mirror of
https://github.com/OpenVPN/openvpn3.git
synced 2024-09-20 20:13:05 +02:00
76 lines
2.3 KiB
C++
76 lines
2.3 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 <boost/cstdint.hpp> // for boost::uint32_t, uint64_t
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#include <boost/functional/hash.hpp>
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#include <openvpn/common/types.hpp>
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namespace openvpn {
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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 HashInitialSeed
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{
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public:
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HashInitialSeed(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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boost::hash_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 hash_combine_data(std::size_t& seed, const void *data, std::size_t size)
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{
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while (size >= sizeof(boost::uint32_t))
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{
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boost::hash_combine(seed, static_cast<const boost::uint32_t*>(data)[0]);
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data = static_cast<const boost::uint8_t*>(data) + sizeof(boost::uint32_t);
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size -= sizeof(boost::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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boost::hash_combine(seed, static_cast<const boost::uint8_t*>(data)[0]);
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break;
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case 2:
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boost::hash_combine(seed, static_cast<const boost::uint16_t*>(data)[0]);
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break;
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case 3:
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boost::hash_combine(seed, static_cast<const boost::uint16_t*>(data)[0]);
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boost::hash_combine(seed, static_cast<const boost::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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#endif
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