My understanding is that yes, on that given socket, you have to do only what it needs according to the error code. In this case, SSL_ERROR_WANT_WRITE indicates you should select on write and try SSL_write() again before doing an SSL_read() on that socket. Of course, you can read and write on other sockets in the meantime.
For an implementation, an SSL_ERROR_WANT_WRITE means add the socket to the list of sockets to select() for writing and delete from the list for reading, and SSL_ERROR_WANT_READ means add the socket for reading and delete it for writing. But note that SSL_ERROR_WANT_WRITE doesn't imply SSL_write() comes next, and SSL_ERROR_WANT_READ doesn't imply SSL_read() comes next, because the interrupting handshake is two-way. Also note that SSL_accept() and SSL_shutdown() require similar handling. For non-blocking IO, here's a simple set of tables consolidated from the docs that is useful for a possible general switch structure: http://jmarshall.com/wiki/bin/view/Main/NonBlockingIOinOpenSSL . I'm pretty sure it's correct, but I'm not an expert. It could definitely be improved-- as I recall my structure was to select(), then for each socket switch on its error code, then do the appropriate next operation (which for SSL_ERROR_WANT_READ or SSL_ERROR_WANT_WRITE is just a repeat of its previous operation). Good luck, James On Thu, Sep 19, 2013 at 2:02 AM, Krzysztof Kwiatkowski <krzys...@leeds.pl>wrote: > Hi, > > I'm a bit confused about usage of SSL_write()/SSL_read() in non-blocking > connectors. Let say I do SSL_write() and I get SSL_ERROR_WANT_WRITE. It > means I have to do SSL_write() again. But does it mean that I can't do > SSL_read() until SSL_write() returns with success? > > Any idea? > > Kris > ______________________________**______________________________**__________ > OpenSSL Project http://www.openssl.org > User Support Mailing List openssl-users@openssl.org > Automated List Manager majord...@openssl.org > >
