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127 lines
4 KiB
C++
127 lines
4 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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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/ByteBuffer.h>
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#include <AK/StringView.h>
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#include <AK/Types.h>
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#include <AK/Vector.h>
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namespace AK {
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static constexpr u8 s_alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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static u8 s_table[256] = {};
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static bool s_initialized = false;
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static void build_lookup_table_if_needed()
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{
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if (s_initialized)
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return;
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for (size_t i = 0; i < sizeof(s_alphabet) - 1; ++i)
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s_table[s_alphabet[i]] = i;
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s_initialized = true;
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}
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ByteBuffer decode_base64(const StringView& input)
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{
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build_lookup_table_if_needed();
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auto get = [&](size_t offset, bool* is_padding = nullptr) -> u8 {
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if (offset >= input.length())
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return 0;
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if (input[offset] == '=') {
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if (is_padding)
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*is_padding = true;
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return 0;
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}
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return s_table[(u8)input[offset]];
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};
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Vector<u8> output;
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for (size_t i = 0; i < input.length(); i += 4) {
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bool in2_is_padding = false;
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bool in3_is_padding = false;
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u8 in0 = get(i);
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u8 in1 = get(i + 1);
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u8 in2 = get(i + 2, &in2_is_padding);
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u8 in3 = get(i + 3, &in3_is_padding);
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u8 out0 = (in0 << 2) | ((in1 >> 4) & 3);
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u8 out1 = ((in1 & 0xf) << 4) | ((in2 >> 2) & 0xf);
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u8 out2 = ((in2 & 0x3) << 6) | in3;
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output.append(out0);
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if (!in2_is_padding)
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output.append(out1);
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if (!in3_is_padding)
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output.append(out2);
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}
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return ByteBuffer::copy(output.data(), output.size());
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}
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ByteBuffer encode_base64(const StringView& input)
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{
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Vector<u8> output;
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auto get = [&](size_t offset, bool* need_padding = nullptr) -> u8 {
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if (offset >= input.length()) {
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if (need_padding)
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*need_padding = true;
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return 0;
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}
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return (u8)input[offset];
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};
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for (size_t i = 0; i < input.length(); i += 3) {
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bool is_8bit = false;
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bool is_16bit = false;
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u8 in0 = get(i);
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u8 in1 = get(i + 1, &is_16bit);
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u8 in2 = get(i + 2, &is_8bit);
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u8 index0 = (in0 >> 2) & 0x3f;
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u8 index1 = ((in0 << 4) | (in1 >> 4)) & 0x3f;
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u8 index2 = ((in1 << 2) | (in2 >> 6)) & 0x3f;
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u8 index3 = in2 & 0x3f;
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u8 out0 = s_alphabet[index0];
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u8 out1 = s_alphabet[index1];
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u8 out2 = is_16bit ? '=' : s_alphabet[index2];
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u8 out3 = is_8bit ? '=' : s_alphabet[index3];
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output.append(out0);
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output.append(out1);
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output.append(out2);
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output.append(out3);
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}
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return ByteBuffer::copy(output.data(), output.size());
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}
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}
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