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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012- OpenVPN Inc.
//
// SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
#ifndef OPENVPN_COMMON_BINPREFIX_H
#define OPENVPN_COMMON_BINPREFIX_H
#include <algorithm> // for std::min, std::max
#include <cstring> // for std::memset, std::memcpy
#include <cstdint> // for std::uint32_t, uint64_t
#include <openvpn/common/socktypes.hpp> // for ntohl
namespace openvpn {
// Return the binary prefix of a big-endian data buffer
// as a 32 bit type.
template <typename T>
inline typename std::enable_if<4 == sizeof(T), T>::type
bin_prefix(const unsigned char *data)
{
static_assert(sizeof(T) == 4, "size inconsistency");
return T(ntohl(*(uint32_t *)&data[0]));
}
// Return the binary prefix of a big-endian data buffer
// as a 64 bit type.
template <typename T>
inline typename std::enable_if<8 == sizeof(T), T>::type
bin_prefix(const unsigned char *data)
{
static_assert(sizeof(T) == 8, "size inconsistency");
return (T(ntohl(*(uint32_t *)&data[0])) << 32) | T(ntohl(*(uint32_t *)&data[4]));
}
template <typename T>
inline T bin_prefix(const unsigned char *data, const size_t len)
{
unsigned char d[sizeof(T)]
#ifndef _MSC_VER
__attribute__((aligned(sizeof(T))))
#endif
;
const size_t l = std::min(len, sizeof(d));
std::memset(d, 0, sizeof(d));
std::memcpy(d + sizeof(d) - l, data, l);
return bin_prefix<T>(d);
}
template <typename T>
inline T bin_prefix_floor(const unsigned char *data, const size_t len, const T floor)
{
return std::max(bin_prefix<T>(data, len), floor);
}
} // namespace openvpn
#endif
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