On 2017-01-22 21:18, Grant Edwards wrote: > Is the Python SSL API thread-safe with respect to recv() and send()? > > IOW, can I have one thread doing blocking recv() calls on an SSL > connection object while "simultaneously" a second thread is calling > send() on that same connection object? > > I assumed that was allowed, but I can't find anything in the > documentation that actually says it is.
OpenSSL and Python's ssl module are thread-safe. However IO is not safe concerning reentrancy. You cannot safely share a SSLSocket between threads without a mutex. Certain aspects of the TLS protocol can cause interesting side effects. A recv() call can send data across a wire and a send() call can receive data from the wire, e.g. during re-keying. In order to archive reentrancy, you have to do all IO yourself by operating the SSL connection in non-blocking mode or with a Memorio-BIO https://docs.python.org/3/library/ssl.html#ssl-nonblocking -- https://mail.python.org/mailman/listinfo/python-list