Ack block length should be 1 (not sure)
@@ -732,8 +732,9 @@ ssize_t ngtcp2_pkt_encode_ack_frame(uint8_t *out, size_t outlen,
*p++ = 0;
p = ngtcp2_put_uint48be(p, fm->largest_ack);
p = ngtcp2_put_uint16be(p, fm->ack_delay);
- /* Just ack 1 packet */
- p = ngtcp2_put_uint48be(p, 1);
+ /* I'm not sure this should be 0 or 1. "Additional" means this
+ should be 0. */
+ p = ngtcp2_put_uint48be(p, 0);
assert((size_t)(p - out) == len);
