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TMessagesProj/jni/voip/webrtc/rtc_base/helpers.h

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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.
+ */
+
+#ifndef RTC_BASE_HELPERS_H_
+#define RTC_BASE_HELPERS_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <memory>
+#include <string>
+
+#include "absl/strings/string_view.h"
+#include "rtc_base/system/rtc_export.h"
+
+namespace rtc {
+
+// Interface 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;
+};
+
+// Sets the default random generator as the source of randomness. The default
+// source uses the OpenSSL RNG and provides cryptographically secure randomness.
+void SetDefaultRandomGenerator();
+
+// Set a custom random generator. Results produced by CreateRandomXyz
+// are cryptographically random iff the output of the supplied generator is
+// cryptographically random.
+void SetRandomGenerator(std::unique_ptr<RandomGenerator> generator);
+
+// For testing, we can return predictable data.
+void SetRandomTestMode(bool test);
+
+// Initializes the RNG, and seeds it with the specified entropy.
+bool InitRandom(int seed);
+bool InitRandom(const char* seed, size_t len);
+
+// Generates a (cryptographically) random string of the given length.
+// We generate base64 values so that they will be printable.
+RTC_EXPORT std::string CreateRandomString(size_t length);
+
+// Generates a (cryptographically) random string of the given length.
+// We generate base64 values so that they will be printable.
+// Return false if the random number generator failed.
+RTC_EXPORT bool CreateRandomString(size_t length, std::string* str);
+
+// Generates a (cryptographically) random string of the given length,
+// with characters from the given table. Return false if the random
+// number generator failed.
+// For ease of implementation, the function requires that the table
+// size evenly divide 256; otherwise, it returns false.
+RTC_EXPORT bool CreateRandomString(size_t length,
+                                   absl::string_view table,
+                                   std::string* str);
+
+// Generates (cryptographically) random data of the given length.
+// Return false if the random number generator failed.
+bool CreateRandomData(size_t length, std::string* data);
+
+// Generates a (cryptographically) random UUID version 4 string.
+std::string CreateRandomUuid();
+
+// Generates a random id.
+uint32_t CreateRandomId();
+
+// Generates a 64 bit random id.
+RTC_EXPORT uint64_t CreateRandomId64();
+
+// Generates a random id > 0.
+uint32_t CreateRandomNonZeroId();
+
+// Generates a random double between 0.0 (inclusive) and 1.0 (exclusive).
+double CreateRandomDouble();
+
+// Compute moving average with the given ratio between the previous average
+// value and the current value.
+double GetNextMovingAverage(double prev_average, double cur, double ratio);
+
+}  // namespace rtc
+
+#endif  // RTC_BASE_HELPERS_H_