src/lib/base64.c

/*
 * This code implements the BASE64 algorithm.
 * This code is in the public domain; do with it what you wish.
 *
 * @file base64.c
 * @brief This code implements the BASE64 algorithm
 * @author Matthieu Speder
 */
#include "base64.h"

static const char base64_digits[] =
{ 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, 0, 0, 0, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
  0, 0, 0, -1, 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, 0, 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, 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, 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,
  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, 0, 0, 0 };


char *
BASE64Decode (const char *src)
{
  size_t in_len = strlen (src);
  char *dest;
  char *result;

  if (in_len % 4)
  {
    /* Wrong base64 string length */
    return NULL;
  }
  result = dest = malloc (in_len / 4 * 3 + 1);
  if (NULL == result)
    return NULL; /* out of memory */
  while (*src)
  {
    char a = base64_digits[(unsigned char) *(src++)];
    char b = base64_digits[(unsigned char) *(src++)];
    char c = base64_digits[(unsigned char) *(src++)];
    char d = base64_digits[(unsigned char) *(src++)];
    *(dest++) = (a << 2) | ((b & 0x30) >> 4);
    if (c == (char) -1)
      break;
    *(dest++) = ((b & 0x0f) << 4) | ((c & 0x3c) >> 2);
    if (d == (char) -1)
      break;
    *(dest++) = ((c & 0x03) << 6) | d;
  }
  *dest = 0;
  return result;
}


/* end of base64.c */