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POHow to use openSSL with memory BIOs and non blocking sockets
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copied!<p>I'm new to openSSL and I trying to figure out what the best / good solution is to create a https connection when using non blocking sockets, and libraries such as libevent, libev or libuv in combination with memory BIOs. </p> <p>I'm trying to figure out how to manage openSSL calls/data and application data. In short my understanding of how a ssl client application should work is something like this:</p> <ul> <li>create SSL_CTX</li> <li>create a new socket connection (e.g. I'm using libuv)</li> <li>create two memory BIOs: <ul> <li>one is filled with data I receive from the server (readBio)</li> <li>the other one is used to in the application code to read from. (writeBio)</li> </ul></li> <li>create a SSL* and set state to SSL_connect_state</li> <li>start the handshake process with SSL_do_handshake</li> <li>[loop] receive / send data </li> </ul> <p>As I'm using libuv (but this could be any other async/non-blocking library), I have a <em>read</em> callback that gets called when data is received on the socket. When I have data which must be written to the socket, I pass this data into a <em>write</em> function of the library (in this <code>uv_write()</code>), but in between this I need to put the calls to SSL.</p> <p>So after calling SSL_do_handshake(...), SSL stores some data into the writeBIO which I must read and pass into the socket. One question I was thinking about, how do I know that SSL stores data into this BIO, and secondly how do I know when I should send this over the socket.</p> <p>After looking at some code, I figured out that I had to consume from the writeBIO after calling SSL_do_handshake(). But the next steps are not clear to me. After s ending the first bytes from the handshake the 'event' loop of libuv sets everything in motion; when new data arrives on the socket my '<code>onread()</code> callback is called. But how do I handle this incoming data? (e.g. do I keep SSL state myself (<-- something which some people have advised me <em>not</em> do to)).</p> <p>Although I've seen lots of examples which use blocking sockets and the core SSL functions to make a connection I haven't found a good clean/minimalistic example which shows how to use memory BIOs as a client. </p> <p>I've pasted some code I'm using to test openSSL here: <a href="https://gist.github.com/3989091" rel="noreferrer">https://gist.github.com/3989091</a></p> <p>Someone around who can describe the process of using async/non-blocking sockets and memory BIOs with SSL? </p> <p>Thanks R</p>

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