This allows sending and receiving arbitrarily (we limit to 1 GiB atm) sized
messages while not relying on the deprecated PPID fragmentation/reassembly
mode. The code already supports the ndata extension but it's not activated,
yet. Without the SCTP ndata extension, a large data channel message will
monopolise the SCTP association. While this is a problem, it is a temporary
solution until the extension is being activated. Keep in mind that every
application that uses data channels currently does fragmentation/reassembly on
application-level and it's unlikely that this will change until the popular
implementations (libwebrtc) implement EOR as well. Moreover, until the WebRTC
API specifies an API that hands over partial messages, doing application-level
fragmentation/reassembly is still useful for very large messages (sadly).
We fall back to PPID-based fragmentation/reassembly mode IFF a=max-message-size
is not set in the SDP and the negotiated amount of SCTP inbound streams is
exactly 256. Other implementations should avoid using this combination (to be
precise, other implementations should send a=max-message-size).
It also changes behaviour of RTCDataChannel.send which now raises TypeError in
case the message is too large for the other peer to receive. This is a
necessity to ensure that implementations that do not look at the EOR flag when
receiving are always able to receive our messages. Even if these
implementations do not set a=max-message-size, we use a safe default value (64
KiB, dictated by the spec) that every implementation should be able to receive,
with or without EOR support.
* Due to the use of explicit EOR, this required some major refactoring of all
send-related and deferred sending functions (which is now a lot less
complex). There's now only one place where `usrsctp_sendv` is being used.
* All data channel messages and DCEP messages will be sent without copying them
first. Only in case this fails (e.g. usrsctp's buffer is full), the message
will be copied and added to a buffer queue.
* Queued data channel messages will now be re-sent fairly (round-robin).
* Maximum message size and the PPID-based fragmentation are configurable using
about:config (media.peerconnection.sctp.force_ppid_fragmentation and
media.peerconnection.sctp.force_maximum_message_size).
* Enable interleaving of incoming messages for different streams (preparation
for SCTP ndata, has no effect until it is enabled).
* Enable interleaving of outgoing messages (disabled if SCTP ndata has not been
negotiated).
* Add pending messages flag to reduce performance impact from frequent calls to
SendDeferredMessages.
* Handle partial delivery events (for cases where a partially delivered message
is being aborted).
* Close a data channel/the connection in case the message is too large to be
handled (this is only applied in cases where the remote peer ignores our
announced local maximum message size).
* Various size_t to uint32_t conversions (message length) and back should be
safe now.
* Remove aUsingDtls/mUsingDtls from DataChannelConnection.
* Set maximum message size in SDP and in the data channel stack.
* Replace implicit NS_ENSURE_*'s with explicit NS_WARN_IF's.
* Add SetMaxMessageSize method for late-applying those signalling parameters
when a data channel has been created before the remote SDP was available.
* Limit remote maximum message size and add a GetMaxMessageSize method for a
future implementation of RTCSctpTransport.maxMessageSize.
MozReview-Commit-ID: FlmZrpC5zVI
--HG--
extra : rebase_source : 54e1b838c788a3abbded4fb32fe7c2788f8a9bc0
We have a minimum requirement of VS 2015 for Windows builds, which supports
the z length modifier for format specifiers. So we don't need SizePrintfMacros.h
any more, and can just use %zu and friends directly everywhere.
MozReview-Commit-ID: 6s78RvPFMzv
--HG--
extra : rebase_source : 009ea39eb4dac1c927aa03e4f97d8ab673de8a0e
Dan Minor
Chris Peterson
Andi-Bogdan Postelnicu
Sebastian Hengst
Tristan Bourvon
Nils Ohlmeier [:drno]
Ryan VanderMeulen
Sylvestre Ledru
Randell Jesup
Byron Campen [:bwc]
Andrea Marchesini
Phil Ringnalda
Lennart Grahl
Kartikaya Gupta
Kershaw Chang
Bill McCloskey
Carsten "Tomcat" Book
Bevis Tseng
Wes Kocher
Tom Tromey
Markus Stange