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Only increase max_successful_tryno when we have a positive response to a probe;

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i.e., the probe didn't just time out. This was the case before r11253 when I
mistakenly removed it. I meant only to allow ultrascan_adjust_timing to be
called when rcvdtime == NULL, but as a side effect I also allowed
max_successful_tryno to increase in that case too. I was able to get that bit
of code to run with rcvdtime == NULL in a normal scan, but I don't think it
happens often.

I also improved the comments in that block of code.
This commit is contained in:
david
2008-12-23 02:29:04 +00:00
parent 8eb6313aa2
commit a246aaf469
1 changed files with 10 additions and 10 deletions
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20
scan_engine.cc
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@@ -2653,18 +2653,18 @@ static void ultrascan_port_probe_update(UltraScanInfo *USI, HostScanStats *hss,
ultrascan_adjust_timeouts(USI, hss, probe, rcvdtime);
if (adjust_timing &&
/* If we are not in "noresp_open_scan" and got something back and the
* newstate is PORT_FILTERED then we got ICMP error response.
* ICMP errors are often rate-limited (RFC1812) and/or generated by
* middle-box. No reason to slow down the scan. */
/* We try to defeat ratelimit only when -T4 or -T5 is used */
/* We only care ICMP errors timing when we get them during first probe to a port */
/* If we got a response that meant "filtered", then it was an ICMP error.
These are often rate-limited (RFC 1812) or generated by a different
host. At -T4 and above we consider only the first such response
(probe->tryno == 0) for timing purposes and ignore the rest. */
((changed && newstate != PORT_FILTERED) || USI->noresp_open_scan || probe->tryno == 0 || o.timing_level < 4) &&
/* If we are in --defeat-rst-ratelimit mode, we do not care whether we got RST back or not
* because RST and "no response" both mean PORT_CLOSEDFILTERED. Do not slow down */
!(o.defeat_rst_ratelimit && newstate == PORT_CLOSEDFILTERED && probe->tryno > 0)) { /* rcvdtime is interesting */
/* Do not slow down if we are in --defeat-rst-ratelimit mode and the new
state is closed|filtered. We don't care if it's closed|filtered because
of a RST or a timeout because they both mean the same thing. */
!(o.defeat_rst_ratelimit && newstate == PORT_CLOSEDFILTERED && probe->tryno > 0)) {
ultrascan_adjust_timing(USI, hss, probe, rcvdtime);
if (probe->tryno > hss->max_successful_tryno) {
if (rcvdtime != NULL && probe->tryno > hss->max_successful_tryno) {
/* We got a positive response to a higher tryno than we've seen so far. */
hss->max_successful_tryno = probe->tryno;
if (o.debugging)
log_write(LOG_STDOUT, "Increased max_successful_tryno for %s to %d (packet drop)\n", hss->target->targetipstr(), hss->max_successful_tryno);