mirror of
https://github.com/OpenVPN/openvpn3.git
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122 lines
2.7 KiB
C++
122 lines
2.7 KiB
C++
//
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// snappy.hpp
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// OpenVPN
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//
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// Copyright (c) 2012 OpenVPN Technologies, Inc. All rights reserved.
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//
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#ifndef OPENVPN_COMPRESS_SNAPPY_H
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#define OPENVPN_COMPRESS_SNAPPY_H
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// Implement Snappy compression.
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// Should only be included by compress.hpp
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#include <snappy.h>
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namespace openvpn {
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class CompressSnappy : public Compress
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{
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// magic number for Snappy compression
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enum {
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SNAPPY_COMPRESS = 0x68,
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};
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public:
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CompressSnappy(const Frame::Ptr& frame, const SessionStats::Ptr& stats, const bool asym_arg)
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: Compress(frame, stats),
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asym(asym_arg)
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{
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OPENVPN_LOG_COMPRESS("SNAPPY init asym=" << asym_arg);
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}
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virtual const char *name() const { return "snappy"; }
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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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// 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 (snappy::MaxCompressedLength(buf.size()) > work.max_size())
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{
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error(buf);
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return;
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}
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// do compress
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size_t comp_size;
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snappy::RawCompress((const char *)buf.c_data(), buf.size(), (char *)work.data(), &comp_size);
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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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OPENVPN_LOG_COMPRESS_VERBOSE("SNAPPY compress " << buf.size() << " -> " << comp_size);
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work.set_size(comp_size);
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do_swap(work, SNAPPY_COMPRESS);
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buf.swap(work);
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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 SNAPPY_COMPRESS:
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{
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do_unswap(buf);
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// initialize work buffer
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const size_t payload_size = frame->prepare(Frame::DECOMPRESS_WORK, work);
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// do uncompress
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size_t decomp_size;
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if (!snappy::GetUncompressedLength((const char *)buf.c_data(), buf.size(), &decomp_size)
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|| decomp_size > payload_size)
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{
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error(buf);
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break;
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}
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if (!snappy::RawUncompress((const char *)buf.c_data(), buf.size(), (char *)work.data()))
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{
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error(buf);
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break;
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}
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OPENVPN_LOG_COMPRESS_VERBOSE("SNAPPY 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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}
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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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BufferAllocated work;
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};
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} // namespace openvpn
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#endif // OPENVPN_COMPRESS_SNAPPY_H
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