don't try to create ACK frames if there is nothing to ack
This is a regression introduced by 74458c6db64aa50b01314ac8a2fa3e2394c7965c.
We need to check that there are outstanding packets that need to be
acked before trying to create an ACK frame, otherwise a panic is
triggered when the frame is serialized.
diff --git a/src/lib.rs b/src/lib.rs
index 311502b..691a43b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2085,8 +2085,9 @@
let mut payload_len = 0;
// Create ACK frame.
- if (self.pkt_num_spaces[epoch].ack_elicited ||
- self.recovery.loss_probes[epoch] > 0) &&
+ if self.pkt_num_spaces[epoch].recv_pkt_need_ack.len() > 0 &&
+ (self.pkt_num_spaces[epoch].ack_elicited ||
+ self.recovery.loss_probes[epoch] > 0) &&
!is_closing
{
let ack_delay =
