base64.h

   1 /*
   2
   3     Slightly altered base64 part, derived from William Sherif, original notice
   4     below.
   5     Altered by: Thomas Lamprecht <t.lamprecht@proxmox.com>
   6
   7   Original Notice:
   8
   9   https://github.com/superwills/NibbleAndAHalf
  10   base64explained.h -- Fast base64 encoding and decoding.
  11   version 1.0.0, April 17, 2013 143a
  12
  13   EXPLAINS how the functions in base64.h work. You don't need this file,
  14   only base64.h is needed.
  15   Copyright (C) 2013 William Sherif
  16   This software is provided 'as-is', without any express or implied
  17   warranty.  In no event will the authors be held liable for any damages
  18   arising from the use of this software.
  19   Permission is granted to anyone to use this software for any purpose,
  20   including commercial applications, and to alter it and redistribute it
  21   freely, subject to the following restrictions:
  22   1. The origin of this software must not be misrepresented; you must not
  23      claim that you wrote the original software. If you use this software
  24      in a product, an acknowledgment in the product documentation would be
  25      appreciated but is not required.
  26   2. Altered source versions must be plainly marked as such, and must not be
  27      misrepresented as being the original software.
  28   3. This notice may not be removed or altered from any source distribution.
  29   William Sherif
  30   will.sherif@gmail.com
  31   YWxsIHlvdXIgYmFzZSBhcmUgYmVsb25nIHRvIHVz
  32 */
  33
  34 const static char* b64="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  35 // Converts binary data of length=len to base64 characters.
  36 char* base64( const void* binaryData, int len)
  37 {
  38     const unsigned char *bin = (const unsigned char*) binaryData;
  39
  40     int modulusLen = len % 3;
  41     // 2 gives 1 and 1 gives 2, but 0 gives 0, padding
  42     int pad = ((modulusLen & 1) << 1) + ((modulusLen & 2) >> 1);
  43
  44     int res_len = 4 * (len + pad) / 3;
  45     char *res = (char *) malloc(res_len + 1); // and one for the null
  46     if (!res) return 0; // really shouldn't happen on Linux
  47
  48     int byteNo; // needed for padding after the loop
  49     int rc = 0; // result counter
  50     for (byteNo = 0; byteNo <= len - 3; byteNo += 3) {
  51         unsigned char BYTE0 = bin[byteNo + 0];
  52         unsigned char BYTE1 = bin[byteNo + 1];
  53         unsigned char BYTE2 = bin[byteNo + 2];
  54         res[rc++] = b64[BYTE0 >> 2];
  55         res[rc++] = b64[((0x3 & BYTE0)<<4) + (BYTE1 >> 4)];
  56         res[rc++] = b64[((0x0f & BYTE1)<<2) + (BYTE2>>6)];
  57         res[rc++] = b64[0x3f & BYTE2];
  58     }
  59
  60     if (pad == 2) {
  61         res[rc++] = b64[bin[byteNo] >> 2];
  62         res[rc++] = b64[(0x3 & bin[byteNo]) << 4];
  63         res[rc++] = '=';
  64         res[rc++] = '=';
  65     } else if (pad == 1) {
  66         res[rc++] = b64[bin[byteNo] >> 2 ];
  67         res[rc++] = b64[((0x3 & bin[byteNo]) << 4) + (bin[byteNo + 1] >> 4)];
  68         res[rc++] = b64[(0x0f & bin[byteNo+1]) << 2];
  69         res[rc++] = '=';
  70     }
  71
  72     res[rc] = 0;
  73     return res;
  74 }