[distcache-users] A defect in distcache 1.5.1

[Priit R. <pri...@se...>]

    Hello,

While writing  a squid authentication module (pin-calc with limited 
lifetime one-time passwords) which supports sharing user authentication 
status
within squid cluster (using distcache, of course ;-)) I found out that 
when I created distcache sessions with timeout of 10 hours,
these sessions would be removed by dc_server in 1640 seconds instead. I 
took a look at the source and spotted following problem in distcache 1.5.1
libsys/sys.c:
---------------------------
int SYS_expirycheck(const struct timeval *timeitem, unsigned long 
msec_expiry,
                const struct timeval *timenow)
{
        struct timeval threshold;
        unsigned long usec_expiry = msec_expiry * 1000;               
<-------------- When using timeouts long enough (>4294 seconds), this 
will overflow.
        SYS_memcpy(struct timeval, &threshold, timeitem);
        threshold.tv_sec = threshold.tv_sec + (usec_expiry / 1000000L);
        threshold.tv_usec += (usec_expiry % 1000000);
        if(threshold.tv_usec > 1000000) {
                threshold.tv_usec -= 1000000;
                threshold.tv_sec++;
        }
        if(timercmp(timenow, &threshold, <))
                return 0;
        return 1;
}
--------------------------------

Maybe this function should look something like this instead?

int SYS_expirycheck(const struct timeval *timeitem, unsigned long 
msec_expiry,
                const struct timeval *timenow)
{
        struct timeval threshold;
        SYS_memcpy(struct timeval, &threshold, timeitem);
        threshold.tv_sec = threshold.tv_sec + (msec_expiry / 1000);
        threshold.tv_usec += (msec_expiry % 1000) * 1000;
        if(threshold.tv_usec > 1000000) {
                threshold.tv_usec -= 1000000;
                threshold.tv_sec++;
        }
        if(timercmp(timenow, &threshold, <))
                /* Not expired yet */
                return 0;
        /* Expired */
        return 1;
}

Regards,
Priit