commit d3b186e3d66ec6fb7d1f7c6a7c82bffa08548b33
author Victor Boivie <boivie@webrtc.org> Wed May 05 14:22:29 2021
committer WebRTC LUCI CQ <webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue May 11 08:44:14 2021
tree ece6a4f28eae07018812e95ba4f51788378b31b9
parent cba1e839a07fab5c2cc221f4336ee6cd16958399

dcsctp: Support message with low lifetime

While it's not strictly defined, the expectation is that sending a
message with a lifetime parameter set to zero (0) ms should allow it to
be sent if it can be sent without being buffered. If it can't be
directly sent, it should be discarded.

This is initial support for it. Small messages can now be delivered fine
if they are not to be buffered, but fragmented messages could be partly
sent (if this fills up the congestion window), which means that the
message will then fail to be sent whenever the congestion window frees
up again. It would be better to - at a higher level - realize early that
the message can't be sent in full, and discard it without sending
anything. But that's an optimization that can be done later.

A few off-by-one errors were found when strictly defining that the
message is alive during its entire lifetime. It will expire just _after_
its lifetime.

Sending messages with a lifetime of zero may not supported in all
libraries, so a workaround would be to set a very small timeout instead,
which is tested as well.

Bug: webrtc:12614
Change-Id: I9a00bedb639ad7b3b565b750ef2a49c9020745f1
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/217562
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33977}