[stunnel-users] stunnel-4.20 server loop on AIX 5.3

Michal Trojnara Michal.Trojnara at mobi-com.net
Thu May 31 20:46:28 CEST 2007

On Monday 28 May 2007 20:51, Peter Heimann wrote:
> Under heavy usage, stunnel-4.20 on AIX 5.3 enters into a loop with high
> CPU load.
> SSL_accept() returns with error, SSL_get_error() returns 5
> (SSL_ERROR_SYSCALL). get_last_socket_error() returns EAGAIN, and the loop
> continues without end. Nevertheless, new connection requests still get
> processed.
> Even before CPU usage goes up, for every new connection, SSL_accept()
> results in SSL_ERROR_SYSCALL for 20 to 1800 times before finally
> data is exchanged.
> What might trigger this loop on AIX 5.3? How can it be avoided?

First of all your email is a perfect problem report.
A dream of a software maintainer.  8-)  Thank you!

I found benchmarking tools to be able to reveal some
OpenSSL bugs that are extremely rare in real world.

Could it be the problem described at the end of this page:
? I have found similar pages for other OpenSSL applications.

An alternative workaround would be changing:

Please let us know about results of your tests.

Best regards,
	Michał Trojnara
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