On Fri, Mar 15, 2019 at 06:56:50PM +1100, David Mirabito via Linuxptp-devel wrote: > Now, I'm not sure what an "orderly shutdown" means in the context of > Multicast UDP, but it appears that zero is also returned when a UDP > packet with zero payload arrives at a PTP port, to either the > multicast address or a client's unicast address,
> I get that such broken packets probably shouldn't exist in the first > place, but since we're already robust to 1, 2, 3 .. byte payloads, it > makes sense to also survive zero byte ones. Makes sense to me. > Unfortunately there are networks (GMs?) in the wild which appear to do > this, and in not all cases do ptp client users have control over the > master. The first time we saw this an iptables rule to drop unusually > tiny frames was deemed sufficient, but it's come up again so I looked > to a more general solution. I'm not familiar with zero length mcast UDP on the PTP ports. Can you explain more about how this happens? You have seen this twice? Who is sending such traffic? > Are there situations where recvmsg could return zero to indicate an > actual "error" as opposed to "successfully received the empty string"? > I guess we could pay closer attention to errno if so. Yes, if we need to. Thanks, Richard _______________________________________________ Linuxptp-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
