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// Copyright 2016 Google Inc. All rights reserved.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef SRC_MUTATOR_H_
#define SRC_MUTATOR_H_
#include <stddef.h>
#include <stdint.h>
#include <functional>
#include <memory>
#include <random>
#include <string>
#include <unordered_map>
#include <vector>
#include "port/protobuf.h"
#include "src/random.h"
namespace protobuf_mutator {
// Randomly makes incremental change in the given protobuf.
// Usage example:
// protobuf_mutator::Mutator mutator(1);
// MyMessage message;
// message.ParseFromString(encoded_message);
// mutator.Mutate(&message, 10000);
// Class implements very basic mutations of fields. E.g. it just flips bits for
// integers, floats and strings. Also it increases, decreases size of
// strings only by one. For better results users should override
// protobuf_mutator::Mutator::Mutate* methods with more useful logic, e.g. using
// library like libFuzzer.
class Mutator {
// seed: value to initialize random number generator.
Mutator() = default;
virtual ~Mutator() = default;
// Initialized internal random number generator.
void Seed(uint32_t value);
// message: message to mutate.
// max_size_hint: approximate max ByteSize() of resulting message. Method does
// not guarantee that real result will be strictly smaller than value. Caller
// could repeat mutation if result was larger than expected.
void Mutate(protobuf::Message* message, size_t max_size_hint);
void CrossOver(const protobuf::Message& message1, protobuf::Message* message2,
size_t max_size_hint);
// Makes message initialized and calls post processors to make it valid.
void Fix(protobuf::Message* message);
// Callback to postprocess mutations.
// Implementation should use seed to initialize random number generators.
using PostProcess =
std::function<void(protobuf::Message* message, unsigned int seed)>;
// Register callback which will be called after every message mutation.
// In this callback fuzzer may adjust content of the message or mutate some
// fields in some fuzzer specific way.
void RegisterPostProcessor(const protobuf::Descriptor* desc,
PostProcess callback);
// TODO(vitalybuka): Consider to replace with single mutate (uint8_t*, size).
virtual int32_t MutateInt32(int32_t value);
virtual int64_t MutateInt64(int64_t value);
virtual uint32_t MutateUInt32(uint32_t value);
virtual uint64_t MutateUInt64(uint64_t value);
virtual float MutateFloat(float value);
virtual double MutateDouble(double value);
virtual bool MutateBool(bool value);
virtual size_t MutateEnum(size_t index, size_t item_count);
virtual std::string MutateString(const std::string& value,
int size_increase_hint);
RandomEngine* random() { return &random_; }
friend class FieldMutator;
friend class TestMutator;
bool MutateImpl(const std::vector<const protobuf::Message*>& sources,
const std::vector<protobuf::Message*>& messages,
bool copy_clone_only, int size_increase_hint);
std::string MutateUtf8String(const std::string& value,
int size_increase_hint);
bool IsInitialized(const protobuf::Message& message) const;
bool keep_initialized_ = true;
size_t random_to_default_ratio_ = 100;
RandomEngine random_;
using PostProcessors =
std::unordered_multimap<const protobuf::Descriptor*, PostProcess>;
PostProcessors post_processors_;
} // namespace protobuf_mutator
#endif // SRC_MUTATOR_H_