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RateMeter::update() used to abort if the new time was earlier than the old time. But on my SMP Linux 2.6.20 system, I've been doing large-scale scanning and I'm getting very occasional values like "now=1214173867.8027; last_update_tv=1214173867.8065". Unless I'm missing something, I think my gettimeofday may have decreased by 38 microseconds. Perhaps due to SMP and the old kernel. Anyway, I changed it so that decreases of up to 1 millisecond just give a warning (one-time) rather than abort Nmap.

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fyodor
2008-06-23 00:56:49 +00:00
parent 726febac7c
commit a1c363b84a
1 changed files with 15 additions and 0 deletions
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15
timing.cc
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@@ -312,6 +312,7 @@ double RateMeter::getCurrentByteRate(const struct timeval *now, bool update) {
received rather than calling gettimeofday. */
void RateMeter::update(u32 packets, u32 bytes, const struct timeval *now) {
struct timeval tv;
static int clockwarn = 0;
double diff;
double interval;
double count;
@@ -336,6 +337,20 @@ void RateMeter::update(u32 packets, u32 bytes, const struct timeval *now) {
/* How long since the last update? */
diff = TIMEVAL_SUBTRACT(*now, last_update_tv) / 1000000.0;
/* On my SMP Linux 2.6.20 system, I'm getting very occasional values
like "now=1214173867.8027; last_update_tv=1214173867.8065".
Unless I'm missing something, I think my gettimeofday may have
decreased by 38 microseconds. Perhaps due to SMP and the old
kernel. Anyway, I think I'll just treat decreases of up to 1ms
as zero -Fyodor */
if (diff < 0 && diff > -0.001) {
if (!clockwarn) {
error("Warning: RateMeter::update: negative time delta; now=%lu.%lu; last_update_tv=%lu.%lu", (unsigned long) now->tv_sec, (unsigned long) now->tv_usec, (unsigned long) last_update_tv.tv_sec, (unsigned long) last_update_tv.tv_usec);
clockwarn = 1;
}
diff = 0.0;
}
if (diff < 0.0)
fatal("RateMeter::update: negative time delta; now=%lu.%lu; last_update_tv=%lu.%lu", (unsigned long) now->tv_sec, (unsigned long) now->tv_usec, (unsigned long) last_update_tv.tv_sec, (unsigned long) last_update_tv.tv_usec);