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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_COMPRESS_SNAPPY_H
#define OPENVPN_COMPRESS_SNAPPY_H
// Implement Snappy compression.
// Should only be included by compress.hpp
#include <snappy.h>
namespace openvpn {
class CompressSnappy : public Compress
{
// magic number for Snappy compression
enum
{
SNAPPY_COMPRESS = 0x68,
};
public:
CompressSnappy(const Frame::Ptr &frame, const SessionStats::Ptr &stats, const bool asym_arg)
: Compress(frame, stats),
asym(asym_arg)
{
OVPN_LOG_INFO("SNAPPY init asym=" << asym_arg);
}
const char *name() const override
{
return "snappy";
}
void compress(BufferAllocated &buf, const bool hint) override
{
// skip null packets
if (!buf.size())
return;
if (hint && !asym)
{
// initialize work buffer
frame->prepare(Frame::COMPRESS_WORK, work);
// verify that input data length is not too large
if (snappy::MaxCompressedLength(buf.size()) > work.max_size())
{
error(buf);
return;
}
// do compress
size_t comp_size;
snappy::RawCompress((const char *)buf.c_data(), buf.size(), (char *)work.data(), &comp_size);
// did compression actually reduce data length?
if (comp_size < buf.size())
{
OVPN_LOG_VERBOSE("SNAPPY compress " << buf.size() << " -> " << comp_size);
work.set_size(comp_size);
do_swap(work, SNAPPY_COMPRESS);
buf.swap(work);
return;
}
}
// indicate that we didn't compress
do_swap(buf, NO_COMPRESS_SWAP);
}
void decompress(BufferAllocated &buf) override
{
// skip null packets
if (!buf.size())
return;
const unsigned char c = buf.pop_front();
switch (c)
{
case NO_COMPRESS_SWAP:
do_unswap(buf);
break;
case SNAPPY_COMPRESS:
{
do_unswap(buf);
// initialize work buffer
const size_t payload_size = frame->prepare(Frame::DECOMPRESS_WORK, work);
// do uncompress
size_t decomp_size;
if (!snappy::GetUncompressedLength((const char *)buf.c_data(), buf.size(), &decomp_size)
|| decomp_size > payload_size)
{
error(buf);
break;
}
if (!snappy::RawUncompress((const char *)buf.c_data(), buf.size(), (char *)work.data()))
{
error(buf);
break;
}
OVPN_LOG_VERBOSE("SNAPPY uncompress " << buf.size() << " -> " << decomp_size);
work.set_size(decomp_size);
buf.swap(work);
}
break;
default:
error(buf); // unknown op
break;
}
}
private:
const bool asym;
BufferAllocated work;
};
} // namespace openvpn
#endif // OPENVPN_COMPRESS_SNAPPY_H
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