Last Comment Bug 658546 - websockets - deflate stream and pywebsockets-07 unclean closes
: websockets - deflate stream and pywebsockets-07 unclean closes
Product: Core
Classification: Components
Component: Networking: WebSockets (show other bugs)
: unspecified
: x86_64 Linux
-- normal (vote)
: ---
Assigned To: Patrick McManus [:mcmanus]
: Patrick McManus [:mcmanus]
Depends on:
Blocks: 640003
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Reported: 2011-05-20 08:43 PDT by Patrick McManus [:mcmanus]
Modified: 2011-06-07 09:04 PDT (History)
3 users (show)
See Also:
Crash Signature:
QA Whiteboard:
Iteration: ---
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Has Regression Range: ---
Has STR: ---

disable deflate-stream pref v1 (1.12 KB, patch)
2011-05-20 08:52 PDT, Patrick McManus [:mcmanus]
cbiesinger: review+
Details | Diff | Splinter Review

Description User image Patrick McManus [:mcmanus] 2011-05-20 08:43:04 PDT
using websockets (ietf-07) in conjunction with pywebsockets (07) and deflate-stream can result in non-clean connection closes once in a while when the client is the first to close. This doesn't happen with deflate-stream disabled.

this can be seen occasionally as an intermittent fail on test_websocket.html or test_ws_basic_tests if deflate stream is enabled.

According to some logging:

* the client js closes the websocket
* the client sends the ws close frame to the server (but no tcp close)
* the server sends a tcp close (eof)

+ one possibility is that the server needs a fix (it is somehow swallowing the ws close it should be sending before the tcp close)..

+ another possibility is that our close is somehow malformed and the tcp close we get from the server is how it reacts to a protocol exception.

+ another possibility is that the end of our compression stream is being interpreted as a tcp close by the server and it is aborting as if we had hung up.

deflate-stream is just an extension and is preffable, so the right thing to do for the immediate term is to just pref it off while I figure out what is going on so the rest of the code can get some experience.
Comment 1 User image Patrick McManus [:mcmanus] 2011-05-20 08:52:55 PDT
Created attachment 533986 [details] [diff] [review]
disable deflate-stream pref v1
Comment 2 User image Patrick McManus [:mcmanus] 2011-05-21 19:37:45 PDT
Comment 3 User image Patrick McManus [:mcmanus] 2011-06-07 09:04:15 PDT
in the end this is a server issue in pywebsockets. the server isn't draining the final framing bytes of the compression before it does a socket close, which results in a RST being generated. This RST can pre-empt the WS close it had already sent in a race condition.

I'll file a different bug about patching the server and re-enabling the extension.

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