nghttp2/src/base64.h

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/*
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* nghttp2 - HTTP/2 C Library
*
* Copyright (c) 2013 Tatsuhiro Tsujikawa
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef BASE64_H
#define BASE64_H
#include "nghttp2_config.h"
#include <string>
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namespace nghttp2 {
namespace base64 {
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template <typename InputIt> std::string encode(InputIt first, InputIt last) {
static constexpr char CHAR_TABLE[] = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/',
};
std::string res;
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size_t len = last - first;
if (len == 0) {
return res;
}
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size_t r = len % 3;
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res.resize((len + 2) / 3 * 4);
auto j = last - r;
auto p = std::begin(res);
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while (first != j) {
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uint32_t n = static_cast<uint8_t>(*first++) << 16;
n += static_cast<uint8_t>(*first++) << 8;
n += static_cast<uint8_t>(*first++);
*p++ = CHAR_TABLE[n >> 18];
*p++ = CHAR_TABLE[(n >> 12) & 0x3fu];
*p++ = CHAR_TABLE[(n >> 6) & 0x3fu];
*p++ = CHAR_TABLE[n & 0x3fu];
}
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if (r == 2) {
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uint32_t n = static_cast<uint8_t>(*first++) << 16;
n += static_cast<uint8_t>(*first++) << 8;
*p++ = CHAR_TABLE[n >> 18];
*p++ = CHAR_TABLE[(n >> 12) & 0x3fu];
*p++ = CHAR_TABLE[(n >> 6) & 0x3fu];
*p++ = '=';
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} else if (r == 1) {
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uint32_t n = static_cast<uint8_t>(*first++) << 16;
*p++ = CHAR_TABLE[n >> 18];
*p++ = CHAR_TABLE[(n >> 12) & 0x3fu];
*p++ = '=';
*p++ = '=';
}
return res;
}
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template <typename InputIt>
InputIt next_decode_input(InputIt first, InputIt last, const int *tbl) {
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for (; first != last; ++first) {
if (tbl[static_cast<size_t>(*first)] != -1 || *first == '=') {
break;
}
}
return first;
}
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template <typename InputIt> std::string decode(InputIt first, InputIt last) {
static constexpr int INDEX_TABLE[] = {
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57,
58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1};
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auto len = last - first;
if (len % 4 != 0) {
return "";
}
std::string res;
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res.resize(len / 4 * 3);
auto p = std::begin(res);
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for (; first != last;) {
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uint32_t n = 0;
for (int i = 1; i <= 4; ++i, ++first) {
auto idx = INDEX_TABLE[static_cast<size_t>(*first)];
if (idx == -1) {
if (i <= 2) {
return "";
}
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if (i == 3) {
if (*first == '=' && *(first + 1) == '=' && first + 2 == last) {
*p++ = n >> 16;
res.resize(p - std::begin(res));
return res;
}
return "";
}
if (*first == '=' && first + 1 == last) {
*p++ = n >> 16;
*p++ = n >> 8 & 0xffu;
res.resize(p - std::begin(res));
return res;
}
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return "";
}
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n += idx << (24 - i * 6);
}
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*p++ = n >> 16;
*p++ = n >> 8 & 0xffu;
*p++ = n & 0xffu;
}
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return res;
}
} // namespace base64
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} // namespace nghttp2
#endif // BASE64_H