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mutual_pattern.cpp
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mutual_pattern.cpp
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#include "mutual_pattern.h"
#include <numeric>
using namespace std;
MutualPattern::MutualPattern(ByteArr& a, ByteArr& b) {
is_mutual_.resize(a.size(), true);
mutual_till_ = a.size();
size_mutual_ = a.size();
size_mutual_half_ = a.size() / 2;
data_ = a;
intersectBuf(b);
}
bool MutualPattern::intersectBufIf(const ByteArr& other, bool do_cnt) {
cnt_all_ += do_cnt;
auto mutual_len = intersectLen(other);
if (mutual_len && mutual_len < size_mutual_) {
intersectBuf(other);
cnt_ += do_cnt;
return true;
}
else if (mutual_len == size_mutual_)
cnt_ += do_cnt;
return false;
}
void MutualPattern::intersectBuf(const ByteArr& other) {
uint first_mutual = numeric_limits<uint>::max();
uint last_mutual = first_mutual;
for (uint i=first_mutual_; i < mutual_till_; i++) {
if (!is_mutual_[i]) continue;
if (data_[i] != other[i]) {
data_[i] = 63;
is_mutual_[i] = false;
size_mutual_--;
if (i >= data_.size() / 2) size_mutual_half_--;
} else {
first_mutual = min(first_mutual, i);
last_mutual = i;
}
}
first_mutual_ = first_mutual;
mutual_till_ = last_mutual+1;
}
uint MutualPattern::intersectLen(const ByteArr& other) {
return intersectLen(&other[0]);
}
uint MutualPattern::intersectLen(const uchar* other) {
uint sum = 0;
// cout << first_mutual_ << ' ' << last_mutual_ << '\n';
for (uint i=first_mutual_; i < mutual_till_; i++) {
if (!is_mutual_[i]) continue;
if (data_[i] == other[i]) sum++;
}
return sum;
}
uint MutualPattern::intersectLenHalf(const uchar* other) {
uint start_idx = data_.size() / 2, sum = 0;
for (uint i=start_idx; i < mutual_till_; i++) {
if (!is_mutual_[i]) continue;
if (data_[i] == other[i-start_idx]) sum++;
}
return sum;
}
bool MutualPattern::doesMatch(const uchar* buf) {
return intersectLen(buf) == size_mutual_;
}
bool MutualPattern::doesMatchHalf(const uchar* buf) {
// auto r = intersectLenHalf(buf);
// cout << r << " == " << size_mutual_ << '\n';
return intersectLenHalf(buf) == size_mutual_half_;
}
bool MutualPattern::doesMatchApprox(const uchar* buf) {
vector<uchar> mutual;
for (uint i=first_mutual_; i < mutual_till_; i++) {
if (!is_mutual_[i]) continue;
if (data_[i] == buf[i]) mutual.emplace_back(data_[i]);
}
if (mutual.size() == size_mutual_) return true;
if ((double) mutual.size() / size_mutual_ < 0.79) return false;
return calcEntropy(mutual) > 0.75;
}
bool MutualPattern::hasPattern(int off, const ByteArr& buf) {
for (uint i=0; i < buf.size(); i++) {
if (!is_mutual_[i]) return false;
if (data_[off+i] != buf[i]) return false;
}
return true;
}
vector<uchar> MutualPattern::getDistinct() const {
vector<uchar> r;
for (uint i=first_mutual_; i < mutual_till_; i++) {
if (!is_mutual_[i]) continue;
r.emplace_back(data_[i]);
}
return r;
}
double MutualPattern::successRate() {
return (double)cnt_ / cnt_all_;
}
std::ostream& operator<<(std::ostream& out, const MutualPattern& mp) {
for (uint i=0; i < mp.data_.size(); i++) {
if (i % 4 == 0) out << ' ';
out << (mp.is_mutual_[i]? mkHexStr(&mp.data_[i], 1) : "__");
}
return out;
}
bool operator==(const MutualPattern& a, const MutualPattern& b) {
for (uint i=0; i < a.data_.size(); i++)
if (a.data_[i] != b.data_[i]) return false;
return true;
}
bool operator!=(const MutualPattern& a, const MutualPattern& b) {
return !(a == b);
}
// utility functions
patterns_t genRawPatterns(buffs_t buffs) {
patterns_t patterns;
auto gen = getRandomGenerator();
auto dis = uniform_int_distribution<size_t>(0, buffs.size()-1);
shuffle(buffs.begin(), buffs.end(), gen);
if (buffs.size() == 1) {
auto a = buffs[0];
patterns.emplace_back(MutualPattern(a, a));
}
for (uint i=0; i+1 < buffs.size(); i++) {
auto a = buffs[i], b = buffs[i+1];
auto p = MutualPattern(a, b);
if (!p.size_mutual_) continue;
for (int n=4; n; n--) { // remove (some) noise
uint idx = dis(gen);
p.intersectBufIf(buffs[idx]);
}
if (!contains(patterns, p))
patterns.emplace_back(p);
}
return patterns;
}
/* also further intersects patterns as needed */
void countPatternsSuccess(patterns_t& patterns, buffs_t buffs) {
for (auto& buff : buffs) {
for (auto it = patterns.begin(); it != patterns.end();)
if (it->intersectBufIf(buff, true) && count(patterns.begin(), patterns.end(), *it) > 1)
it = patterns.erase(it);
else it++;
}
}
void filterBySuccessRate(patterns_t& patterns, const string& label) {
double total_p = 0;
for (auto it = patterns.begin(); it != patterns.end();) {
auto p = it->successRate();
if (p < 0.2) patterns.erase(it);
else {
it++;
total_p += p;
}
}
if (total_p > 1.001) { // probably just random noise
logg(V, "ignoring all ", patterns.size(), " patterns for ", label, ".. they overlap too much (", total_p, ")\n");
patterns.clear();
}
if (total_p < 0.8 && patterns.size()) { // probably just random noise
logg(V, "ignoring all ", patterns.size(), " patterns for ", label, ".. total_p=", total_p, " too small\n");
patterns.clear();
}
}