commit 50a0b1219e71516cc181a7ae7af69b3d249523f4
author Victor Boivie <boivie@webrtc.org> Thu May 06 19:07:49 2021
committer WebRTC LUCI CQ <webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue May 11 16:04:42 2021
tree 8bab69086f2dca7aecc8dfa88bdaf3e4d8247f5b
parent 78d5859bde85263373b869d243cd224770a5881a

dcsctp: Avoid transition back to ShutdownPending

When a socket is shutting down, either explicitly by the ULP calling
Shutdown(), or when the socket receives a SHUTDOWN chunk, the socket
should send all outstanding data and when all is sent and acked,
_then_ it should continue the shutdown protocol.

As it currently doesn't calculate correctly when all data has been sent,
as NACKED chunks are not included in what it believes is remaining in
the retransmission queue, it will shut down prematurely and may go back
to a previous state (ShutdownPending) from ShutdownSent or
ShutdownAckSent.

This is a workaround that just avoids the illegal state transition as
that puts the socket in an inconsistent state. The bug is merely
theoretical as WebRTC doesn't currently gracefully shut down a SCTP
socket, but just terminates the DTLS transport.

As TODOs mention, this will be fixed correctly a bit later.

Bug: webrtc:12739
Change-Id: Ibde2acc3a6aca701ac178d6181028404d470a5d5
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/218340
Reviewed-by: Florent Castelli <orphis@webrtc.org>
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33982}