Testing has shown that when a timeout < 1000ms is specified the
IcmpSendEcho calls fail (apparently) randomly. Once the timeout is
1000ms or greater it works as expected. Therefore I've updated the fix
to use 1000ms as a minimum. The existing logic ensures that the ttl is
less than the specified timeout in any case:
http://cr.openjdk.java.net/~robm/8143397/webrev.02/
-Rob
On 01/12/15 14:59, Rob McKenna wrote:
It appears that there is an undocumented minimum timeout in the
IcmpSendEcho* functions. If the timeout parameter is set to a number
below this minimum timeout it is effectively ignored. Thus if you wanted
to ensure that you could ping a particular host within a certain timeout
less than the undocumented minimum, you could potentially receive a
false positive. (i.e. if you set the timeout to 20ms but the ping takes
30ms, IcmpSendEcho will still succeed)
The following fix checks the icmp reply packet and compares the round
trip time to the requested timeout parameter before deciding whether the
call was successful or not:
http://cr.openjdk.java.net/~robm/8143397/webrev.01/
-Rob
