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author | Daniel Wilhelm <daniel@wili.li> | 2014-04-18 17:12:17 +0200 |
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committer | Daniel Wilhelm <daniel@wili.li> | 2014-04-18 17:12:17 +0200 |
commit | b654dbfa5f3e4a4d02f72023f7c5895635aa6396 (patch) | |
tree | 8c1dfe7f638c0fc7afc1d08bc2fc0fd0f8646e5e /shared/base64.h | |
parent | 3.17 (diff) | |
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3.18
Diffstat (limited to 'shared/base64.h')
-rw-r--r-- | shared/base64.h | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/shared/base64.h b/shared/base64.h new file mode 100644 index 00000000..4a81787c --- /dev/null +++ b/shared/base64.h @@ -0,0 +1,159 @@ +// ************************************************************************** +// * This file is part of the zenXML project. It is distributed under the * +// * Boost Software License, Version 1.0. See accompanying file * +// * LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt. * +// * Copyright (C) 2011 ZenJu (zhnmju123 AT gmx.de) * +// ************************************************************************** +#ifndef BASE64_HEADER_08473021856321840873021487213453214 +#define BASE64_HEADER_08473021856321840873021487213453214 + +#include <iterator> +#include <cassert> +#include "assert_static.h" + +namespace zen +{ +//http://en.wikipedia.org/wiki/Base64 +/* +Usage: + const std::string input = "Sample text"; + std::string output; + zen::encodeBase64(input.begin(), input.end(), std::back_inserter(output)); + //output contains "U2FtcGxlIHRleHQ=" +*/ +template <class InputIterator, class OutputIterator> +OutputIterator encodeBase64(InputIterator first, InputIterator last, OutputIterator result); //throw () + +template <class InputIterator, class OutputIterator> +OutputIterator decodeBase64(InputIterator first, InputIterator last, OutputIterator result); //throw () + + + + + + + + + + + + + + + + +//---------------------------------------- implementation ---------------------------------------- +namespace implementation +{ +const char ENCODING_MIME[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="; //64 chars for base64 encoding + padding char +const signed char DECODING_MIME[] = +{ + -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, 64, -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 +}; +const size_t INDEX_PAD = 64; +} + + +//http://en.wikipedia.org/wiki/Base64 +template <class InputIterator, class OutputIterator> inline +OutputIterator encodeBase64(InputIterator first, InputIterator last, OutputIterator result) +{ + using namespace implementation; + assert_static(sizeof(std::iterator_traits<InputIterator>::value_type) == 1); + assert_static(sizeof(ENCODING_MIME) == 65 + 1); + + while (first != last) + { + const unsigned char a = *first++; + *result++ = ENCODING_MIME[a >> 2]; + + if (first == last) + { + *result++ = ENCODING_MIME[((a & 0x3) << 4)]; + *result++ = ENCODING_MIME[INDEX_PAD]; + *result++ = ENCODING_MIME[INDEX_PAD]; + break; + } + const unsigned char b = *first++; + *result++ = ENCODING_MIME[((a & 0x3) << 4) | (b >> 4)]; + + if (first == last) + { + *result++ = ENCODING_MIME[((b & 0xf) << 2)]; + *result++ = ENCODING_MIME[INDEX_PAD]; + break; + } + const unsigned char c = *first++; + *result++ = ENCODING_MIME[((b & 0xf) << 2) | (c >> 6)]; + *result++ = ENCODING_MIME[c & 0x3f]; + } + + return result; +} + + +template <class InputIterator, class OutputIterator> inline +OutputIterator decodeBase64(InputIterator first, InputIterator last, OutputIterator result) +{ + using namespace implementation; + assert_static(sizeof(std::iterator_traits<InputIterator>::value_type) == 1); + assert_static(sizeof(DECODING_MIME) == 128); + + const int INDEX_END = INDEX_PAD + 1; + + auto readIndex = [&]() -> unsigned char //return index within [0, 64] or INDEX_END if end of input + { + while (true) + { + if (first == last) + return INDEX_END; + + unsigned char ch = *first++; + if (ch < 128) //skip all unknown characters (including carriage return, line-break, tab) + { + const int index = implementation::DECODING_MIME[ch]; + if (0 <= index && index <= INDEX_PAD) //respect padding + return index; + } + } + }; + + while (true) + { + const unsigned char index1 = readIndex(); + const unsigned char index2 = readIndex(); + if (index1 >= INDEX_PAD || index2 >= INDEX_PAD) + { + assert(index1 == INDEX_END && index2 == INDEX_END); + break; + } + *result++ = (index1 << 2) | (index2 >> 4); + + const unsigned char index3 = readIndex(); + if (index3 >= INDEX_PAD) //padding + { + assert(index3 == INDEX_PAD); + break; + } + *result++ = ((index2 & 0xf) << 4) | (index3 >> 2); + + const unsigned char index4 = readIndex(); + if (index4 >= INDEX_PAD) //padding + { + assert(index4 == INDEX_PAD); + break; + } + *result++ = ((index3 & 0x3) << 6) | index4; + } + return result; +} +} + +#endif //BASE64_HEADER_08473021856321840873021487213453214 |