mirror of
https://github.com/OpenVPN/openvpn3.git
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68 lines
2.2 KiB
C++
68 lines
2.2 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_BINPREFIX_H
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#define OPENVPN_COMMON_BINPREFIX_H
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#include <algorithm> // for std::min, std::max
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#include <cstring> // for std::memset, std::memcpy
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#include <cstdint> // for std::uint32_t, uint64_t
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#include <openvpn/common/socktypes.hpp> // for ntohl
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namespace openvpn {
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// Return the binary prefix of a big-endian data buffer
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// as a 32 or 64 bit type.
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template <typename T>
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inline T bin_prefix(const unsigned char *data)
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{
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static_assert(sizeof(T) == 4 || sizeof(T) == 8, "size inconsistency");
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if (sizeof(T) == 8)
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return (T(ntohl(*(uint32_t *)&data[0])) << 32) | T(ntohl(*(uint32_t *)&data[4]));
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else // sizeof(T) == 4
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return T(ntohl(*(uint32_t *)&data[0]));
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}
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template <typename T>
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inline T bin_prefix(const unsigned char *data, const size_t len)
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{
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unsigned char d[sizeof(T)]
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#ifndef _MSC_VER
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__attribute__((aligned(sizeof(T))))
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#endif
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;
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const size_t l = std::min(len, sizeof(d));
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std::memset(d, 0, sizeof(d));
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std::memcpy(d + sizeof(d) - l, data, l);
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return bin_prefix<T>(d);
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}
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template <typename T>
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inline T bin_prefix_floor(const unsigned char *data, const size_t len, const T floor)
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{
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return std::max(bin_prefix<T>(data, len), floor);
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}
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}
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#endif
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