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| 1 /* | |
| 2 * Copyright 2004 The WebRTC Project Authors. All rights reserved. | |
| 3 * | |
| 4 * Use of this source code is governed by a BSD-style license | |
| 5 * that can be found in the LICENSE file in the root of the source | |
| 6 * tree. An additional intellectual property rights grant can be found | |
| 7 * in the file PATENTS. All contributing project authors may | |
| 8 * be found in the AUTHORS file in the root of the source tree. | |
| 9 */ | |
| 10 | |
| 11 #include "webrtc/base/helpers.h" | |
| 12 | |
| 13 #include <limits> | |
| 14 #include <memory> | |
| 15 | |
| 16 #include <openssl/rand.h> | |
| 17 | |
| 18 #include "webrtc/base/base64.h" | |
| 19 #include "webrtc/base/basictypes.h" | |
| 20 #include "webrtc/base/checks.h" | |
| 21 #include "webrtc/base/logging.h" | |
| 22 #include "webrtc/base/timeutils.h" | |
| 23 | |
| 24 // Protect against max macro inclusion. | |
| 25 #undef max | |
| 26 | |
| 27 namespace rtc { | |
| 28 | |
| 29 // Base class for RNG implementations. | |
| 30 class RandomGenerator { | |
| 31 public: | |
| 32 virtual ~RandomGenerator() {} | |
| 33 virtual bool Init(const void* seed, size_t len) = 0; | |
| 34 virtual bool Generate(void* buf, size_t len) = 0; | |
| 35 }; | |
| 36 | |
| 37 // The OpenSSL RNG. | |
| 38 class SecureRandomGenerator : public RandomGenerator { | |
| 39 public: | |
| 40 SecureRandomGenerator() {} | |
| 41 ~SecureRandomGenerator() override {} | |
| 42 bool Init(const void* seed, size_t len) override { return true; } | |
| 43 bool Generate(void* buf, size_t len) override { | |
| 44 return (RAND_bytes(reinterpret_cast<unsigned char*>(buf), len) > 0); | |
| 45 } | |
| 46 }; | |
| 47 | |
| 48 // A test random generator, for predictable output. | |
| 49 class TestRandomGenerator : public RandomGenerator { | |
| 50 public: | |
| 51 TestRandomGenerator() : seed_(7) { | |
| 52 } | |
| 53 ~TestRandomGenerator() override { | |
| 54 } | |
| 55 bool Init(const void* seed, size_t len) override { return true; } | |
| 56 bool Generate(void* buf, size_t len) override { | |
| 57 for (size_t i = 0; i < len; ++i) { | |
| 58 static_cast<uint8_t*>(buf)[i] = static_cast<uint8_t>(GetRandom()); | |
| 59 } | |
| 60 return true; | |
| 61 } | |
| 62 | |
| 63 private: | |
| 64 int GetRandom() { | |
| 65 return ((seed_ = seed_ * 214013L + 2531011L) >> 16) & 0x7fff; | |
| 66 } | |
| 67 int seed_; | |
| 68 }; | |
| 69 | |
| 70 namespace { | |
| 71 | |
| 72 // TODO: Use Base64::Base64Table instead. | |
| 73 static const char kBase64[64] = { | |
| 74 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', | |
| 75 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', | |
| 76 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', | |
| 77 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', | |
| 78 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'}; | |
| 79 | |
| 80 static const char kHex[16] = {'0', '1', '2', '3', '4', '5', '6', '7', | |
| 81 '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}; | |
| 82 | |
| 83 static const char kUuidDigit17[4] = {'8', '9', 'a', 'b'}; | |
| 84 | |
| 85 // This round about way of creating a global RNG is to safe-guard against | |
| 86 // indeterminant static initialization order. | |
| 87 std::unique_ptr<RandomGenerator>& GetGlobalRng() { | |
| 88 RTC_DEFINE_STATIC_LOCAL(std::unique_ptr<RandomGenerator>, global_rng, | |
| 89 (new SecureRandomGenerator())); | |
| 90 return global_rng; | |
| 91 } | |
| 92 | |
| 93 RandomGenerator& Rng() { | |
| 94 return *GetGlobalRng(); | |
| 95 } | |
| 96 | |
| 97 } // namespace | |
| 98 | |
| 99 void SetRandomTestMode(bool test) { | |
| 100 if (!test) { | |
| 101 GetGlobalRng().reset(new SecureRandomGenerator()); | |
| 102 } else { | |
| 103 GetGlobalRng().reset(new TestRandomGenerator()); | |
| 104 } | |
| 105 } | |
| 106 | |
