BUG/MINOR: quic: Do not send too small datagrams (with Initial packets)

Before building a packet into a datagram, ensure there is sufficient space for at
least 1200 bytes. Also pad datagrams with only one ack-eliciting Initial packet
inside.

Must be backported to 2.7 and 2.6.

diff --git a/src/quic_conn.c b/src/quic_conn.c
index ad41c87cf9633da6b819821308f275b873d19872..dbcd4db7634baeca1bd77c07e23cfccacd87ae80 100644 (file)
--- a/src/quic_conn.c
+++ b/src/quic_conn.c
@@ -3320,6 +3320,27 @@ static int qc_prep_pkts(struct quic_conn *qc, struct buffer *buf,
                        }
                }
 
+               /* RFC 9000 14.1 Initial datagram size
+                * a server MUST expand the payload of all UDP datagrams carrying ack-eliciting
+                * Initial packets to at least the smallest allowed maximum datagram size of
+                * 1200 bytes.
+                *
+                * Ensure that no ack-eliciting packets are sent into too small datagrams
+                */
+               if (pkt_type == QUIC_PACKET_TYPE_INITIAL && !LIST_ISEMPTY(tel_frms)) {
+                       if (end - pos < QUIC_INITIAL_PACKET_MINLEN) {
+                               TRACE_PROTO("No more enough room to build an Initial packets",
+                                           QUIC_EV_CONN_PHPKTS, qc);
+                               goto out;
+                       }
+
+                       /* Pad this Initial packet if there is no ack-eliciting frames to send from
+                        * the next packet number space.
+                        */
+                       if (LIST_ISEMPTY(next_tel_frms))
+                               padding = 1;
+               }
+
                if (qc->negotiated_version) {
                        ver = qc->negotiated_version;
                        if (qel == &qc->els[QUIC_TLS_ENC_LEVEL_INITIAL])