base64.hpp

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#ifndef _PAINLESS_MESH_BASE64_HPP_
#define _PAINLESS_MESH_BASE64_HPP_
 
#include <string>
 
#include "painlessmesh/configuration.hpp"
 
namespace painlessmesh {
namespace base64 {
 
static inline bool is_base64(unsigned char c) {
  return (isalnum(c) || (c == '+') || (c == '/'));
}
 
static const TSTRING chars =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789+/";
 
inline TSTRING encode(unsigned char const* bytes_to_encode,
                      unsigned int in_len) {
  TSTRING ret;
  int i = 0;
  int j = 0;
  unsigned char char_array_3[3];
  unsigned char char_array_4[4];
 
  while (in_len--) {
    char_array_3[i++] = *(bytes_to_encode++);
    if (i == 3) {
      char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
      char_array_4[1] =
          ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
      char_array_4[2] =
          ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
      char_array_4[3] = char_array_3[2] & 0x3f;
 
      for (i = 0; (i < 4); i++) ret += chars[char_array_4[i]];
      i = 0;
    }
  }
 
  if (i) {
    for (j = i; j < 3; j++) char_array_3[j] = '\0';
 
    char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
    char_array_4[1] =
        ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
    char_array_4[2] =
        ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
    char_array_4[3] = char_array_3[2] & 0x3f;
    for (j = 0; (j < i + 1); j++) ret += chars[char_array_4[j]];
    while ((i++ < 3)) ret += '=';
  }
 
  return ret;
}
 
inline TSTRING encode(const TSTRING& str64) {
  return encode((unsigned char*)str64.c_str(), str64.length());
}
 
static const int B64index[256] = {
    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
    0,  0,  0,  0,  0,  0,  0,  62, 63, 62, 62, 63, 52, 53, 54, 55, 56, 57,
    58, 59, 60, 61, 0,  0,  0,  0,  0,  0,  0,  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, 0,  0,  0,  0,  63, 0,  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};
 
inline const TSTRING decode(const void* data, const size_t& len) {
  if (len == 0) return "";
 
  unsigned char* p = (unsigned char*)data;
  size_t j = 0, pad1 = len % 4 || p[len - 1] == '=',
         pad2 = pad1 && (len % 4 > 2 || p[len - 2] != '=');
  const size_t last = (len - pad1) / 4 << 2;
#ifdef PAINLESSMESH_ENABLE_STD_STRING
  TSTRING result(last / 4 * 3 + pad1 + pad2, '\0');
#else
  TSTRING result;
  result.reserve(last / 4 * 3 + pad1 + pad2);
  for (size_t i = 0; i < last / 4 * 3 + pad1 + pad2; ++i) result.concat('\0');
#endif
  unsigned char* str = (unsigned char*)&result[0];
 
  for (size_t i = 0; i < last; i += 4) {
    int n = B64index[p[i]] << 18 | B64index[p[i + 1]] << 12 |
            B64index[p[i + 2]] << 6 | B64index[p[i + 3]];
    str[j++] = n >> 16;
    str[j++] = n >> 8 & 0xFF;
    str[j++] = n & 0xFF;
  }
  if (pad1) {
    int n = B64index[p[last]] << 18 | B64index[p[last + 1]] << 12;
    str[j++] = n >> 16;
    if (pad2) {
      n |= B64index[p[last + 2]] << 6;
      str[j++] = n >> 8 & 0xFF;
    }
  }
  return result;
}
 
inline TSTRING decode(const TSTRING& str64) {
  return decode(str64.c_str(), str64.length());
}
}  // namespace base64
}  // namespace painlessmesh
#endif