diff options
Diffstat (limited to 'src/plugins/utilities/uuid')
| -rw-r--r-- | src/plugins/utilities/uuid/UUIDGeneration.cpp | 137 | ||||
| -rw-r--r-- | src/plugins/utilities/uuid/UUIDGeneration.h | 42 |
2 files changed, 179 insertions, 0 deletions
diff --git a/src/plugins/utilities/uuid/UUIDGeneration.cpp b/src/plugins/utilities/uuid/UUIDGeneration.cpp new file mode 100644 index 0000000..bb03fc6 --- /dev/null +++ b/src/plugins/utilities/uuid/UUIDGeneration.cpp @@ -0,0 +1,137 @@ +/* + * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. 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. + * A copy of the License is located at + * + * http://aws.amazon.com/apache2.0/ + * + * or in the "license" file accompanying this file. This file is distributed + * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either + * express or implied. See the License for the specific language governing + * permissions and limitations under the License. + */ +// This code is copied from https://github.com/alexa/avs-device-sdk/ +// Minor modifications are made to the original file. + +#include <random> +#include <chrono> +#include <sstream> +#include <iomanip> +#include <mutex> +#include <climits> +#include <algorithm> +#include <functional> + +#include "utilities/uuid/UUIDGeneration.h" + +namespace vshl { +namespace utilities { +namespace uuid { + +/// String to identify log entries originating from this file. +static const std::string TAG("UUIDGeneration"); + +/// The UUID version (Version 4), shifted into the correct position in the byte. +static const uint8_t UUID_VERSION_VALUE = 4 << 4; + +/// The UUID variant (Variant 1), shifted into the correct position in the byte. +static const size_t UUID_VARIANT_VALUE = 2 << 6; + +/// Separator used between UUID fields. +static const std::string SEPARATOR("-"); + +/// Number of bits in the replacement value. +static const size_t MAX_NUM_REPLACEMENT_BITS = CHAR_BIT; + +/// Number of bits in a hex digit. +static const size_t BITS_IN_HEX_DIGIT = 4; + +/** + * Randomly generate a string of hex digits. Before the conversion of hex to string, + * the function allows replacement of the bits of the first two generated hex digits. + * Replacement happens starting at the most significant, to the least significant bit. + * + * @param ibe A random number generator. + * @param numDigits The number of hex digits [0-9],[a-f] to generate. + * @param replacementBits The replacement value for up to the first two digits generated. + * @param numReplacementBits The number of bits of @c replacementBits to use. + * + * @return A hex string of length @c numDigits. + */ +static const std::string generateHexWithReplacement( + std::independent_bits_engine<std::default_random_engine, CHAR_BIT, uint8_t>& ibe, + unsigned int numDigits, + uint8_t replacementBits, + unsigned short numReplacementBits) { + if (numReplacementBits > MAX_NUM_REPLACEMENT_BITS) { + return ""; + } + + if (numReplacementBits > (numDigits * BITS_IN_HEX_DIGIT)) { + return ""; + } + + // Makes assumption that 1 digit = 4 bits. + std::vector<uint8_t> bytes(ceil(numDigits / 2.0)); + std::generate(bytes.begin(), bytes.end(), std::ref(ibe)); + + // Replace the specified number of bits from the first byte. + bytes.at(0) &= (0xff >> numReplacementBits); + replacementBits &= (0xff << (MAX_NUM_REPLACEMENT_BITS - numReplacementBits)); + bytes.at(0) |= replacementBits; + + std::ostringstream oss; + for (const auto& byte : bytes) { + oss << std::hex << std::setfill('0') << std::setw(2) << static_cast<int>(byte); + } + + std::string bytesText = oss.str(); + // Remove the last digit for odd numDigits case. + bytesText.resize(numDigits); + + return bytesText; +} + +/** + * Randomly generate a string of hex digits. + * + * @param ibe A random number generator. + * @param numDigits The number of hex digits [0-9],[a-f] to generate. + * + * @return A hex string of length @c numDigits. + */ +static const std::string generateHex( + std::independent_bits_engine<std::default_random_engine, CHAR_BIT, uint8_t>& ibe, + unsigned int numDigits) { + return generateHexWithReplacement(ibe, numDigits, 0, 0); +} + +const std::string generateUUID() { + static bool seeded = false; + static std::independent_bits_engine<std::default_random_engine, CHAR_BIT, uint8_t> ibe; + static std::mutex mutex; + std::unique_lock<std::mutex> lock(mutex); + if (!seeded) { + std::random_device rd; + ibe.seed( + rd() + + std::chrono::duration_cast<std::chrono::nanoseconds>(std::chrono::steady_clock::now().time_since_epoch()) + .count()); + seeded = true; + } + + std::ostringstream uuidText; + uuidText << generateHex(ibe, 8) << SEPARATOR << generateHex(ibe, 4) << SEPARATOR + << generateHexWithReplacement(ibe, 4, UUID_VERSION_VALUE, 4) << SEPARATOR + << generateHexWithReplacement(ibe, 4, UUID_VARIANT_VALUE, 2) << SEPARATOR << generateHex(ibe, 12); + + lock.unlock(); + + return uuidText.str(); +} + +} // namespace uuid +} // namespace utilities +} // namespace vshl diff --git a/src/plugins/utilities/uuid/UUIDGeneration.h b/src/plugins/utilities/uuid/UUIDGeneration.h new file mode 100644 index 0000000..7af9cb1 --- /dev/null +++ b/src/plugins/utilities/uuid/UUIDGeneration.h @@ -0,0 +1,42 @@ +/* + * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. 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. + * A copy of the License is located at + * + * http://aws.amazon.com/apache2.0/ + * + * or in the "license" file accompanying this file. This file is distributed + * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either + * express or implied. See the License for the specific language governing + * permissions and limitations under the License. + */ +// This code is copied from https://github.com/alexa/avs-device-sdk/ +// Minor modifications are made to the original file. + +#ifndef VSHL_UTILITIES_UUID_UUIDGENERATION_H_ +#define VSHL_UTILITIES_UUID_UUIDGENERATION_H_ + +#include <string> + +namespace vshl { +namespace utilities { +namespace uuid { + +/** + * Generates a variant 1, version 4 universally unique identifier (UUID) consisting of 32 hexadecimal digits. + * The UUID generated is of the format xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx where M indicates the version, and the two + * most significant bits of N indicates the variant. M is 0100 (binary) for version 4 and N is 10xx(binary) for + * variant 1. + * @see https://tools.ietf.org/html/rfc4122. + * + * @return A uuid as a string. + */ +const std::string generateUUID(); + +} // namespace uuid +} // namespace utilities +} // namespace vshl + +#endif // VSHL_UTILITIES_UUID_UUIDGENERATION_H_
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