tree a0fed0a5dca9438abf6cf4c6104924daa235233f
parent 3b08fe3dcddf60f92ef3b09d68b2b449994094f3
author Victor Boivie <boivie@webrtc.org> 1631789900 +0200
committer WebRTC LUCI CQ <webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com> 1631798052 +0000

dcsctp: Move last_assembled_tsn_watermark further

The ReassemblyQueue will need to track which messages that have already
been delivered to the client so that they are not re-delivered on e.g.
retransmissions. It does that by tracking which TSNs that those messages
were built from. It tracks that in two variables,
`last_assembled_tsn_watermark` and `delivered_tsns_`, where the first
one represent that all TSNs including and prior this one have been
delivered and `delivered_tsns` contain additional ones when there are
gaps.

When receiving a FORWARD-TSN and asked to forget about some partially
received messages, these two variables were updated correctly, but the
`delivered_tsns_` were left in a state where it could be adjacent to the
`last_assembled_tsn_watermark` - when `last_assembled_tsn_watermark`
could actually have been moved further.

Added consistency check (that would trigger in existing tests) and
fixing the issue.

This bug is quite benign, as any received chunk would've corrected the
problem, and even at this faulty state, the ReassemblyQueue would
function completely fine.

Bug: webrtc:13154
Change-Id: Iaa7c612999c9dc609fc6e2fb3be2d0bd04534c90
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/232124
Reviewed-by: Florent Castelli <orphis@webrtc.org>
Reviewed-by: Sergey Sukhanov <sergeysu@webrtc.org>
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35013}