestion control
    or RTT estimation for the new path.

To make this possible in a single congestion control context, the first packet
to be sent after the new path has been validated, which includes resetting the
congestion controller and RTT estimator, is now remembered in the connection.
Packets sent previously, such as on the old path, are not taken into account.

Note that although the packet number is saved per-connection, the added checks
affect application level packets only.  For non-application level packets,
which are only processed prior to the handshake is complete, the remembered
packet number remains set to zero.

diff --git a/src/event/quic/ngx_event_quic_ack.c b/src/event/quic/ngx_event_quic_ack.c
index deeaae1e343df33715337cd9b0acef0663fcd305..c7ffd44dd77e9c9ce8243c394296911deceafd05 100644 (file)
--- a/src/event/quic/ngx_event_quic_ack.c
+++ b/src/event/quic/ngx_event_quic_ack.c
@@ -325,6 +325,10 @@ ngx_quic_congestion_ack(ngx_connection_t *c, ngx_quic_frame_t *f)
     qc = ngx_quic_get_connection(c);
     cg = &qc->congestion;
 
+    if (f->pnum < qc->rst_pnum) {
+        return;
+    }
+
     blocked = (cg->in_flight >= cg->window) ? 1 : 0;
 
     cg->in_flight -= f->plen;
@@ -667,6 +671,10 @@ ngx_quic_congestion_lost(ngx_connection_t *c, ngx_quic_frame_t *f)
     qc = ngx_quic_get_connection(c);
     cg = &qc->congestion;
 
+    if (f->pnum < qc->rst_pnum) {
+        return;
+    }
+
     blocked = (cg->in_flight >= cg->window) ? 1 : 0;
 
     cg->in_flight -= f->plen;

diff --git a/src/event/quic/ngx_event_quic_connection.h b/src/event/quic/ngx_event_quic_connection.h
index ae771bcc59ecfe1e5bd1a6fbc48deab47c5d11cf..824c92b579148406c29ab1135d33d1726da4ada5 100644 (file)
--- a/src/event/quic/ngx_event_quic_connection.h
+++ b/src/event/quic/ngx_event_quic_connection.h
@@ -266,6 +266,8 @@ struct ngx_quic_connection_s {
     ngx_quic_streams_t                streams;
     ngx_quic_congestion_t             congestion;
 
+    uint64_t                          rst_pnum;    /* first on validated path */
+
     off_t                             received;
 
     ngx_uint_t                        error;

diff --git a/src/event/quic/ngx_event_quic_migration.c b/src/event/quic/ngx_event_quic_migration.c
index 58f3fc545a8d6689994c64c85b71254df933b321..3c1bbaf43f02528bc33e6bf23ea625b21ea6191d 100644 (file)
--- a/src/event/quic/ngx_event_quic_migration.c
+++ b/src/event/quic/ngx_event_quic_migration.c
@@ -110,6 +110,7 @@ ngx_quic_handle_path_response_frame(ngx_connection_t *c,
     ngx_uint_t              rst;
     ngx_queue_t            *q;
     ngx_quic_path_t        *path, *prev;
+    ngx_quic_send_ctx_t    *ctx;
     ngx_quic_connection_t  *qc;
 
     qc = ngx_quic_get_connection(c);
@@ -174,6 +175,11 @@ valid:
     }
 
     if (rst) {
+        /* prevent old path packets contribution to congestion control */
+
+        ctx = ngx_quic_get_send_ctx(qc, ssl_encryption_application);
+        qc->rst_pnum = ctx->pnum;
+
         ngx_memzero(&qc->congestion, sizeof(ngx_quic_congestion_t));
 
         qc->congestion.window = ngx_min(10 * qc->tp.max_udp_payload_size,