Only do a kernel call with good reason.

Also, re-attempt to receive for throughput.

Return more specific error status.

Calling poll invalidates all pointers. Don't cache them!

==> discovered we used the wrong structure for fdes.

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test for memory leaks
test tcp or udp

Records with only writes are not copied into the reply.
If that record was the last record in a cycle, you lose the cycle termination.
This catches this uncommon, but deadly, case.

We only use 'device' when passive is set.

Prepare to test also sub-word accesses.

  => more formats will match.