#include <stdio.h>
#include <string.h>
#include <malloc.h>
#define BASE64_PAD64 '='
char base64_alphabet[] = 
{'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I',
'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R',
'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a',
'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's',
't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1',
'2', '3', '4', '5', '6', '7', '8', '9', '+','/'};
char base64_suffix_map[256] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1,
-1, -1, -1, -1, -1, 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, -1, -1, -1, -1, -1, -1, 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, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1};
static char cmove_bits(unsigned char src, unsigned lnum, unsigned rnum)
{
src <<= lnum;
src >>= rnum;
return src;
}
char* base64_encode(const char *data)
{
char *ret, *retpos;
int n, m, padnum = 0, retsize, dlen = strlen(data);
if (dlen == 0)
return NULL;
/**//* Account the result buffer size and alloc the memory for it. */
if ((dlen % 3) != 0)
padnum = 3 - dlen % 3;
retsize = (dlen + padnum) + ((dlen + padnum) * 1/3) + 1;
if((ret = (char*)malloc(retsize)) == NULL)
return NULL;
retpos = ret;
for (m=0; m<(dlen + padnum); m+=3)
{
*(retpos) = base64_alphabet[cmove_bits(*data, 0, 2)];
if (m == dlen + padnum - 3 && padnum != 0 && padnum != 2)
{ /**//* Whether the last bits-group suffice 24 bits. */
if (padnum == 1)
{ /**//* 16bit need pad one '='. */
*(retpos + 1) = base64_alphabet[cmove_bits(*data, 6, 2) + cmove_bits(*(data + 1), 0, 4)];
*(retpos + 2) = base64_alphabet[cmove_bits(*(data + 1), 4, 2)];
*(retpos + 3) = BASE64_PAD64;
}
}
else if (padnum == 2 &&((dlen == 1) || (m+3 == (dlen + padnum))))
{ /**//* 8bit need pad two'='. */
*(retpos + 1) = base64_alphabet[cmove_bits(*data, 6, 2)];
*(retpos + 2) = BASE64_PAD64;
*(retpos + 3) = BASE64_PAD64;
}
else
{ /**//* 24bit normal. */
*(retpos + 1) = base64_alphabet[cmove_bits(*data, 6, 2) + cmove_bits(*(data + 1), 0, 4)];
*(retpos + 2) = base64_alphabet[cmove_bits(*(data + 1), 4, 2) + cmove_bits(*(data + 2), 0, 6)];
*(retpos + 3) = base64_alphabet[*(data + 2) & 0x3f];
}
retpos += 4;
data += 3;
}
ret[retsize - 1] =0;
return ret;
}
char* base64_decode(const char *bdata)
{
char *ret = NULL, *retpos;
int n, m, padnum = 0, retsize, bdlen = strlen(bdata);
if(bdlen == 0)
return NULL;
if(bdlen % 4 != 0)
return NULL;
/**//* Whether the data have invalid base-64 characters? */
for(m = 0; m < bdlen; ++m)
{
if((bdata[m] != BASE64_PAD64) && (base64_suffix_map[bdata[m]] == 255))
goto LEND;
}
/**//* Account the output size. */
if(bdata[bdlen - 1] == '=')
padnum = 1;
if(bdata[bdlen - 1] == '=' && bdata[bdlen - 2] == '=')
padnum = 2;
retsize = (bdlen - 4) - (bdlen - 4) / 4 + (3 - padnum) + 1;
ret = (char*)malloc(retsize);
if(ret == NULL)
return NULL;
retpos = ret;
/**//* Begging to decode. */
for(m = 0; m < bdlen; m += 4)
{
*retpos = cmove_bits(base64_suffix_map[*bdata], 2, 0) + cmove_bits(base64_suffix_map[*(bdata + 1)], 0, 4);
if(m == bdlen - 4 && padnum != 0)
{ /**//* Only deal with last four bits. */
if(padnum == 1) /**//* Have one pad characters, only two availability characters. */
*(retpos + 1) = cmove_bits(base64_suffix_map[*(bdata + 1)], 4, 0) + cmove_bits(base64_suffix_map[*(bdata + 2)], 0, 2);
retpos += 3 - padnum;
}
else
{
*(retpos + 1) = cmove_bits(base64_suffix_map[*(bdata + 1)], 4, 0) + cmove_bits(base64_suffix_map[*(bdata + 2)], 0, 2);
*(retpos + 2) = cmove_bits(base64_suffix_map[*(bdata + 2)], 6, 0) + base64_suffix_map[*(bdata + 3)];
retpos += 3;
}
bdata += 4;
}
ret[retsize - 1] = 0;
LEND: return ret;
}
int main()
{
char str[] = "/*************************************************************************** \
* ebBase64Encode - encoding src with base64 and store into dst \
* \
* this routine encoding src with base64 and store into dst. Paramter slen \
* is to limit the max length of src to encoding. This routine will add \
* automatically for dst, but it won't check the buffer size of dst. So you \
* should keep the dst buffer size great than or equal (slen*4/3 + 4) bytes. \
* \
* RETURNS: the length of dst string (excludes the tailed '\0').";
printf("%s \n", base64_encode(str));
printf("%s \n", base64_decode(base64_encode(str)));
return 0;
}