mirror of
https://github.com/OpenVPN/openvpn3.git
synced 2024-09-20 04:02:15 +02:00
8c94a8f774
Signed-off-by: David Sommerseth <davids@openvpn.net>
228 lines
5.3 KiB
C++
228 lines
5.3 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) 2012-2022 OpenVPN 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_COMPRESS_LZ4_H
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#define OPENVPN_COMPRESS_LZ4_H
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// Implement LZ4 compression.
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// Should only be included by compress.hpp
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#include <algorithm> // for std::max
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#include <lz4.h>
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namespace openvpn {
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class CompressLZ4Base : public Compress
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{
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protected:
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CompressLZ4Base(const Frame::Ptr& frame, const SessionStats::Ptr& stats)
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: Compress(frame, stats)
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{
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}
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bool do_decompress(BufferAllocated& buf)
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{
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// initialize work buffer
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const int payload_size = frame->prepare(Frame::DECOMPRESS_WORK, work);
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// do uncompress
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const int decomp_size = LZ4_decompress_safe((const char *)buf.c_data(), (char *)work.data(),
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(int)buf.size(), payload_size);
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if (decomp_size < 0)
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{
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error(buf);
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return false;
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}
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OPENVPN_LOG_COMPRESS_VERBOSE("LZ4 uncompress " << buf.size() << " -> " << decomp_size);
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work.set_size(decomp_size);
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buf.swap(work);
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return true;
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}
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bool do_compress(BufferAllocated& buf)
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{
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// initialize work buffer
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frame->prepare(Frame::COMPRESS_WORK, work);
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// verify that input data length is not too large
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if (lz4_extra_buffer(buf.size()) > work.max_size())
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{
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error(buf);
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return false;
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}
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// do compress
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const unsigned int comp_size = LZ4_compress_default((const char *)buf.c_data(), (char *)work.data(),
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(int)buf.size(), (int)work.capacity());
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// did compression actually reduce data length?
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if (comp_size < buf.size())
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{
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if (comp_size <= 0)
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{
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error(buf);
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return false;
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}
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OPENVPN_LOG_COMPRESS_VERBOSE("LZ4 compress " << buf.size() << " -> " << comp_size);
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work.set_size(comp_size);
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buf.swap(work);
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return true;
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}
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else
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return false;
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}
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// Worst case size expansion on compress.
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// Official LZ4 worst-case size expansion alg is
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// LZ4_COMPRESSBOUND macro in lz4.h.
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// However we optimize it slightly here to lose the integer division
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// when len < 65535.
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size_t lz4_extra_buffer(const size_t len)
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{
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if (likely(len < 65535))
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return len + len/256 + 17;
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else
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return len + len/255 + 16;
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}
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BufferAllocated work;
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};
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class CompressLZ4 : public CompressLZ4Base
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{
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// magic number for LZ4 compression
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enum {
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LZ4_COMPRESS = 0x69,
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};
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public:
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CompressLZ4(const Frame::Ptr& frame, const SessionStats::Ptr& stats, const bool asym_arg)
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: CompressLZ4Base(frame, stats),
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asym(asym_arg)
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{
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OPENVPN_LOG_COMPRESS("LZ4 init asym=" << asym_arg);
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}
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virtual const char *name() const { return "lz4"; }
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virtual void compress(BufferAllocated& buf, const bool hint)
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{
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// skip null packets
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if (!buf.size())
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return;
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if (hint && !asym)
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{
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if (do_compress(buf))
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{
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do_swap(buf, LZ4_COMPRESS);
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return;
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}
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}
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// indicate that we didn't compress
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do_swap(buf, NO_COMPRESS_SWAP);
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}
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virtual void decompress(BufferAllocated& buf)
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{
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// skip null packets
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if (!buf.size())
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return;
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const unsigned char c = buf.pop_front();
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switch (c)
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{
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case NO_COMPRESS_SWAP:
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do_unswap(buf);
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break;
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case LZ4_COMPRESS:
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do_unswap(buf);
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do_decompress(buf);
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break;
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default:
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error(buf); // unknown op
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}
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}
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private:
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const bool asym;
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};
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class CompressLZ4v2 : public CompressLZ4Base
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{
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public:
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CompressLZ4v2(const Frame::Ptr& frame, const SessionStats::Ptr& stats, const bool asym_arg)
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: CompressLZ4Base(frame, stats),
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asym(asym_arg)
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{
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OPENVPN_LOG_COMPRESS("LZ4v2 init asym=" << asym_arg);
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}
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virtual const char *name() const { return "lz4v2"; }
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virtual void compress(BufferAllocated& buf, const bool hint)
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{
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// skip null packets
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if (!buf.size())
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return;
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if (hint && !asym)
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{
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if (do_compress(buf))
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{
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v2_push(buf, OVPN_COMPv2_LZ4);
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return;
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}
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}
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// indicate that we didn't compress
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v2_push(buf, OVPN_COMPv2_NONE);
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}
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virtual void decompress(BufferAllocated& buf)
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{
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// skip null packets
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if (!buf.size())
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return;
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const int c = v2_pull(buf);
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switch (c)
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{
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case OVPN_COMPv2_NONE:
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break;
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case OVPN_COMPv2_LZ4:
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do_decompress(buf);
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break;
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default:
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error(buf); // unknown op
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}
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}
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private:
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const bool asym;
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};
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}
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#endif
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