132 lines
5.6 KiB
C
132 lines
5.6 KiB
C
/*
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** Copyright (C) 2013-2022 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
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** Copyright (C) 1998-2013 Sourcefire, Inc.
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**
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** Written by Patrick Mullen <pmullen@sourcefire.com>
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** 9/11/2013 - Changed uint32_t to size_t
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**
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** This program is free software; you can redistribute it and/or modify
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** it under the terms of the GNU General Public License Version 2 as
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** published by the Free Software Foundation. You may not use, modify or
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** distribute this program under any other version of the GNU General
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** Public License.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program; if not, write to the Free Software
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** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#ifdef HAVE_CONFIG_H
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#include "clamav-config.h"
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#endif
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#include "sf_base64decode.h"
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// clang-format off
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uint8_t sf_decode64tab[256] = {
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100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
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100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
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100,100,100,100,100,100,100,100,100,100,100,62 ,100,100,100, 63,
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52, 53, 54, 55, 56, 57, 58, 59, 60, 61,100,100,100, 99,100,100,
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100, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,100,100,100,100,100,
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100, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
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41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,100,100,100,100,100,
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100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
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100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
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100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
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100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
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100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
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100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
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100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,
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100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100};
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// clang-format on
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/* base64decode assumes the input data terminates with '=' and/or at the end of the input buffer
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* at inbuf_size. If extra characters exist within inbuf before inbuf_size is reached, it will
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* happily decode what it can and skip over what it can't. This is consistent with other decoders
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* out there. So, either terminate the string, set inbuf_size correctly, or at least be sure the
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* data is valid up until the point you care about. Note base64 data does NOT have to end with
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* '=' and won't if the number of bytes of input data is evenly divisible by 3.
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*/
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int sf_base64decode(uint8_t *inbuf, size_t inbuf_size, uint8_t *outbuf, size_t outbuf_size, size_t *bytes_written)
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{
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uint8_t *cursor, *endofinbuf;
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uint8_t *outbuf_ptr;
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uint8_t base64data[4], *base64data_ptr; /* temporary holder for current base64 chunk */
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uint8_t tableval_a, tableval_b, tableval_c, tableval_d;
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size_t n;
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size_t max_base64_chars; /* The max number of decoded base64 chars that fit into outbuf */
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int error = 0;
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/* This algorithm will waste up to 4 bytes but we really don't care.
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At the end we're going to copy the exact number of bytes requested. */
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max_base64_chars = (outbuf_size / 3) * 4 + 4; /* 4 base64 bytes gives 3 data bytes, plus
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an extra 4 to take care of any rounding */
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base64data_ptr = base64data;
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endofinbuf = inbuf + inbuf_size;
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/* Strip non-base64 chars from inbuf and decode */
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n = 0;
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*bytes_written = 0;
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cursor = inbuf;
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outbuf_ptr = outbuf;
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while ((cursor < endofinbuf) && (n < max_base64_chars)) {
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if (sf_decode64tab[*cursor] != 100) {
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*base64data_ptr++ = *cursor;
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n++; /* Number of base64 bytes we've stored */
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if (!(n % 4)) {
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/* We have four databytes upon which to operate */
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if ((base64data[0] == '=') || (base64data[1] == '=')) {
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/* Error in input data */
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error = 1;
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break;
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}
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/* retrieve values from lookup table */
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tableval_a = sf_decode64tab[base64data[0]];
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tableval_b = sf_decode64tab[base64data[1]];
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tableval_c = sf_decode64tab[base64data[2]];
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tableval_d = sf_decode64tab[base64data[3]];
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if (*bytes_written < outbuf_size) {
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*outbuf_ptr++ = (tableval_a << 2) | (tableval_b >> 4);
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(*bytes_written)++;
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}
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if ((base64data[2] != '=') && (*bytes_written < outbuf_size)) {
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*outbuf_ptr++ = (tableval_b << 4) | (tableval_c >> 2);
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(*bytes_written)++;
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} else {
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break;
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}
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if ((base64data[3] != '=') && (*bytes_written < outbuf_size)) {
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*outbuf_ptr++ = (tableval_c << 6) | tableval_d;
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(*bytes_written)++;
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} else {
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break;
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}
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/* Reset our decode pointer for the next group of four */
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base64data_ptr = base64data;
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}
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}
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cursor++;
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}
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if (error)
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return (-1);
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else
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return (0);
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}
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