Release 1.19.3

- [BUGFIX] Q044: don't encode packet number in 6 bytes.  Six-byte
  packet number encoding does not exist in Q044.  This fixes a
  regression introduced in '[BUGFIX] Buffered packets can contain
  ACK frames' -- we need to keep QUIC version in mind when selecting
  the longest possible packet number encoding used for the buffered
  packet that carries the ACK.
- [BUGFIX] Do not increase CWND when timeout occurs.
- http_client: support setting handshake timeout on command line.
  Use -o handshake_to=timeout.
- http_client: use -k to connect UDP socket to pick up ICMP errors.
- http_client: allow pathless mode, when only handshake is performed
  without issuing any requests.  This can be done by simply not
  specifying a -p flag on the command line.

src/liblsquic/lsquic_cubic.c

@@ -183,10 +183,14 @@ lsquic_cubic_loss (struct lsquic_cubic *cubic)
 void
 lsquic_cubic_timeout (struct lsquic_cubic *cubic)
 {
+    unsigned long cwnd;
+
+    cwnd = cubic->cu_cwnd;
     LSQ_DEBUG("%s(cubic)", __func__);
     cubic_reset(cubic);
-    cubic->cu_ssthresh = cubic->cu_cwnd;
-    cubic->cu_tcp_cwnd = cubic->cu_cwnd;
+    cubic->cu_ssthresh = cwnd / 2;
+    cubic->cu_tcp_cwnd = 2 * TCP_MSS;
+    cubic->cu_cwnd = 2 * TCP_MSS;
     LSQ_INFO("timeout, cwnd: %lu", cubic->cu_cwnd);
     LOG_CWND(cubic);
 }

src/liblsquic/lsquic_full_conn.c

@@ -2106,6 +2106,7 @@ process_incoming_packet (struct full_conn *conn, lsquic_packet_in_t *packet_in)
             }
             LSQ_DEBUG("end of version negotiation: agreed upon %s",
                                     lsquic_ver2str[conn->fc_ver_neg.vn_ver]);
+            lsquic_send_ctl_verneg_done(&conn->fc_send_ctl);
         }
         return process_regular_packet(conn, packet_in);
     }

src/liblsquic/lsquic_handshake.c

@@ -1923,7 +1923,7 @@ lsquic_enc_session_get_zero_rtt (lsquic_enc_session_t *enc_session,
     sz += sizeof(struct lsquic_zero_rtt_storage);
     if (len < sz)
     {
-        LSQ_DEBUG("client provided buf is too small %lu < %lu", len, sz);
+        LSQ_DEBUG("client provided buf is too small %zu < %zu", len, sz);
         errno = ENOBUFS;
         return -1;
     }

src/liblsquic/lsquic_send_ctl.c

@@ -257,6 +257,7 @@ lsquic_send_ctl_init (lsquic_send_ctl_t *ctl, struct lsquic_alarmset *alset,
     for (i = 0; i < sizeof(ctl->sc_buffered_packets) /
                                 sizeof(ctl->sc_buffered_packets[0]); ++i)
         TAILQ_INIT(&ctl->sc_buffered_packets[i].bpq_packets);
+    ctl->sc_max_packno_bits = PACKNO_LEN_4; /* Safe value before verneg */
 }
 
 
@@ -1698,7 +1699,7 @@ send_ctl_get_buffered_packet (lsquic_send_ctl_t *ctl,
         {
             LSQ_DEBUG("steal ACK frame from low-priority buffered queue");
             ack_action = AA_STEAL;
-            bits = PACKNO_LEN_6;
+            bits = ctl->sc_max_packno_bits;
         }
         /* If ACK can be generated, write it to the first buffered packet. */
         else if (lconn->cn_if->ci_can_write_ack(lconn))
@@ -1709,7 +1710,7 @@ send_ctl_get_buffered_packet (lsquic_send_ctl_t *ctl,
             /* Packet length is set to the largest possible size to guarantee
              * that buffered packet with the ACK will not need to be split.
              */
-            bits = PACKNO_LEN_6;
+            bits = ctl->sc_max_packno_bits;
         }
         else
             goto no_ack_action;
@@ -1781,12 +1782,17 @@ enum lsquic_packno_bits
 lsquic_send_ctl_calc_packno_bits (lsquic_send_ctl_t *ctl)
 {
     lsquic_packno_t smallest_unacked;
+    enum lsquic_packno_bits bits;
     unsigned n_in_flight;
 
     smallest_unacked = lsquic_send_ctl_smallest_unacked(ctl);
     n_in_flight = lsquic_cubic_get_cwnd(&ctl->sc_cubic) / ctl->sc_pack_size;
-    return calc_packno_bits(ctl->sc_cur_packno + 1, smallest_unacked,
+    bits = calc_packno_bits(ctl->sc_cur_packno + 1, smallest_unacked,
                                                             n_in_flight);
+    if (bits <= ctl->sc_max_packno_bits)
+        return bits;
+    else
+        return ctl->sc_max_packno_bits;
 }
 
 
@@ -1929,3 +1935,18 @@ lsquic_send_ctl_mem_used (const struct lsquic_send_ctl *ctl)
 
     return size;
 }
+
+
+void
+lsquic_send_ctl_verneg_done (struct lsquic_send_ctl *ctl)
+{
+    if ((1 << ctl->sc_conn_pub->lconn->cn_version) &
+                                            LSQUIC_GQUIC_HEADER_VERSIONS)
+        ctl->sc_max_packno_bits = PACKNO_LEN_6;
+    else
+        /* Assuming Q044 */
+        ctl->sc_max_packno_bits = PACKNO_LEN_4;
+    LSQ_DEBUG("version negotiation done (%s): max packno bits: %u",
+        lsquic_ver2str[ ctl->sc_conn_pub->lconn->cn_version ],
+        ctl->sc_max_packno_bits);
+}

src/liblsquic/lsquic_send_ctl.h

@@ -89,6 +89,7 @@ typedef struct lsquic_send_ctl {
     }                               sc_cached_bpt;
     unsigned                        sc_next_limit;
     unsigned                        sc_n_scheduled;
+    enum lsquic_packno_bits         sc_max_packno_bits;
 #if LSQUIC_SEND_STATS
     struct {
         unsigned            n_total_sent,
@@ -283,4 +284,7 @@ int
 lsquic_send_ctl_buffered_and_same_prio_as_headers (struct lsquic_send_ctl *,
                                                 const struct lsquic_stream *);
 
+void
+lsquic_send_ctl_verneg_done (struct lsquic_send_ctl *);
+
 #endif