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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
//
// This is a "stub" compression object. It acts like a compressor
// in the sense that it plays along with compression framing in
// the OpenVPN protocol, but it always sends packets with NO_COMPRESS
// or NO_COMPRESS_SWAP compression status. While it's not designed
// to receive compressed packets, it will try to handle received LZO
// packets, but it will never send compressed packets.
#ifndef OPENVPN_COMPRESS_COMPSTUB_H
#define OPENVPN_COMPRESS_COMPSTUB_H
#ifndef NO_LZO
#include <openvpn/compress/lzoselect.hpp>
#endif
namespace openvpn {
class CompressStub : public Compress
{
public:
CompressStub(const Frame::Ptr &frame, const SessionStats::Ptr &stats, const bool support_swap_arg)
: Compress(frame, stats),
support_swap(support_swap_arg)
#ifndef NO_LZO
,
lzo(frame, stats, false, true)
#endif
{
OVPN_LOG_INFO("Comp-stub init swap=" << support_swap_arg);
}
const char *name() const override
{
return "stub";
}
void compress(BufferAllocated &buf, const bool hint) override
{
// skip null packets
if (!buf.size())
return;
// indicate that we didn't compress
if (support_swap)
do_swap(buf, NO_COMPRESS_SWAP);
else
buf.push_front(NO_COMPRESS);
}
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);
case NO_COMPRESS:
break;
#ifndef NO_LZO
// special mode to support older servers that ignore
// compression handshake -- this will handle receiving
// compressed packets even if we didn't ask for them
case CompressLZO::LZO_COMPRESS:
OVPN_LOG_VERBOSE("CompressStub: handled unsolicited LZO packet");
lzo.decompress_work(buf);
break;
#endif
default:
OVPN_LOG_VERBOSE("CompressStub: unable to handle op=" << int(c));
error(buf);
}
}
private:
const bool support_swap;
#ifndef NO_LZO
CompressLZO lzo;
#endif
};
// Compression stub using V2 protocol
class CompressStubV2 : public Compress
{
public:
CompressStubV2(const Frame::Ptr &frame, const SessionStats::Ptr &stats)
: Compress(frame, stats)
{
OVPN_LOG_INFO("Comp-stubV2 init");
}
const char *name() const override
{
return "stubv2";
}
void compress(BufferAllocated &buf, const bool hint) override
{
// skip null packets
if (!buf.size())
return;
// indicate that we didn't compress
v2_push(buf, OVPN_COMPv2_NONE);
}
void decompress(BufferAllocated &buf) override
{
// skip null packets
if (!buf.size())
return;
const int cop = v2_pull(buf);
if (cop)
{
OVPN_LOG_VERBOSE("CompressStubV2: unable to handle op=" << cop);
error(buf);
}
}
};
} // namespace openvpn
#endif // OPENVPN_COMPRESS_COMPSTUB_H
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