Handling Non-Blocking I/O Errors in OpenSSL

SSL_accept()

After result of:	Select on:	Try this next:
<0, SSL_ERROR_WANT_READ	R	SSL_accept()
<0, SSL_ERROR_WANT_WRITE	W	SSL_accept()
0, SSL_ERROR_SYSCALL		nothing (illegal EOF)
<0, SSL_ERROR_SYSCALL		see errno

SSL_connect()

After result of:	Select on:	Try this next:
<0, SSL_ERROR_WANT_READ	R	SSL_connect()
<0, SSL_ERROR_WANT_WRITE	W	SSL_connect()
0, SSL_ERROR_SYSCALL		nothing (illegal EOF)
<0, SSL_ERROR_SYSCALL		see errno

SSL_read()

After result of:	Select on:	Try this next:
<0, SSL_ERROR_WANT_READ	R	SSL_read()
<0, SSL_ERROR_WANT_WRITE	W	SSL_read()
0, SSL_ERROR_ZERO_RETURN		nothing (socket is shut down)

SSL_write()

After result of:	Select on:	Try this next:
<0, SSL_ERROR_WANT_READ	R	SSL_write()
<0, SSL_ERROR_WANT_WRITE	W	SSL_write()
0, SSL_ERROR_ZERO_RETURN		nothing (socket is shut down)

SSL_shutdown()

After result of:	Select on:	Try this next:
-1, SSL_ERROR_WANT_READ	R	SSL_shutdown()
-1, SSL_ERROR_WANT_WRITE	W	SSL_shutdown()
0	R	SSL_shutdown()