gethostbyname() being not thead-safe is a well know problem, most (all ?) implementations of this function use static storage.
Alternative is gethostbyname_r(), but it's really not portable, freebsd doesn't support gethostbyname_r as far as I know.
Furthermore, getaddrinfo() is supposed to be thread-safe, but if I remember correctly, previous version of freebsd (4.x ?) used a non thread-safe getaddrinfo() implementation.
IMHO, the best way to use gethostbyname() call is protect it with some lock mecanism:
LOCK(); hp = gethostbyname(...); [...] UNLOCK();
Bye.
Meadele Mathieu.
Gary McKinney wrote:
OK - I FINALLY found something on the gethostbyname() function not being thread safe....
http://lists.freebsd.org/pipermail/freebsd-threads/2004-February/001645.html
According to the info I read the gethostbyname() function uses static storage so if it is called in a threaded environment it is possible (and most likely probable) the information would be overwritten by a second call by another thread before it was read back out by the calling thread - the message goes on to say there *IS* a thread safe re-entrant function ( getaddrinfo() function) which should be used in a threaded environment to alleviate the "problem"...
I realize this is probably not the answer people are wanting to see (it would require some changes to the autoconf scripts to take into account FreeBSD vs other os types) but apparently that is the tack the FreeBSD community took to fix this problem...
Gary N. McKinney
Network Administrator Computer Services Dept. Brevard County Library System
---------- Original Message ---------------------------------- From: [EMAIL PROTECTED] (Paul Hampson) Reply-To: [EMAIL PROTECTED] Date: Thu, 22 Apr 2004 02:06:02 +1000
On Wed, Apr 21, 2004 at 08:49:47AM -0400, Gary McKinney wrote:
I realize this is not a direct FreeRadius issue but possibly could be indirectly related if the actual problem still exists with thread locking...
I checked the FreeBSD site for any PR listings for what you have described... did not find
anything - have you checked against the latest release of FreeBSD for the problem???
http://lists.cistron.nl/archives/freeradius-users/2003/09/frm00212.html * http://lists.cistron.nl/archives/freeradius-users/2003/09/msg00212.html http://lists.cistron.nl/archives/freeradius-users/2003/09/frm00434.html http://lists.cistron.nl/archives/freeradius-devel/2003/09/frm00093.html
_I_ haven't tested against the lastest release of FreeBSD. I'd welcome any improvements to the thread-safety of FreeRADIUS, so if you want to test it out and suggest changes that don't break any other versions of FreeBSD, any other BSD flavours, and (if possible) Tru64 and OS/X...
However, given that we're ramping up to a release, I'd rather not duplicate the 0.9 series's tendancy to need autoconf fixes for gethostby* immediately after _each_ release. If we have something safe- looking before we start the pre release cycle, and it gets _tested_ by various FreeBSD and other bodies, then maybe. :-)
Whoops. While trawling the list archives from September I found someone who asked me a question, and I never answered. :-( I hope he found enlightenment eventually, and didn't leave us for Radiator.
-- Paul "TBBle" Hampson, on an alternate email client.
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