gclib2/modules/Crypt/base64.cxx

   1 /*
   2  * (c) Oleg Puchinin 2006
   3  * graycardinalster@gmail.com
   4  *
   5  */
   6
   7 #include "StdHeaders.h"
   8 #include "Macroses.h"
   9 #include <gclib2.h>
  10
  11
  12 /*! \file base64.c Кодирование/декодирование в/из Base64.
  13  */
  14
  15 const static char base64ABC[] =
  16 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  17 typedef unsigned char uchar_t;
  18
  19 #define S_(a) S[n * 3 + a]
  20 #define S__(a,b) (S[n * 3 + a] & b)
  21 #define S__l(a,b,c) ((S[n * 3 + a] & b) << c)
  22
  23 #define B1 buf[(n<<2)] = base64ABC[ (S_(0) >> 2) ];
  24 #define B2 buf[(n<<2) + 1] = base64ABC [ (S__l(0,0x3,4)) | S_(1) >> 4 ];
  25 #define B3 buf[(n<<2) + 2] = base64ABC [ S__l(1,0x0F,2) | S_(2) >> 6];
  26 #define B4 buf[(n<<2) + 3] = base64ABC [ S__(2,0x3F) ];
  27
  28 /*! \brief Закодировать в Base64.
  29  * \param S - исходный буфер.
  30  * \param SIZE - размер исходного буфера.
  31  */
  32 __export uchar_t * base64_code (unsigned char * S, int SIZE)
  33 {
  34     uchar_t c, *buf;
  35     int n;
  36
  37     c = (SIZE == 0) ? strlen ((const char *) S) % 3 : SIZE % 3;
  38     SIZE = (SIZE == 0) ? strlen ((const char *) S) / 3 : SIZE / 3;
  39
  40     buf = (uchar_t *) malloc (SIZE * 4 + 5);
  41
  42     for (n = 0; n < SIZE; ++n) {
  43             B1; B2; B3; B4;
  44     }
  45
  46     switch (c) {
  47     case 1:
  48         B1; B2;
  49         buf[(n<<2) + 2] = '=';
  50         buf[(n<<2) + 3] = '=';
  51         ++n;
  52         break;
  53     case 2:
  54         B1; B2; B3;
  55         buf[(n<<2) + 3] = '=';
  56         ++n;
  57         break;
  58     }
  59     buf[(n<<2)] = 0;
  60     return buf;
  61 }
  62
  63 #define BASE64(a) ((unsigned char) (strchr (base64ABC, S[(n<<2) + a]) - base64ABC))
  64
  65 /*! \brief Перекодировать из Base64.
  66  * \param S - исходный буфер.
  67  * \param SIZE - размер исходного буфера.
  68  */
  69 __export uchar_t * base64_decode (unsigned char * S, int SIZE)
  70 {
  71     unsigned char * ptr;
  72     int n;
  73
  74     if (SIZE % 4)
  75         return NULL;
  76
  77     SIZE = SIZE ? SIZE / 4 : strlen ((const char *) S) / 4;
  78     ptr = (uchar_t *) malloc (SIZE * 4 + 5);
  79
  80     for (n = 0; n < SIZE; n++) {
  81         ptr[n * 3] = (BASE64(0) << 2) | ( BASE64(1) >> 4);
  82         if (S[(n<<2) + 2] != '=') {
  83             ptr[n * 3 + 1] = ((BASE64(1) & 0x0F) << 4) | (BASE64(2) >> 2);
  84             if (S[(n<<2) + 3] != '=')
  85                 ptr[n * 3 + 2] = ((BASE64(2) & 0x03) << 6) | BASE64(3);
  86             else
  87                 ptr[n * 3 + 2] = 0;
  88         } else
  89             ptr[n * 3 +1] = 0;
  90     }
  91
  92     ++n;
  93     ptr [n * 3] = 0;
  94     return ptr;
  95 }
  96