/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mutators.h"
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <random>
#include <vector>
#include "tls_parser.h"
// Helper class to simplify TLS record manipulation.
class Record {
public:
static std::unique_ptr<Record> Create(
const uint8_t *data, size_t size,
size_t remaining) {
return std::unique_ptr<Record>(
new Record(data, size, remaining));
}
void insert_before(
const std::unique_ptr<Record> &other) {
assert(data_ && size_ > 0);
// Copy data in case other == this.
std::vector<uint8_t> buf(size_);
memcpy(buf.data(), data_, size_);
uint8_t *dest =
const_cast<uint8_t *>(other->data());
// Make room for the record we want to insert.
memmove(dest + size_, other->data(), other->size() + other->remaining());
// Insert the record.
memcpy(dest, buf.data(), size_);
}
void truncate(size_t length) {
assert(length >= 5 + EXTRA_HEADER_BYTES);
uint8_t *dest =
const_cast<uint8_t *>(data_);
size_t l = length - (5 + EXTRA_HEADER_BYTES);
dest[3] = (l >> 8) & 0xff;
dest[4] = l & 0xff;
memmove(dest + length, data_ + size_, remaining_);
}
void drop() {
uint8_t *dest =
const_cast<uint8_t *>(data_);
memmove(dest, data_ + size_, remaining_);
}
const uint8_t *data() {
return data_; }
size_t remaining() {
return remaining_; }
size_t size() {
return size_; }
private:
Record(
const uint8_t *data, size_t size, size_t remaining)
: data_(data), remaining_(remaining), size_(size) {}
const uint8_t *data_;
size_t remaining_;
size_t size_;
};
// Parse records contained in a given TLS transcript.
std::vector<std::unique_ptr<Record>> ParseRecords(
const uint8_t *data,
size_t size) {
std::vector<std::unique_ptr<Record>> records;
nss_test::TlsParser parser(data, size);
while (parser.remaining()) {
size_t offset = parser.consumed();
// Skip type, version, and DTLS seqnums.
if (!parser.Skip(3 + EXTRA_HEADER_BYTES)) {
break;
}
nss_test::DataBuffer fragment;
if (!parser.ReadVariable(&fragment, 2)) {
break;
}
records.push_back(Record::Create(data + offset,
fragment.len() + 5 + EXTRA_HEADER_BYTES,
parser.remaining()));
}
return records;
}
namespace TlsMutators {
// Mutator that drops whole TLS records.
size_t DropRecord(uint8_t *data, size_t size, size_t maxSize,
unsigned int seed) {
std::mt19937 rng(seed);
// Find TLS records in the corpus.
auto records = ParseRecords(data, size);
if (records.empty()) {
return 0;
}
// Pick a record to drop at random.
std::uniform_int_distribution<size_t> dist(0, records.size() - 1);
auto &rec = records.at(dist(rng));
// Drop the record.
rec->drop();
// Return the new final size.
return size - rec->size();
}
// Mutator that shuffles TLS records in a transcript.
size_t ShuffleRecords(uint8_t *data, size_t size, size_t maxSize,
unsigned int seed) {
std::mt19937 rng(seed);
// Find TLS records in the corpus.
auto records = ParseRecords(data, size);
if (records.empty()) {
return 0;
}
// Store the original corpus.
std::vector<uint8_t> buf(size);
memcpy(buf.data(), data, size);
// Find offset of first record in target buffer.
uint8_t *dest =
const_cast<uint8_t *>(records.at(0)->data());
// Shuffle record order.
std::shuffle(records.begin(), records.end(), rng);
// Write records to their new positions.
for (
auto &rec : records) {
memcpy(dest, buf.data() + (rec->data() - data), rec->size());
dest += rec->size();
}
// Final size hasn't changed.
return size;
}
// Mutator that duplicates a single TLS record and randomly inserts it.
size_t DuplicateRecord(uint8_t *data, size_t size, size_t maxSize,
unsigned int seed) {
std::mt19937 rng(seed);
// Find TLS records in the corpus.
const auto records = ParseRecords(data, size);
if (records.empty()) {
return 0;
}
// Pick a record to duplicate at random.
std::uniform_int_distribution<size_t> dist(0, records.size() - 1);
auto &rec = records.at(dist(rng));
if (size + rec->size() > maxSize) {
return 0;
}
// Insert before random record.
rec->insert_before(records.at(dist(rng)));
// Return the new final size.
return size + rec->size();
}
// Mutator that truncates a TLS record.
size_t TruncateRecord(uint8_t *data, size_t size, size_t maxSize,
unsigned int seed) {
std::mt19937 rng(seed);
// Find TLS records in the corpus.
const auto records = ParseRecords(data, size);
if (records.empty()) {
return 0;
}
// Pick a record to truncate at random.
std::uniform_int_distribution<size_t> dist(0, records.size() - 1);
auto &rec = records.at(dist(rng));
// Need a record with data.
if (rec->size() <= 5 + EXTRA_HEADER_BYTES) {
return 0;
}
// Truncate.
std::uniform_int_distribution<size_t> dist2(5 + EXTRA_HEADER_BYTES,
rec->size() - 1);
size_t new_length = dist2(rng);
rec->truncate(new_length);
// Return the new final size.
return size + new_length - rec->size();
}
// Mutator that splits a TLS record in two.
size_t FragmentRecord(uint8_t *data, size_t size, size_t maxSize,
unsigned int seed) {
std::mt19937 rng(seed);
// We can't deal with DTLS yet.
if (EXTRA_HEADER_BYTES > 0) {
return 0;
}
if (size + 5 > maxSize) {
return 0;
}
// Find TLS records in the corpus.
const auto records = ParseRecords(data, size);
if (records.empty()) {
return 0;
}
// Pick a record to fragment at random.
std::uniform_int_distribution<size_t> rand_record(0, records.size() - 1);
auto &rec = records.at(rand_record(rng));
uint8_t *rdata =
const_cast<uint8_t *>(rec->data());
size_t length = rec->size();
size_t content_length = length - 5;
if (content_length < 2) {
return 0;
}
// Assign a new length to the first fragment.
std::uniform_int_distribution<size_t> rand_size(1, content_length - 1);
size_t first_length = rand_size(rng);
size_t second_length = content_length - first_length;
rdata[3] = (first_length >> 8) & 0xff;
rdata[4] = first_length & 0xff;
uint8_t *second_record = rdata + 5 + first_length;
// Make room for the header of the second record.
memmove(second_record + 5, second_record,
rec->remaining() + content_length - first_length);
// Write second header.
memcpy(second_record, rdata, 3);
second_record[3] = (second_length >> 8) & 0xff;
second_record[4] = second_length & 0xff;
return size + 5;
}
// Cross-over function that merges and shuffles two transcripts.
size_t CrossOver(
const uint8_t *data1, size_t size1,
const uint8_t *data2,
size_t size2, uint8_t *out, size_t maxOutSize,
unsigned int seed) {
std::mt19937 rng(seed);
// Find TLS records in the corpus.
auto records1 = ParseRecords(data1, size1);
if (records1.empty()) {
return 0;
}
{
// Merge the two vectors.
auto records2 = ParseRecords(data2, size2);
if (records2.empty()) {
return 0;
}
std::move(records2.begin(), records2.end(), std::back_inserter(records1));
}
// Shuffle record order.
std::shuffle(records1.begin(), records1.end(), rng);
size_t total = 0;
for (
auto &rec : records1) {
size_t length = rec->size();
if (total + length > maxOutSize) {
break;
}
// Write record to its new position.
memcpy(out + total, rec->data(), length);
total += length;
}
return total;
}
}
// namespace TlsMutators
