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Add zeek::max_random() & fix misuse of RAND_MAX w/ zeek::random_number()

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In deterministic mode, RAND_MAX is not related to the result of
zeek::random_number() (formerly bro_random()), but some logic was
using RAND_MAX as indication of the possible range of values.  The
new zeek::max_random() will give the correct upper-bound regardless
of whether deterministic-mode is used.
This commit is contained in:
Jon Siwek 2020-07-22 09:57:56 -07:00
parent bde38893ce
commit d486af06b1
6 changed files with 24 additions and 9 deletions
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10
src/PacketFilter.cc
View file

@ -18,7 +18,7 @@ void PacketFilter::AddSrc(const IPAddr& src, uint32_t tcp_flags, double probabil
{
Filter* f = new Filter;
f->tcp_flags = tcp_flags;
f->probability = uint32_t(probability * RAND_MAX);
f->probability = probability * static_cast<double>(zeek::max_random());
auto prev = static_cast<Filter*>(src_filter.Insert(src, 128, f));
delete prev;
}
@ -27,7 +27,7 @@ void PacketFilter::AddSrc(zeek::Val* src, uint32_t tcp_flags, double probability
{
Filter* f = new Filter;
f->tcp_flags = tcp_flags;
f->probability = uint32_t(probability * RAND_MAX);
f->probability = probability * static_cast<double>(zeek::max_random());
auto prev = static_cast<Filter*>(src_filter.Insert(src, f));
delete prev;
}
@ -36,7 +36,7 @@ void PacketFilter::AddDst(const IPAddr& dst, uint32_t tcp_flags, double probabil
{
Filter* f = new Filter;
f->tcp_flags = tcp_flags;
f->probability = uint32_t(probability * RAND_MAX);
f->probability = probability * static_cast<double>(zeek::max_random());
auto prev = static_cast<Filter*>(dst_filter.Insert(dst, 128, f));
delete prev;
}
@ -45,7 +45,7 @@ void PacketFilter::AddDst(zeek::Val* dst, uint32_t tcp_flags, double probability
{
Filter* f = new Filter;
f->tcp_flags = tcp_flags;
f->probability = uint32_t(probability * RAND_MAX);
f->probability = probability * static_cast<double>(zeek::max_random());
auto prev = static_cast<Filter*>(dst_filter.Insert(dst, f));
delete prev;
}
@ -113,5 +113,5 @@ bool PacketFilter::MatchFilter(const Filter& f, const IP_Hdr& ip,
return false;
}
return uint32_t(zeek::random_number()) < f.probability;
return zeek::random_number() < f.probability;
}