length != BPF_WORDALIGN(length)
This meeans that it is possible for this to be true:
interface->rbuf_offset > interface->rbuf_len
Handle this case in the test for running out of packets. While
OpenBSD's solution of setting interface->rbuf_len to
BPF_WORDALIGN(length) is safe due to the size of the buffer, I think
this solution results in less hidden assumptions.
This should fix the problem of dhclient running away and consuming 100%
CPU.
PR: bin/102226
Submitted by: Joost Bekkers <joost at jodocus.org>
MFC after: 3 days
ebe609b4a2