1 files changed, 220 insertions, 0 deletions
diff --git a/third_party/libwebrtc/rtc_base/helpers.cc b/third_party/libwebrtc/rtc_base/helpers.cc
new file mode 100644
index 0000000000..337239894a
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/helpers.cc
@@ -0,0 +1,220 @@
+/*
+ *  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