[Cryptography-dev] pyOpenSSL: non-blocking socket support

[Nikolaus Rath]

Hello,

IIAC, when using the standard library's ssl module, the following can
happen (distilled from http://bugs.python.org/issue22499):

1. User calls SSLSocket.send(something)
2. SSLSocket.send raises SSLWantRead (or SSLWantWrite)
3. User calls select() to wait for Read (or write) readyness of the
   underlying fd.
4. User calls SSLSocket.send(something) again
5. SSLSocket.send raises SSLError

If I understand correctly, this is because the ssl module does not
actually implement the 'struct iostate' state machinery required by
OpenSSL and instead just blindly raises SSLWantRead/SSLWantWrite.

Can someone tell me how pyOpenSSL supports non-blocking socket? Does it
also require the caller to maintain struct iostate, or does it allow to
work with just SSLWantRead/Write and select()?


(Background: I'm wondering if switching to pyOpenSSL would be a feasible
way to tackle https://bitbucket.org/nikratio/s3ql/issues/87).


Thanks,
-Nikolaus

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