Hi,
I have an SSL server handling many clients successfully using
openssl-0.9.8e. From time to time however, there are some clients that fail
to connect to it. Debugging shows that the problem happens when the client
attempts the first SSL_read, which unexpectedly returns 0.
Checking then for the SSL error shows that it has the value
SSL_ERROR_ZERO_RETURN. According to the SSL documentation this should happen
only if the SSL connection has been closed. I do know that my server is not
closing it since it is handling many other clients correctly, I also know
that for the clients facing this problem, the handshake phase is done
correctly.... it is only when the first SSL_read happens that somehow the
connection is dropped.... I have no idea why if anyone can help me.
Thanks
Here is what the documentation says about SSL_ERROR_ZERO_RETURN:
/* The TLS/SSL connection has been closed. If the protocol
version is SSL 3.0 or TLS 1.0, this result code is returned
only if a closure alert has occurred in the protocol, i.e.,
if the connection has been closed cleanly. Note that in
this case SSL_ERROR_ZERO_RETURN does not necessarily indicate
that the underlying transport has been closed. */
