git.sesse.net Git - casparcg/blob - common/base64.cpp

   1 /*
   2 * Copyright (c) 2011 Sveriges Television AB <info@casparcg.com>
   3 *
   4 * This file is part of CasparCG (www.casparcg.com).
   5 *
   6 * CasparCG is free software: you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation, either version 3 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * CasparCG is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with CasparCG. If not, see <http://www.gnu.org/licenses/>.
  18 *
  19 * Author: Helge Norberg, helge.norberg@svt.se
  20 */
  21
  22 #include "stdafx.h"
  23
  24 #include "base64.h"
  25
  26 #include <vector>
  27 #include <algorithm>
  28 #include <cstring>
  29
  30 #include <boost/archive/iterators/insert_linebreaks.hpp>
  31 #include <boost/archive/iterators/base64_from_binary.hpp>
  32 #include <boost/archive/iterators/binary_from_base64.hpp>
  33 #include <boost/archive/iterators/transform_width.hpp>
  34 #include <boost/archive/iterators/remove_whitespace.hpp>
  35 #include <boost/range/join.hpp>
  36 #include <boost/range/adaptor/sliced.hpp>
  37
  38 #include "except.h"
  39
  40 namespace caspar {
  41
  42 std::string to_base64(const char* data, size_t length)
  43 {
  44         using namespace boost::archive::iterators;
  45
  46         // From http://www.webbiscuit.co.uk/2012/04/02/base64-encoder-and-boost/
  47
  48         typedef
  49                 insert_linebreaks<         // insert line breaks every 76 characters
  50                         base64_from_binary<    // convert binary values to base64 characters
  51                                 transform_width<   // retrieve 6 bit integers from a sequence of 8 bit bytes
  52                                         const unsigned char *,
  53                                         6,
  54                                         8
  55                                 >
  56                         >,
  57                         76
  58                 >
  59                 base64_iterator; // compose all the above operations in to a new iterator
  60         std::vector<char> bytes;
  61         bytes.resize(length);
  62         std::memcpy(bytes.data(), data, length);
  63
  64         int padding = 0;
  65
  66         while (bytes.size() % 3 != 0)
  67         {
  68                 ++padding;
  69                 bytes.push_back(0x00);
  70         }
  71
  72         std::string result(base64_iterator(bytes.data()), base64_iterator(bytes.data() + length));
  73         result.insert(result.end(), padding, '=');
  74
  75         return std::move(result);
  76 }
  77
  78 std::vector<unsigned char> from_base64(const std::string& data)
  79 {
  80         // The boost base64 iterator will over-iterate the string if not a multiple
  81         // of 4, so we have to short circuit before.
  82         auto length = std::count_if(
  83                         data.begin(),
  84                         data.end(),
  85                         [] (char c) { return !std::isspace(static_cast<unsigned char>(c)); });
  86
  87         if (length % 4 != 0)
  88                 CASPAR_THROW_EXCEPTION(user_error() << msg_info(
  89                                 "The length of a base64 sequence must be a multiple of 4"));
  90
  91         int padding = 0;
  92         std::string zero_padding;
  93
  94         // binary_from_base64 does not support padding characters so we have to append base64 0 -> 'A' and then remove it after decoding
  95         if (data.length() >= 2)
  96         {
  97                 if (data[data.length() - 1] == '=')
  98                 {
  99                         ++padding;
 100                         zero_padding += 'A';
 101                 }
 102
 103                 if (data[data.length() - 2] == '=')
 104                 {
 105                         ++padding;
 106                         zero_padding += 'A';
 107                 }
 108         }
 109
 110         if (padding > 0)
 111         {
 112                 auto concatenated = boost::join(
 113                                 data | boost::adaptors::sliced(0, data.length() - padding),
 114                                 boost::make_iterator_range(zero_padding.cbegin(), zero_padding.cend()));
 115
 116                 // From https://svn.boost.org/trac/boost/ticket/5624
 117                 typedef boost::archive::iterators::transform_width<
 118                                 boost::archive::iterators::binary_from_base64<
 119                                         boost::archive::iterators::remove_whitespace<decltype(concatenated.begin())>
 120                                 >,
 121                                 8,
 122                                 6
 123                         > base64_iterator;
 124
 125                 std::vector<unsigned char> result(base64_iterator(concatenated.begin()), base64_iterator(concatenated.end()));
 126
 127                 result.resize(result.size() - padding);
 128
 129                 return std::move(result);
 130         }
 131         else
 132         {
 133                 // From https://svn.boost.org/trac/boost/ticket/5624
 134                 typedef boost::archive::iterators::transform_width<
 135                                 boost::archive::iterators::binary_from_base64<
 136                                         boost::archive::iterators::remove_whitespace<std::string::const_iterator>
 137                                 >,
 138                                 8,
 139                                 6
 140                         > base64_iterator;
 141                 std::vector<unsigned char> result(base64_iterator(data.begin()), base64_iterator(data.end()));
 142
 143                 return std::move(result);
 144         }
 145 }
 146
 147 }