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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
//
#pragma once
#include <cstdint> // for std::uint32_t, uint64_t, etc.
#include <lz4.h>
#include <openvpn/common/clamp_typerange.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/common/socktypes.hpp> // for ntohl/htonl
#include <openvpn/buffer/buffer.hpp>
using openvpn::numeric_util::clamp_to_typerange;
namespace openvpn::LZ4 {
OPENVPN_EXCEPTION(lz4_error);
inline BufferPtr compress(const ConstBuffer &src,
const size_t headroom,
const size_t tailroom)
{
// sanity check
if (src.size() > LZ4_MAX_INPUT_SIZE)
OPENVPN_THROW(lz4_error, "compress buffer size=" << src.size() << " exceeds LZ4_MAX_INPUT_SIZE=" << LZ4_MAX_INPUT_SIZE);
// allocate dest buffer
auto dest = BufferAllocatedRc::Create(sizeof(std::uint32_t) + headroom + tailroom + LZ4_COMPRESSBOUND(src.size()), 0);
dest->init_headroom(headroom);
// as a hint to receiver, write the decompressed size
{
const std::uint32_t size = htonl(clamp_to_typerange<uint32_t>(src.size()));
dest->write(&size, sizeof(size));
}
// compress
const int comp_size = ::LZ4_compress_default((const char *)src.c_data(),
(char *)dest->data_end(),
(int)src.size(),
(int)dest->remaining(tailroom));
if (comp_size <= 0)
OPENVPN_THROW(lz4_error, "LZ4_compress_default returned error status=" << comp_size);
dest->inc_size(comp_size);
return dest;
}
inline BufferPtr decompress(const ConstBuffer &source,
const size_t headroom,
const size_t tailroom,
size_t max_decompressed_size = LZ4_MAX_INPUT_SIZE)
{
// get the decompressed size
ConstBuffer src(source);
if (src.size() < sizeof(std::uint32_t))
OPENVPN_THROW(lz4_error, "decompress buffer size=" << src.size() << " is too small");
std::uint32_t size;
src.read(&size, sizeof(size));
size = ntohl(size);
if (max_decompressed_size > LZ4_MAX_INPUT_SIZE)
max_decompressed_size = LZ4_MAX_INPUT_SIZE;
if (max_decompressed_size && size > max_decompressed_size)
OPENVPN_THROW(lz4_error, "decompress expansion size=" << size << " is too large (must be <= " << max_decompressed_size << ')');
// allocate dest buffer
auto dest = BufferAllocatedRc::Create(headroom + tailroom + size, 0);
dest->init_headroom(headroom);
// decompress
const int decomp_size = LZ4_decompress_safe((const char *)src.c_data(),
(char *)dest->data(),
(int)src.size(),
size);
if (decomp_size <= 0)
OPENVPN_THROW(lz4_error, "LZ4_decompress_safe returned error status=" << decomp_size);
if (static_cast<unsigned int>(decomp_size) != size)
OPENVPN_THROW(lz4_error, "decompress size inconsistency expected_size=" << size << " actual_size=" << decomp_size);
dest->inc_size(decomp_size);
return dest;
}
} // namespace openvpn::LZ4
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