MINOR: quic: Splice the frames which could not be added to packets

When building packets to send, we build frames computing their sizes
to have more chance to be added to new packets. There are rare cases
where this packet coult not be built because of the congestion control
which may for instance prevent us from building a packet with padding
(retransmitted Initial packets). In such a case, the pre-built frames
were lost because added to the packet frame list but not move packet
to the packet number space they come from.

With this patch we add the frames to the packet only if it could be built
and move them back to the packet number space if not.

diff --git a/src/xprt_quic.c b/src/xprt_quic.c
index e84e0bfcce0ee4f9b75aeb5ea5d48002e2c16ebf..f9d61e29df17f4f008c1192eb9c644ca149cb6bf 100644 (file)
--- a/src/xprt_quic.c
+++ b/src/xprt_quic.c
@@ -4602,10 +4602,10 @@ static int quic_ack_frm_reduce_sz(struct quic_frame *ack_frm, size_t limit)
  * <headlen> is the number of bytes already present in this packet before building frames.
  *
  * Update consequently <*len> to reflect the size of these frames built
- * by this function. Also attach these frames to <pkt> QUIC packet.
+ * by this function. Also attach these frames to <l> frame list.
  * Return 1 if succeeded, 0 if not.
  */
-static inline int qc_build_frms(struct quic_tx_packet *pkt,
+static inline int qc_build_frms(struct list *l,
                                 size_t room, size_t *len, size_t headlen,
                                 struct quic_enc_level *qel,
                                 struct quic_conn *qc)
@@ -4657,7 +4657,7 @@ static inline int qc_build_frms(struct quic_tx_packet *pkt,
                        if (dlen == cf->crypto.len) {
                                /* <cf> CRYPTO data have been consumed. */
                                LIST_DELETE(&cf->list);
-                               LIST_APPEND(&pkt->frms, &cf->list);
+                               LIST_APPEND(l, &cf->list);
                        }
                        else {
                                struct quic_frame *new_cf;
@@ -4672,7 +4672,7 @@ static inline int qc_build_frms(struct quic_tx_packet *pkt,
                                new_cf->crypto.len = dlen;
                                new_cf->crypto.offset = cf->crypto.offset;
                                new_cf->crypto.qel = qel;
-                               LIST_APPEND(&pkt->frms, &new_cf->list);
+                               LIST_APPEND(l, &new_cf->list);
                                /* Consume <dlen> bytes of the current frame. */
                                cf->crypto.len -= dlen;
                                cf->crypto.offset += dlen;
@@ -4720,7 +4720,7 @@ static inline int qc_build_frms(struct quic_tx_packet *pkt,
                        if (dlen == cf->stream.len) {
                                /* <cf> STREAM data have been consumed. */
                                LIST_DELETE(&cf->list);
-                               LIST_APPEND(&pkt->frms, &cf->list);
+                               LIST_APPEND(l, &cf->list);
                        }
                        else {
                                struct quic_frame *new_cf;
@@ -4742,7 +4742,7 @@ static inline int qc_build_frms(struct quic_tx_packet *pkt,
                                /* FIN bit reset */
                                new_cf->type &= ~QUIC_STREAM_FRAME_TYPE_FIN_BIT;
                                new_cf->stream.data = cf->stream.data;
-                               LIST_APPEND(&pkt->frms, &new_cf->list);
+                               LIST_APPEND(l, &new_cf->list);
                                cf->type |= QUIC_STREAM_FRAME_TYPE_OFF_BIT;
                                /* Consume <dlen> bytes of the current frame. */
                                cf->stream.len -= dlen;
@@ -4760,7 +4760,7 @@ static inline int qc_build_frms(struct quic_tx_packet *pkt,
                        *len += flen;
                        room -= flen;
                        LIST_DELETE(&cf->list);
-                       LIST_APPEND(&pkt->frms, &cf->list);
+                       LIST_APPEND(l, &cf->list);
                        break;
                }
                ret = 1;
@@ -4796,6 +4796,7 @@ static int qc_do_build_pkt(unsigned char *pos, const unsigned char *end,
        size_t ack_frm_len, head_len;
        int64_t largest_acked_pn;
        int add_ping_frm;
+       struct list frm_list = LIST_HEAD_INIT(frm_list);
 
        /* Length field value with CRYPTO frames if present. */
        len_frms = 0;
@@ -4864,7 +4865,7 @@ static int qc_do_build_pkt(unsigned char *pos, const unsigned char *end,
                 * we will have len_frms > len.
                 */
                len_frms = len;
-               if (!qc_build_frms(pkt, end - pos, &len_frms, pos - beg, qel, qc)) {
+               if (!qc_build_frms(&frm_list, end - pos, &len_frms, pos - beg, qel, qc)) {
                        TRACE_PROTO("Not enough room", QUIC_EV_CONN_HPKT,
                                    qc, NULL, NULL, &room);
                }
@@ -4902,7 +4903,7 @@ static int qc_do_build_pkt(unsigned char *pos, const unsigned char *end,
                padding_len -= quic_int_getsize(len + padding_len) - len_sz;
                len += padding_len;
        }
-       else if (LIST_ISEMPTY(&pkt->frms) || len_frms == len) {
+       else if (LIST_ISEMPTY(&frm_list) || len_frms == len) {
                if (qel->pktns->tx.pto_probe) {
                        /* If we cannot send a frame, we send a PING frame. */
                        add_ping_frm = 1;
@@ -4927,11 +4928,10 @@ static int qc_do_build_pkt(unsigned char *pos, const unsigned char *end,
                goto no_room;
 
        /* Ack-eliciting frames */
-       if (!LIST_ISEMPTY(&pkt->frms)) {
+       if (!LIST_ISEMPTY(&frm_list)) {
                struct quic_frame *cf;
 
-               TRACE_PROTO("Ack eliciting frame", QUIC_EV_CONN_HPKT, qc, pkt);
-               list_for_each_entry(cf, &pkt->frms, list) {
+               list_for_each_entry(cf, &frm_list, list) {
                        if (!qc_build_frm(&pos, end, cf, pkt, qc)) {
                                ssize_t room = end - pos;
                                TRACE_PROTO("Not enough room", QUIC_EV_CONN_HPKT,
@@ -4968,10 +4968,14 @@ static int qc_do_build_pkt(unsigned char *pos, const unsigned char *end,
                qel->pktns->tx.pto_probe--;
 
        pkt->len = pos - beg;
+       LIST_SPLICE(&pkt->frms, &frm_list);
+       TRACE_PROTO("Ack eliciting frame", QUIC_EV_CONN_HPKT, qc, pkt);
 
        return 1;
 
  no_room:
+       /* Replace the pre-built frames which could not be add to this packet */
+       LIST_SPLICE(&qel->pktns->tx.frms, &frm_list);
        TRACE_PROTO("Not enough room", QUIC_EV_CONN_HPKT, qc);
        return 0;
 }