RE: radiusclient thread-safety

28 Feb 2010

      Hi Alan,

Thank you for reply.
I tested it now with rc_handle per thread but the problem still persists. Even if I protect all calls to libradius with mutex:

pthread_mutex_lock(&mp);
rc_init_handle();
[build send avpair here]
rc_auth();
rc_free_handle();
pthread_mutex_unlock(&mp);

Looks like memory corruption, because if I don't leave thread to leave for a long time, the problem disappears. Probably if thread exits it cleans up stack (or maybe because this way there're no 2 concurrent threads that ran through rc_auth() ).

So I compiled it with -fstack-protector-all, but it didn't fixed the problem.

Here's what I did, in lib/sendserver.c in rc_send_server() I added break, to disable exiting with TIMEOUT_RC, like following:

                if (FD_ISSET (sockfd, &readfds))
                        break;

                /*
                 * Timed out waiting for response.  Retry "retry_max" times
                 * before giving up.  If retry_max = 0, don't retry at all.
                 */
                if (++retries >= retry_max)
                {
                        break;   // ########################################## HERE #######################
                        rc_log(LOG_ERR,
                                "rc_send_server: no reply from RADIUS server");
                        close (sockfd);
                        memset (secret, '\0', sizeof (secret));
                        return TIMEOUT_RC;
                }

And magically it fixed the issue.

That's beyond of my understanding, but looks like 
if (FD_ISSET (sockfd, &readfds))
                        break;

misbehaves (or gets corrupted).

Only rare I get "rc_send_server: select: Bad file descriptor".

What do you think please?
...
-----Original Message-----
From: freeradius-devel-bounces+alex=jajah.com@lists.freeradius.org
[mailto:freeradius-devel-bounces+alex=jajah.com@lists.freeradius.org]
On Behalf Of Alan DeKok
Sent: יום ו 26 פברואר 2010 17:51
To: FreeRadius developers mailing list
Subject: Re: radiusclient thread-safety
Alex Massover wrote:
...
Hello,
I'm using radiusclient lib from multithreaded application, by having
a "static rc_handle *rh" and calling rc_auth() from different threads.
It's not thread-safe.  There are no mutex locks in the code.
...
Can someone enlighten me on the subj please?
Use one rc_handle per child thread.
The code needs pretty significant changes to make it thread-safe.
Alan DeKok.
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