happens when a host was scanned in the A scan but wasn't scanned in the B scan.
I previously had it ignore such changes using the logic that the diff should be
like scan aggregation: no new information means no state change. But I think
it's more useful to see those changes in which hosts were scanned.
This is analogous to r10263, which did the same thing for port state changes.
increases the scan dealy with an increase in max_successful_tryno. When I
reverted a bunch of changes in r11651, I removed the moved code, leaving the
scan delay increase nowhere. This puts it back in ultrascan_port_probe_update
where it was before.
Don't make a host the global ping host until it moves to the completed
hosts list, and only change the global ping probe if the new probe is no
worse than the old (according to pingprobe_is_better).
Restore the ping magnifier for host congestion window updates.
Ignore the timing of certain ICMP errors that are likely to be rate
limited and don't change the port or host state. Avoid making timing
pings out of probes that elicit such errors. This used to be done only
for port scans and only at -T4 and above (and didn't prohibit the
creation of timing pings). Now it is done for host discovery too, and at
all timing levels.
Gracefully handle updates from the recent past in RateMeter. Doesn't
affect performance, but avoids a rare assertion failure.
script event: start, finish, timeout, and error. The file name is now stored as
a std::string in struct thread_record so we have it when we don't have access
to the thread's environment.
num_probes_active == 0 in HostScanStats::completed. The reason for this is
fairly subtle and I didn't realize it at first: We have to make sure there are
no active probes because once in the completed list, probes don't time out.
Probes that are active stay active in the count. If the congestion window ever
falls below the number of these active probes, the program will hang waiting
for them to time out.
We could get away with this in the case of up hosts, because we call
HostScanStats::destroyAllOutstandingProbes in that case. We could do that in
the down case too, but that would prohibit a down host from being found up
later on. That's currently a matter of some luck; we don't keep sending probes
after a host is down but will accept replies to any other probes that have
already been sent.
source address didn't match the target address. Fyodor correctly pointed out
that this is wrong for UDP scans, when we need to slow down for a firewall
sending unreachables to know which probes don't elicit one. I'm going to try
something a little different in nmap-perf.