| 107 bool InitRandom(int seed) { | |
| 108 return InitRandom(reinterpret_cast<const char*>(&seed), sizeof(seed)); | |
| 109 } | |
| 110 | |
| 111 bool InitRandom(const char* seed, size_t len) { | |
| 112 if (!Rng().Init(seed, len)) { | |
| 113 LOG(LS_ERROR) << "Failed to init random generator!"; | |
| 114 return false; | |
| 115 } | |
| 116 return true; | |
| 117 } | |
| 118 | |
| 119 std::string CreateRandomString(size_t len) { | |
| 120 std::string str; | |
| 121 RTC_CHECK(CreateRandomString(len, &str)); | |
| 122 return str; | |
| 123 } | |
| 124 | |
| 125 static bool CreateRandomString(size_t len, | |
| 126 const char* table, int table_size, | |
| 127 std::string* str) { | |
| 128 str->clear(); | |
| 129 // Avoid biased modulo division below. | |
| 130 if (256 % table_size) { | |
| 131 LOG(LS_ERROR) << "Table size must divide 256 evenly!"; | |
| 132 return false; | |
| 133 } | |
| 134 std::unique_ptr<uint8_t[]> bytes(new uint8_t[len]); | |
| 135 if (!Rng().Generate(bytes.get(), len)) { | |
| 136 LOG(LS_ERROR) << "Failed to generate random string!"; | |
| 137 return false; | |
| 138 } | |
| 139 str->reserve(len); | |
| 140 for (size_t i = 0; i < len; ++i) { | |
| 141 str->push_back(table[bytes[i] % table_size]); | |
| 142 } | |
| 143 return true; | |
| 144 } | |
| 145 | |
| 146 bool CreateRandomString(size_t len, std::string* str) { | |
| 147 return CreateRandomString(len, kBase64, 64, str); | |
| 148 } | |
| 149 | |
| 150 bool CreateRandomString(size_t len, const std::string& table, | |
| 151 std::string* str) { | |
| 152 return CreateRandomString(len, table.c_str(), | |
| 153 static_cast<int>(table.size()), str); | |
| 154 } | |
| 155 | |
| 156 bool CreateRandomData(size_t length, std::string* data) { | |
| 157 data->resize(length); | |
| 158 // std::string is guaranteed to use contiguous memory in c++11 so we can | |
| 159 // safely write directly to it. | |
| 160 return Rng().Generate(&data->at(0), length); | |
| 161 } | |
| 162 | |
| 163 // Version 4 UUID is of the form: | |
| 164 // xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx | |
| 165 // Where 'x' is a hex digit, and 'y' is 8, 9, a or b. | |
| 166 std::string CreateRandomUuid() { | |
| 167 std::string str; | |
| 168 std::unique_ptr<uint8_t[]> bytes(new uint8_t[31]); | |
| 169 RTC_CHECK(Rng().Generate(bytes.get(), 31)); | |
| 170 str.reserve(36); | |
| 171 for (size_t i = 0; i < 8; ++i) { | |
| 172 str.push_back(kHex[bytes[i] % 16]); | |
| 173 } | |
| 174 str.push_back('-'); | |
| 175 for (size_t i = 8; i < 12; ++i) { | |
| 176 str.push_back(kHex[bytes[i] % 16]); | |
| 177 } | |
| 178 str.push_back('-'); | |
| 179 str.push_back('4'); | |
| 180 for (size_t i = 12; i < 15; ++i) { | |
| 181 str.push_back(kHex[bytes[i] % 16]); | |
| 182 } | |
| 183 str.push_back('-'); | |
| 184 str.push_back(kUuidDigit17[bytes[15] % 4]); | |
| 185 for (size_t i = 16; i < 19; ++i) { | |
| 186 str.push_back(kHex[bytes[i] % 16]); | |
| 187 } | |
| 188 str.push_back('-'); | |
| 189 for (size_t i = 19; i < 31; ++i) { | |
| 190 str.push_back(kHex[bytes[i] % 16]); | |
| 191 } | |
| 192 return str; | |
| 193 } | |
| 194 | |
| 195 uint32_t CreateRandomId() { | |
| 196 uint32_t id; | |
| 197 RTC_CHECK(Rng().Generate(&id, sizeof(id))); | |
| 198 return id; | |
| 199 } | |
| 200 | |
| 201 uint64_t CreateRandomId64() { | |
| 202 return static_cast<uint64_t>(CreateRandomId()) << 32 | CreateRandomId(); | |
| 203 } | |
| 204 | |
| 205 uint32_t CreateRandomNonZeroId() { | |
| 206 uint32_t id; | |
| 207 do { | |
| 208 id = CreateRandomId(); | |
| 209 } while (id == 0); | |
| 210 return id; | |
| 211 } | |
| 212 | |
| 213 double CreateRandomDouble() { | |
| 214 return CreateRandomId() / (std::numeric_limits<uint32_t>::max() + | |
| 215 std::numeric_limits<double>::epsilon()); | |
| 216 } | |
| 217 | |
| 218 } // namespace rtc | |
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