MINOR: quic: Speeding up handshake completion

If a client resend Initial CRYPTO data, this is because it did not receive all
the server Initial CRYPTO data. With this patch we prepare a fast retransmission
without waiting for the PTO timer expiration sending old Initial CRYPTO data,
coalescing them with Handshake CRYPTO if present in the same datagram. Furthermore
we send also a datagram made of previously sent Hanshashke CRYPTO data if any.

diff --git a/src/xprt_quic.c b/src/xprt_quic.c
index 2604f83678614c001e8e97dce4e7deefa250d4a8..c1163bc3a008f99282526791060098300ffd31cf 100644 (file)
--- a/src/xprt_quic.c
+++ b/src/xprt_quic.c
@@ -2199,17 +2199,14 @@ static inline int qc_handle_strm_frm(struct quic_rx_packet *pkt,
                return qc_handle_bidi_strm_frm(pkt, strm_frm, qc);
 }
 
-/* Prepare a fast retransmission from <qel> encryption level
- * which must be Initial encryption level.
- */
+/* Prepare a fast retransmission from <qel> encryption level */
 static void qc_prep_fast_retrans(struct quic_enc_level *qel,
                                  struct quic_conn *qc)
 {
        struct eb_root *pkts = &qel->pktns->tx.pkts;
-       struct eb64_node *node = eb64_first(pkts);
+       struct eb64_node *node;
        struct quic_tx_packet *pkt;
 
- start:
        pkt = NULL;
        pkts = &qel->pktns->tx.pkts;
        node = eb64_first(pkts);
@@ -2225,12 +2222,67 @@ static void qc_prep_fast_retrans(struct quic_enc_level *qel,
                return;
 
        qc_requeue_nacked_pkt_tx_frms(qc, &pkt->frms, &qel->pktns->tx.frms);
-       if (qel == &qc->els[QUIC_TLS_ENC_LEVEL_INITIAL] &&
-           qc->els[QUIC_TLS_ENC_LEVEL_HANDSHAKE].pktns->tx.in_flight) {
-               qc->els[QUIC_TLS_ENC_LEVEL_HANDSHAKE].pktns->tx.pto_probe = 1;
-               qel = &qc->els[QUIC_TLS_ENC_LEVEL_HANDSHAKE];
+}
+
+/* Prepare a fast retransmission during handshake after a client
+ * has resent Initial packets. According to the RFC a server may retransmit
+ * up to two datagrams of Initial packets if did not receive all Initial packets
+ * and resend them coalescing with others (Handshake here).
+ * (Listener only).
+ */
+static void qc_prep_hdshk_fast_retrans(struct quic_conn *qc)
+{
+       struct list itmp = LIST_HEAD_INIT(itmp);
+       struct list htmp = LIST_HEAD_INIT(htmp);
+       struct quic_frame *frm, *frmbak;
+
+       struct quic_enc_level *iqel = &qc->els[QUIC_TLS_ENC_LEVEL_INITIAL];
+       struct quic_enc_level *hqel = &qc->els[QUIC_TLS_ENC_LEVEL_HANDSHAKE];
+       struct quic_enc_level *qel = iqel;
+       struct eb_root *pkts;
+       struct eb64_node *node;
+       struct quic_tx_packet *pkt;
+       struct list *tmp = &itmp;
+
+ start:
+       pkt = NULL;
+       pkts = &qel->pktns->tx.pkts;
+       node = eb64_first(pkts);
+       /* Skip the empty packet (they have already been retransmitted) */
+       while (node) {
+               pkt = eb64_entry(&node->node, struct quic_tx_packet, pn_node);
+               if (!LIST_ISEMPTY(&pkt->frms))
+                       break;
+               node = eb64_next(node);
+       }
+
+       if (!pkt)
+               goto end;
+
+       qel->pktns->tx.pto_probe += 1;
+ requeue:
+       list_for_each_entry_safe(frm, frmbak, &pkt->frms, list) {
+               TRACE_PROTO("to resend frame", QUIC_EV_CONN_PRSAFRM, qc, frm);
+               LIST_DELETE(&frm->list);
+               LIST_APPEND(tmp, &frm->list);
+       }
+
+       if (qel == iqel) {
+               if (pkt->next && pkt->next->type == QUIC_PACKET_TYPE_HANDSHAKE) {
+                       pkt = pkt->next;
+                       tmp = &htmp;
+                       hqel->pktns->tx.pto_probe += 1;
+                       goto requeue;
+               }
+
+               qel = hqel;
+               tmp = &htmp;
                goto start;
        }
+
+ end:
+       LIST_SPLICE(&iqel->pktns->tx.frms, &itmp);
+       LIST_SPLICE(&hqel->pktns->tx.frms, &htmp);
 }
 
 /* Parse all the frames of <pkt> QUIC packet for QUIC connection with <ctx>
@@ -2399,11 +2451,8 @@ static int qc_parse_pkt_frms(struct quic_rx_packet *pkt, struct ssl_sock_ctx *ct
                }
        }
 
-       if (fast_retrans) {
-               qc_prep_fast_retrans(qel, qc);
-               if (qc->els[QUIC_TLS_ENC_LEVEL_HANDSHAKE].pktns->tx.in_flight)
-                       qc_prep_fast_retrans(&qc->els[QUIC_TLS_ENC_LEVEL_HANDSHAKE], qc);
-       }
+       if (fast_retrans)
+               qc_prep_hdshk_fast_retrans(qc);
 
        /* The server must switch from INITIAL to HANDSHAKE handshake state when it
         * has successfully parse a Handshake packet. The Initial encryption must also