OpenSSL and multithreaded programs

[Chris Dodd]

Is the OpenSSL library supposed to be at all reentrant? I've had odd
problems (intermittent errors) when trying to use OpenSSL in a multithreaded
program (multiple threads each dealing with independent SSL connections),
and have apparently solved them by creating a single global mutex and
wrapping a mutex acquire around every call into the library. Is
this kind of locking expected to be needed?

Chris Dodd
cd...@csl.sri.com

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[Jeremy Farrell]

> From: Chris Dodd

>
> Is the OpenSSL library supposed to be at all reentrant? I've had odd
> problems (intermittent errors) when trying to use OpenSSL in
> a multithreaded
> program (multiple threads each dealing with independent SSL
> connections),
> and have apparently solved them by creating a single global mutex and
> wrapping a mutex acquire around every call into the library. Is
> this kind of locking expected to be needed?

http://lmgtfy.com/?q=openssl+locking______________________________________________________________________

[David Schwartz]

On 5/5/2011 10:01 AM, Chris Dodd wrote:

> Is the OpenSSL library supposed to be at all reentrant? I've had odd
> problems (intermittent errors) when trying to use OpenSSL in a
> multithreaded
> program (multiple threads each dealing with independent SSL connections),
> and have apparently solved them by creating a single global mutex and
> wrapping a mutex acquire around every call into the library. Is
> this kind of locking expected to be needed?

This should not be needed so long as you follow two rules:

1) You must properly set the multi-threaded locking callback.

2) You must not attempt to access the same object directly from two
threads at the same time. For example, you cannot call SSL_read and
SSL_write concurrently on the same SSL object.

DS

[dave.m...@emc.com]

We use OpenSSL in a highly multi-threaded application and don't have problems. There are some locking callbacks that you should be using. Look up these:

CRYPTO_set_id_callback();
CRYPTO_set_locking_callback();
CRYPTO_set_dynlock_create_callback();
CRYPTO_set_dynlock_lock_callback();
CRYPTO_set_dynlock_destroy_callback();

Dave.

-----Original Message-----
From: owner-ope...@openssl.org [mailto:owner-ope...@openssl.org] On Behalf Of Chris Dodd
Sent: Thursday, May 05, 2011 1:01 PM
To: openss...@openssl.org
Subject: OpenSSL and multithreaded programs

Is the OpenSSL library supposed to be at all reentrant? I've had odd
problems (intermittent errors) when trying to use OpenSSL in a multithreaded
program (multiple threads each dealing with independent SSL connections),
and have apparently solved them by creating a single global mutex and
wrapping a mutex acquire around every call into the library. Is
this kind of locking expected to be needed?

Chris Dodd
cd...@csl.sri.com