#ifndef _MACARON_BASE64_H_ | |
#define _MACARON_BASE64_H_ | |
/** | |
* The MIT License (MIT) | |
* Copyright (c) 2016 tomykaira | |
* | |
* 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. | |
*/ | |
#include <string> | |
namespace macaron { | |
class Base64 { | |
public: | |
static std::string Encode(const std::string data) { | |
static constexpr char sEncodingTable[] = { | |
'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', '+', '/' | |
}; | |
size_t in_len = data.size(); | |
size_t out_len = 4 * ((in_len + 2) / 3); | |
std::string ret(out_len, '\0'); | |
size_t i; | |
char *p = const_cast<char*>(ret.c_str()); | |
for (i = 0; i < in_len - 2; i += 3) { | |
*p++ = sEncodingTable[(data[i] >> 2) & 0x3F]; | |
*p++ = sEncodingTable[((data[i] & 0x3) << 4) | ((int) (data[i + 1] & 0xF0) >> 4)]; | |
*p++ = sEncodingTable[((data[i + 1] & 0xF) << 2) | ((int) (data[i + 2] & 0xC0) >> 6)]; | |
*p++ = sEncodingTable[data[i + 2] & 0x3F]; | |
} | |
if (i < in_len) { | |
*p++ = sEncodingTable[(data[i] >> 2) & 0x3F]; | |
if (i == (in_len - 1)) { | |
*p++ = sEncodingTable[((data[i] & 0x3) << 4)]; | |
*p++ = '='; | |
} | |
else { | |
*p++ = sEncodingTable[((data[i] & 0x3) << 4) | ((int) (data[i + 1] & 0xF0) >> 4)]; | |
*p++ = sEncodingTable[((data[i + 1] & 0xF) << 2)]; | |
} | |
*p++ = '='; | |
} | |
return ret; | |
} | |
static std::string Decode(const std::string& input, std::string& out) { | |
static constexpr unsigned char kDecodingTable[] = { | |
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, | |
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, | |
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63, | |
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64, | |
64, 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, 64, 64, 64, 64, 64, | |
64, 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, 64, 64, 64, 64, 64, | |
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, | |
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, | |
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, | |
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, | |
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, | |
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, | |
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, | |
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64 | |
}; | |
size_t in_len = input.size(); | |
if (in_len % 4 != 0) return "Input data size is not a multiple of 4"; | |
size_t out_len = in_len / 4 * 3; | |
if (input[in_len - 1] == '=') out_len--; | |
if (input[in_len - 2] == '=') out_len--; | |
out.resize(out_len); | |
for (size_t i = 0, j = 0; i < in_len;) { | |
uint32_t a = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])]; | |
uint32_t b = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])]; | |
uint32_t c = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])]; | |
uint32_t d = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])]; | |
uint32_t triple = (a << 3 * 6) + (b << 2 * 6) + (c << 1 * 6) + (d << 0 * 6); | |
if (j < out_len) out[j++] = (triple >> 2 * 8) & 0xFF; | |
if (j < out_len) out[j++] = (triple >> 1 * 8) & 0xFF; | |
if (j < out_len) out[j++] = (triple >> 0 * 8) & 0xFF; | |
} | |
return ""; | |
} | |
}; | |
} | |
#endif /* _MACARON_BASE64_H_ */ |
Just a note to people who are thinking of copying and pasting this into their projects: don't! There are several issues with the example here, and I've unfortunately seen people copying this into their productions systems before.
If you are looking for a safer modern Cpp Base64 alternative, I've made a post on how to write a good C++ Base64 encoder. At the very least you will learn how base64 encoding works.
Thank you @tomykaira
C version: https://github.com/skullchap/b64/
static std::string Encode(const std::string data)
Did you forget a '&'?
+1 @ravstrix , otherwise this seems like a copy
when the input data length is 1, it will be crashed.
static std::string Encode(const std::string data) {
static constexpr char sEncodingTable[] = {
'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', '+', '/'
};
size_t in_len = data.size();
size_t out_len = 4 * ((in_len + 2) / 3);
std::string ret(out_len, '\0');
size_t i = 0;
char *p = const_cast<char*>(ret.c_str());
if (in_len >= 2) {
for (i = 0; i < in_len - 2; i += 3) {
*p++ = sEncodingTable[(data[i] >> 2) & 0x3F];
*p++ = sEncodingTable[((data[i] & 0x3) << 4) | ((int) (data[i + 1] & 0xF0) >> 4)];
*p++ = sEncodingTable[((data[i + 1] & 0xF) << 2) | ((int) (data[i + 2] & 0xC0) >> 6)];
*p++ = sEncodingTable[data[i + 2] & 0x3F];
}
}
if (i < in_len) {
*p++ = sEncodingTable[(data[i] >> 2) & 0x3F];
if (i == (in_len - 1)) {
*p++ = sEncodingTable[((data[i] & 0x3) << 4)];
*p++ = '=';
}
else {
*p++ = sEncodingTable[((data[i] & 0x3) << 4) | ((int) (data[i + 1] & 0xF0) >> 4)];
*p++ = sEncodingTable[((data[i + 1] & 0xF) << 2)];
}
*p++ = '=';
}
return ret;
}
I fixed this:
size_t i=0; // init i=0
char* p = const_cast<char*>(ret.c_str());
if (in_len >= 2) { // skip when in_len less than 2
for (i = 0; i < in_len - 2; i += 3) {
*p++ = sEncodingTable[(data[i] >> 2) & 0x3F];
*p++ = sEncodingTable[((data[i] & 0x3) << 4) | ((int)(data[i + 1] & 0xF0) >> 4)];
*p++ = sEncodingTable[((data[i + 1] & 0xF) << 2) | ((int)(data[i + 2] & 0xC0) >> 6)];
*p++ = sEncodingTable[data[i + 2] & 0x3F];
}
}
@Paril,
And from the document you just cited under 21.4.7.1 basic_string accessors for
data
andc_str
(p. 659):