| 217295cc |
** Copyright (C) 1998-2013 Sourcefire, Inc.
**
** Written by Patrick Mullen <pmullen@sourcefire.com>
** 9/11/2013 - Changed uint32_t to size_t
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License Version 2 as
** published by the Free Software Foundation. You may not use, modify or
** distribute this program under any other version of the GNU General
** Public License.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifdef HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include "sf_base64decode.h"
uint8_t sf_decode64tab[256] = {
100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
100,100,100,100,100,100,100,100,100,100,100,62 ,100,100,100, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61,100,100,100, 99,100,100,
100, 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, 25,100,100,100,100,100,
100, 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, 51,100,100,100,100,100,
100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100};
/* base64decode assumes the input data terminates with '=' and/or at the end of the input buffer
* at inbuf_size. If extra characters exist within inbuf before inbuf_size is reached, it will
* happily decode what it can and skip over what it can't. This is consistent with other decoders
* out there. So, either terminate the string, set inbuf_size correctly, or at least be sure the
* data is valid up until the point you care about. Note base64 data does NOT have to end with
* '=' and won't if the number of bytes of input data is evenly divisible by 3.
*/
int sf_base64decode(uint8_t *inbuf, size_t inbuf_size, uint8_t *outbuf, size_t outbuf_size, size_t *bytes_written)
{
uint8_t *cursor, *endofinbuf;
uint8_t *outbuf_ptr;
uint8_t base64data[4], *base64data_ptr; /* temporary holder for current base64 chunk */
uint8_t tableval_a, tableval_b, tableval_c, tableval_d;
size_t n;
size_t max_base64_chars; /* The max number of decoded base64 chars that fit into outbuf */
int error = 0;
/* This algorithm will waste up to 4 bytes but we really don't care.
At the end we're going to copy the exact number of bytes requested. */
max_base64_chars = (outbuf_size / 3) * 4 + 4; /* 4 base64 bytes gives 3 data bytes, plus
an extra 4 to take care of any rounding */
base64data_ptr = base64data;
endofinbuf = inbuf + inbuf_size;
/* Strip non-base64 chars from inbuf and decode */
n = 0;
*bytes_written = 0;
cursor = inbuf;
outbuf_ptr = outbuf;
while((cursor < endofinbuf) && (n < max_base64_chars)) {
if(sf_decode64tab[*cursor] != 100) {
*base64data_ptr++ = *cursor;
n++; /* Number of base64 bytes we've stored */
if(!(n % 4)) {
/* We have four databytes upon which to operate */
if((base64data[0] == '=') || (base64data[1] == '=')) {
/* Error in input data */
error = 1;
break;
}
/* retrieve values from lookup table */
tableval_a = sf_decode64tab[base64data[0]];
tableval_b = sf_decode64tab[base64data[1]];
tableval_c = sf_decode64tab[base64data[2]];
tableval_d = sf_decode64tab[base64data[3]];
if(*bytes_written < outbuf_size) {
*outbuf_ptr++ = (tableval_a << 2) | (tableval_b >> 4);
(*bytes_written)++;
}
if((base64data[2] != '=') && (*bytes_written < outbuf_size)) {
*outbuf_ptr++ = (tableval_b << 4) | (tableval_c >> 2);
(*bytes_written)++;
} else {
break;
}
if((base64data[3] != '=') && (*bytes_written < outbuf_size)) {
*outbuf_ptr++ = (tableval_c << 6) | tableval_d;
(*bytes_written)++;
} else {
break;
}
/* Reset our decode pointer for the next group of four */
base64data_ptr = base64data;
}
}
cursor++;
}
if(error)
return(-1);
else
return(0);
} |