f532421c9c
This commit adds a verify-less try_create method to the Zlib decompressor to allow for graceful failures of parsing the Zlib headers.
92 lines
2.9 KiB
C++
92 lines
2.9 KiB
C++
/*
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* Copyright (c) 2020, the SerenityOS developers
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <AK/Span.h>
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#include <AK/Types.h>
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#include <AK/Vector.h>
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#include <LibCompress/Deflate.h>
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#include <LibCompress/Zlib.h>
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namespace Compress {
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Optional<Zlib> Zlib::try_create(ReadonlyBytes data)
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{
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if (data.size() < 6)
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return {}; // header + footer size is 6
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Zlib zlib { data };
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u8 compression_info = data.at(0);
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u8 flags = data.at(1);
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zlib.m_compression_method = compression_info & 0xF;
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zlib.m_compression_info = (compression_info >> 4) & 0xF;
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zlib.m_check_bits = flags & 0xF;
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zlib.m_has_dictionary = (flags >> 5) & 0x1;
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zlib.m_compression_level = (flags >> 6) & 0x3;
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if (zlib.m_compression_method != 8 || zlib.m_compression_info > 7)
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return {}; // non-deflate compression
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if (zlib.m_has_dictionary)
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return {}; // we dont support pre-defined dictionaries
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if ((compression_info * 256 + flags) % 31 != 0)
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return {}; // error correction code doesnt match
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zlib.m_data_bytes = data.slice(2, data.size() - 2 - 4);
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return zlib;
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}
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Zlib::Zlib(const ReadonlyBytes& data)
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: m_input_data(data)
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{
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}
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Optional<ByteBuffer> Zlib::decompress()
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{
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return DeflateDecompressor::decompress_all(m_data_bytes);
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}
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Optional<ByteBuffer> Zlib::decompress_all(ReadonlyBytes bytes)
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{
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auto zlib = try_create(bytes);
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if (!zlib.has_value())
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return {};
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return zlib->decompress();
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}
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u32 Zlib::checksum()
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{
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if (!m_checksum) {
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auto bytes = m_input_data.slice(m_input_data.size() - 4, 4);
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m_checksum = bytes.at(0) << 24 | bytes.at(1) << 16 | bytes.at(2) << 8 || bytes.at(3);
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}
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return m_checksum;
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}
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}
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