mirror of
https://github.com/OpenVPN/openvpn3.git
synced 2024-09-20 20:13:05 +02:00
6378339776
1. Hash code is now compatible with VS 2015, so HAVE_HASH_COMBINE can be removed. 2. Added OPENVPN_HASH_METHOD macro for defining std::hash<> classes. 3. Make Hash::combine() into a varargs method.
119 lines
3.2 KiB
C++
119 lines
3.2 KiB
C++
// OpenVPN -- An application to securely tunnel IP networks
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// over a single port, with support for SSL/TLS-based
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// session authentication and key exchange,
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// packet encryption, packet authentication, and
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// packet compression.
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//
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// Copyright (C) 2012-2015 OpenVPN Technologies, Inc.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License Version 3
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// as published by the Free Software Foundation.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program in the COPYING file.
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// If not, see <http://www.gnu.org/licenses/>.
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#ifndef OPENVPN_COMMON_HASH_H
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#define OPENVPN_COMMON_HASH_H
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#include <cstring> // for std::strlen
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#include <cstdint> // for std::uint32_t, uint64_t
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#include <functional>
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#include <openvpn/common/size.hpp>
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#define OPENVPN_HASH_METHOD(T, meth) \
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namespace std { \
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template <> \
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struct hash<T> \
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{ \
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inline std::size_t operator()(const T& obj) const \
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{ \
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return obj.meth(); \
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} \
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}; \
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}
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namespace openvpn {
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namespace Hash {
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void combine_data(std::size_t& seed, const void *data, std::size_t size);
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template <class T>
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inline void combine(std::size_t& seed, const T& v)
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{
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std::hash<T> hasher;
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seed ^= hasher(v) + 0x9e3779b9 + (seed<<6) + (seed>>2);
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}
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inline void combine(std::size_t& seed, const char *str)
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{
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combine_data(seed, str, std::strlen(str));
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}
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template<typename T, typename... Args>
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inline void combine(std::size_t& seed, const T& first, Args... args)
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{
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combine(seed, first);
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combine(seed, args...);
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}
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template<typename... Args>
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inline std::size_t value(Args... args)
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{
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std::size_t hash = 0;
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combine(hash, args...);
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return hash;
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}
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// A hasher that combines a data hash with a stateful seed.
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template <typename T>
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class InitialSeed
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{
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public:
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InitialSeed(std::size_t seed) : seed_(seed) {}
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std::size_t operator()(const T& obj) const
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{
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std::size_t seed = seed_;
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combine(seed, obj);
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return seed;
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}
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private:
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std::size_t seed_;
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};
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inline void combine_data(std::size_t& seed, const void *data, std::size_t size)
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{
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while (size >= sizeof(std::uint32_t))
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{
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combine(seed, static_cast<const std::uint32_t*>(data)[0]);
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data = static_cast<const std::uint8_t*>(data) + sizeof(std::uint32_t);
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size -= sizeof(std::uint32_t);
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}
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switch (size)
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{
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case 1:
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combine(seed, static_cast<const std::uint8_t*>(data)[0]);
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break;
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case 2:
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combine(seed, static_cast<const std::uint16_t*>(data)[0]);
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break;
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case 3:
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combine(seed, static_cast<const std::uint16_t*>(data)[0]);
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combine(seed, static_cast<const std::uint8_t*>(data)[2]);
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break;
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}
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}
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}
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}
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#endif
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