PeerConnection now has a new setting in RTCConfiguration to enable use of
datagram transport for data channels. There is also a corresponding field
trial, which has both a kill-switch and a way to change the default value.
PeerConnection's interaction with MediaTransport for data channels has been
refactored to work with DataChannelTransportInterface instead.
Adds a DataChannelState and OnStateChanged() to the DataChannelSink
callbacks. This allows PeerConnection to listen to the data channel's
state directly, instead of indirectly by monitoring media transport
state. This is necessary to enable use of non-media-transport (eg.
datagram transport) data channel transports.
For now, PeerConnection watches the state through MediaTransport as well.
This will persist until MediaTransport implements the new callback.
Datagram transport use is negotiated. As such, an offer that requests to use
datagram transport for data channels may be rejected by the answerer. If the
offer includes DTLS, the data channels will be negotiated as SCTP/DTLS data
channels with an extra x-opaque parameter for datagram transport. If the
opaque parameter is rejected (by an answerer without datagram support), the
offerer may fall back to SCTP.
If DTLS is not enabled, there is no viable fallback. In this case, the data
channels are negotiated as media transport data channels. If the receiver does
not understand the x-opaque line, it will reject these data channels, and the
offerer's data channels will be closed.
Bug: webrtc:9719
Change-Id: Ic1bf3664c4bcf9d754482df59897f5f72fe68fcc
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/147702
Commit-Queue: Bjorn Mellem <mellem@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28932}
Note that api/ code is not exempt from the “.h and .cc files come in
pairs” rule, so if you declare something in api/path/to/foo.h, it should be
defined in api/path/to/foo.cc.
Headers in api/ should, if possible, not #include headers outside api/.
It’s not always possible to avoid this, but be aware that it adds to a small
mountain of technical debt that we’re trying to shrink.
.cc files in api/, on the other hand, are free to #include headers
outside api/.
That is, the preferred way for api/ code to access non-api/ code is to call
it from a .cc file, so that users of our API headers won’t transitively
#include non-public headers.
For headers in api/ that need to refer to non-public types, forward
declarations are often a lesser evil than including non-public header files. The
usual rules still apply, though.
.cc files in api/ should preferably be kept reasonably small. If a
substantial implementation is needed, consider putting it with our non-public
code, and just call it from the api/.cc file.
b689af4c99