K 10
svn:author
V 7
asomers
K 8
svn:date
V 27
2019-09-11T18:54:45.652617Z
K 7
svn:log
V 556
ping: Verify whether a datagram timestamp was actually received.

ping(8) uses SO_TIMESTAMP, which attaches a timestamp to each IP datagram at
the time it's received by the kernel.  Except that occasionally it doesn't.
Add a check to see whether such a timestamp was actually set before trying
to read it.  This fixes segfaults that can happen when the kernel doesn't
attach a timestamp.

The bug has always existed, but prior to r351461 it manifested as an
implausible round-trip-time, not a segfault.

Reported by:	pho
MFC after:	3 days
MFC-With:	351461

END