Lost session on session update and ajax

[eluser]Shrike67[/eluser]
Hi all,

I have an ajax request (I use mootools Request function), all work fine and the firebug header of the response is:

Code:

Date    
Thu, 23 Apr 2009 10:20:58 GMT
Server    
Apache/2.2.3 (CentOS)
X-Powered-By    
PHP/5.1.6
Set-Cookie    
elesession=B2ANZ1Q1CWZWLFR2BjsPP1FrUjJUcANzUmQLLV0gUD4HOgNoUwsBZwNhVCZXOVRyBD9UNlJnAToKIlo2VGVUZFAxU
mMJPwRlAWBQZwcxDjYHMg1lVDUJaFZvVGYGNQ9rUW1SbVQxA2ZSOAttXWRQbwdkA2VTYgE5A2FUJlc5VHIEP1Q0UmUBOgoiWmlUIlQIUGJSYwljBHEBNlAmB3MOIwc6DS5UOwltVmNUPwYjDz9RYlI9VHwDMVIxC21dfVBvB2IDKFNlATYDNFQmVzlUcgQ
/VDRSZQE6CiJadVQhVDJQcVJYCWYEZAE2UDsHdA4jBzoNLlQ7CWlWZ1Q/BiMPQ1E0UnJUOwNsUm0LP118UGIHewM2U3QBJgN
SVG1XbFRlBGpUclImATsKIFpVVGlUd1BUUm4JaQRnATxQIgdzDiEHTw0JVCEJalZ5VDUGOg8uUTJSfFRpAyBScwsoXWlQZgd7AyR
TbwF9Az9UNVcxVDsEJ1RpUjQBcwp0Wl9UM1Q0UHdSbglxBGoBJ1AsByIOOgdyDWdUMAlsVm1UJwYwDzxRb1I4VGYDOFIzC25dZlBkB3cDPVMp
; path=/
Content-Length    
244
Connection    
close
Content-Type    
text/html; charset=UTF-8

but, when a session update is execute on the config sess_time_to_update, the session is lost and the response header is:

Code:

Date    
Thu, 23 Apr 2009 10:26:09 GMT
Server    
Apache/2.2.3 (CentOS)
X-Powered-By    
PHP/5.1.6
Set-Cookie    
elesession=a:0:{}; expires=Wed, 23-Apr-2008 20:26:09 GMT; path=/
elesession=A2QCaAFgBWpaIFNxCTRVZQU/WzsEIAFxVGIDJQp3VDoDPlA7B19cOgFjAXNTPQkvBj1SMAg9V2xUfAc4DzlRY1Y
1BWkJYlJjBGVVNAA2AGsDNgI3AWIFM1o9UzEJb1VgBTdbMQQyAWNUYQM0CmdUZAM1UGIHMVxmAWYBc1M9CS8GPVIyCD9XbFR8BzQPeVENVmQFNAljUicEM1UjAHQALQM
+AiEBbgVhWm9TOAksVWUFNls0BCwBM1Q3A2UKKlRrA2ZQewcxXGsBNgFzUz0JLwY9UjIIP1dsVHwHKA96UTdWdwUPCWZSMgQzV
T4AcwAtAz4CIQFuBWVaa1M4CSxVGQVgW3sEawFuVGsDNworVGYDf1BlByBcewFQAThTaAk4BmhSdAh8V21UfgcIDzJRclZSBTkJaVIxBDlVJwB0AC8DSwIGAXQFZlp1UzIJNVV0BWZbdQQ5ASJUdQMgCj5UYgN
/UHcHO1wgAT0BYFM1CWYGJVJvCG5XJVQqBwIPaFExVnEFOQlxUjwEIlUpACUANAN2AmgBZQVgWmFTIAk/VWYFO1sxBDYBOlQ1A2UKMlRqA3NQbgd9
; path=/
Location    
http://www.mysite.com/
Content-Length    
0
Connection    
close
Content-Type    
text/html; charset=UTF-8

in the set-cookie note the :

elesession=a:0:{}; expires=Wed, 23-Apr-2008 20:26:09 GMT; path=/

???!!!

without ajax all seems to work fine

my config:

Code:

$config['sess_cookie_name']        = 'elesession';
$config['sess_expiration']        = 7200;
$config['sess_encrypt_cookie']    = TRUE;
$config['sess_use_database']    = TRUE;
$config['sess_table_name']        = 'AUT_SESSIONS';
$config['sess_match_ip']        = FALSE;
$config['sess_match_useragent']    = TRUE;
$config['sess_time_to_update']     = 300;

Update: I try to change the session function sess_update with the test of the $_SERVER['HTTP_X_REQUESTED_WITH'] and now work fine, so the problem is really a session update with ajax problem..

Code:

function sess_update()
    {
        // We only update the session every five minutes by default
        if ((($this->userdata['last_activity'] + $this->sess_time_to_update) >= $this->now) || (isset($_SERVER['HTTP_X_REQUESTED_WITH']) && ($_SERVER['HTTP_X_REQUESTED_WITH'] == 'XMLHttpRequest')))
        {
            return;
        }

any help please?