ping counter overflow
Gerald Heinig
gheinig at syskonnect.de
Mon Dec 6 06:32:22 PST 2004
Hi all,
I've run into a possible bug in ping(8) while investigating a strange
duplicate packet effect in our driver.
The effect shows up on other drivers and I believe it's due to a counter
overflow in ping.
Basically, leave ping -f on a gigabit link for a few days (for medium to
large values of "a few", ie. at least 3 or 4). Stop the ping and get
lots of duplicate packets.
I changed the 5 counter variables (nmissedmax, npackets, nreceived,
nrepeats, ntransmitted) to short (from long) to reduce the time taken to
overflow and managed to get the effect very easily - it takes about 3
seconds on a gigabit link.
Changing these variables to their unsigned counterparts solved the problem.
My question: shouldn't these counters be unsigned? (ie. unsigned long,
instead of long)
Regards,
Gerald
More information about the freebsd-net
mailing list