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#include "base64.h"
#include <assert.h>
#include <stdint.h>
static const unsigned char base64_enc_map[64] =
{
'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', '+', '/'
};
static const unsigned char base64_dec_map[128] =
{
127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
127, 127, 127, 62, 127, 127, 127, 63, 52, 53,
54, 55, 56, 57, 58, 59, 60, 61, 127, 127,
127, 64, 127, 127, 127, 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, 127, 127, 127, 127, 127, 127, 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, 127, 127, 127, 127, 127
};
#define BASE64_SIZE_T_MAX ( (size_t) -1 ) /* SIZE_T_MAX is not standard */
size_t base64_size(size_t buffer_size) {
size_t olen;
int result = base64_encode(NULL, 0, &olen, NULL, buffer_size);
assert(result == ERR_BASE64_BUFFER_TOO_SMALL);
return olen;
}
/*
* Encode a buffer into base64 format
*/
int base64_encode( unsigned char *dst, size_t dlen, size_t *olen,
const unsigned char *src, size_t slen )
{
size_t i, n;
int C1, C2, C3;
unsigned char *p;
if( slen == 0 )
{
*olen = 0;
return( 0 );
}
n = slen / 3 + ( slen % 3 != 0 );
if( n > ( BASE64_SIZE_T_MAX - 1 ) / 4 )
{
*olen = BASE64_SIZE_T_MAX;
return( ERR_BASE64_BUFFER_TOO_SMALL );
}
n *= 4;
if( ( dlen < n + 1 ) || ( NULL == dst ) )
{
*olen = n + 1;
return( ERR_BASE64_BUFFER_TOO_SMALL );
}
n = ( slen / 3 ) * 3;
for( i = 0, p = dst; i < n; i += 3 )
{
C1 = *src++;
C2 = *src++;
C3 = *src++;
*p++ = base64_enc_map[(C1 >> 2) & 0x3F];
*p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F];
*p++ = base64_enc_map[(((C2 & 15) << 2) + (C3 >> 6)) & 0x3F];
*p++ = base64_enc_map[C3 & 0x3F];
}
if( i < slen )
{
C1 = *src++;
C2 = ( ( i + 1 ) < slen ) ? *src++ : 0;
*p++ = base64_enc_map[(C1 >> 2) & 0x3F];
*p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F];
if( ( i + 1 ) < slen )
*p++ = base64_enc_map[((C2 & 15) << 2) & 0x3F];
else *p++ = '=';
*p++ = '=';
}
*olen = p - dst;
*p = 0;
return( 0 );
}
/*
* Decode a base64-formatted buffer
*/
int base64_decode( unsigned char *dst, size_t dlen, size_t *olen,
const unsigned char *src, size_t slen )
{
size_t i, n;
uint32_t j, x;
unsigned char *p;
/* First pass: check for validity and get output length */
for( i = n = j = 0; i < slen; i++ )
{
/* Skip spaces before checking for EOL */
x = 0;
while( i < slen && src[i] == ' ' )
{
++i;
++x;
}
/* Spaces at end of buffer are OK */
if( i == slen )
break;
if( ( slen - i ) >= 2 &&
src[i] == '\r' && src[i + 1] == '\n' )
continue;
if( src[i] == '\n' )
continue;
/* Space inside a line is an error */
if( x != 0 )
return( ERR_BASE64_INVALID_CHARACTER );
if( src[i] == '=' && ++j > 2 )
return( ERR_BASE64_INVALID_CHARACTER );
if( src[i] > 127 || base64_dec_map[src[i]] == 127 )
return( ERR_BASE64_INVALID_CHARACTER );
if( base64_dec_map[src[i]] < 64 && j != 0 )
return( ERR_BASE64_INVALID_CHARACTER );
n++;
}
if( n == 0 )
{
*olen = 0;
return( 0 );
}
/* The following expression is to calculate the following formula without
* risk of integer overflow in n:
* n = ( ( n * 6 ) + 7 ) >> 3;
*/
n = ( 6 * ( n >> 3 ) ) + ( ( 6 * ( n & 0x7 ) + 7 ) >> 3 );
n -= j;
if( dst == NULL || dlen < n )
{
*olen = n;
return( ERR_BASE64_BUFFER_TOO_SMALL );
}
for( j = 3, n = x = 0, p = dst; i > 0; i--, src++ )
{
if( *src == '\r' || *src == '\n' || *src == ' ' )
continue;
j -= ( base64_dec_map[*src] == 64 );
x = ( x << 6 ) | ( base64_dec_map[*src] & 0x3F );
if( ++n == 4 )
{
n = 0;
if( j > 0 ) *p++ = (unsigned char)( x >> 16 );
if( j > 1 ) *p++ = (unsigned char)( x >> 8 );
if( j > 2 ) *p++ = (unsigned char)( x );
}
}
*olen = p - dst;
return( 0 );
}