commit 487f9a17e426fd14bb06b13e861071b3f15d119b
author Bjorn A Mellem <mellem@webrtc.org> Mon Sep 09 20:11:49 2019
committer Commit Bot <commit-bot@chromium.org> Mon Sep 09 21:58:36 2019
tree 8e0b07f0d348ebd6aeef060ee15a32304fad3e84
parent 116ffe7e5be4aef2d5641e71f653118a95cabf0c

Reland "Refactor SCTP data channels to use DataChannelTransportInterface."

Also clears SctpTransport before deleting JsepTransport.

SctpTransport is ref-counted, but the underlying transport is deleted when
JsepTransport clears the rtp_dtls_transport.  This results in crashes when
usrsctp attempts to send outgoing packets through a dangling pointer to the
underlying transport.

Clearing SctpTransport before DtlsTransport removes the pointer to the
underlying transport before it becomes invalid.

This fixes a crash in chromium's web platform tests (see
https://chromium-review.googlesource.com/c/chromium/src/+/1776711).

Original change's description:
> Refactor SCTP data channels to use DataChannelTransportInterface.
>
> This change moves SctpTransport to be owned by JsepTransport, which now
> holds a DataChannelTransport implementation for SCTP when it is used for
> data channels.
>
> This simplifies negotiation and fallback to SCTP.  Negotiation can now
> use a composite DataChannelTransport, just as negotiation for RTP uses a
> composite RTP transport.
>
> PeerConnection also has one fewer way it needs to manage data channels.
> It now handles SCTP and datagram- or media-transport-based data channels
> the same way.
>
> There are a few leaky abstractions left.  For example, PeerConnection
> calls Start() on the SctpTransport at a particular point in negotiation,
> but does not need to call this for other transports.  Similarly, PC
> exposes an interface to the SCTP transport directly to the user; there
> is no equivalent for other transports.

Bug: webrtc:9719
Change-Id: I64e94b88afb119fdbf5f22750f88c8a084d53937
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/151981
Reviewed-by: Benjamin Wright <benwright@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Commit-Queue: Benjamin Wright <benwright@webrtc.org>
Commit-Queue: Bjorn Mellem <mellem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29120}