BUG/MINOR: quic: Too much prepared retransmissions due to anti-amplification

We must not re-enqueue frames if we can detect in advance they will not be
transmitted due to the anti-amplification limit.

diff --git a/src/xprt_quic.c b/src/xprt_quic.c
index 5917518710304b934c98f2c11abc7993595fe050..e201a91596365240129fbfb2111da40fbf85b6f3 100644 (file)
--- a/src/xprt_quic.c
+++ b/src/xprt_quic.c
@@ -2297,6 +2297,15 @@ static void qc_prep_fast_retrans(struct quic_enc_level *qel,
        if (!pkt)
                return;
 
+       /* When building a packet from another one, the field which may increase the
+        * packet size is the packet number. And the maximum increase is 4 bytes.
+        */
+       if (!quic_peer_validated_addr(qc) && qc_is_listener(qc) &&
+           pkt->len + 4 > 3 * qc->rx.bytes - qc->tx.prep_bytes) {
+               TRACE_PROTO("anti-amplification limit would be reached", QUIC_EV_CONN_PRSAFRM, qc);
+               return;
+       }
+
        qc_requeue_nacked_pkt_tx_frms(qc, &pkt->frms, &qel->pktns->tx.frms);
 }
 
@@ -2344,6 +2353,15 @@ static void qc_prep_hdshk_fast_retrans(struct quic_conn *qc)
        if (!pkt)
                goto end;
 
+       /* When building a packet from another one, the field which may increase the
+        * packet size is the packet number. And the maximum increase is 4 bytes.
+        */
+       if (!quic_peer_validated_addr(qc) && qc_is_listener(qc) &&
+           pkt->len + 4 > 3 * qc->rx.bytes - qc->tx.prep_bytes) {
+               TRACE_PROTO("anti-amplification limit would be reached", QUIC_EV_CONN_PRSAFRM, qc);
+               goto end;
+       }
+
        qel->pktns->tx.pto_probe += 1;
  requeue:
        list_for_each_entry_safe(frm, frmbak, &pkt->frms, list) {