[tor-bugs] #28942 [Circumvention/Snowflake]: Evaluate pion WebRTC

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#28942: Evaluate pion WebRTC
-------------------------------------+-------------------------------
 Reporter:  backkem                  |          Owner:  cohosh
     Type:  enhancement              |         Status:  assigned
 Priority:  Medium                   |      Milestone:
Component:  Circumvention/Snowflake  |        Version:
 Severity:  Normal                   |     Resolution:
 Keywords:  ex-sponsor-19            |  Actual Points:
Parent ID:                           |         Points:
 Reviewer:                           |        Sponsor:  Sponsor28-can
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Comment (by cohosh):

 Looking at the [https://tools.ietf.org/html/draft-ietf-rtcweb-data-
 channel-13#section-6.6 webrtc specification] it seems to be a good idea to
 preserve user message boundaries when passing data to OnMessage().

 It also looks like the pion webrtc implementation is set up to check for
 `io.ErrShortBuffer` errors:
 [https://github.com/pion/webrtc/blob/master/datachannel.go#L292
 datachannel.go#L292], but it isn't handled.

 I think I'll go about this by writing two patches:
 - a patch for pion/sctp that correctly forwards the error message
 - a patch for pion/webrtc that calls `ReadDataChannel` again with a larger
 buffer

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28942#comment:15>
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