[libnice] Connection dropped on Windows while fast retransmitting in reliable agent.

Philip Withnall philip at tecnocode.co.uk
Mon Dec 15 15:47:22 PST 2014


On Wed, 2014-11-12 at 15:15 +0100, Radosław Kołodziejczyk wrote:
> Hello,
> Now, this might sound ok, but the problem is that the transmit
> function does not account for EAGAIN or EWOULDBLOCK errors (which are
> not really fatal) and this created a very peculiar race condition that
> gave us a headache. Enable extended logs - problem gone. Add some
> sleep - problem gone. The reason for that is that if the fast
> retransmit happens to be when the socket is (temporarily) busy, our
> connection goes down. If you give sockets a tiny bit of time to flush
> - problem goes away.

That’s a great analysis, and it looks like you’re correct. Thanks a lot
for looking into this, and sorry for taking so long to get to it
myself. :-(

I’ve put together a patch (basically the same approach you took — loop
until the EWOULDBLOCK goes away) and filed a bug:


It will need review, but hopefully should get sorted soon.

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