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/*
* Copyright 2004 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "rtc_base/helpers.h"
#include <openssl/rand.h>
#include <cstdint>
#include <limits>
#include <memory>
#include "absl/strings/string_view.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
// Protect against max macro inclusion.
#undef max
namespace rtc {
// Base class for RNG implementations.
class RandomGenerator {
public:
virtual ~RandomGenerator() {}
virtual bool Init(const void* seed, size_t len) = 0;
virtual bool Generate(void* buf, size_t len) = 0;
};
// The OpenSSL RNG.
class SecureRandomGenerator : public RandomGenerator {
public:
SecureRandomGenerator() {}
~SecureRandomGenerator() override {}
bool Init(const void* seed, size_t len) override { return true; }
bool Generate(void* buf, size_t len) override {
return (RAND_bytes(reinterpret_cast<unsigned char*>(buf), len) > 0);
}
};
// A test random generator, for predictable output.
class TestRandomGenerator : public RandomGenerator {
public:
TestRandomGenerator() : seed_(7) {}
~TestRandomGenerator() override {}
bool Init(const void* seed, size_t len) override { return true; }
bool Generate(void* buf, size_t len) override {
for (size_t i = 0; i < len; ++i) {
static_cast<uint8_t*>(buf)[i] = static_cast<uint8_t>(GetRandom());
}
return true;
}
private:
int GetRandom() {
return ((seed_ = seed_ * 214013L + 2531011L) >> 16) & 0x7fff;
}
int seed_;
};
namespace {
// TODO: Use Base64::Base64Table instead.
static const char kBase64[64] = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'};
static const char kHex[16] = {'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
static const char kUuidDigit17[4] = {'8', '9', 'a', 'b'};
// This round about way of creating a global RNG is to safe-guard against
// indeterminant static initialization order.
std::unique_ptr<RandomGenerator>& GetGlobalRng() {
static std::unique_ptr<RandomGenerator>& global_rng =
*new std::unique_ptr<RandomGenerator>(new SecureRandomGenerator());
return global_rng;
}
RandomGenerator& Rng() {
return *GetGlobalRng();
}
} // namespace
void SetRandomTestMode(bool test) {
if (!test) {
GetGlobalRng().reset(new SecureRandomGenerator());
} else {
GetGlobalRng().reset(new TestRandomGenerator());
}
}
bool InitRandom(int seed) {
return InitRandom(reinterpret_cast<const char*>(&seed), sizeof(seed));
}
bool InitRandom(const char* seed, size_t len) {
if (!Rng().Init(seed, len)) {
RTC_LOG(LS_ERROR) << "Failed to init random generator!";
return false;
}
return true;
}
std::string CreateRandomString(size_t len) {
std::string str;
RTC_CHECK(CreateRandomString(len, &str));
return str;
}
static bool CreateRandomString(size_t len,
const char* table,
int table_size,
std::string* str) {
str->clear();
// Avoid biased modulo division below.
if (256 % table_size) {
RTC_LOG(LS_ERROR) << "Table size must divide 256 evenly!";
return false;
}
std::unique_ptr<uint8_t[]> bytes(new uint8_t[len]);
if (!Rng().Generate(bytes.get(), len)) {
RTC_LOG(LS_ERROR) << "Failed to generate random string!";
return false;
}
str->reserve(len);
for (size_t i = 0; i < len; ++i) {
str->push_back(table[bytes[i] % table_size]);
}
return true;
}
bool CreateRandomString(size_t len, std::string* str) {
return CreateRandomString(len, kBase64, 64, str);
}
bool CreateRandomString(size_t len, absl::string_view table, std::string* str) {
return CreateRandomString(len, table.data(), static_cast<int>(table.size()),
str);
}
bool CreateRandomData(size_t length, std::string* data) {
data->resize(length);
// std::string is guaranteed to use contiguous memory in c++11 so we can
// safely write directly to it.
return Rng().Generate(&data->at(0), length);
}
// Version 4 UUID is of the form:
// xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
// Where 'x' is a hex digit, and 'y' is 8, 9, a or b.
std::string CreateRandomUuid() {
std::string str;
std::unique_ptr<uint8_t[]> bytes(new uint8_t[31]);
RTC_CHECK(Rng().Generate(bytes.get(), 31));
str.reserve(36);
for (size_t i = 0; i < 8; ++i) {
str.push_back(kHex[bytes[i] % 16]);
}
str.push_back('-');
for (size_t i = 8; i < 12; ++i) {
str.push_back(kHex[bytes[i] % 16]);
}
str.push_back('-');
str.push_back('4');
for (size_t i = 12; i < 15; ++i) {
str.push_back(kHex[bytes[i] % 16]);
}
str.push_back('-');
str.push_back(kUuidDigit17[bytes[15] % 4]);
for (size_t i = 16; i < 19; ++i) {
str.push_back(kHex[bytes[i] % 16]);
}
str.push_back('-');
for (size_t i = 19; i < 31; ++i) {
str.push_back(kHex[bytes[i] % 16]);
}
return str;
}
uint32_t CreateRandomId() {
uint32_t id;
RTC_CHECK(Rng().Generate(&id, sizeof(id)));
return id;
}
uint64_t CreateRandomId64() {
return static_cast<uint64_t>(CreateRandomId()) << 32 | CreateRandomId();
}
uint32_t CreateRandomNonZeroId() {
uint32_t id;
do {
id = CreateRandomId();
} while (id == 0);
return id;
}
double CreateRandomDouble() {
return CreateRandomId() / (std::numeric_limits<uint32_t>::max() +
std::numeric_limits<double>::epsilon());
}
double GetNextMovingAverage(double prev_average, double cur, double ratio) {
return (ratio * prev_average + cur) / (ratio + 1);
}
} // namespace rtc
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