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113 lines
3.4 KiB
C++
113 lines
3.4 KiB
C++
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/*
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base64.cpp and base64.h
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Copyright (C) 2004-2008 René Nyffenegger
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Modified by the Minetest Contributors.
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This source code is provided 'as-is', without any express or implied
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warranty. In no event will the author be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this source code must not be misrepresented; you must not
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claim that you wrote the original source code. If you use this source code
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original source code.
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3. This notice may not be removed or altered from any source distribution.
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René Nyffenegger rene.nyffenegger@adp-gmbh.ch
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*/
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#include "base64.h"
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#include <string>
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#include <string_view>
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static const std::string base64_chars =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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"abcdefghijklmnopqrstuvwxyz"
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"0123456789+/";
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static const std::string base64_chars_padding_1 = "AEIMQUYcgkosw048";
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static const std::string base64_chars_padding_2 = "AQgw";
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static inline bool is_base64(unsigned char c)
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{
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return (c >= '0' && c <= '9')
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|| (c >= 'A' && c <= 'Z')
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|| (c >= 'a' && c <= 'z')
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|| c == '+' || c == '/';
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}
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bool base64_is_valid(const std::string_view &s)
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{
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size_t i = 0;
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for (; i < s.size(); ++i)
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if (!is_base64(s[i]))
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break;
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unsigned char padding = 3 - ((i + 3) % 4);
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if ((padding == 1 && base64_chars_padding_1.find(s[i - 1]) == std::string::npos)
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|| (padding == 2 && base64_chars_padding_2.find(s[i - 1]) == std::string::npos)
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|| padding == 3)
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return false;
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int actual_padding = s.size() - i;
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// omission of padding characters is allowed
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if (actual_padding == 0)
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return true;
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// remaining characters (max. 2) may only be padding
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for (; i < s.size(); ++i)
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if (s[i] != '=')
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return false;
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// number of padding characters needs to match
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return padding == actual_padding;
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}
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std::vector<unsigned char> base64_decode(const std::string_view &encoded_string) {
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std::size_t in_len = encoded_string.size();
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std::size_t i = 0, j = 0, in_ = 0;
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unsigned char char_array_4[4], char_array_3[3];
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std::vector<unsigned char> ret;
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ret.reserve(3 * in_len / 4 + 1);
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while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
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char_array_4[i++] = encoded_string[in_]; in_++;
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if (i ==4) {
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for (i = 0; i <4; i++)
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char_array_4[i] = base64_chars.find(char_array_4[i]);
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char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
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char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
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char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
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for (i = 0; (i < 3); i++)
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ret.push_back(char_array_3[i]);
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i = 0;
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}
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}
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if (i) {
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for (j = i; j <4; j++)
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char_array_4[j] = 0;
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for (j = 0; j <4; j++)
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char_array_4[j] = base64_chars.find(char_array_4[j]);
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char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
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char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
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char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
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for (j = 0; (j < i - 1); j++)
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ret.push_back(char_array_3[j]);
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}
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return ret;
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}
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