[asterisk-dev] [Code Review] 4431: Increase WebSocket frame size and improve large read handling

[David Lee]

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https://reviewboard.asterisk.org/r/4431/
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(Updated Feb. 25, 2015, 2:46 p.m.)


Status
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This change has been marked as submitted.


Review request for Asterisk Developers.


Changes
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Committed in revision 432236


Repository: Asterisk


Description
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Some WebSocket applications, like [chan_respoke][], require a larger
frame size than the default 8k; this patch bumps the default to 16k.
This patch also fixes some problems exacerbated by large frames.

The sanity counter was decremented on every fread attempt in
ws_safe_read(), regardless of whether data was read from the socket or
not. For large frames, this could result in loss of sanity prior to
reading the entire frame. (16k frame / 1448 bytes per segment = 12
segments).

This patch changes the sanity counter so that it only decrements when
fread() doesn't read any bytes. This more closely matches the original
intention of ws_safe_read(), given that the error message is
"Websocket seems unresponsive".

This patch also properly logs EOF conditions, so disconnects are no
longer confused with unresponsive connections.

 [chan_respoke]: https://github.com/respoke/chan_respoke


Diffs
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  /branches/11/res/res_http_websocket.c 431915 

Diff: https://reviewboard.asterisk.org/r/4431/diff/


Testing
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Ran a Node app that continuously send large WebSocket frame to Asterisk.

https://gist.github.com/leedm777/ba6d86468d7646073286

Without the patch, Asterisk fails in less than 10 frames. With the patch, it runs like a boss.


Thanks,

David Lee

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