ModSecurity/src/operators/fuzzy_hash.cc
2017-11-13 23:54:30 -03:00

127 lines
3.2 KiB
C++

/*
* ModSecurity, http://www.modsecurity.org/
* Copyright (c) 2015 Trustwave Holdings, Inc. (http://www.trustwave.com/)
*
* You may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* If any of the files related to licensing are missing or if you have any
* other questions related to licensing please contact Trustwave Holdings, Inc.
* directly using the email address security@modsecurity.org.
*
*/
#include "src/operators/fuzzy_hash.h"
#include <string>
#include "src/operators/operator.h"
#include "src/macro_expansion.h"
#include "src/utils/system.h"
namespace modsecurity {
namespace operators {
bool FuzzyHash::init(const std::string &param2, std::string *error) {
#ifdef WITH_SSDEEP
std::string digit;
std::string file;
std::istream *iss;
struct fuzzy_hash_chunk *chunk, *t;
std::string err;
auto pos = m_param.find_last_of(' ');
if (pos == std::string::npos) {
error->assign("Please use @fuzzyHash with filename and value");
return false;
}
digit.append(std::string(m_param, pos+1));
file.append(std::string(m_param, 0, pos));
try {
m_threshold = std::stoi(digit);
} catch (...) {
error->assign("Expecting a digit, got: " + digit);
return false;
}
std::string resource = utils::find_resource(file, param2, &err);
iss = new std::ifstream(resource, std::ios::in);
if (((std::ifstream *)iss)->is_open() == false) {
error->assign("Failed to open file: " + m_param + ". " + err);
delete iss;
return false;
}
for (std::string line; std::getline(*iss, line); ) {
chunk = (struct fuzzy_hash_chunk *)calloc(1,
sizeof(struct fuzzy_hash_chunk));
chunk->data = strdup(line.c_str());
chunk->next = NULL;
if (m_head == NULL) {
m_head = chunk;
} else {
t = m_head;
while (t->next) {
t = t->next;
}
t->next = chunk;
}
}
delete iss;
return true;
#else
error->assign("@fuzzyHash: SSDEEP support was not enabled " \
"during the compilation.");
return false;
#endif
}
FuzzyHash::~FuzzyHash() {
struct fuzzy_hash_chunk *c = m_head;
while (c) {
struct fuzzy_hash_chunk *t = c;
free(c->data);
c->data = NULL;
c = c->next;
free (t);
}
m_head = NULL;
}
bool FuzzyHash::evaluate(Transaction *t, const std::string &str) {
#ifdef WITH_SSDEEP
char result[FUZZY_MAX_RESULT];
struct fuzzy_hash_chunk *chunk = m_head;
if (fuzzy_hash_buf((const unsigned char*)str.c_str(),
str.size(), result)) {
t->debug(4, "Problems generating fuzzy hash");
return false;
}
while (chunk != NULL) {
int i = fuzzy_compare(chunk->data, result);
if (i >= m_threshold) {
t->debug(4, "Fuzzy hash: matched " \
"with score: " + std::to_string(i) + ".");
return true;
}
chunk = chunk->next;
}
#endif
/* No match. */
return false;
}
} // namespace operators
} // namespace modsecurity